GP 44-10 Plant Layout

Document No.

GP 44-10

Applicability

Group

Date

7 September 2005

Guidance on Practice for Plant Layout

GP 44-10

BP GROUP ENGINEERING TECHNICAL PRACTICES

7 September 2005

GP 44-10 Guidance on Practice for Plant Layout

Foreword This is the first issue of Engineering Technical Practice (ETP) BP GP 44-10. Guidance on Practice (GP) is based on parts of heritage documents from the merged BP companies as follows:

British Petroleum RP 44-7

Plant Layout (February 1996).

Amoco A BD-ELO-00-E A BD-ELO-00-G

Basic Design—Equipment Layout and Spacing—Design Specification (October 1997). Basic Design—Equipment Layout and Spacing—Guide (October 1997).

ARCO Oil and Gas Design Guideline 5.5

Safety Design and Analysis – Equipment Spacing (May 1992).

Copyright  2005, BP Group. All rights reserved. The information contained in this document is subject to the terms and conditions of the agreement or contract under which the document was supplied to the recipient’s organization. None of the information contained in this document shall be disclosed outside the recipient’s own organization without the prior written permission of Director of Engineering, BP Group, unless the terms of such agreement or contract expressly allow.

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Table of Contents Page 1.

Scope...................................................................................................................................... 5

2.

Normative references.............................................................................................................. 5

3.

Terms and definitions.............................................................................................................. 6

4.

Symbols and abbreviations.....................................................................................................8

5.

General................................................................................................................................... 9 5.1. Application of this GP...................................................................................................9 5.2. Requirements............................................................................................................... 9 5.3. Philosophy..................................................................................................................10 5.4. Maintenance access...................................................................................................10 5.5. Future equipment.......................................................................................................11

6.

Onsite plant/unit layout.......................................................................................................... 11 6.1. Philosophy.................................................................................................................. 11 6.2. Site infrastructure.......................................................................................................12 6.3. Buildings..................................................................................................................... 15

7.

Plot layout............................................................................................................................. 16 7.1. General...................................................................................................................... 16 7.2. Plant sections.............................................................................................................16 7.3. Separation distances..................................................................................................17 7.4. Process units enclosed within buildings.....................................................................17 7.5. Plot drainage..............................................................................................................17 7.6. Special fire risk areas.................................................................................................18 7.7. Plant scale model.......................................................................................................18 7.8. Construction considerations.......................................................................................18

8.

Accessways and in plant roads.............................................................................................19 8.1. Philosophy..................................................................................................................19 8.2. Recommended widths and clearances.......................................................................19 8.3. Routing....................................................................................................................... 20 8.4. Access to platforms....................................................................................................20

9.

Piping.................................................................................................................................... 20 9.1. References................................................................................................................. 20 9.2. Routing....................................................................................................................... 20 9.3. Minimum clearances..................................................................................................21 9.4. Piping supports and pipe tracks.................................................................................21 9.5. Pipe racks.................................................................................................................. 21 9.6. Valve operation...........................................................................................................22 9.7. Spades (blinds).......................................................................................................... 22 9.8. Sample points............................................................................................................22

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9.9.


Battery limit isolation..................................................................................................22

10.

Equipment............................................................................................................................. 22 10.1. Philosophy..................................................................................................................22 10.2. Rotating equipment....................................................................................................22 10.3. Fired heaters and high-temperature lines...................................................................23 10.4. Air-cooled heat exchangers........................................................................................24 10.5. Shell and tube heat exchangers.................................................................................24 10.6. Air intakes and discharges.........................................................................................25 10.7. Pressure relief devices...............................................................................................26

11.

Above-ground bulk storage and transfer areas.....................................................................26 11.1. General...................................................................................................................... 26 11.2. Class I, II, III and unclassified liquids..........................................................................28 11.3. Pressurised LPG storage...........................................................................................29 11.4. LNG storage............................................................................................................... 30

Annex A (Normative) Guidance on clearances...............................................................................31 A.1. General...................................................................................................................... 31 A.2. Vertical....................................................................................................................... 31 A.3. Horizontal...................................................................................................................31

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1.


Scope This GP provides guidance on all aspects of the layout of process plant, associated offsite facilities, and their equipment and structures within onshore installations. This GP is specifically applicable to conventional ‘outdoor’ installations for processing, storing, and handling flammable or toxic fluids. Examples include gas processing plants, refineries, chemical plants, marine loading/unloading facilities, and field sites; offshore facilities are excluded. This GP should be used for units constructed on site or modules fabricated offsite. This document is not retroactive, but as far as practicable, should be applied to expansions and modifications on existing sites as well as the installation of temporary facilities.

2.

Normative references The following normative documents contain requirements that, through reference in this text, constitute requirements of this technical practice. For dated references, subsequent amendments to, or revisions of, any of these publications do not apply. However, parties to agreements based on this technical practice are encouraged to investigate the possibility of applying the most recent editions of the normative documents indicated below. For undated references, the latest edition of the normative document referred to applies.

BP GP 04-10 GP 04-20 GP 04-30 GP 12-01 GP 14-01 GIS 14-011 GP 22-10 GP 22-20 GIS 22-201 GP 24-10 GP 24-03 GIS 24-233 GP 26-10 GP 30-55 GP 30-85 GP 34-00 GP 42-10 GP 44-30 GP 44-60 GP 44-65 GP 44-70 GP 44-80 GP 76-01

Guidance on Practice for Drainage Systems. Guidance on Practice for Civil Engineering. Guidance on Practice for Design of Buildings Subject to Blast Loading. Guidance on Practice for Power System Design. Guidance on Practice for Noise Control. Guidance on Industry Standard for Noise Control. Guidance on Practice for Design of Fired Heaters to ISO 13705 (API 560). Guidance on Practice for Design of Flares (API 537). Guidance on Industry Standard for Flares (API 537). Guidance on Practice for Fire Protection – Onshore. Guidance on Practice for Inherently Safer Design Concept Selection. Guidance on Industry Standard for Fire Water Pumps and System Design. Guidance on Practice for Heat Exchangers. Guidance on Practice for Control Rooms. Guidance on Practice for Fire and Gas Detection. Guidance on Practice for Machinery. Guidance on Practice for Design of Process Piping (ASME B31.3). Guidance on Practice for Event Modelling and Risk Based Evaluation. Guidance on Practice for API RP 500 Area Classification. Guidance on Practice for IP 15 Area Classification. Guidance on Practice for Overpressure Protection. Guidance on Practice for Relief Disposal Systems. Guidance on Practice for HSSE in Design and Loss Prevention.

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American Institute of Chemical Engineers (AIChE) Center for Chemical Process Safety (CCPS), Guidelines for Facility Siting and Layout.

American Petroleum Institute (API) API RP 521 API RP 752 API RP 2001 API Pub 2218 API Std 2510 API Std 2610

Guide for Pressure-Relieving and Depressuring Systems. Management of Hazards Associated with Location of Process Plant Buildings. Fire Protection in Refineries. Fireproofing Practices in Petroleum and Petrochemical Processing Plants. Design and Construction of LPG Installations. Design, Construction, Operation, Maintenance, and Inspection of Terminal & Tank Facilities.

British Standards Institute (BSI) BS 4485

Water Cooling Towers.

European Standard (EN) EN 1473

Installation and Equipment for Liquefied Natural Gas - Design of Onshore Installations.

Energy Institute (EI) – Formerly the Institute of Petroleum (IP) IP 19

IP Model Code of Safe Practice – Part 19: Fire Precautions at Petroleum Refineries & Bulk Storage Installations.

National Fire Protection Association (NFPA) NFPA 30 NFPA 58 NFPA 59A NFPA 497

Flammable and Combustible Liquids Code. Liquefied Petroleum Gas Code. Standard for the Production, Storage, and Handling of Liquefied Natural Gas (LNG). Recommended Practice on the Classification of Flammable Liquids, Gases, or Vapors and of Hazardous (Classified) Locations for Electrical Installations in Chemical Process Areas.

Process Industry Practices (PIP) PNC00003

3.

Process Unit and Offsites Layout Guide.

Terms and definitions For the purposes of this GP, the following terms and definitions apply: Accessways Paved areas for either vehicular or pedestrian access within plot limits. Administration Area That part of the site containing the main office buildings. Battery Limit The boundary of a process unit enclosing all equipment and unit limit block valves.

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Complex A group of units, the operation of which is interlinked, e.g. a group consisting of vacuum unit, catalytic cracker, alkylation unit, and sulphur recovery unit. On a small site, the term ‘complex’ may refer to all the process units on the site. Depot A storage area of capacity less than 5 000 tonnes (5 512 tons), with no processing facilities but with import and export facilities. Equipment The individual items, e.g. heat exchangers, that may make up a section. Flammable Vapour A general term to describe a flammable vapour or gas. Ignition/Open Flame Area An area containing equipment with open flame and, as practicable, surfaces hot enough to ignite flammable material in the process area. In Plant Roads Roads serving one or more units or sections (of units) within a plot. Major Site Road The main network of thoroughfare serving all plots within a site. Minor Site Road Other site roads serving one or more plots within the site. Module Any assembly of equipment items and their associated piping, instrumentation, electrical equipment, structure, and fittings, combined into a transportable subsection of a process unit or offsite facility. The definition includes all sizes and sources of assembly, including contractor or vendor pre-assembled units, preassembled or dressed complex equipment items, e.g. towers or fired heaters and pipe rack units. Occupied Building A building is considered to be occupied if any of the following criteria are met: •

A person(s) is (are) assigned to a location as a workstation or command and control center in case of an emergency.

•

A person(s) is (are) assigned to a location designated as a safe haven in case of an emergency.

•

A building is staffed 8 work-hours in a 24 hour period as part of an individual’s primary job function.

•

Cumulative occupancy is equal to or greater than 200 hours per week.

Offsites The units and equipment that are not specifically part of the processing units, but which provide a service to the processing units. Offsites includes utilities (except within a process unit) and tankage. Pipe Track A grouping of unburied piping at or slightly below ground level. Page 7 of 29

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Plant A general term to describe any one or all the units on a given site. Plot An area of the site where a unit e.g. refinery CDU, chemical plant, or storage terminal is located. Section Part of a unit, e.g. the fractionation part of a catalytic cracker. Service Areas Workshops, stores, fire station, laboratory, or similar buildings. Site The land owned by BP or for which BP is responsible (i.e. the land within the perimeter fence). Storage Terminal A storage area with no processing facilities, but with import and export facilities. If the storage capacity is less than 5 000 tonnes (5 512 tons), this is classified as a depot. Tank Compound An area containing one or more tanks. Unit A main production component or plant in a refinery or chemical complex, e.g. a catalytic cracker or acrylonitrile plant. Note that ‘unit’ is the usual term in refineries whereas ‘plant’ is the usual term in chemical factories. Utilities Steam and power generation and transmission; condensate, process water, and cooling water treatment and supply; instrument and service air supply; effluent treatment and similar services.

4.

Symbols and abbreviations For the purpose of this GP, the following symbols and abbreviations apply: BI

Business interruption

CSE

Concept Safety Evaluation

ISBL

Inside battery limit(s)

LNG

Liquefied natural gas.

LPG

Liquefied petroleum gas(es)

NGL

Natural gas liquid(s)

NPSH

Net positive suction head

OSBL

Outside battery limit(s)

PD

Property Damage

PSR

Project Security Review Page 8 of 29

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5.


QRA

Quantified risk assessment

SI

Systeme International d’Unites

General

5.1.

Application of this GP

5.1.1.

General

Layout is concerned with the spatial arrangement of the buildings and process equipment (and its interconnections) within the plant boundaries, the location of the plant area within the site boundaries, and the location of the site relative to the surrounding environment and residential communities. This GP makes a clear distinction between the layout of the various plants/units on a site and the arrangement of process vessels or equipment etc. within the plant (or plot). 5.1.2.

Application to existing facilities

This document is not retroactive, but as far as practicable, should be applied to expansions and modifications on existing sites as well as the installation of temporary facilities. 5.1.3.

5.2.

Legislative regulations, local codes, and standards

a.

If there are local legislative regulations on layout for the country in which the site is located, these must be complied with other than where this GP is more rigorous than such statutory requirements.

b.

Minimum distance of equipment from site property lines shall comply with national (e.g. federal), state, and local codes and safety regulations or deed restrictions. If there is a conflict, the greater distance shall govern.

c.

If local codes and standards for plant layout conflict with guidance given in this GP, the more stringent text shall govern upon approval by BP.

Requirements a.

b.

5.3.

Projects shall undergo a risk assessment to an appropriate level of detail as defined in GP 44-30. 1.

Calculations relevant to layout or concerning potential major releases of hazardous materials shall be made available for such a review.

2.

Less stringent exceptions to or variances from requirements specified in this GP shall be supported and documented by a risk assessment.

New sites shall undergo a Project Security Review (PSR). 1.

A PSR should be considered for expansions, revamps, and temporary facilities.

2.

A regional security adviser can be located at: http://gbcweb.bpweb.bp.com/bpsecurity/Contacts/FindYourRSA.asp

c.

Projects shall undergo a Concept Safety Evaluation (CSE) as described in GP 24-03. GP 24 03 shall be referenced for inherently safer design guidance.

d.

Environmental considerations shall be included in the plant layout design to ensure that projects and developments strive to achieve the corporate goal of “no damage” to the environment. Projects shall be in compliance with HSSE in design and loss prevention in accordance with the GP 76-01.

e.

Plant layout shall comply with noise control in accordance with GP 14-01 and GIS 14-011.

Philosophy Page 9 of 29

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Plant layout shall identify and adopt the safest cost effective layout that meets the requirements of the process design, safe operation/maintenance, and emergency action. a.

b.

c.

d.

5.4.

5.5.

6. 6.1.

Minimum spacing within plant shall be in accordance with: 1.

Clause 11 for aboveground storage tanks.

2.

NFPA 58 and API Std 2510 (or equivalent European standard) for LPG.

3.

EN 1473 or NFPA 59A for LNG.

4.

API 2001 for fire protection in refineries.

Separation distances shall satisfy the following: 1.

Provide minimum access clearance for emergency response actions.

2.

Allow safe access for operation and emergency evacuation.

3.

Provide minimum access clearance for maintenance.

4.

Give an economic design.

PIP PNC00003 offers separation distances for common items of equipment that satisfy the aforementioned criteria. 1.

These distances should be regarded as a maximum for economic layout purposes.

2.

Separation distance adjustments either way may be justifiable if a change could materially affect the hazard or risk or if unusual access or process reasons exist.

3.

Any proposal to increase these separation distances should be subject to a cost benefit analysis.

Separation distances are flexible and should be judged on a hazard and risk based approach. Whilst a quantified risk based approach may be used for location of units, buildings etc. within a site, such an approach is, in general, considered impracticable as a basis for equipment layout within a unit.

Maintenance access a.

Equipment shall be located with adequate access for mobile handling equipment during maintenance.

b.

If elevated equipment requires crane handling, sufficient area to manipulate a boom, a manual operated travelling crane, or a monorail and trolley shall be provided.

c.

Equipment layout shall avoid the need to lift heavy pieces of frequently maintained equipment during unit operation over in-service process lines or equipment or provide passive protection (such as concrete containment).

Future equipment a.

Space for probable future equipment shall be designated and located adjacent to related equipment. The allocation of such space should be addressed during the initial project risk assessment in order to identify potential hazards associated with probable future equipment.

b.

Sewers and other underground piping and electrical runs shall be routed clear of known future equipment foundations.

Onsite plant/unit layout Philosophy a.

The site area shall be divided into plots, and if possible the plots should be rectangular.

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b.

The area of a plot shall be no greater than 20 000 m2 (215 278 ft2) and no side should be greater than 200 m (656 ft).

c.

A single plot may contain more than one process unit or section.

d.

Irrespective of whether process units are on the same or adjacent plots, spacing requirements outlined in this GP shall be satisfied. Spacing between process units shall take into account the following factors:

e.

1.

Exposure to possible fire radiation.

2.

Exposure to possible explosion overpressure.

3.

Maintenance requirements, including unrestricted hot work, of one unit while adjacent units are in service.

4.

Business interruption potential and relative value of the units involved.

5.

Prevailing wind direction.

6.

Access by emergency response equipment.

7.

Future expansion.

Plant separation should consider the following: 1.

Maximum size of flammable gas cloud from one plant area does not significantly intrude into adjacent areas.

2.

The magnitude of a gas explosion is not significantly increased by proximity of adjacent plant units.

3.

Damage caused in one area does not lead to escalation in adjacent areas.

f.

If there is flow between individual units, the layout of the units should be, as far as economical, in a logical order of flow.

g.

Process units with hazardous inventories shall be located to minimise the risk of any inadvertent release of fluid to personnel within the site, and also on activities outside the site boundary. Topography, prevailing winds, personnel safety, and nearby population centres shall be considered in selecting the most suitable location.

h.

Flammable material storage should be located on separate plots from process units. Flammable material may only be stored on a process unit plot provided all other options for separate plot location have been ruled out, additional risk reduction measures are incorporated, and a comprehensive risk assessment has been conducted.

i.

Field fabricated towers, fired heaters, etc. should be located at unit limits for construction convenience, if practicable. Exceptions may be taken in consideration of process design or hazard management benefits.

j.

Plant layout studies/ reviews should establish credible fire scenarios and the extent of direct flame impingement/ thermal radiation produced by the fire. 1.

This should be taken into account when finalising layouts.

2.

Spacing between tanks and other items of plant can be relaxed with a higher degree of fire protection.

3.

In all cases, criticality of plant and equipment and implications of loss for asset damage, business interruption and reputation should be considered, as well as those for life safety.

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6.2.

Site infrastructure

6.2.1.

Roads

6.2.2.

6.2.3.

6.2.4.

6.2.5.

a.

Site roads shall separate plots. Refer to GP 04-20 for minimum width for site roads.

b.

Equipment shall be located so that site roads are not classified as a hazardous area as defined in GP 44-60 or GP 44-65. 1.

Minor site roads shall not be in an area classified as Zone 0 or 1 (Class I Division 1).

2.

Any minor site road or in-plant road classified as Zone 2 (Class I Division 2) shall have controlled access.

Utilities

a.

Site utility services shall be grouped together in a non-hazardous area with exceptions being utility services integral to process unit operation.

b.

Site utility services should be located so that essential utility supplies can be maintained under emergency conditions (i.e. in the event of a flammable vapour release). The separation distances should be determined on a risk-based approach such that essential utility supply functions can be maintained within an agreed reliability.

c.

Cables shall be routed in accordance with the requirements of GP 12-01.

Firewater pumps

a.

Firewater pumps shall be sufficiently remote from processing, storage, and loading areas to minimize the risk of fire or blast damage to the pumps given protective measures installed (e.g. fire/blast resisting enclosure).

b.

The pumping facilities shall be capable of operation during the reasonable worst-case fire scenario and during primary power supply outage.

c.

The primary and secondary firewater pumps shall be located in different areas to prevent common mode failure.

d.

Requirements for firewater supply and distribution are given in GP 24-10 and GIS 24-233.

Cooling towers

a.

The direction of the prevailing wind shall be considered in selecting the location of cooling towers. Cooling towers should be located with air intake sides generally parallel to direction of prevailing wind.

b.

The towers shall be located to optimise maintenance accessibility and minimise any nuisance, both within and outside the site, from water blowout, evaporation, drift, and ice formation.

c.

Cooling towers shall be placed clear of process areas susceptible to fire risk.

d.

The requirements of BS 4485 or equivalent national standard shall be met.

Offsite effluent treatment facilities

a.

Contaminated water drainage from onsite and offsite areas shall be routed to suitable treatment facilities as detailed in GP 04-10 or a particular project specification.

b.

The facilities should be located to maximise gravity flow.

c.

If flammable vapours are present, consider locating the effluent treatment facilities remote and downwind from sources of ignition, in the prevailing wind direction.

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6.2.6.

6.2.7.


Flares

a.

The location, spacing, orientation, and height of flares shall be determined, for the particular site, by a full assessment of the factors involved. The design considerations and general principles that determine the type and location of flares, and the routes for closed relief systems are covered in GP 22-20, 44-70, and 44-80 and GIS 22-201.

b.

The following principles on siting should be applied: 1.

The flare(s) should, ideally, be located as close as practicable to the process units served, so as to allow the shortest, most direct, route(s) for the closed relief header(s), whilst avoiding passage through special fire risk areas.

2.

They should also be as far as practicable from public occupied areas that are, or may be in the future, located adjacent to the site boundaries.

3.

Design of the flare location shall consider thermal radiation, noise, luminosity, potential odour, potential ground level emissions, and ignition source related to the flare.

4.

A side-wind location (relative to the prevailing wind direction) from process facilities and similar sources of major release of flammable vapour is preferred.

5.

If more than one flare is provided, the location of each shall be based on operational requirements. The locations of all flares should be determined by any need for independent operation or maintenance of individual flares. This may require suitable spacing of separate flare stacks, or a tower-mounted multi-flare stack system. The latter should have facilities for lowering the stacks separately, to ensure that maintenance on any one flare stack can be carried out while the remaining flare stack system remains in operation.

6.

Minimum spacing of 60 m (197 ft) from aboveground facilities for elevated flares and 150 m (492 ft) for unshielded ground flares or burn-pits are suggested to provide a preliminary estimate for a restricted access zone around the flare-tip/stack. The actual spacing shall be that resulting from design calculations as described in GP 44-80.

Blowdown stacks to atmosphere

Blowdown stack to atmosphere shall comply with GP 44-80. 6.2.8.

Bulk rail/road/marine loading and unloading racks

6.2.8.1.

Location

a.

If loading and unloading racks handle bulk flammable or hazardous raw materials or products, these facilities should, preferably, be consolidated in a single remote area on the periphery of the site but should be at a safe distance from any offsite population.

b.

This area should be clear of roads, railways, and concentrations of personnel, if any of these are not directly associated with the loading or unloading operations.

c.

The loading and unloading facilities should be downwind or crosswind from process units and sources of ignition based on the prevailing wind. If this is impracticable, the loading/unloading area may be placed upwind at a prudent distance deemed by a thorough hazard analysis.

d.

For large sites containing several independent plants or units, loading and unloading racks local to individual plants may be required.

e.

Access from the site boundary to and from the loading and unloading racks should, preferably, be separate from the main access to the site, and shall be located to minimise traffic through process areas.

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6.2.8.2.

6.2.8.3.


Layout

a.

Onshore loading/unloading and transfer areas shall be located on level ground.

b.

Loading/unloading areas for road transport shall have adequate space for access for filling, parking, and manoeuvring. A drive through rack arrangement is preferred.

c.

Loading/unloading areas for rail transport shall include adequate spur tracks for standing, filling, shunting, and may require a siding for unserviceable rolling stock.

d.

Loading/unloading areas for container transport (e.g. bags, drums, crates) shall have adequate space for lifting and manoeuvring. Space may also be required for temporary placement of multiple containers during transfer.

e.

Loading/unloading areas for marine transport shall include adequate space for accessing transfer lines, docking, and positioning.

f.

For loading and unloading areas with potentially high risk to life, there shall be at least two independent escape routes for emergency egress.

g.

For additional guidance on the layout of material transfer facilities, refer to API Std 2610.

Security

Sites shall be within a restricted access perimeter fence. Admission to sites shall be through a security checkpoint. Some buildings, e.g. amenity buildings, may need to be located outside the fence. 6.3.

Buildings

6.3.1.

Location

a.

A central control building (with or without satellite control buildings) for regulatory control and online optimisation may be used for all units in a process complex. Alternatively, dedicated control buildings may be required for individual process units or for parts of the site remote from the main processing area, e.g. a main tank farm or product loading facilities.

b.

Occupied buildings shall be provided with accessways and ideally should be located in an area classified as electrically safe. 1.

Occupied buildings shall not be located in any area classified as Zone 0 or Zone 1 (Class I Division 1).

2.

If it is unavoidable that an occupied building be located in an area classified as Zone 2 (Class I Division 2), it should conform to the requirements of GP 44-65 (GP 44-60).

c.

Control building shall be located away from noise sources and on prevailing upwind side of process and ignition/open flame areas, taking into consideration location of existing units.

d.

Control buildings shall be located to allow unobstructed emergency pedestrian escape off the plot. The escape route shall not cross any special fire risk area (see 7.6) and should not pass through an area containing process plant.

e.

Refer to GP 04-30 for occupied buildings including occupied portable buildings such as those used during construction, startup, commissioning, and turnarounds.

f.

For further location guidance for process plant buildings, refer to API 752 or equivalent industry standard(s).

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6.3.2.

6.3.3.


Blast resistance

a.

Control buildings and other occupied site buildings whether permanent or temporary shall be designed and located such that the risk to occupants is demonstrated to be acceptable.

b.

Further guidance is available in GP 04 30 and 30-55.

Toxic hazard considerations

If a unit could produce a major toxic release, the position of the building should be specified after taking into account the following:

7. 7.1.

a.

Pressurisation and ventilation of the building.

b.

Possible safe haven designation (i.e. possible shelter in place requirements) of the building.

c.


d.

Escape routes.

e.

Operator involvement in safe shut down of the plant.

f.

Other design factors.

Plot layout General The plot layout shall be an economical design to meet the process and licensors’ objective reflecting the need for safety to life and property, and allowing adequate access for maintenance, operation, and emergency action.

7.2.

Plant sections a.

b. 7.3.

The meaning of ‘sections’ in this context must be clearly understood. 1.

It is not intended to imply that there should be additional spacing between equipment. For example, a multiple reactor system with associated separation equipment when one of the reactors can be shut down for catalyst change with the remaining reactor in operation; in cases like this, the space required depends on the operations to be carried out, any requirement for hot work, and the location of likely sources of release, e.g. sample points.

2.

This does not apply to fired heaters with a common stack. It is acceptable to group together the heaters from more than one section, provided that individual heaters can be positively isolated from each other and any common stack.

If equipment is grouped together, the arrangement should permit, if possible, the use of common structures and maintenance equipment, e.g. a lifting beam.

Separation distances a.

In determining adequate separation distances between the sections of a unit it is necessary to define probable maintenance and access needs and the effect of such activities on adjacent equipment. To meet this objective, and subject to the constraints imposed by other ETPs, PIP PNC00003 provides data on recommended separation distances between process sections. Annex A provides data on clearances around equipment.

b.

Recommended separation distances listed in this ETP and in external industrial standards should be treated as default values that the designer may reduce or extend based upon specific assessment of the risks involved. If possible, the specific risk assessment should:

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7.4.


1.

Address risks external to individual sections of a unit. For example, an external risk analysis might consider hazards to traffic around process facilities and buildings that need to be accessible in the event of an emergency.

2.

Consider risks within individual sections of a unit. For example, an internal risk analysis might assess the degree of confinement and congestion and the potential impact upon blast overpressure during an explosion.

Process units enclosed within buildings Process units or sections of units handling hazardous materials should not be located in fully enclosed buildings.

7.5.

7.6.

Plot drainage a.

The plot shall be graded so that flammable liquid spills do not flow under or collect under process equipment. Grading and paving requirements are defined in GP 04-20, and drainage requirements are in GP 04-10.

b.

The plot shall be graded so that any potential spills or leaks from equipment or piping (e.g. piperacks) containing LNG do not drain to areas where water has collected or pooled such that a Rapid Phase Transition (RPT) is possible.

c.

The location of spillage collection areas depends on the likely spillage, volatility of the liquid and position of permanent ignition sources (i.e. the probability of ignition), and the effect of a pool fire on the equipment. Refer to GP 22-10 for additional requirements for fired heaters.

d.

Equipment containing strong acids or alkalis, or certain toxic, or other corrosive chemicals should be grouped together, provided this is practicable and economical. Such areas shall be graded so that surface drainage can be segregated.

e.

Equipment containing incompatible or highly reactive chemicals should be segregated, provided this is practicable and economical. Such areas shall be graded such that surface drainage from both areas can be isolated from one another.

Special fire risk areas The need for special fire risk areas shall be reviewed to decide if improved equipment design can justify their reduction or elimination. See also API 2218, GP 24-10 and GP 30-85 for normative guidance on special fire risk areas.

7.7.

Plant scale model Layout design may be aided by the use of 3-dimensional drafting packages and/or plastic models. The cost benefit of using these tools should be assessed.

7.8.

Construction considerations a.

If a plot being developed on (or major modification work is being carried out on an existing unit), or adjacent to, existing units, any interaction of the construction and commissioning of the unit(s) of the new plot, and interconnections between the existing units shall be considered. Measures shall be taken to achieve safe construction and commissioning of new plant, and to minimise disruption to, or stoppage of, existing units if this is necessary. Risks from construction activity should be considered and included in the formal risk assessment to compare the relative risk levels of location options.

b.

Points to be considered at an early stage of development, and before the plot selection is frozen, include: 1.

The construction site should be able to be separated from operating units, e.g. by a fence. Ideally the fence should be sufficiently far away to allow a blanket hot work Page 16 of 29

7 September 2005


permit to be issued daily. Consideration must also be given to escape from a fenced site in an emergency. Use of temporary gas detectors can allow early warning for site evacuation.

8. 8.1.

2.

Hot work should be able to be stopped and naked lights extinguished rapidly on the construction site should a major gas release occur. For example, all electric power should be isolated from outside the construction site. The site should be able to be evacuated if toxic release occurs.

3.

A suitable access route to the construction site should be provided for the workforce and construction equipment, e.g. cranes. To avoid possible damage by bulky equipment, the route should avoid roads with overhead pipe crossings or obstructions. Because of the number of vehicles likely to be involved, the route should be away from areas with appreciable pedestrian traffic.

4.

On most construction sites, amenity facilities e.g. canteens, washing and toilet facilities, and a smoking area are required. These should be located away from operating units, and a path between the site and the facilities should be clearly defined.

5.

The movement of construction equipment and especially operation of cranes and lifting gear near operating units can be a hazard. Pedestrian and vehicular access should be kept separate.

6.

The layout and plant location should allow adequate access for operating, maintenance and fire fighting to the existing and new units, and provide for escape routes for emergency evacuation.

Accessways and in plant roads Philosophy a.

Accessways within each unit shall be provided for maintenance and for fire fighting from the roads around the plot. The design of the road layout should consider the plant complexity and the type(s) of fire-fighting appliances (i.e. fire-fighting trucks) likely to be utilized during an emergency. Roads or access over firm ground should be provided to allow fire appliances to approach within reasonable operating distance of the hazard. Access should be kept free of obstruction. In certain circumstances, railway lines may impede access for fire appliances.

8.2.

b.

Emergency vehicle access points should be reviewed, including means of gaining entry where unattended or remotely-operated secure entry systems exist. There shall be at least pedestrian access for fire fighting from all roads around the plot. At least two road approaches shall be wide enough to allow access by emergency equipment to process areas. If access is only possible from two sides, these should, wherever possible, be the longest opposite sides. Normally accessways should be arranged in a rectangular grid pattern so that fire fighting can take place from two opposite sides.

c.

Concrete paving shall be provided in accordance with GP 04-20.

Recommended widths and clearances a.

Minimum widths for personnel accessways, stairways, elevated walkways, platforms, and vehicular accessways shall comply with GP 04-20.

b.

See Annex A for minimum clearance for maintenance access around individual items of equipment.

c.

The use of height clearance indicators/barriers to indicate/prevent potential conflict between vulnerable stationary process equipment/piping above accessways and mobile

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7 September 2005


equipment (e.g. crane jib) should be considered, where necessary, based on a review of the hazards considering type of traffic on the accessway, type of fluid and inventory in the equipment/piperack, and safeguards in place to prevent contact. 8.3.

8.4.

9. 9.1.

Routing a.

Accessways may be run longitudinally under pipe racks, provided that all relevant clearance factors have been considered. However, this shall not apply to roads or an accessway from a road to a unit.

b.

Vehicular accessways shall be as straight as practicable and free of overhead structures except where pipe racks, ducts, and conveyors are located, and should not cross main drainage systems and cable trenches. Equipment shall not protrude into accessways.

c.

Site-run piping and cable trays shall be installed in such a way that they do not affect access.

d.

Process equipment shall be located so that the accessways are not classified as being in Zone 0 or 1 (Class I Division 1) areas, as determined by GP 44 65 (GP 44-60).

e.

Access should take account of the clearance required by the proposed cranes or mobile handling equipment or if there is an economic advantage in a layout which necessitates the use of special equipment.

f.

If practicable and economical, the layout shall permit unrestricted access over minor roads and vehicular accessways for deployment of the largest crane and any other mobile equipment required for maintenance purposes and emergency services. Overhead pipe racks, ducts, and obstructions crossing these roads and accessways shall not interfere with such access.

g.

Where overhead pipe racks, ducts, cables, conveyors, and other obstructions cross a road or accessway, the space available horizontally at grade shall permit access of the largest crane as required for maintenance purposes, so that the crane can be manoeuvred to the required position. When the crane is being used for maintenance work, it shall be possible to raise and extend the jib to the required position without obstruction from overhead pipe racks, cables ducts, or equipment. Minimum vertical clearances are given in Annex A.

h.

Should the above requirements be considered not economical and practicable, details of the equipment required to be removed for maintenance access shall be reviewed.

Access to platforms a.

Access to platforms shall meet the requirements of GP 04-20.

b.

Platform escape routes shall not be adjacent to each other.

c.

Platform escape routes shall not be adjacent to sources of hazard.

Piping References Requirements for process piping systems are covered in GP 42-10 that includes information on layout, access, pipe clearances, and routing. Firebreak walls are referred to in GP 42-10 and GP 04-20.

9.2.

Routing a.

Within a process unit, pipe runs shall be grouped in overhead pipe racks. 1.

The pipe racks should be as straight as practicable.

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7 September 2005

b.

9.3.

9.4.

9.5.

9.6.


2.

Crossings of accessways should be at right angles to the accessway and as far as possible from junctions and bends in the accessway.

3.

Separate, but consistent elevations shall be maintained for both north-south and eastwest pipeway routing.

If pipe leakage during a fire could lead to a major increase in the fire intensity, such pipes should not be located in any special fire risk area (see 7.6). 1.

Such pipes shall include flare lines and pipes connected to 10 m3 (353 ft3) or more of flammable liquid which cannot be remotely isolated.

2.

If this is not practicable, the location of such pipes in the special fire risk area shall have external passive fire protection applied to meet the requirements specified in GP 24-10.

c.

Flammable or toxic liquid/gas piping that remains in service during a process unit outage shall not be routed through that process unit.

d.

Access and space accommodations shall be provided for: 1.

Designated removable pipe sections (e.g. for cleaning).

2.

Inspection needs.

3.

Complying with environmental requirements (e.g. for obtaining Volatile Organic Compound measurements).

Minimum clearances a.

Piping systems shall be designed, and equipment shall be laid out, to provide access by mobile equipment.

b.

Accessways shall be planned accordingly, and minimum clearances for this purpose shall be as described in Annex A.

Piping supports and pipe tracks a.

Piping supports shall not block accessways nor interfere with access.

b.

Piping support layout should allow for removal of pipe work if expected to be necessary for maintenance of equipment.

c.

Outside the plot and in tankage areas, pipes should normally be in pipe tracks at grade level.

d.

The minimum distance between the nearest edge of a pipe track and the toe of a bund (dike) is provided in GP 42-10.

Pipe racks a.

An overhead pipe rack may contain more than one level of piping, provided that replacement of any pipe rack piping is feasible during a unit or section overhaul.

b.

In a multilevel pipe rack, pipes carrying corrosive fluids should be on the bottom level.

c.

In a multilevel pipe rack, utilities should be on the top level of piping, with cable trays above.

d.

Refer to GP 42-10 for more specific pipe rack guidance.

Valve operation a.

Valve actuators and hand wheels shall be located so that they may be conveniently reached when standing at ground level or from a permanent platform.

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7 September 2005

9.7.

b.

Extended spindles or chain-operated valves may be used, but should be avoided if practicable. Chains or extended spindles shall not hang nor be in the path of moving equipment, e.g. cranes.

c.

Refer to GP 42-10 for more specific valve guidance.

Spades (blinds) a.

b. 9.8.


Spading (blinding) positions or other means of positive isolation, e.g. removable spool pieces, that require access during routine operation, shall be accessible without any requirement for scaffolding. This includes: 1.

Spades (Blinds) that require swinging where normal start-up or shutdown routine operations occur frequently, e.g. catalyst regeneration.

2.

Other spading (blinding) positions where economically practicable.

Spading (blinding) requirements are covered in GP 42-10.

Sample points Detailed requirements for sample points and associated drains are specified in GP 42-10.

9.9.

Battery limit isolation a.

It shall be possible to isolate hydrocarbon and utility systems, including steam, instrument air, plant air, nitrogen, process water, and cooling water at each plot without affecting the supply to any other plot.

b.

If the plot contains more than one section, the isolation shall be provided for each section.

c.

The isolating valves shall be readily accessible, and not in an area of special fire risk (see 7.6). They would be isolated in a fire situation to limit hydrocarbon release to the fire and to prevent any loss of containment in a utility system depleting supplies essential to adjacent sections.

10. Equipment 10.1.

Philosophy If available, published equipment spacing tables (such as PIP PNC00003) may be used for guidance, but should be regarded as default values subject to thorough risk and hazard assessments. Further considerations for equipment spacing risk assessments may be found in Guidelines for Facility Siting and Layout by CCPS an AIChE industry technology alliance.

10.2.

Rotating equipment a.

Pumps should be located in the open, at or near grade level. Pumps shall be accessible for operation and maintenance.

b.

Adequately ventilated shelters shall be provided for large machines requiring in situ maintenance (see GP 34-00). Adequate space for lifting and handling facilities for maintenance shall be provided.

c.

Due to asphyxiation risk, nitrogen compressors shall be located in the open or in adequately ventilated houses.

d.

Pumps should be located and specified so that an acceptable NPSH can be obtained without undue elevation of suction vessels or columns. Pumps in flammable or toxic service shall not be located in pits to meet this requirement.

e.

GP 34-00 specifies various pump seal arrangements that have been selected according to the potential hazard in the event of leakage. Pumps meeting the requirements of GP 34-00

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7 September 2005


may be located adjacent to the side of overhead pipe racks, provided that access requirements have been met.

10.3.

f.

Recommended distances from other items of equipment are provided in PIP PNC00003.

g.

Firewalls or fire screens may be used to increase protection of adjacent or overhead equipment, pipe racks, or structures from the effects of a pump fire, provided that access for maintenance and fire fighting is not compromised. It is recommended that these measures (in addition to other active and passive fire prevention/protection means) be supported by a cost benefit analysis.

h.

Pumps, compressors, and blowers in flammable fluid service should be located 15 m (49 ft) or more horizontally from any part of a fired heater, or any process lines that may operate at a temperature of 650°C (1 202°F) or greater.

Fired heaters and high-temperature lines a.

A heater, or group of heaters, shall be located on the periphery of a plot and immediately adjacent to an unrestricted road.

b.

There shall be adequate access for fire-fighting from all sides of a heater and, in the case of a group of heaters, they shall be separated from the remainder of the unit(s) by vehicular accessways on the other three sides of the group.

c.

The layout and design of heaters shall normally be such that the tube removal can be effected by mobile lifting equipment, for which there shall be proper access i.e. the crane location shall not obstruct emergency access roadways. Space requirements for operation and for withdrawal of tubes and burners shall be in accordance with GP 22-10. Minimum clearance guidelines follow:

d.

1.

Horizontal fired heater – tube length plus 3,1 m (10 ft).

2.

Vertical fired heater – not less than 7,6 m (25 ft) wide, for distance equal to 25% of fired heater circumference.

The following equipment and fittings that handle flammable fluids shall be considered to be potential sources of hazard, and shall be located 15 m (49 ft) [or less if justified by risk assessment] horizontally from any part of a heater and any associated electrical equipment housed in industrial type enclosures: 1.

Pumps and compressors in flammable fluid service.

2.

Air-cooled heat exchangers (but also see 10.4).

3.

Sample points.

4.

Hydrocarbon vents and drains open or opened to atmosphere during normal operation. This shall include drains from fuel and pilot gas knockout drums. However, outlets from vents and drains that are opened only during plant shutdown or infrequent maintenance may be less than 15 m (49 ft) from a heater, provided they are closed and plugged during normal operation.

5.

Control valves, meters, and filters on hydrocarbon gas or low flash point hydrocarbon liquid duty.

e.

Process or utility lines that operate at 650°C (1 202°F) or more including transfer lines to or from heaters, and gas turbine exhaust should be considered as permanent ignition sources and taken account of in any risk assessment.

f.

Insulation of lines above 650°C (1 202°F) should cover the lines completely, including flanges and joints. The effect of the insulation on flange bolt temperatures should, however, be checked, and the appropriate grade of bolting selected.

g.

Surface drains shall not be located directly under a heater.

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10.4.

Air-cooled heat exchangers a.

b.

10.5.


The location of air-cooled heat exchangers shall be specifically considered with respect to areas of special fire risk (see 7.6). Such consideration shall include: 1.

The effect of the exchanger on air movement and increased fire spread.

2.

The possibility of failure of exchanger tubes releasing more combustible fluid to the fire.

3.

The design and operating conditions of adjacent process equipment, in particular sealing arrangements of pumps.

4.

The height above any surface that can support a pool fire. See API RP 521 section 3.15.

Minimum distance requirements between air-cooled heat exchangers and pumps: 1.

Air-cooled heat exchangers may be located at a minimum distance from pumps in hydrocarbon service with seals meeting the recommendations of GP 34-00.

2.

For pumps on hydrocarbon duty where seals do not meet the requirements of GP 34-00, a greater distance is required by calculation of the range of a likely flammable release.

3.

The horizontal distance shall be measured at the pump or motor.

c.

Pumps should be located after considering overall piping and plot layout, pump NPSH availability, pump isolation, upstream and downstream inventories, and the consequences of fire spread and air cooler failure.

d.

The use of flanged joints in pipe racks under, or adjacent to, air-cooled heat exchangers should be avoided.

e.

Air-cooled heat exchangers shall be located so that the hot air emitted is not a hazard or an inconvenience to personnel, nor adversely affects the operation of adjacent equipment.

f.

Air-cooled heat exchangers should, if practicable, be at least 15 m (49 ft) horizontally from fired heaters, to minimise the possibility of circulation of hot air.

Shell and tube heat exchangers a.

Shell and tube heat exchangers shall be located so that, when their tube bundles are withdrawn, they do not project into an emergency escape route or any road with unrestricted vehicle access.

b.

Shell and tube heat exchangers shall be arranged so that they can readily be dismantled for cleaning and maintenance.

c.

The spacing between heat exchanger shells shall allow sufficient unobstructed clearance for access for the bundle withdrawal equipment, and to permit access for shell flange gasket renewal. These requirements are specified in GP 26-10.

d.

Additional clearance guidelines follow: 1.

Minimum clearances for exchangers with removable bundles shall be as follows: a)

At channel end: • Longitudinal – tube length plus 3,1 m (10 ft). • Overhead – 3,7 m (12 ft) for exchangers with centreline within 4,6 m (15 ft) of grade. • A clear overhead for exchangers with centreline more than 4,6 m (15 ft) above grade.

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b)

10.6.

2.

Minimum clearances for exchangers with fixed tube sheets are the same as above, except that longitudinal clearance may be provided at either the channel end or the bonnet end.

3.

Shell and tube exchangers shall not be stacked more than two high, except small diameter exchangers if total height above grade/platform does not exceed 3,4 m (11 ft).

Air intakes and discharges a.

Air intakes, including intakes to heating and ventilating systems, air compressors for process, instrument, plant and breathing air, and to gas turbines, shall be located as far as is practicable away from areas where air contamination by dust, or by flammable or toxic material can occur.

b.

Air intakes shall not be located in any area classified as Zone 0, 1, or 2 as defined in GP 44 65 (Class I as defined in GP 44-60), nor located above or below an area classified as Zone 0 or 1 (Class I Division 1).

c.

Air intakes other than for breathing air may be located:

d.

10.7.

At bonnet end: • Longitudinal – 3,1 m (10 ft). • Overhead – 3,1 m (10 ft).

1.

Not less than 3 m (9,8 ft) above a Zone 2 (Class I Division 2) area if the flammable vapour release is heavier than air.

2.

Not less than 3 m (9,8 ft) below a Zone 2 (Class I Division 2) area if the flammable release is lighter than air.

3.

In a Zone 2 (Class I Division 2) area provided dedicated flammable gas detection and protection system is provided.

The location of air intakes shall consider the effects of: 1.

Possible air contamination with dust or with flammable or toxic material.

2.

Additional safety systems, e.g. equipment trips on detection of flammable material in the air intakes.

3.

Reduced pressure on personnel working in the area.

e.

Intakes and discharges shall be separated to prevent cross contamination by recirculation, taking into account natural wind effects. The distance between intakes and discharges shall be not less than 6 m (19,7 ft) unless design provisions can be demonstrated to prevent recirculation.

f.

Air discharges from heating and ventilating systems from enclosed hazardous areas shall be considered as a source of hazardous release and shall be sited accordingly.

g.

Air discharges from heating and ventilating systems, and blow-off facilities associated with air compressors and fans, shall be located so that they do not cause a hazard or inconvenience to personnel nor affect the access to, and operation of, adjacent equipment.

Pressure relief devices If atmospheric discharge from relief devices has been permitted and approved by BP (see 5.2.1.1.d), flammable and toxic atmospheric discharges from the pressure relief devices shall comply with GP 44-70 and the listed guidelines below. a.

In processing installations, pressure relief devices on hazardous duties shall discharge at a point not less than 3 m (9,8 ft) above any platform, equipment, or structure, within a horizontal radius of 30 m (98 ft) measured from the point of discharge.

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11. 11.1.


b.

In processing installations, flammable vapour should discharge at a point not less than 30 m (98 ft) measured in a straight line from any permanent source of ignition.

c.

Vapour from LPG and other low boiling point material storage vessels remote from process areas shall discharge to atmosphere not less than 2 m (6,6 ft) above the pressure relief devices, and not less than 2 m (6,6 ft) above any platform within a 6 m (19,7 ft) radius.

d.

In the case of storage of LPG and other low boiling point materials, there shall be no permanent source of ignition within the radii specified in GP 44-65 (GP 44-60) as measured from the discharge from a pressure relief device.

e.

Flammable vapour should, and toxic vapour shall, discharge at a level not less than 25 m (82 ft) above grade or any main operating floor.

Above-ground bulk storage and transfer areas General a.

Layout and spacing of tanks within a tank farm shall take into consideration the following: 1.

Characteristics of stored product.

2.

Size of tank.

3.

Maximum potential for fire radiation.

4.

Boil over potential.

5.

Business interruption consequences.

6.


7.

Access of fire fighting equipment.

8.

Distances from adjoining properties.

9.

Future expansions.

b.

For additional guidance on the layout of storage facilities, refer to API Std 2610 and IP 19).

c.

Tankage areas should be laid out to meet the requirements of clause 6.1. Any proposal for larger plot sizes shall be subject to BP approval.

d.

Bulk tanks storing hydrocarbons shall be located 76,2 m (250 ft), minimum, from any process unit.

e.

IP 15 classifies liquids as follows based on the closed-cup flash point (except for LPG):

f.

1.

Class 0 – Liquefied petroleum gas (LPG).

2.

Class I – Liquids, other than Class 0, that have flash points below 21°C.

3.

Class II (1) – Liquids that have flash points from 21°C up to and including 55°C, handled below flash point.

4.

Class II (2) – Liquids that have flash points from 21°C up to and including 55°C, handled at or above flash point.

5.

Class III (1) – Liquids that have flash points above 55°C up to and including 100°C, handled below flash point.

6.

Class III (2) – Liquids that have flash points above 55°C up to and including 100°C, handled at or above flash point.

7.

Unclassified – Liquids that have flash points above 100°C.

NFPA 497 classifies liquids as follows:

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11.2.


1.

Class IA – Flammable liquids having flashpoints below 22,8°C (73°F) and having a boiling point below 37,8°C (100°F).

2.

Class IB – Flammable liquids having flashpoints below 22,8°C (73°F) and having a boiling point at or above 37,8°C (100°F).

3.

Class IC – Flammable liquids having flashpoints at or above 22,8°C (73°F) and below 37,8°C (100°F).

4.

Class II – Combustible liquids having flashpoints at or above 37,8°C (100°F) and below 60°C (140°F).

5.

Class IIIA – Combustible liquids having flashpoints at or above 60°C (140°F) and below 93°C (200°F).

6.

Class IIIB – Combustible liquids having flashpoints at or above 93°C (200°F).

7.

Unstable Liquid – A liquid that, in the pure state or as commercially produced or transported, vigorously polymerizes, decomposes, undergoes condensation reaction, or becomes self-reactive under conditions of shock, pressure, or temperature.

8.

Stable Liquid – Any liquid not defined as unstable.

g.

Tanks shall be laid out to provide access for fire fighting. There should be no more than two rows of tanks between adjacent access roads. Tanks of diameter 40 m (131 ft) or greater should be arranged in a single row.

h.

Pumps associated with tankage operations shall not be located inside a bunded (diked) tank compound, and should preferably be grouped together outside the bund (dike) provided this is practicable and economical.

Class I, II, III and unclassified liquids a.

Tank spacing shall comply with whichever is more stringent; NFPA 30, applicable national standards, or the following guidelines: 1.

A minimum spacing of 0,5 of the largest tank diameter (0,5D) shall be provided between any two tanks.

2.

Tanks with 80 m (260 ft) diameter or greater shall have spacing between tanks of at least 2 diameters (2D). However, when the boil-over potential risk (like for crude oil storage) is present, greater spacing distance may be required and should be reviewed by BP Oil Fire Engineering Advisor or BP Group Fire Advisor.

b.

Liquids defined by IP as Class III(1) and unclassified liquids (NFPA Class IIIA liquids stored/handled below their flash point and IIIB liquids) should be stored in a separate tank compound from IP Class I, II, or III(2) liquids (NFPA Class I and II as well as IIIA liquids stored above their flashpoint).

c.

Aboveground tanks for liquids defined by IP as Class I, II, and III(2) (NFPA Class I and II as well as IIIA liquids stored/handled above their flashpoint) shall be completely surrounded by a bund or bunds (dike or dikes). Requirements for the construction of bunds (dikes) are specified in GP 04-20. 1.

The height of the bund (dike) as measured from outside ground level shall be sufficient to afford protection for personnel when engaged in fire-fighting, and the bund(dike) shall be located so that approach can be made to a tank fire to allow use of mobile fire-fighting equipment. The bund (dike) shall not restrict ventilation in the tankage area.

2.

Intermediate walls of lesser height than the main bunds (dikes) may be provided to divide tankage into groups of a convenient size, to contain small spillages and act as firebreaks.

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11.3.

11.4.


d.

Unless otherwise specified by BP and reviewed by BP Oil Fire Engineering Advisor or BP Group Fire Advisor, a separate bunded (diked) compound shall be provided for each tank with a diameter greater than 40 m (131 ft). For tanks of diameter less than or equal to 40 m (131 ft), individual bunded (diked) compounds are not required.

e.

In no case shall the number of tanks in any bunded (diked) compound exceed 6.

f.

The combined capacity of multiple tanks in a single bund (dike) should not exceed 60 000 m3 (2,1 E6 ft3) regardless if the tanks are conventional fixed roof tanks or floating roof tanks (e.g. three 20 000 m3 (0,7 E6 ft3) or two 30 000 m3 (1,1 E6 ft3) tanks in a single bund though at the maximum limit would be allowed). Early discussions with local safety and environmental regulatory agencies may further influence bund (dike) capacity calculations.

g.

The net capacity of a bunded (diked) tank compound shall be equivalent to the capacity of the largest tank in the compound plus 10%. The net capacity of a bunded (diked) tank compound shall be calculated by deducting from the total capacity: 1.

The volume of all tanks, other than the largest, below the level of the top of the bund (dike).

2.

The volume of all intermediate bunds (dikes).

h.

If there is an absolute requirement to deviate from the guidelines in clause 11.2, advice should be sought from the BP Oil Fire Engineering Advisor or BP Group Fire Advisor.

i.

For liquids which can cause damage to the environment or personal injury including IP Class III(1) (NFPA Class IIIA liquids stored/handled below their flash point), unclassified liquids (NFPA Class IIIB) and toxic liquids, a bund (dike) compound shall be provided as defined in clause 11.2 for IP Class I, II, and III(2) or other means of secondary containment to prevent threat to public health, personnel, water supplies or other environmental damage. This includes but is not limited to storage of acid and caustics.

Pressurised LPG storage a.

LPG storage shall be laid out in accordance with API Std 2510 or equivalent European code, except that BP will specify vessel separation.

b.

The risk to personnel (both onsite and offsite) from thermal radiation effects (e.g. from torch fires, flash fires, pool fires and BLEVEs) should be assessed and compared with the appropriate criteria.

c.

As guidance in the absence of formal risk calculations thermal radiation at the plot boundary, in the event of ignition of the leakage from a single relief valve or from a fire in a spill-containment area, should not exceed 4,7 kW/m2 (1 490 Btu/hr-ft2). The radiation may be calculated using the method in API RP 521 and assuming that: 1.

Fraction of heat liberated F = 0,3

2.

Wind speed = 2 m/s (6,6 ft/s)

LNG storage LNG storage tank layout shall comply with either EN 1473 or NFPA 59A.

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Annex A (Normative)

Guidance on clearances A.1.

General a.

A.2.

1.

Projecting piping.

2.

Valve spindles (valve wheels).

3.

Instrumentation.

4.

Instrument air manifolds.

5.

Local panels.

6.

Transducer stations.

7.

Pneumatic and electrical junction boxes.

8.

Grouped steam tracing supply and condensate manifolds.

b.

A minimum of 1 m (3,3 ft) clear working spaces shall be maintained around equipment that requires frequent servicing such as pumps, exchangers, control valves, instruments, tower manways, etc. Also refer to A.3.c for more stringent minimum horizontal clearances for specific applications.

c.

Horizontal and vertical clearances shall meet or exceed those recommended by equipment suppliers for maintenance and operations.

Vertical a.

b.

A.3.

Items such as the following shall not block operating aisles or maintenance access.

Overhead clearances shall not be less than: 1.

3,7 m (12 ft) if carry deck crane access is required.

2.

4,6 m (15 ft) if cherry picker (13,6 to 16,3 t [15 to 18 ton] crane) access is required.

3.

3,1 m (10 ft) if 1,8 to 2,7 t (2 to 3 ton) forklift truck access is required.

4.

3,7 m (12 ft) for main pipe racks.

5.

2,2 m (7 ft) from grade or elevated platform for personnel passageway.

6.

3,1 m (10 ft) from pavement for secondary roads (cars, pickups, no mobile equipment).

7.

4,9 m (16 ft) from pavement for main roadways without crane access.

8.

5,5 m (18,0 ft) from pavement for main roadways and, if necessary, over accessways for heavy equipment. However, vertical clearance for crane access at main OSBL roadways and ISBL accessways shall be obtained from BP.

Overhead clearance from top of rail for railroads to be confirmed by national (i.e. federal) and local railway clearances requirements as these vary from site to site.

Horizontal a.

Main accessway horizontal clearance for mobile equipment shall be obtained from BP but shall not be less than:

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1.

6,1 m (20 ft).

2.

3,1 m (10 ft) if mobile equipment is to service a specific piece of process equipment and the mobile equipment can operate “straight-in” (no turns).

b.

Minimum rail siding clearance for railroads must comply with national (i.e. federal) and local railway clearances requirements as these vary from site to site.

c.

Minimum horizontal clearance to piping, equipment, and instrumentation shall be as follows unless otherwise approved by BP: 1.

1,5 m (5 ft) for aisles at equipment and machinery.

2.

1,2 m (4 ft) for operating and maintenance areas at grade.

3.

1,2 m (4 ft) for workspace on platforms servicing the heads of shell/tube exchangers mounted on a structure. Also refer to clause 10.5.

4.

0,9 m (3 ft) for workspace on platforms servicing manways, in addition, the centre line of the manway should be at an elevation of 1,5 m (5 ft) from the platform.

5.

2,1 m (7 ft) for workspace around compressors, turbines, and large motors shall be provided for operating and maintenance clearances to handle casings, rotors, crankshafts, flywheels, etc. This minimum spacing shall be validated by the equipment supplier and approved by BP. Note Clearances shall be measured from the furthest projection on equipment, including associated pipe work with its flanges and insulation boxes, filters, valves in their open position, drains, cabling, instruments, etc., between grade and 2,0 m (6,6 ft) above grade.

Page 28 of 29

7 September 2005


Bibliography [1]

AIChE “Guidelines for Facility Siting and Layout”.

[2]

LASTFIRE Study (Large Atmospheric Storage Tank Fire Project) "Atmospheric Storage Tank Study for Oil and Petrochemical Industries Technical and Safety Committee Singapore" by Technica (dated 1990) (link http://hse.bpweb.bp.com/hse/default.asp?subcat=394).

[3]

"Guide to Fire Protection, Detection, Suppression and Emergency Response on BP LNG facilities" by BP Group Technology (contact Richard Coates for document status).

Page 29 of 29

GP 44-10 Plant Layout

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