Course Notes - 1B

International Diploma in Occupational Safety and Health Unit 1B

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International Diploma - Course Contents Unit 1 Principles of Health and Safety Management

Element 1A – Fundamentals of Health and Safety Management Preventing Accidents

1A1

International Occupational Health and Safety Framework

1A2

Health and Safety Management Systems

1A3

Risk Assessment

1A4

Safe Workplace

1A5

Control of Contractors

1A6

Safe Systems of Work

1A7

Personal Protective Equipment

1A8

Human Failure

1A9

Role of the Health and Safety Practitioner

1A10

Protecting the Environment

1A11

Engaging the Workforce

1A12

Element 1B – Applied Health and Safety Management Fire

1B1

Explosion

1B2

Major Accident Hazards

1B3

Emergency Control

1B4

Work Equipment

1B5

Occupational Transport and Driving

1B6

Mechanical Handling and Lifting Operations

1B7

Electrical Safety

1B8

Pressure Systems

1B9

Carriage of Dangerous Goods

1B10

Construction and Demolition

1B11

Working at Height

1B12

Working in Confines Spaces

1B13

Lone Working

1B14

Violence against Employees

1B15

Reporting and Investigating Incidents

1B16

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© British Safety Council

BSC International Diploma | Unit 1 Element 1B: Applied Health and Safety Management

C O N T E N T S Study Unit 1B1

Title

Page

Fire

FIRE PRINCIPLES ............................................................................................................................................... 3 PHYSICS OF FIRE – FIRE TRIANGLE ............................................................................................................................. 3 FIRE PROPAGATION (FIRE SPREAD) .............................................................................................................................. 4 IGNITION TEMPERATURES ......................................................................................................................................... 5 FIRE CLASSIFICATIONS ............................................................................................................................................ 7 FIRE RISK ASSESSMENT ..................................................................................................................................... 8 FIRE HAZARDS AND ASSESSMENT OF RISK ..................................................................................................................... 8 SYSTEMS FOR THE PREVENTION, DETECTION AND CONTROL OF FIRE ........................................................... 11 MEANS OF DETECTION AND RAISING THE ALARM ........................................................................................................... 11 DESIGN AND APPLICATION OF FIRE DETECTION AND ALARM SYSTEMS .................................................................................. 11 PRINCIPAL COMPONENTS OF SYSTEMS – DETECTION AND SIGNALLING ................................................................................. 11 MANUAL AND AUTOMATIC ALARM SYSTEMS .................................................................................................................. 14 WHEN AND HOW TO FIGHT A FIRE ............................................................................................................................ 15 HOW TO ESTABLISH MEANS OF ESCAPE FROM FIRE ........................................................................................ 19 GENERAL PRINCIPLES ............................................................................................................................................ 19 PROTECTION OF ESCAPE ROUTES .............................................................................................................................. 19 EMERGENCY LIGHTING........................................................................................................................................... 20 SIGNS/ NOTICES.................................................................................................................................................. 20 DISABLED PERSONS .............................................................................................................................................. 20 FIRE EMERGENCY ARRANGEMENTS ................................................................................................................. 22 GENERAL EVACUATION PROCEDURES .......................................................................................................................... 22 FUNCTIONS OF FIRE WARDENS AND FIRE MARSHALS ...................................................................................................... 22 POST-EVACUATION DEBRIEF .................................................................................................................................... 23 PRINCIPLES OF FIRE SAFETY TRAINING ......................................................................................................... 24 EXTINGUISHER TRAINING ....................................................................................................................................... 24 EVACUATION PROCEDURE ....................................................................................................................................... 24

BSC International Diploma – Element 1B | Applied Health and Safety Management

BSC International Diploma | Unit 1 Element 1B: Applied Health and Safety Management Study Unit 1B1 | Fire Learning Outcomes When you have worked through this Study Unit, you will be able to:

1.B.1.1 Explain the principles of fire 1.B.1.2 Describe the process and main stages of a fire risk assessment 1.B.1.3 Advise employers on systems for the prevention, detection and control of fire 1.B.1.4 Advise employers on how to establish means of escape from fire 1.B.1.5 Explain the principles of fire emergency procedures 1.B.1.6 Outline the principles of fire safety training

Unit 1:

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©British Safety Council


Fire Principles Physics of Fire – Fire Triangle What do we need to start a fire? 

First, we need a combustible substance or fuel (wood, paper, plastics, etc.).



Secondly, we require oxygen (usually from air).



Then we have to apply an ignition source.



After which, if the conditions are right, the substance will catch fire, i.e. heat and light will be evolved, accompanied by volumes of smoke and gases which will rise away from the fire.

The first three factors above form the basis of the Fire Triangle, and all must be present to produce and sustain a fire.

The Triangle of

Combustion

Fuel Fuel takes the form of vapours and/or gases emitted by liquids and solids which themselves do not burn. The vapours and gases mix with air, oxygen or other oxidising agents, e.g. chlorine. If they come within the flammable range they may be ignited. Dusts of combustible solids will also ignite under certain conditions.

Air/Oxygen Although under certain unusual circumstances it is possible to produce combustion-like chemical reactions with materials such as chlorine or sulphur, it is safe to say that nearly all combustion requires the presence of oxygen. The higher the concentration of oxygen in an atmosphere, the more rapidly will burning proceed.

Ignition It is often easily overlooked that to start a fire it may be necessary to heat to a sufficient degree only a very small quantity of fuel and oxygen mixture. Then, since fires are by definition exothermic, the very small fire started by a tiny heat source supplies to its surroundings more heat than it absorbs, thus enabling it to ignite more fuel and oxygen mixture, and so on, until very quickly there is more heat available than is needed to propagate a large fire. The heat may be provided by various sources of ignition, for example: 

Open flames - matches, welding torches.



Electrical sparking sources.

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Overheating of surfaces due to excessive temperatures. 

Hot surfaces – dryers.



Spontaneous ignition.



Sparks from grinding or tools.



Static electricity.



Friction.

Fire Propagation (fire spread) Once a fire has started, there are four methods by which it can spread – convection, conduction, radiation and direct burning.

Radiation Radiation is the general term for the process by which energy is lost from a source without direct contact. Heat radiation, therefore, refers to the process whereby the heat given off by hot objects passes through air and through certain types of transparent material (such as glass). This radiant heat can, in itself, be sufficient to act as a source of ignition. For example, radiators are an obvious source of heat, and clothes that are left to dry too close to them may catch fire. Similarly, light bulbs give out heat (and in the case of certain types of spot lights, a large amount of heat) and any fabrics or flammable materials that are too close may start to burn. The intensity of radiant heat diminishes with the distance from its source. However, depending on the temperature of the source, heat transference may take place over quite large distances. For example, a fire burning on one side of a street may be sufficient to cause materials on the other side of the street to combust.

Convection Convection is the process whereby heat moves through a gas or liquid. When a gas or liquid – for example, air or water – is heated, it expands and becomes less dense. As a result, it rises and cooler air or water is drawn in to replace it, creating a current. Convection currents created in the air by fire are a major means of fire spread. They may carry burning materials through the air and into contact with other combustible materials, and also, depending upon the intensity of the fire and the heat generated, create strong, localised winds which may fan the flames and cause flare ups.

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Convection Currents

Conduction Heat may be transmitted along certain materials, known as conductors, without those materials themselves actually burning. This is particularly the case with metals. Thus, the heat generated by a fire (or any other process producing heat) may be transferred to a separate location where it can act as a source of ignition. This has considerable implications for many buildings, where there is widespread use of metal within both the structure of the building (for example, steel girders) and the services that run through it, such as pipes and various types of ducting.

Conduction

Ignition Temperatures Flash Point Flash point is the lowest temperature at which sufficient vapour is given off to flash, i.e. ignite momentarily, when a source of ignition is applied. Substances which have a flash point below ambient temperature will pose a hazard as they will be producing a flammable vapour. Liquids which produce flammable atmospheres have their flash point measured in a standard test. The usual test utilises a small container about half full of liquid which is slowly warmed up, the atmosphere above the liquid level being tested at regular intervals with an igniter. When the flash occurs the temperature is noted. The test is carried out in an Abel apparatus. In the UK Liquids with a flash point lower than 0ºC and a boiling point lower than or equal to 35ºC are classified as extremely flammable. Those with a flash point below 21ºC but which

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are not extremely flammable are classified as highly flammable. Those with a flash point between 21ºC and 55ºC are classified flammable. Some common flash points are given in the following table. Some Common Solvents and their Flash Points FLASH POINT (ABEL CLOSED CUP) (°°C)

SOLVENT Butanone (methyl ethyl ketone, MEK) Carbon disulphide (CS2) Diesel oil Ethyl ethanoate (ethyl acetate) Ethoxyethane (diethyl ether) Methylated spirit Methylbenzene (toluene) Petrol Phenylethene (styrene) Propanone (acetone)

−7 −30 (Auto ign temp 102°C) +40 (approx.) −4 −40 10 4 −40 (approx.) 32 −17

Note that: 

Petrol is far more dangerous than diesel oil if it is spilled because the vapours from petrol will ignite from any fortuitous ignition source, whereas those from diesel will not. Contemplate such a spillage into the bilges of a boat and you can see why the insurance premiums are higher if the boat has a petrol engine.



Substances with very low flash points are very volatile. Ether, acetone and carbon disulphide are all notoriously dangerous.

Flash point tests may be applied to any liquid and not just hydrocarbons.

Fire Point Fire point is defined as the lowest temperature at which the application of an ignition source will lead to continuing burning. The temperature is usually just above the flash point and, when the vapours are ignited, the heat of the flash raises the temperature of the liquid surface to a point where sufficient vapour is given off to sustain combustion.

Auto Ignition Temperature (AIT) This is the lowest temperature at which the substance will ignite without the application of an ignition source. Different substances have different AITs. The material can be a solid, liquid or gas, and once ignition has taken place, the material will sustain the self-ignition in the absence of spark or flame. The value is influenced by the material's size, the shape of the heated surface and, in the case of a solid, the rate of heating and other factors. A chemical reaction can supply the heat to raise a substance above its auto ignition temperature. Haystacks have been known to ignite due to bacteriological action causing internal heat rises. This phenomenon is termed “spontaneous combustion”. On a more practical note, the relatively low AIT of diesel, which is, surprisingly, lower than petrol, means that diesel engines do not have to have a spark plug. The action of compressing

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the fuel/air mixture in the cylinders of the engine is enough to raise it above the AIT and cause ignition.

Fire Classifications Fires are commonly classified into five categories according to the fuel type. The classification also serves as the basis for identifying the means of extinguishing different types of fire. The fire categories are: 

Class A These are fires involving solid materials, normally of an organic nature, such as paper, wood, coal and natural fibres. These fires usually produce burning embers.



Class B These are fires involving flammable liquids or liquefied solids, such as petrol, oil, grease, fats and paint.



Class C These are fires involving gases or liquefied gases, such as methane, propane, and mains gas.



Class D These are fires where the fuel is a metal such as aluminium, sodium, potassium or magnesium.



Class F These are fires fuelled by cooking fats, such as in the case of chip pan fires.

Fires are generally classified within Classes A to D, with Class F and electrical fires added solely for the purposes of fire extinguisher selection.

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Fire Risk Assessment Fire Hazards and Assessment of Risk Background Primary responsibility for workplace fire safety is placed on employers and those in control of workplaces. They must assess and provide the measures necessary to prevent or control the risks from fire and, in particular, must ensure the following points: 

That the workplace is equipped with appropriate fire-fighting equipment, fire detectors and alarms and that any non-automatic fire-fighting equipment is easily accessible, simple to use and indicated by signs.



That appropriate measures are taken for fire-fighting, the nomination and training of employees to implement those measures, and the arranging of contacts with external emergency services.



That emergency routes are kept clear, and comply with specific criteria relating to routes, doors and signs.



That there is a suitable system of maintenance for fire precautions in relation to workplace procedures in general and to specific equipment and devices, which must be kept in good working order and repair.

The fire risk assessment is intended to serve as the basis for planning, and maintaining, all aspects of fire precaution in the workplace under a specific person charged with the responsibility of fire prevention.

Format for Risk Assessment A fire risk assessment should follow the recognised format for other risk assessments, i.e.: 

Identify the hazards – what are the likely sources of ignition including any processes carried out (e.g. hot work). In some workplaces, there may be other sources of oxygen (other than in the air). This may be in the form of bottled medical or industrial oxygen, or oxidising agents. What fuels are present, and how are they arranged and stored?



Identify who is at risk – in the event of a fire happening, the main risk is from the rapid spread of smoke and gases from the combustion process. It is necessary to determine whether there are adequate means of escape. This will necessitate making an assessment of the likely speed and spread of smoke, heat and gases; the number of people (including visitors) there are likely to be in the premises; how awareness is raised in case of a fire; and whether they can make a quick and simple escape.



Evaluate the risk – what are the chances of fire happening (likelihood) and if it does happen, what is the likely outcome (severity)? Are there works activities being carried out that increase the likelihood of fire? When carrying out this evaluation, it is necessary to consider the fire precautions that are already in place and determine if any increased fire precautions are necessary. These changes will then need to be implemented.



Record the findings – if there are five or more employees, then the significant findings should be recorded, including any persons found to be at particular risk.



Reviewing the risk assessment – to be carried out, for example, if there is significant change, after an incident or as part of an on-going health and safety plan.

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The risk assessment must be suitable and sufficient and allow suitable additional control measures to be introduced, where necessary.

Likely Sources of Ignition We considered likely sources of ignition earlier in this Study Unit. To recap here, sources of ignition include: 

Open flames - matches, welding torches.



Electrical sparking sources.



Overheating of surfaces due to excessive temperatures.



Hot surfaces – dryers.



Spontaneous ignition.



Sparks from grinding or tools.



Static electricity.



Friction.

Fuels That May Be Present Fuel consists of flammable materials that cover all states of matter. They include: 

Solids such as: wood, plastics, paper and wrapping and packaging materials, soft furnishings and fabrics and even metals, for example, magnesium.



Liquids such as: petroleum and its derivatives, paints, solvents, oils, etc.



Gases such as: hydrogen, LPG, methane and oxygen. Although oxygen is not strictly a flammable gas, oxygen enrichment can increase the flammability of a fuel.

Work Activities That Could Increase Risk Various activities in the workplace, both those directly related to the work being conducted and non-related activities can increase the risk of fire. Particular people may be at higher risk due to their activities at work, including, for instance, people who work: 

Near a furnace, for instance, or any sort of incinerator.



In the nuclear industry.



In the kitchens of a restaurant.



With chemicals.



With portable appliances.

Site Plan The location where workers carry out their activities may also affect their likelihood of being at risk. The risk assessment should include a detailed plan of the site, with all principal sources of ignition clearly marked. The plan should show all electrical appliances, heating plant, site of hazardous processes, location of the electric mains switches and the main gas control valves. It should also show waste disposal areas and the location of fire extinguishers and all site accommodation. It should also include the names and positions of responsible persons and their duties.

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In premises where much of the work is carried out within a single area, it may be adequate to carry out the assessment of a building as a single unit. However, in most cases, it will be necessary to subdivide the building into discrete areas or rooms. It is particularly important not to lose sight of the effects that adjacent work or storage areas, or some normally inaccessible areas, may have on the rest of the building – for example, in respect of roof voids, boiler rooms or fuel storage.

Fire Precautions in Place As part of the risk assessment, it is important to consider whether existing fire safety measures are suitable and sufficient. This would include considering: 

Control of ignition sources and sources of fuel.



Existence of fire detection and warning.



Means of escape.



Means of fighting fire.



Maintenance and testing of fire precautions.



Fire safety training of employees.

Changes Once the existing fire precautions have been evaluated, the risk assessment must consider whether any increased fire precautions are necessary, as well as how to go about implementing any changes. Improvements made will need to be maintained to ensure the ongoing safety of workers.

Recording and Review The result of the assessment, as well as actions to be taken, should be recorded. Similarly, the assessment should be revised if there are any significant changes or after a suitable period of time. Various aspects of the work should be considered, as all may increase the risk of fire, for example: 

General working policies: for instance, no smoking.



Specific working practices: for instance, the removal of waste on a more frequent basis, reducing the use of flammable substances where alternatives are available, using fixed electrical installations (as opposed to portable appliances), or use of flame-resistant material on scaffolding.



The physical condition of the premises: for instance, the sealing of any gaps around the pipe-work running between rooms.



Movement of people and transport.

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Systems for the Prevention, Detection and Control of Fire Means of Detection and Raising the Alarm In order to determine the most suitable type of detection/alarm system for a particular building, it is necessary to determine the type of occupancy and escape strategy. Where the escape strategy is based on simultaneous evacuation then activation of a manual call point or detector should cause all fire alarm sounders to operate. Where the escape strategy is based on phased evacuation, however, a staged alarm system might be more appropriate (i.e. one tone for alert, another for evacuate). This system is used extensively in large organisations, college and university campuses for example, where full evacuation is often not necessary. All buildings should have provision for detecting fire. Consideration has to be taken of whether the chosen method of alarm can be heard in all parts of the building (the toilets, for example). In some circumstances a rotary gong would be sufficient, whilst other buildings would need electrically operated fire alarms. The fire-warning signal must be distinct from other signals in use.

Design and Application of Fire Detection and Alarm Systems All workplaces must have arrangements for: 

Sounding an alarm in the event of fire.



Evacuating staff to safe fire assembly points using means of escape routes.



Fighting the fire.

Regular tests of an alarm system serve to check the circuits and to familiarise staff with the call note. Fitting fire doors to a building cuts down the distances over which call bells are heard, and may mean further bells should be fitted or noise levels raised. A fire alarm can be raised automatically by a detection system or manually by a person in the affected building. The means for this will generally be either manual or manual/electric, not forgetting that an alarm can always be raised by shouting.

Principal Components of Systems – Detection and Signalling A fire detector identifies one or more physical changes in the protected environment indicative of the development of a fire condition. Usually mounted on ceilings or in air ducts, detectors are activated in the main by smoke or heat/light radiation. Such conditions can be readily identified: 

After ignition has occurred and the invisible products of combustion are released.



When visible smoke is produced.



When the fire produces flame and a degree of illumination.



When the temperature in the vicinity of the fire rises rapidly or reaches a predetermined value.

The types of detector designed to operate at one of these particular stages are: 

Ionisation smoke detectors.



Optical detectors.

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

Radiation detectors.



Heat detectors.

The most common types of detector system in use at present are those actuated by smoke and those actuated by heat. The final choice is based on the risk to be protected and the individual circumstances of each case (see the following table).

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Automatic Fire Detectors Type

Suitability

Smoke Ionisation Sensitive in the early stages of a fire when smoke particles are small. Sensitivity tends to drop as particles grow in size.

Areas having a controlled environment, i.e. free from airborne dust, etc., and generally housing complex equipment of a high intrinsic value, e.g. computer installations.

Optical Most effective in situations where the protected risk is likely to give rise to dense smoke (i.e. large particles).

Normally used as point detectors but have been developed to form zone sampling systems by monitoring air samples drawn through tubes.

Radiation Infra-red Rapid detection because of almost instantaneous transmission of radiation to the detector head. This is dependent, however, on the detector having a clear ‘view’ of all parts of the protected area.

Warehouses or storage areas, etc. Detectors are available which can scan large open areas and will respond only to the distinctive flame flicker. Can be used to detect certain chemical fires. The ultra-violet detector tends to be used mainly for specialised purposes.

Ultra-violet As for infra-red. Heat Fusible alloys Alloys will need replacing each time detector operates.

Areas of general risk where vapour and particles are normally present. Cost is relatively low compared to other types of detectors.

Expansion of metal, air and liquid Generally self-resetting.

Both ‘fixed-temp’ and ‘rate-of-rise’ are equally efficient but ‘fixed-temperature’ types are preferred in areas where a rapid rise in temperature is a likely result of the normal work processes.

Electrical effect Not widely installed. Some specialist use. Note for all types of heat detectors May be used as point or line detectors and are designed to operate at a pre-selected temperature (‘fixed-temperature’ type) or on a rapid rise in temperature (‘rate-of-rise’ type) or both. With all heat detectors (particularly fixedtemp types), ‘thermal lag’ needs to be considered when choosing the operating temperature.

‘Rate-of-rise’ types will compensate for gradual rises in ambient temperature and are more efficient than the ‘fixed-temperature’ type in low-temperature situations. (‘Rate-of-rise’ detectors generally incorporate a fixedtemperature device.)

Not all detectors will be equally sensitive in every possible situation. In some cases a combination of different detectors may be required. Smoke and heat detectors are suitable for

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most buildings. Radiation detectors are particularly useful for high-roofed buildings, e.g. warehouses, and situations in which clean-burning flammable liquids are kept. Laser infra-red beam detectors appear to have advantages where there are tall compartments or long cable tunnels, for example. Such generalisations should be considered in conjunction with the nature of the risk to be protected in order to establish: 

The reliability required. A more robust detector is necessary in an industrial setting than is required for hotel purposes. Dusty or damp atmospheres will affect some detectors more than others.



The sensitivity required. It would obviously be undesirable to install a smoke detector set at high sensitivity in a normally crowded hotel bar (or similar conditions).



The location of detectors. The detectors should be located so they are in the best possible position to perform their function.

All alarm systems must be maintained and tested regularly, and the results recorded. Any faults discovered must be rectified and the system rechecked. All staff must know how to raise the alarm and what to do when the fire alarm sounds. Staff with hearing or other physical disabilities must be accommodated within an evacuation plan (e.g. people in wheelchairs cannot use stairs if a lift is inactivated). Emergency lights or vibrating devices may be used in addition to bells or sirens.

Manual and Automatic Alarm Systems Manual Systems Manual systems are suitable for small workplaces. The purely manual means for raising an alarm involve the use of the following basic devices: 

Rotary gongs that are sounded by turning a handle around the rim of the gong.



Hand strikers, e.g. iron triangles suspended from a wall accompanied by a metal bar that is used to strike the triangle.



Hand bells.



Whistles.



Air-horns.

These devices are normally found on the walls of corridors, entrance halls and staircase landings, in a situation where they are readily available to anyone who may need to raise an alarm. While they give an alarm over a limited area, operation of one of them is rarely adequate to give a general alarm throughout the premises. As a person is required to operate them, a continuous alarm cannot be guaranteed for as long as may be necessary.

Manual/Electric Systems These are systems which, although set in motion manually, operate as part of an electrical alarm circuit. The call points in a manual/electric system are invariably small wall-mounted boxes which are designed to operate either: 

Automatically, when the glass front is broken.



When the glass front is broken and the button pressed in.

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Most available models are designed to operate immediately the glass front is broken. In order to raise an alarm, it is possible to use facilities that may already be installed in a building for other purposes, e.g. a telephone or public address system. With automatic telephone systems, arrangements can be made for a particular dialling code to be reserved for reporting a fire to a person responsible for calling the emergency services and sounding the general alarm. Alternatively, it can be arranged that use of the code automatically sounds the general alarm.

Automatic Systems An automatic fire alarm system may be designed to respond to heat, smoke and the products of combustion and flames. The system will give warning of a fire, and some more elaborate designs do incorporate a facility for additional functions, such as activating water sprinkler systems, closing down ventilation, or air conditioning plant or activating automatic door releases.

When and How to Fight a Fire Extinguishing a fire is based on removing one or more sides of the fire triangle: •

Removing the Fuel Extinction by this process is known as starvation. This can be achieved by taking the fuel away from the fire, taking the fire away from the fuel and/or reducing the quantity or bulk of fuel available. Thus, materials may be moved away from the fire (to a distance sufficient to ensure that they will not be ignited by any continuing radiant heat) or a gas supply may be turned off.

•

Removing the Oxygen Extinction by this process is known as smothering. This can be achieved by either allowing the fire to consume all the available oxygen, whilst preventing the inward flow of any more oxygen, or adding an inert gas to the mixture. The most usual method of smothering is by use of a blanket of foam or a fire blanket.

•

Removing the Heat Extinction by this process is known as cooling. Cooling with water is the most common means of fighting a fire and this has a dual effect in terms of: absorbing heat and thereby reducing the heat input into the fire, and reducing the oxygen input through the blanketing effect of the steam produced.

Portable Fire-Fighting Equipment The main types of portable fire-fighting equipment are fire extinguishers. These are appliances designed to be carried to the point of the fire and operated by hand. They contain an extinguishing media that is expelled by internal pressure on operating the release mechanism and can be directed by means of a horn or tube onto the fire. The pressure may be by compression within the extinguisher or may be the result of a chemical reaction or release of gas from a cartridge, triggered by the operation of the extinguisher. The range of fire extinguishers (their size, colour, method of operation and claims for performance) is so great as to produce a considerable degree of confusion. The equipment that the average person will grab in the event of fire should be, according to the experts, suitably located and suitable for the risk. The problems arise when more than one type

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of risk may be encountered and the person, who is operating under pressure, is faced with a choice of extinguisher. It could well be that the wrong choice could render the efforts wasted or even expose the person to danger! Firstly, we will identify the nature of the risk and the choices of agent which are available. The Nature of Risk FIRE CLASS

DESCRIPTION

EXAMPLES

EXTINGUISHING AGENTS

A

Solid - carbonaceous-based

Wood, paper, fibres, rubber

Water, also foam, dry powders and CO2

B

Flammable liquids

Those miscible with water

Alcohol, acetone, methyl acetate

Dry powders, special foam, vaporising liquids, water, CO2

Liquefiable solids (greases, etc.)

Those immiscible with water

Petrol, diesel, oil, fats and waxes

Dry powder, foam, vaporising liquids, CO2

C

Gases and liquid gases

Natural gas, liquefied petroleum gases, e.g. butane, propane

Dry powder, carbon dioxide and foam

D

Flammable metals

Potassium, sodium, magnesium, titanium

Inert dry powder with special applicator, dry sand

F

Cooking oils and fats

Deep fat fryers

Wet chemical

Gas fires can be difficult to deal with. Whilst dry powder and carbon dioxide may be used to knock the flame down there is a risk of a build up of gas if it cannot be turned off. In some situations, it may be preferable to allow the fire to continue and to call the emergency services. You will notice that electrical fires are not listed; this is because electricity is not a fuel, it will not burn. However, it can cause fires and it can be present in fires so we have to take it into consideration when fighting fires.

Identification of Fire Extinguishers In order to identify the different types of fire extinguisher in some countries a colour coded systems is used, this indicates the type of extinguishant inside. Where a colour code systems is not in use it is essential that the extinguisher contents are easily identifiable

The following table shows typical colour coding for the common types of extinguishant. Colour Coding for Fire Extinguishants Fire extinguisher content

Colour of body or label/band

Water

Red

Foam

Cream

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Dry Powder

Blue

Carbon Dioxide

Black

Wet Chemical

Yellow

It should be noted that across EU member states new fire extinguishers will be red in colour but with an identifying band.

Siting of Extinguishers The correct type of extinguisher should be available for the risk it is going to protect against. The fire-fighting equipment should be sited in an easily seen and reached position, usually by an escape route. The location should be marked and should not be further than 30 metres from an alternative equipment location. The location should be: 

Conspicuous.



Readily visible on escape routes.



Properly mounted.



Accessible (less than 30 metres from any other fire extinguisher).



Near to the specific fire hazards

Other Types of Fire-Fighting Equipment Fire Blankets These are portable fire-fighting devices designed to smother a fire. There are a variety of fire blankets suitable for different types of fire – light-weight ones suitable for class A and B fires, and heavy duty blankets for industrial use, including those that can be used for class D fires. They are especially useful in a kitchen for extinguishing chip pan fires and other types of small fat and oil fires (class F). When using a fire blanket, the corners need to be turned towards you so that you do not get burnt as the blanket is laid over the fire. It should be kept in place until all the heat has been removed. Hose Reels These are very effective as a first line of attack against class A fires. Reels should be located near exits, stairways or lobbies and arranged so that no part of the building is beyond the reach of the jet (6 metres). If the hose reel is fitted into a recessed installation the doors, whether glazed or not, should bear the words “FIRE HOSE REEL” in red letters at least 50 millimetres high on a white background. The hose has a shut-off nozzle and the supply is via a control valve at the connection to the main, which must be opened before the reel is pulled out. Some reels operate this valve automatically as the hose is rolled out. Reel installations have a number of advantages: 

Only the required length of hose has to be run out.



The hose is light and only one person is required to operate it.

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

The lack of back pressure from the nozzle makes it easy for persons of limited strength to handle it.



The control of the water at the nozzle of a hose reel will limit water damage.

Automatic Sprinklers There are several different types of sprinkler system, but essentially they all involve fixed pipe work in the ceiling of each part of the protected building. The pipe work is connected via control valves to a water supply and sprinklers are spaced at intervals along the pipe work so that the discharge patterns overlap and leave no part unprotected. They are activated by automatic fire detectors. The quantity of water discharged is designed to at least control any fire in the protected area, if not to extinguish it. Drenchers These are designed to provide a coverage of water over areas of a building or structure which could be damaged by radiant heat from a fire in close proximity. Normally adequate spacing limits the radiation hazard and, therefore, only vulnerable areas need be covered, such as unprotected doors and windows. Hydrants and Foam Inlets These are provided on the outside of buildings to allow the emergency services easy access to a supply of water or foam close to a potential fire hazard, with the type of extinguishing agent being appropriate to the type of hazard.

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How to Establish Means of Escape from Fire General Principles An integral part of any fire safety programme is the consideration and implementation of suitable means of escape. The “Means” will vary dependant on a number of factors which may differ from premises to premises. A standard factor in all premises however is the time it will take for people to safely evacuate from a burning building and to reach a place of safety; which in turn is largely dependant on: 

The number and types of people needing to escape.



Widths and capacity of escape routes and stairways.



The time available for people to escape to a place of safety.



The distances that have to be travelled to reach that place in that time.

Travel distances are provided as guidance for various levels of risk and are useful in helping to determine if for example, the numbers of fire exits are sufficient or the layout of the workplace is suitable. Suggested travel distances are: Escape Routes

Suggested Range of travel distance

Where more than one escape route is provided

45m in normal fire-risk areas

Where only a single escape route is provided

18m in normal fire-risk areas

If the fire risk is more or less than the guidelines shown then the travel distances would need to be adjusted. When assessing travel distances you must consider the distance to be travelled, allowing for walking around furniture etc and should be measured from the furthest point to the nearest place of reasonable safety which is: 

a protected stairway enclosure



a separate fire compartment from which there is a final exit to a place of safety



the nearest available fire exit

Protection of Escape Routes A protected route may consist of two interlinked structural components: (a)

A protected corridor (horizontal movement).

(b)

A protected stairway (vertical movement).

The principle to follow is that once people enter either (a) or (b) they should normally be able to proceed to a place of safety without leaving the protected route. The protection required at (a) and (b) is generally achieved by ensuring that the protected area has at least 30 minutes’ fire resistance.

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Emergency Lighting Emergency (or safety) lighting should be provided where failure of the normal system would cause problems, e.g. in buildings used after dark, or darkened, e.g. cinemas, hospitals, and sections of buildings used for means of escape. The purposes of emergency lighting are: 

To identify the escape route.



To provide illumination along the route.



To ensure that alarm call points and fire-fighting equipment can be easily located.

Emergency escape lighting should be provided in those parts of buildings where there is underground or windowless accommodation, core stairways or extensive internal corridors. Generally the need for such lighting will arise more frequently in shops than in factories and offices because of the greater likelihood of people in the building being unfamiliar with the means of escape. Emergency lighting is only designed to ensure that people can find their way out of a building, and so the light requirement is much lower than for normal use. The level of emergency illumination should be related to the level of normal illumination to avoid panic whilst eyes adapt to the reduced light.

Signs/ Notices It is commonly expected that emergency signs are square or rectangular with a green background and white symbols. The ‘running man’ sign (see the figure that follows) usually appear over all fire escape exits, and the ‘door and arrow’ sign is used to mark escape routes. To ensure that speakers of all languages are able to understand the signage it is advisable, where possible, not to use words.

Emergency Exit/Escape Route Signs

Disabled Persons Provision needs to be made for means of escape for disabled persons to ensure the safe evacuation of disabled persons from the workplace in a fire situation,. This may include: 

Means of communication with people with a hearing disability must be considered. Alarms using sound cannot be relied in such a case. Such means could include:

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−

Face-to-face communication.

−

Equipment such as: induction loops, textphone, TV subtexting, amplifiers, flashing lights.



When people may be asleep, special consideration must be given as to how they would be woken in case of emergency.



Floor surfaces should be even, non-slippery and free from obstacles to aid visually impaired people and wheelchair-users.



Sufficient space and time should be allowed for wheelchair-users when planning escape routes, including width of corridors and doors.



Means of communication with visually impaired people must be considered. This could include: taped messages, tactile surfaces and audible instructions.



Unlike normal passenger lifts, which are usually made inaccessible in the event of fire, it is essential that a lift that may be used to evacuate disabled people can still be operated safely if there is a fire in the building, as this may be the disabled person’s main means of escape.



Refuges: −

As disabled people will often need others to assist them to evacuate from a place of work, a refuge provides a temporary, safe area for disabled people to wait. The area should be both separated from the fire by fire-resisting construction, and provide access via a safe route to a storey exit.

−

As wheelchairs may well be used by disabled workers, the refuge should be big enough to allow wheelchair use and manoeuvrability within the space without difficulty. It is also essential that the location of any wheelchair spaces within refuges does not affect the means of escape for other people.

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Fire Emergency Arrangements General Evacuation Procedures With any building in which a great number of people are present the procedure must not allow panic as it will slow evacuation and may cost lives. The evacuation must be orderly and handled in such a manner that the escape facilities, e.g. capacity of escape routes, can handle the numbers of people using them. Typical duties of staff members in fire situations would include: 

Members of staff detailed to shepherd the public to the escape route.



Senior members of staff search all the floors, WCs, etc.



Members of staff keep exits open and clear.



A responsible member should meet the brigade on arrival and inform them of all relevant details.



On leaving the premises ensure all doors and windows are closed.

As soon as the premises have been evacuated and all personnel are assembled in their prearranged safe areas, fire wardens or other appointed persons must account for people – often done by carrying out a roll call on the basis of a continually updated register (the compilation of which will be a line management function). The roll must include staff, visitors, contractors, etc. If anyone is not accounted for, the Fire Officer in charge must be notified as soon as the Fire Services arrive. In the case of premises where there is random public access (shops, etc.), it may be necessary for the Fire Services to undertake a search.

Functions of Fire Wardens and Fire Marshals Whatever the number of employees, it is vital that responsibility for action in the event of fire is assigned to specific persons. All premises should have designated and trained fire marshals or fire wardens who are responsible for the following actions: 

Ensuring all members of staff (and other persons on the premises, including the general public in the case of shops and public buildings) leave by the designated escape route.



Searching all areas, including toilets, to ensure that the area is clear.



Ensuring that fire escape routes are kept open and clear at all times.



Ensuring all doors and windows are closed on leaving the area.



Conducting the roll call at the assembly area.



Meeting the emergency services on arrival and informing them of all relevant details.

In addition, premises with a large number of occupants or where there is a high fire risk may have trained personnel who will carry out first-aid and fire-fighting. They will also have a nominated senior person – for example, a safety officer or senior manager – who is responsible for all aspects of fire safety including training, overseeing of fire contracts (such as for equipment maintenance) and record-keeping.

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Deputies should be nominated to take over all these responsibilities when the marshal/warden or senior person is absent.

Post-Evacuation Debrief After any ‘real’ or pre-planned fire evacuation, it is essential that the management review the event to learn lessons for the future. For this to happen effectively, fire marshals, wardens and any others involved in the event should be de-briefed. The event should then be analysed for strengths and weaknesses, and actions for improvement identified. Feedback on the event and the identified improvements must be provided to all involved personnel. These de-briefs should be recorded to demonstrate best practise – and may be a requirement of the Fire Certificate.

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Principles of Fire Safety Training Extinguisher Training The ability to carry out fire-fighting with portable extinguishers may not only control the rate at which a fire spreads, thereby giving those precious few moments which mean the difference between a person escaping or becoming a victim, but often reduces fire damage to a lower level than would have been the case if the fire had proceeded without being checked. It is, therefore, very important that all personnel are familiar with the available fire-fighting equipment and are able to use it correctly. The following points form a general scheme for training in the use of fire-fighting equipment: 

General understanding of how extinguishers and other appliances operate.



The importance of using the correct extinguisher for different classes of fire (which should not be a problem as only the correct type of extinguisher should be available for use in any particular situation). Staff should be aware that using the wrong type of extinguishing agent on a fire may increase its intensity.



Recognition of whether the extinguisher has to be used in the upright position or in the upside-down position.



Practice in the use of different extinguishers. This can be done with or without a practice fire, although dealing with a live fire is obviously the better method. Opportunities for training may arise during the inspection process – when appliances are being tested or discharged. (Training in using carbon dioxide extinguishers is particularly important as they can be frightening to use – they start off with a bang and the horn gets freezing and can cause the skin to adhere to it, pulling the skin off if you try to remove your hand. Users should angle the CO2 horn into position before they activate the fire extinguisher. They should ensure that they do not touch or hold the horn during or immediately after operating it.)



When to and when not to tackle a fire. If the fire is small and has not involved the building structure, then portable extinguishers can generally be used. It must be understood that extinguishers can only provide a ‘first-aid’ treatment and evacuating the building must take precedence over fighting a fire if the conditions demand it. A means of escape must always be maintained.



When to leave a fire that has not been extinguished. As a general rule, once two extinguishers have been discharged, the fire requires the Fire Service. When leaving an unextinguished fire, all doors and windows should be closed to help contain the fire.

Evacuation Procedure Training in fire safety procedures is necessary for everybody. It is essential that key personnel who are responsible for implementing safety procedures are given adequate training in order to perform their duties. The skill is in identifying the level of training required. This can range from induction training for new employees, to more specialised training for members of staff with specific safety responsibilities; for example, fire wardens and people dealing with specialist processes or equipment. Training must be monitored and updated as necessary (e.g. when circumstances change in premises or staffing) and should be modified to suit individual requirements. Keeping records of the training given to individuals will not only ensure that all employees are made aware of their responsibilities, it also provides proof of provision of adequate training.

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The records will also be invaluable in dealing with investigations of any incidents or accidents. Carrying out and recording the results of regular risk assessments can also help identify training needs. Training should be specific to the particular premises and all staff should receive training at sufficiently regular intervals to ensure that existing members of staff are reminded of the action to take, and that new staff are made aware of the fire routine for the premises. Training should be given at least once in each period of 12 months; but in some circumstances where there is high turnover of staff, or where there is a high fire risk, or material changes which significantly affect the fire safety arrangements, training may have to be more frequent. Instruction and training should be based on written procedures and should be appropriate to the duties and responsibilities of the staff. It is particularly important that all staff (including those casually employed) should be shown the means of escape and told about the fire routine as soon as possible after they start work. It is also necessary to ensure that occasional workers, those on shift duties and others who work in the premises are similarly instructed. Special consideration should be given to any employees with language difficulties or with any disabilities that may impede their understanding of the information. Instruction should be given by a competent person and the following topics, where appropriate, should be covered in each training session with practical exercises where possible: 

Action to take on discovering a fire.



How to raise the alarm and the procedures this sets in motion.



Action to be taken upon hearing the fire alarm.



Procedures for alerting members of the public including, where appropriate, directing them to exits.



Arrangements for calling the emergency services.



Evacuation procedure for the premises to an assembly point at a place of safety.



Location and use of fire-fighting equipment.



Location of escape routes, including those not in regular use.



How to open all escape doors.



The importance of keeping fire doors closed.



How to stop machines and processes and isolate power supplies where appropriate.



The reason for not using lifts (other than those specifically provided or adapted for use by people with disabilities in accordance with BS 5588: Part 8).



The importance of general fire precautions and good housekeeping.

A fire drill should be carried out at least once and preferably twice a year simulating conditions in which one or more of the escape routes from the building is obstructed. During the drills the fire alarm should be operated by a member of staff who is told of the supposed outbreak, and thereafter the fire routine should be rehearsed as fully as circumstances allow. The training and instruction given should be recorded in a log or other suitable record, which should be available for inspection. The following are examples of matters that should be included in a fire record-keeping book: 

Date of the instruction or exercise.

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

Its duration.



Name of the person giving the instruction.



Names of the persons receiving the instruction.

On all premises, one person should be responsible for organising fire instruction and training, and in larger premises a person or persons should be nominated to co-ordinate the actions of the occupants in the event of a fire. Printed notices should be displayed at conspicuous positions in the building stating in concise terms the action to be taken upon discovering a fire or on hearing the fire alarm. The notices should be permanently fixed in position and suitably protected to prevent loss or defacement. Written instructions may be supplemented by advice in pictogram form.

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Title

Page

Explosion

TYPES AND PRINCIPLES OF EXPLOSION ............................................................................................................ 3 VAPOUR PHASE EXPLOSIONS ..................................................................................................................................... 3 DEFLAGRATIONS .................................................................................................................................................... 3 DETONATIONS....................................................................................................................................................... 3 BOILING LIQUID EXPANDING VAPOUR EXPLOSION (BLEVE) ................................................................................................ 4 CONFINED/UNCONFINED VAPOUR CLOUD EXPLOSION (CVCE/UVCE) .................................................................................... 5 DUST EXPLOSIONS ................................................................................................................................................. 6 PRIMARY AND SECONDARY EXPLOSION ......................................................................................................................... 6 ASSESSING AND CONTROLLING EXPLOSION RISKS .......................................................................................... 8 RISK ASSESSMENT PRINCIPLES ................................................................................................................................... 8 RISK CONTROL PRINCIPLES – HIERARCHY OF CONTROL ..................................................................................................... 9 EQUIPMENT FOR USE IN POTENTIALLY EXPLOSIVE ATMOSPHERES........................................................................................ 10 CLASSIFYING EXPLOSIVE ATMOSPHERES ...................................................................................................................... 11


BSC International Diploma | Unit 1 Element 1B: Applied Health and Safety Management Study Unit 1B2 | Explosion Learning Outcomes When you have worked through this Study Unit, you will be able to:

1.B.2.1 Explain the principles of explosion 1.B.2.2 Outline the principles of risk assessment and risk control in relation to explosion

Unit 1:

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Types and Principles of Explosion Vapour Phase Explosions An explosion is a sudden and violent release of energy, causing a pressure blast wave. Usually it is the result, not the cause, of a sudden release of gas under high pressure, but the presence of a gas is not necessary for an explosion. An explosion may occur from a physical or mechanical change or from a chemical reaction. An explosion can occur without fire, such as the failure through over-pressure of a steam boiler or an air receiver. In discussing the explosion of a flammable mixture, we must distinguish between detonation and deflagration. If a mixture detonates, the reaction zone propagates at supersonic velocity and the principal heating mechanism of the mixture is shock compression. In a deflagration, the combustion process is the same as in the normal burning of a gas mixture; the combustion zone propagates at subsonic velocity and the pressure build-up is slow. Whether detonation or deflagration occurs in a gas-air mixture depends on various factors, including the concentration of the mixture and the source of ignition. Unless confined or ignited by a high-intensity source (a detonator), most materials will not detonate. However, the pressure wave (blast wave) caused by a deflagration can still cause considerable damage. Certain materials, such as acetylene, can decompose explosively in the absence of oxygen and are thus particularly hazardous.

Deflagrations A deflagration is the very rapid auto-combustion of particles of explosive as a surface phenomenon. It may be initiated by contact with a flame or spark, and may be caused by impact or friction. Deflagration is a characteristic of low explosives. Exothermic reactions can lead to high temperatures and, in the case of large fires, to extensive loss of property and severe damage from radiant energy. However, in many plant accidents it is the sudden generation of pressure that leads to severe damage, injury and deaths. So it can be said that pressure blows up plants, not temperature. Of course, temperature and pressure are closely related, but it is the pressure effect that concerns us here. Deflagration is a reaction which propagates to the unreacted material at a speed less than the speed of sound in the unreacted substance. The conditions for a deflagration to occur are that the gas mixture is within the flammable range and that there is a source of ignition or that the mixture is heated to its auto-ignition temperature. In the absence of explosion relief, the deflagration explosion of a hydrocarbon-air mixture is easily capable of bursting a vessel if it is operating near its design pressure when the deflagration takes place. For reactions operating at or near atmospheric pressure, such as many drying and solids processing operations, it may be practical to construct facilities that will withstand the maximum explosion pressure of most dust-air and flammable gas-air mixtures.

Detonations A detonation is the extremely rapid, self-propagating decomposition of an explosive accompanied by a high pressure-temperature wave that can move at 1,000-9,000 m/s. It may be initiated by mechanical impact, friction or heat. Detonation is a characteristic of high explosives, which vary considerably in their sensitivity to shock. A detonation is a reaction that propagates to unreacted material at a speed greater than the speed of sound in the unreacted material; it is accompanied by a shock wave and extremely

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high pressures for a very short time. It is debatable whether the flammable range is the same as the detonable range. Detonation limits are normally reported to be within the flammable limits, but it is widely held that separate detonation limits do not exist. Detonation of a gas-air mixture may occur by direct initiation of detonation by a powerful ignition source, or by transition from deflagration. This transition is much more likely to occur in pipelines than in vessels. Two useful rules are: 

Almost any flammable gas mixture is detonable if initiated with a sufficiently energetic source.



Detonation of a gas-air mixture is possible in pipelines but is unlikely in vessels.

With a flammable mixture of gases burning in a pipe with one end closed, a series of pressure waves travelling at the speed of sound moves through the unburnt gas. Later waves travelling through the unburnt gas, which has been heated by compression from the earlier waves, speed up because of the higher temperature and overtake the first wave, and a shock wave develops. Flame then follows the shock wave and catches up with it, forming a detonation wave. A stable detonation wave may develop, which moves with supersonic speed relative to the unburnt mixture, and peak incident (side-on) pressures can be of the order of 30 times the initial absolute pressure.

Boiling Liquid Expanding Vapour Explosion (BLEVE) A BLEVE involves a sudden release of vapour, containing liquid droplets, owing to the failure of a storage vessel. This occurs when a pressure vessel containing liquid is heated so that the metal loses strength and ruptures, typically, as a result of exposure to fire. The failure is usually in the metal in contact with the vapour phase; the metal in this area heats to a higher temperature because there is no liquid heat sink to keep its temperature from rising rapidly, as there is where metal contacts a liquid phase. A BLEVE can occur with both flammable and non-flammable materials (e.g. water). The initial explosion may generate a blast wave and missiles. If the material is flammable, it may cause a fire or may form a vapour cloud that then gives rise to a secondary explosion and fireball. The best-known type of BLEVE involves LPG (liquefied petroleum gas). Once a fire impinges on the shell above the liquid level, the vessel usually fails within 10 to 20 minutes. In the case of a BLEVE involving a flammable material, the major consequences are, in decreasing order of importance: 

Thermal radiation from the resultant fireball.



Fragments produced when the vessel fails.



Blast wave produced by the expanding vapour liquid.

For example, a BLEVE of a propane sphere of diameter 15 m could cause damage as far away as 4,500 m, and radiation damage and fragmentation damage would each extend to about 1,000 m. Significant damage to equipment and buildings from radiation is possible from a BLEVE. Wooden structures may be ignited if the radiant heat density at the structure's location exceeds the threshold value for ignition of wood. Severe damage from fragmentation can be expected in the area where 50% or more of the fragments may fall (typically about 100 m from the vessel). As mentioned above, in a fire, a tank containing liquid is most vulnerable in the area controlling the vapour, because very little heat can be absorbed by the vapour, so the metal

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here will heat up rapidly and weaken. The metal contacting the liquid will heat up much more slowly. There is, therefore, a dilemma in that a BLEVE may occur sooner in a partly full vessel than a full one, but a full vessel will contain more fuel for the resulting fireball and fire than will a partly empty vessel.

Confined/Unconfined Vapour Cloud Explosion (CVCE/UVCE) Confined If a flammable vapour cloud is ignited in a container, e.g. a process vessel, or in a building - so that it is confined - pressure can build up until the containing walls rupture. This is a Confined Vapour Cloud Explosion (CVCE), as with natural gas explosions in buildings. A relatively small amount of flammable material, a few kilograms, can lead to an explosion when released into the confined space of a building. CVCEs can cause considerable damage, e.g. peak over-pressures of up to 8 bars can be experienced in a fully confined explosion, and much higher in the unlikely event of a detonation, but in general they have insufficient energy to produce more than localised effects as far as off-site damage is concerned (e.g. broken windows). Much of the major damage found within the confines of the cloud following a UVCE (see next section) probably results from local CVCEs. If the results of a CVCE affect nearby plant or equipment, serious secondary explosions can follow. For personnel close to the blast, missiles and flash-burns can result in serious or fatal injuries. For instance, fatalities have occurred from explosions during hot work on inadequately cleaned/purged 45-gallon drums that had contained flammable residues, or in natural gas or LPG explosions following leaks into rooms. Unconfined An Unconfined Vapour Cloud Explosion (UVCE) results from the release of a considerable quantity of flammable gas or vapour into the atmosphere, and its subsequent ignition. Such an explosion can cause extensive damage, such as occurred at Flixborough in the UK. When a large amount of volatile material is released rapidly into the atmosphere, a vapour cloud forms and disperses. If the cloud is ignited before it is diluted below its lower flammable limit, an unconfined (or uncontrolled) vapour cloud explosion will occur. This is one of the most serious hazards in the process industries. Both shock waves and thermal radiation will result from the explosion; the shock waves will usually produce the greater damage. The energy of the blast wave is generally only a small fraction of the energy available from the combustion of all the material that constitutes the cloud. The ratio of the actual energy released to that available is often called the explosion efficiency. Unconfined vapour clouds can deflagrate or detonate, but a deflagration is much more likely. A detonation is more destructive, but a deflagration can produce a damaging pressure wave. Deflagration occurs when the advancing flame front travels subsonically, in most cases <10 m/s. Detonation occurs from less common supersonic advancement of flame fronts. If a flammable mixture may be present in process equipment, precautions should be taken to eliminate ignition sources. However, it is prudent to assume that, despite these efforts, a source of ignition will at some time occur. A UVCE requires a rapid release of a flammable liquid, moderate dispersion to produce a very large flammable air and hydrocarbon cloud, and usually some degree of containment. A minimum of 5 tonnes of vapour is probably necessary; hence UVCEs are rare events.

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Dust Explosions Factors of Importance Some dusts are capable of producing explosions that are every bit as destructive as those from gases or vapours. Most organic solids, most metals, and some combustible inorganic salts can form explosive dust clouds. The dust must be explosible. (The ignition energy can be determined experimentally in test apparatus.) Other factors that affect the possibility of dust explosions are discussed here. Particulate Size The dust particles must be of a suitable size. Solids do not have the divisions of flammability that liquids do. Dusts, however, are finely divided solids and, as with sprays, they have an increased surface area. Generally, finer dusts are more hazardous. The fineness and composition of the dust may also be a factor in determining whether it is explosible, and it is this particle size that we must consider. The smaller the particle, the greater will be the total exposed surface area of a given mass. The result of putting a source of ignition to a concentration of airborne dust can be the same as discussed with atomised fuel, with very rapid burning. Explosive Concentrations The dust must be mixed with air and have a concentration which lies between the explosive limits: 

The lower explosive limit is generally taken to be about 25 g to 50 g per cubic metre of air and a cloud will obscure visibility to about one metre - such a concentration would not normally be encountered in the workplace (contravening the COSHH Regulations, if nothing else). A dust cloud will have variable density and tends to become finer over time as the heavier particles settle out.



The upper explosive limit is ill-defined but generally taken to be about ten times the lower one.

Ignition Energy There must be a sufficient source of energy to ignite the dust cloud. It is a fact that explosible dust clouds can be ignited by sparks from electrical equipment such as switches and motors, and in short-circuiting caused by damaged cables. Additionally, electrostatic discharges may initiate dust explosions in industry. For an assessment of the hazard situation in dustprocessing installations, knowledge of the minimum ignition energy is indispensable. The minimum ignition energy (MIE) of a dust cloud is the lowest energy value of a highvoltage capacitor discharge required to ignite the most readily ignitable dust/air mixture at atmospheric pressure and room temperature. The dust concentration and the ignition delay are systematically varied until a minimum value of the ignition energy is found. The tested energy levels are 1,000, 300, 100, 30, 10, 3 and 1 mJ.

Primary and Secondary Explosion The concentrations needed for a dust explosion do not usually occur outside of process vessels, hence most severe dust explosions start within a piece of equipment (such as mills, mixers, dryers, cyclones, hoppers, silos, etc.). These are known as Primary Explosions. During processes dust is generally suspended in air in process equipment that can allow dust explosion conditions to occur. This explosion can cause the vessel to rupture.

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Secondary Explosions are caused when lying dust in the workplace is disturbed by the primary explosion and forms a second dust cloud that is then ignited by the heat released from the primary explosion. The problem is that small amounts of lying dust occupy very little space, but once disturbed can easily form dangerous clouds. A 1 mm layer of dust can give rise to a 5 m deep cloud of dust. There can be a large series of explosions triggered in this manner, with devastating consequences if there is a lot of lying dust that is disturbed. It is important, therefore, to reduce the amount of lying dust to a minimum.

Pressure Systems Explosions A pressure system is a means of storing and transporting energy for use in the workplace. Hazards that the safety practitioner should be aware of stem from the use or misuse of this energy and from the possible failure of the system. The violence of a pressure explosion is measured by the rate of pressure rise (RPR). The RPR is dictated by temperatures reached during combustion and in a confined space, the RPR is significantly higher than for unconfined spaces due to pressures inside the vessel being above atmospheric.

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Assessing and Controlling Explosion Risks Risk Assessment Principles Where a dangerous substance is or is liable to be present at the workplace, the employer must make a suitable and sufficient assessment of the risks to his employees which arise from the substance. The main considerations for the assessment of risks will include: 

Finding out what dangerous substances and processes are in the workplace and what the fire and explosion risks are. This will often require research of relevant safety data sheets for such information as classification and hazards identification, flash and boiling point, reactivity, stability and volatility. Employers may also need also to consult with other bodies such as industry specialists and trade organisations in order to properly assess the risks of explosion occurring.



Identify and classify areas (Zones) of the workplace where explosive atmospheres may occur in those areas. The determination of whether explosive atmospheres exist will often be based on environmental monitoring to determine the presence and concentration of airborne substances.



Identify all potential sources of ignition from within the applicable zones.

The risk assessment should take into account: 

The hazardous properties of the substances.



Information provided on safety provided by the supplier, including information contained in any relevant safety data sheet.



The circumstances of the work including: −

The work processes and substances used and their possible interactions.

−

The amount of the substance involved.

−

Where the work will involve more than one dangerous substance, the risk presented by such substances in combination: and

−

the arrangements for the safe handling, storage and transport of dangerous substances and of waste containing dangerous substances.



Activities, such as maintenance, where there is the potential for a high level of risk.



The effect of measures which have been or will be taken pursuant to these regulations.



The likelihood of hazardous explosive atmospheres occurring and the scale of the anticipated fire or explosion.



The likelihood that ignition sources, including electrostatic discharges, will be present and become active and effective.



Those at risk including employees, contractors, others sharing or visiting the premises, members of the public.



Any places which are or can be connected via openings to places in which explosive atmospheres may occur.



Other additional information which may be needed by the employer in order to complete the assessment.

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The risk assessment will assist in determining whether the existing measures are suitable and sufficient, and whether additional controls are necessary. The necessary measures that are identified in the risk assessment must be put into place before the work starts. The risk assessment is an identification and careful examination of the explosive atmospheres present or liable to be present in the workplace. A record of the significant findings must be made in a readily retrievable format and the assessment must be reviewed regularly and specifically if the employer suspects that it is no longer valid. An Explosive Atmosphere is defined as a mixture, under atmospheric conditions, of air and one or more dangerous substances in the form of gases, vapours, mists or dusts in which, after ignition has occurred, combustion spreads to the entire unburned mixture.

Risk Control Principles – Hierarchy of Control Elimination or Reduction of the risks Employers must put control measures in place to eliminate risks from dangerous substances, or reduce them as far as is reasonably practicable. Where it is not possible to eliminate the risk completely employers must take measures to control risks and reduce the severity (mitigate) the effects of any fire or explosion.

Control measure hierarchy 

Substituting the dangerous substance with a substance or process that eliminates the risk.



Reducing the quantity of dangerous substance to a minimum.



Avoid or minimise releases.



Control releases at sources.



Prevent the formation of an explosive atmosphere.



Collect, contain and remove any releases to a safe place, for example, by ventilation.



Avoid ignition sources.



Avoid adverse conditions that could lead to danger.



Keep incompatible substances apart.

Information, instruction and training Employees and others at work where dangerous substances are present must be given suitable information, instruction and training on the substances, hazards and risks they may be exposed to. This will include reference to the risk assessment findings, precautions and actions taken. It will typically include reference to: 

Identity and location of any dangerous substance.



Type and extent of risks.



Significant findings of the risk assessment.



The control and mitigation measures adopted.

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Information must also be given to co-occupants of shared premises, sufficient to enable other employers to inform their own staff about the safeguards and procedures required.

Mitigation involves putting in place measures to reduce the effects of any explosion-related incidents and to prepare plans and procedures to deal with explosions. Measures should be implemented that are consistent with the risk assessment and appropriate to the nature of the activities. This may include preventing fires and explosions from spreading to other parts of the workplace, reducing the number of employees exposed and providing plant and equipment capable containing or suppressing an explosion, or venting it to a safe place. Employees must be properly informed about and trained to control or deal with the risks from the dangerous substances. Arrangements for dealing with accidents, incidents and emergencies Employers must make arrangements to deal with serious or imminent danger and to protect people from the effects of any explosion. Arrangements might include: 

First aid facilities.



Safety drills.



Provision of information.



Suitable warning systems.



Escape facilities.



Personal protection and specialised safety equipment.

Equipment for use in Potentially Explosive Atmospheres A European Directive – ‘Equipment and Protective Systems intended for use in Potentially Explosive Atmospheres’ (ATEX) Directive 94/9/EC was introduced to provide control over the use of equipment in explosive atmospheres. The Directive applies to both electrical and mechanical equipment and protective systems intended for use in potentially explosive atmospheres. These include: 

equipment and protective systems for use within potentially explosive atmospheres;



devices for use outside potentially explosive atmospheres, but which are required for, or contribute to the safe functioning of equipment and protective systems located inside such atmospheres; and



components relating to the above.

The Directive has been implemented in Great Britain by The Equipment and Protective Systems Intended for Use in Potentially Explosive Atmospheres Regulations (SI 1996 No.192) which came into force on 1 March 1996 which were amended by the Equipment and Protective Systems Intended for Use in Potentially Explosive Atmospheres (Amendment) Regulations 2001 (SI 2001 No.3766) which came into force on 21 December 2001. International students may benefit from researching this information.

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Classifying Explosive Atmospheres Where explosive atmospheres may occur (intentionally or unintentionally) employers should ensure that: 

Areas where hazardous explosive atmospheres may occur are classified into zones based on their likelihood and persistence.



Areas classified into zones are protected from sources of ignition by selecting safe equipment and protective systems.



Where necessary, classified zones are marked with an “ex” sign at the point of entry.



Employees working in the zones are provided with the appropriate clothing to prevent the risk of an electrostatic discharge igniting the explosive atmosphere.



Areas where hazardous explosive atmospheres may be present are confirmed as being safe by a competent person before any operations commence.

Hazardous areas are classified in terms of zones on the basis of the frequency and duration of the occurrence of an explosive atmosphere. For gases, vapours and mists the zone classifications are: Zone 0 – An explosive atmosphere is present continuously or for long periods or frequently. Zone 1 - An explosive atmosphere is likely to occur in normal operation occasionally. Zone 2 - An explosive atmosphere is not likely to occur in normal operation, but if it does occur, will persist for a short period only.

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Title

Page

Major Accident Hazards

MAJOR ACCIDENT HAZARDS .............................................................................................................................. 3 BACKGROUND ....................................................................................................................................................... 3 NUCLEAR INDUSTRY................................................................................................................................................ 3 RAILWAY INDUSTRY ................................................................................................................................................ 3 CHEMICAL INDUSTRY .............................................................................................................................................. 3 CONTROLLING MAJOR ACCIDENT HAZARDS ...................................................................................................... 5 SCOPE OF RESPONSIBILITY ....................................................................................................................................... 5 GENERAL RESPONSIBILITIES ...................................................................................................................................... 5 MAJOR ACCIDENT PREVENTION POLICY (MAPP) ............................................................................................................. 5 SAFETY REPORT .................................................................................................................................................... 8 ON-SITE EMERGENCY PLAN ....................................................................................................................................... 9 OFF-SITE EMERGENCY PLAN ...................................................................................................................................... 9 PROVISION OF INFORMATION TO THE PUBLIC ................................................................................................................. 9 PROVISION OF INFORMATION TO OTHER ESTABLISHMENTS ............................................................................................... 10

BSC International Diploma - Element 1B | Applied Health and Safety Management

BSC International Diploma | Unit 1 Element 1B: Applied Health and Safety Management Study Unit 1B3 | Major Accident Hazards Learning Outcomes When you have worked through this Study Unit, you will be able to:

1.B.3.1 Describe the nature of major hazard industries 1.B.3.2 Describe and explain the principles of control relating to major accident hazards

Unit 3:

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Major Accident Hazards Background It has been recognised for many years that certain industrial activities have the potential to cause catastrophic consequences as a result of failure, and there have been a great number of high profile industrial accidents over the years which have caused massive devastation involving destruction of plant and facilities, loss of human life, environmental pollution and short and long term effects from the release of harmful substances into the atmosphere. These days, industries around the world presenting major hazards are very well regulated and follow strict control regimes. Here we will briefly discuss a few such high hazard industries and high profile accidents that resulted from failure of control systems:

Nuclear Industry On 25-26 April, 1986 the World's worst nuclear power accident occurred at Chernobyl in the former USSR (now Ukraine). The Chernobyl nuclear power plant located 80 miles north of Kiev had 4 reactors and while testing reactor number 4 numerous safety procedures were disregarded. At 1:23am the chain reaction in the reactor became out of control creating explosions and a fireball which blew off the reactor's heavy steel and concrete lid. The Chernobyl accident killed more than 30 people immediately, and as a result of the high radiation levels in the surrounding 20-mile radius, 135,000 people had to be evacuated. The nuclear industry is a diverse major hazards industry with a legacy of nuclear technology development that currently contributes to much of the world’s electricity needs.

Railway Industry There have been many rail disasters over the years, some leading to multiple fatalities. In September 1997 a high speed train ran into an empty freight train near Southall in the UK claiming seven lives. An inquiry report published in February 2000 put the immediate responsibility for the crash on the driver for going through two red lights. But it was also highly critical of Great Western Trains (GWT) because, due to a fault, the in-cab automatic warning system (AWS) was not working. This system could have prevented the danger signals being passed. The report spoke of "serious and reprehensible failures" of communication within GWT which led to the Swansea to London express making its journey with no functioning AWS.

Chemical Industry In 1974 a disastrous explosion occurred at the Nypro (UK) chemical plant in Flixborough in the UK. Five days before the accident a vertical crack had been discovered in one of the reactors and was leaking cyclohexane. The plant was subsequently shutdown for an investigation which revealed a serious problem with the reactor. A decision was taken to remove the reactor and install a bypass system to connect the reactors on either side so that the plant could continue production. On 1 June the bypass system ruptured resulting in the escape of a large quantity of cyclohexane. The cyclohexane formed a flammable mixture and subsequently ignited. At 16:53 hours there was a massive vapour cloud explosion. The plant was destroyed, 28 workers were killed and a further 36 suffered injuries. Reported offsite injuries numbered fiftythree and several nearby properties were damaged.

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In Seveso, Italy on 10 July, 1976 an industrial accident occurred in a small chemical manufacturing plant owned by Givaudan and Roche. During the production of an herbicide, fungicide, and chemical intermediate, an uncontrolled reaction occurred bursting the security disk of the tank and releasing a jet of chemical steam into the atmosphere. Several kilograms of a dioxin were released into the atmosphere and the chemical was spread throughout a large section of land between Milan and Lake Como. Somehow the mixture of chemicals which had been left in a boiler mid production cycle managed to spontaneously react producing enough heat and energy to eventually cause a runaway reaction. 3,000 pets and farm animals died and 70,000 animals were slaughtered later to prevent dioxin from entering the food chain. 193 people in the affected areas suffered from chloracne and other symptoms. The disaster lead to the creation of the Seveso Directive, which was issued by the European Community and imposed much harsher industrial regulations. To implement the EU Seveso Directive in the UK the Control of Major Accident Hazards Regulations 1999 (COMAH) were introduced. COMAH applies mainly to the chemical industry; some storage activities, explosives and nuclear sites, and industries where high quantities of dangerous substances are kept or used. It is useful to review the general requirements of COMAH as best practice requirements for controlling major accident hazards.

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Controlling Major Accident Hazards ‘Dangerous Substances’ include a number of named substances and substances falling into certain categories such as: 

Toxic;



Oxidising;



Explosive;



Flammable;

Scope of Responsibility Employer responsibilities are established based on threshold quantities of dangerous substances that are present on the site. They apply to establishments where dangerous substances are present in sufficient quantity to have the potential to result in a major accident hazard. The quantities varies from substance to substance ranging from 0.001 tonne for certain carcinogens to 50,000 tonnes of automotive petrol and other petroleum spirits. There are two thresholds, known as the top tier and the lower tier and these are determined by inventory.

General Responsibilities All site operators must take all necessary measures to prevent major accidents and to limit their consequences to people and the environment. Employers must communicate any necessary information to the public, emergency services and relevant authorities. In the event of incidents the employer must provide restoration and clean-up of the environmental impact. Prevention should be considered in a hierarchy based on the principles of reducing risk to a level which is as low as is reasonably practicable (ALARP). This is an expression which is used to define a standard or point at which the cost of additional risk reduction measures would be grossly disproportionate to the benefits achieved. Wherever possible, the ideal should always be to avoid a hazard altogether. Operators must take measures to prevent major accidents by undertaking a risk analysis to understand and predict: 

The circumstances that might lead to a major accident; and



The potential consequences of such an accident.

Examples of situations to consider include: 

Loss-of-containment of substance due to vessel or pipe work failures;



Explosions, for example, caused by mixing incompatible chemicals in reactors; and



Major fires.

Major Accident Prevention Policy (MAPP) All site operators are required to have a MAPP. The MAPP document should set out your policy on the prevention of major accidents: in other words a statement of general intent which includes the aims and the principles you plan to adopt. The MAPP document doesn’t need to

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contain a detailed description of your safety management system (the organisation and arrangements for implementing the policy to ensure the control of major accident risks). However, it should give the enforcement authorities sufficient detail to show you have systems in place to cover all the aspects listed later in the section. Your MAPP document must describe the management arrangements of the major accident hazards at a particular establishment and should be specific to that establishment. A MAPP document is similar in approach to a health and safety policy document, but with two important additions: 

It must deal specifically with major accident hazards.



It must include measures to protect the environment.

You can adapt your existing health, safety and environmental policy statement to include the MAPP information or you may prefer to produce a separate document. Your MAPP document should be signed by a senior person in your organisation. As your MAPP document supplements your health, safety and environmental policies, you should make it available to those who need to see these policies including employees, employee representatives and contractors. The amount of detail in your MAPP should be proportionate to the level of the hazards present - the greater the hazards the more detail you will have to provide. For most establishments, the MAPP document will be relatively short and simple. If operators already have much of the information such as training records, internal site inspection records, audit reports, operating procedures, risk assessments, etc; they can simply refer to it within the MAPP document. The most important aspects of a safety management system for controlling major accident hazards are summarised in the following sections. The headings from the publication HSG65 are shown in brackets to illustrate the links between MAPP documents and the management of health and safety.

Organisation and Personnel at all levels Involved in the management of the major hazards (Organising) This information will probably already be contained in the company’s safety policy, but you need to ensure it refers specifically to the key roles for the management of major hazards. Your MAPP document only needs to discuss those aspects which are relevant to a major hazard. It should outline your system for addressing these issues. This includes how you identify training needs, and the follow-up you carry out, i.e. your training policy and your system for ensuring effective communication with and involvement of employees, and where necessary subcontractors. The MAPP document does not need to include detailed records, but should refer to them.

Identification and evaluation of major hazards (Planning and Implementing) The MAPP document should describe your overall aims, approach and policy for hazard identification and risk assessment. You need to describe how the results are used, e.g. your policy on eliminating hazards. You should not include detailed reports or results in the MAPP.

Operational control - procedures and instructions for safe operation (Organising; Planning and implementing) Your MAPP document should record how you ensure you have adequate management arrangements, workplace precautions and control measures in place for safe operation. It

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should outline your system for developing, reviewing and revising procedures, and describe how you make sure the procedures are properly communicated. You do not need to include details of the procedures, although you may wish to mention where the details are located. For example, your MAPP document could say that you use a permit-towork system for certain tasks, or an inspection and maintenance system for ensuring the integrity of safety and environmental critical control systems, but it does not need to include details of how these systems work. Your MAPP document needs to state how you modify procedures (including management arrangements) and plant. It also has to show how you ensure that any new plant on site is designed, constructed, installed and maintained to relevant standards. It is important that your MAPP document shows you have a workable system for identifying, assessing, and authorising modifications.

Identification of foreseeable emergencies and the preparation, test and review of emergency procedures (Planning and implementing) This section overlaps with your policy for hazard identification and risk assessment described previously. Your MAPP document needs to detail your policy on identifying possible major accidents and to show that you have plans in place to respond. It should indicate the types of major accidents you have identified and considered. It is important that you identify how major accidents could occur and establish adequate emergency arrangements for dealing with them. Some documentation of these arrangements is normally required. You need to consider the possible involvement of people in neighbouring premises (both residential and commercial) and the emergency services. Your MAPP document should include your policy on reviewing and testing the emergency procedures.

Monitoring performance You need to have a system for assessing whether your site continues to meet the objectives in your MAPP document, and whether the standards you set are being maintained. Your MAPP document should describe how this assessment takes place, and how you would correct any deficiencies. This part of the document also needs to include your system for reporting and investigating accidents and near misses, and to explain how you make sure that the lessons learned are implemented.

Audit and Review You need to have a system for making sure your management systems and procedures continue to be correct, and that they are being followed. Your MAPP document needs to describe how you use audit and review to maintain the validity of both the MAPP document and your safety management system. When should I update it? In addition to the requirement on you to review your MAPP and safety management system after audit, you also need to review them if you make any modifications which could have significant repercussions in respect of the prevention of major accidents, including changes to: 

Your establishment.



The type or amount of dangerous substances used.



How you process and/or store them.

It is good practice to review your MAPP, and the safety management system for implementing it, after any accidents or near misses, as well as on a regular basis, although this is not

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specifically required by the Regulations. Regular reviews and updates will make sure your MAPP remains correct and relevant.

Notifications Employers are required to notify competent authorities regarding any proposed operations. Notification by all employers is essential to enable the competent authority to plan its assessment and inspection programmes and ensure that operators comply with their responsibilities. Operators of new establishments should send their notification in advance of the start of the operation (normally three to six months). Changes in the quantities of dangerous substances and processes, or closure of the establishment, must also be notified to the competent authority by existing operators.

The notification requirements Essentially, what is needed is information about the operator, site, processes and inventory, including:. 

The name and address of the operator



The address of the establishment concerned



The name or position of the person in charge of the establishment



Information sufficient to identify the dangerous substances or category of dangerous substances present



The quantity and physical form of the dangerous substances present (or likely to be present)



A (brief) description of the activity or proposed activity of the installation concerned



Details of the immediate environment liable to cause a major accident or to aggravate the consequences thereof.

Safety Report Operators of Top-tier establishments are required to produce a safety report to demonstrate that they have taken all measures necessary to prevent major accidents from occurring, and to limit the effects to human populations and the environment if they do. The safety report will also provide the Competent Authority with a detailed description of the establishment and the associated hazards. This will provide a comprehensive description of the risks and the control measures in place, and will help the Competent Authority in conducting inspections. For establishments that are due to start construction a safety report must be submitted before construction begins, allowing any necessary changes in the design process to be addressed before construction starts. Construction can only start once the Competent Authority’s conclusions on the pre-construction safety report have been received. The safety report should be reviewed periodically and updated as necessary to reflect changes at the establishment. Review and update of reports should be no later than five years after the last submission. A review must not only detail changes that have taken place, but must assess any significant new risks brought about by the changes, detailing the necessary control measures and mitigation of major accidents. Copies of changes must be notified to the competent authority.

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On-site Emergency Plan Operators of Top-tier establishments must prepare adequate emergency plans for dealing with on-site consequences of a possible major accident. This plan must incorporate details of actions to be taken regarding off-site mitigatory action. Development of the plan should be based on the findings and actions as detailed in the Safety Report. All possible major accidents must be considered, including those events of reasonably foreseeable low-probability that have a high consequence, such as catastrophic vessel rupture resulting in large scale explosion. The degree of planning should be proportional to the probability of the accident occurring.

Off-site Emergency Plan The Enforcement authority for the area where a Top-tier establishment exists must prepare an adequate emergency plan for dealing with areas off-site effected by a major accident. The Off-site Emergency Plan will detail the roles and responsibilities of external services such as the emergency services, local authorities and environmental agencies in the event of a major accident occurring that effects off-site areas. The plan will also detail arrangements of how external services will assist with the On-site response.

Review and Testing of Emergency Plan The first test and review of both the On-site and Off-site Emergency Plans must take place within 3 years of the completion of the first version of the relevant emergency plan. Thereafter reviews should happen at least every three years or more regularly if changes indicate a need for review. If any deficiencies or inadequacies are revealed during the review of plans then these must be addressed. Should any of these changes affect Off-site plans then the Authority must be informed. Similarly the Authority must inform the operators of any changes in Off-site plans that may affect On-site plans.

Implementing Emergency Plans The duty to implement the On-site and Off-site plans lies with the operator and the enforcement authority. Both of these bodies must ensure that the plan takes effect immediately on discovery of a major accident to ensure the situation is controlled as early as possible and doesn’t snowball into a series of disasters. There must be a clear and logical decision making process in place to be followed strictly in the event of a relevant accident occurring. Processes must be in place for contacting external services and these roles need to be communicated with the responsible persons. The plans must specify the names and positions of the persons responsible for initiating them. The On-site plan should also specify who is responsible for sounding the alarms in the event of a major accident.

Provision of Information to the Public Members of the local population who are likely to be affected in the event of a major accident must be given specific information about the establishment, the hazards and the safety measures in place. The Competent Authority will define an area around the establishment within which the operator must provide such information. This area is known as the Public Information Zone (PIZ). The operator must be proactive in disseminating this information to the public, not merely providing the information in the event of an emergency. All information provided must be easy to understand and not loaded with complicated technical jargon.

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Provision of Information to Other Establishments In some instances it may be possible for an accident at one site to trigger an accident at another establishment nearby, thereby starting a domino effect. This situation could be catastrophic and could result in the emergency services being stretched to the point where they are unable to assist effectively in both accidents. It is therefore the responsibility of the Competent Authority to identify all establishments in the area that may affect neighbouring establishments in the event of a major accident.

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Title

Page

Emergency Control

TYPES OF EMERGENCIES FOR WHICH PROCEDURES SHOULD BE DEVELOPED ................................................. 3 PREPARING AN EMERGENCY PLAN..................................................................................................................... 5 DEVELOPMENT AND IMPLEMENTATION OF EMERGENCY PLANS .............................................................................................. 5 FIRST AID / MEDICAL TREATMENT .............................................................................................................................. 7 ACTIONS TO BE TAKEN DURING AND AFTER AN EMERGENCY ......................................................................... 10 IMMEDIATE ACTION .............................................................................................................................................. 10 POST-EMERGENCY ACTION...................................................................................................................................... 11 ASSESSING THE EFFECTIVENESS OF AN EMERGENCY PLAN ............................................................................ 12 REVIEW OF THE SITUATION TO IMPROVE ORGANISATIONAL HEALTH AND SAFETY ..................................................................... 12


BSC International Diploma | Unit 1 Element 1B: Applied Health and Safety Management Study Unit 1B4 | Emergency Control Learning Outcomes When you have worked through this Study Unit, you will be able to:

1.B.4.1 Identify the types of emergencies for which procedures should be drawn up 1.B.4.2 Prepare, maintain and communicate an emergency plan 1.B.4.3 Describe the actions to be taken during and after an emergency 1.B.4.4 Assess the effectiveness of an emergency plan 1.B.4.5 Advise employers on communication with external agencies in the event of an emergency

Unit 2:

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Types of Emergencies for Which Procedures Should Be Developed Emergency planning is a necessity requiring preparations to be made in the case of emergency conditions arising. Procedures should be drawn up for various types of emergency. These include:

Fire and Explosion These are both discussed in some detail in previous study chapters.

Flood and Other Natural Events Natural events such as high winds, storms or excessive rainfall can cause emergency conditions to arise at the workplace, e.g.: 

Winds may cause wind-blown dust.



High winds may cause structural damage.



Rain can cause flooding or prevent discharges flowing away easily.



Storm sewers may overflow.



An earthquake could have potentially disastrous consequences, both in terms of structural damage and later consequences, such as disease.

Not only may these adverse weather conditions cause risk to health and safety of people on the premises, but they may also endanger others in proximity to the site, and they may endanger the environment. For example, a quarry site where heavy rainfall causes contaminated water to breach on-site flood defences and flow into a local stream.

Equipment Failure Depending on the nature of the workplace and the plant present, there may be a need to consider the potential consequences of equipment failure and how such consequences would be dealt with. For example, if suspended access cradles are used for cleaning and maintenance work, procedures should be developed to manage a jam or seizure of the mechanism. Similarly, procedures should be in place in the eventuality that mobile elevated work platforms or order picking machines fail in the elevated position. Another example of a fail safe systems could be an instance involving a pump circulating fluid in a safety critical cooling system. There must be a system in place to ensure the fluid continues to flow and the cooling effect is maintained in the event of a power/equipment failure. This could be in the form of an emergency backup power supply, or an alternative cooling system, and should incorporate an alarm to alert the operator to the failure and the switch over to the alternative system.

Collapse of Building or Structure Though buildings and structures are not normally at risk of collapse, earthquake risk consideration may be necessary due to the nature of the structure itself, or the activities being carried out. For example: a building may become structurally at risk during the removal of structural walls during modification; an old derelict building may be structurally unsound

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because of its derelict state and may become even more unsound during the demolition process. A risk of collapse also exists after or during a fire.

Escape of Hazardous Substances. These could be flammable or may pose a biological or ecological hazard. Spillages can be caused by a variety of circumstances, e.g.: 

Road traffic accidents.



Failure of pipes, hoses or other equipment.

Once again, an analysis of the risks should be carried out. A source, pathway, target analysis should identify the pathways and targets. Appropriate emergency procedures and equipment should then be put in place to reduce the risk to a condition that is as low as practicable. The amount (and cost) of risk reduction measures will depend on the potential damage that could be done if the substances escaped, and the sensitivity of the receptor. Emergency plans can vary from complex off and on site emergency plans involving the local authority and emergency services, evacuation procedures and closure of roads and railways, to a small number of local procedures and spillage kits, to cover the spillage of a low risk chemical in a low risk situation. Large and complex sites will have an emergency officer, with a dedicated control room, meteorological information, drain plans, road plans etc., and usually a media communication officer. It is always prudent to practise emergency procedures, and most companies will have invited the emergency services (particularly the Fire and Rescue Services) to the site to reconnoitre as part of the planning process. Having an inventory of the chemicals in use on the site, and information concerning services (electricity, gas, water, etc.) is essential.

Intrusion into the Premises In certain types of workplace, there will be the possibility of trespass, perhaps with criminal intent. Workplaces may be at risk from various types of intrusion from various groups or individuals with widely varying motivations. Many premises are simply at risk from burglary or theft, and can combat this risk with appropriate security measures. Other premises are at risk from other types of trespass, for example, the naval dockyard that was accessed by two peace protestors as a publicity stunt. Since the protestors managed to gain access to the outside of a nuclear submarine, there were some concerns over health and safety risks.

Serious Violence against Premises or People The issue of workplace violence is one that the safety practitioner must be aware of in all workplaces, but it will not normally require the establishment of an emergency plan. However, in certain circumstances, emergency planning may be necessary to deal with this contingency. For example, a large sporting venue will develop plans to manage ground violence within its grounds and will liaise with the emergency services and local stakeholders to manage ground violence near its premises. Also, any organisations that deal with the public, including smaller employers, may find their employees at increased risk in certain situations. Should a disaster or emergency occur, organisations that will take an active part in dealing with the situation, such as hospitals, local authorities or the police may find themselves under extra pressure from the public, and this may take the form of violence.

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Preparing an Emergency Plan The most common type of emergency plan seen in all business is the plan to deal with Fire situations and this will be the focus for the remainder of this section.

Development and Implementation of Emergency Plans An emergency plan is a formal, written document designed to assist management with the control of specific hazards or incidents, so that minimum disruption to normal work activities will occur and the good name of the company will not be damaged. When the range of major disruptive circumstances which could arise have been identified, individual emergency plans will then cover the following main points with regard to each of the identified hazards: 

Event - A description of the possible emergency situation



Location –Where the emergency situation is likely to arise



Potential for harm – an estimate of the likely consequences and nature of harm



Immediate actions to be taken- letting people know what to do and where to go



Establishing the emergency response team – who does what – who’s in charge?



Identifying equipment needed for rescue and recovery



Control of the event – taking charge



Assessment of the event and review of effectiveness of arrangements



Damage limitation action and recovery plan including communication plan

In order that such a plan operates smoothly and efficiently, it is important that responsibilities are set down and understood.

Developing the Emergency Response Team The emergency response is critically dependent on having trained and competent staff to implement it. Specific duties, responsibilities, authority and resources must be defined. Among the responsibilities that must be assigned are: 

Reporting the emergency.



Activating the emergency planning.



Assuming overall command.



Establishing communication.



Alerting staff.



Ordering evacuation.



Alerting external agencies.



Confirming evacuation complete.



Alerting the outside population of the possible risk.



Requesting external aid.



Co-ordinating activities of the sub groups of the emergency management team.

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Contacting relatives. 

Providing medical aid.



Isolating plant.



Sounding the all-clear.



Communicating with the media.

All these responsibilities are essential elements of the plan and therefore must be assigned to capable staff. The possibility of absence or shift working needs to be considered to ensure that deputies are available. A number of external services such as the following may well also be involved: 

Emergency services (Police, Fire and Rescue, Medical aid)



Local companies.



Environmental agencies.



Technical expertise.



Utility companies (Gas, water, electricity).



Local transport.

Someone within the company should be trained in the responsibility for dealing with the media, as this can have a profound effect on company image.

Training Every place of work should have an emergency plan which should include the action to be taken by staff in the event of an emergency, the evacuation procedure and arrangements for calling the emergency services. Notices of emergency action must be prominently displayed and include the method for raising the alarm, the location of the assembly point and, where necessary, action to be taken to assist disabled or sensory-impaired people. An example is shown in the next figure.

Typical Fire Notice

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In order that staff may become familiar with the escape routes, assembly points, use of the equipment and how to summon the fire brigade, practice drills should be carried out regularly and, in any case, not less than annually. In larger workplaces, it may not be necessary to train all employees in the operation of the fire equipment but everyone should know what hazards the fire extinguishers are provided to cover and the danger of using the wrong type of extinguisher in areas of special risk. Sufficient numbers of employees trained in the use of the fire extinguishers provided should always be present when the workplace is occupied. This is most important in areas where there are special risks. In workplaces employing large numbers of employees, it may be appropriate to nominate certain employees to carry out specific tasks in the event of fire. These tasks might include acting as floor marshals, ensuring that the floor is completely evacuated during a fire evacuation, and reporting that fact to a control point. Others may have the task of closing down processes during an evacuation or ensuring that security is maintained whilst the workplace is evacuated. The training should ensure that these tasks are carried out efficiently and safely. Staff involved in certain activities will need instruction in their specific duties in the event of a fire. These could include kitchen staff, engineering and maintenance staff, receptionists and telephonists. Supervisory staff and those with particular responsibilities in case of fire should be given additional instruction and training (e.g. heads of departments, supervisors, security staff, fire marshals). Fire training and instruction given should be recorded in a log book or other suitable record and should be available for inspection. In all premises one person should be responsible for organising fire instruction and training and, in larger premises, a person or persons should be nominated to co-ordinate the actions of the occupants in the event of a fire. Although fire is the most common example, there are other emergency situations that require training. Employees at high risk from violence, for example, traffic wardens, hospital staff, etc., should be trained in how to deal with aggression or violent attacks. In many cases, this will include diffusing the situation but also often covers ‘breakaway’ techniques.

First Aid / Medical Treatment People at work can suffer injury or sudden illness. It is important for employers to make arrangements to ensure that all employees receive immediate attention if they are injured or taken ill whilst at work. Employers must provide adequate and appropriate equipment, facilities and personnel to enable first-aid to be given to employees if they get inured or become ill at work. Employers are required to carry out a first-aid assessment to enable them to provide an adequate and appropriate amount of first-aid for their organisation. To complete the assessment employers must consider the following factors:

Workplace hazards and risks (hazardous substances, dangerous machinery, emergency potential etc.).



The size of the organisation and number of employees on site.



The premises (how many buildings are on the site, number of floors, spread out, location to medical emergency services etc.).

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

Shift working or lone working employees.



Employees with disabilities.



The organisation’s history of accidents.



Annual leave and absences of first-aid personnel.

First-Aid Personnel Once the assessment of first-aid needs has been carried out, the findings can be used to decide what first-aid personnel must be provided. Appointed Persons – An appointed person must be provided as a minimum first-aid provision. An appointed person will take charge when someone is injured or taken ill and will call an ambulance if required. They will also be responsible for the first-aid box and its contents making sure that the box has sufficient stocks and that these stocks are not damaged and do not exceed the best before date. An appointed person does not legally need to have any approved training, however, there are training courses covering what to do in an emergency and cardio-pulmonary resuscitation (CPR) that appointed persons can take. Appointed persons must only give first-aid for which they have been trained. Qualified First-Aiders – First-aiders are those that have undergone an approved training course in administering first-aid and hold a valid certificate. First-aiders may be selected depending on many personal factors such as their reliability, disposition, communication skills as well as their normal duties and ability to absorb new knowledge and learn new skills. Firstaiders can undertake those of an appointed person. In high risk industries other suggested medical staff may include nurses and occupational health therapists. Employers must remember that first-aid provision needs to be available at all times people are at work. Therefore there must be more than one appointed person and first-aider with the workplace to cover annual leave and absences. It is good practice for employers to provide first-aiders and appointed persons with a book in which to record incidents which required their attendance. This record book is in additional to an accident book, but the two may be combined.

First-aid equipment The results of the first-aid assessment will establish what first-aid equipment must be provided to suit the needs of the organisation. As a minimum an employer must provide a suitably stocked and identifiable first-aid box as well as an appointed person. The first-aid box must not contain tablets or medications. Stocks and ‘best before dates’ must be checked on a regular basis by the appointed person or first-aider. An assessment may show the need for additional materials. For example organisations where mains tap water is not readily available for eye irrigation, at least one litre of sterile water (or another suitable alternative) in a disposable container must be provided.

First-aid facilities The first-aid assessment will indicate the extent of the medical facilities that must be provided. Examples of medical facilities can include:Quiet areas - Normally used by smaller companies who may use a quiet area in the office or set aside a small room for minor medical attention in the event of an incident.

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First aid rooms - These will be easily identifiable rooms or departments specifically equipped for first aid treatment and which is normally occupied with trained first aid personnel. The room must be big enough to fit a couch with enough space at each side for people to work. It should have a sink with hot and cold running water with soap and paper towels as well as drinking water and disposable cups. The room should ideally have a telephone or other communication equipment and be located close to a point of access for transport to hospital. Treatment centres - This is where a block or section of a building will be geared towards first aid and medical treatment. It will normally be staffed with full-time first aiders and/or medically trained staff to offer treatment for minor and in some cases, serious injury. These can normally be found on large construction sites and industrial premises.

Informing Employees Employers must inform all employees of the arrangements that have been made in connection with the provision of first-aid, including the location of equipment, facilities and personnel. First-aid arrangements operate efficiently when they are known and understood everywhere in the workplace. Displaying first-aid notices is a simple and effective way of communicating this information. Notices must be designed and worded carefully to ensure that the information is put across effectively to employees. Those with language and reading difficulties must be informed by other suitable means such as translated notices and the use of Braille. Induction trainings will ensure new employees are made aware of the first-aid arrangements.

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Actions to be Taken During and After an Emergency Immediate Action The objective of the emergency plan is to prevent fatalities and injuries, reduce damage to buildings, stock and equipment, and to quickly resume normal operations. The immediate action necessary will depend on the nature of the emergency, but the objectives will always be the same. We can distinguish between technological and natural emergencies. Technological emergencies might include: 

Fire/explosions.



Building collapse/major structural failure.



Spillages or releases of flammable/toxic substances.



Releases of biological or radioactive agents.



Loss of essential power or water supplies.

Natural emergencies could involve: 

Floods.



Earthquakes.



Severe windstorms.



Extremes of temperature including snow and ice.

The consequence of these might require some or all of the following: 

Evacuation.



Deal with casualties.



Deal with damage to plant/infrastructure.



Deal with damaged equipment.



Salvage vital records/documents.



Address work disruption.

This can be broadly presented as a sequence of actions that should be tailored to the nature of the emergency: 

Sound the alert.



Declare emergency.



Evacuate the danger zone.



Close off relevant services as well as anything else that could exacerbate the situation’s need for external aid.



Initiate rescue operations.



Attend to casualties.



Limit damage.

However, the following factors will determine the exact nature of the procedures and action required:

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

The type of emergency.



The size of the organisation.



The location of the organisation and proximity of outside aid.



The physical layout of the premises and the activities/materials in use.

Principal External Agencies to be Contacted in an Emergency An essential element of the emergency response is contact with the key external agencies that will need to be involved. These include: 

Emergency services such as: fire departments, ambulance services, police and specialist mobile rescue squads that provide first line assistance in dealing with the immediate consequences.



Security control may be an internal arrangement provided by an external service.



In the UK local authority need to be notified of major disasters and reportable dangerous occurrences, and consequently will be involved in any investigations to establish causes and remedial action.



In the UK the environment agencies that will require notification of emergencies that have significant environmental impact.



The media, who will require press releases and other information on the circumstances and consequences of the emergency.



If not in the UK it is essential that local and national laws are followed in regards to the notification of emergencies.

Post-Emergency Action Post-emergency action involves minimising the consequences of the emergency. It assumes that casualties have received suitable treatment and have been evacuated from site, and that buildings and equipment have been rendered in a safe condition. The key priorities then become: 

To provide information to relatives and the public on the facts regarding the consequences of the emergency and the circumstances, as accurately as known at that time.



To promote self-help and recovery to restore normality as soon as possible.



To evaluate the incident, establish all the relevant causes, and identify the lessons that need to be learned and the remedial action required, either to prevent a reoccurrence or to minimise future consequences.

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Assessing the Effectiveness of an Emergency Plan Having devised and implemented the emergency plan, it is essential to monitor its effectiveness. This will involve organising and carrying out drills and exercises to check that the plan operates in the way intended. At a simple level, regular education and training seminars can be used to check retention by staff of emergency plans, and to identify needs and develop preparedness skills. By seeking feedback at such sessions, it is further possible to assess the extent to which staff understand their role and, consequently, how effective they will be in delivering the plan. Tabletop exercises can be carried out with members of the emergency management team to assess their response to a likely scenario. The team might meet in a conference room setting and discuss their individual responsibilities, and how each member or sub-group would react to the given scenario. This type of exercise is useful in identifying areas of incompatibility in the plan where different sub-groups may have different immediate aims and objectives that may conflict and hinder progress. Drills allow the emergency management team and response team to actually perform their designated emergency functions. This type of activity is more costly and time consuming, and involves more personnel, but is more thorough than the tabletop exercise. It gives the opportunity to execute the plan in reality, and is invaluable in identifying weaknesses. An essential element of the plan is likely to be evacuation to designated areas or shelters. A common example is the fire drill. This part of the plan can be tested by having all personnel walk the actual evacuation route to the designated area, where the procedure for accounting for all personnel can also be checked. Full ‘mock-up’ exercises can be carried out to create a more realistic drill. These exercises should involve the emergency services and other parties – such as members of the public – as necessary, and must mirror the real scenario as closely as is possible. For example, a crash scene that is recreated with ‘injured’ passengers, and the involvement of the local emergency services, to test the response of in-house first-aiders and response crews. These exercises will obviously be very expensive and time-consuming to run, but can give invaluable insight into the in-house response effectiveness. Video footage of drills can be useful in assessing procedures as it gives employees and trainers alike the opportunity to look back over what happened and what actions were taken, without relying on memory. The ultimate test of any emergency plan is whether it actually works in reality. Consequently, should the worst case scenario occur and the emergency plan be implemented for real, it is essential that a full and in-depth review of all stages of the emergency, and the response to it, is carried out with the involvement of all parties.

Review of the Situation to Improve Organisational Health and Safety Any health and safety initiative needs to be monitored and reviewed regularly to ensure its effectiveness, and the emergency plan is no exception. We have already considered how we might assess the effectiveness of the emergency plan through exercises and drills. The plan should be revised if shortcomings are identified from these initiatives and, in any case, at least annually. Changes in plant infrastructure, materials used or key personnel are also reasons to review the plan.

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Title

Page

Work Equipment

THE MAIN HAZARDS ASSOCIATED WITH WORK EQUIPMENT ............................................................................ 3 MECHANICAL HAZARDS ............................................................................................................................................ 3 NON-MECHANICAL HAZARDS ..................................................................................................................................... 7 ASSESSING RISKS FROM MACHINERY AND WORK EQUIPMENT ....................................................................... 9 ASSESSMENT FACTORS ............................................................................................................................................ 9 CONTROLLING MACHINERY HAZARDS ............................................................................................................. 11 ELIMINATION OF HAZARDS BY DESIGN ....................................................................................................................... 11 SELECTION OF EQUIPMENT ..................................................................................................................................... 11 CHOICE OF SAFEGUARDING METHODS ........................................................................................................................ 11 PROTECTING AGAINST MECHANICAL HAZARDS .............................................................................................................. 13 PROCEDURAL CONTROLS – SAFE SYSTEMS OF WORK AND SIGNAGE ..................................................................................... 27 MAINTENANCE, INSPECTION AND TESTING ................................................................................................................... 28 PRE-USE CHECKS ................................................................................................................................................. 28 INSTRUCTION, INFORMATION AND TRAINING ................................................................................................................ 28 SUITABLE CONTROL OF WORKING ENVIRONMENT .......................................................................................................... 29 SAFE POSITIONING ............................................................................................................................................... 29


BSC International Diploma | Unit 1 Element 1B: Applied Health and Safety Management Study Unit 1B5 | Work Equipment Learning Outcomes When you have worked through this Study Unit, you will be able to:

1.B.5.1 Describe the main hazards associated with machinery and work equipment and explain how they may cause harm 1.B.5.2 Determine, implement, evaluate and maintain measures for controlling risks from work equipment

Unit 3:

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The Main Hazards Associated with Work Equipment The term “work equipment” has a very broad meaning and can include things like machinery, hand tools, power tools, access equipment, vehicles etc. In fact it could include virtually everything that an employee uses to do their work. There are many hazards related to the use of work equipment and these can be conveniently discussed as “mechanical” and “non-mechanical” hazards.

Mechanical Hazards The following are significant hazards presented by machinery: 

Crushing.



Shearing.



Cutting (or severing).



Entanglement.



Drawing in (or trapping).



Impact.



Stabbing and punctures.



Friction and abrasion.



High-pressure fluid injection.



Ejection of particles.

The hazards are illustrated below: 

Crushing happens when the body or a part of the body is caught between two moving parts of the machine or between moving and static objects such that they meet together.

Crushing

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

Shearing is where two parts of the machine are moving together to create a situation where one moves over the top of the other. This could result in the amputation of fingers or other limbs.

Shearing 

Cutting or severing is where a sharp-edged part of the machinery comes in contact with the person. As implied, it is a similar effect to what happens when someone cuts them self with a knife.

Cutting or Severing

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

Entanglement is associated with a single rotating part of a machine. Usually an item of clothing gets caught on the rotating part and the person is drawn rapidly to the machine.

Loose cuff

Projection

Entanglement 

Drawing in or trapping is where the body is caught between two moving parts and drawn into the machine. In-running nips occur at a point where a rotating part and a stationary part, or two counter-rotating parts meet, i.e. belt/wheel, chair/sprocket, etc.

Counter-Rotating (Gearwheels, Mangles) 

Impact is where a powered part of the machine hits the person.

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

Stabbing or puncture is caused by some sharp part of the machine or process penetrating the person. The wound is normally small on the surface but deep into the body.

Stabbing or Puncture 

Injury due to ejection is similar to that caused by stabbing or puncture, as described previously. Examples include injury due ejected material such as flying swarf or broken tooling.

Ejection 

Friction or abrasion is caused by coming into contact with a fast moving surface. The effect is a burn due to the generation of heat through the friction generated between the machine and the part of the body in contact. If the rotating or moving part has a rough texture, the effect will be to create an abrasion abrasion problem, similar to rubbing the hand hard against glass paper.

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

High-pressure fluid injection hazard is associated with the use of hydraulic systems. The pressure to which the fluid is subjected in the system can be quite high. Following a sudden release, for example, by a pipe or joint bursting, the fluid jet may have sufficient pressure to penetrate the skin and tissues of any person in the line of the spray. The problem is that it injects hydraulic fluid deep into the body where the circulatory system can distribute it widely.

Non-Mechanical Hazards Other types of hazards that result from exposure to or operation of work equipment include: 

Noise.



Vibration.



Electricity (electrical hazards).



Temperature (thermal hazards).



Radiation.



Hazardous substances.



Ergonomic issues.



Manual handling.



Combinations of factors.

Noise Noise is a hazard not only to the operator but also to those around. Its effects can lead to temporary or permanent hearing loss and tinnitus, and can impair working efficiency. It also causes communication problems by interfering with speech or audio warning signals. Vibration Vibration affects the body and, in extreme cases, can produce vascular disorders. It can also be responsible for nerve damage. Its effect may be localised, as from holding hand tools, or full body, such as from sitting in a poorly-designed driving position on vibrating machinery. Electricity Contact with electrical current can result in electric shock or electrical burns to the person but it is also an ignition source and therefore it can also be responsible for fires and explosions in the workplace. High/Low Temperature Thermal hazards arise from the extremes of either heat or cold. There are two ways they can affect the person: 

As localised effects, for example, burns from a cutting torch or hot surface.



In general overall health, due to the extreme environment, for example, in a furnace room or cold store.

Radiation The various forms of radiation, e.g. heat, ultraviolet, infra-red, etc., can create serious health hazards. An example of this could be the use of beta radiation to measure the thickness of paper manufactured on a production line.

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Hazardous Substances Materials used by the machine may give rise to hazards. This may be from contact with the substance(s), by fire or explosion, or by there being a biological hazard, for example, yeasts used in brewing. Materials created by a particular process may also pose a risk, for example, silica dust from breaking out concrete. Ergonomic The use of machinery can lead to physiological problems such as backache or upper limb disorders as well as psychological problems, such as stress. Ergonomic problems arise from a mis-fit between the person performing the task and the equipment they are using. Common risk factors are posture, pace of work, repetitions, controls and display systems and force. Manual Handling People pick up and move objects all the time at work, and any of these actions may present a hazard. The risk is that the action will cause an injury of some kind to the person undertaking the operation or, by causing the object to fall or move, there is a risk that someone else may be injured. The risk may be exacerbated by poor ergonomic design. Combinations of Factors It is unlikely that any one hazard mentioned above will be present in isolation. In practice, a machine will present a number of hazards in varying degrees of severity, for example, vibration is seldom present without noise. Each will have a combined effect which may cause those that are, in themselves, minor to have a much greater significance to the risk, that is, a synergistic effect.

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Assessing Risks from Machinery and Work Equipment Assessment Factors The use of risk assessment for the development of built-in safety features is a key principle for machinery safety. The utilisation of risk assessment provides for the systematic identification and control of the risks. It is an integral part of the strategy for risk control. The first stage is to set the parameters in which the use of the equipment will take place. This is required as it will affect later decisions, for example, the control measures for a risk will vary when equipment is used only infrequently when compared to equipment in continuous use. There are various factors to consider.

Persons at Risk Issues to consider concerning persons at risk include: 

Which people are at risk? Are they employees, such as operators/maintenance/cleaners? Contractors? Visitors? Passers-by? Are there any vulnerable groups at risk?



How many are at risk?



When are they at risk? All the time? During different shifts? At certain parts of an operation or process?

Likelihood of Injury This depends on: 

Technical factors such as the dangerous parts, the guards or other devices available and the controls/layout of equipment.



Procedural factors such as methods of work and maintenance requirements.



Behavioural factors such as information, instruction, training and the possibility of human error.

Severity of Possible Injury This depends on the nature of the dangerous parts and the types of injuries that are possible such as crushing, entanglement, laceration and/or injuries to limbs.

Need for Access Is there a need to go near the dangerous parts of the machinery? Would this happen during normal operation, for breakdown/maintenance/adjustment/servicing purposes, or for everyday cleaning?

Duration of Exposure Consider the amount of time that the exposure to a risk is likely to last. This will tie in closely with the activity going on.

Reliability of Safeguards Are the safeguards that are in place adequate to do the job? Are they well maintained and serviceable?

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Operating Procedures Are there procedures in place to ensure that all foreseeable risks have been addressed and safety measures introduced? Have warning notices and signs been put up to warn of the dangers of the machine?

Training Have all personnel who are required, as part of their job, to come into contact with the machine had suitable training?

A consideration of all of these factors will help the assessor to determine the extent of risk posed by the use of the machine (Including maintenance and cleaning operations), and will provide the assessor with valuable data which can then be used to help develop the most suitable control strategy.

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Controlling Machinery Hazards Elimination of Hazards by Design When taking action in the design stage to minimise the hazards from machinery in relation to access to dangerous parts of the machine there are a number of points to consider. The selection of the most appropriate guard is important. It is necessary to ensure that, during operation and maintenance, it provides the minimum interference with the function of the machine whilst still providing protection against the hazards. All guards have a number of key features: 

They cannot be used in all circumstances, hence the variety which exists.



They can fail to function.



They can be over-ridden, some more easily than others.



They require different levels of maintenance to remain effective.

These points must be understood by the designer and considered by the safety practitioner when undertaking their respective roles. The design of the workplace in which the machinery operates will also have an effect on the operation of such machinery and, if poorly designed, may increase the risk of hazards. Therefore, the design of the workplace is also very important.

Selection of Equipment When selecting work equipment, there are a number of points to consider: 

It must be fit for purpose. In other words, it must be able to do the job that you want it to do, for the conditions under which it will be used. Work equipment can be exposed to very rough treatment under poor environmental conditions.



It should conform to a recognised standard, for example, by being CE marked (For EU member states).



If the introduction of the equipment produces new risks, then these must be assessed and suitable control measures put in place. Typical examples might include: −

Ergonomic considerations.

−

Introduction of noise, electricity, flammable substances, etc.

−

Poor lighting, ventilation, etc.



It should be easily maintained by trained staff and have good reliability.



Controls should be positioned to ensure safe and ergonomic ease of use. Where necessary controls may need to be shrouded or incorporate double-handed controls to prevent accidental operation.

Choice of Safeguarding Methods The following should be considered as a suitable hierarchy of controls for safeguarding machinery: 

Where practicable, the provision of fixed guards enclosing every dangerous part or rotating stock-bar should be the first choice.

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

Where the former is not practicable, the next choice would be the provision of other guards or protective devices.



Where the second choice is not practicable, the provision of jigs, holders, push-sticks or similar protection appliances used in conjunction with the machinery would be applicable.



Finally, if none of the above is practicable, the provision of information, instruction, training and supervision will be the only alternative. Of course, this should also be provided in conjunction with any other measures chosen from higher up in the hierarchy.

It can be seen then that the preferred method of safeguarding is to totally enclose all dangerous parts of the machine. This is obviously not always possible so a balance has to be struck between what the machine is intended to do and the need for access to the dangerous part(s). Where no or very infrequent access is required, a fixed guard may well be the answer. If you have difficulty visualising a ‘fixed guard’ think of a domestic washing machine. The back panel, if removed, reveals pulleys and belts that drive the washing machine drum. Whilst it is in place, securely held by screws, access to those dangerous parts is denied. If, however, you are using the washing machine you do need access to the inside. To have a fixed guard across the door opening would be infuriating. So, to prevent the user coming into contact with the dangerous parts, another type of guard is used. If you have tried to open the door whilst the machine is going through its programme, the door will not open. Only when the machine has completed the cycle and the drum stopped, will the interlock guard open and allow access. We have talked about automatic washing machines, but let us now consider a typical bandsaw. A part of the blade will be necessarily unguarded to allow the work piece to be cut. In order to prevent body parts entering the danger zone resulting in cuts, we would use push sticks to feed the material on to the blade. The final part of the hierarchy requires the user to be trained and conversant with the machinery. By using this simple analogy, it can be seen that circumstances will dictate which safeguard, or combination of safeguards, will be most suitable for a given situation.

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Protecting Against Mechanical Hazards This section briefly outlines the various types of machinery guarding in use.

Fixed Enclosed Guards These are guards with no moving parts and are designed to prevent access by enclosing the hazard. There may be access points where materials can be inserted and withdrawn, and hatches for maintenance or inspection. Flooring or 700 grade chipboard sheeting. Inner face lined with 50 mm thickness of sound absorbent material

Roof to be constructed of similar material to the rest of the enclosure

Sliding safety window for access to controls

Hinged door for access

Sliding door to reduce aperture to be as small as practicable

Light switch for internal light Full length doors at rear for access and blade changing

Flexible fingers

Wide aperture when required to receive timber back for resawing

Access to gear levers

Feed roller assembly pedal

Hand adjuster for feed roller

Fixed Enclosed Guard

Fixed Distance Guards This type of guard has no moving parts and is designed to keep the person away from the hazard. The false table shown in the diagram serves as a fixed distance guard.

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Fixed guard

Transparent panel

False table

Fixed Distance Guard A fixed distance guard is a fixed guard that does not completely enclose a hazard, but which reduces access by virtue of its physical dimensions and its distance from the hazard. A distance guard that completely surrounds machinery is commonly called a perimeter-fence type guard. When it is necessary for work to be fed through the guard, openings should be sufficient only to allow the passage of material and should not create a trap between the material and the guard. If access to the dangerous parts cannot be prevented by the use of a fixed enclosing guard with a plain opening, then a tunnel of sufficient length should be provided.

Interlocking Guards When an operator is required to enter a hazardous area of machinery and where fixed guards are not a practical option, interlocking guards are the next best protective device. Interlocking guards are defined as a guarding system which, when the hazard area is open, prevents the machinery from operating. Implicit in this definition are three important points that control the design and operation of an interlocking guard: 

It must prevent movement of the dangerous parts of the machine when the hazard area is open.

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

It must not allow access to the hazardous area until the potential hazard has been made safe.



It must not allow the machinery to operate until the guarding system is fully operational.

Other factors of importance are: 

If the interlock system should fail, it should fail in such a way that the system remains safe.



The interlocking system should be difficult to defeat.

The operation of an interlock may be electrical, mechanical, hydraulic or pneumatic. The choice is often dependent on the power medium (e.g. hydraulic) in use to operate the machine. In more complex machines, a combination of interlocks may be in place. Electrical Interlocks The electrical interlock is used to ensure that the power to operate the machine is not available until the guard is in place. The position of the guard is detected by means of electrical limit switches. The two main types are described below. •

Normally-Open Limit Switch The design of the switch is such that the spring will keep the contacts open until pressure is applied to the roller follower. (See the first of the two diagrams that follow. The second diagram shows how a normally-open switch can be used in conjunction with an interlocking guarding system.) There are three serious defects in the use of normally-open limit switches: −

They are easy to defeat by simply holding down with the hand - or, more permanently, with some adhesive tape.

−

More seriously, if the spring should break, the switch would be left on, without any external pressure, and the guarding would fail to danger, leaving the operator vulnerable to an unexpected operation of the machine while the guard is open.

−

If the roller follower arm became bent or the bearing becomes still, the switch could become jammed in the on position, producing the same danger as above.

Normally-open limit switches are frequently used by manufacturers as a method of controlling interlocking guards. With the defects mentioned above, you can see they hardly satisfy basic safety criteria. You would be well advised to see they are designed out of new equipment before you take delivery. Mains supply

Bearing Spring Applied pressure

Roller follower and arm 06 - IDipOSH 1B5 v2 160514 Page 15 of 30 SWITCH “OFF” (OPEN) POSITION

©British Safety Council SWITCH “ON” POSITION


Normally-Open Electrical Limit Switch (Negative Mode)

Linear cam attached to guard

Mains supply Roller follower

(b) Guard open

(a) Guard closed

Switch with a Guarding System •

Normally-Closed Limit Switch In this switch, you can see that the spring is designed to close the contacts when there is no pressure on the roller follower, see diagram. The following diagram shows how the normally-closed switch can be used on an interlocking system.

Mains supply

Applied pressure

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SWITCH "ON" (CLOSED) POSITION

©British Safety Council SWITCH "OFF" POSITION


Normally-Closed Electrical Limit Switch (Positive Mode)

(a) Guard closed

(b) Guard open

Normally-Closed Electrical Limit Switch on an Interlocked System The design of the normally-closed switch is safer than that of the normally-open switch, in the sense that it is more difficult to defeat and, if the spring breaks, it will fail safe. There are, however, defects in the system: −

Wear, misalignment, or overrun of the linear cam on the guard will result in a fail-todanger condition.

−

If the guard is removed, the switch will become activated, creating another fail-todanger condition.

With its improved safety design, the normally-closed switch can be used to replace the normally-open type. Where limit switches have to be used, they can provide a safer system if each type is used in series. Magnetic Switches A common magnetic interlock uses magnetic forces to control and operate an electric switch. The following diagram illustrates this type of interlock.

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'T'-shaped actuating magnet E – Earth AB – common A – contacts normally open B – contacts normally closed

'T'-shaped recess 'T'-shaped magnet on rocker arm

Retaining magnet

Balance weight

Switch rocker arm

Electrical contacts

Magnetic Safety Switch The electrical contacts in the unit are held open by the effects on them of the retaining magnet and the balance weight. When the external T-shaped magnet system is brought into contact with the internal magnet, a repulsive magnetic force is generated, causing the magnet to move away. This action causes the contacts to close and activates electric power. This system is used on any machinery that has a lid or cover that is regularly being opened and closed. In general, the switch is robust and reliable, but there are two possible areas of weakness: 

Although the design of the magnetic fields produced by magnets is complex, they can, with difficulty, be defeated. The switch can therefore be opened with the magnet removed.



There is a risk that the electric contacts, under adverse conditions, could fuse together, so the switch would fail to danger. It is not possible to predict how likely the chances are of

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this failure occurring, but manufacturers of the units have recognised the possibility and their research has given them confidence to believe that such a fault could not occur.

Magnetic switch closed

Guard closed

Counter balance weight Magnetic switch open

Guard open View from back of machine

Safety Switch in Operation

Key Systems This type of interlock ensures that power to a machine is locked off if guards are open. Its operation is shown in the following diagram. A master key in the power-supply unit is turned to switch power off. This key may now be removed to operate the guard key access unit, which holds a number of keys necessary to open guards on the machine. When one or more guard keys are removed to unlock a guard, the master key is trapped in the access unit. Power remains locked off. When access to hazard areas is no longer required, guards are locked, and the keys are returned to the access unit. Not until all keys are securely in may the 06 - IDipOSH 1B5 v2 160514

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trapped master key be removed. It is then available to operate the power supply to the machine.

Power supply unit (power ON, master key IN)

(power OFF)

Guard key access unit Key A for area A

Key B for area B

Master key trapped

A

B

Hazard area guard on

Hazard area guard on

A

Guard open key A trapped

B

Guard open key B trapped

Interlock Operation

Time Delay Interlocks A time-delay interlock system incorporates some type of mechanical device that takes a long time to release after power has been switched off. They are fitted to machines where the system continues in motion after the power has been removed, e.g. centrifuges.

Automatic Guards Automatic guards may be defined as ‘guards that forcibly move persons from the hazard area (sweep away) before the machinery operates’. In theory, the person should not be able to enter the hazard area while the automatic guard is operating. As the guarding system uses motion as an essential part of its protective mechanism, doubts as to the acceptability of such a system must be raised. Apart from the concept of motion being the fundamental cause of machinery hazards, there are practical considerations, such as: 

The speed at which the guard has to operate to overtake the hazard may be dangerous.



Tall persons may fall or lean over the guard into the hazard area.

A typical arrangement for a power press is shown in the next diagram.

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(a)

Automatic Guard

Trip Devices

(b) Guard “in” position

(c) Guard “out” position

There are operations that make it impossible to fit either a fixed guard or interlock. In such circumstances, the best type of system to use is a trip device, defined as a guard that stops or reverses motion when a person enters the hazard area. Machinery which is normally in continuous motion has a trip device fitted so that protection is given either when a person has to enter the risk area temporarily, or if an entanglement occurs where a person is being drawn onto (or into) the moving part. The effectiveness of any trip device relies heavily upon the efficiency of the stopping device; it cannot be emphasised too much that maintenance of such devices is a top priority. When a trip guard is activated by an accident, it should not allow further operation of the machinery until it has been reset. Ideally, a test circuit should be incorporated, so the trip action circuit can be checked without activating the mechanism. Trip Bar for Radial or Pillar Drills The next diagram illustrates a trip bar guard that can be fitted to pillar drills. A micro-switch attached to the trip bar will, if slightly displaced, cut off AC supply and inject DC into the motor, so that it stops instantly.

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Trip Bar Guard A few important points to watch in the use of this type of system are: 

Maintenance of maximum sensitivity for the trip bar, i.e. the minimum of movement is required to activate the micro-switch.



Monitoring of the micro-switch for contact wear.



Ensuring that the trip guard is not being used as an operational brake for the drill.

Photo-Electric Guards Another form of trip device used for press brakes and hydraulic presses is the photo-electric guard. The guard operates by creating a light-curtain across the hazard area. If any of the beams are broken, the unit is brought to an almost instantaneous stop. It is claimed that, with the absence of moving parts (which will wear), the unit is very economical in terms of maintenance costs. The light-screen should incorporate a self-checking system between each operation of the machine, so that any defects will cause the equipment to fail safe. Safety Switch Mats or Trip Mats You may well be familiar with floor mats that cause a door to open as an approaching visitor steps on them. The concept of mat-pressure contact circuits has been applied in the development of safety mats, known as safety switch mats, or trip mats. The mats are positioned round a machine at an appropriate distance from the hazard. Pneumatic or lowvoltage electric contacts within the body of the mat are linked to the power circuit of the machine, in such a way that stepping on the mat shuts off the power. The same principle of using contact pressure is found in devices known as safety edges. Narrow strips are fitted to sliding doors or machine parts that might close to trap a person. Circuits from the pressure strips halt the closing movement and, if desired, reverse it to avoid the trap.

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Adjustable Guards It may be impracticable in some situations to prevent access to the dangerous parts because they are unavoidably exposed during use, for example, the cutters on milling machines and the cutters of some woodworking machines. In such cases, the use of an adjustable guard may be permissible in conjunction with other closely supervised conditions, such as a sound floor, good lighting and adequate training of the operator. An adjustable guard provides an opening to the machinery through which material can be fed, the whole guard or part of it being capable of adjustment in order that the opening can be varied in height and width to suit the dimension of the work in hand. It is essential in such cases that the adjustment is carefully carried out by a suitably trained person. Regular maintenance of the fixing arrangements is necessary to ensure that the adjustable element of the guard remains firmly in place when once positioned. The guard should be so designed that the adjustable parts cannot easily become detached and mislaid. Adjustable guards are guarding systems that require manual adjustment to give protection. They are used on woodworking machinery, milling machines, lathes, drills, and grinders. Many of the guards are designed so the work piece can be observed during the machine operation. Windows of perspex, polycarbonate or armoured plate glass allow the operator a clear view. Some systems are made with a telescopic fencing or a slotted movable casting, both systems allowing observation of the work piece. The following adjustable guarding systems are in common use:

Adjustable guard

H

Circular Saws Circular Saw with Adjustable Guard

The cover is adjusted so that the height H is large enough for the work piece to be cut by the saw.

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Vertical Drills or Woodworking Moulder The transparent cover that allows a clear view of the drill or cutter is adjusted and secured in position by the thumb screw T.

Thumb screw “T”

Movable guard

Drilling Machine Chuck Guard The use of adjustable guards is allowed in many situations by the inspecting authorities but critical thought should be given before they are used as a guarding system. Their main weakness lies in the fact that they are controlled by the machine operator, and not by the person or organisation responsible for controlling the safety of the workplace. As a consequence there are two potentially serious risks: 

They can easily be defeated.



They rely upon operators being 100% vigilant in providing for their own safety, a condition the guard should provide, not the operator.

Where adjustable guards are used, strict training and supervision of operators is of paramount importance.

Self-Adjusting Guards A self-adjusting guard is a fixed or movable guard which, either in whole or in part, adjusts itself to accommodate the passage of material, etc. This type of protection is designed to prevent access to the dangerous part(s) until actuated by the movement of the work piece, i.e. it is opened by the passage of the work piece at the beginning of the operation and returns to the safe position on completion of the operation. Consideration should be given to the use of feeding and take-off devices, jigs and fixtures when this type of guard is used. The next figure shows a typical arrangement. The guard rests on top of the work and closes fully when removed. Note that this kind of guarding can be difficult for the operator and is easy to defeat. However, it is sometimes the only practicable method.

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Enclosing hood which moves up and down with the saw

Visor front

Separately pivoted peripheral strips (self-adjusting guard)

Typical Arrangement of a Self-Adjusting Guard

Two-Hand Control Where guarding is impracticable, as in the next illustration, two-hand control offers a means of protecting the hands of the machine operator. It may also be used as a hold-to-run control. A two-hand control device requires both hands to operate the machinery controls, thus affording a measure of protection from danger to the machinery operator only. It should be designed in accordance with the following: 

The hand controls should be so placed, separated and protected, as to prevent spanning with one hand only, being operated with one hand and another part of the body, or being readily bridged.



It should not be possible to set the dangerous parts in motion unless the controls are operated within approximately 0.5 seconds of each other.



Movement of the dangerous parts should be arrested immediately; or, where appropriate, arrested and reversed if one or both controls are released while there is still danger from the movement of those parts.

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

The hand controls should be situated at such a distance from the danger point that, on releasing the controls, it is not possible for the operator to reach the danger point before the motion of the dangerous parts has been arrested.

Two-hand Control Device There are, unfortunately, difficulties with the use of two-handed controls: 

Experience has shown that most two-handed two handed systems will eventually be defeated by the determined operator.



During operation, the system protects the operator; third parties are always at risk.



Often, frequent maintenance is required, as most systems require a complex mechanism in order to make them effective.

The use of two-handed handed control systems as a method of guarding machinery must be considered as having very limited practical value.

Emergency Stop Devices These are emergency devices and should not be used routinely to stop machines. They must not be considered as alternatives to guarding the machinery. The UK’s British standard, BS 3641 requires for emergency stops to have a red mushroom mushroom-head push-in in button against a yellow llow background. Normally they should be of the lock-in lock in type and resetting the stop should not restart the machine!

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Emergency Stop Device Emergency stops should be located at each work station and be both prominently displayed and easy to reach.

Procedural Controls – Safe Systems of Work and Signage Safe Systems of Work Most of the comments so far in this study unit relate to the guarding of machinery in its working state (and to some examples of non-functioning state). However, machinery is not always working; tasks are required to set up and adjust the machine, for which the choice of guard becomes important. Similarly, cleaning and maintaining the machinery is important to ensure that it is fit to function when required and to prolong its operational life. Here we shall look at some of the aspects of protection of persons from machinery dangers when undertaking these tasks. The basic premise starts with having in place a safe system of work that manages the risks. It may not be possible to introduce the same level of protection as when the machine is working, but remember that time of exposure should be taken into account.

Signage: Markings and Warnings All controls for work equipment must be clearly visible and identifiable by appropriate marking. The markings and warnings required will depend on the hazard and risk generated by the equipment. This, in turn, will depend on the task being performed and the type of equipment being used. Examples are: 

Operating instructions.



Safe working load (SWL) marked on cranes, forklift trucks, lifting chains and tackle and ropes.



Maximum and minimum speeds for abrasive wheels, circular saws, band saws.



Maximum and minimum size of components or work pieces.



Hot, cold and abrasive surfaces.



Ejection hazards, such as fumes, swarf, sparks and dust, etc.

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Some markings may be specific, such as ‘RADIOACTIVE’, whilst others may be more general, such as ‘MIND YOUR HEAD’. Markings can comprise words, letters, shapes or pictograms. Specific visual or audible warning devices may be required to alert people to danger – for example, flashing lights on equipment, lights on control panels to signal that something is faulty or is still hazardous, reversing alarms on vehicles, etc. Visual warnings are limited in that they rely on people looking in that particular direction. Audible warnings will not be suitable in a noisy working environment, especially if employees are wearing ear defenders.

Maintenance, Inspection and Testing Setting, Cleaning and Maintaining Access to danger zones should be minimised by locating maintenance, lubrication and setting points outside the danger zones. This is to include access to such places, for example, by means of stairs and ladders with protection against falls as required. It should be possible to carry out adjustment, maintenance, repair, cleaning and servicing operations with the machinery at standstill. If this is not possible for technical reasons, then these activities must be able to be performed without risk.

Inspection There is also a requirement for planned preventive maintenance, based on regular inspection of work equipment, in cases where safety depends upon the installation conditions, or where it is exposed to conditions liable to cause deterioration to a dangerous state. Such inspections must be carried out in accordance with a specific written system designed to cover: 

Initial inspection where incorrect installation may give rise to a risk (prior to its first use).



Specific planned inspection of particular parts and general operation where deterioration or exceptional circumstances may give rise to risk.



Breakdown maintenance when a failure or malfunction has occurred.

Employers must keep records of such inspections and the remedial action taken, but no general requirement exists for maintenance log-books. Relocated equipment must be accompanied by some form of inspection log, and hired or borrowed equipment must not be used without evidence of the last inspection. The frequency of inspection of work equipment will depend on its use, operating conditions, variety of operations and the risk it may pose to health and safety from any malfunctions or failures. Certain pieces of equipment have statutory requirements, regarding frequency, e.g. cranes, ropes, pulleys, vehicle hoists, lifts, and portable electrical equipment.

Pre-Use Checks Although many items of equipment require periodic inspections, or in some cases statutory tests/inspections, all items of work equipment should be subject to a pre-use operator check. The level of detail involved in the pre-use check depends on the level of risk involved, and should be decided on through the risk assessment process. In higher risk instances, this check may be documented.

Instruction, Information and Training Operator error is a major cause of accidents – either as a result of by-passing guards to speed up work or simply by mistake. It is essential, then, that workers are fully aware of the risks associated with operating the particular machinery they work with, exactly how the protective

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devices work and how they are expected to work safely with them. This applies even where the hazard is protected by fixed guards, and operators need to be fully instructed in the operational use of adjustable guards. In addition, there may be residual risks that can only be eliminated by the operator keeping to set, safe procedures and working practices. Employers must, therefore, ensure that all users of work equipment have received specific training in its safe operation. The level of training required will reflect the complexity of the equipment and its inherent dangers. Some equipment will require a high degree of training, including the possession of recognised certificates – for example, for abrasive wheel mounters and setters. On the job instruction and training may be sufficient for many operations, such as the operation of machine controls (including emergency controls) and the changing of machine components or work pieces. Employers must inform employees of hazards arising in the workplace. With work equipment, this can be achieved by suitable markings. Tool-box talks or on the job training are other ways of disseminating information. These also provide a medium for instruction.

Suitable Control of Working Environment The technical aspects of machine safety are not the full story. It is necessary to incorporate other controls and measures to ensure that machinery is used safely and maintained in a safe condition. Apart from issues relating to the machine itself, we should also recognise the importance of a number of issues relating to the immediate environment of the machine and the way in which it is used. Specific responsibilities are placed on employers in relation to the following issues:

Stability Any item of work equipment, or any part of work equipment, that should be used in a fixed position, must be secured to prevent movement. This may be by bolts, clamps, ties, etc. or, in the case of mobile equipment such as cranes, by the use of stabilisers and outriggers. Account must be taken of the operating conditions when deciding on the need for a fastening and the type to be used. For example, equipment may be used outside, and may be affected by different weather conditions.

Lighting Suitable and sufficient lighting, which takes account of the operations to be carried out, must be provided at any place where a person uses work equipment. Additional lighting, over and above general lighting levels, may be needed in respect of particular areas of the machinery, such as where access to dangerous parts is required. It may also be needed for particular operations, such as maintenance, or where dangerous operations, for example, excavation, demolition, or working in the dark may be carried out.

Safe Positioning Clear and Unobstructed Workspace The space within which workers are required to operate a machine should be such as to allow complete freedom of movement as necessary to perform all the necessary operations in a safe manner. Congestion can arise for many reasons, including: size of rooms or workstation, number of people sharing the space, storage of materials, waste, passing traffic, furniture, amount of

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machinery and equipment, etc. Employers should take into consideration all the factors likely to give rise to restrictions on space. In particular, the following points should be considered: 

Space should be provided around each machine to allow clear separation from passing traffic, and for the storage of tools and work-in-progress.



The operator of any control is able to ensure from the control position that no person is in a place where he or she would be exposed to any risk to his or her health or safety.



Systems of work are effective to ensure that, when work equipment is about to start, no person is in a place where he or she would be exposed to a risk to his health or safety as a result of the work equipment starting. Where this is not reasonably practicable, physical barriers or floor markings may be needed to ensure an unobstructed workplace.

If Mobile Work Equipment is being used, attention should also be paid to other possible obstructions, such as overhead and underground hazards. These could include overhead power lines and sewers, which would need to be taken into account when positioning Mobile Work Equipment.

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Title

Page

Occupational Transport and Driving

MAIN HAZARDS ASSOCIATED WITH WORKPLACE TRANSPORT ......................................................................... 3 COLLISION ........................................................................................................................................................... 3 FALLS FROM VEHICLES ............................................................................................................................................. 4 FALLING LOADS ..................................................................................................................................................... 4 VEHICLES OVERTURNING .......................................................................................................................................... 4 STRIKING SERVICES OR OBSTRUCTIONS ........................................................................................................................ 6 EXPLOSION OF BATTERIES AND TYRES ......................................................................................................................... 6 HAZARDS SPECIFIC TO FORKLIFT TRUCKS ...................................................................................................................... 6 TYPICAL CAUSES OF FAILURE ..................................................................................................................................... 7 MEASURES FOR CONTROLLING RISK FROM WORKPLACE TRANSPORT ............................................................. 9 RISK ASSESSMENT.................................................................................................................................................. 9 SAFE OPERATION ................................................................................................................................................... 9 SEGREGATION OF VEHICLES AND PEDESTRIANS ............................................................................................................... 9 PROVISION OF SAFE TRAFFIC ROUTES ........................................................................................................................ 10 BANKSMEN/ VEHICLE MARSHALS............................................................................................................................... 12 DRIVER TRAINING ................................................................................................................................................ 12 SIGNAGE ........................................................................................................................................................... 13 SAFE USE OF MOBILE EQUIPMENT ............................................................................................................................. 13 OCCUPATIONAL DRIVING ................................................................................................................................ 16 OCCUPATIONAL DRIVING HAZARDS ............................................................................................................................ 16 REDUCING THE RISKS FROM OCCUPATIONAL DRIVING...................................................................................................... 17


BSC International Diploma | Unit 1 Element 1B: Applied Health and Safety Management Study Unit 1B6 | Occupational Transport and Driving Learning Outcomes When you have worked through this Study Unit, you will be able to:

1.B.6.1 Describe the main hazards associated with occupational transport and driving and explain how they may cause harm 1.B.6.2 Determine, implement, evaluate and maintain measures for controlling risks from occupational transport and driving

Unit 4:

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Main Hazards Associated With Workplace Transport Workplace transport covers a wide range of vehicles from those which are driven by an on board driver to those which are towed to very sophisticated transport systems within an automated environment. Some common types are as follows; Typical Machines Self-propelled

Towed

Mounted (attached but removable)

Forklift trucks (rough terrain)

Trailers

Road brush

Dumper trucks

Compressors

Forklift attachment

Excavators

Water bowers

Back-actor (digger)

Tractors

Land graders

Loader (front mounted)

Road surfacing equipment

Post auger Cultivator

Typical hazards and causes of failure include:

Collision Any situation that involves crossing a vehicle traffic route is a hazard, particularly where visibility is restricted and it is not possible to see the approach of vehicles clearly. Emerging from doors can present a problem where the exit leads straight on to a vehicle path, or if vehicles are obscured by building debris, stacks of scaffolding, etc. Other hazardous situations include: 

Working in proximity to moving vehicles, such as in loading bays or carrying out road repairs.



Where vehicles cross or move around areas that are normally reserved for pedestrians.



Where reversing or refuelling is necessary.

Assuming driver competence, collisions with other vehicles, pedestrians or fixed objects are generally caused by adverse local conditions: 

Poor weather – ice or rain causing skidding or longer braking distances, sunlight blinding vision, rain or fog restricting visibility.



Poor lighting – decreasing visibility or obscuring parts of the traffic route, including obstructions.



Poor sight lines – causing blind spots and concealed junctions.



Poor ground surface – uneven muddy or slippery surfaces or excessive slopes.



Congestion – there simply being too many vehicles in one area.

The hazardous situation created by local conditions can be worsened by human failure and error, such as:

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

Ignoring weather conditions.



Speeding.



Lack of concentration.

Vehicles or Loads Striking People Collisions may be the result of: 

Striking against stationary objects (except impacts due to a previous fall).



Striking against moving objects.



Being struck by moving objects (including flying fragments and particles) excluding falling objects.

Falls from Vehicles Falls from elevated areas of vehicles during loading, unloading, sheeting and checking operations often occur when people have to gain access to the tops of vehicles. The risk of injury may be reduced by the provision of safe means of access to and from the vehicle, instructions to staff and the use of mechanical aids where appropriate. For example, to prevent people sheeting a lorry from the vehicle itself, a sheeting shed can be used, where the sheets are rolled onto a roller that is horizontally raised on a gantry above the lorry. The sheet is secured at the leading end of the lorry, which is driven forward, pulling the sheet from the roller and spreading it over the load. The tail end of the sheet is then secured by hand at ground level. Many other vehicles have similar systems already incorporated, that can be pulled from the ground, including lorries with on board sheeting systems. Some vehicles, such as car transporters have guardrails that are positioned at low level, and that prevent falls when the decks are raised.

Falling Loads Many accidents are caused by the loads carried by the vehicle becoming unstable and falling off, causing the vehicle to overturn or the driver to lose control. Loads do not do this by themselves – it happens because of some deficiency in the loading (or unloading) procedure such as: 

Overloading.



Uneven distribution.



Unsecured loads.



Slippery surfaces on the vehicle or load itself.

Vehicles Overturning There are two main ways in which a vehicle may turn over: 

Lateral instability: a vehicle turning onto its side, as when a high-sided lorry is blown over in high wind, or when a loaded forklift tips over whilst driving across a slope.



Longitudinal instability: a vehicle turning onto its front or back, as when a tractor's front wheels lift due to the weight applied by an attached trailer, or when a forklift truck is moving up or down a slope.

Overturning is caused by the centre of gravity of the vehicle moving outside of its wheelbase as shown in the following diagrams of loaded forklifts.

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With forklifts, the higher a load is carried vertically going down a slope, the more unstable the vehicle is as the load centre is increased. It is, therefore, better for forklifts to reverse down slopes with the load as low as possible. See the diagram later in this section. Such instability is a major problem in the safe use of high vehicles, particularly those with lifting mechanisms. The risk is increased by: 

The speed of travel.



The steepness of the slope.



The height the load is raised to, as well as the stability of the load.



Increased or incorrect tyre pressure.



Any external longitudinal pressure, such as wind or colliding objects.



Presence, and size of, any bumps or holes in the surface.

Note that a similar effect to that of a slope may be caused by uneven ground. Where a vehicle goes over a pothole, for example, the front wheels will dip giving the effect of a slope. Forklifts are the most critical of vehicles here, as they have small wheels that will exaggerate the effect and no suspension to keep the body steady. (b) LOAD

CG CG

(a)

CG P LOAD

CG W

L y

P

P LEVEL GROUND

x

Loaded Forklifts In the diagrams illustrating ‘Loaded Forklifts’, shown above, the left-hand diagram shows a forklift truck carrying a load high on the forks, travelling down a slope forwards. As discussed earlier, this is a hazardous practice, and it would be better to reverse down the slope with the forks lowered. The right-hand diagram shows the effect of a slope on the centre of gravity of a load with the forks lowered (a) and then raised (b). In diagram (a), the centre of gravity is within the wheelbase but in diagram (b), with the forks raised, the centre of gravity is outside the wheelbase and a risk of overturning exists. A key to the diagrams follows: y

The distance of the centre of gravity from the pivot point of the forklift truck body.

CG

Centre of gravity.

x

The distance of the centre of gravity from the pivot point of the load.

P

Pivot point.

W

Gravitational force acting on the truck (weight).

L

Gravitational force acting on the load (weight).

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Striking Services or Obstructions An obvious hazard associated with vehicle movement is collision with fixed structures, equipment, services and overheads. This can give rise to significant damage to the vehicle involved, damage to the structure and equipment that has been struck, and may generate serious safety risks because of the nature of the equipment involved. For example, an inappropriately sited mobile crane might contact overhead electrical cables, with resultant arcing, electric shock, and fire and explosion hazards, not to mention the disruption caused by the power failure. Alternatively, a poorly driven forklift truck may strike a section of racking support, buckling the support and weakening the racking structure to such a degree that the racking needs to be removed from use and subsequently repaired.

Explosion of Batteries and Tyres For electrically operated trucks as well as other vehicles, there is the danger of production of hydrogen gas whilst charging the batteries, as well as the manual handling implications of changing them. For gas (LPG) operated lift trucks, there is a fire and explosion risk, particularly during the changing of cylinders. Hazards arise from poor maintenance of brakes, steering, tyres, lights, etc., and emission of substances whilst being used, i.e. exhaust gases. Batteries of battery-operated lift trucks must be checked to ensure that they are adequately charged and leak free, that the charger is switched off, the charge lead disconnected and properly stored, and the battery retention device is in place. Another explosion risk associated with vehicles is the possibility of tyre explosion. These can be very violent if the vehicle involved is an item of heavy plant, where the tyre pressures will be high as a consequence of vehicle weight. For example, workers have been killed when attempting to free up seized wheel nuts with oxyacetylene equipment – excessive heating leads to a weakening of the tyre structure and catastrophic release of tyre pressure as a result. There is also a risk of explosion of tyres when splitting or inflating a split rim tyre, if the rim is incorrectly fitted.

Hazards Specific to Forklift Trucks The specific hazards related to forklift trucks were discussed in Study Unit 1B3, as well as general machinery and work equipment hazards. It would be worth revising these issues at this point. In summary, the main hazards associated with forklift trucks include: 

The risk of overbalancing, particularly as a result of the small wheels and the effects of heavy loads.



Hazards to do with batteries, such as manual handling risks when changing them and the production of hydrogen gas.



For LPG operated trucks, there is a risk of fire and explosion.



Hazards arising from poor maintenance of brakes, steering, tyres, lights, etc., and emission of substances whilst being used, i.e. exhaust gases, including diesel fumes in confined spaces.



Operator-related hazards, such as driving too fast, cornering at speed and incautious driving.



Impact with people as well as objects and structures while moving around.



Driving over unsuitable ground can increase the risk of loads falling.

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

Exhaust fumes from diesel-powered trucks, particularly in poorly ventilated areas.

In order to lessen the dangers associated with these hazards, special rules for forklift trucks should be applied. These include: 

The forks should be lowered whenever the vehicle is parked.



Violent braking of a loaded truck should be avoided as sharp movements could cause the load to fall or the truck to tip.



Whenever possible when driving, the forks should be lowered to within 150 mm of the ground and the mast tilted back. (Driving with the load elevated increases the risk of overturning.)



When a high load restricts vision, the truck should be driven in reverse, except when driving up a gradient.



To minimise the risk of overturning, when a loaded truck is travelling up or down a gradient, the forks should face uphill. When unloaded and travelling down gradients, the forks should face downhill.

Typical Causes of Failure Failure to Follow Procedures To ensure the safety of workplace transport, an essential component is the safe systems of work derived from risk assessment. These are set out in the site rules for vehicle operations. The following issues should be considered: loading operations, control of vehicle keys, rules for reversing, designated routes to segregate vehicles from pedestrians, and use of warning devices. Obviously, these procedures need to be implemented and adhered to, and any contravention is likely to produce a hazardous situation.

Operator Error In the UK alone approximately 20,000 reportable injuries involving moving vehicles at work sites occur each year, a third of which involve lift trucks. Many of these accidents, some of which are fatal, are caused by operator error. A particular problem is the use of lift trucks by untrained or unauthorised personnel.

Unsafe Loading or Transportation Many accidents occur during loading and unloading, and these may be substantially reduced by well-designed areas and safe systems of work for the procedure itself. Adequate space should be provided to allow access to all parts of the vehicle necessary for loading or unloading, and for the stacking and temporary storage of goods. The time that these are left before loading or removal (in the case of unloaded goods) should be minimised. Empty pallets and other material should not be allowed to accumulate in an unplanned way. There should always be sufficient clearance overhead, and particular care may need to be taken when vehicle bodies are raised. Loading procedures should ensure that: 

Vehicles are not loaded beyond rated capacities or the legal limits of gross weight.



The floor of the vehicle is checked for soundness before loading.



Loads are evenly distributed, and secured or arranged so that they do not move in transit.



Tail and side boards are closed.

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

Overhangs are kept to a minimum and suitably marked.

The following precautions should be taken when unloading: 

The load should be checked for stability before ropes, chains, straps or tarpaulins are removed.



The load should remain stable and evenly distributed as far as practicable during unloading.

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Measures for Controlling Risk from Workplace Transport Risk Assessment The need for a risk assessment has been mentioned throughout this Study Unit. The use of risk assessment for the development of built-in safety features is a key principle for many areas of the workplace, including the use of workplace transport. The utilisation of risk assessment provides for the systematic identification and control of the risks. It is an integral part of the strategy for risk control, as it helps us to decide how best to control the risk. The first stage is to set the parameters in which the use of the transport will take place. This is required as it will affect later decisions. There are various factors to consider, including: the vehicle, the driver, the route, the workplace, the systems of work, and pedestrians, including visitors and contractors on site.

Safe Operation Although more specific measures for controlling risks are discussed below, the following general issues should also be considered: 

Operator training is essential and strict rules about driving should be observed – particularly in respect of speed and direction of travel depending on the load, whether the forks are raised and whether travelling up or down an incline.



Particular care must be taken in the vicinity of pedestrians, both during movement and when lifting. The load should not be picked up if someone is standing close to it and people should not work or stand beneath a raised load. People should never stand on the forks or use them as a working platform, except where specially designed for such work.



Before lifting, the weight of the load must be assessed to ensure that the truck is capable of lifting it. The forks must be suitably adjusted for the load and placed in the correct position, and any attachments to cope with the special characteristics of the load should be fitted and checked. Loads that are unsuitable for the particular truck and its attachments should not be picked up, nor should loads or pallets that are damaged.



When lifting or lowering loads, the handbrake should be on and the mast should not be tilted forwards.



When two trucks are operating in tandem to lift or manoeuvre heavy or awkward loads, operations should be supervised by a competent person using recognised signals to guide both drivers.



As with all vehicles, forklift trucks must be used and maintained properly in accordance with the manufacturer’s specifications in respect of maximum lift height and capacity, and routine inspection, maintenance and servicing.

Segregation of Vehicles and Pedestrians Wherever possible, pedestrians should be physically segregated from vehicle traffic routes. Measures to ensure this include:

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

Barriers to separate pedestrians from vehicle traffic routes or, where this is impractical, the use of clear surface markings to delineate the separate routes. These are particularly required outside exits from buildings where there is a risk of pedestrians walking directly onto a road, as well as on walkways around construction sites. Surface markings may be unsuitable, for example, where the risk is great, such as on a narrow, slippery surface. In such a case, pedestrians would need to be completely re-routed. Such a decision will need to risk assessment-based.



Designated points for pedestrians to use when crossing vehicle routes. These should be clearly marked and controlled by traffic lights if necessary. Where traffic is particularly heavy, bridges or subways may be necessary.



Where vehicles pass through doorways, or under narrow bridges or through tunnels that have insufficient width to allow vehicles and pedestrians to be separated by a raised or railed-off footpath, separate access for pedestrians should be considered.

There are many situations where pedestrians and vehicles cannot be separated for operational reasons. In such situations, the following measures should be taken: 

Pedestrians may be required to wear high-visibility jackets.



Vehicles should be fitted with warning lights and alarms to indicate movement, particularly on reversing.



Structural and environmental conditions should be altered to enhance safety, with particular attention to visibility (through lighting and mirrors).

Provision of Safe Traffic Routes Workplace traffic creates a significant potential for loss, both in terms of personal injury and damage to assets. Of the many fatal accidents that occur each year involving the use of transport within workplace sites, the most common type involves victims being struck or run over by vehicles. Movement of vehicles now constitutes one of the largest single causes of deaths in factories. Ideally, to prevent such accidents occurring, the movement of vehicles should be governed by stringent rules that are enforced by management supervision and control. However, as direct supervision of site traffic is not always practicable, and as many visiting drivers may be unfamiliar with the site, the layout and design of road systems within sites is a particularly important consideration. Once a site has been built, even with due attention paid to the design, three problems always occur: 

Parking must be controlled either by making some provision for it elsewhere, or introducing an enforcement system; preferably both methods should be used.



Space is required to store returns, empties, pallets and other materials that tend to accumulate in loading areas unless specific provision is made for them.



Waste paper and cartons create problems in certain premises that can be helped by the use of skips and organised collections. However, skips use up a lot of loading area, as well as the extra space of the collection vehicle to pick up and deposit a return skip.

Road Systems Road systems should be clearly and logically arranged, allowing adequate space for movement, reversing, turning, loading and offloading. Roads should be wide enough for the safe

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movement of the largest vehicle likely to use them, with allowance made for visiting vehicles which may be larger than those used exclusively on site. Therefore, a heavily used two-way access road must be wider than one which is so lightly trafficked it is unlikely to have goods vehicles arriving and departing at the same time. The number of pedestrians and vehicles likely to be entering and leaving the site at peak time should also be considered. Other factors include: 

Surface markings on roads play an important part in regulating vehicle movements. White lines should divide access roads into lanes, indicate priorities at junctions and delineate the boundaries of parking stalls and loading bays.



As far as possible, the necessity for vehicles to reverse should be eliminated, for example, by the use of one-way systems that are clearly marked.



Hazards, such as sharp bends and blind corners, should be eliminated where possible. Where they are unavoidable, suitable warning signs and mirrors can reduce the risk. Obstacles, such as building corners, loading bay edges, low bridges and pipe-bridges, should also be clearly signed and marked.



Road junctions and road or rail crossings should be kept to a minimum. Site entrances and gateways should be of sufficient width to accommodate vehicles stopped for checking without causing obstructions on the public highway or on the site.



Physical protection of vulnerable plant and equipment such as storage tanks, pipework and storage racking may be necessary. Such plant should be located away from roads but where this is not possible, suitably constructed barriers should be provided for protection.

Minimise Reversing and Use of One-Way Systems Many fatal accidents are caused as a result of a vehicle reversing, In 1982 in the UK the HSE produced an analysis of fatal accidents due to transport activities (Transport Kills, HSE 1982), statistics showed that 20% of the fatal accidents were due to reversing vehicles. It is therefore essential to minimise reversing wherever possible. One method by which the need to reverse can be minimised is by the use of one-way systems which are clearly marked. Vehicle Parking Sufficient and suitable parking areas should be provided for all vehicles, including employees’ and visiting cars, motor cycles and cycles, waiting goods vehicles, sites for skips and pallet stacks. If any of these are left in unplanned positions, the safe operation of the site can be disrupted. Parking areas should have firm, even surfaces with adequate means of access and egress. As far as private vehicles are concerned, a site manager has only limited control over their use. Vehicles should be regulated by restricting their routes and enforcing speed restrictions, in addition to providing designated parking areas. Road Construction and Maintenance All roads should be even, constructed of suitable materials such as concrete or bituminous surfaces and well drained. Excessive gradients, i.e. in excess of 1 in 10, should be avoided where possible, although it is difficult in the vicinity of ramps that connect parts of the site which are at different levels. The provision of lay-bys and sufficient forward visibility, particularly on constricted sites, can contribute to safe vehicle movements. Maintenance of roads is particularly important, for example, potholes should not be allowed to develop, snow clearing and gritting may be necessary, and goods which fall from vehicles should be retrieved as soon as possible.

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Lighting For much of the year, parts of the working day are dark and lighting is required for safe and efficient operations, as well as for security purposes. Adequate lighting is necessary particularly at road junctions, rail crossings, near buildings and plant, in pedestrian areas and where there is regular movement of vehicles and other mobile plant. Lighting columns close to the edge of roads can cause difficulties, particularly on narrow two-way roads. If columns cannot be set back, wall-mounted lights should be considered. Speed Limits Speed limits should be set and enforced on sites. As enforcement is often difficult, speed retarders accompanied by prominent warning notices can be used to prevent vehicles being driven at excessive speeds.

Banksmen/ Vehicle Marshals As mentioned earlier in this study unit, the need for competent banksmen is paramount, especially on construction sites. A banksman stands close to a moving vehicle (usually reversing), often at some vantage point or moving about close by. He/she guides the vehicle, communicating by means of hand signals. When a vehicle is reversing, a banksman should be used to ensure safety. The banksman is responsible for ensuring that the vehicle is able to manoeuvre safely, and that the area in which the vehicle will be reversing is kept free of pedestrians. It is essential that both the driver and the banksman understand what signals are going to be used during the reversing process. The banksman should wear high visibility clothing and be visible to the vehicle driver at all times. The banksman must stand in a position that is both safe and has a good view of the entire reversing area. The banksman’s signals must be clear and visible at all times. If the driver becomes unable to see the banksman at any time, he or she should stop the vehicle immediately.

Driver Training Training needs will depend on an individual’s previous experience and the type of work they will be doing. The employer’s risk assessment should help determine the level and amount of training needed. It is likely that training will need to cover: 

General information about the job, for example, the layout of workplace routes, how and where to report faults or hazards, and accident reporting procedures.



Training and/or checks to ensure that individuals can carry out their work duties safely. For a driver this is likely to include information and instruction on how to operate the vehicle, daily and weekly vehicle checks (e.g. ensuring lights work, no obvious faults, driver controls operating correctly, etc.) information about particular hazards, speed limits, the appropriate parking and loading areas, etc. It may be necessary to test trainees on site.

It is important to stress to individuals the risks associated with unsafe working practices, for example: driving too fast, turning too sharply, or driving on unsafe gradients. Particular attention needs to be given to younger people, as they are more likely to be unfamiliar with a work environment, their perception of risk is likely to be lower and are still developing maturity. A planned programme of refresher training will usually be necessary for all drivers to ensure their continued competence.

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A licensing or authorisation system can be used to check that employees are trained and competent. The licence is often a simple document with details of the types of vehicles that a person is competent to operate.

Signage It should never be assumed that people in the workplace will be automatically aware of the hazards around them and understand the necessary preventative and protective measures in place. It is important, therefore, that all persons are given appropriate information to enable them to move around the workplace in safety. Instruction should be given as to general conduct, such as not running or playing games, as well as in respect of particular hazards. Part of this will be in the form of signs, markings and notices, but additional information may also be necessary, for example, about keeping to designated walkways, being aware of particular hazards (such as temporary work going on overhead), etc. Visitors to premises may need special instruction prior to entry. Clearly visible and easily understood signs, markings and notices must be provided to ensure that pedestrians, however unfamiliar they may be with the situation, are aware of any hazards and what they must do to avoid them. Signs must be used in respect of: 

Prohibitions – for example, no pedestrian access, no entry through a particular doorway, no smoking or no naked lights in particular areas, etc.



Warnings – for example, in respect of dangers from falling objects or hazardous substances, reversing vehicles, forklift operations in progress.



Mandatory actions – for example, compulsory wearing/use of personal protective equipment in an area including; seat belts, hearing protection, etc.



Safe conditions – for example, emergency exits, fire escape routes, locality of first aid points, etc.

To ensure that hazards are easily identifiable it is advisable to mark the area with hazard warning tape, the standard style of the warning is yellow diagonal stripes on a black background. This warning should be fixed by tape or painted onto any object likely to present an unforeseen hazard. Examples include the edges of steps, overhead obstructions and cables or pipes temporarily laid across a floor. In addition, hazard markings on floors should indicate areas to avoid, such as around doors used by vehicles, and delineate the edges of safe walkways. Signage should not only be provided to warn pedestrians of the hazards in a particular workplace. It is important to inform those driving workplace vehicles of particular hazards, (e.g. pedestrians crossing a roadway, height restrictions, no go areas, etc.). In such instances signage could come in the form of prohibition speed limit signs, mandatory signs requiring drivers to use their horn when approaching a certain area, warning signs to forewarn drivers of height restrictions, etc.

Safe Use of Mobile Equipment Roll Over and Falling Object Protection In general, passengers must be prohibited from being carried on mobile work equipment unless specific arrangements are made to allow people to be carried safely, i.e. provision to prevent passengers from falling off or coming in contact with parts of the equipment likely to cause injury.

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If there is a risk of mobile work equipment tipping over and causing injury to the driver or passengers then roll over protective structures (ROPS) should be fitted. If it can be shown that it is unlikely that the equipment will tip by no more than 90° due to the nature of the construction, e.g. a vertical masted forklift truck, then a ROPS need not be fitted. If, however, there is a risk of material falling on the driver or passengers when the equipment is in use, then a falling object protective structure (FOPS) should be fitted. This could be achieved by a strong cab or cage which should be certificated for specific machines (see figure that follows).

Compact Tractor Fitted with a Back-Actor and ROPS Telescopic Forklift Truck fitted with ROPS and FOPS Seat Belts Where there is the possibility of the driver being crushed between any part of the truck or tractor fitted with a protective framework and the ground, then a driver restraining device (seat belts) should be fitted. This is more likely to occur when ‘open’ cages or roll bars are fitted, as opposed to enclosed cabs. Lighting If the equipment is expected to work in the dark or in poorly lit conditions, it must be fitted with appropriate lights, irrespective of whether it will be used on the public highway or not. Specific lighting will, of course, be required if the equipment is taken on the public highway. Drivers The following points need to be considered when selecting people to drive or operate workplace transport: 

Drivers should be competent in the safe operation of the vehicles and their daily maintenance checks.



Training certificates should be checked for validity.



Drivers should be in possession of a driver’s licence, or industry specific certification and accreditation under a relevant scheme.



Caution should be exercised with drivers who may be unfamiliar with the hazards of the site, including new or inexperienced staff.

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

No one unfit to drive through the influence of alcohol or drugs should be permitted to drive any vehicle.

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Occupational Driving It has been estimated that up to a third of all road traffic accidents involve somebody who is at work at the time. This may account for over 20 fatalities and 250 serious injuries every week. Some employers believe, incorrectly, that provided they comply with certain road traffic law requirements, e.g. Company vehicles have a valid test certificate, and that drivers hold a valid licence, this is enough to ensure the safety of their employees, and others, when they are on the road. However, health and safety law applies to on-the-road work activities as to all work activities, and the risks should be effectively managed within a health and safety management system. Guidance, available from the HSE in the UK and other sources, should be used by employers, managers or supervisors with staff who drive, or ride a motorcycle or bicycle at work, and in particular those with responsibility for fleet management. This guidance should also be used by self-employed people. The guidance covers people whose main job is driving, and those who drive or ride occasionally or for short distances. Health and safety law does not generally apply to commuting, unless the employee is travelling from their home to a location which is not their usual place of work.

Occupational Driving Hazards Occupational driving poses many problems to employers and their employees, the biggest being road traffic accidents which could lead to:—

Death or injury of employee.

—

Death or injury to members of the public.

—

Damaged vehicles and associated costs.

—

Lost working days due to injury or ill health of employee as a result of the accident.

—

Increased risk of stress and poor morale.

—

Costs associated with investigating and reporting incidents.

—

Missed orders and risk of loosing goodwill of customers.

Causes of Driving Accidents When considering the causes of accidents the following factors can be considered:-

The Driver The competence of a person will greatly affect their ability to drive safely. A person with no previous experience will have a low perception of hazards and risks that may affect them and third parties. In addition a person’s age, level of training or knowledge, or lack of awareness of organisational policies will affect their level of perception of hazards and risks of driving. Research conducted by the HSE in the UK shows that younger drivers are at greater risk and showed an increased level of social deviance and traffic violations, whereas older drivers tend to be more likely to suffer from visual impairments and drowsy driving. Tiredness and fatigue can affect all drivers. Poorly planned and long journeys, driving at night, heavy workloads, tight deadlines, alcohol consumption, medication and general health can contribute towards accidents occurring due to driver fatigue or tiredness.

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The Vehicle Using vehicles for purposes for which they are not intended or using poorly maintained vehicles will inevitably result in vehicle failure and/or an accident. Older vehicles may be less reliable and show rapid deterioration requiring a much higher frequency of maintenance. Safety features (seat belts and air bags) and other vehicle functions (lights, windscreen wipers and tyres etc.) may experience damage or deterioration through general wear and tear and eventually fail. Overloading or incorrectly loaded vehicles also pose a risk of vehicle damage or failure.

Organisational Factors Organisations that do not have a road safety policy are likely to have a higher accident frequency rate compared to those that do. Without a policy employees lack clear instruction and awareness of risks involved with driving. Inattention and distraction are two of the most common causes of road traffic accidents. The use of hand held and even hands-free mobile phones provide enough distraction to alter a driver’s behaviour but are often given to employees for the purpose of being able to make and receive calls in their vehicle. The use of hand-held mobile phones or other hand-held devices prevents the driver having full physical and mental control of the vehicle increasing the risk of an accident due to lapse in concentration. Even during conversation on hands-free mobile phones, driver’s speed may significantly drop or raise and vehicles have been seen to veer off the road or lane whilst the driver is using the telephone. Generally the concentration of a person drops when there are too many factors on which to focus. Other distractions may be caused by other auditory means such as music or passengers.

Environmental Conditions Weather conditions can play a large part in determining whether an accident occurs, and if so the scale of it. Snow, heavy rain and strong winds will create slippery ground conditions, instability of a vehicle and poor visibility. The weather may also damage road surfaces and after excessive rain flooding may occur. The sun can create blind spots or the inability to see if extremely bright or low in the sky. Even with a competent and trained driver these conditions can create additional pressure and test their ability. Road conditions may vary on different routes. Road repairs and works may affect the standard and condition of a road making it uneven or hazardous. Where such routes are regular driver complacency can contribute to an accident.

Reducing the risks from Occupational Driving Occupational driving can only be effectively managed if it is integrated into your arrangements for managing health and safety at work. Employers should look at existing health and safety management systems and arrangements and consider whether they adequately cover road safety. All organisations must ensure that their health and safety policy statement covers occupational driving. As a minimum the policy should include compliance with road traffic legislation, rest breaks the use of mobile phones and hand-held devices, vehicle maintenance and driver competence. Employers need to be committed to providing work-related road safety management systems and be aware of their responsibilities and how to achieve an adequate system. Employers must conduct a road safety risk assessment to identify the hazards involved with driving. By

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identifying the hazards, evaluating the risks and existing precautions, the employer will be able to understand the causes of accidents, and develop and implement suitable control measures. Before employers can start to reduce the risks associated with occupational driving they must complete a risk assessment to identify the hazards involved. Once employers have identified the hazards from the risk assessment it will enable them to implement the correct management controls that will reduce the likelihood of an accident. There are a number of actions that employers can take to reduce this risk:-

The Driver Employers must ensure that all drivers hold a valid licence and relevant insurance for the vehicle which they will be required to drive. Employees with previous experience of driving certain vehicles will demonstrate a higher competence, than those with no previous experience. Competence can be further developed with training. Training should include how to check the general features of the vehicle, particularly safety features, as well as specific vehicle limits, such as loads and loading procedures. Fitness and health checks, including eyesight tests, should be conducted to ensure all drivers have the physical requirements for occupational driving. Tiredness and fatigue are more difficult to control. The employer can train and instruct the employee, lay down procedures in the driver handbook and company policy (discussed later in this chapter) and set a driving schedule or timetable to prevent driver tiredness. However, tiredness and fatigue may result due to personal ‘out of work’ circumstances which the employer has either any knowledge or control of. Drivers must take some responsibility for themselves and must be sure to take rest breaks whenever they are needed. All journeys must be planned to incorporate regular breaks and if drivers should feel overcome with tiredness or fatigue they should not drive. The employer must be vigilant and conduct regular health checks and try to introduce arrangements for monitoring employees compliance with company policy to ensure drivers have the physical and mental capability that is required for safe driving.

The Vehicle Employers must provide vehicles which are fit for the purpose of which they are intended. All vehicles must be serviced regularly so any repairs or deterioration can be spotted at the earliest opportunity. It would be a benefit for drivers to be trained to carry out daily checks and any minor repairs, such as changing a wheel, should the need arise. Vehicles displaying load limits, loading and securing instructions will provide a reminder and warning to those involved.

Organisational Factors Organisations should develop health and safety policies that cover occupational driving. It could be that a separate ‘road safety’ policy is developed which contains information that will raise the awareness of the risks involved in occupational driving, and the company procedures which must be complied with. The policy must be communicated to employees clearly stating instructions and procedures for them to follow. The policy should reinforce road safety legislation, in particular the use of seat belts and mobile phones, being under the influence of alcohol or drugs, and complying with speed limits. The policy must clearly state that the use of hand-held mobile phones and other hand-held devices is illegal and it is suggested that even the use of hand-free mobile phones should be prohibited due to the distraction they create. People may be able to concentrate on driving, concentrate on an intense conversation and perform fine motor skills (like operating the vehicle controls or keying in telephone

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numbers into a mobile phone) and but cannot do all three at the same time to the level that is required for safe driving. The policy should instruct drivers not to answer any calls whilst driving or to keep the phone turned off to avoid distraction. Calls should be taken when in a suitably safe area and when stationary. The policy must inform all other employees not contact any colleague whom they know may be driving. The policy might also include procedures for driving times, mileage limits, rest breaks, journey scheduling and planning, and highlight any other applicable road safety legislation. In addition to the road safety policy, driver handbooks are another way of communicating safe driving guidance.

Environmental Conditions Careful consideration must be given when planning the routes and times of journeys. Where adverse weather conditions are likely to jeopardise the safety of a driver the journey should be rescheduled. Vehicles must also be properly equipped to operate in poor weather conditions as well as additional driver training for such circumstances. Emergency procedures must be in place should the driver become stranded by weather conditions or other means. Road works or repairs, low level bridges, tunnels and level crossings are other factors that must be considered when planning a journey to prevent additional risk of harm arising.

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BSC Awards International Diploma | Unit 1 Element 1B: Applied Health and Safety Management


Title

Page

Mechanical Handling and Lifting Operations

TYPES OF MECHANICAL HANDLING AND LIFTING EQUIPMENT......................................................................... 3 CRANES .............................................................................................................................................................. 3 LIFTS AND HOISTS ................................................................................................................................................. 6 LIFT TRUCKS ........................................................................................................................................................ 7 ATTACHMENTS ...................................................................................................................................................... 7 MAIN CAUSES OF FAILURE OF LIFTING EQUIPMENT ....................................................................................... 10 POOR MAINTENANCE/ INSPECTION ............................................................................................................................ 10 POOR SELECTION ................................................................................................................................................. 10 LACK OF PLANNING ............................................................................................................................................... 11 LACK OF SUPERVISION AND TRAINING ........................................................................................................................ 11 CONTROLLING THE RISKS FROM LIFTING OPERATIONS ................................................................................. 12 STRENGTH AND STABILITY ...................................................................................................................................... 12 POSITIONING AND INSTALLATION ............................................................................................................................. 13 ORGANISATION OF LIFTING OPERATIONS .................................................................................................................... 13 THOROUGH EXAMINATION AND INSPECTION ................................................................................................................. 14 FORKLIFT TRUCK SAFETY ................................................................................................................................. 15 PRINCIPLES OF BALANCE ........................................................................................................................................ 15 VARIATIONS OF LIFT TRUCK .................................................................................................................................... 15 TYPES AND CAUSES OF INSTABILITY .......................................................................................................................... 16 SIGNIFICANT HAZARDS .......................................................................................................................................... 16 CONTROLLING RISKS FROM FORKLIFT TRUCKS .............................................................................................................. 17 GENERAL PRINCIPLES ............................................................................................................................................ 17 SELECTION OF FORKLIFT TRUCK ............................................................................................................................... 18 DRIVER TRAINING ................................................................................................................................................ 18 VEHICLE MAINTENANCE AND INSPECTIONS .................................................................................................................. 19


BSC Awards International Diploma | Unit 1 Element 1B: Applied Health and Safety Management Study Unit 1B7 | Mechanical Handling and Lifting Operations Learning Outcomes When you have worked through this Study Unit, you will be able to:

1.B.7.1 Outline the main types of mechanical handling and lifting equipment 1.B.7.2 Outline the main causes of failure associated with mechanical handling and lifting equipment 1.B.7.3 Describe the main hazards associated with mechanical handling and lifting operations and explain how they may cause harm 1.B.7.4 Determine, implement, evaluate and maintain measures for controlling risks from mechanical handling and lifting operations 1.B.7.5 Apply the principles of fork lift truck safety

Unit 5:

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Types of Mechanical Handling and Lifting Equipment There is a wide range of equipment available for carrying out operations for lifting and moving loads. They range from small pedestrian operated trucks and trolleys to large cranes and hoists. In this chapter we will focus on the more significant and hazardous lifting equipment.

Cranes Mobile Cranes These are the most common types of cranes in use (see figure below). The crane on the left is a rough terrain wheeled crane with a telescopic jib. Such cranes are very mobile and suitable for small lifts, making them useful around a construction site.

Mobile Road or Rubber Wheeled Cranes The bigger road mobile cranes have a large chassis and either a lattice or a telescopic jib. They are normally available from the hire company who will provide the design and/or check the lift. They are normally used for the single large lift, as the erection and dismantling time is often far longer than the lift time itself. Road mobiles normally have outriggers fitted. They extend from the chassis of the crane and are used to support the weight of both the crane and the load, lifting the running wheels clear of the ground. When using the outriggers, it is important to realise that whilst their use can increase the capacity of the crane, they increase its size. The outriggers must be on firm foundations such as solid timber packing, steel plates or even specially cast concrete pads.

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EFFECTIVE AREA WITH OUTRIGGERS

BASIC AREA OF BASE

Outriggers

Tower Cranes These consist of a tall, slender lattice mast with a jib unit at the top. They are used on long duration work where large areas of access are required to be covered with the loads. Various types are available for special situations. They are normally fixed to one location but can be mounted on rails. Due to the height of the crane, Tower cranes are normally erected with the use of other cranes. Tower cranes offer the following advantages and disadvantages: 



Advantages −

Small base with relatively large working area.

−

Stable as considerable care is taken to install.

−

Good visibility of the load and work area.

Disadvantages −

High winds can be a problem, as they can cause instability of the load.

−

Workers may not always be aware of a load overhead.

Mobile cranes offer the following advantages and disadvantages: 



Advantages −

Suited to short-term contracts.

−

Lower transport costs.

−

Quicker set-up.

Disadvantages −

Instability due to less certainty of ground make up.

−

Greater potential for striking structures due to poor reach over building roof edges.

−

Greater potential for contact with overhead power lines due to increased mobility.

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Bogies

Ballast

Fixed tower

Hook

Saddle

Jib head

Saddle or trolley

(a)

Minimum hook radius

Jib

Jib foot Slewing ring Tower head

Jib

Sleepers

Rail

Counterbalance and ballast Bogies

Slewing ring

Slewing tower

Jib

(b)

Minimum hook radius

Tower Cranes: (a) Saddle-Jib Type with Fixed Tower; (b) Luffing-Jib Type with Slewing Tower

Sleepers

Rail

Counterbalance

Counter jib Slewing ring

Counterbalance

Cab Counter jib

Cat head

Jib tie




Overhead (Gantry) Cranes These are a version of gantry cranes used generally within buildings, although they can be found in outside situations. (Gantry cranes consist of a framework of two vertical supports connected with a horizontal beam or lattice along which a trolley moves. The bases of the uprights have wheels fitted that run on railway tracks, allowing the gantry to move backwards and forwards.) The verticals of the frame are omitted, the rails being attached to the structural steel framework of the building or on columns outside at a high level. Overhead cranes are common in engineering works and plants where lifting access for conventional cranes is difficult due to the layout (e.g. in power stations, to lift out turbines for maintenance). Capacity can be very high (200 tonnes is not unusual) and they are usually designed for a specific location.

Crawler Cranes Crawler cranes are suitable for long duration operations and 'pick and carry' duties, and for use on some types of terrain where a wheel-mounted crane would not be appropriate. They are particularly useful on rough terrain, as they have a caterpillar track system, similar to army tanks, which allows them to travel more easily in areas where conventional wheels and tyres would get stuck. Mini crawler cranes can be used for interior work where floor loading has to be low, and in other restricted access and confined working environments. Many have joint fuel operations – petrol, LPG and mains electric – which means that pollution and fumes in confined areas are limited.

Lorry Loader Cranes Lorry loader cranes generally consist of a hydraulically-powered, articulated arm that is fitted to the trailer of the truck, just behind the cab. This arm is used to load goods on to and off from the trailer or lorry. Warnings have been issued in the UK recently regarding this type of crane, following a number of incidents that have occurred in the UK, including a fatality. Lorry loader cranes rely on the lorry's chassis for support and must therefore have stabilisers deployed to prevent overturning. New lorry loader cranes must be fitted with an interlocking system, or equivalent engineering solution, that will prevent the crane from operating without the stabilisers being deployed.

Excavators Used as Cranes Hydraulic excavators can be used as cranes for lifting and moving material, and are routinely used on jobsites. When using excavators for this purpose, the same attention to detail must be used as when using any other crane, as similar risks exist. For example, the lift capacity of an excavator changes radically as the load position varies. It is therefore important, before lifting, to determine where the machine will be least capable, and to decide whether the lifting capacity at that point will in fact be sufficient to handle the load safely.

Lifts and Hoists These cover any equipment used in a static location for raising or lowering a load – goods or people – where the direction of the movement is constrained by guides, tracks or other forms of containment. There are many examples, such as passenger lifts in buildings, hoists used for assisting hospital patients into a bath, window cleaning cages on high buildings, hoists and lifts for moving materials up structures on building sites, etc. The difference between the two is that lifts have some form of cage or walls around a platform, whereas a hoist will have an open platform.

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The styles and types vary according to the work and the work environment. The simplest form of hoists are the cantilever type used on construction sites where a rope passes over a pulley at the top of the structure, with the lifting power being supplied by a machine or manually powered winch.

Cantilever Hoist More sophisticated systems use geared drives to control lifting and reinforced cables rather than ropes. There are also rack and pinion drives, where the drive turns a small cog whose teeth engage with similar teeth on the pinion. These are extensively used for passengercarrying hoists and for inclined hoists and lifts, and are carrying considerable weights over extensive distances. The interlocking of the cogs act as an effective brake and control over the movement.

Lift Trucks Lift trucks are a very flexible class of mobile handling equipment designed for use within and around buildings. They can cope with a variety of materials and come in a range of different guises. They are used to lift, move and restack palletised loads and may be fitted with a variety of attachments including drum-handling equipment, bale clamps, working platforms, skips, fork extensions and lifting appliances, all of which increase the versatility of the vehicle. Further details later in this section.

Attachments Chains These, along with other types of slings, strops, etc. give a strong, flexible link between the load and the crane. They are usually used in conjunction with shackles (see later in this section). Chains of varying sizes and makes are widely used for lifting purposes. Wrought iron chains are still found in industry although their manufacture has virtually ceased. They provided a very good system for carrying heavy loads and had considerable resistance to damage by corrosive atmospheres. They suffer a serious disadvantage in that they become work hardened in use. Work hardening is a process which causes changes in the crystal structure of wrought iron, making it brittle and therefore susceptible to brittle fracture. All wrought iron chains must undergo periodic annealing. Wrought iron chains may be identified by the scarf weld at the end of each link.

Fibre Ropes The term "fibre rope" is a general expression which covers natural or man-made fibre ropes. It is now possible to select a suitable rope from the different strengths and properties of the

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material available to suit most purposes. As there is no official test certificate for ropes, it is very important that ropes are obtained from a reliable source where adequate quality control during production, and testing of the final product, are carried out, and where reliance can be placed upon the manufacturer's new rope test certificate. It is therefore important to have a visual inspection regime in place.

Shackles These come in a variety of types and sizes, some common examples being 'D' shackles (because of their shape) and bow shackles. These are passed through the eye of the sling or strop and are connected to the load by means of a pin, often threaded.

Eye Bolts These are threaded bolts which have an eye formed at the other end. These are used where there are dedicated lifting points on the load that have been drilled and threaded. They are used in conjunction with shackles.

Slings •

Two, Three or Four Legged Slings Normally made of steel wire rope, slings usually have a large ring at one end to fit onto the hook, whilst at the other end there are eyes that allow the use of shackles (see figures that follow).

Care must be taken when using any sling that the angles between the legs do not exceed the stated angle. E.g. SWL 5 tonnes 0°– 45°.

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Two, Three and Four Legged Slings A good guide to the safe condition of a wire rope is the number of broken wires which are visible. In a length of rope ten diameters long there should b be e no more than 5% of the total number of wires broken. •

Endless Slings A common type of lifting tackle, this is often made of webbing material or nylon, and is a continuous loop. It is passed under the load and simply slipped onto the hook (often in tandem). ). Care must be taken when using this type of sling that it does not pass over any sharp edges and, if necessary, padding should be used to protect the sling.

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Main Causes of Failure of Lifting Equipment The principle causes of failure, including loss of a load are:

Overloading One of the fundamental causes of the failure of lifting equipment is as a result of exceeding the safe working load (SWL). Consequently, all lifting equipment must be marked to indicate the SWL. This also includes accessories for lifting loads. In the case of cranes, the SWL depends on the configuration of the equipment and, therefore, load radius is a key consideration. To prevent overloading, cranes must be fitted with load indicators and load radius indicators that show the radius that the crane is working at as well as the safe load for that radius. They must also be fitted with an automatic safe load indicator that gives a visible warning when the SWL is approached, and an audible warning when the SWL is exceeded. Lifting equipment, such as cranes and telescopic handlers, where the 'reach' can vary should be fitted with rated capacity indicators and limiters giving either audible or visual warning to the operator when safe limits are exceeded. Forklift trucks must be fitted with capacity plates to indicate the safe working loads. The rated capacity of a forklift truck is the maximum weight (kg) at a maximum load centre (m), measured from the heel of the forks. Any increase over the rated capacity will cause overloading, and therefore it is essential that this information is displayed on the truck itself. Overloading of lifts or hoists can cause the supporting ropes or winding mechanism to fail, and the platform or cage fall to the ground. Consequently, lifts and hoists must display the SWL and/or maximum occupancy.

Poor Maintenance/ Inspection Maintenance and inspection of lifting equipment is such an important safeguard for thorough examination: when lifting equipment is used for the first time by that employer; when certain equipment is installed; periodically during the lifetime of equipment; and following exceptional circumstances. Inspections are required, and should be carried out by a competent person and include visual and functional checks. Any failure to regularly maintain, examine and inspect lifting equipment is likely to lead to deterioration of the integrity of the equipment and significantly increase the likelihood of failure.

Poor Selection Firstly, a crane must be selected which is suitable for the job. Cranes come in a variety of types, sizes and capacities. The selection of the appropriate type of crane will depend upon the following factors: 

Weight and dimensions of loads.



Heights of lifts and distances or areas of movement of loads.



Number and frequency of lifts.



Length of time the crane will be required.



Site ground conditions.

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

Space available for crane access, erection, operation and dismantling.



Other special operational requirements (e.g. adjacent operations).

The capacity of a crane is its maximum lift in perfect conditions. Built into the capacity is a factor of safety that a competent person may increase (thus reducing the maximum load capacity) if circumstances are less than perfect.

Lack of Planning Planning should include: 

Correct crane selection (weight of load, radius of operation, height of lift).



Correct siting (firm ground, clear of obstructions).



Adequate stability (guy ropes, bolting, counterweights, outriggers).



Consideration of the whole lifting operation and, in particular, slinging methods and the route of the lift.

Lack of Supervision and Training In order to ensure that the lifting operation is carried out according to the plan, staff must be adequately supervised and properly trained to ensure competence: Lifting Operations ‘Appointed Person’

The ‘appointed person’ should have undergone formal training in how to plan lifting operations safely and have relevant experience with lifting operations. Lift Supervisor

The lift supervisor is normally a foreman or team leader with experience of lifting operations who will ensure that the lifting plan is followed, ensuring the necessary controls are in place to prevent failure of the lift. He should be authorised to stop the lift if controls do not address the risks fully. Slinger/Signaller

The slinger/signaller’s relative experience is assessed by the lift supervisor in relation to the proposed lifting operation to be carried out as to whether sufficient experience has been attained. The slinger/signaller should have been formally trained and have a valid certification card or similar. He is responsible for attaching and detaching the load and guiding the load by giving appropriate signals to the plant operator. Plant Operator

The plant operator is responsible for the lifting equipment serviceability and operating in a safe manner as he has been formally been trained to do. The plant operator should have a valid certification card or similar for the item of plant being used e.g. crane, forklift truck, telescopic handler etc. This can include International Powered Access Federation (IPAF) cards for operators of mobile elevating work platforms.

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Controlling the Risks from Lifting Operations The principle objective is to remove or reduce the risk to the health and safety of those who use, or are affected by lifting equipment and its operation. Generally, this requires that lifting equipment provided for use at work be: 

Strong and stable enough for the particular use and marked to indicate safe working loads.



Positioned and installed to minimise any risks.



Used safely, i.e. the work is planned, organised and performed by competent people.



Subject to ongoing thorough examination and, where appropriate, inspection by competent people.

The following specific requirements should be complied with:

Strength and Stability Where lifting equipment is likely to be affected by high winds, e.g. tower cranes, then devices should be fitted to detect wind speed, usually by means of an anemometer, so that operations can be postponed when situations become dangerous. Particular attention must be given to ensuring that the equipment is sufficiently strong and stable for the lift. These arrangements extend to and include ensuring that equipment and lifting accessories are marked with the safe working load (SWL) dependent upon the operating configuration. This could be in the form of a tag, an indicator plate or a chart, which is readily available to the operator. Stability of the equipment will depend upon ground and surface conditions, as well as the effects of the load reach and wind. Outriggers, stabilisers, counterbalance weights and anchorage systems can all be used to maintain or improve stability. Lifting equipment, such as cranes and telescopic handlers where the 'reach' can vary, should be fitted with rated capacity indicators and limiters giving either audible or visual warning to the operator when safe limits are exceeded. Lifting equipment and attachments should be sufficiently robust to withstand stresses induced at mounting and fixing points.

Equipment for Lifting People Employers must ensure that all lifting equipment that is used for lifting persons: 

Can not crush, trap, or allow a person to fall from the carrier.



Has adequate and suitable devices to prevent the carrier from falling.

Design

Hoists or lifts used for carrying persons must be fitted with an automatic limiting device to prevent the cage overrunning, at least two suspension ropes capable of taking the maximum working load, and safety gear that will support the cage with its maximum working load in the event of the suspension ropes failing. Examination and testing should be carried out every 6 months. Lift trucks can be modified and fitted with a working platform for use as a place of work or to transfer people from one level to another. In such cases, the safeguards should include:

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

Secure attachment to the lift truck.



Clear marking of the maximum allowable load.



Raising and lowering controlled by the person on the platform.



Toeboards and guardrails.

Positioning and Installation Employers must ensure that the positioning and installation of lifting equipment is conducted in such a way as to reduce the associated risks. The positioning of the equipment must also ensure that the risks posed from the load are reduced, so that it cannot drift, fall or be unintentionally released. It is important that loads are lifted in such a manner as not to lift them over people. Lifting equipment should be positioned or installed to prevent crushing when operating in its most extreme positions. Any loads such as hoists or lifts moving along fixed paths should be protected by a suitable and substantial enclosure or other suitable protective measure.

Equipment Markings Lifting equipment must be clearly and suitably marked to indicate safe working loads (SWL). The set up and configuration of certain lifting equipment may vary and therefore the marking of safe working loads must reflect this. For example, a crane must be clearly marked with its maximum lifting load limit. However, the configuration of some cranes will allow for a series of maximum lifting load limits depending on the counter-weights fitted. On accessories such as shackles, chains and wire slings, the SWL should be marked legibly and indelibly on a durable tag or label attached to the sling, or marked on the ferrule or master link. Lifting equipment that is designed for lifting persons must be marked in a way that specifies the characteristics necessary for its safe use. In practice, this means indicating the maximum number of persons that can be safely carried. Lifting equipment, such as fork lift trucks, which are not designed to lift people, must be clearly marked to highlight that it is not suitable for doing so.

Organisation of Lifting Operations Planning

Lifting operations should be planned by a competent person, appropriately supervised and carried out in a safe manner". Where routine lifting operations are carried out, e.g. the use of a forklift truck, it is acceptable that a trained and certified operator should be sufficiently competent to assess the conditions and complete the operation. Lifting equipment may not be used to lift people unless a specific assessment has been carried out confirming its suitability. It should then be clearly marked indicating the number of persons that it is safe to lift. People should never be lifted or carried on the forks of a lift truck unless purpose built platforms are used which are adequately fenced to prevent passengers from falling or being trapped by the lifting mechanisms. The platform should be effectively secured to the forks or the backplate and any tilt mechanism, particularly on telescopic handlers, must be limited or locked out. Particular effort must be made to ensure loads are not carried or suspended over areas where people are present and care must be taken to avoid loads, booms or counterweights colliding with other equipment.

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Supervision

The amount and quality of supervision should be proportional to the risk, and take account of the people involved, for example, an experienced forklift truck driver doing a routine job would not require much supervision. Supervision does not necessarily mean the direct physical presence of a supervisor at all times.

Thorough Examination and Inspection A "thorough examination" of all such equipment is to be carried out at defined minimum intervals. The thorough examination must be conducted by a competent person with the experience, knowledge and skills to assess the condition of the particular equipment. The general requirements are that: 

When any lifting equipment is used for the first time, or the first time it is used at a new location, it must be thoroughly examined for defects and to ensure that it has been correctly installed.



Thereafter, a similar thorough examination must be conducted at least every six months in the case of equipment used for lifting people and lifting accessories, or every twelve months for all other types of lifting equipment.

The employer must have a written scheme for ensuring that these requirements are carried out. In addition, further examinations must be conducted whenever there has been a change in the conditions affecting the lifting equipment such as may affect the safety of its use.

Reports and Defects Where an inspection or examination identifies a defect in the equipment that could result in injury to people, that defect is to be reported immediately to the employer. As soon as possible thereafter, the full findings from the examination/inspection must be presented in writing. Where there is an existing or imminent risk of serious personal injury, the report must also be presented to the relevant enforcement authority. If notified of a defect, the employer must not allow the equipment to be used until the defect has been rectified (and, by implication, there will need to be a further examination to ensure that the equipment is then safe to operate). The latest report in respect of each piece of lifting equipment must be kept for inspection by the enforcement authorities if required.

Keeping of Information Where an employer obtains lifting equipment, he/she should make sure that every examination report conducted on lifting equipment is kept available for inspection. It would be considered best practice to keep lifting equipment reports for as long as the equipment is in use.

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Forklift Truck Safety Principles of Balance The mass of a counterbalanced lift truck acts as a counterweight so that the load can be lifted and moved without the truck tipping. However, the truck can be tipped over if overloaded, if the load is incorrectly placed on the forks, or if the truck is travelling across an incline or an uneven surface. Instability is increased if the truck travels with the forks raised rather than lowered. Carrying heavy loads while travelling forward down a slope will also increase the likelihood of tipping.

Load

Counterbalance

Fulcrum

LOAD COUNTERBALANCE FULCRUM

Variations of Lift Truck Rough Terrain

Rough terrain trucks are designed to operate on uneven surfaces such as those encountered on construction sites. However, care is needed on rough ground as bouncing can cause loss of control. The trucks should not be used for lifting to high levels unless the ground is reasonably level and consolidated, and the truck is clear of excavations and walls. Unless specially designed, they should not be used for stacking on inclines.

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Telescopic Materials Handlers (Narrow Aisle Trucks)

This type of forklift truck operates up to a height of 12 metres. They work in narrow aisles, but can also move outside the aisles. They must operate on high grades of flooring, that is very level and smooth to avoid bumping or wobbling, because of the lift height. Some have the operator at ground level, while others have a rising cab. The operator can access the stack on either side of the aisle by using a mast that turns to left or right (multi-directional). Side Loading Trucks

This is a form of forklift truck is commonly found in timber yards. It is a type of reach truck used to carry long lengths of timber. Pedestrian Controlled Trucks

These trucks are operated by a pedestrian via a control handle. Operators should always face the direction of travel and not walk backwards nor directly in front of the control handle, which should act as a ‘dead man’s handle’ upon release by the pedestrian in the event of an emergency.

Types and Causes of Instability Instability is one of the major problems involved in the safe use of vehicles. There are two main ways in which a vehicle may become unstable: 

Lateral instability is where a vehicle will tip over onto its side. An example is when a lorry is blown over in a high wind or a loaded forklift tips while driving across a slope.



Longitudinal instability is where a vehicle tips over forwards or backwards. An example is when a forklift truck tips forward because too much is loaded on the forks.

Loss of control also occurs when the wheels lose grip on a road surface. Examples include skidding on an icy road, or when a forklift truck hits a pothole or other obstruction.

Significant Hazards The biggest problem with lift trucks is that, with their small wheels and particularly when loaded and with the forks raised, they may become unbalanced. This may result in the load being shed or the whole truck tipping over. Other hazards that arise from the lift truck itself include: 

For electrically operated trucks, there is the danger of production of hydrogen gas whilst charging the batteries, as well as the manual handling implications of changing them.



For gas (LPG) operated lift trucks, there is a fire and explosion risk, particularly during the changing of cylinders.



Hazards arise from poor maintenance of brakes, steering, tyres, lights, etc., and emission of substances whilst being used, i.e. exhaust gases, including diesel fumes in confined spaces.

There are hazards that arise from the operator or the manner of operation of the truck. For instance, a driver may drive too fast or attempt to corner at speed, and so cause the vehicle to overturn or lose its load. Such issues may be aggravated by the youth or inexperience of the operator. A younger may tend to drive faster and not pay attention to the need to drive with caution, and may need specific training and supervision to guard against this.

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The area of operation of the lift truck may also present hazards. For example, lift trucks are often used in areas where there is a possibility of pedestrian movement. Impact with people as well as with structures such as walls and racking is a constant hazard. Driving over unsuitable ground can cause the load to shift or fall off. Other hazards arise from: 

The need to reverse in many situations, with consequent visibility problems.



A raised load obscuring the view of the operator.



Unsuitability of the truck for the working environment - for example, not being designed for the particular loads, diesel-powered trucks with heavy exhaust fumes being used in poorly ventilated areas (such as basements), counterbalanced or reach trucks being used on rough terrain (such as construction sites).



Overloading of lift trucks can lead to loss of control in steering and braking, and unevenly or improperly loaded lift trucks can become unstable.

Controlling Risks from Forklift Trucks General Principles Noting the factors that affect vehicle stability discussed earlier, the workplace should be properly laid out. As far as possible, surfaces should be even and level (no potholes, sudden dips, etc.) and slopes should be minimised. As far as possible, pedestrians should be segregated from vehicles with properly signed traffic routes and barriers. Particular points to note are: 

Care should be taken in the vicinity of pedestrians and, as a general rule, drivers should keep to the left. However, in restricted areas where visibility is poor, a central rather than a left-hand side position may improve visibility. Prescribed lanes or routes should always be used.



The horn should be sounded at every potential danger point, such as before entering doorways and at blind corners, although the use of a horn does not give the driver right of way.



Trucks should not run over cables or pipes unless they are suitably protected to prevent mechanical damage.



Violent braking of a loaded truck should be avoided as sharp movements could cause the load to fall off or the truck to tip.



Wherever possible when driving, the forks should be lowered to within 150 mm of the ground and the mast tilted back. Driving with the load elevated increases the risk of overturning.



When a high load restricts vision, the truck should be driven in reverse except when driving up an incline.



A load should not be picked up if someone is standing close to it, and people should not walk or stand beneath a load when it is elevated. Loads that are unsuitable or pallets that are damaged should not be picked up and further advice should be sought.



When loaded and travelling up or down gradients, the forks should face uphill. When unloaded and travelling down gradients, the forks should face downhill. At the bottom of the gradient, the forks may require lifting slightly to prevent contact with the ground.

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

Trucks must be driven at an appropriate speed for the conditions and visibility. Where speed restrictions have been set, they must be obeyed. Particular care must be taken when reversing.



Before lifting, the weight of the load must be assessed as well as centre of gravity to ensure that the truck is capable of lifting.



The forks must be suitably adjusted for the load and placed in the correct position, i.e. fully inserted so that the forks are evenly loaded during lifting.



The mast should not be tilted forwards when a load is being raised or lowered.



When lifting and lowering loads during stacking operations, the handbrake should be on and care should be taken not to dislodge other stacks.



Tandem lifting, where two lift trucks are used to manoeuvre heavy or awkward loads, is a difficult and potentially dangerous operation. It must be supervised by a competent person using recognised signals to guide both of the drivers. The load must be evenly distributed between the trucks and properly secured. The load should not exceed 150% of the capacity of the smaller truck.

Selection of Forklift Truck Selection of suitable equipment is an essential factor in ensuring forklift truck safety. There are many types of truck available for a range of activities, and these were described earlier. Counterbalance trucks are extensively used throughout industry, and there are many situations where specialist trucks such as reach trucks, telescopic materials handlers or rough terrain trucks are required. Many accidents occur due to the incorrect selection and/or use of forklift trucks. The following factors need to be taken into account where selecting forklift trucks: 

Nature of the loads to be transported. This will determine the size, capacity and mast height of the truck.



Operational area, which will determine: the power source (battery indoors, diesel outdoors); type of tyres (solid or pneumatic); protection for operator (overturning or falling objects); or warning systems if pedestrians are nearby.

Capacity Plates and Safe Working Loads The rated capacity of a forklift truck is the maximum weight (kg) at a maximum load centre (m). The load centre is measured from the heel of the forks, e.g. 1000 kg at 0.5 m load centre. Any deviation from the rated capacity will cause instability and/or overloading, and therefore it is essential that this information is displayed on the truck itself.

Driver Training Operator training should include three stages: •

Basic Training

This includes the basic skills and knowledge required for safe operation of the type of lift truck and attachments that the driver will use. This should be training off-the-job. •

Specific Job Training

This stage of training should cover knowledge of the workplace, any special requirements of the work to be undertaken and the use of specific attachments. Again it should be training off-the-job and is often combined or integrated with basic training. The training should include:

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•

−

Controls of the lift truck to be used.

−

Routine inspections of the truck, which should be carried out by the operator.

−

Use of the truck in various locations such as gangways, loading bays, slopes, rough terrain.

−

Problems of working in poor weather.

−

Site rules such as one-way systems.

−

Speed limits.

−

Work near overhead lines and excavations.

−

Work to be undertaken, such as loading particular vehicles.

−

Using working platforms on forks.

Familiarisation Training

This is training on-the-job where the driver operates the truck using the skills learned, under close supervision and under normal working conditions. It can also include training on new machines for existing trained and competent operators. •

Refresher Training

This type of training may be necessary for drivers who have not operated lift trucks for some time, will operate unfamiliar trucks or if there is a change in the area of work. Refresher training on a regular basis is also beneficial for all operators.

Certification A record of each driver who has successfully completed the training should be retained by the employer. The record should indicate the types of lift truck that the employee may operate, and any special conditions such as area limitations and date of authorisation. The employee should be issued with a certificate or copy as evidence of training that can be used in the event of change in employment.

Vehicle Maintenance and Inspections All hoists and lifts must have an examination by a competent person and the results recorded. The frequency of the inspection should be every six months, if used for carrying people (for example, a forklift truck used with an inspection bay) or every 12 months for other lifting equipment. Where faults are found on the equipment, the competent person may have the equipment taken out of use immediately, have the repairs carried out and re-examined before letting the equipment back into use. In terms of inspection and maintenance, the manufacturer and authorised supplier’s instructions should be followed. Operators themselves should not carry out repairs or adjustments to a lift truck unless they are suitably qualified and have been authorised. Where the lift trucks in use are hired, arrangements should be made to ensure proper inspection, maintenance and servicing and, when lift trucks are on long-term hire, users have a duty to make sure that the trucks are safe for their employees to use and are thoroughly examined at appropriate intervals.

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Daily Checks At the start of each shift, the operator should check the lift truck and report any defects that might affect its safe operation to the supervisor, so that such defects can be corrected. Checks should include:  Tyres: −

Tyre pressures should be checked, as incorrectly inflated tyres can affect the stability of the lift truck and its load.

−

Tyres should also be checked for damage, for example, from swarf and nails, as well as for bubbles and tears.



Parking brakes, service brakes and steering gear.



Fuel, water and oil in trucks with internal combustion engines.



Batteries in battery-operated trucks.



Systems for lifting, tilting and manipulation, including attachments. −

Hydraulic systems should be from leaks and hydraulic fluid levels should be correct.



Audible warning signal.



Lights.



Mirrors.

Weekly Checks Weekly checks are appropriate for trucks that are in constant use. Checks should include: 

All daily checks discussed earlier.



An operational check of the steering gear, lifting gear, condition of the battery and other working parts.



The condition of the mast, fork arms, attachments, tyres and any chains and ropes used in the lifting mechanisms, and, if fitted, the operator restraint.



Security of the overhead guard and load backrest extension.

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Title

Page

Electrical Safety

HOW ELECTRICITY CAN CAUSE HARM ............................................................................................................... 3 ELECTRIC SHOCK ................................................................................................................................................... 3 BURNS ................................................................................................................................................................ 5 FIRE .................................................................................................................................................................. 5 ELECTRIC ARCS ..................................................................................................................................................... 6 EXPLOSION .......................................................................................................................................................... 6 SECONDARY EFFECTS OF ELECTRIC SHOCK .................................................................................................................... 6 TYPICAL CAUSES OF ELECTRICAL FAILURES...................................................................................................... 7 DEFECTIVE WIRING ................................................................................................................................................ 7 DAMAGED SOCKETS AND EQUIPMENT ........................................................................................................................... 7 OVERLOADED SOCKETS ............................................................................................................................................ 7 INCORRECT FUSES.................................................................................................................................................. 7 UNSAFE INSTALLATIONS ........................................................................................................................................... 7 IMPROPER USE OF ELECTRICAL INSTALLATIONS AND EQUIPMENT .......................................................................................... 7 CONTROLLING THE RISKS FROM ELECTRICITY ................................................................................................. 9 PROPER INSTALLATION OF WIRING AND FIXED EQUIPMENT................................................................................................. 9 PROTECTION AGAINST ELECTRIC SHOCK, FIRE AND EXPLOSION.......................................................................................... 10 EQUIPMENT FOR USE IN FLAMMABLE OR EXPLOSIVE ATMOSPHERES..................................................................................... 12 IP CODES – PREVENTING INGRESS OF SOLIDS AND LIQUIDS ............................................................................................. 14 INSPECTION, TESTING AND MAINTENANCE OF ELECTRICAL EQUIPMENT ...................................................... 15 MAINTAINING ELECTRICAL EQUIPMENT ....................................................................................................................... 15 PORTABLE APPLIANCE TESTING ................................................................................................................................ 18 FIXED INSTALLATION TESTING ................................................................................................................................. 19


BSC International Diploma | Unit 1 Element 1B: Applied Health and Safety Management Study Unit 1B8 | Electrical Safety Learning Outcomes When you have worked through this Study Unit, you will be able to:

1.B.8.1 Explain how electricity may cause harm 1.B.8.2 Outline the factors contributing to risks from electricity 1.B.8.3 Determine, implement, evaluate and maintain measures for controlling risks from electricity 1.B.8.4 Develop a regime for the inspection, testing and maintenance of electrical equipment

Unit 6:

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How Electricity Can Cause Harm Electric Shock Effects on the Body An electric shock results in a convulsive response by the nervous system to the passage of electricity through part of the body. No voltage can be considered safe in all circumstances, although low voltages may reduce the risk. We must always assume that the electricity supply is potentially fatal. The voltage supply will undoubtedly vary from country to country. Shock accidents usually occur when a person makes a contact with a live conductor when in simultaneous contact with an earthed object; for example, a person touching a live terminal in a fuse-box whilst standing on a concrete floor. The reason for this is that most electrical supply systems are deliberately connected to earth at some point and, by touching one live terminal, the person automatically completes a circuit through his or her body and feet back to the supply system, through the earth. Once an electric current has passed the barrier of the skin, which has a relatively high resistance, the body itself offers little resistance and the current may take one of numerous paths through it. In order to function, the body uses electrochemical impulses through the nervous system. The muscles are controlled by a small current in the order of four microamps acting on the nervous system. In order for us to grasp an object, a signal is sent down the nervous system that causes the muscles to contract. The firmness of the grasping of the hand, for instance, will depend upon the strength of the contraction of the muscles that is in turn dependent upon the strength of the signal reaching them. When an electric shock is received to the hand, the muscles in the arms react to this electric current in a similar way to that in which they react to the current generated in the body. If this current is in excess of about 10 milliamps the contracting muscles overcome the release muscles and involuntary grasping takes place that will continue whilst the electric current is flowing. Because the current swamps the effect of the ordinary control current the hand will, if holding the 'live' source, be unable to let go. The value of current that causes this effect is termed the 'let-go' value. The current may have a number of effects on the body, any of which may prove fatal:

Respiratory failure.

Fibrillation of the heart.

Cardiac arrest.

Muscular contractions.

Internal burns.

Factors Influencing Severity of Effects on the Body The severity and type of injury will depend upon:

Body electrical resistance.

The amount and nature of current passing through the body.

The parts of the body through which the current passes.

The length of time current flows through the body.

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Body Electrical Resistance The human body can be considered as two parallel resistance paths. Externally, the outer skin has a relatively high resistance whilst, internally, the bloodstream and body tissues offer a relatively low resistance. The average dry skin has a resistance of between 1,500 – 2,000 ohms hand to foot, but the resistance drops considerably when the hands are wet. So once a person is holding an electrical source, the situation can only become worse. The person will immediately feel fear and will perspire. The perspiration reduces skin resistance and hence the current increases, which in turn leads to a firmer grasp of the source of electricity. Heating caused by the passage of electricity is proportional to the square of the current, so an increase in the current will cause an increase of the heating at the skin and the skin will burn. The skin will then be destroyed at the point of contact, leading to a further reduction in the resistance and a further increase of current. Amount and Nature of Current Passing through the Body The current passing through the body can be either direct current (DC) or alternating current (AC). The current type will depend on the source of the electric shock. Mains supply in the UK is AC (50 Hertz or 50 cycles per second). Batteries provide a DC supply. Direct current is generally considered more 'hazardous' than AC, because the various ill-health effects of electric shock will be experienced at lower voltages. This is due to the essential nature of DC, which flows in one direction only and does not fluctuate in magnitude. With AC, the current flow oscillates through the conductor and magnitude does fluctuate – there are also zero current flow periods. Current Path: Parts of the Body through which the Current Passes In order for an electric shock to occur, the body must form part of an electrical circuit. There must be a point of entry and a point of departure for the electrical current. Current paths through the heart are the most dangerous and the most likely to cause electrocution. Examples of such pathways would be a shock: from arm to arm, from chest to arm, arm to chest, head to leg and arm to leg. Duration: Length of Time Current Flows through the Body Very low levels of electric current below the perception level can be sustained almost indefinitely. However, a maximum current of, for example, 100 milliamps can only be endured for about one second. In between these two extremes, the let-go value could cause death by asphyxiation if sustained for more than a few minutes. (Please see earlier in these notes for a reminder of the 'let-go' value.) It is not possible to make definite statements to cover all situations, voltages, currents and people. There are many variables that will affect the seriousness of an electric shock to a particular person. For example, the electrical resistance of the skin, which would be low in the case of a child with a soft moist hand, would be high in the case of an adult manual worker with hard dry hands. The actual path of the current through the body is relevant; so is the general state of health of the person. To help illustrate these points, the effects of a shock current passing through the body from hand-held electrodes are shown in the table that follows:

Effects of Electric Shock

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Current in Milliamps 0.5-2 2-10

Effects Threshold of perception Painful sensation

10-25

Inability to let go, danger of asphyxiation

25-80

Loss of consciousness from heart or respiratory failure

Over 80

Burns at point of contact, death from ventricular fibrillation

Burns Direct Electrical burns are caused by the intense heating effect of an electric current as it passes through the body and may result from only a brief passage of electricity. The burns are likely to be most severe at locations along the path of the current where the resistance is greatest. Burns usually occur on the surface of the skin at points of contact but high currents can create internal burns which cause damage to red blood cells and muscle tissue. Such burns are often deep-seated and slow to heal.

Indirect Electric arcing generates large amounts of energy and leads to burns caused by radiation; both infra-red, which produces a sensation of heat, to ultraviolet, which can burn the skin and cause 'arc eye' or 'eye flash', which is an eye irritation. All electrical burns, should receive immediate medical attention.

Fire Common Causes of Fires Fires of electrical origin can be caused in several ways:

Leakage of current due to poor or inadequate electrical insulation, e.g. damaged insulation on flexible cables can lead to leakage of current. This could lead to the ignition of flammable vapour e.g. arcing or sparking electrical equipment located in/adjacent to a paint spray booth may ignite flammable paint vapours produced during the spraying operation.

Overheating of electrical equipment and cables due to overloading of conductors, e.g. flexible cable wound onto cable drums can overheat due to the lower thermal rating of cable that is wound; a safe current/time limit should be specified by the manufacturer.

Overheating of flammable materials too close to electrical equipment, which is otherwise operating normally, e.g. waste paper next to electrical equipment that may have hot surfaces, while in operation.

Mechanical damage, e.g. the use of adaptors into which a number of plugs are connected can lead to mechanical damage to the socket contacts, causing arcing between them and the plug pins which can result in fire.

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All of the above can ignite flammable materials if the temperature attained by the fault is sufficiently high.

Electric Arcs Arcing can occur when the potential difference between conductors is great enough to overcome the resistance of the conductive path between one conductor and another that is at a lower potential. The resulting arc will be capable of crossing the air gap or insulation that separates the two conductors. Very large amounts of energy can be created in a short time, usually less than one second. Arcing generates ultraviolet radiation that can burn the skin and the eye. This phenomenon is exactly the same as the 'arc eye' that a welder might experience if they used an arc welder without adequate eye protection. The surface layers of the eye are burned by the intense radiation, leading to severe pain and temporary blindness. Additional burns may result from radiated heat and from molten/hot metal fragments. Severe, sometimes fatal, injuries and burns or serious fires may result from an arcing incident. If the voltages are high enough, X-Ray radiation may also be generated, with obvious health consequences.

Explosion Explosions, which can cause burns and injuries from flying debris, can arise in two ways:

Ignition of a flammable substance such as a gas, dust, liquid or vapour by an electric arc, spark or the heating effect of electrical equipment that has a hot surface. There is no voltage limit that will allow the safe use of electricity in a potentially flammable environment without additional precautions being taken. For example, an explosion could result if inappropriate electrical equipment is used in a workroom where significant concentrations of airborne dust occur.

The explosion of equipment due to excessive currents or prolonged internal arcing faults. The overload of energy can cause rapid and violent rupture of the equipment. For example, an electrical multimeter (test meter) might explode if its probes are touched onto electrical components where very high potential difference (voltage) exists. Large current flows, the meter explodes and the worker is engulfed in a fireball of molten metal and burning plastic.

Secondary Effects of Electric Shock Electric shock may also initiate secondary causes of injury. The involuntary muscular reaction may throw the arm back so violently that the muscles become overstrained or ligaments are torn. More often, however, the shock startles the victim and causes momentary loss of control and balance, resulting in falls. If working from a ladder the fall can result in more serious injuries than the electric shock.

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Typical Causes of Electrical Failures Defective Wiring Electrical wiring should be of adequate capacity to carry the intended current, properly insulated and free of badly made joints. Excess current from incorrectly sized cables can cause overheating and represent a fire hazard, and damaged insulation increases the risk of contact with live conductors, as does insecure joints.

Damaged Sockets and Equipment Damaged sockets and electrical equipment may allow access to live conductors that should be protected by the integrity of the casing. They may also provide inadequate electrical contact and lead to overheating.

Overloaded Sockets All electrical equipment and circuits are rated to carry a given safe current which will keep the temperature rise of the conductors in the circuit or appliance within safe limits. Overloading of electrical sockets beyond the rating of the circuit can cause overheating which in turn can lead to fire. The use of multi sockets is a common cause for concern in relation to overloading and can be easily overcome by installing sufficient numbers of fixed socket points to cope with the demands of the workplace appliances.

Incorrect Fuses Fuses are designed to melt at a temperature that is related to the excess current against which protection is required. So, for example, a 5-amp fuse will melt if the current flow exceeds five amps, thus protecting the circuit from excess current. The primary purpose of the fuse is to prevent significant excess current flowing through the circuit for a long enough period of time to cause overheating, fire and explosion. Fuses do not react quickly enough to prevent electric shock and, in most instances, are not sensitive enough to give electric shock protection. Bear in mind that a fault current of 80 milliamps flowing through a person can cause heart fibrillation, but is well below the current necessary to blow a 5-amp fuse. In the event of an electrical fault with a piece if equipment – for example, a small earth leakage due to short circuit – the fuse protecting the equipment may blow. The operator (or repairer) may then be tempted to replace the fuse with one of higher rating in the hope that this will allow the continued operation of the equipment with a 'minor' fault. This can, of course, be a dangerous course of action with increased risk of overheating, fire or explosion. In extreme examples, equipment has been found with the fuses removed and replaced with 'alternatives' – pieces of metal, wire, tinfoil, etc.

Unsafe Installations Electrical installations must meet any applicable standards and be installed by competent and certified persons. Installations failing to meet these standards are likely to represent a significant risk to any persons using such premises or equipment.

Improper Use of Electrical Installations and Equipment Many reportable electrical accidents involve portable equipment. The likelihood of accidents occurring, as well as the severity of such accidents, will vary depending on:

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The type of electrical equipment.

The way in which it is used.

The environment in which it is used.

A high-risk situation arises, for example, where a pressure water cleaner is used outside, with the cable trailing on the ground, where it can be damaged by vehicles and other equipment, and where water is present. Damage to the cable or other parts is likely to result in the operator or others receiving an electric shock. Similar risks result when other electrical equipment, such as drills and portable grinders, are used in a harsh and sometimes wet environment, such as at a construction site, where there is a high probability of mechanical damage. Lower risks result from floor cleaners or kettles, which are generally used in a less hazardous environment, e.g. offices and hotels, but can be subject to intensive use and wear. This can eventually lead to faults that can also result in shock, burns or a fire. Other conditions that may lead to accidents include:

Incorrectly made connections.

Damaged or missing insulation, exposing live conductors.

Insulation failure, resulting in leakage currents and live metalwork.

Servicing equipment without disconnecting supply.

Misuse of equipment.

'Unauthorised' equipment brought into the work environment by employees, e.g. electric heaters, kettles, coffee percolators, electric fans, etc.

Portable electric tools and equipment account for a large proportion of the electrical accidents that occur each year. Most accidents are electric shock incidents, but many result in burns from arcing or fire. Accidents are typically caused by:

The use of unsuitable equipment, e.g. flexible cable being dragged through areas where oils, greases or solvents are present. In this case, a cable should be selected which has a sheath resistant to those chemicals.

The use of defective equipment, e.g. badly made joints in flexible cables that can expose bare live conductors. Operators should be instructed never to make their own repairs, never to use defective equipment, and to withdraw such equipment from use and not reuse it until it has been repaired and checked by a competent person.

The misuse of equipment, e.g. attempting to service equipment without disconnecting it from the electricity supply, rather than withdrawing it from service for inspection by a competent person.

Inadequate maintenance, e.g. no system of regular inspection and, if necessary, testing and repair of equipment. Regular inspections of portable equipment are particularly important because of the hard use that such equipment often suffers.

The hazards associated with hand-held tools are particularly significant as the hand is likely to be gripping the tool when in operation, making it more difficult or impossible for the operator to let go in the event of a fault.

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Controlling the Risks from Electricity The prime objective of electrical safety is to protect people from electric shock, and also from fire and burns, arising from contact with electricity. The following section provides an overview of the main considerations for achieving this objective.

Proper Installation of Wiring and Fixed Equipment Hard-wired electrical systems including main supply to buildings, distribution systems and fixed plant require very careful planning and installation to avoid potential for failure. Correct electrical installation (comprising such items as cables, conduit or other mechanical protection, main and local switches, distribution boards, fuses, socket outlets etc) is vital as failure to introduce the necessary protection systems or incorrectly installing the system may lead to overheating causing fire or to systems becoming “live” leading to electrocution. Planning requires an understanding of required loads, legal requirements and distribution requirements. In the UK requirements for Electrical Installations are set out in the 17th edition of the Institution of Electrical Engineers Wiring Regulations (British Standard 7671). These Regulations are non-statutory, but they form a code of practice that is widely recognised and accepted as best practice in relation to the design, installation and maintenance of fixed electrical installations. The Regulations: 

Set safety standards for designers, installers, erectors and testers of permanent and temporary electrical installations.



Aim to protect people and livestock from the hazards of electric shock, burns, fires and the mechanical movement of electrically powered machinery.



Apply only to installations operating up to 1,000 volts ac.

All electricians in the UK are aware of these requirements. For many years, they have provided the rules that must be followed to make sure that electrical installations are safe. The details of the IEE Regulations are too complex to deal with here, but the Regulations include specifications for: 

Installation requirements and characteristics.



Installation control and protection:



Cables, conduits and trunking:



Earthing:



Circuits:



Inspection and testing:



Test instruments.

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Protection against Electric Shock, Fire and Explosion Segregation One method of providing protection against electric shock, fire and explosion is through the segregation of electrical hazards from those likely to come into contact with them. For example, electricity pylons have barbed wire and/or fences to prevent persons from reaching the electricity conductors.

Isolation and Switching Off There is a difference between isolation and switching off:

Switching off refers to depriving the equipment of electric power, but leaving it still connected.

Isolation refers to physically separating it from any source of electric power, with the additional step being taken of ensuring that it cannot be inadvertently re-energised.

Isolation should establish an effective barrier between the equipment and the supply and ensure that no unauthorised person is able to remove the barrier. In particular, it should:

Establish an air gap between the contacts in the switch or some other barrier that would prevent the flow of current under all conditions of use.

Include a device such as a padlock or lock that will prevent the removal of the barrier by unauthorised persons.

Be accessible, easy to operate and clearly labelled.

Earthing By earthing the exposed metal parts that should not normally carry a current, any fault current is provided with a low impedance path to earth should it become live. If all exposed metalwork is properly bonded to earth, it cannot be made live by a fault and the risk of shock is eliminated. The integrity of the earth conductor is vital because if it fails, the protection is removed. Earthing measures should be connected such that the fault current will operate protective devices such as fuses and residual current devices, so cutting off the supply by breaking the circuit. In certain cases, such as wet environments, additional protection is necessary due to the hazard posed by the close proximity of water, electricity and metal objects – for example, in a central heating system driven by an electric pump. All extraneous metalwork should be connected by a common bonding conductor that ensures that all the metalwork is at the same potential. This measure is called equipotential bonding. A current will not flow between two points at the same potential so, if any of the metal fittings become live, any of the other metal fittings may be touched simultaneously without the risk of electric shock. A common connection to earth is usually made.

Reduced Voltage These are also known as low voltages. Where environmental conditions are harsh, such as on construction sites or in areas that are wet, the use of reduced or low voltages is advisable to reduce shock effect. For hand-held portable tools and the smaller transportable units, the 110volt centre-tapped (CTE) system is recommended. The system relies on the mid-point of the reduced voltage (i.e. 110 volts or less) transformer to be earthed. The maximum shock voltage to earth is half the supply voltage, i.e. 55 volts in the event of direct contact. As most

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shocks occur between a live part and earth this is a major step in the reduction of the shock effect. The full 110-volt supply is available to power the equipment. Lower voltage systems, which are called "safety extra low voltage" or SELV, are those in which the voltage does not exceed 50 volts ac between conductors in a circuit that is isolated from the supply mains, and from earth, by means such as a safety-isolating transformer. These systems represent even less of a hazard and should be used in other environments such as vehicle washing areas and in the vicinity of swimming pools. They are also recommended for hand lamps, soldering irons and other small hand tools where the risk of shock is high. For work in confined spaces, extra-low voltage equipment of less than 25 volts will be needed. Portable hand lamps for use in confined spaces and damp conditions should also be less than 25 volts. Battery operated power tools should also be less than 25 volts, and these could be a good alternative to use in confined spaces as they have a reduced risk of fire, electric shock and explosion.

Double Insulation If equipment has a metal enclosure, precautions must be taken to prevent the metalwork from becoming live. This can be achieved by 'double-insulation' in which the live parts of the equipment are covered by two layers of insulating material. Each layer is capable of adequately insulating the live parts alone, but together they ensure that the occurrence of insulation failure and its associated danger is extremely improbable. This method is also suitable for portable equipment that often suffers particularly rough use, but regular maintenance is essential, as the insulation only remains effective while it is intact. In addition to maintenance, the insulation must be soundly constructed and the equipment properly used.

RCCB, ELCB, RCD Residual Current Circuit Breakers (RCCBS), current-operated Earth Leakage Circuit Breakers (ELCBs) and Residual Current Devices (RCDs) are different names for the same device. They continually measure the current flowing in the live and neutral lines, and trip the circuit if there is any difference caused by short circuit to earth. They usually trip within 30 milliseconds if a fault current of 30 mA is detected. Consequently, human contact with a live conductor resulting in electrical current flow to earth will be detected fast enough to prevent sufficient current flow for long enough to prevent fatal shock. As with circuit breakers, these devices require regular testing to ensure that they continue to work correctly. These devices are sensitive enough to detect a leakage current too small to operate a fuse, but which may be large enough to start a fire. Such a current would be detected by the device that trips the supply circuit breaker. Every RCD has a test button that should be regularly checked to ensure correct operation.

Fusing A fuse forms a weak link in a circuit by overheating and melting by design if the current exceeds the safe limit. A circuit breaker is a mechanical device in the form of a switch that automatically opens if the circuit is overloaded. Both protective devices should be chosen so that their rating is above the operating current required by the equipment but less than the current rating of the cable in the circuit.

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Training When people are engaged in work activities where technical knowledge or experience is necessary to prevent danger or injury, they must possess either of these skills, or be under appropriate supervision. The scope of technical knowledge or experience may include:

Adequate knowledge of electricity.

Adequate experience of electrical work.

Adequate understanding of the system to be worked on, and practical experience of that class of system.

Understanding of the hazards that may arise during the work and the precautions that must be taken.

Ability to recognise at all times whether it is safe to continue working.

A person responsible for isolating equipment before work commences on it must possess adequate technical knowledge or experience to prevent danger, and ensure the safety of the persons working on the equipment. If the isolation has been carried out correctly, danger will be prevented for the duration of the work. In the case of work on live equipment, a risk of injury exists and therefore danger is present. In these circumstances, knowledge or experience must be such that injury is prevented. It is vital that both employers and employees share a responsibility for safety:

The employer should ensure that his workers receive appropriate training and instruction so that they understand the safe procedures that are relevant to their work, and/or they are adequately supervised.

All employees should comply with the instructions or rules set down by their employers to ensure that work is carried out safely.

Equipment for use in Flammable or Explosive Atmospheres It is essential that electrical equipment used in the flammable atmospheres is of the correct type. The equipment must be constructed to the appropriate standard, tested and certified by the national testing authority. Although other countries may vary, in the UK this authority is the British Approvals Service for Electrical Equipment in Flammable Atmospheres (BASEEFA). The categories of equipment are outlined in the following table: Explosion-Protected Equipment: Symbol Meanings Symbol

Meaning

Eex and Ex

explosion-protected

i

intrinsically safe

p

pressurised

s

special protection

d

flameproof

e

increased safety

N or n

non-sparking

o

oil-immersed

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•

q

powder-filled

m

encapsulated

Intrinsically Safe - i This design ensures that the energy level is insufficient to produce an incendiary spark. Two categories of intrinsically safe equipment exist: 'ia' which is more stringent as it allows for two simultaneous faults, and 'ib' which allows for only one. Only ia equipment can be used (exceptionally) in Zone 0 if sparking contacts are not part of the equipment. Examples of type i are detecting and measuring instruments.

•

Pressurised - p Pressurised equipment excludes flammable gas from the equipment by achieving a higher pressure inside the equipment than is present in its surroundings. Pressurisation can be achieved by drawing clean air from a safe area or an inert gas into the equipment under positive pressure. The air leaks out from small gaps in the casing of the equipment thereby preventing the ingress of gas/vapour from the flammable atmosphere. The pressurising equipment must be monitored and interlocked to the supply in order to disconnect it should the air supply fail or if the pressure drops. Type p protection is applicable to almost all types of equipment and systems. (Purging, as opposed to pressurising, is a method whereby a flow of air or inert gas is maintained in a room or enclosure to reduce or prevent a flammable atmosphere occurring.)

•

Special Protection - s This is a special category of equipment, not included in the other categories, for which there is no EH standard. It usually applies to individual components within the equipment. Examples of type s equipment are catalytic gas detectors and lightweight fluorescent hand lamps.

•

Flameproof - d This equipment is totally enclosed and the casing must be robust enough to withstand internal explosions without igniting the flammable atmosphere in which the equipment is located. Examples of type d equipment are motors, lighting, switchgear and portable hand lamps.

•

Increased Safety - e This equipment does not arc, spark or generate temperatures high enough to ignite a flammable atmosphere. Examples of type e equipment are induction motors and certain types of luminaires. Type e equipment may be used in Zone 1 areas.

•

Non-Sparking - N or n Less stringent requirements have to be met by this category as compared with type e equipment above. It is intended for use in Zone 2 applications. Examples of type n or N equipment are some luminaires and solid-state relays.

•

Oil-Immersed - o Such equipment has all parts that are likely to arc under normal conditions immersed in oil to prevent ignition of a flammable atmosphere that may exist above the surface of the oil. All other parts are also protected by oil or by some other approved method.

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Powder-Filled - q

•

All live parts are covered by powder such as quartz or silica, the principle being similar to oil-immersed equipment. Encapsulated - m

•

This equipment is embedded in an insulating compound that excludes the flammable atmosphere.

IP Codes – Preventing ingress of Solids and Liquids The International Electrotechnical Commission publishes a widely accepted standard (IEC 60529) that defines a classification system for the effectiveness of enclosures in preventing the ingress of solids and liquids. The system uses two letters, IP (for Ingress Protection), followed by two digits. The first digit is for solids; the second is for liquids. The table that follows explains the classification. For example: IP 65 = a dust tight case able to withstand a water jet and is a common level of protection for outdoor equipment. IP Codes for Protection against Ingress of Solids and Liquids Digit Value

st

nd

1 Digit (Solids)

2

0

No protection

No protection

1

Protected against objects > 50 mm

Protected against dripping water

2

Protected against objects > 12 mm

Protected against dripping water when tilted ± 15°

3

Protected against objects > 2.5 mm

Protected against spraying water

4

Protected against objects > 1.0 mm

Protected against splashing water

5

Dust protected

Protected against water jets

6

Dust tight

Protected against heavy seas

7

Not used

Protected against immersion to > 150 mm

8

Not used

Protected against submersion to > 1m

X

Not solid rated

Not liquid rated

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Digit (Liquids)

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Inspection, Testing and Maintenance of Electrical Equipment Maintaining Electrical Equipment Maintenance is a general term that in practice can include visual inspection, testing, repair and replacement. Maintenance will determine whether equipment is fully serviceable or remedial action is necessary. Routine inspection and appropriate testing where necessary, are normally part of any overall strategy for ensuring that work equipment is maintained in a safe condition. The following discussion is based on the guidance given in an HSE publication - HSG107, Maintaining Portable and Transportable Electrical Equipment. The principles discussed apply equally to fixed electrical equipment. Cost-effective maintenance of equipment can be achieved by a combination of actions applied at three levels:

Checks by the user.

Visual inspections by a person appointed to do so.

Combined inspection and tests by a competent person or by a contractor.

This should be followed up by management monitoring the effectiveness of the system, and action should be taken where faults are found, particularly where detected fault levels or types of faults are found repeatedly.

User Checks As with portable electrical equipment, the person utilising the electrical equipment should be encouraged to look critically at it and, after a minimum basic training, visually check for signs that the equipment is not in sound condition, for example:

There is damage (apart from light scuffing) to the cable sheath.

The plug is damaged; for example, the casing is cracked or the pins are bent.

There are inadequate joints, including taped joints in the cable.

The outer sheath of the cable is not effectively secured where it enters the plug or the equipment; obvious evidence would be if the coloured insulation of the internal cable cores were showing.

The equipment has been subjected to conditions for which it is not suitable, e.g. it is wet or excessively contaminated.

There is damage to the external casing of the equipment or there are some loose parts or screws.

These checks also apply to extension leads and associated plugs and sockets. Checks should be undertaken by the user before and during use. Any faults should be reported to management and the equipment taken out of use immediately. Management should take effective steps to ensure that the equipment is not used again until repaired by a person competent to carry out the task (e.g. the defective equipment could be labelled as 'faulty' and its associated plug removed).

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Formal Visual Inspections The most important component of a maintenance regime is usually the formal visual inspection carried out routinely by a competent person. Most potentially dangerous faults can be picked up by such inspections. To control the risks and to monitor the user checks, a competent person should carry out regular inspections that include visual checks similar to those discussed above but undertaken in a more formal and systematic manner. Additional checks could include removing the plug cover and checking that a fuse is being used (e.g. it is a fuse, not a piece of wire, a nail, etc.), the cord grip is effective, the cable terminations are secure and correct, including an earth where appropriate, and there is no sign of internal damage, overheating or ingress of liquid or foreign matter. The formal visual inspection should not include taking the equipment apart. This should be confined, where necessary, to the combined inspection and testing, discussed later. The competent person can normally be a member of staff who has sufficient information and knowledge, following appropriate training on what to look for and what is acceptable, and who has been given the task of carrying out the inspection. To avoid danger, competent persons should know when the limit of their knowledge and experience has been reached (this is one of the definitions of a competent person). Simple written guidance relating to the visual inspection can be produced, summarising what to look for, procedures to follow when faults are found and when unauthorised equipment is found in use. It can aid whoever is carrying out the formal visual inspection, as well as users. The inspections should be carried out at regular intervals. The period between inspections can vary considerably depending on the type of equipment, the conditions of use and the environment. For example, equipment used on a construction site or in a heavy steel fabrication workshop will need much more frequent inspection than equipment such as floor cleaners in an office. In all cases, however, the period between inspections should be reviewed in the light of experience. Faulty equipment should be taken out of service and not used again until properly repaired. In order to take remedial action, management can use the pattern of faults to show:

The right equipment is being selected for the job.

Further protection may be necessary in a harsh environment.

The equipment is being misused.

Combined Inspection and Tests The checks and inspections outlined above will, if carried out properly, reveal most (but not all) potentially dangerous faults. However, some deterioration of the cable, its terminals and the equipment itself can be expected after significant use. Additionally, equipment may be misused or abused to the extent that it may give rise to danger. Testing, together with a thorough visual inspection, can detect faults such as loss of earth integrity, e.g. broken earth wire within a flexible cable, or deterioration of insulation integrity or contamination of internal and external surfaces. Failure of insulation could result in the user receiving an electric shock with potentially fatal results. Periodic inspection and testing are the only reliable ways of detecting such faults, and should be carried out to back up the inspection regime. Occasions when testing is likely to be justified are:

Whenever there is reason to suppose the equipment may be defective and this cannot be confirmed by visual inspection.

After any repair, modification or similar work.

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At periods appropriate to the equipment, the manner and frequency of use, and the environment.

The inspection carried out in conjunction with the testing should usually include checks for:

Correct fusing.

Effective termination of cables and cores.

Suitability of the equipment for its environment.

Combined inspection and testing should be carried out by someone with a higher level of competence than that required for inspection alone, because the results of the tests may call for interpretation and appropriate electrical knowledge will be essential. However, this can often be carried out by a competent employee. Persons testing portable electrical equipment should be fully trained. It is the employer's responsibility to ensure they are competent for the work they undertake.

Records of Maintenance and Tests There are many benefits of recording maintenance, including test results. A suitable log is useful as a management tool for monitoring and reviewing the effectiveness of the maintenance scheme and indeed to demonstrate that a scheme exists. It can also be used as an inventory of portable electrical equipment and a check on the use of unauthorised equipment (e.g. domestic kettles or electric heaters brought to work by employees). The log can include faults found during inspection and may give a useful indication of the types of equipment or environment which are subject to a higher than average level of wear or damage. This will help monitor whether suitable equipment has been selected. Entries in a test log can also highlight any adverse trends in test readings that may affect the safety of the equipment, thus enabling remedial action to be taken. Care should be taken in interpreting trends where a subsequent test may be carried out with a different instrument from that used for an earlier test, since differences in the results may be due to differences in the test instruments rather than indicating deterioration in the equipment being tested. Records do not necessarily have to be on a paper system since test instruments are available which store the data electronically for downloading directly onto a computer database. It is useful to label equipment to indicate that it has been tested satisfactorily, i.e. has been passed as safe, and when the date for the next test is due. Otherwise, individual items may be missed on consecutive occasions.

Frequency of Inspection and Testing Deciding on the frequency of maintenance is a matter of judgment for those responsible for the equipment, and should be based on an assessment of risk. It can be undertaken as part of the assessment of risks. Factors to consider when making the assessment include:

Type of equipment and whether or not it is hand-held.

Manufacturer's recommendations.

Initial integrity and soundness of the equipment.

Age of the equipment.

Working environment in which the equipment is used (e.g. wet or dusty) or likelihood of mechanical damage.

Frequency of use and the duty cycle of the equipment.

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Foreseeable abuse of the equipment.

Effects of any modifications or repairs to the equipment.

Analysis of previous records of maintenance, including both formal inspection and combined inspection and testing.

Portable Appliance Testing To prevent accidents, routine inspection and maintenance of portable equipment is essential. All pieces of equipment should be identified by a serial number and recorded in a register which specifies when each item should be recalled for inspection. A nominated person should be appointed to ensure that recall and inspection do take place. The equipment should be marked to indicate to the user when the inspection is due. The frequency of inspection should be determined by the type of equipment and its use, the manufacturers' recommendations, and the experience of the user. The inspection and any subsequent tests and repairs should be carried out by a competent person experienced in this type of work. A record of inspection should be made and kept for the life of the equipment. In addition to regular inspections, operators should be instructed never to use damaged or defective equipment. They should check equipment visually before use and withdraw any defective items from service until repaired. The use of 'unauthorised' equipment in the workplace should be discouraged. Equipment should be inspected for:

Damage, e.g. cuts, abrasion (apart from light scuffing) to the cable covering.

Damage to the plug, e.g. the casing is cracked or the pins are bent.

Non-standard joints, including taped joints in the cable.

The outer covering (sheath) of the cable not being gripped where it enters the plug or the equipment. Look to see if the coloured insulation of the internal wires is showing.

Use in conditions where it is not suitable, e.g. a wet or dusty workplace.

Damage to the outer cover of the equipment or obvious loose parts or screws.

Overheating (burn marks or staining).

In addition, inspection could include removal of the plug cover and checking that:

A fuse is being used (i.e. it is a proper fuse, not a piece of wire, a nail, etc.).

The cord grip is holding the outer part (sheath) of the cable tightly.

The wires, including the earth where fitted, are attached to the correct terminals.

No bare wire is visible other than at the terminals.

The terminal screws are tight.

There is no sign of internal damage, overheating or entry of liquid, dust or dirt.

This does not apply to moulded plugs where only the fuse can be checked. All these checks also apply to extension leads and their plugs.

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Fixed Installation Testing Fixed electrical installations must also be examined and tested at frequent intervals. This will often involve checking that all connections are properly made and that the integrity of the wiring and distribution systems have not been compromised. Thermal imaging is often used to identify any faults in electrical system components which will show up any “hot-spots” that indicates a possible loose connection that is generating heat. The table that follows shows some suggested frequencies for fixed installation testing and inspection: Suggested Testing Intervals Type of Installation

Maximum Period between Inspections

General: Domestic

10 years

Commercial

5 years

Educational establishments

5 years

Hospitals

5 years

Industrial

3 years

Buildings open to the public: Cinemas

1 year

Churches, under 5 years old

2 years

Churches, over 5 years old

1 year

Leisure complexes

1 year

Places of public entertainment

1 year

Restaurants and hotels

1 year

Theatres

1 year

External installations: Agricultural and horticultural

3 years

Caravans

3 years

Caravan sites

1 year

Highway power supplies

6 years

Special installations: Emergency lighting

3 years

Fire alarms

1 year

Launderettes

1 year

Petrol filling stations

1 year

Temporary installations

3 months

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Title

Page

Pressure Systems

WHAT IS A PRESSURE SYSTEM? ......................................................................................................................... 3 HOW PRESSURE SYSTEMS CAN CAUSE HARM .................................................................................................... 4 MAIN HAZARDS ..................................................................................................................................................... 4 CAUSES OF FAILURE ................................................................................................................................................ 4 CONTROLLING RISKS FROM PRESSURE SYSTEMS ............................................................................................. 7 SYSTEMS DESIGN AND INSTALLATION ........................................................................................................................... 7 MAINTENANCE AND INSPECTION ................................................................................................................................. 7 TESTING AND EXAMINATION ...................................................................................................................................... 7 MAINTAINING OPERATING LIMITS ............................................................................................................................... 8 ENVIRONMENTAL CONDITIONS ................................................................................................................................... 8 INSPECTION, TESTING AND MAINTENANCE OF PRESSURE SYSTEMS ............................................................... 9 INITIAL INSPECTION AND CONDITION TESTING ............................................................................................................... 9 INSPECTION REPORTS ........................................................................................................................................... 10 MAINTENANCE OF PRESSURE SYSTEMS ....................................................................................................................... 11 RECORD KEEPING................................................................................................................................................. 12


BSC Awards International Diploma | Unit 1 Element 1B: Applied Health and Safety Management Study Unit 1B9 | Pressure Systems Learning Outcomes When you have worked through this Study Unit, you will be able to:

1.B.9.1 Explain what is meant by a pressure system 1.B.9.2 Explain how pressure systems can cause harm 1.B.9.3 Outline the factors contributing to the risk of pressure system failure 1.B.9.4 Determine, implement, evaluate and maintain measures for controlling risks from pressure systems 1.B.9.5 Develop a regime for the inspection, testing and maintenance of pressure systems

Unit 7:

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What is a Pressure System? Pressure systems are pressure vessels and associated pipe work and protective devices which contains a relevant fluid. A relevant fluid is any liquid or gas contained under pressure. This includes:

Steam;

Any fluid or mixture of fluids which is at a greater pressure than 0.5 bar above atmospheric

Examples of pressure vessels include

boilers and steam heating systems;

pressurised process plant and piping;

compressed air systems (fixed and portable);

pressure cookers, autoclaves and retorts;

heat exchangers and refrigeration plant;

valves, steam traps and filters;

pipework and hoses; and

pressure gauges and level indicators.

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How Pressure Systems Can Cause Harm Hazards that the safety practitioner should be aware of stem from the use or misuse of this energy and from the possible failure of the system

Main Hazards The main hazards associated with Pressure Systems are:

impact from the blast of an explosion or release of compressed liquid or gas;

impact from parts of equipment that fail or any flying debris;

contact with the released liquid or gas, such as steam; and

fire resulting from the escape of flammable liquids or gases.

Catastrophic Failure Catastrophic failure of the pressure vessel or associated pipework can lead to:

Explosions from the sudden release of pressure and consequential blast wave, which can cause considerable harm to persons in the vicinity. Explosions could also cause structural damage, or start a chain leading to further increased damage.

Fire starting where the fluid that has escaped is flammable. Boiling Liquid Expanding Vapour Explosions (BLEVEs) is one example of this, where a sudden release of vapour containing liquid droplets occurs, owing to the failure of a storage vessel. The initial explosion may generate a blast wave, missiles or a fire, or may form a vapour cloud that then gives rise to a secondary explosion and fireball. Significant damage to equipment and buildings from radiant heat is possible from a BLEVE.

Impact with flying debris produced when vessels or pipework fail. Using the example of a BLEVE above, failure of a propane sphere of a diameter of 15 m could cause fragmentation damage extending to about 1,000 m. Severe damage from fragmentation can be expected in the area where 50 per cent or more of the fragments may fall (typically about 100 m from the vessel).

Causes of Failure Excessive Stress When a system is installed and pressured up for the first time, the various parts will move slightly and 'settle in'. If this movement is prevented by, for instance, pipe work being tightly clamped in place, the system will become stressed and this could lead to failure. Residual stresses from manufacturing produce the same effect, and it is difficult when investigating failure to determine which of the two has caused the failure.

Abnormal External Loading 'Abnormal external loading' comes about when external forces are applied to the system, for example, a ladder being rested against pipework.

Overpressure 'Overpressure' occurs when the force making the pressure, for example, flame for boiler or pump, fails to stop when the system pressure is reached.

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Overheating Overheating occurs when the system runs faster than designed and the pressure relief system fails to work, for example, an oil-burning boiler runs at full pressure due to failure of the thermostatic controls. Explosion would occur if the safety valve fails to function. Boilers may suffer this if they have low water levels.

Mechanical Fatigue and Shock This is caused by the physical movement of parts of the system, so setting up fatigue failure. An example of this is the bellows failure at Flixborough, in that the bellows eventually could not withstand the movement. Such movement may be caused by the effects of the movement of the fluid, particularly if it flows in 'pulses', for example, as a result of a water hammer. Shock failure is similar to that of external loading but applied very rapidly.

Thermal Fatigue and Shock This is caused by the constant changes in temperature from hot to cold, and vice versa. These changes have the effect of making the material expand and contract, so setting up cyclic stress reversal leading to fatigue failure.

Brittle Fracture Brittle fracture is caused by cold changing the characteristics of the material from which the system is made. For example, polymer seals need to be selected with care as their use in 'cold' systems makes the material brittle and liable to failure.

Creep Within the elastic limits of a material, stress is proportional to strain. When, however, a material is put under stress near to its elastic limit, it undergoes a process of plastic deformation, referred to as 'creep'. The extent to which creep acts is dependent upon two main factors, time and temperature: 'time' as creep is a slow process, and 'temperature' as creep can be accelerated by increasing the temperatures. Creep has been known to lead to the rupture of pressure systems, for example, through fractured steam pipes. It is primarily controlled by design, in the shape of the components and the choice of materials, for example, chrome-molybdenum steels have low creep characteristics.

Hydrogen Attack 'Hydrogen attack' is a particular problem within steam boilers. The heat and temperature lead to some of the water molecules breaking down into hydrogen and oxygen. The hydrogen atoms, being positively charged and small, move out of the solution and into the material of the pressure system. This affects the properties of the material, generally by weakening it, so that failure becomes more possible.

Corrosive Failure This is caused by substances in the relevant fluid attacking the material from which the system is made. This is usually because of impurities within the fluid, as the system has to be designed to take the fluid. Boilers or other systems using water are particularly susceptible, particularly where the system supply has to be regularly replenished. Corrosive failure will often occur inside the system, making detection difficult, so the examination process must set up a means of detection.

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Leaks Leaks from the pressurised system may result in contact with the fluid that was contained. High-pressure steam will cause scalds and burns. However, the system may contain other substances, including those that could be hazardous to health on contact, such as toxics or corrosives.

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Controlling Risks from Pressure Systems Systems Design and Installation Designers and manufacturers must consider at the manufacturing stage both the purpose of the plant and the means of ensuring compliance with the local regulations. The designer, manufacturer, importer or supplier should consider and take due account of the following, where applicable:

The expected working life (the design life) of the system.

The properties of the contained fluid.

All extreme operating conditions including start-up, shutdown and reasonably foreseeable fault or emergency conditions.

The need for system examination to ensure continued integrity throughout its design life.

Any foreseeable changes to the design conditions.

Conditions for standby operation.

Protection against system failure, using suitable measuring, control and protective devices as appropriate.

Suitable materials for each component part.

The external forces expected to be exerted on the system including thermal loads and wind loading.

Safe access for operation, maintenance and examination, including the fitting of access (e.g. door) safety devices or suitable guards, as appropriate.

Maintenance and Inspection When designing any modifications (including extensions or additions) or repairs to the pressurised parts of the system, whether temporary or permanent, the following should be taken into account:

The original design specification.

The duty for which the system is to be used after the repair or modification, including any change in relevant fluid.

The effects any such work may have on the integrity of the pressure system.

Whether the protective devices are still adequate.

Continued suitability of the written scheme of examination.

Testing and Examination A written scheme of examination should be drawn up and examined in accordance with the scheme. Examination includes testing techniques where appropriate to assess the condition of the system. It is essential that any testing techniques do not introduce additional stresses or other detrimental factors that could increase the risk of pressure system failure. Consequently, non-destructive testing is frequently used. The most widely used techniques are: visual, liquid penetrant, magnetic particle, radiography and ultrasonic tests.

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Maintaining Operating Limits Safe operating limits are the upper limits of pressure and temperature at which the plant was designed to be operated. The upper limit of pressure will be the maximum permissible working pressure on the most recent examination report, or the manufacturer's safe working pressure, as stated in the manufacturer's manual, instruction sheet, or on the maker's plate for the plant itself. By definition, these are the critical safety parameters at which the pressure system must be operated, and any deviation from them will increase the risk of failure.

Environmental Conditions We discussed a range of causes of failure earlier in this chapter. An understanding of the possible failure modes will assist the employer with developing control strategies which will help to reduce the risks of failure.

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Inspection, Testing and Maintenance of Pressure Systems Before a pressure system is operated, the user or owner must ensure that a written scheme of examination has been prepared. It should be drawn up by a competent person, or be drawn up by someone other than a competent person, who is certified as suitable by a competent person. The term 'competent person' is used in connection with two distinct functions:

Drawing up or certifying schemes of examination.

Carrying out examinations under the scheme.

The competent person can be from within the user or owner's organisation or from outside, and should have sufficient understanding of the systems in question to enable that person to draw up schemes of examination or certify them as suitable. The responsibilities may be summarised as follows:

The user or owner ensures the scope of the scheme is appropriate, that is, which parts of the system are covered (with advice, if necessary, from a suitably experienced advisor).

The competent person specifies the nature and frequency of examinations and any special measures necessary to prepare the system for safe examination.

Initial Inspection and Condition Testing A typical inspection and condition testing programme for a low-pressure steam boiler is set out below:

Daily A programme for daily inspections:

Observe operating pressure.

Observe water level.

Observe general conditions.

Determine cause of unusual noises or conditions and correct.

Test water column or gauge glass.

Test water condition and perform corrections as necessary (add chemicals, blow down, etc.).

Record in log.

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Weekly A programme for weekly inspections:

Test low-water fuel cut-off.

Blow down boiler.

Observe condition of flame.

Check oil supply.

Observe operation of condensate or vacuum pump.

Monthly A programme for monthly inspections:

Safety valve-lift lever.

Test flame-detection devices.

Test limit controls.

Test operating controls.

Sludge blow down (if required).

Check condition of heating surfaces for oil pre-heaters.

Check combustion air supply to boiler room.

Annually A programme for annual inspections:

Inspect internally and externally after cleaning.

Open and inspect low-water fuel cut-off.

Routine burner maintenance.

Routine maintenance of condensate or vacuum return equipment.

Routine maintenance of all combustion control equipment.

Combustion and draft tests.

Safety valve pop test.

Evaporation test of low-water fuel cut-off.

Inspect gas or oil piping for proper support and tightness.

Inspection Reports A typical maintenance, test and inspection log is shown in the diagram that follows. It records daily, weekly and monthly checks that need to be carried out.

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Maintenance • Testing • Inspection Log

STEAM HEATING BOILERS BUILDING

ADDRESS

MONTH

YEAR FUEL TYPE

BOILER NO.

PERSONS TO BE NOTIFIED IN CASE OF EMERGENCY (INCLUDE NAME AND PHONE NUMBER)

DAILY MAINTENANCE INSPECTION CHECKS DATES

1

2

3

4

5

6

7

8

9

10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31

Checked by (please initial): 1. Observe Water Level 2. Record Boiler Pressure 3. Record Flue Gas Temp.

WEEKLY MAINTENANCE INSPECTION CHECKS WEEKS

WEEK 1

WEEK 2

WEEK 3

WEEK 4

Checked by (please initial):

1. Test Low Water Cut-off 2. Test Gage Glass 3. Observe Flame Condition MONTHLY MAINTENANCE INSPECTION CHECKS (Enter Date Checked) 1. Manual Lift Relief Valves 2. Review Condition of each item and/or Test each item

Relief Valve Check Date:

Date Checked

Date Checked

A. Linkages

F. Floor Drains

B. Damper Controls

G. Flame Detection Device

C. Stop Valves

H. Limit Controls

D. Refractory

I. Operating Controls

E. Flue-Chimney Breeching Weekly and Monthly Checks Performed by:

3. Observe gage glass on expansion tank 4. Combustion Air adequate/unobstructed

COMMENTS:

Maintenance, Test and Inspection Log

Maintenance of Pressure Systems The purpose of maintenance is to ensure the safe operation and condition of the system. The need for maintenance should not be confused with the need for examinations under the written scheme. The type and frequency of maintenance for the system should be assessed, and a suitable maintenance programme planned.

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A suitable system for recording and retaining information about safe operating limits and any changes to them should be used. Whatever method is used, the information should be readily available to those people who need it, including the competent person responsible for the examinations in accordance with the written scheme. For mobile systems, the owner must provide the user with a written statement detailing the safe operating limits, or ensure that this information is clearly marked on the equipment.

Record Keeping The user of an installed system and the owner of a mobile system must keep the last competent person's examination report relating to the system as well as any previous reports, if they contain information that will assist in assessing whether:

The system is safe to operate.

Any repairs or modifications to the system can be carried out safely.

These records should be kept at the premises where the system is installed in the case of an installed system, or at premises from which the deployment of the system is controlled for mobile systems. Where the user or owner of a pressure system changes, the previous user or owner must give to the new user or owner, in writing, any records kept by him or her relating to the system.

Students are encouraged to download and review the HSE publication indg261 from the HSE website at www.hse.gov.uk.

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Title

Page

Carriage of Dangerous Goods

MAIN CLASSIFICATION SYSTEMS IN PLACE FOR DANGEROUS GOODS UN CLASSIFICATION SYSTEMS HAZARD CLASSES AND TRANSPORT PICTOGRAMS LABELLING FOR SUPPLY GLOBALLY HARMONISED SYSTEM (GHS) CONTROLLING RISKS FROM THE CARRIAGE OF DANGEROUS GOODS DANGEROUS GOODS SAFETY ADVISORS DESIGN, CONSTRUCTION & CONSIGNMENT REQUIREMENTS VEHICLE PLACARDING REQUIREMENTS TRANSPORT DOCUMENTS EMERGENCY INSTRUCTIONS IN WRITING (TREMCARDS) TRAINING REQUIREMENTS EQUIPMENT REQUIREMENTS

3 3 3 6 7 8 8 10 10 12 13 13 14

BSC Level 6 Diploma – Element 1B | Applied Health and Safety Management

BSC Level 6 Diploma | Unit 1 Element 1B: Applied Health and Safety Management Study Unit 1B10 | Carriage of Dangerous Goods Learning Outcomes When you have worked through this Study Unit, you will be able to: ♦ Outline the main classifications systems in place for dangerous goods. ♦ Determine, implement, evaluate and maintain measures for controlling risks from the carriage of dangerous goods. Unit 8:

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Main Classification Systems in Place for Dangerous Goods UN Classification Systems The United Nations maintains a list of all dangerous substances that are likely to be transported. Each substance is allocated a United Nations Substance Identification Number (UN SIN), which is most commonly referred to as the UN number, with a ‘Proper Shipping Name’. Many chemicals can have different systematic, trivial or trade names, but the proper shipping name is to be used on packaging and documentation for carriage purposes. For example, ‘UN 1789 HYDROCHLORIC ACID’ has an old name, ‘muriatic acid’, but the proper UN name should be used. The UN numbers and proper shipping names are published in A European Directive called “ADR”. This is available on the UNECE website. This worldwide system of identification overcomes problems of language, pronunciation and misunderstandings that might arise from the apparent similarity of many chemical names. It helps the emergency services to obtain information quickly about the properties of a substance and the most appropriate action to take. Dangerous goods for transport are divided into nine hazard classes depending upon the nature of their danger. Some classes are further subdivided into hazard divisions to allow more specific classification. Where a substance has more than one hazard, it is placed in the class that represents its main or primary hazard.

Hazard Classes and Transport Pictograms Class 1: Explosives Class 1 includes substances that are capable of a reaction that will cause damage to the surroundings, and articles that contain one or more explosive substances. The explosive class has divisions that indicate the effects of the hazard. Explosives have their own special carriage rules. The classes are further sub-divided as follows: 

Division 1.1: Substances and articles that have a mass explosion hazard.



Division 1.2: Substances and articles that have a projection hazard.



Division 1.3: Substances and articles that have a fire hazard and either a minor blast hazard, or a minor projection hazard, or both.



Division 1.4: Substances and articles that present no significant hazard.



Division 1.5: Very insensitive substances which have a mass explosion hazard.



Division 1.6: Extremely insensitive articles which do not have a mass explosion hazard.

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(Transport Pictograms) Class 2: Gases Class 2 covers gases that are compressed, liquefied, dissolved under pressure or refrigerated. All gases present dangers, if only because they are stored in pressurised cylinders (perhaps 3,000 pounds per square inch [or psi]). The classes are sub-divided as follows: 

Division 2.1: Flammable gases.



Division 2.2: Non-flammable, non-toxic gases.



Division 2.3: Toxic gases.

(Transport Pictograms)

Class 3: Flammable Liquids Flammable liquids can give off vapours or fumes that can explode or burn if ignited by a source of ignition such as a match or spark. The vapours are often heavier than air and will sink to the floor.

(Transport Pictogram) Class 4: Other Flammable Materials Other flammable materials are sub-divided as follows: 

Division 4.1: Flammable solids, self-reactive substances and desensitized explosives.



Division 4.2: Substances liable to spontaneous combustion.



Division 4.3: Substances that, in contact with water, emit flammable gas.


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Class 5: Oxidizing Substances and Organic Peroxides In Class 5, the following sub-divisions exist: 

Division 5.1: Oxidising substances.



These substances do not necessarily burn themselves but, when in contact with fire, can produce oxygen that will cause or support a fire.



Division 5.2: Organic peroxides.



These are unstable substances that may have to be kept at very low temperatures. They will often react violently with each other and other substances, and this can cause fire or explosion.


Class 6: Toxic and Infectious Substances Class 6 is sub-divided as follows: 

Division 6.1: Toxic substances.



Division 6.2: Infectious substances.

(Transport Pictogram)

Class 7: Radioactive Material These are materials that give off ionising radiation that can damage the human body.


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Class 8: Corrosive Substances These are solid or liquid substances that destroy metals and many other materials and are damaging to human and animal skin.

(Transport Transport Pictograms)

Class 9: Miscellaneous Dangerous Substances and Articles These are substances which present a danger in transport but which are not covered by the other eight classes.


Labelling for Supply We have looked at classification and marking of containers and vehicles during transit to give information to all sections of the community. We also need to consider the marking of products and packages to give information to the end user of the substance. The pictograms below are examples of typical product supply labels and are presented in orange squares, as opposed to the diamonds indicated for transport. Symbol

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Classification and Indication of general nature of risk

Symbol Classification

Explosive

Toxic or very toxic

Oxidising

Harmful or Irritant

Extremely or Highly Flammable

Corrosive

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Dangerous for the environment

The symbols are black on an orange-yellow orange background.

The UN has recently brought together experts from around the world including the International Programme on Chemical Safety and the World Health Organisation, to improve classification and labeling systems for chemicals.

Globally Harmonised System (GHS) The problem faced by the chemical industry selling products around the world is the inconsistency between different regional and national natio systems for chemical classification. A substance which is classed as toxic in one part of the world may not be considered toxic in another. A Globally Harmonised System (GHS) is now being introduced which will tackle this problem by standardising both classification and communication. GHS is an internationally agreed System of Classification and Labelling of Chemicals. GHS aims to improve the health and safety of workers, consumers and the environment by ensuring consistent hazard communication on the chemicals being used. There will be a change to the commonly used pictograms p and symbols for hazardous substances. As is the case now, 2 types of pictogram/symbol /symbol will be used; one o for packaging and labelling of the product (which is significantly different from the current pictograms) and one for the transportation of th that product (which continues to apply the UN hazard diamonds) Under the new GHS the standard orange orange-square square hazard pictograms will be replaced with a new diamond shaped d pictogram with a red border on white background background. Examples as follows:

GHS Pictogram

GHS Pictogram

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Controlling Risks from the Carriage of Dangerous Goods The following section will outline a range of considerations and actions required to ensure the safe transportation of dangerous goods.

Dangerous Goods Safety Advisors Any organisation wishing to transport dangerous goods must ensure that they have access to technically competent assistance. There is a need, therefore, for duty holders to appoint a Dangerous Goods Safety Advisor (DGSA) to ensure that the requirements of any National and International laws are complied with. This is an essential first step. General functions to be carried out by the DGSA: 

Monitoring compliance with the rules and laws governing the transport of dangerous goods.



Advising the employer on the transport of dangerous goods.



Ensuring that an annual report to the employer is prepared on the activities of the employer concerning the transport of dangerous goods.



Monitoring the practices, procedures and activities of the employer, concerning dangerous goods.

The obligations are placed on the employer rather than the DGSA. However, the employer must provide the DGSA with relevant facilities to ensure the duties are properly complied with. 

The requirement to appoint a DGSA can apply to any person who allows dangerous goods to be carried by road, not just the transport operator. This could include anyone who consigns cargo, freight forwarders, warehousemen and manufacturers producing goods that will be collected from their factory.

Packaging Groups Most dangerous goods are assigned to one of three packaging groups to ensure that suitable packaging of dangerous goods is selected and used (Group I = high danger, II = medium, III = low). The criteria for assignment of packaging groups are specific to the classes. Transport Categories and Tunnel Restriction Codes Dangerous goods are assigned transport categories 0, 1, 2, 3 or 4. Transport categories broadly correlate with packaging groups. Restrictions are in place for some dangerous goods in relation to their transit through tunnels. Tunnel restriction codes are assigned to those dangerous goods that present a significant risk within enclosed tunnels. Entrances to affected tunnels will clearly display the tunnel code. The tunnel restriction codes are B, C, D and E and apply to the amount and type of dangerous good being carried. A dash in brackets (-) indicates that no restrictions apply.

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The following tables give examples of the transport categories and tunnel restriction codes: Dangerous Goods Transport Categories Transport Category

0

Examples of Dangerous Goods

Extremely infectious substances

All loads, no lower limit

Packing group I Toxic gases Organic peroxide Very infectious substances

20

Packing group II Flammable gases Infectious substances

333

Packing group III Non-flammable, non-toxic gases Life-saving appliances

1,000

Matches/firelighters Certain empty, uncleaned packagings

Unlimited

Extremely dangerous

1 Very dangerous

2

Threshold (kilograms or litres)

Dangerous

3 Low danger 4 Very low danger

Tunnel Codes Tunnel Code

Restrictions

─

No restrictions for the transport of dangerous goods;

B

Restriction for dangerous goods which may lead to a very large explosion;

C

Restriction for dangerous goods which may lead to a very large explosion, a large explosion or a large toxic release; dangerous goods restricted in tunnel category B,

D

Restriction for dangerous goods which may lead to a very large explosion, to a large explosion, to a large toxic release or to a large fire; dangerous goods restricted in tunnel category C,

E

Restriction for all dangerous goods other than UN Nos. 2919, 3291, 3331, 3359 and 3373.

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Design, Construction & Consignment Requirements There are very strict requirements for the design and construction of all packagings and vessels along with the test and examination requirements to ensure that they remain leakproof and otherwise safe for carriage. There is a general requirement for the safe and robust packing of dangerous goods in packagings including Intermediate Bulk Containers (IBC’s) and large packagings. There must be provisions for dangerous goods consignments to be correctly marked and labeled, and correct documentation to be provided along with with authorisation of consignments and advance notifications. Provisions are to be made to ensure all loads and vehicles are safe regarding the suitability and selection of packagings and vehicles. There are also a number of provisions made in relation to the loading, unloading and handling of dangerous goods. It is prohibited to carry out any of these activities unless all other regulatory requirements are complied with.

Vehicle placarding requirements Vehicles and containers used for the carriage of dangerous goods by road must display appropriate orange-coloured placards. The markings are dependant upon the type of goods carried, type of vehicle and type of journey. The following is a summary of the common placarding requirements. Vehicles carrying packaged goods that come within the scope of transport categories 0 to 4 must be labelled with a plain orange plate at the front and at the rear. These must be removed or covered when the vehicle has no dangerous goods aboard. If the load is below the threshold quantity, the plates are optional. The packages must be marked with: 

The proper shipping name of the material.



The UN classification number.



The appropriate diamond-shaped classification signs for the main and any subsidiary hazards.

Vehicles carrying dangerous goods in tankers, including tank containers and also including empty tanks that have not been cleaned, must have: 

A plain orange plate at the front (this does not apply to a trailer that has been detached from the tractor).



Placards on the rear and both sides showing the emergency action code and the UN number.

Alongside or integral with the placards on the rear and both sides must be the hazard warning diamond(s) and a contact telephone number for specialist advice (except for bulk solids – in this case, the telephone number is not a requirement).

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In the example of a placard above, the information is: 

Top left-hand corner (2WE) = the emergency action code (gives advice to the fire authority on action to take).



Immediately below that (2447) = the UN number of the substance being carried.



Bottom left-hand corner (0123 – 456789) = specialist advice telephone number.



Top right-hand corner = Hazard warning diamond.



Bottom right-hand corner (CHEMCO) = company consigning the load.

Emergency Action Code (EAC) The EAC provides the emergency services with information relating to the method of fighting the fire, the hazardous properties of the material and safety precautions. The first character, a number, identifies the appropriate fire-fighting method (1 = coarse spray; 2 = fine spray; 3 = foam; 4 = dry agent). The second character, a letter such as P, R, S, T, W, X, Y or Z, identifies whether a violent reaction is possible, as well as the necessary safety precautions for fire-fighters, and whether to dilute or contain any spill. The information indicated is shown in the table that follows.

Hazchem Letter Code - Examples Letter

Possible Violent Reaction

Safety Precautions

P

Can be violently reactive

Liquid-tight suit and breathing apparatus required

R S


Wear breathing apparatus with fire kit


Liquid-tight suit and breathing apparatus required


Wear breathing apparatus with fire kit

Dilute or Contain

Dilute the spillage and wash away

T W X Y

Contain the spillage to prevent entering drains or watercourses

Z

An optional third character is an ‘E’, indicating that a public safety hazard exists and evacuation should be considered. Alternative placarding An alternative placarding system is in operation across Europe and is referred to as the ‘Kemler Code’. The Kemler code consists of two or three ‘hazard identification numbers’ that identify the hazards rather than advise on action to take in the case of an emergency. The Kemler code

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is the European equivalent of the UK’s Emergency Action Code system, which was described earlier. It is an attempt to communicate the seriousness of the hazard. The system is based on the UN hazard classes. For example, Class 3 is flammable liquid; Class 8 is corrosive, etc. The code is made up of two or three digits, the first of which may be duplicated for more dangerous goods. The first figure identifies the primary hazard and the second or third identifies supplementary hazards: 

2: Gas may be given off.



3: Flammable Liquid.



4: Flammable Solid.



5: Oxidising Substance or Organic Peroxide.



6: Toxic Substance.



8: Corrosive.



9: Risk of violent reaction from spontaneous combustion or self-polymerisation.



0: First digit adequately describes hazard.

For example, acetaldehyde (UN 1089) is a flammable liquid (UN hazard Class 3) with no other hazards. It has an assigned Kemler code of ‘33’, the first number being duplicated because it is highly dangerous. A flammable liquid of lesser danger, like butanol (UN 1212), is assigned a Kemler code of 30. These numbers are usually set out with the Kemler code above the UN number:

33 1089 Transport Documents Consignors must provide carriers with information about the goods and any special requirements. This must accompany consignments. The transport document for each dangerous substance, article or material must contain: (a) UN number preceded by the letters ‘UN’. (b) Proper shipping name. (c) Class and division, and any subsidiary hazards in brackets. (d) Packaging group (if assigned) preceded by the letters ‘PG’. (e) Number and description of the packages. (f) Total quantity of each item of dangerous goods bearing a different UN Number, Proper

Shipping Name or Packaging Group. (g) Name and address of consignor. (h) Name and address of consignee.

(k) Tunnel restriction code (where assigned and applicable)

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The information shown in a, b, c, d and k must be shown in that sequence. A carrier must retain a written record of all the information in any transport document for three months after the journey finishes.

Emergency Instructions in Writing (Tremcards) Consignors are also responsible for the providing ‘Emergency Instructions in Writing’ more commonly known as tremcards (transport emergency cards) for drivers to follow in the event of an emergency. The tremcard must be kept in the vehicle cab and must be in the languages of all the countries through which the load will be travelling. Typical information includes: 

Name, class and UN number(s).



Nature of the danger, measures to be taken by the driver, and PPE.



General actions to be taken and special actions for certain goods. o

Necessary equipment for the additional and/or special actions.

o

Personal protection.

o

Fire.

o

First-aid.

Before the start of a journey, the vehicle crew must familiarise themselves with the load being carried and the emergency actions that will apply.

Training Requirements A significant element of this section relates to the competence of the vehicle crew. Drivers of all vehicles carrying dangerous goods must attend a basic training course and hold a basic training certificate issued by a competent authority. Other persons whose duties concern the carriage of dangerous goods (loaders, unloaders etc) should also receive training in the requirements governing the carriage of such goods appropriate to their responsibilities and duties. The initial training of all persons involved in the carriage of dangerous goods by road, is generally known as ‘Dangerous Goods Awareness Training’, and takes the following form: 

General awareness training: personnel are to be familiar with the general requirements of the provisions for the carriage of dangerous goods by road.



Function specific training: personnel will receive detailed training, commensurate directly with their duties and responsibilities, in the provisions of the regulations concerning the carriage of dangerous goods by road.



Safety training: personnel will receive training covering the hazards and dangers presented by dangerous goods commensurate with the degree of risk of injury or exposure arising from an incident involving the carriage of dangerous goods, including loading and unloading.

The training provided aims to make personnel aware of the safe handling and emergency response procedures, together with an awareness of the requirements of other modes of transport, where the carriage of dangerous goods will involve a multimodal transport operation.

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Details of all training must be kept by both the employer and the employee, and must be verified upon commencing any new employment. The training of personnel involved in the carriage of dangerous goods by road must also be periodically supplemented with refresher training to take account of changes in regulations. Drivers of vehicles of a certain capacity, carrying over certain amounts of specified dangerous goods are required to attend a specialised training course and pass written examinations to obtain a vocational training certificate valid for the classes of goods to be carried. This also applies to all vehicles carrying explosives and most radioactive materials. There are some exemptions to the requirement to hold the vocational training certificate including goods carried in limited quantities, quantities carried per transport unit, and vehicles under the supervision of the emergency services. Operators should keep records of all driver training. Driver training is valid for five years and drivers are to refresh their training before the expiry date is reached in order to demonstrate their continued competency.

Equipment Requirements The following is required to be carried on board the transport unit for all classes of dangerous goods 

A wheel chock



Suitable fire fighting equipment



Two self standing warning signs



Eye rinsing liquid

And for each member of the vehicle crew: 

A hi-vis warning vest



A portable light



A pair of protective gloves



Suitable eye protection (Goggles)

In addition, other types of equipment may be required based on the goods being carried. E.g. emergency escape mask, shovel, drain seal

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Title

Page

Construction and Demolition

MAIN HAZARDS AND RISKS ASSOCIATED WITH CONSTRUCTION AND DEMOLITION ACTIVITIES................... 3 MOVING AROUND THE WORKSITE ............................................................................................................................... 3 WORKING AT HEIGHT, INCLUDING SCAFFOLDING AND LADDERS ........................................................................................... 3 ERECTION OF STRUCTURES ....................................................................................................................................... 4 ROOF WORK (FALLS) .............................................................................................................................................. 4 DEMOLITION ........................................................................................................................................................ 4 EXCAVATIONS ....................................................................................................................................................... 5 MOVING VEHICLES AND MOBILE PLANT......................................................................................................................... 8 MOVING OR FALLING MATERIAL AND COLLAPSES............................................................................................................ 11 ELECTRICITY....................................................................................................................................................... 11 WORK ON, NEAR, OR OVER WATER .......................................................................................................................... 12 PRACTICAL CONTROLS FOR MINIMISING RISKS TO SAFETY .......................................................................... 13 WORKING AT HEIGHT ............................................................................................................................................ 13 EXCAVATIONS ..................................................................................................................................................... 23 ELECTRICITY....................................................................................................................................................... 28 MACHINERY/ VEHICLES .......................................................................................................................................... 34 COLLAPSE OF STRUCTURES ..................................................................................................................................... 35 FALLING OBJECTS ................................................................................................................................................ 38 SLIPS, TRIPS AND FALLS ........................................................................................................................................ 41 MANUAL HANDLING .............................................................................................................................................. 43


BSC International Diploma | Unit 1 Element 1B: Applied Health and Safety Management Study Unit 1B11 | Construction and Demolition Learning Outcomes When you have worked through this Study Unit, you will be able to:

1.B.11.1 Describe the main hazards associated with construction and demolition and explain how they may cause harm. 1.B.11.2 Determine, implement, evaluate and maintain measures for controlling risks from construction and demolition

Unit 9:

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Main Hazards and Risks Associated with Construction and Demolition Activities The most frequent causes of accidental death and injury during construction and demolition activities are discussed below.

Moving Around the Worksite Construction and demolition sites are intrinsically dangerous, with a wide range of activities that present hazards to any person who needs to move around the site. Consequently, there should be safe access onto and around the site, for both people and vehicles, and any changes of level should be minimised to prevent falls. To begin with, there is the obvious risk of falling into any excavations, or actual objects falling onto persons walking around the site itself. Construction activities generate partially built structures that present obstructions, e.g. stacked building materials. Demolition activities generate partially dismantled structures with the same problems. Construction sites generally are uneven, with variations in level, and spoil heaps, stored building materials. Plant and equipment present additional site hazards. It is important to ensure that there is safe segregation of people and vehicles from these hazards wherever possible, especially at the site entrances, vehicle loading and unloading areas, parking and manoeuvring places, and where a driver’s vision may be obstructed. There is also the additional problem of protection of the public. Whenever possible, the site should be fenced off and suitably signed which will also help to prevent access by children or members of the public, or even those intent on committing any offence, for example, theft and arson. This will protect people, especially children, from site dangers, and the site from vandalism and theft. The type of fencing will depend upon the location and the nature of the work being carried out. If the site is situated in a major city centre and is going to be there for quite a while, solid hoardings may be required. In addition, overhead protection may be required for both pedestrians and vehicles on the public highway, e.g. fan scaffold, sheeting, netting covered walkways, etc. For some jobs, the site may be shared. In this situation, the nature of the site boundary will have to be agreed, along with the system of access.

Working at Height, Including Scaffolding and Ladders One of the major hazards in construction and demolition is that a great proportion of work is done at heights. The danger of falls of people and materials affects not only those working at heights, but sometimes to a greater degree, those underneath. Falls are the largest cause of accidental death in the construction industry. Accidents involving falls could be prevented if the job is planned properly, if safe systems of work are adhered to and if the right equipment is used. Other dangers include:

Bad storage of materials.

Insufficient guarding or edge protection.

Unsatisfactory access or egress.

Incorrect method of getting equipment or tools from ground level to the working platform.

Any company that has persons working at heights should, at the very least, provide a method statement outlining the nature of the operations and precautions to be taken.

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Work from ladders, (should only be considered where a risk assessment has shown that the use of other more suitable work equipment is not appropriate because of the low risk, and short duration of the task or considerations of where the work is located), is frequently a cause of accidents. Ladders are so widely used that their dangers are often completely overlooked. They are frequently used in unsuitable locations where they form inappropriate working places, and they are often incorrectly used and poorly maintained. Incorrect selection of equipment, erection, securing and use are the main problems. Scaffolding provides a much safer working platform but can also suffer from incorrect design and erection which can lead, in the worst case, to scaffold collapse, or at least incomplete construction which can allow falls of persons or materials.

Erection of Structures By its very nature construction work involves the erection of various structures which include scaffolding to provide safe working platforms, materials and passenger hoists to transport persons and materials, and the framework, covering and roofing of the building under construction. Each of these present particular hazards that are dealt with in more detail elsewhere in this course. In addition, lifting equipment and mobile access equipment will also be involved. The stability of the structure itself is an important consideration and major accidents have arisen as a consequence of poor design, poor construction and unauthorised modification of buildings under construction.

Roof Work (Falls) People fall because access to and from the workplace is inadequate, or the workplace itself is not safe. The high-risk occupations where falls are of major concern include: roof work, steel erecting; formwork, such as shuttering and concreting; steel fixing and demolition. Roof work accounts for almost 20% of all construction deaths, and these are mainly due to falls from or through roofs. Falls through fragile materials, such as roof lights and asbestos cement roofing sheets, account for more of these deaths than any other single cause.

Demolition Typical hazards of demolition activities are discussed in the material that follows.

Falling Materials Materials may fall as a result of the intentional throwing down of materials or an unexpected collapse of part of the structure.

Premature Collapse of Buildings The main causes of accidents are premature collapse of buildings and structures; and falls from working places or access routes. A common feature of many of these incidents is a failure to plan the operation at an early stage. Lack of planning often leads to workers devising their own means of access and methods of work, both of which are inherently dangerous, so the method chosen and the sequence of work will be of great importance.

Materials of Construction The choice of materials will be affected by the various hazards that materials may present. This includes problems that will result from the presence of substances such as asbestos, silica and other dust producing substances, as well as the choice of pre-stressed materials with stored energy. The materials and the method of construction will therefore have a considerable bearing on the demolition method chosen and the sequence of work.

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Hazardous Substances The building may also contain hazardous substances such as asbestos, lead, residual flammable materials and pathogens that may lie dormant in the structure, etc. Other possible hazards could be presented by sharps and bird droppings. It is therefore necessary to survey the site for the presence of such materials before demolition begins; otherwise workers may be exposed to airborne hazardous substances.

Working Places and Means of Access/Egress The very nature of demolition work creates serious difficulties in maintaining a safe means of access and egress for workers; it is therefore necessary to keep the problem under review and update safety systems as conditions change. One of the basic means of maintaining safe access is by maintaining housekeeping at a high standard. Where scaffolding is used, platforms and gangways must be kept free from debris and tripping hazards. The security of scaffolds is important and continued surveillance is required to see that when the structure is demolished, sufficient ties are maintained with the building. Where there is a possibility of falling debris injuring work people or pedestrians, protective fans must be constructed. It is important to remember that fans are not designed to carry heavy loads, and regular inspection must be made to see that debris that has inadvertently fallen is cleared away. Securing of ladders is another problem area. As the structure is lowered and ladders removed to lower levels, or moved to different positions, the temptation to put them in position and go back to work without making them secure is ever present. Some operations require the demolition worker to occupy precarious positions where it is not possible to provide an adequate safety structure. Here it becomes crucial that safety harnesses are used and attached to a secure part of the structure. Where floors have been removed, some boards should be left so there remains a skeleton floor structure to allow work to proceed in relative safety.

Security of Site Boundaries A considerable amount of demolition is carried out by undermining a structure, and causing collapse of material. The amount of material will vary but, irrespective of the quantities involved, one general principle that emerges is the need to isolate the demolition area so that potential hazards may be confined. This precaution will also help to exclude from the site persons not directly involved in the work.

Excavations Excavations can cause fatal accidents due to the following issues.

Collapse Excavations are particularly related to the construction of foundations, drainage work and site re-grading. The main hazard associated with excavation work is ground collapse; no soil can be relied upon to support its own weight for any length of time, a factor that becomes increasingly important as additional loads are applied, such as those from plant and materials. Even a minor collapse can cause serious injury (1 m3 of earth weighs approximately 1.3 tonnes). If an excavation cannot be battered (sloped back) to a safe angle, or benched or stepped, the sides will require support to prevent the possibility of collapse. When a collapse occurs, the worker will most likely be knocked over and the weight of the soil on the body will be sufficient

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to cause a serious crushing injury (or be fatal), even if the arms, head and shoulders are not covered. There is a widespread belief among those who investigate excavation accidents that they are caused because of a general lack of knowledge about the structure of soils by those involved in digging operations. Many excavation collapses occur during the first day of the dig; some are delayed for several hours, while others can occur within minutes. The time factor often depends upon the type of soil involved and the soil structure. Equivalent soils may not exhibit the same hazardous nature if their structures differ.

Access The use of access ladders that are badly sited, both on the floor level of the excavation and in respect of the overhang available to get on to the ladder at ground level, can lead to people slipping or falling off. There is also a risk that people might climb on support systems and fall or dislodge them increasing the potential of the excavation collapsing.

Falls of People and/or Materials If an excavation or opening in the ground, such as an open manhole or a shaft has unprotected edges people or vehicles are at risk of falling in, often due to it not being noticed. If materials are stored near excavations, precautions must be taken to prevent them falling into it, such as chocks and wedges for pipes and toe boards for preventing smaller materials such as tools being knocked in.

Use of Transport Badly constructed ramps used for vehicular access to the excavation can cause vehicles to topple over into the excavation. Machinery/vehicles working or parked too close to the edge of the excavation could cause a collapse resulting in the vehicle falling in possibly where ground workers may be working. The vibration caused by machinery may also increase the likelihood of a collapse in unsupported excavations.

Flooding Flooding may occur as a result of weather conditions (rain or melting snow), of digging into and beyond the natural water table of the land or of disruption to the natural drainage flows within the ground. Changes in the level of the water table (as a result of rainfall) may also cause flooding. This is unlikely to present a significant risk to people working in the excavation except where a watercourse is breached, and there is a massive surge of water into a confined space such as a trench.

Buried Services The term ‘buried services’ means all underground electricity, gas, water (including piped sewage), and telecommunications systems. Electrical Cables Every year many workers digging on building sites and roadworks have narrow escapes when they accidentally hit live buried electricity cables; others are not so lucky and suffer burns that may prove fatal. Injuries resulting from damage to live electricity cables are usually caused by the explosive effects of arcing current, and by associated fire or flames which may follow when the sheath of

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a cable and the conductor insulation are penetrated by a sharp object such as the point of a tool. When a cable is crushed severely enough to cause internal contact between the conductors, this causes severe and potentially fatal burns to the hands, face and body. Direct electric shock is rare but not impossible. Gas Pipes Damage to gas pipes can cause leaks which may lead to fires or explosions. There are two types:

Damage that causes an immediate leak being a risk to people carrying out work and to others in the vicinity.

Damage that causes a leak at a later date. The damage may occur at the time the work is carried out, for example, damage to a pipe wrapping may eventually lead to corrosion. Damage may also occur subsequently, for example, reinstatement may leave a pipe inadequately supported or subjected to unequal forces.

Water Pipes and Sewers Damage to water pipes is less likely to cause injury but a jet of water from a high-pressure main could injure a person or damage adjacent services. A leak of water from an underground pipe could wash away subsoil and reduce the support for adjacent services, highways and structures. Further dangers include the risk of flooding the trench or low-lying areas such as nearby basements. Some sewage is pumped at pressure. The main danger from damage to a sewer is the possibility of contamination. Telecommunications and TV Cables Telecommunications and TV cables may also be a problem if not identified correctly. These can be not only expensive to replace, but can also cause extensive disruption to communication networks of individuals and businesses that use them. Risks of direct personal injury are low if such cables are damaged. Problems can arise, however, if any flammable or toxic gases gain entry to cable carrying ducts, especially if such ducting is damaged. Accumulation of such gases can cause more serious problems, and pose a great risk, if present, to those working in the vicinity.

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Moving Vehicles and Mobile Plant Construction plant can be heavy. It often operates on uneven ground and rough muddy terrain. People walking on site are often injured or killed by moving vehicles, especially reversing ones. Drivers and operators are killed or injured by overturning vehicles and plant. Any situation that involves crossing a vehicle traffic route is a hazard, particularly where visibility is restricted and it is not possible to see the approach of vehicles clearly. Emerging from doors can present a problem where the exit leads straight on to a vehicle path, or if vehicles are obscured by building debris, stacks of scaffolding, etc. Other hazardous situations include:




The hazards involved in vehicle operations in the workplace may be divided into three groups: •

Loss of control – where the vehicle is not under the full control of the driver.

•

Overturning – tipping over onto the vehicle’s side or onto its front or back.

•

Collisions with other vehicles, pedestrians or fixed objects.

Note that the harm from any of these hazards may be to one or more of the following:

The vehicle itself.

The driver.

Other people in the vicinity.

Buildings, plant and equipment in the vicinity.

Mobile work equipment may include: dumpers, forklift trucks, mobile cranes, land rovers, concrete wagons, etc. Pallet trucks, sack barrows, wheelbarrows, compressors and concrete pumps are not regarded as mobile work equipment. Limited visibility may also present hazards and may be due to obstructions, such as vehicles, stacked material, etc. Parked vehicles should not be allowed to cause obstruction to sightlines. This can be a problem where vehicles are stopped for checking on leaving premises. Lay-bys should be provided wherever appropriate. Site vehicles should use flashing beacons when entering or in use on site. Environmental conditions may not only affect the road surface, such as through excess water, mud, snow, ice and fog, but may also affect visibility, such as sunlight suddenly blinding a driver. Similarly, any blind spots should be eliminated or, if this is not possible, visual aids such as convex mirrors should be used to aid movement around the site. Sufficient and suitable parking areas should be provided for all vehicles using the site – including employees’ and visitors’ private vehicles. If vehicles are left in unplanned areas, the safe operation of the site may be jeopardised – for example, by obscuring sight lines. Poor lighting may also affect visibility. Adequate lighting is essential for safe and efficient operations, as well as for security purposes. Outside areas which may have natural daylight

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will require artificial lighting when it is dark and during weather conditions which restrict visibility. Increased levels of lighting may be necessary in certain circumstances – for example: •

At junctions of traffic routes.

•

Where traffic routes are close to buildings or plant.

•

In pedestrian areas.

•

Places where there is regular movement of vehicles and other mobile plant.

Lighting columns close to the edges of routes can cause difficulties as they may present an obstruction and, if they cannot be set back, overhead or wall-mounted lights should be used instead. The sight lines of traffic routes must be carefully considered to ensure that drivers can see ahead and around them, and so that others can see them. Hazards such as sharp bends or blind corners should be eliminated where possible by, for example, lowering or removing walls, stacks, etc. at corners and junctions. Where this is not possible, warning signs, hazard markings and mirrors can reduce the risk. Assuming driver competence, collisions with other vehicles, pedestrians or fixed objects are generally caused by adverse local conditions: •

Poor weather: ice or rain causing skidding or longer braking distances; sunlight blinding vision; rain or fog restricting visibility.

•

Poor lighting: decreasing visibility or obscuring parts of the traffic route, including obstructions.

•

Poor sight lines: causing blind spots and concealed junctions.

•

Poor ground surface: uneven muddy or slippery surfaces or excessive slopes.

•

Congestion due to there simply being too many vehicles in one area.

Speed limits should be set and enforced on all parts of the site. They should take into account the environmental hazards, presence of pedestrians, the conditions of the road surface, the types of vehicle and the operations they are involved in. Particular restrictions may apply in certain parts of the site, especially where pedestrians are close, such as in loading/unloading bays. As enforcement is often difficult, speed restrictions such as chicanes or ‘sleeping policemen’, accompanied by prominent warning notices, may be used to prevent vehicles being driven at excessive speeds. The above measures may be used to avoid vehicles colliding on site. Identification of the hazards presented by vehicle operations needs to take account of the following factors: •

The required patterns and volume of vehicle movement in and around the workplace, including access to and egress from it to the public roads.

•

The types of vehicle on the premises.

•

The types of operations undertaken by vehicles in the workplace and the types of load being moved, e.g. tracked vehicles, excavators and the movements involved in their operations.

•

The need to segregate vehicles and pedestrians.

•

The impact of different weather conditions.

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•

The local environment – conditions of the roads, lighting and sight lines.

The way in which such vehicles move around a site should be carefully controlled, and be appropriate for the types of vehicle operating on the site, for example, tracked or vehicle mounted. This needs to be carefully thought out and can have wide implications – for example, the circulation of vehicles collecting rubbish from skips and bins, and their need to park during operations, may affect the siting of the rubbish containers or require special vehicular access routes to them. Another example is the operation of an excavator, which could result in possible collisions with people, structures, plant and equipment. Adequate precautions should be used to alleviate this, for example, segregation of vehicles and barriers. If the hazard cannot be eliminated, then measures could be used, such as safe systems of work, using speed limits, instruction, training, changing the site layout and using safety devices on vehicles. Any situation that involves crossing a vehicle traffic route is a hazard, particularly where visibility is restricted and it is not possible to see the approach of vehicles clearly. Emerging from doors can present a problem where the exit leads straight on to a vehicle path, or if vehicles are obscured by building debris, stacks of scaffolding, etc. Other hazardous situations include:




Assuming that the driver is competent, hazards are also posed by the possibility of collisions with other vehicles or fixed objects. These are generally caused by adverse local conditions, such as:

Poor weather, such as ice or rain causing skidding or longer braking distances, sunlight blinding vision, rain or fog restricting visibility.

Poor lighting, such as decreasing visibility or obscuring parts of the traffic route, including obstructions.

Poor sight lines, such as causing blind spots and concealed junctions.

Poor ground surface, such as uneven muddy or slippery surfaces, or excessive slopes.

Congestion, that is, there simply being too many vehicles in one area.

Falling Loads Such collisions may be the result of accidents themselves or the consequences of unprotected moving parts being too close to pedestrian walkways and pathways.

Accidents involving moving objects may be where normally secured objects break loose and hit people, such as a container sliding down a slope, or during transport of material on site.

Flying objects are usually the result of an accident, such as parts being ejected from a machine or a broken drill bit coming off. They may be naturally occurring parts of work activities, such as waste materials flying out from drilling or cutting operations, e.g. when stone, concrete or rock are being broken up or entry of cement and other fumes, smoke, dust into the eye. Roofing sheets and plywood could cause a hazard if not secured properly, especially if stored at height.

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Being hit by falling objects is one of the most common hazards associated with construction site work. Any unsecured object near an edge or on a sloping surface may be liable to fall given a vibration or a push (even from the wind) and injure someone passing or working below. This can include materials on shelves or the tops of pallets, badly stored bricks, unsupported roof trusses propped against a wall, loose materials on scaffolding or working platforms, deteriorating brickwork or where edges are unprotected. Unstable access equipment can collapse or overturn. Poor housekeeping and incorrect methods of getting materials, equipment or tools from ground level to the working area or vice versa can also constitute a hazard.

Striking Against Fixed or Stationary Objects This may occur as a result of objects projecting out into areas where people walk or simply being placed in a position where people may walk or run into them. For example:

Poor stacking may leave pipes, rods, projecting reinforcement bars or pieces of timber sticking out from the main level of such materials.

The edges of scaffolding, or even the cross-poles themselves, may be at a level where people might walk into them.

Bricks, boxes and containers of materials may be left outside buildings, etc. awaiting removal or use.

Any of these situations may be made more dangerous where visibility for the pedestrian is restricted.

Moving or Falling Material and Collapses People can be struck by material falling from loads being lifted and material that rolls or falls, or is dropped, off work platforms. Others are struck or buried by falling materials when excavations, buildings or structures collapse. Structural collapse can range from walls that fall because their foundations are undermined by nearby excavations to buildings that collapse prematurely during demolition. Scaffolds collapse because ties are either forgotten or removed too early during striking or alteration, or because the scaffold is overloaded. Structures under construction, for example, steel frames that have not been adequately braced, or formwork that is prematurely loaded, may also collapse.

Electricity People suffer fatalities, electric shock, burns and injuries from falls, as a result of working with electricity. Such injuries may occur, for example:

When they use unsafe equipment.

When they make contact with overhead power lines and buried cables.

Due to the lack of maintenance or abuse of equipment.

When services are not isolated correctly, e.g. during demolition, excavation or other site activities.

Such work takes place outdoors and in all types of weather. This could involve working in wet or damp rainy conditions, which would inevitably increase the potential to receive an electric shock. Other problems that may be encountered are the constantly changing work environment as the various stages of construction proceed, with the possible inducement to improvise supply systems temporarily. Clearly there is a risk of damage to both temporary and fixed electrical installations in such cases. For example, cable damage that could be caused by

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the movement of any heavy plant or materials that may be exacerbated by heavy congestion on site at busy times. Similarly, the temporary site distribution must be controlled by a safe system of work, for example, a permit-to-work to ensure which parts of the systems are either live or dead. The systems themselves might be used be used by various contractors of varying competence, and might make use of equipment which is either not correctly authorised for use or which may be faulty. Generally electricity supplies above 33,000 volts are routed overhead. Below this voltage they may be overhead or underground. Overhead lines are normally un-insulated and can be lethal if contact or near-contact is made. Electric arcs may jump a considerable distance. Care should be taken when erecting structures, dumping, tipping waste, regrading, landscaping, or in unplanned storage areas, etc. not to reduce minimum clearances. Contact with overhead electric lines is a regular cause of death and injury. Any work near electric distribution cables or railway power lines must be carefully planned to avoid accidental contact. The most common operations leading to contact with overhead lines are:

Handling long scaffold tubes.

Handling long metal roof sheets.

Moving long ladders and tower scaffolds.

Operating cranes and other lifting plant.

Raising the body or inclined container of tipper lorries.

The use of mobile elevating work platforms (MEWPs).

Erecting marquees or large tents at exhibitions or certain venues.

Work On, Near, Or Over Water Certain workplaces over, on or near water present a risk of people slipping, tripping, falling or being knocked into water. Similarly, loss of balance or failure of ropes or lines or failure or absence of barriers may cause problems. In addition, strong currents, waves and a rapidly rising tide or even passing swell from water traffic may cause a person to be swept off their feet. The immediate danger to personnel is that of drowning, but other factors which might need to be thought of are:

The shock of sudden immersion in cold water (cold shock).

The weight of waterlogged clothing.

Incapacity following injury, e.g. by striking an object during the fall or in the water.

Fatigue or hypothermia where rescue is not immediate.

The risk of catching Leptospirosis (Weil’s disease) caused mainly from the urine of infected rats which can enter the body through unprotected cuts and scratches and can be fatal if not treated. This occurs mainly in still and slow moving waterways.

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Practical Controls for Minimising Risks to Safety Working at Height One of the major hazards in construction is that a great proportion of work is done at heights. It is considered best practice to always follow a simple hierarchy for managing and selecting equipment for work at height:

Avoid work to height where possible, for example, by planning work and working from the ground.

Use work equipment or other measures to prevent falls where work at height can not be avoided.

Where the risk of a fall can not be eliminated, use work equipment or other measures to minimise the distance and consequences of a fall, should one occur, taking into account the duration and environment in which the work is to be completed.

Such a hierarchy for working at height may typically involve avoidance, prevention or mitigation.

Avoid Avoidance could be achieved by designing out the need to work at height, for example, by erecting handrails or edge protection, or by transporting materials in nets from a lower floor.

Prevent Prevention could be achieved by:

Using an existing place of work, for example, a flat roof with permanent edge protection, to gain access.

Using collective work equipment, such as: guardrails, MEWPs, scissor lifts, cradles, tower scaffolds and independent scaffolds.

Using personal work equipment, for example, a work restraint system such as harness and lanyard that prevents people getting to a place where they might fall.

Mitigate Mitigation could be achieved by:

Minimising the distance of a fall and its consequences by collective means, for example, nets and air bags.

Minimising the distance of a fall and its consequences by personal means, for example: −

Rope access – a personal fall protection system that makes use of two ropes secured to different anchors; one secured to the harness, while the other is a backup.

−

A work positioning system – a personal fall protection that is connected to a reliable anchor and uses a harness, for example, a boatswain’s chair.

−

A personal fall arrest system that uses a harness connected to a reliable anchor.

Minimising the consequences of a fall by collective means, for example, nets at a lower level or soft landing systems.

Minimising the consequences by personal means, for example, by wearing a life jacket when working above or next to water.

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Minimising the consequences through training and instruction, for example on the use of ladders, step-ladders and stilts.

Safe Working Platforms Scaffold Simple Independent Scaffolds Before we discuss particular types of scaffold, it is important to understand some of the terminology used. •

Standard A standard is a vertical tube used as a support for transferring a load to the ground or to a base plate.

•

Ledger A ledger is a horizontal tube tying a scaffold structure longitudinally; it may also be used as a support for transoms or putlogs.

•

Transoms A transom is a tube spanning across ledgers to tie a scaffold transversely; it may also be used to support a working platform.

•

Brace A brace is a tube fixed diagonally across a scaffold to prevent lateral movement and to improve stability of the structure.

•

Raker A raker is an inclined load-bearing tube attached to a scaffold, which may bear on the ground or on an adjacent structure.

•

Tie A tie is a tube used to connect a scaffold structure to a reveal tie, through tie or rigid anchorage. Its purpose is to ensure complete stability of the structure.

•

Coupler A coupler is a scaffold fitting which, by a friction grip applied to the external surface of two tubes, holds them together. There are around six types in common use.

•

Base Plate A base plate is a flat square steel plate with a locating pin that must be inserted into the bottom of a standard to provide a bearing surface for load distribution.

•

Sole Plate A sole plate is a strong timber plank wider than a base plate and long enough to be positioned under at least two base plates. They provide extra load distribution capacity for the scaffold base. They must be used where the load-bearing conditions of the ground are poor, but it is good safety practice to use them for all scaffolding structures irrespective of ground conditions. If the standard is resting on concrete or pavement, a ‘plastic’ sole plate can be used which fits under individual base plates.

An independent tied scaffold is designed to carry its own mass and the full load of all materials and workers used on the scaffold. The total load is supported by the ground on

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which the scaffold has been erected. The scaffold is not totally independent and must be tied to the building where it is sited, to give the stability that prevents any possible movement of the scaffolding away from or towards the building. As the total mass of the structure when in use is supported by the ground, it is very important that the ground structure be suitable to cope with the load. The use of base plates and sole plates becomes a vital safety consideration in spreading the load. The following figure illustrates a typical independent tied scaffold.

Independent Tie Scaffold Independent tied scaffolds are also classified into three main types:

Light-duty where only one platform is used at any one time. These are used for painting and stone cleaning.

General-purpose where up to four working platforms can be used. These are used for general maintenance with loaded materials.

Heavy-duty which provides two heavy-duty working platforms and two other platforms for light duty and access. These are used for heavy masonry work or where large building blocks are used.

The basic requirements for working platforms on scaffold are guardrails, toeboards and wind protection for boards. The platform must be fully boarded but the width varies with the type of work being undertaken. Platform widths can vary from three to seven boards:

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Three boards are used for footing, i.e. for people to work without materials deposited or as a gangway.

Four boards for footing and storing materials.

Five boards for general work.

Six boards for masons and their materials.

Seven boards for masons using trestles.

Where materials are deposited, a clearway of 0.43 metres is required; when passage of materials is needed, 0.64 metres must be maintained. A guard-rail must be fitted which should be at least 950mm above any edge from which a person can fall. Any gaps between guard-rails and the top of toe board must be fitted with an intermediate guard rail and any gap must not exceed 470mm. The toe board must be suitable and sufficient to prevent falls of persons or materials.

Mobile Tower Scaffold Mobile tower scaffolds are commonly used for painting and simple maintenance jobs on buildings. They have one working platform accessible by a ladder that must be fitted internally and are light-duty scaffolds only. They can be constructed using normal scaffold tubes, but are more often proprietary made structures. The structure is mounted on four wheels so the unit can be moved about with relative ease. The height of a mobile tower scaffold is generally limited to 12 metres except for special purposes. For internal use, the height should not exceed three and a half times the shortest base dimension. When used externally the factor is reduced to three. When used above 9.8 metres, some form of guy rope, ballast or anchoring device must be used to give added stability. Outriggers are used to spread the base dimensions and increase stability.

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Mobile Tower Scaffold The working platform should conform to the standards laid for other scaffolds, e.g. toeboards and guardrails. The recommended maximum distributed load is 145 kg/m−2. When in use, the following factors are considered essential:

The tower must be set up on level ground.

Stabilisers with pad feet or outriggers with castors should be used to increase the effective base size, and should be positioned to make the base dimensions as large as possible.

The wheels must be locked to prevent motion.

The scaffold must only be moved by pushing or pulling at the base.

The scaffold must not be moved while workers and materials are on the platform.

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Mobile Elevated Work Platform The term Mobile Elevating Work Platform (MEWP) covers pedestrian-controlled, self-propelled and power-operated mobile elevating work and access platforms. MEWPs are used as temporary work places giving access to various places of work. Examples include cherry pickers and scissor lift work platforms. They are simply a platform supported by a powered mechanism that allows it to access certain workplaces by means of a chassis. The operator can drive this type of machine from the basket. The machines are controlled from the working platform, with secondary controls at ground level. Typical working heights reach from 12 m to over 20 m. General Information The MEWP is designed to provide a temporary working platform that can be easily moved from one location to another. It is particularly suitable for short duration tasks, where the use of a ladder would be unsafe and the erection of a scaffolding platform would be time-consuming or impracticable in relation to the job to be done. Some units have specialised applications. The legal duty of the employer in respect of this equipment is to provide, as far as is reasonably practicable, a safe place of work and the necessary training and supervision. The manufacturer or hire company who supplies the platform must provide all the information necessary to ensure that the user is not exposed to any risk or danger when the platform is used correctly. The MEWP is becoming widely used in more complex forms. It is essential that no one should be allowed to use the equipment unless they have been instructed and trained by a competent person on the specific type of equipment to be used. Types and Applications The basic types of mobile elevating work platforms are:

Scissor lift.

Telescopic boom or jib.

Articulating and telescopic boom.

All of these may be either:

Towable units.

Vehicle-mounted.

Self-propelled.

Pedestrian-controlled.

Rope Access Use Rope access is used for inspections, and for some short-term construction work. This technique should only be used where access from a working platform is not practical. Risk Assessment A risk assessment must be carried out prior to use of rope access. In addition, rope access must only be used within a defined system of work. When the system of work is drawn up, account must be taken of general risks from rope access operations. Attention should also be

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paid to the particular risks that are present, and can be foreseen, for that specific job. The safe system should specify:

Rescue arrangements.

Selection of correct equipment.

Selection of people with the necessary level of competence.

Arrangements for control and communication.

Types of Rope Access Working in Suspension (Descent and Ascent) This type of rope access covers most situations, such as building exteriors. It falls into the following categories: •

Straightforward In this case, the rope follows a simple, straight path from the anchor point to the ground. Workers can use relatively simple techniques for descent and ascent, as well as rescue.

•

With Deviation In this method, the rope is pulled a small distance away from the vertical during descent. This is slightly more hazardous than the previous example, and requires slightly more advanced technique.

•

With ‘Re-Belays’ In this case, intermediate anchor points are required between the top and bottom of the descent. A single descent to the ground is not possible, and a major improvement in technique over previous examples is needed. The hazards will increase further in the case of use of this method to perform a rescue.

•

Without Clear Egress at Bottom This method is potentially hazardous. It will therefore require a significant further increase in technique, including competence in long ascents and special rescue methods.

In any of these cases, the situation may be complicated by other factors, such as:

Difficulty in reaching the point of descent.

Lack of convenient anchorages.

Presence of sharp edges.

Complex structure.

Busy worksite.

Proximity of roads or other public thoroughfares.

Other objective dangers.

Aid Climbing and Traversing This type of rope access is used in situations where a special method, making use of special techniques, is needed. The work situation in which a worker carries out the task may be particularly hazardous due, for example, to conditions such as: heat (glass atria), possibility of falling, and difficulty of rescue. A risk assessment must be carried out, and appropriate access,

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rescue plans and equipment must be provided. Only qualified and trained workers should make use of this method. Safety Features The use of rope access can be made less hazardous by following certain safety features:

A competent person must supervise the erection of all equipment, which must be prechecked prior to use.

A competent, trained person only must make use of rope access.

A single suspension point should not be used. Both the main and safety ropes should be attached to separate suspension points, where possible, to increase the safety of the descent.

Equipment must be checked before use and maintained during use to a high standard.

Tools should be attached to the operator by means of ropes or chains to prevent the risk of objects being dropped.

Where a risk of dropped tools exists, the area below should be fenced off or protected in some way, for example, with covered walkways.

Safety Nets/Airbags Safety Nets Safety nets can be used to great effect during installation work. When combined with a complete perimeter edge protection, they are the most effective means of securing the fall hazard. They can also offer protection to those who work or pass below. They are collective, in that they protect all who have to work where they are in use, and they are passive, in that no action is required to experience protection. While they do not prevent falls, they do minimise the consequences of a fall. A rescue method for a person who does fall into the safety net is required as that person may be injured. Safety nets should always be installed as close as possible to the working platform, and should extend the required ‘catching width’ ahead of any leading edge. Changes in safety net technology have significantly reduced the sag between supports, and improved the energy absorption of the net systems. The result is safety netting with half the weight of the traditional material, that is constructed in square mesh, and that should not sag by more than 10% of the span. With primary steel spans typically less than nine metres, even with the safety net connected to the bottom of the portal frame, the distance from the working platform to the surface of the net is comfortably less than two metres. In this position, nets can be considered as a guard to the hazard, rather than a fall-arrest system. A debris mesh overlay can be placed upon the safety net to catch small tools and material fragments. This allows work to continue below the leading edge of the roof, which can be a great advantage on critical programmes and in re-roofing applications. Safety nets should comply with the relevant performance standards, and should equally be erected to the current standards and codes of practice. This work should either be carried out by specialists or after adequate training, and particular attention must be given to the positioning and strength of the safety net supports. Safety nets require regular inspection and maintenance, as their performance deteriorates over time. It is extremely important that the inspection and test regime is followed and this

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requirement, combined with the opportunity to match the net size with the need, makes the hire of safety netting an attractive proposition. The provision of safety netting should be considered beneficial in most areas of roofwork. It should be erected as soon as possible in the construction programme, to provide maximum protection, and should be left in place for as long as a leading edge or fall-through hazard exists. Selection should be the result of a complete risk assessment and an overall hazard management programme, and it should form part of a total package of site safety measures. When planning the use of safety nets, the above technical aspects should be taken into consideration. It is feasible to pre-position safety net attachment points (welded lugs) onto primary steelwork, for use when erecting the building. They would then be available to support safety nets when building maintenance is required, e.g. replacement of roof lights and also for eventual demolition. Safety nets can be connected by designed attachment points or by flexible tie ropes to primary steelwork of suitable capacity, or to other selected anchorage points. Nets can be moved and removed as the work progress demands. Air Bags Air bags are designed to reduce the number of injuries and deaths resulting from a fall from height. The cushioned reusable air bags are usually 0.55m high and weigh less than 7kg each, although there are varying standards. They are filled with a type of ‘memory’ foam that enables them to retain their original shape. At the same time, the air bags provide a more yielding surface on which to fall. Air bags can be used in the construction industry, for instance, to reduce the working height for construction workers to less than 2 m. For example, most two-storey houses will mean construction workers operating at a height of between 2.3 and 2.5 m. This is particularly useful where it would be difficult to provide secure fencing to protect workers. Instead, the height is reduced and the bags themselves will protect the workers should a fall occur. It is extremely important to ensure that the bags are positioned correctly before work commences. The bags should be clipped together to ensure that they do not separate should anyone fall onto the junction between two bags. The bags should also be checked when repositioned or after a fall has occurred to ensure that they have not been damaged in any way. It is also important to ensure that other control measures are in place to prevent a fall from occurring in the first place. This bag system is really a last resort and should not be relied on as the one and only control measure. It is important to remember that a fall even onto a ‘safe’ place could be very stressful and traumatic for an individual.

Fall Arrest Equipment Belts Some aspects of steel erection may also permit the use of belts, as may maintenance work of short duration and window cleaning. Although workers are often tempted to wear belts rather than harnesses, harnesses give a falling person a far greater chance of avoiding serious injury. Even after a fall of one or two metres, tremendous force is exerted on a body that is suddenly restrained by a safety rope or wire. However, the problem can be largely overcome by the use of a harness, which spreads the load more widely, or by using shock absorbing lanyards or fall arrest blocks.

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A Fall Arrest Block and a Camlock Rope Arrestor Harnesses The provision of a safe place of work and system of work to prevent falls should always be your first consideration. However, safety harnesses can provide vital protection in some circumstances. Remember, a harness will not prevent a fall - it can only minimise the risk of injury if there is a fall. The person who falls may be injured by the shock load to the body when the line goes tight, or when they strike or rebound against parts of the structure during the fall. A shock absorber fitted to the harness lanyard can reduce the risk of shock loads. In any case, allow for a free-fall distance of no more than two metres. Wherever possible the harness lanyard should be attached above the wearer. Additional free movement can be provided by using running lines or inertia reels. Any attachment point must be capable of withstanding the shock load in the event of a fall - you may need expert advice.

Consider how you will recover anyone who does fall.

Make sure everyone knows how to check, wear, adjust and attach his or her harness before use.

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A Full Safety Harness with Fall Arrest Block It is strongly recommended that a safety harness (to BS 1397) is also worn by everybody working from a MEWP. It should be attached to a secure anchorage point within the platform. The use of harnesses will prevent personnel from being catapulted out of the platform in the event of:

The base being struck by another vehicle.

Hitting an obstacle.

A wheel going into a pothole.

The whiplash effect on undulating ground.

It will also prevent falls due to overreaching or overbalancing by the operator. A safety harness must never be attached to anything outside the platform; operation of the controls in this situation could leave the user stranded in mid-air.

Excavations Excavation collapses may be prevented if:

Workers are trained in the safe installation of basic systems of safety.

The basic safety equipment is provided on site, and used.

Adequate and competent supervision is provided to ensure that correct safety precautions are observed, and assessments are made of changes in conditions that might necessitate changes in levels of safety.

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It is important when plant is being used that adequate stops or wheel chocks are put in p place to prevent vehicles from running into the excavation. Safe control of material being dug from an excavation is in general covered by checking that any stock piles are set well back from the edge of the excavation. This will cover two possible problems:

Materials falling back into the excavation.

The weight of excavated material undermining the edges of the excavation.

Basic Excavation Support Systems The main function of excavation supports is to prevent falls of material into the excavation and to allow low work to proceed safely and without interruption. The type of support structure will vary in design depending upon the soil conditions and the type of excavation, e.g. trenches or pits. Battered Sides This technique will allow almost any excavation to be carried out safely without the need for a support system. The technique relies upon the property of particulate materials to form a stable sloping pile when allowed to form naturally into heaps. The sloping surfaces of the heap form an angle with the horizontal called the angle of repose. Each material has its own particular angle of repose,, which will differ with the moisture content.

The Angle of Repose It is very easy to demonstrate the variations of the angle of repose between materials by taking ng a quantity of material and pouring it into a pile on a flat surface. If an excavation is carried out and the side sloped back to the angle of repose, then the soil will support itself without the need for extra support. It is important that the angle of o repose of the soil being excavated is known, especially if the soil has several strata, and also that the battered sides are kept at this angle during the digging operation. The technique has one drawback in that it requires considerable space in which to construct an excavation, but it should be remembered that accidents in correctly battered excavations are very rare. Note that predictability is limited to uniform soils of known water content.

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Double-Sided Support In this system, the soil on each sid side e of the excavation is supported by a structure that is held in position by forces transmitted through waling and struts from opposite faces. Provided the support ort system is strong enough, equilibrium is set up which keeps the structure secure. This is illustrated lustrated in the following figure. The technique is widely used not only in trenches with two faces, but in pits or shafts with four faces. It has the disadvantage that the struts tend to impede the working space. As the structure relies heavily upon secure secure strutting, it is very important they are securely fixed to prevent ‘accidental’ removal (deliberate or otherwise). Double sided support can be timber, as shown in the illustration, but it can also be achieved using trench sheets or sheet piles. These would would be supported by hydraulic struts, D frames or acro-props.

Double Sided Support Shields or Drag Boxes These devices are provided mainly as protection for workers in the excavation rather than for excavation support. Drag boxes comprise of two flat-bottomed bottomed side panels with tapered cutting edges to their leading ends. The panels are braced apart by tubular struts, the leading strut being specially strengthened to allow for the dragging of the box by the excavator. The side sheets are kept apart by struts that span the width of the device, thus producing a rigid box. As work advances, the box is pulled forward by the excavation machine to the next work location and the excavation behind is left open. Such boxes are simple to make and, as they are rigid igid structures, require little maintenance. Inevitably, though, they are heavy and the excavator has to be powerful enough to pull them forward in the trench. Boxes are intended to provide a secure working area for operatives rather than providing an effective ef means of preventing ground movement, hence they are often referred to as ‘shields’ ‘shields’.. Operatives should ensure they enter the trench within the area protected by the shield – not from front or rear, where protection is not present. Another form of shield is the trench box, which incorporates

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similar rigid sides like a drag box but has hydraulic struts and is lifted into position rather than being dragged. An illustration of a drag box follows.

Drag Box Benching Benching is a process of stepping off the earthen walls of an excavation and is used as a method of protecting employees from cave-ins cave ins by excavating the sides of an excavation to form one or more horizontal steps, usually with vertical or near near-vertical vertical surfaces between levels. Benching can n be single or multiple as indicated in the diagrams that follow.

Single Bench Excavation

Multiple Bench Excavation

Stepping Stepping can be used as a system by itself or in conjunction with benching. The next diagram illustrates the stepping system.

Stepping

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Ventilation in Excavations It is important that the air in the working place in an excavation is kept satisfactory for safe working. Possible hazards that may arise are:

Toxic or explosive gases seeping into the workings from defective pipelines or sewers.

Toxic or anoxic gases from internal combustion engines or leaking LPG cylinders.

Where excavations are carried out in urban or industrial areas, it would be prudent in deep excavation to arrange for hygiene testing of the working environment. Improved ventilation is commonly achieved by blowing sufficient large volumes of clean air into the excavation. The clean air will not only disperse any gas present, but will also provide a suitable atmosphere to work in. Any devices used to provide such ventilation should be fitted with a warning system that is either audible or visual, in the event of its failure. Oxygen depletion can occur when toxic or flammable gases are present:

During a particular work activity, such as welding.

From nearby internal combustion engines.

From a chemical/biological reaction such as rusting, oxidation or bacterial growth.

From a reaction between chalk or limestone and groundwater, which can produce carbon dioxide and displace any oxygen present.

Similarly, care is required to ensure that any gases discharged from plant or equipment exhausts do not enter the excavation and deplete the oxygen. Explosive atmospheres can also arise from propane and butane through defective pipelines and sewers. This can occur, for example, when methane and hydrogen sulphide are present in nearby installations, or from any processes involving battery charging, which can give rise to hydrogen. Propane and butane are potentially very dangerous as, due to their density, they may find the lowest point in the excavation and form an explosive atmosphere.

Access and Preventing Falls of People A safe means of access and egress must be provided for all excavations. Ladders provide the main method for access and egress and care should be taken to see they are in good condition. They must be suitably secured to prevent undue movement and extend above the excavation to give the necessary height required for a safe handhold. To allow for adequate means of escape in an emergency, it is considered that one ladder every 15 metres is an average to work to, but more may be required depending upon the number of workers and the potential risk, e.g. where there might be a possibility of flooding from a rising water table. Handrails must be provided around every accessible part where a person is liable to fall. Gangways across excavations should have guardrails and toe boards. If excavations are not completed during a day’s work and need to be left open, consideration has to be given to lighting to give warning of the potential hazards and for illuminating working areas. For illumination of the actual place where work is taking place, lighting towers will normally be used. Consideration must be given to lighting inside the excavation to prevent slips, trips and falls. The conditions encountered will affect the choice of system which could be 110V, low

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voltage or battery. Smaller, battery operated personal lights for individual workers may also be considered.

Buildings and Machinery It is vitally important to ensure, before excavations are carried out, that the stability of buildings adjacent to the work area will not be adversely affected by the excavation. Consideration may have to be given to constructing temporary supports for buildings while work is being carried out. Machinery in the area of excavation should be set well back from where digging is taking place to prevent:

The possibility of its falling into the excavation.

Vibration from machinery undermining the sides of the excavation.

Flooding The flooding of excavations by water, for example, melting snow, heavy rain, tidal waters, ground water accumulation or from surface and underground streams, is a common accident situation and may occur naturally or as a result of an unexpected encounter with a large water pipe or drain. Dealing with a burst pipe is generally fairly straightforward, after a suitable valve has been located and closed. Dealing with the problem of natural water may not be so easy as water can flow into the excavation, depending on the permeability of the ground, and the level of the water table (ground water). There are various means of controlling flooding, including sloping of excavations to sumps at low points where drainage pumps can be used. Increased exit points, permit systems and baffles can help to improve the safety for those who do need to enter excavations where flooding is possible. The disposal of such water should be discussed with the appropriate environmental agencies, as run off from agricultural land or nearby contaminated land may cause environmental damage. Great care must be exercised if flooding occurs near buildings as this may undermine foundations.

Electricity The Area Electricity Company should be consulted before any work commences and a safe system of work devised and implemented. There must be direct supervision of this by a competent person. The most practical step that can be taken to prevent danger from any live electrical cable or apparatus if it cannot be re-routed is the placing of adequate and suitable barriers. If access is possible only from one side then a barrier on this side only will suffice but if the overhead line crosses the site then barriers will be required on both sides of it. If there is danger to men carrying metal scaffold poles, ladders or other conducting objects, then the barrier should exclude both men and mobile plant (see the figure that follows).

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The Placing of Barriers If mobile cranes or excavators are used, the minimum distance from the ground level barrier to the line should be 6 metres plus the length of the jib or boom. It should be noted that the electricity supply companies may advise a greater distance, depending on the voltage of the overhead line and the lateral swing of conductors in high winds. Requirements include that no work should take place:

Within 9m of overhead power lines on wood, concrete or steel poles.

Within 15m of overhead power lines on steel towers.

Or until the appropriate electricity company is consulted for suitable advice.

Such distances are measured horizontally at ground level directly below the outermost conductor. The above also applies to overhead power systems for railways and trams.

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Suitable Barriers for Mobile Plant Any ground level barriers should consist of either:

A stout post and rail fence, or

A tension wire fence earthed at both ends, having flags on the wire, the fence being earthed in consultation with the electrical utility, or

Large steel drums (for example 200 litre oil drums) filled with rubble or concrete and placed at frequent intervals, or

An earth bank not less than 1 metre high and marked by posts to stop vehicles, or

Substantial timber baulks to act as wheel stops.

Fences, posts, oil drums, etc. should be made as distinctive as possible by being painted with red and white stripes, alternate red and white plastic warning flags or alternatively hazard bunting should be used on wire fences (as shown in the previous figure). There should be a general rule prohibiting the storage of materials in the area between the overhead lines and the ground level barriers. Precautions are necessary even though work in the vicinity of the line may be of short duration. Before doing any work on site:

Consult the local electricity supply company. A Code of Practice of ‘do’s and don’ts’ is available from most companies. They will usually arrange a site meeting and advise on heights, distances and other precautions.

Assume all overhead lines and cables are live unless advised otherwise by the electrical supply company.

All work should be under the direct supervision of a responsible person appointed by the employer, familiar with the hazards likely to be encountered.

Ensure safety precautions are observed.

All plant, cranes and excavators may be modified with suitable physical restraints to limit operations where applicable.

Additional care may become necessary as work proceeds because of reduced clearances.

Electronic proximity warning devices may be fitted on crane jibs, etc.

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Advance warning sign

Note: If any work takes place after dark notices and cross bar should be illuminated

Between 3-6 m

Height to be specified by Electricity Board

Traffic Passing Beneath Overhead Power Lines With relation to the diagram above, the minimum distance between any barrier and the overhead power lines is recommended but not prescribed. Construction recommendations are 6 and 12 metres between the barrier and the power lines, while forestry and arboriculture recommendations are 9 metres for wooden poles and 15 metres for metal towers. The most specific recommendation is for consultation with the electricity supply company before works commences. Where it is necessary to work beneath live overhead cables additional precautions will be required to prevent the upward movement of ladders, scaffold poles, crane jibs, excavator buckets and to follow a specific passageway. Specific advice should be sought from the electrical supply company or from the Health and Safety Executive.

Underground Underground power cables exist at various voltages from 240 V to 400,000 V and are the cause of many accidents every year. The majority of underground cable accidents result in burns and a few fatalities. Most overhead line accidents result in electrocutions or electric shock and a large number of fatalities. Permits-To-Work Written procedures such as permits-to-work may be appropriate as they enhance safety by setting down the agreed safe working procedure in writing. They also ensure that the work is planned before it commences. Where the system isolation is undertaken by someone other than the person intended to carry out the work, it is often useful for a permit-to-work procedure to be adopted. This confirms the system isolation and provides other relevant information. The completion and issue of such a document therefore acts as a reminder that the necessary precautions to achieve electrical safety have been implemented, as well as providing a means of recording plant held out of service.

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Where such a system of work is rigorously followed, an accident is unlikely to occur. Many accidents do, however, happen when work is attempted on what is intended to be a deenergised system but, due to some oversight, is still live. Invariably these arise due to a failure to follow strictly all the above-mentioned requirements for a safe system of work. There is a need for management to formulate a clear policy concerning work on electrical systems for which they have responsibility. A permit can only be issued by a person who is competent at knowing what dangers can arise, what work has to be done, what is required to make the work area safe, and knows the competence of the person who will carry out the work. He or she will also know whether that person needs to be accompanied in the interests of safety. The permit-to-work, as seen in the next figure, should be clearly written to avoid confusion and should contain the following information:

The identity of the person supervising the work and to whom the permit is issued.

Sufficient detail to accurately identify the equipment made dead and its location; a diagram will usually ensure that these points are precisely described.

The location of the points of isolation.

The location of temporary earth connections.

The location of warning notices and safety locks.

A detailed description of the work to be carried out.

An account of other hazards that might be encountered together with any detail necessary to identify them.

Further precautions to be taken during the course of the work.

Once the permit has been accepted and signed by the work supervisor, he or she takes full responsibility for his or her own safety and the safety of those under their control. The work supervisor should retain the document until the work is completed. Upon completion, he or she must ensure that the entire workforce is withdrawn, together with their tools and equipment, and instructed not to return. Any temporary earth connections must also be removed. The equipment should not be re-energised until the permit is returned to the person who issued it for cancellation. If it is necessary to alter the work schedule, the existing permit must be cancelled and a new one issued. Avoiding Danger from Underground Services Underground cables are particularly hazardous because they are concealed, frequently close to the surface, sometimes occur in unexpected locations, and are often poorly protected. Damage to cables usually occurs during excavation work and is caused by the crushing or penetrating effects of hand or machine tools such as pneumatic drills and mechanical excavators. A tool may penetrate the sheath of a cable and the cable insulation or crush the cable and cause contact between the conductors or between the sheathing and one of the conductors. Damage to live cables often results in arcing currents with associated explosive effects, fire and flames that usually cause severe, potentially fatal burns to the hands, face and torso. Direct electric shock is rare.

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As underground cables are widespread, if excavation work is to be undertaken it should be assumed that cables are present and live until it is proved otherwise. A safe system of work incorporating the following precautions should be used:

Cable location plans.

Cable location devices.

Safe digging practices.

Trained personnel.

Use of Cable Location Plans Before work commences, cable plans or other information should be sought in an attempt to locate the position of all cables in the area in which the excavation is to take place. Where available, the information should be obtained from the owners of the cables, such as the local electricity company, the local authority and private landowners. Plans are frequently inaccurate for a number of reasons, such as repositioning of the cable without the knowledge of the owner, re-grading of ground which alters the depth of the cable, removal of the reference points originally used to locate the position of the cable, change of street layouts, and snaking of cables in trenches. Above-ground installations such as street lighting, illuminated signs, substations and evidence of backfilled trenches that may house underground cables can also be used. Most plans will give useful information on the location, number and configuration of cables and will help in the use of cable detectors. However, they cannot be relied upon to give precise information. It will also be useful to look at the ground for information as to where cables may be situated, as there will be visual signs, such as inspection covers and back-filled trenches. Cable Locating Devices The location of cables shown on plans should be checked as accurately as possible using a cable locating device. Where no plans have been obtained, the use of the cable detector is additionally important. As cables are located with the device, their routes should be marked on the surface of the ground with waterproof crayon, chalk, paint or wooden pegs as appropriate. Various cable locating devices are available, the main categories being:

Hum detector: detects the magnetic field radiated by live cables that have a current flowing through them. The disadvantage is that cables with little or no current flowing will not be detected, for example, street lights.

Radio frequency detector: receives the low-frequency radio signals that may be picked up and re-emitted by cables. A disadvantage is that objects other than cables may re-radiate the signal and be detected. Results may also vary depending on locality and length of cable.

Transmitter-receiver detector: a signal is induced into a cable by a transmitter which is connected either to the cable or placed close to it. The receiver detects the signal, thereby locating the route of the cable. These devices require more skill to operate and also rely upon knowledge of some part of the cable in order that a connection point for the transmitter may be identified.

Metal detectors: these will locate flat metal covers and joint boxes but may not detect round cables. However, they can be useful in the location of possible points of connection for transmitters as above.

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Ground penetrating radar.

The main disadvantage with cable detectors is that they may be unable to distinguish between a number of cables in close proximity and may register them as one cable. If two cables are located one above the other, the upper one may be located but not the lower one. It cannot be assumed that all cables have been successfully identified and therefore use of cable locating devices cannot be relied upon in isolation. Locating devices should only be used by trained operators, within the manufacturer's guidelines, and should be maintained in good working order. Safe Digging Practice Once the location of cables has been ascertained using plans and detectors, the routes should be confirmed by digging trial holes that should expose the cables. Hand tools should be used and particular care should be taken above or close to the route of the cable. It is preferable that excavations should be alongside rather than above the cable and that final exposure should be by horizontal digging which is easier to control. Incorrectly used hand tools cause many accidents every year. Accidents may be minimised by the use of spades and shovels rather than other tools such as picks, avoiding spiking or throwing tools into the ground, or by using compressed air tools (such as air-knives) that can expose cables safely. Hand-held power tools and mechanical excavators are a major source of danger and should not be used too close to underground cables. Certain precautions should be taken once cables have been exposed. In particular, cables:

With spans of more than a metre should be supported.

Should not be used as hand or footholds.

Should not be moved unless absolutely necessary.

Should be reinstated with advice from the owner.

If cable locations are altered during the work, the cable owner should be notified before backfilling of trenches in order that location plans may be amended. Trained Personnel All personnel who are involved in excavation work where underground cables may be present should be adequately trained in the dangers and the precautions that should be taken. Training should include details on how the hazards occur, types of cables, depths of laying cables, use of plans and location devices, and action to be taken in the event of cable damage. If a cable is damaged, all work in the vicinity of the damage should stop. Temporary barriers and warning notices should be erected to keep people away from the danger and the cable owner requested to repair, or otherwise make safe, the damage before work is allowed to resume.

Machinery/ Vehicles Minimise Reversing A high number of fatal accidents are due to reversing vehicles. It is essential to minimise reversing wherever possible. One-Way Systems One method by which the need to reverse can be minimised is by the use of one-way systems which are clearly marked.

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Training It should never be assumed that people will automatically be aware of the hazards around them and understand the necessary preventative and protective measures in place. It is important, therefore, that all persons are given appropriate information to enable them to move around the workplace in safety. Instruction should be given as to general conduct, such as not running or playing games, as well as in respect of particular hazards. Part of this will be in the form of signs, markings and notices, but additional information may also be necessary, for example, about keeping to designated walkways, being aware of particular hazards, such as temporary work going on overhead, etc. Visitors to premises may need special instruction prior to entry. In certain circumstances, people need to be specifically trained in how they should move around in certain circumstances, even if just by being shown. This could include, for example, correct procedures for climbing ladders, walking through certain types of door where they use one-way systems, moving around while carrying loads, wearing appropriate clothing, etc.

Collapse of Structures Survey Prior to demolition taking place, a safe system of work must be established. The system will be determined by a pre-demolition survey – including perusal of the original building plans, if they are still in existence – undertaken by a competent person. The use of a demolition hazard checklist is recommended. This survey should identify:

The nature and method of construction of the building. It is important to determine the structural condition, as deterioration may impose restrictions on the demolition method. There may be seriously weakened structural members or connections due to corrosive atmospheres, arising from the process used on the premises, or the structure may be dilapidated through exposure to the elements or vandalism.

The arrangement of buildings adjacent to that for demolition, and the condition of this adjoining property and any need to make adjacent premises weather-tight.

The location of underground services, e.g. water mains, electricity cables, gas pipes, drains, sewers, telephone cables, and details of their removal or making safe.

The previous use of premises, e.g. for the storage of flammable substances, and details of methods for dealing with hazardous substances which may have been retained or deposited as residue in process machinery, pipework or storage. This will also include the presence of storage tanks below and above ground, and the nature of their contents.

Details of methods to establish the presence of substances that may be hazardous to health, the methods to be used for their disposal and any necessary protective equipment.

The need for any temporary works or shoring, either to adjacent premises or within the property to be demolished, to allow the design, fabrication and installation of the necessary temporary work in sufficient time.

The presence of dangerous substances such as asbestos lagging.

The method of bonding of the main load-bearing walls.

The presence of cantilevered structures, their form of construction and the nature of the danger.

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The presence of basements, cellars, vaults or other spaces affecting the structure of adjoining properties.

The potentially dangerous effects of removing superstructure stabilising loads from an old basement or vault retaining walls.

The sequence and method of demolition or dismantling of the building or structure, with details of personnel access, working platforms and machinery requirement.

Specific details of any pre-weakening on structures that are to be pulled down or demolished with explosives.

Arrangements for the protection of personnel and the public and the exclusion of unauthorised persons.

Details of temporary services available or required for the contractor’s use.

Arrangements for the control of site transport used for the removal of demolition debris.

Method Statements The proposals relating to the pre-demolition survey and preferred method of working can be incorporated into a demolition method statement. This sets out the sequence of work and the methods to be employed for each type of work. A method statement is necessary for all demolition work. The method statement is derived from a risk assessment made by the contractor. The method statement should:

Be drawn up before work starts.

Be communicated to all involved.

Identify the work procedure, associated problems and their solutions.

Be easy to understand.

Be agreed by all and known to all (of whatever level).

Form a reference for site supervision.

The demolition method statement should include:

Name and address of demolition contractor and site.

Sequence and method of demolition.

Details of personnel access, working platforms and machinery requirements.

Details of any pre-weakening of structures which are to be pulled down or demolished using explosives, and temporary propping required.

Arrangements for the protection of personnel and the public, and the exclusion of unauthorised people from the work area.

Site security including the provision of, for example, suitable fencing and/or barriers; controlling of spectators and/or site visitors; use of exclusion zones; and containment of demolition materials.

Details of the removal or isolation of electrical, gas and other services.

Details of temporary services required and welfare services provided.

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Arrangements for the disposal of waste.

Details of environmental considerations, such as dust, noise, pollution of water, contaminated ground.

Details of controls covering substances hazardous to health and flammable substances, e.g. asbestos, LPG, compressed gases, and any permit-to-work system.

Arrangements for the control and co-ordination of the site, e.g. transport, contractors, storage.

Training requirements and competencies of personnel involved in the demolition process.

Identification of people with special responsibilities for the co-ordination and control of safety and emergency procedures and arrangements.

Demolition Technique Piecemeal •

Masonry and Brick Buildings Demolition by hand-held tools, sometimes as a preliminary to using other methods, should be carried out, where practicable, in the reverse order to the original construction sequence. Lifting appliances may be necessary to hold larger structural members during cutting and for lowering several structural members and other debris. Chutes may be used to discharge debris into a vehicle or hopper. Parts of floors may be removed to permit the fall of debris, but when such floor openings are not in use for this purpose and people are likely to need access, the openings should be covered or protected by guardrails and toeboards. Before the removal of floors and any other stripping of the interior of the building, for example for salvage, a competent person should ensure that the stability of the remaining structure is maintained, including any lateral or diaphragm support for large panels of wall, particularly while they continue to support loads from above.

•

Steel Structures Where practicable the sequence of demolition for a steel-framed building by piecemeal methods should also be in the reverse of the construction sequence. All non-structural material should normally be removed before the structural frame is dismantled. Each main structural member, including any roof truss, should be supported by a crane or by temporary props while the ends are unbolted or cut with a gas torch. Anyone working near the member should be made aware that when the member is cut it may suddenly vibrate or spring due to the removal of the load-restraining connections. Each main structural member or truss should be lowered to ground level. Timber joists that span between the beams of steel-framed buildings may be severed with a chain saw. Where the timber joists are allowed to drop to a lower level, the area below should be sealed to prevent anyone entering.

Deliberate Controlled Collapse This is an economic method of demolition that relies upon removing key structural members so the remaining structure collapses under its own weight. There are inherent hazards with this method:

The structure may collapse to a greater extent than expected.

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The planned collapse may only partially take place and a very insecure and hazardous structure remain.

Considerable amounts of debris may be projected over a wider area than expected, with the possibility of hitting unprotected persons.

The collapsed structure may leave a difficult and dangerous pile of debris to be removed.

Another method of creating a deliberate collapse is by attaching a wire to the structure and pulling away the main supports using a heavy tracked vehicle or a winch to provide the motive power. Apart from the problems noted above, other problems arising are:

Overstressing of the wire rope.

Breaking of the wire rope and the resulting whiplash.

Overturning of the winch or tracked vehicle.

Inadequate power to complete the operation once it has begun.

Where deliberate collapses are engineered it is recommended that no one should be nearer to the building than twice the height of its highest part.

Falling Objects Exclusion Zones A considerable amount of demolition is carried out by undermining a structure and causing collapse of material. The amount of material will vary but irrespective of the quantities involved, one general principle that emerges is the need to isolate the demolition area so that potential hazards may be confined. This precaution will also help to exclude from the site persons not directly involved in the work. The methods used will vary depending on the nature of the demolition. Ideally some form of high fencing or board about 2.5 metres high should be erected around the site where the public could be at risk. In areas restricted from the public, rope and spigot barriers decked overall with plastic strips are satisfactory. Warning notices must be set up around the barriers being used. Where space is limited, scaffolding will have to be erected around the site, and protective screens and fans constructed to reduce the possibility of debris falling onto pedestrians. Broken glass from windows can be a hazard to workers, but if window panes can be removed without indiscriminate breakage, this hazard can be reduced. Window and door frames should be left in a structure until the last possible moment as they can be used to advantage by providing structural support for a building while demolition is taking place. Boarding over open windows and doorways will help to make the building more secure against intruders. Warning notices should be erected at doorways, especially if floors have been removed.

Crash Decks, Nets, Fans, Sheeting People should be kept away from where demolition is being undertaken by the effective application of exclusion zones to all demolition operations, to include deliberate dropping, the potential for dropping of materials, or inadvertent falls of dislodged material. Before and during demolition operations, site managers should ensure that all site personnel have a safe place of work and a safe access to their place of work including access by roads, gangways, passageways, passenger hoists, staircases, ladders. Scaffolds, permanent access stairs or catwalks used by demolition personnel should be maintained in a safe condition, for as long as possible.

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The planning, provision and maintenance of access routes and working places should include the following:

Freedom from obstructions, including tripping hazards such as debris, materials and tools.

Projecting nails from timbers (which should be removed or hammered flat).

Walkways and working platforms that are not overloaded.

Pedestrian routes that are segregated from routes used by vehicles and plant.

Erection of adequate barriers or other edge protection, to prevent falls from the open edges of roofs, buildings, gangways, staircases and lift shafts.

Holes and openings that are securely fenced off or provided with adequate, fixed, clearly marked and properly secured covers.

Adequate artificial lighting should be provided when work is carried out in the absence of sufficient natural light.

When the risk assessment shows that the only reasonable method is to work at an open edge, such as when not using remote machine methods, a safe, independent working platform or an anchored fall restraint or fall arrest equipment should be used. Adequate protection of workers, contractors and members of the public from any falling material is necessary, e.g. walkways adequately lit and made of fully sheeted scaffold with either monoflex debris netting or reinforced plastic sheeting, or other temporary structures. Such structures should be designed to take account of the loads, including wind loads, imposed when sheeting and/or netting material are used. Fire exit routes should not be obstructed and possibly use fire-retardant sheeting and netting. Where appropriate, windows should be boarded up to prevent materials falling or being ejected from the apertures. Protective gantries, fans, crash decks and/or coverings should be erected to protect areas of public access where falling loads or equipment are possible. Provision of the correct hard hats, boots, clothing, goggles, etc. is required to maintain a safe person strategy during the demolition process. Lifting loads over areas of public access should be avoided where possible. Where it cannot be avoided, temporary closure of the highway and the provision of safe alternative pedestrian routes is required. It may be necessary to restrict or prohibit access beneath the demolition work at times when safety cannot be guaranteed. Occupants should not remain in a building undergoing major demolition work. If demolition work is carried out to a building a part of which is to remain occupied, a risk assessment should be carried out as a basis for a safe system of work. The assessment should include provision for the occupied part requiring evacuation and for effecting such an evacuation safely. Any risk assessment should include the possibility of materials acting as a projectile. Before demolition begins, it is necessary to determine where temporary support will be needed and this should be clearly stated in the method statement for demolition. No part of the structure should be so overloaded that any part of it becomes unstable during demolition work. Protective fans, crash decks and gantries are temporary structures that should be of adequate strength to safely support unplanned falls of material, including accidental falls of tools and materials. If necessary, they should be waterproofed to protect persons below from drips and should not be used for storage or for access. Access ways and working places should not be used as catchment areas.

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Fan Protection Falling objects are a general problem on construction sites. This may involve such materials and objects falling into excavations from scaffolding, hoists, hoist towers, lifting appliances, or MEWPS, roofs, and between floors in buildings. Objects falling from a height are clearly capable of causing considerable damage to both people and other materials that they hit. The objects themselves may be: loose structural material such as tiles, bricks and timbers; waste materials such as stone chippings or off cuts of wood; or equipment or tools which are dropped. Circumstances that contribute to the likelihood of falling materials include the following:

Deterioration of structures causing crumbling brickwork or loose tiles.

Bad storage of materials, for example, at the edges of scaffold platforms, or in unstable stacks.

Poor housekeeping leading to accumulations of waste and loose materials.

Gaps in platform surfaces or between access platforms and walls.

Open, unprotected edges.

Incorrect methods of getting materials, equipment or tools from ground level to the working area.

Incorrect methods of getting materials down to ground level, for example, being thrown off instead of being lowered in a bucket or down an ‘elephant’s trunk’ to a skip.

The first objective as regards falling objects must be to prevent materials from falling in the first place, from whatever source, including roofs, scaffolds, MEWPs, etc. Possible control measures for falling objects may include:

Not stacking materials near edges, and particularly unprotected edges.

Close boarding of working platforms to minimise the gaps between scaffold boards, or placing sheeting over the boards so that material cannot fall through.

Using hoists to convey materials up to a height, rather than carrying them.

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Providing safe means of lowering materials, such as hoists or chutes, rather than having them carried down or, worse, thrown down.

Where these actions are impractical or will not necessarily eliminate the risk, measures to protect people underneath from being hit by falling materials must be introduced. These could include the construction of covered walkways, for instance, ‘tunnels’ formed by closely boarded scaffold planks, or sheeting through which pedestrians can walk.

Slips, Trips and Falls People walking around construction sites, including employees, contractors and visitors, are very often distracted. They are often unaware of the possible hazards and may well not notice things, such as large obstructions or steps, or holes in the ground. It would be impossible to guarantee that people would walk around concentrating all the time on potential hazards. There may be many groups passing the site, such as schoolchildren, hospital visitors or shoppers. Partially occupied housing sites and parking areas would also present problems. As a result, therefore, it is important to adopt appropriate control measures to reduce the risks associated with hazards. These measures will include engineering, procedural and behavioural controls, based on systematic risk assessment, along with the duties and responsibilities of certain personnel. Identification of the hazards faced by such people and suitable and sufficient risk assessments needs to take account of the following factors: •

The natural patterns of movement in and around the workplace, and in the vicinity of the workplace.

•

Patterns of movement outside of those which are natural, whether authorised or not, and which may be reasonably predicted, such as short cuts taken, unusual numbers of people at certain times, etc.

•

The particular needs of certain groups of people, such as visually or hearing impaired people, people in wheelchairs, pregnant women, elderly people and children.

•

The needs of persons not normally on the premises, including temporary workers, contractors and visitors, and even trespassers.

•

The impact of maintenance strategies and processes – for example, in repairing road surfaces, charging of electrical batteries, storage of hazardous materials, etc.

•

The effectiveness, in practice, of existing measures and systems of work in providing adequate protection for pedestrians.

Control measures for slips, trips and falls, taking into account such risk assessments, could include: considering the floors and surfaces of traffic routes; considering traffic and pedestrian routes; handrails; designated walkways; temporary barriers; fencing; signs; hazard warnings; PPE and training. We will now consider these issues in more detail. Floors, including suspended walkways, must be of solid construction, and of appropriate strength and stability to cope with the load placed on them and the traffic passing over them. They should not be overloaded. The surfaces of pedestrian and traffic route floors should be free from any holes, excessive slopes, unevenness or unsecured coverings which may be likely to cause a person to slip, trip or fall, or to drop or lose control of anything being lifted or carried. Ramps should be provided where necessary for disabled access. Holes, bumps or broken or uneven areas resulting from

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damage or wear must be repaired at the earliest opportunity, and there should be procedures in place to ensure that such conditions are reported in good time. Floor surfaces, roadways and temporary access routes must be adequately drained, and effective drainage should be provided where a surface is liable to get wet. Floors that are likely to get wet or be subject to spillages should be of a type that does not become unduly slippery. A slip-resistant coating should be applied when necessary. Floors near to machinery, which could cause injury if anyone were to fall against it, should be slip resistant and kept free from slippery substances or loose materials. Any spillages or rubbish left lying around should be cleaned up immediately. Arrangements should be made to minimise risk from mud, snow and ice on walkways. This may involve maintaining them in a good condition, gritting, snow clearing and closure of some routes, particularly in respect of outside stairs, ladders and walkways on roofs. There should be sufficient traffic routes on site, of sufficient width and headroom, to allow people to circulate safely and without difficulty. Any slopes or gradients should be no steeper than are necessary. All routes should be kept clear of obstructions that may present a hazard or impede access. Secure handrails must be provided for moderate or steep slopes, and on ramps used by people with disabilities. There should be handrails on at least one side of every staircase, and where the width of the staircase exceeds one metre, a handrail is required on both sides. In areas where pedestrians have to pass possible hazards, such as machinery, stacks of materials and overhead workings, their movement should be confined to designated walkways. These are areas which are specially protected from hazards, for example, by nets, or covered to protect from falling objects, and within which pedestrians should be reasonably safe from harm. They should be clearly designated by signs, notices and markings indicating routes, hazards and warnings and speed limits. These would define the limits of the safe area. Safe crossing places that are clearly marked should be used. Possible blind spots should be fitted with mirrors to improve visibility. Increased lighting should be installed, allied to an appropriate speed limit. Physical barriers of sufficient strength and stability in the form of fencing and other types of guards and cones should provide protection from hazards to the sides, and from above and below. Handrails should be provided as necessary. Special rules ensuring that designated walkways are kept clear of any obstacles, debris and litter must be in place, and walkways should be checked to ensure compliance. Temporary barriers, cones and warning tape may also need to be erected to prevent access to certain areas. This includes: broken floor surfaces, wet or slippery floors during cleaning and around temporary obstacles and welfare facilities, etc. Fencing should be provided on any open walkways where there is a risk of falling. This includes routes over excavations, suspended walkways and bridges. Perimeter fences should normally be two metres high. Clearly visible, conspicuous and easily understood signs, markings and notices must be provided to ensure that pedestrians are aware of any hazards and what they should do to avoid them. Hazard warning markings, yellow diagonal stripes on a black background, should be used on any object likely to present an unforeseen hazard. This can be by means of tape, paint or by the use of covers. Examples of hazards include: the edges of steps, overhead obstructions and trailing cables or pipes temporarily laid across a floor. Cordless tools might be considered to remove hazards associated with trailing cables. In addition, hazard markings on floors

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should indicate areas to avoid, such as traffic routes used by vehicles, and should demarcate the edges of safe walkways. The positioning of such signs is important and they should be conspicuous at junctions, crossings and along pedestrian routes. Such signs should be maintained to a high standard, especially in conditions of inclement weather, and inspected on a regular basis. It may be necessary for employees, contractors and visitors in a particular area to have the same or similar PPE as people working in that area. Examples include: •

Non-slip footwear where chemicals are used.

•

Hard hats, Wellingtons or suitable boots with toe caps and sole plates on a construction site.

Safety signs will indicate where such requirements are mandatory and they will apply to all people entering such areas, even if they are just visiting or passing through. Hard hats are to be worn by anybody who might be struck by falling materials or where people might hit their heads. Examples include material falling from a scaffolding platform and material falling from a crane and goods hoist. Similarly, appropriate footwear should have steel toecaps and sole plates to prevent puncture wounds and injuries by sharp objects. People working on site or visiting will not automatically be aware of the hazards around them or understand the necessary preventative and protective measures in place. It is important, therefore, that all persons on site are given appropriate information to enable them to move around the workplace in safety. Instruction should be given as to general conduct, such as not running or playing games, as well as in respect of particular hazards. Part of this will be in the form of signs, markings and notices, but additional information may also be necessary. For example, attention may have to be drawn to the need to keep to designated walkways and to be aware of particular hazards, such as temporary work going on overhead. Visitors to premises may need special instruction prior to entry.

Manual Handling Control measures for risks from manual handling activities include:

Avoiding the hazard, which will remove the risk completely.

Re-designing the task to include, for example, sequencing of tasks, changing the work routine or using teams.

Modifying the load, by taking into account matters the weight and size, and other practical issues that would make the load easier to handle.

Reorganising the work environment, by considering things like workstation design and floor conditions.

Personal considerations, such as making allowance for employees with temporary or permanent health problems.

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BSC Level 6 International Diploma | Unit 1 Element 1B: Applied Health and Safety Management


Title

Page

Working at Height

MAIN HAZARDS AND RISKS ASSOCIATED WITH WORKING AT HEIGHT............................................................ 3 FALLING FROM SCAFFOLDING AND LADDERS ................................................................................................................... 3 FALLING FROM ROOF EDGES ...................................................................................................................................... 3 FAILURE OF EQUIPMENT ........................................................................................................................................... 4 FALLING THROUGH FRAGILE SURFACES ......................................................................................................................... 4 BEING HIT BY FALLING OBJECTS ................................................................................................................................. 4 CONTROLLING THE RISKS FROM WORKING AT HEIGHT ................................................................................... 5 HIERARCHY OF CONTROL.......................................................................................................................................... 5 ORGANISATIONAL ARRANGEMENTS .............................................................................................................................. 6


BSC Level 6 Diploma | Unit 1 Element 1B: Applied Health and Safety Management Study Unit 1B12 | Working at Height Learning Outcomes When you have worked through this Study Unit, you will be able to:

1.B.12.1 Describe the main hazards associated with working at height and explain how they may cause harm 1.B.12.2 Determine, implement, evaluate and maintain measures for controlling risks from working at height

Unit 9:

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Main Hazards and Risks Associated with Working at Height Working at height is the single biggest cause of workplace deaths and one of the main causes of major injury. Interestingly more than half of serious fall injuries, such as fractured skulls, broken bones and severe cuts, are caused by falling from below head height. The most frequent causes of accidental death and injury during working at height activities are discussed below.

Falling from Scaffolding and Ladders One of the major hazards, particularly in construction and demolition, is that a great proportion of work is done at heights. The danger of falls of people and materials affects not only those working at heights, but sometimes to a greater degree, those underneath. Falls are the largest cause of accidental death in the construction industry. Accidents involving falls could be prevented if the job is planned properly, if safe systems of work are adhered to and if the right equipment is used. Other dangers include:

Bad storage of materials.

Insufficient guarding or edge protection.

Unsatisfactory access or egress.

Incorrect method of getting equipment or tools from ground level to the working platform.

Any company that has persons working at heights should, at the very least, provide a method statement outlining the nature of the operations and precautions to be taken. Many of the reported falls from height incidents in the UK involve ladders and step ladders. Many of these injuries are caused by inappropriate or incorrect use of the equipment. Ladders are so widely used that their dangers are often completely overlooked. They are frequently used in unsuitable locations where they form inappropriate working places, and they are often incorrectly used and poorly maintained. Incorrect selection of equipment, erection, securing and use are the main problems. Scaffolding provides a much safer working platform but can also suffer from incorrect design and erection which can lead, in the worst case, to scaffold collapse, or at least incomplete construction which can allow falls of persons or materials.

Falling from Roof Edges People fall because access to and from the workplace is inadequate, or the workplace itself is not safe. The high-risk occupations where falls are of major concern include: roof work, steel erecting; formwork, such as shuttering and concreting; steel fixing and demolition. Accidents involving workers falling from roof edges (the leading edge) are often due to one-off or short duration tasks where assessments of risks have not been undertaken and therefore the risk of falling from the roof edges have not been considered. In some situations, especially with experienced workers there is a faulty perception of the real level of risk due to complacency. Short cuts are another common reason for workers falling from roof edges where the cost and inconvenience of erecting roof edge barriers have been considered prohibitive and time consuming either by the workers or by their managers.

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Often though, work at the leading edge is unavoidable due to the nature of the work (removing and replacing roofing sheets) and the position of the structure, making the use of a working platform impractical. Where this is the case, the work requires carefully planned safe systems of work including measures to mitigate the distance and consequences of a fall.

Failure of Equipment Many accidents involving falls could have been prevented if the right equipment had been provided and properly used. Equipment fails when it has been selected for a job which it is not intended. The result may cause the equipment to collapse, fall over or not support the worker or materials adequately posing a risk to workers and third parties. The installation of particular types of work equipment such as scaffold must be constructed by a competent person to ensure that there are no risks to safety. Equipment that is stored incorrectly may show rapid signs of deterioration which without regular maintenance could be the cause of an accident. All equipment must be used by trained persons.

Falling through Fragile Surfaces A fragile surface is a surface which would be liable to fail if any reasonably foreseeable loading were to be applied to it. This would include all sheeted roofs especially asbestos cement, fibreglass and plastic sheets (which become more fragile with age). Other examples of fragile roofs include steel sheets that rust over time, skylights and roof windows and indeed any roof that is poorly repaired. Roof openings that are not covered, protected or clearly indicated are also the cause of many falls. Fragile surfaces are not designed to support a person’s weight and any work carried out on top of a fragile surface is likely to lead to a fall unless extreme care is taken. All work on fragile roof should be carried from beneath wherever practicable. A common cause of falling through the fragile roof is the lack of full risk assessment, which would include a calculation of load capacity. A good rule of thumb here is that if the surface was not specifically designed to take the weight of people then it should be treated as a fragile surface.

Being hit by Falling Objects Another common hazard associated with working at height is that of objects falling from a place above their head that are not correctly secured. Often the objects will fall due to poor storage and containment of tools or materials from a working platform at height. Tools and materials are occasionally are dropped by accident from the hands or they will fall from the tool belt of the worker and unfortunately the unsafe practice of “bombing” still takes place on many construction sites (throwing objects to the ground from a height). It should be noted that it is not only workers who are at risk from falling objects. Members of the public are often nearby the work being undertaken and if safeguards have not been taken to prevent falling objects then they are at risk of serious injury also.

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Controlling the Risks from Working at Height Hierarchy of Control The basic principles of control regarding working at height are to be considered as a hierarchy, as follows:

Avoid work to height where possible, for example, by planning work and working from the ground.

Use work equipment or other measures to prevent falls where work at height cannot be avoided.

Where the risk of a fall cannot be eliminated, use work equipment or other measures to minimise the distance and consequences of a fall, should one occur, taking into account the duration and environment in which the work is to be completed.

Avoid Work at Height The first consideration should always be to ask the question “Is it possible for the work to be done from ground level”. Quite often a little thought and effort at this stage will provide other ways of performing the task such that work at height is simply not required. Think about whether it is possible to design out the need to work at height, e.g. could new or replacement services, such as pipes or cables, be put at ground level? Long handled tools or other equipment can sometimes be used to carry out a task from ground level, e.g. a long-handled brush or roller for painting and water fed poles with brushes for window cleaning. In construction it is often possible to erect guard rails onto the steelwork at ground level and then crane the steel and the guard rails into position. As explained, if work at height cannot be avoided, steps must be taken to prevent the risk of falling.

Prevent Falls Prevention could be achieved by:

Using an existing place of work, for example, a flat roof with permanent edge protection, to gain access. This is a place that is already safe.

Using collective work equipment, such as: guardrails, MEWPs, scissor lifts, cradles, tower scaffolds and independent scaffolds.

Using personal work equipment, for example, a work restraint system such as harness and lanyard that prevents people getting to a place where they might fall.

Minimise Consequences If measures cannot be put in place to prevent falls, the employer must introduce measures to minimise the distance and/or the consequences of a fall. Safety nets and soft landing systems (polystyrene-filled bags, air bags etc) can be used as leading edge protection to mitigate the consequences and distance of a fall. They are not a substitute for the use of fall prevention measures but can be used in conjunction with them if the risk of a fall cannot be eliminated.

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Safety nets are an energy absorbing system, which should only be installed by trained and competent people. Before gaining access to height you should decide whether nets can be installed at ground level. Nets should be positioned as close as possible to the working level to minimise the height of a fall. As a last resort safety harnesses may be used as a fall arrest system. One of the main problems associated with this type of system is that it only protects the wearer (as with all PPE) if it is worn correctly and if the lanyard is correctly secured to a suitable anchor point. The use of this type of system requires a high degree of training, competence and supervision. The free fall distance must be kept to a minimum as there is a high risk of injury from the impact loading on the body or from the ‘pendulum effect’ – striking the structure as they are left to swing. To reduce the risk of injury, a fall arrest system should always contain energy absorption. Consideration must also be given to how to rescue anyone who does fall. It is not appropriate to rely on the emergency services as they might not arrive in time or might not have the necessary equipment to carry out a rescue. When planning for working at height that is unavoidable, the first choice will be to use any existing safe place of work that allows safe access and provides a safe working place. Where it is not reasonably practicable to work safely from the existing place of work, an alternative means of access will be needed. This will involve the use of work equipment. The following section provides specific details about the various type of work equipment which are employed with activities involving work at height.

Organisational Arrangements Every employer must ensure that all work at height is:

Properly planned,

Appropriately supervised, and

Carried out in as safe a way as is reasonably practicable.

Weather conditions and work equipment must be taken into consideration and must not jeopardise the health and safety of persons involved in the work. Emergency and rescue plans must also be in place.

Competence Employers must ensure that everyone involved in the work is competent by means of training and supervision. This also includes any involvement in organisation, planning, supervision and maintenance of equipment. Persons engaged in training must be supervised by a competent person.

Avoidance of risks from working at height Employers must conduct risk assessments to identify the risks involved with working at height. Based on the findings of the risk assessment, the employer must ensure that no work at height is carried out where it may be reasonably practicable to avoid. However where work at height cannot be avoided employers must take suitable and sufficient measures to prevent any person falling any distance liable to cause personal injury. This will include ensuring the work is carried out:

From an existing place of work, so far as is reasonably practicable; or if not

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Providing sufficient work equipment to prevent a fall occurring.

(In the case of obtaining access or egress) using an existing means.

Where risks of falling cannot be prevented employers must provide, so far as is reasonably practicable, work equipment to minimise the distance and consequences of a fall. In addition, the employer must provide such additional training and instruction or take other additional measures to prevent a person falling a distance liable to cause injury.

Selection of Work Equipment Employers must ensure that the most appropriate work equipment is selected and is suitable for that particular work at height. Consideration must be given to the working conditions and risks to the safety of persons at the places where the work equipment is to be used. The employer must give collective protection measures (such as guard rails) a priority over personal protection measures (such as safety harnesses) for the individual. Duration and frequency of use, access and egress, installation and removal, evacuation and rescue procedures must also be considered when selecting the most suitable work equipment.

Fragile Surfaces Employers must ensure that no one under their control goes into or near a fragile surface unless that is the only reasonably practicable way for the worker to carry out the work safely. Where a worker does work on or near fragile surfaces, employers must ensure that suitable platforms, coverings, guard rails etc. are provided to minimise the risk of a fall. If any risk of fall remains the employer must minimise the distance and consequences of a fall. Where persons at work may pass across or near, or work on, from or near, a fragile surface the employer must ensure that prominent warning notices are affixed at the approach of a fragile surface or danger area.

Falling Objects To prevent injury to any person the employer must take suitable and sufficient steps to prevent, so far as is reasonably practical, the fall of any material falling. Where it is not reasonably practicable the employer must ensure that steps are taken to prevent any person being struck by a falling object which is liable to cause injury. Nothing must be tipped or thrown from a height where it is liable to cause injury and materials and objects must be stored in such a way that its collapse, overturning or unintended movement is not likely to injure anyone.

Danger Areas Where the workplace contains an area in which there is a risk of someone falling or being struck by a falling object, the employer should introduce devices to prevent unauthorised persons from entering the area. The area must clearly indicate that it is a dangerous area and that unauthorised access is prohibited.

Inspections Employers must ensure that, where the safety of work equipment depends on how it is installed or assembled, it is not used after installation unless it has been inspected in that position.

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It must also be inspected at suitable intervals where the equipment may be exposed to conditions causing deterioration, and following the occurrence of any exceptional circumstances which are liable to result in dangerous situations. All inspections, tests and maintenance of work equipment must be done by a competent person by means of a visual or more thorough inspection and records must be kept until the next inspection is carried out.

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Title

Page

Working in Confined Spaces

DEFINITION OF ‘CONFINED SPACE’ ................................................................................................................... 3 HAZARDS ASSOCIATED WITH WORKING IN CONFINED SPACES ....................................................................... 4 RESTRICTED MOVEMENT .......................................................................................................................................... 4 LACK OF BREATHABLE AIR ........................................................................................................................................ 4 FLAMMABLE/ EXPLOSIVE SUBSTANCES AND OXYGEN ENRICHMENT......................................................................................... 5 BIOLOGICAL AND CHEMICAL HAZARDS .......................................................................................................................... 6 THERMAL ENVIRONMENT .......................................................................................................................................... 6 ELECTRICITY ........................................................................................................................................................ 6 MECHANICAL HAZARDS ............................................................................................................................................ 7 PSYCHOLOGICAL FACTORS ........................................................................................................................................ 7 CONTROLLING RISKS FROM WORKING IN CONFINED SPACES ......................................................................... 8 AVOIDANCE OF WORK IN CONFINED SPACES .................................................................................................................. 8 IF WORK IN CONFINED SPACES IS UNAVOIDABLE ............................................................................................................. 8


BSC International Diploma | Unit 1 Element 1B: Applied Health and Safety Management Study Unit 1B13 | Working in Confined Spaces Learning Outcomes When you have worked through this Study Unit, you will be able to:

1.B.13.1 Explain what is meant by ‘confined space’ 1.B.13.2 Describe the main hazards associated with working in confined spaces and explain how they may cause harm 1.B.13.4 Determine, implement, evaluate and maintain measures for controlling risks from working in confined spaces

Unit 10:

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Definition of ‘Confined Space’ Working in confined spaces can be particularly hazardous. A confined space is any enclosed (or substantially enclosed) space where there is a reasonably foreseeable specified risk associated with it, and includes chambers, tanks, vats, silos, pits, trenches, pipes, sewers, flues, wells or other similar spaces. The specific risks are:

Serious injury to any person at work arising from a fire or explosion.

The loss of consciousness of any person at work arising from an increase in body temperature.

The loss of consciousness or asphyxiation of any person at work arising from gas, fume or vapour.

The loss of consciousness or asphyxiation of any person at work arising from lack of oxygen.

Drowning or asphyxiation of any person at work arising from a free flowing solid or the inability to reach a respirable environment due to entrapment by a free flowing solid. ‘Free flowing solid’ means any substance consisting of solid particles and which is of, or is capable of being of, a flowing consistency, including flour, grain, sugar or other similar material.

Confined spaces are also often associated with work areas that have difficult or restricted access into them. The term ‘confined space’ has a wide application throughout industry. Some situations are fairly obviously confined spaces, such as reaction vessels, closed tanks, large-duct sewers, and enclosed drains. There are others, however, which are less obvious and that can be equally dangerous, such as, open-topped tanks that can include ‘bunded areas’ with high walls; vats, particularly where heavier-than-air gases or vapours may be present, for example, a fermentation tank in a brewery; closed and unventilated rooms; and medium-sized and large furnaces and ovens in which dangerous accumulation of gases can build up because of the restricted air circulation, even though the door is left open. Working space may be restricted, bringing workers into close contact with other hazards, such as moving machinery, electricity or steam vents and pipes. The entrance to a confined space, for example, a manhole, may make escape or rescue in an emergency more difficult.

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Hazards Associated With Working in Confined Spaces Restricted Movement Though a ‘confined space’ is not always small, many do in fact present restrictions to free movement. A restricted working space may bring workers into close contact with other hazards, such as moving machinery, electricity or steam vents and pipes. Many common confined spaces, such as chemical reactor vessels and sewers are accessed through relatively small entrances and manholes. This may present considerable difficulty not only to get in, but more importantly, to get out again in a hurry. It is also extremely difficult to retrieve an unconscious body through a manhole. The confined space may be further restricted by the equipment it contains and the protective equipment worn by personnel, for example, mechanical, electrical, or stirring or blending blades in mixing vessels, pressure lines for process materials or steam, or any electrical services for lighting, tools, cleaning equipment. Liquids and solids can suddenly fill the space, or release gases into it, when disturbed. Free-flowing solids such as cement or grain can also partially solidify or ‘bridge’ in silos, causing blockages that can collapse unexpectedly. Some of the above conditions may already be present in the confined space. However, some may arise through the work being carried out, or because of ineffective isolation of plant nearby, e.g. leakage from a pipe connected to the confined space. The enclosure and working space may increase other dangers arising through the work being carried out, e.g. machinery being used may require special precautions, such as provision of dust extraction for a portable grinder, or special precautions against electric shock; gas, fume or vapour can arise from welding, or by use of volatile and often flammable solvents, adhesives.

Lack of Breathable Air Toxic Atmospheres Poisonous gas, fumes or vapour can build up in sewers and manholes and in pits connected to the system, enter tanks or vessels from connecting pipes, and leak into trenches and pits in contaminated land, such as old refuse tips and old gas works. Certain toxic gases may be present, for example: hydrogen sulphide from sewers or decaying material; carbon monoxide from internal combustion engines (petrol or diesel) or the incomplete combustion of LPG. Certain fumes and vapours could be present from chemicals, for example, ammonia, chlorine or petrol and solvents. Specific examples include:

Carbon dioxide (CO2) in concentrations of above 6% becomes toxic by interfering with respiration. The victim begins involuntarily to breathe very heavily in response to elevated gas levels in the blood, and will ultimately lose consciousness.

Carbon monoxide (CO) is much more deadly, being a cumulative poison that will kill if one part in 400 is breathed for approximately 20 minutes, and higher concentrations act much more quickly. (It blocks the oxygen transport mechanism by attaching irreversibly to receptor sites on the haemoglobin in the blood.) There is no warning of the presence of CO, other than turning blood the characteristic cherry red of carboxyhaemoglobin, as it

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is undetectable to our senses (and it has the same density as air and so becomes rapidly and evenly dispersed).

Both gases are combustion products and carbon dioxide is also produced by the microbial decay of natural materials (including fermentation) as well as respiration. Toxic effects can be expected in any situation where the decay of natural materials or combustion processes occur (e.g. motor vehicle exhaust fumes).

Hydrogen sulphide (H2S) (bad egg gas) gives warning of its presence at low concentrations by its characteristic odour. It is, however, extremely toxic and also saturates the olfactory membrane so that the sense of smell rapidly becomes paralysed. Sudden exposure to high levels may not be detectable. Again, it may occur where natural materials decay - but in the absence of oxygen - hence in rotten eggs.

Oxygen Deficient Atmospheres Depletion of oxygen can occur:

Through displacement where the addition of a gas or vapour to the space displaces the oxygen in that atmosphere, e.g. purge gas or pipe freezing, or gas leaking from elsewhere.

Through consumption where the oxygen in the atmosphere is depleted by a chemical reaction or biological process occurring in the space, for example, oxidation (rusting) and bacterial growth.

Through welding operations or by people working, or any process of combustion.

Where there is a reaction between some soils and the oxygen in the atmosphere.

Following the action of groundwater on chalk and limestone, which can produce carbon dioxide and displace normal air.

Through production of carbon dioxide from fermentation processes or naturally from the rocks or soil, or from combustion processes

Flammable/ Explosive Substances and Oxygen Enrichment Certain gases and vapours in small concentrations can pose a hazard and produce either a fire or an explosive atmosphere, for example, LPG, acetylene, propane, butane, oxygen, methane, hydrogen sulphide, acetone, toluene, alcohol, white spirit, thinners, solvents, hydrogen depending on their explosive range in the atmosphere. Specific examples of flammable situations include:

Methane (CH4) occurs naturally as a microbial degradation product under anoxic conditions and is capable of migrating through water, unlike all other hydrocarbons. Such a mechanism created the explosive atmosphere in an underground water treatment works that tragically killed a number of visiting parish councillors in the UK. It is odourless but should be suspected if the air smells marshy.

Natural gas (mains gas) is methane but is odourised by addition of small amounts of mercaptans, and is thus readily discernible in the event of a leak. Propane and butane (liquefied petroleum gases) are dense and will accumulate in confined spaces in the event of a leak that could typically occur from welding equipment.

Acetylene is another welding gas that readily forms explosive atmospheres. In very high concentrations, these gases also act as asphyxiants by diluting the oxygen.

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Petroleum vapours can be formed if petrol is spilled into the ground, and may migrate over distances. The Mexico City sewer explosions were due to petrol spilled into the system and this is but one example of many accidents of this type.

Certain (combustible) dusts in high concentrations can also present an explosion risk. Another related cause of fire is oxygen enrichment. Generally, this only occurs when oxygen is artificially introduced into a space (such as a leak from an oxygen cylinder introduced as part of a welding kit) or where the chemical contents of the space release oxygen as they degrade. Any organic material, for example, oil and grease, will become highly combustible and paper, material or clothing will burn fiercely. If an oxygen-enriched atmosphere is present, the space should be ventilated until normal oxygen levels are obtained.

Biological and Chemical Hazards It is common for confined spaces that need to be entered for cleaning or maintenance to have been used previously for storage. Residues remaining on internal surfaces may give off gas, fume or vapour. The characteristics of the materials that were stored in the space may present a hazard. Other chemical and biological hazards of working in confined spaces include:

Poisonous or flammable gases can collect in manholes, etc. in contaminated ground, for example, in old gasworks, plating works and ground near underground petrol tanks, or in coal-bearing ground and old refuse tips.

In manholes, pits or trenches connected even temporarily to sewers, there can be a buildup of flammable and/or poisonous gases and/or insufficient oxygen in the air to breathe.

Sludges and other residues in tanks, pits, etc., if disturbed, may partially fill the confined space with dangerous gases.

Leptospirosis (Weil’s Disease) from rat’s urine.

Microscopic pathogens - a pathogen is an agent that causes disease.

Bacteria.

Viruses.

Insect larvae.

Thermal Environment Hot conditions can lead to a dangerous increase in body temperature and may result in loss of consciousness of any person at work, as well as heat stress, fatigue or exhaustion and/or loss of fluids. Increasing the number of openings might improve ventilation. Adequate rest breaks and cool drinks may help to alleviate such conditions. Mechanical ventilation may be necessary to ensure an adequate supply of fresh air and will be essential where portable gas cylinders and diesel-fuelled equipment are used inside the space, because of the dangers from build-up of engine exhaust. Job rotation is also an effective method of reducing the effects of heat.

Electricity Any electrical equipment used in a confined space will inevitably create some risk. All of the normal risks associated with electricity will be present, often in an exaggerated form because of the nature of the space and the work being undertaken.

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The risk of electric shock may be increased if the confined space is of metal construction – because of the low-resistance conducting nature of the structure. The internal environment may be wet, and humidity levels in the atmosphere may be high, again lowering electrical resistance and increasing risks. Very significantly, a flammable gas or vapour may be present, and electrical equipment might provide the ignition source that leads to fire or explosion.

Mechanical Hazards By its very nature, work in a confined space may be restricted, bringing workers into close contact with other hazards, such as moving machinery or electricity. In confined space work, the hazards presented could include:

Electrical equipment, if not correctly selected and maintained, presents the risk of electric shock. In addition electrical equipment, including such things as torches, must be intrinsically safe if there is any risk of a flammable atmosphere. If the environment is hostile in any other way – it could, for example, be wet – further restrictions on the use of electricity should be considered.

A portable grinder may produce dust and provision may need to be made for dust extraction.

Gas, vapour or fumes may arise from welding.

The confined space may contain baffles or internal structures that the worker can strike against, increasing the risks of bumps, bruises, lacerations and even broken bones.

Some spaces will contain mechanical moving parts, such as agitators, scrapers and augers. These moving parts can give rise to very significant risks of injury and, in many instances, death by crushing, drawing or entanglement, if not correctly isolated.

Psychological Factors Claustrophobia is usually described as a fear of enclosed spaces. A more accurate description might be ‘a fear of not having an easy escape route’ because for anyone who experiences this phobia, this is the predominant fear. Claustrophobia is an issue in the context of confined spaces for very obvious reasons. The worker who suffers from claustrophobia may be severely traumatised by their work experience – this is an immediate psychological hazard. The worker may panic and, if severely claustrophobic, will be incapable of rational thought and unable to control their actions as the innate desire to escape overwhelms controlled thought. In these instances, it is possible that the worker may, through their panicked actions, injure themselves and/or their colleagues. If the worker does not act to affect their escape, they may be so consumed by their fear that they become incapable of moving. In these circumstances, some sort of rescue will need to be carried out. It is worth considering that workers may not be aware of their claustrophobia, may not be willing to reveal it (due to fear of peer-group ridicule or workplace discrimination) or may not actually experience fear except in exceptional circumstances. For example, consider working in a 1.8 m high tank, 3 m long and 2 m wide, as opposed to walking down a 1.8 m high sewer tunnel that is 1.5 km long. A claustrophobic would dislike both locations. A nonclaustrophobic but experienced worker would probably cope comfortably with the tank, but might become increasingly unsettled in the sewer tunnel. An experienced sewer worker would feel at ease in the tunnel.

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Controlling Risks from Working in Confined Spaces Avoidance of Work in Confined Spaces Wherever possible, the need to enter and work in a confined space should be avoided. However, where this is not possible, a thorough risk assessment must be carried out to enable suitable control measures to be introduced. No person should enter a confined space to carry out work unless it is not reasonably practicable to achieve that purpose without such entry. Better work-planning or a different approach can reduce the need for confined space working, such as by:

Modifying the confined space itself so that entry is not necessary.

Having the work done from outside, for example, clearing blockages in underground chambers by use of remotely operated rotating flail devices, vibrators or air purgers.

Carrying out inspection, sampling and cleaning operations from outside the space using appropriate equipment and tools.

Using remote cameras for internal inspection of vessels.

If Work in Confined Spaces is Unavoidable Risk Assessment Where work in a confined space is needed a thorough risk assessment must be carried out to enable suitable control measures to be introduced as part of a Safe System of Work. The risk assessment should consider:

Hazards associated with confined space.

Hazards associated with work that is to be carried out in the confined space; and

The combined effects of both of the above.

The assessment will also include consideration of:

The task.

The working environment.

Working materials and tools.

The suitability of those carrying out the task.

Arrangements for emergency rescue.

Safe System of Work for Entry into Confined Spaces We have seen previously that employers must provide a safe system of work, and this is vital when carrying out confined space entry and work. Numerous confined space accidents occur, many causing multi-fatalities due to the lack of, or failure to comply with, a detailed operating procedure. This procedure should be based on a permit-to-work system. Application of Permits-to-Work The only way in which it is possible to ensure a safe system of working in confined spaces is by using a permit-to-work, so this is to be considered a mandatory requirement. The permit system must be under the control of a competent manager and will detail the operating procedures to be adopted.

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The key precautions to be included in a permit-to-work are:

Isolation of the confined space.

Adequate ventilation.

The absence of substances likely to give off fumes.

Atmospheric testing for the presence of dangerous fumes.

A supply of respirable air.

A specified working period.

Rescue and resuscitation arrangements.

If the atmosphere can be made safe by venting the space, perhaps employing forced ventilation, then this must be done. The atmosphere should be tested and shown to be safe before entry by any person. Multi-test equipment is available which can measure oxygen concentration, flammables and H2S at the same time. (CO2 is not normally measured because it is practically difficult to do so; however, vigilance should be exercised and any unusual physiological response, such as elevated breathing rate, should be investigated.) The permit must specify any precautions and instructions appropriate to the area. There is also a requirement to ensure that the employee understands the entry permit. This provides an additional safeguard to ensure that the safe system of work is strictly followed. Operation of a Permit-to-Work System in Relation to Entry into Confined Spaces The first and most important step is the assessment of the situation by a responsible person familiar with the technical aspects of the job. He or she must be given time to consider the job in detail and thus must not have too heavy a workload. Assessment Factors to consider during assessment include:

Most important: is entry really necessary?

Work needing to be done.

Methods of working.

Hazards inherent in the plant.

Hazards from neighbouring plant.

Steps necessary to make the job safe.

Withdrawal from Service The person in charge of the process should sign the permit. Warning notices should be displayed and all plant operators notified. Isolation Plant should be physically disconnected from other items of plant. Reliance on shut-off valves, water seals or even a single brick wall has led to fatal accidents. Signage The risk assessment carried out on the confined space will indicate what specific hazards are present and, consequently, what signs will be required.

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In general, indications through signage will be required to show that the area is a confined space, entry is prohibited and restricted to authorised persons only, and that PPE and other specific controls are mandatory. Barriers In addition to signage, physical barriers are required to prevent unauthorised entry to the confined space. It is necessary to ensure that no one enters a confined space unless:

They are trained and authorised to do so.

They are wearing approved breathing apparatus if dangerous fumes are present or in an oxygen-deficient atmosphere.

They have been authorised to enter by a responsible person.

Where practicable, they are wearing a belt or harness with a rope securely attached.

A person holding the free end of the rope is keeping watch outside and capable of pulling the person out.

Air Quality Testing Hazardous atmospheres must not be present at any time during an entry operation and it is necessary to check that the atmosphere is free from both toxic and flammable vapours and that it is fit to breathe. Testing should be carried out by a competent person using a suitable gas detector that is correctly calibrated. Great care needs to be exercised in gas testing as flammable, explosive or toxic gases can exist alongside oxygen and their presence in small quantities can cause a serious hazard. Breathing apparatus is required if entry into the confined space in order to test the air is necessary. Gas testing involves testing the atmosphere at all locations, drain points, instrument bridles, orifices and at a high and low level, as some gases due to their density tend to lie in low positions, e g. hydrogen sulphide. An individual’s sense of smell should not be relied upon as an accurate measure of atmospheric conditions, as some gases (e.g. hydrogen sulphide) tend to paralyse the sense of smell at low concentrations and it varies between individuals, while other gases (e.g. carbon monoxide) have no smell. Where the risk assessment indicates that conditions may change, or as a further precaution, continuous monitoring of the air may be necessary. Atmospheric testing includes the following:

A flammable gas, vapour, or mist in excess of 10% of its Lower Explosive Limit (LEL).

An atmospheric oxygen concentration below 19.5% or above 22%.

An atmospheric concentration of any substance which could result in employee exposure in excess of the permissible limits.

An airborne combustible dust at a concentration that obscures vision at a distance of 5 feet (1.52 m) or less.

Any atmospheric condition recognised as immediately dangerous to life or health.

Personal Protection The risk assessment carried out on the confined space, referred to above, will indicate what specific hazards are present and therefore what personal protective equipment will be required.

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Breathing apparatus will be required if dangerous fumes are present or if the atmosphere is oxygen-deficient. Other typical activities carried out in the confined space might include, for example, welding, cleaning, equipment repair and maintenance. Consequently, personal protective equipment for UV, hot surfaces, chemical exposure, rough work and head protection might be required. This should be specified as a component of the safe system of work that is devised from the risk assessment.

Means of Access and Egress A safe method of access or egress should be provided to allow ready access to, and egress from, the confined space itself. You should bear the following in mind:

Experience has shown that the size of a manhole to allow access for an SCBA (SelfContained Breathing Apparatus) wearer is 575 mm. Smaller openings than this are, however, common, for example, road tankers. The smaller openings may therefore limit the type of BA to more compact types, such as those using an airline.

Dependent on the activities involved, a number of access and egress points may be required.

Entry should be authorised by a responsible person, i.e. by means of a permit-to-work system.

Where practicable, he or she should wear a belt or harness with a rope securely attached.

A person keeping watch outside, and capable of pulling him or her out, must hold the free end of the rope.

Alternatively, a person may enter or work in a confined space without breathing apparatus, provided that:

Effective steps have been taken to avoid ingress of dangerous fumes.

Sludge or other deposits liable to give off dangerous fumes have been removed or cleaned.

The space contains no other material liable to give off such fumes.

The space has been adequately ventilated and tested for toxic, flammable and explosive gases or fumes.

There is a supply of air adequate for respiration.

The space has been certified by a responsible person as being safe for entry for a specified period without breathing apparatus.

Emergency Arrangements No person shall work in a confined space unless suitable and sufficient arrangements for their rescue in an emergency have been made. Effective arrangements for raising the alarm and carrying out rescue operations in an emergency are essential. Emergency plans will depend on the nature of the confined space, the risks identified and consequently the likely nature of an emergency rescue. Staff and equipment should be readily available for emergencies and suitably trained in the operation of all equipment used (including first- aid). There need to be properly trained people, sufficiently fit to carry out their task, ready at hand, and capable of using any equipment provided for

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rescue, e.g. breathing apparatus, lifelines and fire-fighting equipment. Rescuers also need to be protected against the cause of the emergency. Equipment should consist of:

Breathing apparatus sets.

Rescue and resuscitation equipment (such as an oxygen therapy unit and perhaps an automatic defibrillator), harnesses, lifting tripods, winches, stretchers, first-aid equipment.

Means of communication (such as 2-way radios, which are suitable for explosive atmospheres if applicable) and summoning help.

Lifelines.

Rescue teams must not enter without breathing apparatus. They must be thoroughly trained in rescue techniques, first-aid and use of resuscitators. An essential part of such a rescue plan might include shutting down adjacent plant before attempting emergency rescue and communication with local emergency services (e.g. the fire brigade), remembering to pass on information about the particular dangers in the confined space.

The Emergency Team It is considered best practice to provide the same team structure for rescue as would be for normal entry operations. That means, therefore, that an entry supervisor, an attendant and an entrant, at least, would be required to perform a non-hazardous confined spaces rescue. The number of people required to perform an effective rescue will obviously depend on the complexity of the incident. Personnel must receive training prior to performing rescues. Rescuers should also be sufficiently fit to carry out rescues, as well as being capable using any equipment needed for rescue. Emergency Team Training The training needs for each individual member of the rescue will vary according to their designated role. It is important that refresher training is organised and available on a regular basis, for example annually. Training should include the following, as is appropriate:

Likely causes of an emergency.

Use of rescue equipment, such as: breathing apparatus, lifelines.

The ‘check procedures’ to be followed when putting on and using apparatus.

Checking of correct functioning and/or testing of emergency equipment.

Identifying defects, and dealing with malfunctions and failures of equipment during use.

Works, site or other local emergency procedures, including the initiation of an emergency response.

Instruction on how to shut down relevant process plant, as appropriate.

Resuscitation procedures and, where appropriate, the correct use of relevant ancillary equipment and any resuscitation equipment provided.

Emergency first-aid and the use of the first-aid equipment provided.

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Use of fire-fighting equipment.

Liaison with local emergency services in the event of an incident, providing relevant information about conditions and risks, and providing appropriate space and facilities to enable the emergency services to carry out their tasks.

Rescue techniques including regular and periodic rehearsals and exercises. This could include the use of a full-weight dummy. Training should be realistic and not just drill based.

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Title

Page

Lone Working

MAIN RISKS ASSOCIATED WITH LONE WORKING ............................................................................................. 3 ASSESSING RISKS FOR LONE WORKING ............................................................................................................ 4 CONTROLLING THE RISKS FROM LONE WORKING ............................................................................................ 7 LONE WORKING POLICY ........................................................................................................................................... 7 SAFE SYSTEM OF WORK ........................................................................................................................................... 7 SUPPORT AND RESOURCES ........................................................................................................................................ 8 SUITABLE EQUIPMENT ............................................................................................................................................. 8 AUTHORISED ACCESS AREAS AND PROHIBITED AREAS ....................................................................................................... 8 COMPETENCY ........................................................................................................................................................ 9 COMMUNICATION STRATEGIES ................................................................................................................................... 9 EMERGENCY PROCEDURES ...................................................................................................................................... 10 PLANNING LONE WORKING ..................................................................................................................................... 10


BSC International Diploma | Unit 1 Element 1B: Applied Health and Safety Management Study Unit 1B14 | Lone Working Learning Outcomes When you have worked through this Study Unit, you will be able to:

1.B.14.1 Outline the main risks associated with lone working 1.B.14.2 Assess the risk of harm from lone working 1.B.14.3 Determine, implement, evaluate and maintain measures for controlling risks from lone working

Unit 11:

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Main Risks Associated With Lone Working Lone workers are considered to be “those who work by themselves without close or direct supervision”. It follows then, that lone workers do not necessarily work in complete isolation from other people, but work without the benefit of frequent contact with colleagues and managers. Lone working may take place during the majority of the working day or over shorter periods of time. Two broad groups of workers exist:

Those working in fixed premises. For example: −

Lone workers in small establishments, for example, shops and garages.

−

Home workers.

−

Those working in a part of a building isolated from others, for example, maintenance staff.

−

Those working outside of normal hours, for example, security, cleaners and maintenance staff.

Those working away from their fixed base as mobile workers. For example: −

Construction, decorating, vehicle repairers.

−

Agricultural and forestry workers.

−

Social workers, home helps, sales representatives.

−

Transport workers and vehicle drivers

People who work alone are exposed to the same hazards as other employees, but the risk of injury or ill-health may be greater. The main risks associated with lone working are:

Lack of immediate assistance in the case of injury or ill-health.

Violence against the person.

A lone worker may not be able to secure assistance as readily as when working with a group of co-workers, and response times may be longer when working in isolated locations. Lone workers are potentially more vulnerable to incidents of violence and aggression, with a lack of immediate assistance possibly increasing the severity of any physical attack. Other risks to the lone worker may include inadequate provision of rest, hygiene and welfare facilities, and psychosocial issues resulting from a feeling of isolation and a lack of support from colleagues and supervisors. Manual handling activities may also present a problem where the lone worker cannot easily gain assistance.

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Assessing Risks for Lone Working The employer has a responsibility to ensure the health, safety and welfare of their employees, including those who are engaged in lone working activities. The overriding consideration is whether the job can be adequately controlled by one person which would be determined through a risk assessment process. Any risk assessment will need to take into account the specific hazards and the additional risks associated with lone working. Individual medical fitness and suitability for lone working may determine selection criteria. Individuals with medical conditions, such as a history of heart problems or diabetes, may not be best suited to lone working. Issues such as age, gender and experience may also affect suitability for lone working. For example, young persons, the elderly and women may be more vulnerable where exposure to hazardous substances occurs, or where aggressive situations are likely to arise. A more experienced person may well be better able to cope, whatever situation arises, as they may be better able to make better decisions. For instance, they may be less likely to allow themselves to be isolated in vulnerable areas and may be better able to deal with an aggressive customer and to calm the situation. Account should be taken of normal work and foreseeable emergencies, and consideration given to:

The time the work is carried out.

The location.

The type of work activity.

Time Whilst the risks associated with a work activity during normal working hours may be minimal, working outside of normal hours can increase those risks. Consider a cleaner working alone in a small office environment, outside of normal hours. Ordinarily, during normal office hours, immediate assistance would be available in the event of an emergency. However, it is far more difficult, if not impossible, for the cleaner to summon assistance should they suddenly become ill, or incapacitated due to an injury. If assistance could be summoned, it is likely to come from an external source, which may result in a slower response. Normal emergency procedures are unlikely to be functional outside of normal working hours. Where a work activity requires working late at night or after dark, particularly in the case of mobile workers, the employee is likely to be more vulnerable to incidents of violence and aggression, and may not have the ability to summon assistance immediately. Any risk assessment would need to consider whether the particular activity can be completed safely at night. Would there be a requirement to visit high-risk areas or locations? Will there be contact with members of the public and, if so, are they already known to the lone worker or their team? Do they have a history of aggression or violence? Is there a need to travel distances on foot? Will reduced visibility, both of the employee and by the employee, introduce increased risks? Working long hours, being on-call, working at night or working varying shift patterns can have an adverse impact on health, resulting in stress, psychosocial and physical problems. Tiredness can impair the ability to think rationally, and can reduce response rates. For example, security personnel working at fixed premises throughout the night may well become bored, resulting in a lack of concentration and motivation, and hence poor performance. There are periods at night when the human is physiologically less able to perform well. It is important to consider whether work activities are sufficient to maintain alertness.

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Location Lone workers will often work in locations not under the control of their employer, or in difficult to reach locations, such as plant rooms. Consideration will need to be given to whether the particular workplace presents a special risk to someone working alone. Is there safe egress and exit to and from the workplace? Is the location itself hazardous due to its geographical isolation, remoteness or client make-up, the nature of the activities or hazards at the premises, or is it hazardous due to poor standards of health and safety? Where a location is geographically isolated or remote, emergency assistance can be problematic. In addition, where travelling to remote locations is part of the work activity, consideration should be given to the possibility of vehicle breakdown in rural or isolated areas, and account should be taken of any lack of mobile phone service availability where mobile phones are relied upon as a means of contact and communication. The lone worker may also be working in relative isolation, but within the usual workplace. For example, working in plant or machine rooms and laboratories. Consideration should be given to the extent of isolation, the visibility of the worker to others, and the ability to summon immediate assistance should it be required. The likelihood of incidents of violence and aggression depends on a number of factors, including the location to be visited and the likelihood of contact or interaction with members of the public. Certainly, working alone in remote locations may leave the worker more vulnerable, depending upon the circumstances. In contrast, many workers may be visiting geographical areas that are highly populated, but are considered to have a high potential for violence. Any risk assessment should consider whether it is possible to achieve safe lone working in such circumstances. The location of the worker will also determine the availability of rest, hygiene and welfare facilities. The mobile worker is likely to be dependent upon public facilities whereas many others may be reliant on client facilities. The adequacy of available facilities should be considered, and whether their use increases the vulnerability of the worker, for example, where they are shared with members of the public. Home workers can be particularly at risks from hazards, and the lack of support and procedures to deal with them. Consideration needs to be given to the suitability of premises, particularly in terms of the opportunity for emergencies, such as fires, to occur. The need for regular servicing, maintenance and testing of equipment, and systems for reporting problems or gaining emergency assistance, will need to be assessed. In many cases, domestic premises will not be as well-equipped or well-maintained in terms of safety, as a business premises. As we identified earlier, lone workers are exposed to the same hazards as other employees but, when working away from the home base, risks are less easy to control and standards of control may vary. The employer would need to assess the risks posed by the premises, and work with the occupier to ensure the health safety and welfare of employees. The lone worker may be entering premises where hazardous substances or mechanical handling equipment are used, but not be familiar with the risks. It is not always practical to assess each and every premises to be visited, for example, in the case of health care visitors, who visit members of the public in their homes. In such cases, it may be appropriate to complete a generic assessment of the activity. The availability of emergency assistance, either from the occupier of the premises, external sources, or the employer of the lone worker, would need to be considered.

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Type of Work The type of work carried out by lone workers is highly variable. Account would need to be taken of any extra demand on the lone worker’s physical and mental stamina, as well as any individual characteristics, such as ill-health, that would preclude the individual being exposed to the specific work. Examples of high-risk activities would include:

Confined space working.

Working with hazardous substances, high-pressure systems or dangerous machinery.

Moving equipment or machinery.

Service industries where cash handling is involved.

Working in extreme weather conditions.

Laboratory functions.

There would be a need to consider whether all the equipment, substances and machinery can be safely handled, used and transported by one person. Are weather conditions such that heat stroke or hypothermia could result? Is the worker more vulnerable to incidents of violence and aggression due to the handling of cash? Is there an increased likelihood of injury occurring and, therefore, a critical need for immediate assistance in an emergency? Is the injury of a type that will potentially reduce or remove the lone worker’s ability to summon assistance? Consider two specific work activities: a taxi driver and a long distance lorry driver. Both are likely to be lone workers, but the taxi driver will be carrying cash and interacting with members of the public as part of the work activity. Late night taxi drivers may be dealing with customers who have been consuming alcohol, leading to an increased tendency for violent and aggressive behaviour. As such, the taxi driver is far more vulnerable to incidents of unplanned violence and aggression. Having said that, the long distance lorry driver, whilst not in constant contact with the public, may be carrying a valuable load, resulting in an increased vulnerability to more organised instances of violence and aggression. In both cases, summoning immediate emergency assistance will be a problem. The type of work, and the hazards that the lone worker is exposed to, will determine the level of risk associated with a lack of immediate emergency response and the potential for violent incidents. Consideration should also be given to the need for the worker to make immediate and difficult decisions. Without the benefit of discussion and supervisory support, psychosocial problems such as stress and a feeling of isolation can result.

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Controlling the Risks from Lone Working Lone workers must not be at greater risk than other employees, and therefore additional control measures may be required. A situation may exist where employees work on another premises, owned or occupied by someone other than their employer. In such a case, cooperation and co-ordination become important in terms of sharing hazard information, and ensuring the co-ordination of emergency procedures and the availability of welfare facilities. Where a risk assessment identifies that the activity, through the nature of the work, or its location or time, cannot safely be carried out by a lone worker, alternative arrangements will be required. In certain high-risk activities, at least one other person may need to be present. These include, for example, in fumigation, high-risk confined space working, or during electrical work at or near exposed, live conductors.

Lone Working Policy The lone working policy should be clear, effective and workable. It should also serve to establish a ‘culture of confidence’, which is necessary to encourage employees to report issues and problems. Many organisations will develop a separate violence at work policy, which will identify what is deemed to be acceptable or unacceptable behaviour, and will incorporate reporting, complaints and appeals procedures. A lone working policy should give a clear definition of what is considered to be lone working, and show management commitment to the identification, assessment and control of lone working situations, and the role of competent persons. The scope and applicability of the policy should be made clear. It may be possible and appropriate to determine and identify those activities where lone working should not occur. Importantly, policies should encourage employees to leave immediately if they feel vulnerable or at risk, and to determine when it is appropriate to refuse to visit or to request assistance.

Safe System of Work A safe system of work is defined as ‘the integration of personnel, articles and substances in a suitable environment and workplace to produce and maintain an acceptable standard of safety’. Account should be taken of foreseeable emergencies. It may be possible to re-organise the way jobs are done to provide a safer system of work. Procedures should be in place and their implementation should be monitored and their effectiveness reviewed. Examples of appropriate procedures may include those that:

Enable lone workers to request additional staff to assist in certain tasks, for example, manual handling, where hazardous substances and equipment are likely to be present, or where a client is known to be aggressive or violent.

Improve information gathering and sharing, both within the organisation and with external organisations, about clients with a history of violence, or areas of high risk.

Allow alternative arrangements, for example: −

Meeting clients or patients away from the home where home visits are not essential, or it is a first visit and the client is unknown.

−

Allowing accompanied first visits to a new premises where the hazards are not yet known

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Eliminate the need for handling cash, or use additional support and assistance at times when cash is handled.

Ensure premises to be visited are assessed to determine the hazards and existing controls.

Allow the effective reporting of problems and incidents, with procedures for addressing any issues or concerns raised.

Support and Resources Adequate staffing levels should be available to ensure competent assistance is available when required, and that cover for break and holiday periods is accessible. Resources required by the lone worker, such as equipment, administrative tools, relevant information and communication equipment, should be readily available to prevent the work becoming difficult to complete or to carry out safely. To reduce the potential for feeling isolated, arrangements should be made to keep in touch and up to date with colleagues and managers. Forms of support and contact may include: regular newsletters, seminars, training events and regular staff meetings. Regular visits to the lone worker at their work location can keep them in touch, and consideration may be given to altering the work activity so that it results in a combination of lone work, and work carried out in the base environment. A worker forced to face potentially difficult situations alone can experience feelings of reduced control and increasing feelings of stress. The lone worker should feel confident that support and back up is readily available should they need it.

Suitable Equipment Equipment used by any employee should be suitable for the task, and be well-maintained. The lack of immediate assistance to lone workers makes this requirement of even more importance. Regular, planned preventative maintenance should form part of the safe system and, where applicable, equipment should be examined, inspected and tested. All equipment, especially powered tools and access equipment, such as ladders, should be capable of being used safely. As the person will be working alone, it is also essential that the equipment can be set up by one person alone. Users should check that equipment is free from defects, has been regularly maintained, and, where applicable, has a current test label or certificate. Simple and accessible procedures for the reporting of defects should be available, with quick and effective replacement procedures, where appropriate. Specific consideration may need to be given to home working, as standards of inspection and maintenance are seldom appropriate to a work environment. Consideration could be given to specifying certain standards before people can work at home, for example, in relation to electrical systems, lighting, ventilation, escape routes, and the use of domestic equipment. Where driving forms part of the lone workers activities, particularly when using their own cars for business, regular checks may need to be made on annual vehicle testing, insurance documentation and the validity of licences.

Authorised Access Areas and Prohibited Areas Door entry systems for people working in isolated areas may be required to prevent uncontrolled access by members of the public or unauthorised persons. Any door entry system

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should not then prevent quick exit by the lone worker or emergency access, should it be required. Where visibility through a door is not available, an intercom will allow the lone worker to determine whether or not to give access to other persons. Procedures for signing in and out should also be in place. Lone workers should be aware of prohibited areas in the workplace, and should not be able to gain access to areas where they are not required to enter to carry out their work, particularly where hazardous areas are present.

Competency Depending on the work activity, selection criteria may be applied to ensure individuals are suitable in terms of physical and mental stamina, and medical fitness. In most lone working situations, the employee should be an experienced individual. Employees new to the job may need to be accompanied at first, as part of their training programme. Lone workers cannot easily ask more experienced colleagues for help with dangerous tasks or equipment, so extra training and information may be required. It is particularly important that they have the information and training they need to avoid panic reactions in unusual situations. They should clearly understand the risks of their work, the precautions that are needed and what they should do in an emergency. Lone workers should have a level of competence that will allow them to determine when it is unsafe to continue work and when they should feel able to stop working if necessary. Where employees are exposed to potentially violent or aggressive situations, training in interpersonal skills, assertiveness and handling of difficult situations is likely to be needed. It may additionally be appropriate to ensure members of staff are aware of, and can implement, ‘break away’ techniques. Where driving forms a significant part of the worker’s activities, training in advanced driving techniques may well be appropriate. Sufficient information and instruction on procedures should be readily available to ensure they are aware, for example, of when and how to request additional assistance, and how to report incidents. Training and information requirements should be regularly reviewed for appropriateness and effectiveness.

Communication Strategies Means of communication may involve the use of two-way radios, pagers or mobile phones. Any means of communication should be regularly tested for correct operation, and records kept of the tests. Maintaining regular contact may be an appropriate control in some situations, with the contact intervals being determined by the level of risk. Specifying times for contact will enable the alarm to be raised where no contact is made. Lone workers should leave details of their itinerary, and report back to base at regular intervals. Expected arrival and departure times should be known by colleagues or clients, with procedures in place to respond should there be any deviation from the agreed times. For non-mobile workers periodic visits at regular intervals by a ‘buddy’ or supervisor may be appropriate. In more high-risk situations, constant or intermittent mechanical or electrical surveillance, with central monitoring, should be considered. Automatic warning systems can be used, sending an automatic warning to a pre-determined person if the lone worker fails to check in.

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Whatever the method of monitoring, the person designated to check the worker must be knowledgeable of the work activities of the lone worker, and have the capability of implementing emergency procedures should they be required. Staff should be confident that immediate action will be taken if their return from a lone working visit is overdue.

Emergency Procedures A safe means of entry and exit to the workplace should be available, including in an emergency and, where possible, a named, competent person should be identified as a point of contact at the lone worker’s place of work. It may be appropriate to train the lone worker in first-aid where no other immediate alternatives will be available. Adequate first-aid facilities should be available either at the premises or carried by mobile workers. Contact procedures should be in place so that the alarm can be raised, and prompt medical attention provided, if there is an accident or sudden illness. Personal attack alarms may be used to draw attention in the event of an emergency, but these will only be effective if there are people within the audible range, and with the knowledge to respond. Panic alarms connected to a central point of control can be used to summon assistance quickly. Such alarms should be readily accessible to the employee, possibly carried by the employee, and connect to a control point that can activate a suitable emergency response. It may be appropriate to use silent alarms connected to a central control point that will draw attention to the need for assistance, without escalating a potentially violent situation. Steps should be taken to ensure control measures are used and remain appropriate. Regular checks should be made to ensure the required response is activated within the required time frame.

Planning Lone Working The UK’s HSE guidance document, INDG73 (Rev), Working Alone in Safety, Controlling the Risks of Solitary Work available online at www.hse.gov.uk serves as good practice and an excellent source of information for planning lone working.

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Title

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Violence Against Employees

ASSESSING THE RISK OF VIOLENCE .................................................................................................................. 3 DEFINING VIOLENCE ............................................................................................................................................... 3 SECTORS OF EMPLOYMENT ........................................................................................................................................ 3 WORK ACTIVITIES .................................................................................................................................................. 3 CONTROLLING THE RISK OF VIOLENCE AGAINST EMPLOYEES .......................................................................... 5 1 – FINDING OUT IF YOU HAVE A PROBLEM. ................................................................................................................... 5 2– DECIDING WHAT ACTION TO TAKE. .......................................................................................................................... 6 3– TAKE ACTION.................................................................................................................................................... 9 4 – CHECK WHAT YOU HAVE DONE. ............................................................................................................................. 9


BSC International Diploma | Unit 1 Element 1B: Applied Health and Safety Management Study Unit 1B15 | Violence Against Employees Learning Outcomes When you have worked through this Study Unit, you will be able to:

1.B.15.1 Assess the risk of violence against employees 1.B.15.2 Determine, implement, evaluate and maintain measures for controlling the risk of violence against employees

Unit 12:

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Assessing the Risk of Violence Defining Violence A common definition of violence is:

“Any incident in which an employee is abused, threatened or assaulted by a member of the public in circumstances arising out of the course of his or her employment.” This definition makes reference to abuse, threats or assault by members of the public, so it is in organisations that require employees to come into contact with members of the general public during their work where the risk of assault or threat exists. In general, persons especially at risk will include those who are handling cash, those dealing with members of the public generally, and particularly those employed in an enforcement role or who have to handle difficult people. Another group of workers that is at particular risk is lone workers. The issue of lone working and the particular risks involved were considered in detail in Study Unit 1B14. The risk of violence against the lone worker was listed as a major risk, as well as the difficulty of getting aid and assistance should anything happen, including violent incidents.

Sectors of Employment The likelihood of workplace violence can also be related to sectors of employment.

Health service.

Public transport: −

Buses/Tramways.

−

Overground trains/Railways.

−

Underground trains/Subway.

Licensed premises.

Retail trades.

Government/local:

−

Unemployment benefit offices.

−

Housing offices.

Traffic warden departments.

From this analysis, it is clear that there are many jobs within the above sectors of employment where employees are required to deal directly with members of the public and may therefore be at risk from workplace violence.

Work Activities Outlined below are examples of key activities, and the associated staff, which may be at risk from workplace violence:

Handling money or valuables: −

Cashiers.

−

Delivery staff.

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−

Transport workers.

−

Bank and post office staff.

−

Commissionaires.

−

Security staff.

−

Shop assistants.

Providing care, advice or training: −

Doctors.

−

Nurses.

−

Ambulance staff.

−

Social workers.

−

Housing office staff.

Providing education: −

Teachers.

−

Library staff.

−

Clerical staff.

−

Caretakers.

Carrying out inspection or enforcement duties: −

Traffic wardens.

−

Ticket inspectors.

Working with potentially violent people: −

Prison officers.

−

Security staff.

−

Public house landlords.

−

Mental health workers.

Working alone: −

Home visitors.

−

Taxi drivers.

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Controlling the Risk of Violence Against Employees The Health and Safety Executive in the UK have produced a guidance document (HSG69) to help employers identify and tackle workplace violence. The guidance suggests taking a 4 stage approach:

1 – Finding out if you have a problem. This involves the identification of hazards and problem areas as outlined in the previous section.

Reviewing Cases of Violence In order to address the issue of violence at work, the first stage must be to evaluate whether a problem actually exists. In some workplaces, there may be a perceived threat of violence at work, for example, where staff work alone and there is public access, but no supporting evidence. In other workplaces there may be a real possibility of violence, for example, cash handling on the premises, but the issue has not yet been recognised by management. It is therefore important that all employers at least take steps to try to identify in some way whether or not there is a problem of violence. Depending on the outcome of this first stage, further measures may or may not be necessary. The first simple question to address is whether employees actually interact with the public in the course of their employment. It may be helpful for management to identify the jobs where staff are in direct personal contact with the public. This will produce a list of staff who might possibly be at risk, and also enable a significant number of staff who do not deal directly with the public to be eliminated from the exercise. For some of the jobs listed, it will be obvious that a significant risk of violence does exist, e.g. staff who have to deal with groups of teenagers, or persons who may have been affected by alcohol. However, for other jobs it may be less obvious that there is a problem. The next stage, therefore, should be an evaluation of the scope of the problem. At this point one option might be to introduce a formal system of incident reporting and data collection. This approach will provide hard evidence if a violence problem exists. The disadvantage of this strategy is that it may create needless concern for staff that a violence problem exists and may involve extensive data collection in parts of the organisation where there is no problem.

Informal Survey One way round this is to carry out an informal survey to sound out the views of the workforce. The aim of this is to collect information on aggressive and violent incidents in which employees felt threatened or stressed. This type of survey might involve managers, supervisors, union representatives or health and safety representatives, and enables the collection of a wide range of work-based experiences described by employees themselves to give their personal views on the subject of violence at work. If this type of informal approach gives an indication of a problem with violence to staff in certain sections of the organisation the next stage of the process might then be to initiate formal data collection. However, the conclusion might also be that no real problem of violence has been revealed. This may be due to the fact that potentially violent interactions are being managed or contained. In cases such as these, it would be sufficient to identify the elements of good practice that are responsible for this and to ensure that they are maintained.

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Data Collection Once it has been established that a problem exists with violence at work, it is necessary to introduce a formal reporting system. The existing accident reporting system may provide some information but it is important that data collection provides adequate information to enable preventative measures to be formulated. The following basic information will need to be reported:

Characteristics of the assailant.

Information about the victim.

Details of the incident (before and during).

Details of the situation in which the incident took place.

Details of the outcome.

Classifying Incidents It is important to develop a system of classification of incidents. Once this has been decided, action can be taken, depending on the severity of the incident. Patterns of violence can also be established and this will help employers to take steps to prevent reoccurrences. The system of classification can be simple, such as: fatal or major incidents; less serious incidents requiring first-aid and counselling; an employee feeling at risk.

Prediction Employers should attempt to plan ahead for incidents of violence that might occur in future. This could be done by considering other, similar organisations, and considering the jobs that employers perform, as discussed earlier.

2– Deciding what action to take. This stage requires consideration of who might be harmed, and how; and an evaluation of any existing control measures and whether any more needs to be done. Control strategies will include:

Policies, Procedures and Guidance It is important that staff are given guidance on how to deal with incidents involving violence. This can be developed in accordance with the policy and arrangements that are a component of the action plan. An employer or company’s policy on dealing with violent situations in the workplace can be written into the health and safety policy statement, which will help employees to avoid the risk. Such guidance may extend to techniques designed to give protection or minimise the risk of injury. These may involve self-defence or the use of ‘reasonable’ force to restrain potential assailants. Individuals may legitimately defend themselves or others who are being attacked. For force to be deemed ‘reasonable’, it must be proportionate. It should effectively stop the assault but go no further. It is also important that staff are trained to recognise situations where violence could result (risk factors in the workplace). They should also be trained in the use of interpersonal skills such as recognising the body language of others, and themselves, as a warning to defuse the situation. Support for staff after violent incidents needs to be considered, perhaps including training for managers in counselling skills.

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Working Practices The way certain jobs are carried out can be designed and adjusted so that the risk of violence is reduced. This could include, for example:

Using cheques or forms of credit to avoid staff needing to handle cash.

Avoiding situations where workers are left alone.

If working late is unavoidable, measures must be taken to ensure the worker’s safety, such as arranging a security escort off the premises.

Checking the venues for meetings, as well as the people with whom the employee is meeting, if they are not familiar.

A current UK initiative that London Transport is undertaking to control violence towards London’s bus operatives is to gradually reduce the need for them to handle cash. Measures introduced to reduce the number of people purchasing tickets on board buses include making existing season tickets cheaper and thus more attractive, installing ticket machines at all bus stops – all of which will eventually lead to ‘cash-less’ operatives and thus reduce in part violence towards such operatives. Such schemes are already in full operation in some European countries.

Access for Unauthorised People Access for unauthorised people should be difficult, adequately hindered or visible from a main thoroughfare. Where there is a significant risk from violence, control by swipe card or keypad may be justified. Toughened glass, as used in banks, can also hinder access to, and protect, staff. Access for unauthorised people can also be prevented by the use of security codes and alarm systems.

Suitable Means of Escape Where the possibility of a violent interaction has been identified, it may be necessary to ensure an alternative means of escape to well lit or populated areas.

Property and Furniture Layout and use of property and furniture can help prevent an attack or hinder the attacker’s escape. Therefore, furniture and fittings that are fixed cannot be used as potential weapons, and can also restrict access and egress to and from areas where a violent confrontation might take place. It is also helpful to ensure that objects in the immediate vicinity cannot be used as weapons. Redesigning counters to increase width or height can give staff protection from physical contact. Changing the layout of public waiting areas with better seating, lighting, décor and more regular information about delays can help prevent tension building up in hospital waiting rooms, housing departments and benefit offices, and thereby lessen the chance of confrontation and resulting violence.

Contact Arrangements The risk of violence can be reduced if systems are in place to ensure that any information that is available on the potential for violent behaviour in clients or customers is communicated to staff who have to deal with them. This is a valuable measure in health care situations where client information may be readily available. Where staff need to work or travel alone between a number of workplaces, it is important that information on staff whereabouts and expected time of arrival is recorded and monitored. This

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information should be communicated to the appropriate staff, so that any concerns about personal safety can be quickly followed up. Communication systems such as pagers, mobile phones and personal alarms can be utilised to monitor the location of staff who might be at risk from personal violence and to enable workers to gain assistance if an incident occurs. If it is known or suspected that a person might be at risk from a particular person with a history or record of violence, that person could be accompanied on that particular visit.

Alarms and Response Arrangements Alarm and response arrangements should be made to enable workers who experience difficulties to get assistance. These could include:

Panic buttons, personal alarms, mobile phones, etc. that can be used to enable rapid contact for assistance.

Security measures such as cameras, protective screens and security-coded doors that can be used to monitor staff and prevent unauthorised access.

Lighting to Deter Assailants A common staff concern regarding the potential for violence at work is the existence of poorly lit areas where assailants could hide. Ensuring that external areas, such as car parks and walkways, are well illuminated will deter assailants and reassure staff. This also applies to internal areas, such as storerooms and basements, which are less frequently occupied and therefore are areas where assistance is less likely to be available if a violent incident occurs. The use of Closed Circuit Television in connection with correct lighting could be a further deterrent.

Training Training in employee actions should include:

Training staff to understand and be confident about the causes of violence, to identify early signs of violence, and how to avoid or handle it.

Training staff to use safe systems of work that minimise the risk of violence such as avoiding handling cash in public areas, working alone or walking in high risk areas at night or alone.

Training staff in how to use appropriate interpersonal skills in order to defuse aggression in a potentially violent situation. Such interpersonal skills should include verbal and nonverbal skills.

Victim Support Many of the measures discussed above are aimed at preventing violent incidents from happening in the first place. Experience has shown that preventive measures are unlikely to be 100% effective all the time; this is why complementary mitigation or recovery measures are also used. Employers must, therefore, prepare ahead to deal with the aftermath and effects of violence, both physical and verbal. The response to occurrences must be fast to minimise the effects on the employee involved and in particular to avoid long-term distress to employees. Various steps can be taken to achieve this, including: debriefing, time off work, counselling and legal help.

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Debriefing would involve allowing the person affected to discuss their experience. This should be done as soon as possible and, as well as helping the victim to cope, it may provide valuable information for the employer to avoid such an occurrence in the future. The victim may need time off work to recover from the incident, and although this may differ from person to person, the victim should be encouraged to return to work sooner rather than later as returning to work will become harder as time progresses. At this stage, counselling by a suitable person may be appropriate to help the victim.

3– Take action. This stage is involved with implementation of the selected control strategies.

4 – Check what you have done. This stage requires regular checks of how well the arrangements are working including consultation with employees and where necessary returning to stages 1-3 to ensure that arrangements are adequate for all situations. In addition to this structured action plan approach, there are additional issues that need to be considered at the planning stage of the process to determine the suitability and sufficiency of any control measures. As with any programme designed to manage an occupational health and safety risk, it is important to check that control measures are working.

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Title

Page

Reporting and Investigating Incidents

PURPOSE OF INCIDENT REPORTING AND INVESTIGATION .............................................................................. 3 MORAL ............................................................................................................................................................... 3 LEGAL ................................................................................................................................................................ 4 ECONOMIC ........................................................................................................................................................... 4 METHODS OF ACCIDENT REPORTING AND INVESTIGATION ............................................................................. 7 INTERNAL REPORTING AND RECORDING SYSTEMS ............................................................................................................ 7 ACCIDENT INVESTIGATION RECORDS............................................................................................................................ 7 FORM DESIGN ..................................................................................................................................................... 14 COMPUTER RECORDS ............................................................................................................................................ 15 ACCIDENT INVESTIGATION .............................................................................................................................. 17 OBJECTIVES OF AN INVESTIGATION ........................................................................................................................... 17 INVESTIGATION TEAM ........................................................................................................................................... 17 CONDUCTING THE INVESTIGATION ................................................................................................................. 19 EVIDENCE COLLECTION .......................................................................................................................................... 19 EVIDENCE ANALYSIS AND IDENTIFYING CAUSES ............................................................................................................. 20 TESTING THE EVIDENCE AND HYPOTHESES .................................................................................................................. 22 DRAWING CONCLUSIONS ........................................................................................................................................ 22 ESTABLISHING REMEDIAL ACTIONS TO BE TAKEN ........................................................................................................... 22


BSC International Diploma | Unit 1 Element 1B: Applied Health and Safety Management Study Unit 1B16 | Reporting and Investigating Incidents Learning Outcomes When you have worked through this Study Unit, you will be able to:

1.B.16.1 Explain the purpose of incident reporting and investigation 1.B.16.2 Conduct an accident investigation

Unit 13:

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Purpose of Incident Reporting and Investigation Incident reporting and investigation is a reactive method of managing health and safety within an organisation. However, it still forms an important part of managing health and safety – all accidents and near misses that are reported should be appropriately investigated to determine their root causes. The reporting processes or procedures should enable the most appropriate control measures to be put in place. This will help to ensure that future activities do not place an individual in the same situation where there is the likelihood of injury or ill-health. For an organisation, it will help to ensure that property is not damaged. Ensuring accidents and near misses are reported and appropriately investigated is a form of 'accident prevention', albeit after the initial event. However, the purpose of it is to prevent further injury, ill-health or property damage subsequently occurring. What are the main motives or reasons for preventing accidents within the workplace? There are three main aspects to consider:

Moral (People).

Legal.

Economic (Cost).

Each of these will be discussed in more detail. The following describes the key features behind each aspect, although overlap can be seen between them.

Moral The moral or humanitarian reasons for accident prevention are based on the principal that it is 'wrong' to cause injury or ill-health to another individual by allowing a dangerous environment or activity to exist. This is further compounded by allowing them to work with these hazards and associated risks, without control measures to reduce them to a satisfactory level. There are a number of effects associated with individuals who suffer as a result of an accident, and a list of some of them follows:

Mental strain.

Loss of earnings.

Pain and suffering.

Incapacity from work and impact upon their personal life.

Disability.

Effects on dependants or relatives.

Additional expenditure.

Possible life reduction or loss of life.

When an individual is hurt at work as a result of an accident or due to exposure to substances that have caused ill-health, then the employer could be seen to have failed to ensure the health, safety and welfare of that particular employee. Consequently, the injured party may seek compensation for their 'loss' (their 'loss' could be any of the range of effects listed earlier, as well as some not mentioned). This could also lead into the third area (Economic or Cost) for preventing accidents. Additionally, if there has been a statutory breach of duty and a

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prosecution follows, this can lead to the second purpose for reporting and investigating accidents – the legal purpose.

Legal The legal purpose for reporting and investigating accidents relates to the possibility of prosecution as a result of a failure to comply with specific legislation in part or in full (although this is dependant on the country’s legal system). Employers in the UK have a legal duty to report certain injuries, diseases and dangerous occurrences that are sustained in the workplace. There will also be similar legal requirements in other countries around the world to report accidents, although it must be remembered that health and safety legislation varies from country to country. There may also be legal requirements to carry out investigations into the causes of the accidents and students should make themselves aware of local legislation that applies.

Economic The economic purpose for reporting and investigating accidents relates to the issue of 'cost'. This is the financial consideration for the employer and can be in many forms. Costs can be divided into two distinct categories:

Direct costs.

Indirect costs.

Some of the "direct" and "indirect" costs can be protected or insured against should anything go wrong and a claim is placed to recoup financial losses. Other aspects of both of these costs unfortunately are uninsurable and the organisation itself ultimately bears the cost. Comparisons have been made between insured costs to uninsured costs. The ratio between these costs can be represented by an iceberg, which shows the full cost of accidents including those hidden below the waterline, or unseen in a business.

Insured and Uninsured Costs Iceberg This ratio varies from industry to industry but it typically identifies that for every £1 of insured costs, there is between £8- £36 of uninsured costs.

Direct Costs Some direct costs can be insured against; for instance, damage to buildings or vehicles could be claimed. Often as a result of the claim, though, the insurance upon renewal would increase

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to reflect the employer's claim, or how the market overall has been affected in the last year or so. This results in increased insurance premium. Additional direct costs can affect an organisation. However, they are not insurable, and tend to be in the form of sick pay, overtime payments, repair costs, loss or damage to products. However, if an individual is successful in their claim for damages in a UK civil case, and is awarded compensation for their 'loss', there is insurance that organisations can take out to guard against payouts. This payment would be classed as a direct insured cost.

Indirect Costs Indirect costs can be insured against or be uninsured simply as a result of the nature of the 'cost'. Some examples of indirect insured costs would be the interruption of business activities and product liability. If there was any 'loss' to an organisation following an accident and business was interrupted or products were not saleable as a direct result of the accident, then a claim could be made in light of this to recoup the money lost. Indirect uninsured costs consist of: investigation costs, loss of goodwill (which can not be measured until some time after the event), loss of corporate image or Company branding, and the costs of hiring and training replacement staff. There are a number of indirect costs (both insured and uninsured), which many organisations do not account for. Consequently, organisations can either end up over budget or having budgets depleted due to accounting that has not considered some costs associated with accidents and their follow-ups. These associated costs (insured and uninsured) could include the following: •

Working Time Lost Following an accident, the injured person would initially be given first-aid, and may then be taken to hospital either by ambulance accompanied by a colleague, or taken there directly by a colleague. Both the time taken to treat them, and the initial paper work to be completed, takes an individual away from their normal duties, as does accompanying them or taking them directly to hospital. Time lost from work through accident investigation can affect a number of people ranging from the supervisor or manager of the person involved, to the health and safety department as well as safety representatives of that area. Time will be spent identifying root causes, meeting to discuss potential weak areas and proposing remedial actions or new control measures. The individual injured will be absent initially to recover, and may even have an extended time away from work as a direct result of the nature of the injury or illness. Additional time may be required to attend hospital, visit an occupational health therapist, their GP or even physiotherapy, etc. for follow-ups whilst on the road to recovery.

•

Consequential Loss Consequential loss consists of replacement labour for an injured or ill person in the interim, or even longer term, and which can be part or full time. There may well have been interruptions to the work sequence or control which will mean down time in order to rectify those areas affected, or may even mean new parts need ordering and installing. Individuals at the place of work who become aware of the accident or ill-health often enquire about their colleague's progress and when they might be returning to work. In

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addition, time might be taken to show sympathy in the form of gifts, collections, etc. These actions, although understandable and laudable, all detract from work and have a cost associated with them through loss of working time. Following an accident or ill-health, there is often a drop in the morale of the local workforce which spreads to other workers who become aware of the accident. Some individuals may be involved with aspects of the accident investigation and this can subsequently lead to morale dropping during the investigation and also later, when the root causes become apparent. •

Damage Repair and Replacement Accident repairs can be to the building, plant or equipment affected, and the products may require replacing. The current product being manufactured may have to be scrapped, or a selection of them removed and disposed of. This all amounts to lost revenue. The 'down time' of the area or equipment could ultimately mean the late delivery of an order (perhaps resulting in a penalty) or even the loss of customer.

•

Expenditure During the individual's absence, some form of sick pay would normally be available. As a direct result of being a person short and not having enough manpower, other workers may be required to work additional hours and thus may be paid overtime. A replacement may even be sought from an outside agency, or through a temporary internal move within the company. All of these would constitute costs that had not been accounted for. Following the investigation and root cause analysis, new control measures or parts may be required, which would need to be ordered and then fitted. Additional training as a result of the new work processes or procedures could be required to accompany the new control measures, or may be required regardless of any such measures.

•

Legal Action Depending upon the country, there may be costs associated with follow-up visits from enforcement officers to the site, and also with carrying out further investigation where discussions and meetings take individuals away from their current work. Prosecutions in such countries require meetings with barristers/solicitors and other internal meetings, to define the course of defence. Time spent gathering the relevant information for presentation can be very time consuming. When the case goes to court, individuals from the organisation will be required to attend. They may even be required to give evidence where time will have been spent preparing them for this. Ultimately, if the organisation is found guilty of the statutory breach, then the courts will fine them. In the UK, if a civil claim has been pursued, and the individual is successful, damages will be awarded to them. Both of these costs come from the organisation's revenue and are of an unknown quantity.

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Methods of Accident Reporting and Investigation Internal Reporting and Recording Systems It is important that information is kept for all injuries whether they be serious or not. The safety practitioner needs to design a suitable form to ensure that he or she gets the information needed for investigations. Reporting of near misses requires some careful thought. This could involve a report by the supervisor or some sampling and interview technique.

Accident Book An accident records log (accident book) is an essential tool in collecting accident and incident data. It provides the initial record of the accident, which may then be used as a basis for an investigation. As a minimum, the accident book should contain:

Full name, address and occupation of injured person.

Date and time of the accident.

Place where accident happened.

Cause and nature of injury.

Name, address and occupation of person giving notice, if other than the injured person.

Every entry in an accident book should normally be signed by the injured person to confirm that it is a true account of the circumstances, or if he or she is unable to do so, by some other person acting on the victim's behalf. We consider the use and content of report forms as the basis of accident logs later in this Study Unit, together with the analysis of incident data.

Accident Investigation Records Accident investigation forms are used to provide management with an objective tool for measuring and evaluating safety performance.

Format The form is completed as a record of the investigation but, since the requirements of different work environments are so varied, there is no such thing as a standard report form. Generally, the report form should include the following information:

Name and personal details of the person who had the accident.

Date, day and time of the accident.

Where the accident happened, i.e. department and specific location.

The actual occupation of the person involved.

The job being done at the time.

The nature of the injury or damage.

What inflicted the injury or damage.

Who had control of the cause of the injury or damage.

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What actually happened.

What things caused the accident, i.e. physical conditions and acts of persons.

Immediate remedial action.

Recommendations to prevent the accident in future.

Use of incident data Accident records are useless if they are used only to count accidents. They should be used as a tool to help control the accidents that are causing the injuries and damage. Detailed and thorough study of the records as part of the normal on-going accident prevention programme should yield the following useful information:

The relative importance of the various injury and damage sources.

The conditions, processes, machines and activities that cause the injuries/damage.

The extent of repetition of each type of injury or accident in each operation.

Accident repeaters, i.e. those workers who tend to be repeatedly injured or are involved in more accidents.

How to prevent similar accidents in the future.

Sample Forms The section that follows shows four typical sample forms of the type you are likely to encounter:

Supervisor's Report of Injury.

Incident Investigation Report.

Injury Report Form 1.

Injury Report Form 2.

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Dept:

Name: Date:

Name of victim Date of injury

Age Time

Sex Works No.

Nature of injury

Where and how did accident occur?

Unsafe acts or conditions

Witnesses

Corrective/Remedial action

Recommendations

Supervisor's Report of Injury

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Employee (if involved)

Works No.

Department

Section

Incident Date

Reported Date

DESCRIPTION OF INCIDENT (including location, witnesses, and circumstances surrounding incident)

Actual or possible causal factors ________________________________________________

Corrective/Remedial action

Signature

Date

Supervisor's Name Signature

Date

Incident Investigation Report

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VICTIM:

Name

Works No. ___ Dept Age

Sex

Occupation when injured ______________________________________________________ Was this his/her regular occupation? If not, state regular occupation How long employed?

ACCIDENT:

Date

Time

Place

Description of how accident happened (include name, part, and plant number of machine or tool involved)

Was part of m/c causing accident properly guarded? ________________________________ Type of feed

Type of guard

Was employee following safety rules? ___________________________________________ If not, why not? _____________________________________________________________

Was injury result of lack of ordinary care?

If so, how?

Did some other person cause the accident? If so, how? How could recurrence be prevented? (Continued) Injury Report Form 1

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INJURY:

Describe injury and part of person injured

Did victim resume work after medical attention? If not, was he/she sent home or to hospital? Home or hospital address

WITNESSES:

Give name, number and department:-

Name

Works No.

Department

Name of supervisor in charge of work

ANY OTHER USEFUL INFORMATION: Further description/cause of the accident together with sketch:

Completed by Signature

Position Date

Injury Report Form 1 (Continued)

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Name

Works No.

Dept

Occupation

Date of injury

Time

Supervisor Nature of injury

Immediate cause of injury

Initial treatment

Name of first-aider Signature

Date

Is further treatment required? Yes/No Victim sent home/to hospital? Will injury cause loss of time? Yes/No NATURE OF INJURY WOUNDS:

BURNS:

SITE OF INJURY

laceration

Head

contusion

Face

puncture

Eyes

foreign body

Nose

wet heat (scald)

Teeth

dry heat

Chin

chemical

Ear

friction

Neck

(Continued) Injury Report Form 2

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NATURE OF INJURY SKIN:

SITE OF INJURY

dermatitis

Throat

irritation

Shoulder

rash

Arm

FRACTURE

Elbow

SPRAIN

Wrist

STRAIN

Hand

PAIN

Fingers

POISON

Thumb

OTHER (detail):

Chest Ribs Back Abdomen Hip Groin Leg Thigh Knee Shin Ankle Foot Instep Toe

Injury Report Form 2 (Continued)

Form Design Any incident form should be designed to suit the work situation, and needs to include information that is of use to the safety practitioner. Here are some ideas that are worth taking into account:

The Health and Safety handbook of the Institute of Environmental Officers requires the reporter to state if the cause of the accident is: −

Unsuitable working environment.

−

Physical unsuitability.

−

Lack of knowledge or skill.

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−

Improper attitude.

The American Standards Association requires six accident factors to be stated: −

The agency - the object or substance involved.

−

The agency part.

−

The unsafe mechanical or physical condition.

−

The accident type.

−

The unsafe act.

−

The unsafe personal factor.

UK HSE booklets often identify causes found as a result of a detailed study. Deadly Maintenance was a UK investigation into maintenance accidents, and listed the causes as: Absence of a safe system of work

46%

Defective or inadequate equipment

18%

Human factors or errors

13%

Poor design

4%

Unauthorised activity

5%

Management failure

6%

Not known

8%

Taking some of the above ideas, any accident or injury report form should at least require the person reporting an accident to say whether, in their opinion, the cause was:

An unsuitable working environment.

Lack of a safe system of work.

Unsafe or inadequate equipment.

Lack of effective instruction or supervision.

Unsafe personal factors.

Computer Records The use of the personal computer has revolutionised the storage and manipulation of accident data.

Programs Available The programs that are of most interest are:

Databases.

Spreadsheets.

A database program can be used to store accident data in a set format, then retrieve and analyse it. It can search through the whole of a year's company accident records within a few seconds and give an answer to such questions as:

How many employees had an accident on a Friday?

How many accidents involved a broken arm?

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Who had accidents involving a power press?

A spreadsheet program is rather like a large sheet of graph paper, with many rows and columns, where a number or phrase can be put into each of the spaces. Columns or rows of numbers can be added, or calculations performed, using values in the table. The program can also produce graphs and other pictorial forms of information. These programs can also be combined, with information and data being transferred from one to the other. A large company with a computer department would probably organise their own programs for accident statistics, but there are also a large number of commercial programs for the purpose.

Preparing Data Input It is only possible to retrieve and manipulate data that has been input first. Many programs will accept data directly from the keyboard. The person reporting the injury can be asked a series of questions, the answers to which only involve choosing one item from a list. There are advantages in having a special form completed for the purpose. Restricted access to the computer system maintains security of records. The written record can be retained as an additional safeguard. The form must contain information, such as work area, job type, machinery used, work-inprogress, whether safety precautions were in place, whether personal protective equipment was being worn, etc. Care must be taken in the topics of "cause of injury" and "cause of accident" to avoid confusion and to get information which is useful later. A simple format requiring just a tick next to a statement is preferable.

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Accident Investigation Objectives of an Investigation The objectives of any investigation are to:

Ultimately, prevent re-occurrence.

Enable the root causes of the accident or ill-health to be identified.

Produce clear understanding of the root causes that enables good control measures to be identified in relation to the type of loss that has occurred.

Implement control measures and remedial actions, and thus minimise the opportunity for reoccurrence of a similar accident or ill-health.

In order to achieve the objectives identified above, the first task is to gather information that will aim to determine:

The chain of events leading up to the accident.

The real causes of the accident and any contributing factors that may have affected the scale of the consequences.

Remedial actions required to prevent re-occurrence.

Risk classification.

Breaches of company procedures/policies or statutory requirements.

Whether there are any underlying identifiable trends.

Investigation Team Investigations require a group of individuals who are competent to carry out the tasks required to complete the investigation. Their skills should generally complement the group. The group may typically consist of: a Health and Safety Practitioner, Employee Representative, Supervisor or Manager, and any other individuals who may have specialist knowledge of that activity or area. The size and make up of the group will depend on the nature of the incident. The group described in the previous paragraph would be suitable for a serious incident, such as a fatality. If the incident was less serious, such as a near miss, a supervisor or safety advisor could investigate independently, even though the objective is ultimately the same.

Health and Safety Practitioners or Staff Health and Safety staff can provide assistance and guidance to those involved in the investigation, and will have more experience in how the process should work to achieve the end goal of implementing remedial actions. They would provide support during the investigation process, and would guide individuals through the best methods for accessing information, and where and what the investigating group should focus on. They would play more of a monitoring role, and generally only assist directly when there are areas in which others are less experienced, or should they be unhappy with the local investigation conclusions.

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Supervisors As these individuals are often the person in direct operational control of the area, supervisors should have the responsibility to carry out the initial investigation, as this will often be sufficient to meet the requirements of the situation that has occurred. They will have local knowledge of the workplace conditions, the people involved in the activities, and area. They will have a breadth of information and knowledge that will be important to utilise in the investigation. Supervisors also have the authority to take appropriate action (immediately if necessary) for remedial measures to be implemented. The supervisor should benefit from the outcomes of the investigation through prevention of future accidents or ill-health, which link to direct and indirect costs that affect departments and organisations alike, and cause work disruptions. This should indirectly reduce costs by reducing downtime and damage, and it demonstrates better overall control. Managers More often than not, managers will oversee an investigation and form part of the main group to ensure that the investigation progresses according to plan and proposed timescales, and that remedial actions are not only proposed but implemented. They may be more directly involved due to the severity and nature of the accident or ill-health, or when the incident exceeds the experience or authority of the supervisor dealing with the event.

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Conducting the Investigation The main areas to cover to ensure that an investigation is thorough are:

Evidence collection.

Evidence analysis.

Testing the evidence.

Drawing conclusions.

Identifying causes.

Establish remedial actions to be taken.

Evidence Collection Evidence collection covers three main aspects:

Witnesses and the scene.

Machinery, equipment, the environment and the people.

Documents and procedural controls.

Witnesses and the Scene In order to gather suitable information from the scene, the first action should be 'getting the bigger picture'. In order to do this, it is important to note exactly what is seen on first arrival. Taking photos is a good way to capture this information, and they can be used as supporting evidence should it be required at a later date, or simply to capture the scene accurately rather than trying to imagine what a witness really 'saw' from their description of the scene. As much information about the scene as possible should be gathered, and it may be necessary to make sure that it remains untouched until such time that all the required information has been gathered. If required, the area should be cordoned off. Only then should items be removed for repair or replacement. Witnesses should be interviewed separately, preferably on site. They should be allowed to go through how they saw the sequence of events occurring. Notes must be taken as the interview progresses, and they will provide key information. The emphasis should be on 'open' questions that allow the witness to provide their version of events. Interviewers or investigators should clarify what they have been told by feeding back what has been said to ensure a clear understanding and representation of the facts has taken place. If appropriate, use drawings or the photos that were taken, to clarify or aid explanation of the situation. At all times, keep the lines of communication open and, when the interview has finished, ensure that witnesses can contact interviewers or investigators should they remember anything additional.

Equipment, Plant, Machinery and the Work Area The types of materials and substances that were originally chosen for use in the activity should be identified. It would then be necessary to identify how they should have been used and, finally, how they were actually used. When collecting evidence concerning the equipment and machinery, it would be necessary to consider whether the items were:

Suitable for the intended task or activity.

Correctly maintained.

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Properly used by an authorised, competent person.

Stored correctly to minimise defects, etc.

It is important that the accident scene is left exactly as it was at the time of the accident. This is especially important if accurate notes are to be taken, and the environment precisely considered. This will help to determine whether or not the environment was one of the factors that contributed to the event. It is also important to visit an accident scene promptly, as transient conditions may have changed, or even gone, if too much time elapses. This could make the difference between some conditions being recorded or missed. All transient conditions should be noted, for example, fumes and wet floors, and checked against witness statements to clarify, or for inclusion, if they have not been previously noticed. The suitability of environmental conditions within the work area should to be taken into account. This covers a wide range of aspects, some of which are: lighting, temperature, noise, ventilation, floor conditions, access and egress, working at height, confined or restricted space. Finally, it is important to identify the competency level of the people using the equipment or performing the task, and to determine whether they were authorised to do so. It is also essential to find out whether they adhered to the procedures or not, as well as whether they were provided with sufficient information to be able to make a sound judgement for that task and, if they were less experienced, whether they were properly supervised. There may have been 'human factors' that affected the individual's ability to perform his or her role, or function appropriately. If so, how did these human factors contribute to the occurrence of the accident or ill-health. Finally, it is essential to ensure that the information gathered is recorded as it becomes known, and to make sure that it is logically and clearly recorded for anyone to understand and follow.

Documents and Procedural Controls Organisations have many types of documents that may be useful in understanding how operations should work. However, only a certain number of these will be specifically relevant in establishing the required facts in relation to an accident investigation. Careful choice of the documents and procedures to be included will need to be made and should consist of at least:

Training records (past and present).

Maintenance records.

Inspection and audit records.

Appropriate test certificates and maintenance logs (daily, weekly).

Previous accident records.

Procedures or work practices, safe systems of work, permit systems, standard operating procedures should be reviewed and then compared to what course of action actually took place to operate the equipment or perform that task.

Evidence Analysis and Identifying Causes Analysing all the documentation, witness information, photo procedures, processes, etc. is the second step in the process of accident investigation. It must be remembered that accidents are rarely as a result of a single event; they are normally the result of multi-causal events. This must be borne in mind when comparing all the information and working through the process to identify causes.

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When the evidence collected is analysed, it should be placed into the categories that will aid the next stage of identifying causes. There are two types of causes –immediate and underlying. Immediate causes according to Heinrich's theory are the unsafe act of individuals and the existence of unsafe conditions. The latter tend to be caused by poor job factors, such as substandard conditions leading to unsafe conditions, and poor personal factors, such as substandard performance leading to unsafe acts. Some examples of immediate causes of unsafe acts are:

Working without authority.

Removing safeguards.

Ignoring instructions and procedures.

Unauthorised servicing.

Horseplay.

Using defective equipment.

Some examples of immediate causes of unsafe conditions are:

Missing guards.

Excessive noise.

Too little or too much light.

Lack of ventilation.

Poor housekeeping.

Fire hazards.

Underlying causes of accidents are generally thought to be as a result of poor job factors or poor personal factors that are ultimately caused by lack of management control. Some examples of basic causes, such as job factors, are:

Poor supervision.

Wear and tear.

Inadequate maintenance.

Inadequate tools and equipment.

Inadequate engineering.

Some examples of underlying causes, such as personal factors, are:

Lack of knowledge or experience.

Improper motivation.

Inadequate physical/mental ability.

Physical/mental stress.

The accident process is often referred to as a series of dominoes and, as each one falls, it impacts on another domino and causes that one to fall, and so on until there is the misfortune of an accident or ill-health to occur. We discussed Heinrich's Accident Sequence and Domino Sequence in detail in Study Unit 1A1. It would be useful to read that information again now in conjunction with the present topic.

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Testing the Evidence and Hypotheses It is essential to be certain of the validity of any data gathered as evidence. This means double-checking issues such as measurements and supporting documents, because any conclusions drawn will be based on this. It is natural for people to jump to conclusions based on little evidence. We do this all the time in making judgments about other people or situations. The challenge of a thorough, objective and robust investigation process is to retain an open mind about possibilities. Allow the evidence to speak for itself, and don’t try to force it to fit a preconceived theory, decided upon before the investigation even commenced. As we have seen, to establish root causes requires a certain amount of extrapolation beyond available data, and interpolation between sets of data. This is a repetitive process. In gathering the data, we begin to formulate a hypothesis of what actually happened. Of course, in the early stages there will be many gaps in the knowledge that we initially fill with reasonable assumptions. As more data comes in, we test and refine the hypothesis, and the assumptions that we make. This means making sure that the evidence we have fully supports what we think happened in the way it happened. In order to do this, we try and piece together the sequence of events. The hypothesis must stand up to critical examination. This may even involve conducting a few laboratory tests to see if things behave in the way we presume. This could involve, for example, doing an experiment to test whether chemicals ‘A’ and ‘B’ react dangerously under specific conditions of temperature and pressure. It may involve a complex modelling, simulation or calculation exercise. The ultimate test of the hypothesis would be if someone could reproduce the accident by following exactly all the steps in the hypothesis. This is not always possible or desirable, depending on the scale of the loss, but it may be possible to demonstrate some aspects in this way.

Drawing Conclusions We may have several ideas of exactly what happened during the accident, and the possible causes. At some point, these must be drawn together to conclude - that is, give a considered opinion based on the facts - what we think is the most likely scenario. This means critically weighing up the evidence. Once we have done this, it becomes clearer as to what precisely can be done to prevent such an accident happening again.

Establishing Remedial Actions to Be Taken When the immediate and basic causes have been identified and it is clear which pieces of evidence fall into which category, and key causes have been established, it is possible to begin to identify remedial actions and various solutions could be proposed. There may already be some control measures in place and these will need to be compared to the new proposals. It will be necessary to ensure that the correct level of control is ultimately in place. Remedial controls should include: lowering the likelihood of occurrence and reducing the potential severity of loss. Remedial actions can be divided into two types:

Permanent/long term.

Temporary/short terms.

It is important that short or temporary remedial actions are taken immediately or very promptly, and permanent or long-term remedial actions should be taken as soon as possible. Some permanent actions may require equipment or parts to be purchased, and so may have a

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delivery delay which must be accounted for when deciding the most appropriate action to take and the order in which to take it. All remedial actions taken, irrespective of their duration, must be recorded to show the course of action taken and the timescales for them remaining in place, prior to a review or to being replaced by long term solutions. Remedial actions can range from physical methods, documentation updates and control, through to maintenance programmes, and training and information being provided with management support. Some examples of physical methods are: improved physical safeguards; upgrading local exhaust ventilation to HEPA filtration; providing mechanical handling aids; and personal protective equipment. Some examples of documentation updates and control are: updated safe systems of work and work practices, procedures, updating standards and policies, and introducing monitoring and auditing systems. Implementation, analysis and review are the best methods to test how robust, effective, and suitable and sufficient the proposed and implemented remedial measures really are. A programme must be drawn up by identified, responsible individuals to ensure that all elements of remedial actions are implemented. This process must be regularly followed up to ensure that it does actually take place and that the remedial actions are implemented on time. Follow-up actions should be identified and must take place to clarify whether the remedial actions are appropriate in practice, and whether they are being utilised. This part is particularly important to identify any new hazards that have arisen as a result of the new controls being implemented. The review process should not take place once all the remedial actions are in place, but should be a continuing process, both through the course of implementation and for some time afterwards to really establish the effectiveness of the new control measures. Reviewing the performance frequently enables the organisation to ensure that the risks have been suitably and sufficiently controlled.

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Course Notes - 1B

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