REPORT ON SAFETY MEASURES IN CHEMICAL PROCESS INDUSTRIES
TABLE OF CONTENTS 1.Introduction ..........................................................................................6 1.1.SafetyPrograms...............................................................................7 1.2. Engineering Ethics.....................................................................8 1.2.1. Fundamental principles........................................................8 1.2.2. Fundamental canons.............................................................8 2.HISTORY..........................................................................................9 1
2.1. List of Industrial disasters................................................................9 2.2. DISASTER STATISTICS.................................................................10 2.2.1. Four Major disasters:..............................................................11 2.2.1.1. Flixborough accident..................................................11 2.2.1.2. Bhopal Gas Tragedy......................................................12 2.2.1.3. The Seveso disaster........................................................14 2.2.1.4. The Texas Tragedy..........................................................15 3.Accident and Loss Statistics.........................................................................16 4.Process safety................................................................................................20 4.1 The Process of risk analysis.....................................................................20 4.2 Definition of QRA....................................................................................22 4.3 Misconceptions about QRA......................................................................23 4.4 Criteria for electing to use QRA................................................................24 5.Legislation and Law.........................................................................................30 5.1. What health and safety law requires.......................................................30 5.2. Action on health and safety: Options.......................................................30 5.2.1. Guidance....................................................................................31 5.2.2. Approved Codes of Practice........................................................31 5.2.3. Regulations................................................................................32 5.3. How regulations apply............................................................................32 5.4. What next? .........................................................................................33 5.5. Some important pieces of health and safety .........................................33 6. Recent Developments..................................................................................35 6.1. 25 Years after the Bhopal Gas Disaster...............................................35 2
6.1.1. Changes made in USA:..................................................................35 6.1.2. Changes Made in India:.................................................................35 6.2. Recommendations to improve chemical process safety management in India:..................................................................................................................36 7. References.......................................................................................................37
LIST OF FIGURES Figure 1.1 The ingredients of a successful safety program.................................7 Figure 2.2.1.1. A failure of a temporary pipe caused Flixborough accident...11 Figure 2.2.1.2. Reaction of the methyl isocyanate route used at Bhopal.........13 Figure 2.2.1.4. Polyethylene plant settling leg and product take off system...15 3
Figure 4.1.(a) Elements of risk management.....................................................21 Figure 4.1.(b) Elements of risk analysis............................................................21 Figure 4.2. The process of risk analysis.............................................................22 Figure 4.4. Decision criteria for selecting QRA................................................26 Figure 4.4. Decision criteria for selecting QRA (cont.)....................................27
LIST OF TABLES Table 2.2. Disaster Statistics..............................................................................10 Table 3.1 Accident Statistics for Selected Industries........................................18 Table 3.2. Fatality Statistics for Common Nonindustrial Activities..................18 Table 4.4. Classical Limitations of QRA........................................................23
Chapter 1 Introduction In 1987, Robert M. Solow, an economist at the Massachusetts Institute of Technology, received the Nobel Prize in economics for his work in determining the sources of economic growth. Professor Solow concluded that the bulk of an economy‘s growth is the result of technological advances. It is reasonable to conclude that the growth of an industry is also dependent on technological advances. This is especially true in the chemical industry, which is entering an era of more complex processes: higher pressure, more reactive chemicals, and 4
exotic chemistry. More complex processes require more complex safety technology. Many industrialists even believe that the development and application of safety technology is actually a constraint on the growth of the chemical industry. As chemical process technology becomes more complex, chemical engineers will need a more detailed and fundamental understanding of safety. H.H. Fawcett said, ―To know is to survive and to ignore fundamentals is to court disaster.‖Since 1950, significant technological advances have been made in chemical process safety. Today, safety is equal in importance to production and has developed into a scientific discipline that includes many highly technical and complex theories and practices. Examples of the technology of safety include • hydrodynamic models representing two-phase flow through a vessel relief • dispersion models representing the spread of toxic vapour through a plant after a release And mathematical techniques to determine the various ways that processes can fail and the probability of failure. Recent advances in chemical plant safety emphasize the use of appropriate technological tools to provide information for making safety decisions with respect to plant design and operation. The word ―safety‖ used to mean the older strategy of accident prevention through the use of hard hats, safety shoes, and a variety of rules and regulations. The main emphasis was on worker safety. Much more recently, ―safety‖ has been replaced by ―loss prevention.‖ This term includes hazard identification, technical evaluation, and the design of new engineering features to prevent loss. The subject of this text is loss prevention, but for convenience, the words ―safety‖ and ―loss prevention‖ will be used synonymously throughout. Safety, hazard, and risk are frequently-used terms in chemical process safety. Their definitions are • Safety or loss prevention: the prevention of accidents through the use of appropriate technologies to identify the hazards of a chemical plant and eliminate them before an accident occurs. •Hazard: a chemical or physical condition that has the potential to cause damage to people, property, or the environment. • Risk: a measure of human injury, environmental damage, or economic loss in terms of both the incident likelihood and the magnitude of the loss or injury. Chemical plants contain a large variety of hazards. First, there are the usual mechanical hazards that cause worker injuries from tripping, falling, or moving equipment. Second, there are chemical hazards. These include fire and explosion hazards, reactivity hazards, and toxic hazards. As will be shown later, chemical plants are the safest of all manufacturing facilities. However, the potential always exists for an accident of catastrophic proportions.
1.1 Safety Programs A successful safety program requires several ingredients. These ingredients are • System •Attitude • Fundamentals
5
• Experience • Time • You
Fig. 1.1 The ingredients of a successful safety program. First, the program needs a system (1) to record what needs to be done to have an outstanding safety program, (2) to do what needs to be done, and (3) to record that the required tasks are done. Second, the participants must have a positive attitude. This includes the willingness to do some of the thankless work that is required for success. Third, the participants must understand and use the fundamentals of chemical process safety in the design, construction, and operation of their plants. Fourth, everyone must learn from the experience of history or be doomed to repeat it. It is especially recommended that employees (1) read and understand case histories of past accidents and (2) ask people in their own and other organizations for their experience and advice. Fifth, everyone should recognize that safety takes time. This includes time to study, time to do the work, time to record results (for history), time to share experiences, and time to train or be trained. Sixth, everyone (you) should take the responsibility to contribute to the safety program. A safety program must have the commitment from all levels within the organization. Safety must be given importance equal to production. The most effective means of implementing a safety program is to make it everyone‘s responsibility in a chemical process plant. The older concept of identifying a few employees to be responsible for safety is inadequate by today‘s standards. All employees have the responsibility to be knowledgeable about safety and to practice safety. It is important to recognize the distinction between a good and an outstanding safety program. •A good safety program identifies and eliminates existing safety hazards.
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•An outstanding safety program has management systems that prevent the existence of safety hazards. A good safety program eliminates the existing hazards as they are identified, whereas an outstanding safety program prevents the existence of a hazard in the first place. The commonly used management systems directed toward eliminating the existence of hazards include safety reviews, safety audits, hazard identification techniques, checklists, and proper application of technical knowledge.
1.2 Engineering Ethics Most engineers are employed by private companies that provide wages and benefits for their services. The company earns profits for its shareholders, and engineers must provide a service to the company by maintaining and improving these profits. Engineers are responsible for minimizing losses and providing a safe and secure environment for the company‘s employees. Engineers have a responsibility to themselves, fellow workers, family, community, and the engineering profession. 1.2.1 Fundamental principles Engineers shall uphold and advance the integrity, honor, and dignity of the engineering profession by 1. using their knowledge and skill for the enhancement of human welfare; 2. being honest and impartial and serving with fidelity the public, their employers, and clients; 3. striving to increase the competence and prestige of the engineering profession.
1.2.2 Fundamental canons 1. Engineers shall hold paramount the safety, health, and welfare of the public in the performance of their professional duties. 2. Engineers shall perform services only in areas of their competence. 3. Engineers shall issue public statements only in an objective and truthful manner. 4. Engineers shall act in professional matters for each employer or client as faithful agents or trustees, and shall avoid conflicts of interest. 5. Engineers shall build their professional reputations on the merits of their services.
Chapter 2 HISTORY 2.1 List of Industrial disasters:
September 21, 1921: Oppau explosion in Germany. Occurred when a tower silo storing 4,500 tonnes of a mixture of ammonium sulfate and ammonium nitrate
7
fertilizer exploded at a BASF plant in Oppau, now part of Ludwigshafen, Germany, killing 500–600 people and injuring about 2,000 more. 1932-1968: The Minamata disaster was caused by the dumping of mercury compounds in Minamata Bay, Japan. The Chisso Corporation, a fertilizer and later petrochemical company, was found responsible for polluting the bay for 37 years. It is estimated that over 3,000 people suffered various deformities, severe mercury poisoning symptoms or death from what became known as Minamata disease. April 16, 1947: Texas City Disaster, Texas. At 9:15 AM an explosion occurred aboard a docked ship named the Grandcamp. The explosion, and subsequent fires and explosions, is referred to as the worst industrial disaster in America. A minimum of 578 people lost their lives and another 3,500 were injured as the blast shattered windows from as far away as 25 mi (40 km). Large steel pieces were thrown more than a mile from the dock. The origin of the explosion was fire in the cargo on board the ship. Detonation of 3,200 tons of ammonium nitrate fertilizer aboard the Grandcamp led to further explosions and fires. The fertilizer shipment was to aid the struggling farmers of Europe recovering from World War II. Although this industrial disaster was one of the largest involving ammonium nitrate, many others have been reported including a recent one in North Korea. 1948: A chemical tank wagon explosion within the BASF's Ludwigshafen, Germany site caused 207 fatalities. June 1, 1974: Flixborough disaster, England. An explosion at a chemical plant near the village of Flixborough kills 28 people and seriously injures another 36. July 10, 1976: Seveso disaster, in Seveso, Italy, in a small chemical manufacturing plant of ICMESA. Due to the release of dioxins into the atmosphere and throughout a large section of the Lombard Plain, 3,000 pets and farm animals died and, later, 70,000 animals were slaughtered to prevent dioxins from entering the food chain. In addition, 193 people in the affected areas suffered from chloracne and other symptoms. The disaster lead to the Seveso Directive, which was issued by the European Community and imposed much harsher industrial regulations. December 3, 1984: The Bhopal disaster in India is the largest industrial disaster on record. A faulty tank containing poisonous methyl isocyanate leaked at a Union Carbide plant. About 20,000 people died and about 570,000 suffered bodily damage.[1] The disaster caused the region's human and animal populations severe health problems to the present. November 1, 1986: The Sandoz disaster in Schweizerhalle, Switzerland, releasing tons of toxic agrochemicals into the Rhine. June 28, 1988: Auburn, Indiana, improper mixing of chemicals kills four workers at a local metal-plating plant in the worst confined-space industrial accident in U.S. history; a fifth victim died two days later.[2] October 23, 1989: Phillips Disaster. Explosion and fire killed 23 and injured 314 in Pasadena, Texas. Registered 3.5 on the Richter scale.
2.2 DISASTERS Number of Origin of accident
Year
Date
Location
Products involved
Bulk cargo handling terminal
1997
02.01
Mumbai
Sulphur
Explosion
1983
29.09
Dhulwari
Gasoline
Deaths
Injured
Evacuated
41
>100
..
8
Explosion (warehouse)
1992
29.04
New Delhi
Chemicals
43
20
Fire
1983
03.11
Dhurabari
Oil
76
>60
-
Fire
1985
01.11
Padaval
Gasoline
>43
82
..
Fire at a chemical store 1994
13.11
New Delhi
Toxic cloud (chemicals)
Fire in refinery
1988
09.11
Bombay
Oil
35
16
..
Leakage
1984
03.12
Bhopal
Methyl isocyanate
2800
50 000
200 000
Leakage
1989
05.05
Britannia Chowk
Chlorine
-
200
..
Leakage
1990
05.11
Nagothane
Ethane and propane
32
22
Leakage
1988
22.12
Jhurkully
Sulphur dioxide
-
500
..
Leakage
1989
17.01
Bhatinda
Ammonia
-
500
..
Leakage
1987
24.06
Bhopal
Ammonia
leakage (transport accident)
1997
21.01
Bhopal
Ammonia
400
Leakage from a pipeline
1991
02.12
Calcutta
Chlorine
200
Leakage in an Ice Factory
1990
02.07
Lucknow
Ammonia gas
200
Plant explosion
1980
03.05
Mandir Asod
Explosives
Refinery fire
1997
14.09
Vishakapatnam
Release
1985
14.05
Cochin
Release
1985
04.12
Transport
1985
09.08
Transport accident
1994
Transport accident
500
200 000
50
..
-
34
31
150000
Hexacyclo-pentadiene
-
200
..
New Delhi
Sulphuric acid
1
340
>10
Tamil Nadu
Gasoline
60
..
..
02.01
Thane District
Chlorine gas
4
298
1991
02.01
New Bombay
Ammonia gas
1
150
Transport accident
1995
12.03
Madras
Fuel
~100
23
Transport accident
1995
02.12
Maharashtra
Ammonia gas
Transport accident (leakage)
1991
02.11
Medran
Inflammable liquid
93
25
India
Chlorine
1
150
1985
2 000
-
Table 2.2. Disaster Statistics
2.2.1. Four Major disasters: The study of case histories provides valuable information to chemical engineers involved with safety. This information is used to improve procedures to prevent similar accidents in the future. The four most cited accidents (Flixborough, England; Bhopal, India; Seveso, Italy; and Pasadena, Texas) are presented here. All these accidents had a significant impact on public perceptions and the chemical engineering profession that added new emphasis and standards in the practice of safety. 9
2.2.1.1. Flixborough accident The Flixborough accident is perhaps the most documented chemical plant disaster. The British government insisted on an extensive investigation .The accident at Flixborough, England, occurred on a Saturday in June 1974. Although it was not reported to any great extent in the United States, it had a major impact on chemical engineering in the United Kingdom. As a result of the accident, safety achieved a much higher priority in that country .The Flixborough Works of Nypro Limited was designed to produce 70,000 tons per year of caprolactam, a basic raw material for the production of nylon. The process uses cyclohexane ,Flixborough, EnglandThe accident at Flixborough, England, occurred on a Saturday in June 1974. Although itwas not reported to any great extent in the United States, it had a major impact on chemical engineering in the United Kingdom. As a result of the accident, safety achieved a much higher priority in that country .The Flixborough Works of Nypro Limited was designed to produce 70,000 tons per year of caprolactam, a basic raw material for the production of nylon. The process uses cyclohexane, which has properties similar to gasoline. Under the process conditions in use at Flixborough (155°C and 7.9 atm), the cyclohexane volatilizes immediately when depressurized to atmospheric conditions.
Fig. 2.2.1.1 A failure of a temporary pipe section replacing reactor 5 caused the Flixborough accident.
The process where the accident occurred consisted of six reactors in series. In these reactors cyclohexane was oxidized to cyclohexanone and then to cyclohexanol using injected air in the presence of a catalyst. The liquid reaction mass was gravity-fed through the series of reactors. Each reactor normally contained about 20 tons of cyclohexane. Several months before the accident occurred, reactor 5 in the series was found to be leaking. Inspection showed a vertical crack in its stainless steel structure. The decision was made to remove the reactor for repairs. An additional decision was made to continue operating by connecting reactor 4 directly to reactor 6 in the series. The loss of the reactor would reduce the yield but would enable continued production because unreacted cyclohexane is separated and recycled at a later stage.The feed pipes connecting the reactors were 28 inches in diameter. Because only 20-inchpipe stock was available at the plant, the connections to reactor 4 and reactor 6 were made using flexible bellows-type piping, as shown in Figure 1-10. It is hypothesized that the bypass pipesection ruptured because of inadequate support and overflexing of the pipe section as a result of internal reactor pressures. Upon rupture of the bypass, an estimated 30 tons of cyclohexane volatilized and formed a large vapour cloud. The cloud was ignited by an unknown source an estimated 45 seconds after the release. The resulting explosion levelled the entire plant facility, including the administrative offices . Twenty-eight people died, and 36 others were injured. Eighteen of these fatalities occurred in the main control room when 10
the ceiling collapsed. Loss of life would have been substantially greater had the accident occurred on a weekday when the administrative offices were filled with employees. Damage extended to 1821 nearby houses and 167 shops and factories. Fifty-three civilians were reported injured. The resulting fire in the plant burned for over 10 days. This acident could have been prevented by following proper safety procedures. First, the bypass line was installed without a safety review or adequate supervision by experienced engineering personnel. The bypass was sketched on the floor of the machine shop using chalk! Second, the plant site contained excessively large inventories of dangerous compounds. This included 330,000 gallons of cyclohexane, 66,000 gallons of naphtha, 11,000 gallons of toluene,26,400 gallons of benzene, and 450 gallons of gasoline. These inventories contributed to the fires after the initial blast. Finally, the bypass modification was substandard in design. As a rule, any modifications should be of the same quality as the construction of the remainder of the plant.
2.2.1.2 Bhopal Gas Tragedy The Bhopal, India, accident, on December 3, 1984, has received considerably more attention than the Flixborough accident. This is due to the more than 2000 civilian casualties that resulted. The Bhopal plant is in the state of Madhya Pradesh in central India. The plant was partially owned by Union Carbide and partially owned locally. The nearest civilian inhabitants were 1.5 miles away when the plant was constructed. Because the plant was the dominant source of employment in the area, a shantytown eventually grew around the immediate area. The plant produced pesticides. An intermediate compound in this process is methyl iso-cyanate (MIC). MIC is an extremely dangerous compound. It is reactive, toxic, volatile, and flammable. The maximum exposure concentration of MIC for workers over an 8-hour period is 0.02 ppm (parts per million). Individuals exposed to concentrations of MIC vapours above 21ppmexperience severe irritation of the nose and throat. Death at large concentrations of vapour is due to respiratory distress.MIC demonstrates a number of dangerous physical properties. Its boiling point at atmospheric conditions is 39.1°C, and it has a vapour pressure of 348mmHg at 20°C.The vapour is about twice as heavy as air, ensuring that the vapours will stay close to the ground once released.MIC reacts exothermically with water. Although the reaction rate is slow, with inadequate cooling the temperature will increase and the MIC will boil. MIC storage tanks are typically refrigerated to prevent this problem. The unit using the MIC was not operating because of a local labour dispute. Somehow a storage tank containing a large amount of MIC became contaminated with water or some other substance. A chemical reaction heated the MIC to a temperature past its boiling point. The MIC vapours travelled through a pressure relief system and into a scrubber and flare system installed to consume the MIC in the event of a release. Unfortunately, the scrubber and flare systems were not operating, for a variety of reasons. An estimated 25 tons of toxic MIC vapour was released. The toxic cloud spread to the adjacent town, killing over 2000 civilians and injuring an estimated 20,000 more. No plant workers were injured or killed. No plant equipment was damaged. The exact cause of the contamination of the MIC is not known. If the accident was caused by a problem with the process, a well-executed safety review could have identified the problem. The scrubber and flare system should have been fully operational to prevent the release. Inventories of dangerous chemicals, particularly intermediates, should also have been minimized. 11
Fig. 2.2.1.2. The upper reaction is the methyl isocyanate route used at Bhopal. The lower reaction suggests an alternative reaction scheme using a less hazardous intermediate.
The reaction scheme used at Bhopal is shown at the top of Figure 2.2.1.2 and includes the dangerous intermediate MIC. An alternative reaction scheme is shown at the bottom of the figure and involves a less dangerous chloroformate intermediate. Another solution is to redesign the process to reduce the inventory of hazardous MIC. One such design produces and consumes the MIC in a highly localized area of the process, with an inventory of MIC of less than20 pounds.
2.2.1.3. The Seveso disaster Seveso is a small town of approximately 17,000 inhabitants, 15 miles from Milan, Italy. The plant was owned by the Icmesa Chemical Company. The product was hexachlorophene, 12
abactericide, with trichlorophenol produced as an intermediate. During normal operation, a small amount of TCDD (2,3,7,8-tetrachlorodibenzoparadioxin) is produced in the reactor as an undesirable side-product. TCDD is perhaps the most potent toxin known to humans. Animal studies have shown TCDD to be fatal in doses as small as 10-9 times the body weight. Because TCDD is also insoluble in water, decontamination is difficult. Nonlethal doses of TCDD result in chloracne, an acne-like disease that can persist for several years. On July 10, 1976, the trichlorophenol reactor went out of control, resulting in a higher than normal operating temperature and increased production of TCDD. An estimated 2 kg of TCDD was released through a relief system in a white cloud over Seveso. A subsequent heavy rain washed the TCDD into the soil. Approximately 10 square miles were contaminated. Because of poor communications with local authorities, civilian evacuation was not started until several days later. By then, over 250 cases of chloracne were reported. Over600 people were evacuated, and an additional 2000 people were given blood tests. The most severely contaminated area immediately adjacent to the plant was fenced, the condition it remains in today. TCDD is so toxic and persistent that for a smaller but similar release of TCDD in Duphar, India, in 1963 the plant was finally disassembled brick by brick, encased in concrete and dumped into the ocean. Less than 200 g of TCDD was released, and the contamination was confined to the plant. Of the 50 men assigned to clean up the release, 4 eventually died from the exposure. The Seveso and Duphar accidents could have been avoided if proper containment systems had been used to contain the reactor releases. The proper application of fundamental engineering safety principles would have prevented the two accidents. First, by following proper procedures, the initiation steps would not have occurred. Second, by using proper hazard evaluation procedures, the hazards could have been identified and corrected before the accidents occurred. 2.2.1.4. The Texas Tragedy A massive explosion in Pasadena, Texas, on October 23, 1989, resulted in 23 fatalities,314 injuries, and capital losses of over $715 million. This explosion occurred in a high-density polyethylene plant after the accidental release of 85,000 pounds of a flammable mixture containing ethylene, isobutane, hexane, and hydrogen. The release formed a large gas cloud instantaneously because the system was under high pressure and temperature. The cloud was ignited about 2 minutes after the release by an unidentified ignition source. The damage resulting from the explosion made it impossible to reconstruct the actual accident scenario. However, evidence showed that the standard operating procedures were not appropriately followed. The release occurred in the polyethylene product takeoff system, as illustrated in Fig
13
Figure 2.2.1.4. Polyethylene plant settling leg and product takeoff system.
Usually the polyethylene particles (product) settle in the settling leg and are removed through the product takeoff valve. Occasionally, the product plugs the settling leg, and the plug is removed by maintenance personnel. The normal and safe procedure includes closing the DEMCO valve, removing the air lines, and locking the valve in the closed position. Then the product takeoff valve is removed to give access to the plugged leg. The accident investigation evidence showed that this safe procedures not followed; specifically, the product take off valve was removed, the DEMCO valve was in the open position, and the lockout device was removed. This scenario was a serious violation of wellestablished and well-understood procedures and created the conditions that permitted the release and subsequent explosion.TheOSHAinvestigation13 found that (1) no process hazard analysis had been performed in the polyethylene plant, and as a result, many serious safety deficiencies were ignored or overlooked; (2) the single-block (DEMCO) valve on the settling leg was not designed to fail to a safe closed position when the air failed; (3) rather than relying on a single-block valve, a double-block-and-bleed valving arrangement or a blind flange after the single-block valve should have been used; (4) no provision was made for the development, implementation, and enforcement of effective permit systems (for example, line opening); and (5) no permanent combustible gas detection and alarm system was located in the region of the reactors.
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Chapter 3 Accident and Loss Statistics Accident and loss statistics are important measures of the effectiveness of safety programs. These statistics are valuable for determining whether a process is safe or whether a safety procedure is working effectively. Many statistical methods are available to characterize accident and loss performance. These statistics must be used carefully. Like most statistics they are only averages and do not reflect the potential for single episodes involving substantial losses. Unfortunately, no single method is capable of measuring all required aspects. The three systems considered here are •OSHA incidence rate, • fatal accident rate (FAR), and • fatality rate, or deaths per person per year. •OSHA incidence rate, • fatal accident rate (FAR), and • fatality rate, or deaths per person per year. All three methods report the number of accidents and/or fatalities for a fixed number of workers during a specified period. OSHA stands for the Occupational Safety and Health Administration of the United States government. OSHA is responsible for ensuring that workers are provided with a safe working environment. The OSHA incidence rate is based on cases per 100 worker years. A worker year is assumed to contain 2000 hours (50 work weeks/year 40 hours/week). The OSHA incidence rate is therefore based on 200,000 hours of worker exposure to a hazard. The OSHA incidence rate is calculated from the number of occupational injuries and illnesses and the total number of employee hours worked during the applicable period. The following equation is used:
OSHA incidence rate =
(Number of injuries and illnesses x 200,000)/( Total hours worked
(based on injuries and illness)
by all employees during period covered)
An incidence rate can also be based on lost workdays instead of injuries and illnesses. For this case OSHA incidence rate (based on lost workdays)
=
(Number of lost workdays x 200,000)/( Total hours worked by all employees during period covered )
The FAR is used mostly by the British chemical industry. This statistic is used here because there are some useful and interesting FAR data available in the open literature. The FAR 15
reports the number of fatalities based on 1000 employees working their entire lifetime. The employees are assumed to work a total of 50 years. Thus the FAR is based on 108working hours. The resulting equation is the definition of a lost workday is given in Table 1-2. The OSHA incidence rate provides information on all types of work-related injuries and illnesses, including fatalities. This provides a better representation of worker accidents than systems based on fatalities alone. For instance, a plant might experience many small accidents with resulting injuries but no fatalities. On the other hand, fatality data cannot be extracted from the OSHA incidence rate without additional information.
FAR = (No. of fatalities x 108 )/(Total hours worked by all employees during period covered) The last method considered is the fatality rate or deaths per person per year. This system is independent of the number of hours actually worked and reports only the number of fatalities expected per person per year. This approach is useful for performing calculations on the general population, where the number of exposed hours is poorly defined. The applicable equation is Fatality rate = (Number of fatalities per year)/(Total number of people in applicable population)
Both the OSHA incidence rate and the FAR depend on the number of exposed hours. An employee working a ten-hour shift is at greater total risk than one working an eight-hour shift. A FAR can be converted to a fatality rate (or vice versa) if the number of exposed hours is known. The OSHA incidence rate cannot be readily converted to a FAR or fatality rate because it contains both injury and fatality information.
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OSHA incident rate (cases involving days away from work and deaths) Industry Chemicals and allied products Motor vehicles Steel Paper Coal mining Food Construction Agricultural Meat products Trucking All manufacturing
1985 0.49 1.08 1.54 2.06 2.22 3.28 3.88 4.53 5.27 7.28
FAR (deaths)
1998 0.35 6.07 1.28 0.81 0.26 1.35 0.6 0.89 0.96 2.1 1.68
1986 4 1 1.83
1990 1.2 0.6
40
7.2
67 10
5 3.7
1.2
Table 3.1 Accident Statistics for Selected Industries
Activity
Voluntary activity Staying at home Traveling by Car Bicycle Air Motorcycle Canoeing Rock climbing Smoking (20 cigarettes/day) Involuntary activity Struck by meteorite Struck by lightning (U.K.) Fire (U.K.) Run over by vehicle
FAR (deaths/108 hours)
Fatality rate (deaths per person per year)
3
17 x 10
57 96 240 660 1000 4000
4 105 500 105 6 1011 1 107 150 107 600 107
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Table 3.2. Fatality Statistics for Common Nonindustrial Activities
Recognizing that the chemical industry is safe, why is there so much concern about chemical plant safety? The concern has to do with the industry‘s potential for many deaths, as, for example, in the Bhopal, India, tragedy. Accident statistics do not include information on the total number of deaths from a single incident. Accident statistics can be somewhat misleading in this respect. For example, consider two separate chemical plants. Both plants have a probability of explosion and complete devastation once every 1000 years. The first plant employs a single operator. When the plant explodes, the operator is the sole fatality. The second plant employs 10 operators. When this plant explodes all 10 operators succumb. In both cases the FAR and OSHA incidence rate are the same; the second accident kills more people, but there are a correspondingly larger number of exposed hours. In both cases the risk taken by an individual operator is the same. It is human nature to perceive the accident with the greater loss of life as the greater tragedy. The potential for large loss of life gives the perception that the chemical industry is unsafe.
Chapter 4 Process safety Process safety focuses on preventing fires, explosions and accidental chemical releases in chemical process facilities or other facilities dealing with hazardous materials such as refineries, oil and gas production installations. QRA (Quantified Risk Assessment) for example focus on Process Safety. QRA is an approach for estimating the risk of chemical operations using the probabilistic information. And it is a fundamentally different approach from those used in many other engineering activities because interpreting the results of a QRA requires an increased sensitivity to uncertainties that arise primarily from the probabilistic character of the data. Estimating the frequencies and consequences of rare accidents is a synthesis process that provides a basis for understanding risk. (Throughout the published literature, the terms risk assessment and risk analysis are used interchangeably in reference to this process.) Using this synthesis process, you can develop risk estimates for hypothetical accidents based upon your experience with the individual basic events that combine to cause the accident. (Basic events typically include process component failures, human errors, and changes in the process environment, and more information is usually known about these basic events than is known about accidents.) System logic models are used to couple the basic events together, thus defining the ways the accident can occur.
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With the advent of this new safety analysis technology and the need for providing better input to risk management and safety improvement decisions, many CPI safety professionals are calling for increased use of QRA. And, given the contemporary technical and social environment, it is imperative that management personnel understand the strengths and weaknesses of QRA technology.
4.1 The process of risk analysis Risk analysis is the process of gathering data and synthesizing information to develop an understanding of the risk of a particular enterprise. Risk analysis usually involves several of the five risk management activities shown in Figure 4.1. CPI companies have many possible applications for risk analysis. For example, before proceeding with full-scale development of a new product, management may wish to determine whether the marketing of that product will succeed. In another instance, company executives may want to know how to allocate resources to minimize the chance of a catastrophic accident at a chemical process facility. This guide is concerned with the latter situation—assessing the risk of episodic events. With the understanding available from such risk analyses, you will be better equipped to evaluate and select risk management options.
Fig. 4.1.(a) Elements of risk management.
The effort needed to develop this understanding will vary depending upon the foundation of information you have for understanding the significance of potential accidents. If you have a great deal of pertinent, closely related experience with the activity you wish to know the risk of, then very little formal analysis may be needed. However, even minor changes can radically increase the risk of an accident. History is replete with examples of design ―improvements‖ or minor extrapolations that pushed a proven design beyond safe 19
limits. If, on the other hand, there is no relevant experience base for extrapolation, you will have to rely on analytical techniques or on your own intuition for answering risk analysis questions. However, no risk analysis technique can provide meaningful results if you do not have fundamental knowledge of process hazards.
Fig. 4.1.(b) Elements of risk analysis.
If your risk understanding is inadequate, we can use the process of risk analysis to acquire the understanding you need. The extent of risk analysis and the degree of risk understanding that are needed may vary. Sometimes, simply knowing what could go wrong (hazard identification) may be sufficient for your decision, and no elaborate quantification of likelihoods or effects would be needed. Occasionally, we may have sufficient understanding about what can go wrong and what the effects of an accident could be; however, you may still need information on how likely the accident is. In other cases the quantification of potential impacts alone will be adequate, and analysis of the likelihoods is unnecessary. In practice, few decisions require explicit quantification of both frequency and consequence.
4.2 Definition of QRA QRA is the art and science of developing and understanding numerical estimates of the risk (i.e., combinations of the expected frequency and consequences of potential accidents) associated with a facility or operation. It uses a set of highly sophisticated, but approximate, tools for acquiring risk understanding. QRA methods can be used throughout all phases of the life of a process (laboratory development, detailed design, operation, demolition, etc.). However, QRA is most effective when used to analyze a process whose design characteristics have been specified (i.e., the piping and instrument diagrams [P&IDs] are available, chemical reactions and other unit operations are known, and the process control strategy is defined) and for which there exists some relevant operating experience from similar systems. QRA can be used to investigate many types of risks associated with chemical process facilities, such as the risk of economic losses or the risk of environmental impact. But, in health and safety applications, the use of QRA can be classified into two categories: 1. Estimating the long-term risk to workers or the public from chronic exposure to potentially harmful substances or activities 20
2. Estimating the risk to workers or the public from episodic events involving a onetime exposure to potentially harmful substances or activities
Fig.4.2. The process of risk analysis.
In this guide, we will focus on the use of QRA in the safety assessment of acute hazards and episodic events only.
4.3 MISCONCEPTIONS ABOUT QRA Table 1 shows prevalent examples of misconceptions about QRA. Many are actually generalizations that are too broadly applied. Two of the most common misconceptions concern (1) the lack of adequate equipment failure data and (2) the cost of performing QRA. The core function of QRA is to provide information for decision making. QRA results in and of themselves cannot prove anything. However, decision makers can compare QRA risk estimates to their own risk tolerance criteria to decide whether a plant or operation is safe enough. The same QRA results can support both the plant manager‘s contention that the plant is safe, as well as the community activist‘s claim that the plant is unsafe. The difference lies in the individual‘s risk tolerance, not the QRA. TABLE 4.3.1. Misconceptions about QRA Technology and Risk • A QRA can prove that the plant is safe or unsafe. • QRA is a totally objective way to understand risk. • If we could measure risk accurately, our decisions would be easy. • If we do a QRA, we can reduce our risk to zero. • We analyzed all possible accidents. • We can usually predict risk to an accuracy of a factor of 2 or better. • We don‘t have enough data to do QRA. • We have enough data so we don‘t need to do QRA. • QRA is pure science. 21
Unfortunately, even if everyone agrees on a tolerable risk value, there are many other subjective factors that influence our understanding (and tolerance) of risk. If 1 fatality per year were tolerable from causes such as falls, electrocutions, or asphyxiations, would 100 fatalities be equally tolerable from catastrophic explosions predicted to occur, on average, once every 100 years? In both cases, QRA results would predict an average risk of one fatality per year. Are worker injuries more tolerable than public injuries? Are injuries to adults more tolerable than injuries to children? Typical QRA results simply report risk as injuries per year. Yet, there are many other subjective factors that influence a decision maker beyond the ―objective‖ numeric results of a QRA. No matter how accurate the QRA results are, the conscious decision to accept risk (actually, the decision is whether to spend more money to further reduce the risk) is always difficult when near the risk tolerance threshold. If the risk is clearly above tolerable thresholds (e.g., the risk of fire in a flammable storage area if uncontrolled welding operations are performed), then the decision to spend money to reduce that risk (e.g., to install a fire suppression system, to train a fire brigade, or to implement a hot work permit system) is relatively easy. Similarly, if the risk is clearly small (e.g., the risk of a meteorite puncturing a tank), then the decision to pend no money on meteorite shields is equally easy. However, should a high-high pressure alarm be installed in addition to the existing high pressure alarm and relief valve? The QRA results show that the change would reduce risk, but the manager must decide whether the benefit is worth the cost. QRA results can guide decision makers in their quest for continuous improvement in risk reduction, but zero risk is an unattainable goal. Any activity involves some risk. Even if it were hypothetically possible to eliminate the risk of every accident scenario in a QRA, some risk would still remain because no QRA examines every possible accident scenario. At best a QRA identifies the dominant contributors to risk from the system as it existed at the time of the analysis. Once those are eliminated, other minor risk contributors (including many that were left out of the original QRA because they were ―negligible‖ contributors, as well as new risks introduced by changes to eliminate the original risks) remain as the new dominant risk contributors. The availability of resources to perform the analysis is the primary constraint on the completeness of QRAs. Managers must balance the value of QRA results in their decision making against the cost of obtaining these results. It has been shown repeatedly that, when properly scoped and executed, QRA is very cost-effective. In the past, QRA has been used with little regard for minimizing analysis cost versus benefit (e.g., in the nuclear power industry). But QRA can be cost-effective when appropriately preceded by qualitative evaluations and risk screening methods that reduce the size and complexity of the QRA study. The accuracy of QRA results is also dependent on the analysis resources. Obviously, more complete QRA models can produce more accurate results. But even the best model is worthless if the input data are speculative or erroneous. Fortunately, the scarcity of processspecific data for some applications may not be an insurmountable problem.Also, the American Institute of Chemical Engineers (AICHE) has sponsored a project to expand and improve the quality of component failure data for chemical industry use. And many process facilities have considerable equipment operating experience in maintenance files, operating logs, and the minds of operators and maintenance personnel. These data can be collected and combined with industry wide data to help achieve reasonable QRA objectives. However, care must be exercised to select data most representative of your specific system from the wide range available from various sources. Even data from your own plant may have to be modified (sometimes by a factor of 10 or more) to reflect your plant‘s current operating environment and maintenance practices. 22
4.4 Criteria for electing to use QRA The decision whether to use QRA will be based on a number of factors, including the following: • Do I have a reasonable expectation that the QRA can satisfy my needs? • Is QRA the most efficient method? To answer these questions we must consider details associated with your particular needs and activities of interest. Figure 4.4 is an example of a decision tree we may find useful when considering QRA for particular process safety applications. The decision tree illustrates a flowchart of questions you can ask yourself (or others) to decide how far through the process of risk analysis to go to satisfy a need for increased risk understanding. Step 1 considers all of the background information discussed in Section 2.1. If the information requirement is based on a regulatory concern or a special purpose need, then Steps 2 through 5 are bypassed and a QRA should be performed. If the information is needed for decision making, you must determine whether the significance of the decision warrants the expense of a QRA. If not, you may be able to use less resource-intensive qualitative approaches to satisfy your information requirements. Table 8 contains examples of typical conclusions reached from qualitative risk analysis results. In Steps 2 through 5 of Figure 4.4 we will use subjective judgment to consider whether the situation involves major hazards, familiar processes, large consequence potential, or frequent accidents. The definition of major hazard (Step 2) may vary considerably from company to company, but managers should consider the inherent and intrinsic threat posed by the activity of interest (fire, explosion, toxic material release, etc.). A small hydrogen fire at a refinery pipe flange may be considered trivial, but that same fire in a semiconductor manufacturing clean room may be catastrophic. Even if the hazard potential is great, a company may have a large amount of relevant experience to base safety-related decisions upon, and QRA may not be required.
Examples of Possible Conclusions Using Qualitative Results • There is/is not a significant hazard associated with this plant. • There are few/many things that can go wrong and cause the accident of concern. • The effects of a hypothetical accident are likely/unlikely to be bad. • Implementing the following production capacity improvements will increase/decrease safety.
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FIGURE 4.4. Decision criteria for selecting QRA.
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FIGURE 4.4. Decision criteria for selecting QRA (cont.).
If sufficient experience does not exist, you should consider whether the consequence potential (Step 4) or the expected frequency of accidents (Step 5) is great. Consideration of consequence potential should include personnel exposure, public demographics, equipment density, and so forth in relation to the intrinsic hazard posed by the material of concern. In 25
Step 5 you may perceive that the expected frequency of accidents alone is important enough to justify a QRA. However, even though your company may not have much relevant experience with the activity of interest, if the consequence potential of these accidents is not great, you may conclude that the expected frequency of the potential accidents is low enough for you to make your decisions comfortably using qualitative information alone. Once a decision to use QRA has been made, you must decide whether frequency and/or consequence information is required (Steps 6 and 7). In some cases we may simply need frequency information to make your decision. For example, suppose you wish to evaluate the adequacy of operating procedures and safety systems associated with a chemical reactor. The main hazard of concern is that the reactor could experience a violent runaway exothermic reaction. You believe that you know enough about the severe consequences of a runaway and nothing more will be gained by quantifying the consequences of potential runaways. Instead, you decide to estimate the expected frequency of reactor upsets and safety system failures that could lead to reactor runaways. You use this estimate to identify weaknesses in the reactor operating procedures and protection system and to determine the most efficient ways to reduce the frequency, and therefore the risk, of reactor accidents. In other cases the opposite may be true—you may decide it is more fruitful for you to base your decision on the results of a consequence analysis alone. For example, suppose you wish to evaluate and select the best combination of design and release mitigation features for a proposed facility for storing a highly toxic and reactive material. You may believe that your design team has already established the best engineering approach for preventing accidents. But, you are still concerned about the safety/health effects of a release and what emergency response capabilities you should establish. You have your QRA analysts quantify the possible effects of a release, assuming a worst-case release occurs, to provide you with information on which to base your selection of emergency response capabilities. Whenever possible, relative comparisons of risk should be made (Step 8). Comparing relative risk estimates for alternative strategies avoids many of the problems associated with interpreting and defending absolute estimates. Table 9 contains examples of typical conclusions you can reach using relative risk estimates. In some cases, however, absolute estimates may be required to satisfy your needs. Table 10 contains a list of examples of typical conclusions possible using absolute risk estimates. Once the QRA results are available, we must evaluate the information and determine whether it fully satisfies your needs (Step 9). If so, the results should be put into an appropriate format for communication to other parties.
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TABLE 4.4. Classical Limitations of QRA Issue
Description
Completeness
There can never be a guarantee that all accident situations, causes, and effects have been considered.
Model Validity
Probabilistic failure models cannot be verified. Physical phenomena are observed in experiments and used in model correlations, but models are, at best, approximations of specific accident conditions.
Accuracy/Uncertainty
The lack of specific data on component failure characteristics, chemical and physical properties, and phenomena severely limit accuracy and can produce large uncertainties.
Reproducibility
Various aspects of QRA are highly subjective—the results are very sensitive to the analyst‘s assumptions. The same problem, using identical data and models, may generate widely varying answers when analyzed by different experts.
Inscrutability and use.
The inherent nature of QRA makes the results difficult to understand
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Chapter 5 Legislation and Law The Health and Safety Commission (HSC) conducted a review of health and safety regulation in 1994. 5.1. What health and safety law requires The basis of British health and safety law is the Health and Safety at Work etc. Act 1974.The Act sets out the general duties which employers have towards employees and members of the public ,and employees have to themselves and to each other. These duties are qualified in the Act by the principle of ‗so far as is reasonably practicable In other words, an employer does not have to take measures to avoid or reduce the risk if they are technically impossible or if the time, trouble or cost of the measures would be grossly disproportionate to the risk. What law requires here is what good management and common sense would lead employers to do anyway: that is, to look at what the risks are and take sensible measures to tackle them. The Management of Health and Safety at Work Regulations 1999 ( the Management Regulations ) generally make more explicit what employers are required to do to manage health and safety under the Health and Safety at Work Act. Like the Act, they apply to every work activity. The main requirement on employers is to carry out a risk assessment. Employers with five or more employees need to record the significant findings of the risk assessment. Risk assessment should be straightforward in a simple work place such as a typical office. It should only be complicated if it deals with serious hazards such as those on a nuclear power station, a chemical plant, laboratory or an oil rig. The HSE leaflet Five steps to risk assessment will give you more information. Besides carrying out a risk assessment, employers also need to: ❋make arrangements for implementing the health andsafety measures identified as necessary by the risk assessment; ❋appoint competent people ( often themselves or company colleagues) to to implement the arrangements;
help
them
❋set up emergency procedures; ❋provide clear information and training to employees; ❋ work together with other employers sharing the same workplace. 5.2. Action on health and safety: Options The Health and Safety Commission and its operating arm, the Executive (HSC/E), have spent over twenty years modernising the structure of health and safety law. Their aims to protect the health , safety and welfare of employees, and to safeguard others, principally the public, who may be exposed to risks from work activity. 28
HSC/E consult fully with people affected by their legislative proposals, and adopt various approaches based on assessing and controlling risk (What health and safety law requires). Among the things that can prompt action from HSC/E are: ❋changes in technologies, industries or risks; ❋ evidence of accidents and ill health, plus public concern; European Directives Where HSC/E consider action is necessary to supplement existing arrangements, their three main options are: ❋ guidance; ❋ Approved Codes of Practice; and ❋ regulations. HSC/E try to take whichever option, or options, allows employers most flexibility and costs them least, while providing proper safeguards for employees and the public. 5.2.1 Guidance HSE publishes guidance on a range of subjects (please see the end of this guide). Guidance be specific to the health and safety problems of an industry or of a particular process used in a number of industries. The main purposes of guidance are: ❋to interpret -- helping people to understand what the law says -- including for requirements based on EC Directives fit with those under the
example
❋Health and Safety at Work Act; ❋to help people comply with the law; ❋to give technical advice. Following guidance is not compulsory and employers are free to take other action. But if they do follow guidance they will normally be doing enough to comply with the law. (Please also see the sections below on Approved Codes of Practice and regulations, which explain other ways in which employers are helped to know whether they are doing what the law requires.) HSC/E aim to keep guidance up-to-date, because as technology change, risks and the measur needed to address them change too. 5.2.2 Approved Codes of Practice Approved Codes ofPractice offer practical examples of good practice. They give advice on to comply with the law by, for example, providing a guide to what is ‗reasonably practicable‘. For example, if regulations use words like ‗suitable and sufficient‘, an Approved code of 29
Practice can illustrate what this requires in particular circumstances . Approved Codes of Practice have a special legal status. If employers are prosecuted for a breach of health and safety law, and it is proved that they have not followed the relevant provisions of the Approved Code of Practice , a court can find them at fault unless they can show that they have complied with the law in some other way . HSC consulted in 1995 on the role of Approved Codes of Practice in the health and safety system and concluded that they could still be used in support of legal duties in specific circumstances. 5.2.3 Regulations Regulations are law, approved by Parliament. These are usually made under the Health and Safety at Work Act, following proposals from HSC. This applies to regulations based on EC Directives as well as ‗homegrown‘ ones . The Health and Safety at Work Act, and general duties in the Management Regulations , are goal-setting (see ‗What form do they take? ‘) and leave employers freedom to decide how to control risks which they identify. Guidance and Approved Codes of Practice give advice . But some risks are so great, or the proper controlmeasures so costly, that it would not be appropriate to leave employers is creation in deciding what to do about them . Regulations identify these risks and set out specific action that must be taken. Often these requirements are absolute to do something without qualification by whether it is reasonably practicable.
5.3 How regulations apply Some regulations apply across all companies , such as the Manual Handling Regulations which apply wherever things are moved hand or bodily force , and the Display Screen Equipment Regulations which apply wherever VDUs are used. Other regulations apply to hazards unique to specific industries, such as mining or nuclear. What form do they take? HSC will where appropriate propose regulations in goal-setting form: that is, settingout what must be achieved, but not how it must be done. Sometimes it is necessary to be prescriptive, that is spelling out in detail what should be done . Some standards are absolute . For example , all mines should havetwo exits; contacts with live electrical conductors should be avoided . Sometimes European law requires prescription. Some activities or substances are so inherently hazardous that they require licensing, for example explosive and asbestos removal Certain big and complex installations or operations require ‗safety cases‘, which are large scale risk assessments subject to scrutiny by the regulator. For example, railway companies are required to produce safety cases for their operations . The relationship between the regulator and industry . As mentioned above ,HSC consults widely with those affected by its proposals. HSC/E work through: ❋ HSC‘ s Industry and Subject Advisory Committees , which have members drawn from the areas of work they cover, and focus on health and safety issues in particular industries (such as the textile industry, construction and education or areas such as toxic substances and genetic modification); intermediaries, such as small firms organisations.
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❋providing information and advice to employers and others with responsibilities Health and Safety at Work Act;
under the
❋guidance to enforcers, both HSE inspectors and those of local authorities; ❋the day-to-day contact which inspectors have with people at work. HSC directly canvasses the views of small businesses . It also seeks views in detail from representatives of small businesses about the impact on them of proposed legislation.
5.4 What next? The Review of Regulation concluded that the present system of health and safety regulation generally works well, though it identified several areas where improvements can be made. Although the Review has ended , our work in support of Better Regulation continues. The Review programme has formed an important basis for long-lasting successes in improving workplace health and safety. Policies and initiatives flowing from it continue to support our priority aims and objectives , and will be refined in the coming years, adapting and evolving to take account of changes in technology, workplace trends and the needs of those involved.
5.5 Some important pieces of health and safety Besides the Health and Safety at Work Act itself, the following apply across the full range of workplaces: 1 Management of Health and Safety at Work Regulations 1999: require employers to carry out risk assessments , make arrangements to implement necessary measures, appoint competent people and arrange for appropriate information and training. 2 Workplace ( Health , Safety and Welfare) Regulations 1992: cover a wide range of basic health , safety and welfare issues such as ventilation, heating, lighting, workstations, seating and welfare facilities. 3 Health and Safety(Display Screen Equipment) Regulations 1992: set out requirement for work with Visual Display Units (VDUs). 4 Personal Protective Equipment at Work Regulations 1992 : require employers to provide appropriate protective clothing and equipment for their employees. 5 Provision and Use of Work Equipment Regulations 1998 : require that equipment provided for use at work, including machinery, is safe. 6 Manual Handling Operations Regulations 1992: cover the moving of objects by hand or bodily force. 7
Health and Safety (First Aid) Regulations 1981: cover requirements for first aid.
8 The Health and Safety Information for Employees Regulations 1989: require employ ers to display a poster telling employees what they need to know about Health and safety. 31
9 Employers‘ Liability (Compulsory Insurance) Act 1969: require employers to take out insurance against accidents and ill health to their employees. 10 Reporting of Injuries , Diseases and Dangerous Occurrences Regulations 1995 (RIDDOR ) : require employers to notify certain occupational injuries , diseases and dangerous events. 11 Noise at Work Regulations 1989 : require employers to take action to protect employees from hearing damage. 12 Electricity at Work Regulations 1989: require people in control of electrical systems to ensure they are safe to use and maintained in a safe condition. 13 Control of Substances Hazardous to Health Regulations 2002 (COSHH): require employers to assess the risks from hazardous substances and take appropriate precautions. In addition, specific regulations cover particular areas, for example asbestos and lead, and: 14 Chemicals (Hazard Information and Packaging for Supply) Regulations 2002: require suppliers to classify, label and package dangerous chemicals and provide safety data sheets for them. 15 Construction ( Design and Management ) Regulations 1994 : cover safe systems of work on construction sites. 16 Gas Safety ( Installation and Use ) Regulations 1994 : cover safe installation, maintenance and use of gas systems and appliances in domestic and commercial premises. 17 Control of Major Accident Hazards Regulations 1999: require those who manufactur store or transport dangerous chemicals or explosives in certain quantities to notify the relevant authority. 18 Dangerous Substances and Explosive Atmospheres Regulations 2002 : require employers and the selfemployed to carry out a risk assessment of work activities involving dangerous substances.
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Chapter 6 Recent Developments 6.1 25 Years after the Bhopal Gas Disaster The bhopal gas disaster on the night of December 2nd/3rd, 1984 led to a number of changes in legislation regarding the management of chemical process safety. The recent massive blaze at the petroleum storage facility at Jaipur indicates the need for improvement in managing chemical process safety in India. A comparison of the changes in legislation made in the USA after the Bhopal Gas Disaster with the changes made in India is given below:
6.1.1 Changes made in USA: 1.After the Bhopal Gas Disaster and other accidents in the 1980‘s amendments were made to the Clean Air Act (1991). OSHA (Occupational Safety and Health Administration) was authorized to develop its 29 CFR 1910.119 rule of 1992, Process Safety Management. This system is mandatory in the USA since 1992 for chemical industries, storing or processing highly hazardous chemicals, above a threshold quantity. After the implementation of this rule, there was a major incident at the BP Texas refinery in 2005. A thorough investigation about the reasons for the incident and follow up actions are clearly visible to the public. The investigation reports of the incident are made available to the public on the web. 2.The US Environmental Protection Agency also implemented the Risk Management Program in 1996 to prevent an off –site disaster (An off-site disaster is an event that has repercussions outside the boundary walls of the chemical industry in which the incident took place). 3.The US Chemical Safety Board was set up in January 1998 by an amendment of the Clean Air act. It is authorized to investigate chemical accidents in the USA and publish its investigation reports on its website www.csb.gov. The board cannot impose fines or promulgate regulations. It creates public awareness by publishing its investigation reports on Web.
6.1.2. Changes Made in India: 1.After the Bhopal gas disaster, the Factories Act was amended to assign the responsibility of the ―occupier‖, who is legally responsible for the safety of the workplace and workers, to the highest level of management in an organization. For a public limited company, one of the directors on the board had to be designated as ―occupier‖. The Environmental legislation also underwent changes, with the Environment Protection Act introduced in 1986. Under this act, a number of new legislations were framed. The Manufacture, Storage and Import of Hazardous Chemical rules, 1989 required safety audits to be carried out in hazardous chemical factories, storing more than a threshold limit of hazardous chemicals. 2.The Chemical Accidents (Emergency Planning, Preparedness and Response) Rules, 1996 was also introduced. Preparation of on-site Emergency Plan by the Industry and Off-site Plan by the District Collector and the constitution of four-tier Crisis Groups at the Centre, State, District and Local level for management of chemical accidents are mandatory under these Rules.
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6.2 Recommendations to improve chemical process safety management in India: 1.The enforcement of existing legislation regarding chemical process safety by the Indian authorities must be made effective by training the law enforcers in the latest developments in prevention of chemical accidents, inspection and management system audit techniques. 2.While statutory safety audits continue to be performed in the chemical industries, public should also be informed about the status of implementation of the recommendations of safety audit. 3.The investigation of Chemical Process Incidents in India should be carried out by an independent body simlar to the Chemical Safety Board of USA and their investigation reports must be made public. 4. There is a requirement in Factories rules Section 41 C for hazardous operations that "the occupier must appoint persons who possess qualifications and experience in handling hazardous substances and are competent to supervise such handling within factory.
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Chapter 7 References Frank P. Less – Loss Prevention in the Process Industries (Volume 1), Butterworth-Heinemann. Frank P. Less – Loss Prevention in the Process Industries (Volume 2), Butterworth-Heinemann. Frank P. Less – Loss Prevention in the Process Industries (Volume 3), Butterworth-Heinemann. J. S. Arendt, D. K. Lorenzo - Evaluating process safety in chemical industry, A CCPS concept book. Wikipedia.org
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