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PREPARED
BY PTT PUBLIC COMPANY LIMITEDCHECKED
BY ONSHORE COMPRESSOR STATION 4
PROJECT
APPROVED
BY
CERTIFIED
(PTT)
REV.
NO.
DATE REVISED
BY
APPROVED
BY
DESCRIPTION
D118-Feb-
08ISSUED FOR ITB
D2 1-Jul-08 REVISION ISSUED FOR ITB
SPECIFICATION FOR
PIPING GROUP EQUIPMENT SPACING
SPC-0804.02-50.03 REV.D2
TOTAL 41 PAGES
AREA CODE OF SITE LOCATION
GENERAL AREA: 010
.
PTT PLC. CONTRACT NO. PTT PLC. PROJECT NO.
0804.02
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CONTENT
SECTION
1.0 SCOPE ..................................................................................................... 3
2.0 GENERAL CONSIDERATIONS ...................................................................... 3
3.0 DEFINITIONS ............................................................................................ 4
4.0 STANDARDS AND GUIDES......................................................................... 5
5.0 SPACING OF UNITS AND AREAS ................................................................ 6
6.0 ON SITE SPACING....................................................................................12
7.0 OFFSITE SPACING....................................................................................22
8.0 TANKAGE................................................................................................27
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1.0 SCOPE
The scope of this standard is to define the basic design, equipment spacingcriteria and standards to be used in the layout of plant and equipment.
The recommendations are based on current practice within the industry and are
intended, as a minimum, to satisfy the requirements of all relevant Government
safety recommendations.
Where applicable this standard is to be read and utilised in conjunction with
relevant National mandatory standards, listed codes and regulations which also
apply to the location of the project.
In the event of any conflict, Contractor shall seek clarification from the Clientbefore proceeding. Generally, the most stringent requirements shall apply.
This standard is not applicable for the following: -
Toxic Materials Handling Plant
Explosives Plant
Nuclear Plant
Pharmaceutical Plant
Equipment within Enclosed Buildings
Offshore Facilities
Well Drilling Sites for Oil or Gas
2.0 GENERAL CONSIDERATIONS
The objective of the spacing recommendations is to ensure that maximum
economical use is made of available plot areas, compatible with the safety ofpersonnel and vulnerability of plant.
In achieving this end, consideration shall be given to:
a) Accessibility for normal operation and maintenance
b) Accessibility for fire fighting
c) Accessibility for emergency shutdown
d) Accessibility for evacuation of personnel
e) Segregation of high-risk facilities and sources of ignition
f) Protection of critical emergency facilities
g) Protection of adjacent facilities in event of fireh) Security of installations from outside hazards
i) Minimising danger and inconvenience to personnel and property
beyond the boundary fence.
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j) Ergonomic Factors
k) Escape access ways shall be as straight and obstruction free as
possible.l) Hazardous area classification
m) Ensuring that flammable vapour generated from one facility will
diffuse to a concentration well below the lower explosive level (LEL)
before it reaches any other facility or area where a source of ignition
may exist.
n) Providing a reasonable degree of protection (distance) against heat
radiation
2.2 Circumstances will arise where it will be difficult to adhere to the minimum
spacing requirements; e.g. where there are severe limitations on plot
availability. In such cases a reduction of minimum spacing (less than 10%) shall
only be acceptable, after agreement with PTT/CONSULTANT. Any reductions in
the proposed distances between equipment shall be subject to a Risk
Assessment or Hazard Analysis. In this case extra safety features such as
Firewalls, Sprinklers, Emergency Shutdown Facilities etc., shall be required to
be incorporated into the design in order to compensate for the reduction in the
distances between the equipment. Such reductions shall not be made without
prior reference to PTT/CONSULTANT.
2.3 Other factors may require spacing greater than minimum recommendation of
this Standard. In this category consideration should be given to:
Proximity of adjacent property and the consequential environmental and public
relations effects.
Special process hazards, which may necessitate increased spacing.
Special plant maintenance or installation considerations
Future development plans both inside and outside the boundary fence.
Topographical features of site and direction of prevailing winds
Political security factors.
Special hazard zoning plans for existing plant areas.
3.0 DEFINITIONS
The following definitions are used throughout the standard.
3.1 Flash Point
The flash point is the lowest temperature at which a product gives off sufficient
vapour to form a mixture with air that can be ignited by a flame or spark.
3.2 Auto Ignition Temperature (AIT)
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The auto-ignition temperature is the temperature at which a product will burn
without application of any other form of ignition.
The AIT of most petroleum products is between 250C and 500C. In general
the AIT of petroleum hydrocarbons decrease with higher boiling fractions
whereas flash points increase.
3.3 Sources of Ignition
Possible sources of ignition include the following:
3.3.1 Electrical
Sparks or arcs may occur when current carrying contacts are separated or
through static electricity discharge.
3.3.2 Naked Lights
E.g. fired heaters, fires, smoking, hot work, gas welding, etc.
3.3.3 IC Engines
Spark-ignition systems, exhaust hot spots.
3.3.4 Spontaneous Combustion
Pyrophoric materials, vapour leakage at temperatures above AIT.
3.3.5 Frictional Ignition
Grit blasting, power tool grinding, mechanical failure of rotating machinery.
3.3.6 High Temperature Surfaces
Transfer lines, HP steam lines, and other hot surfaces.
4.0 STANDARDS AND GUIDES
Philosophy on plant layout is contained within various standards and guides,
including;
SPC-0804.02-50.01 Design Instruction for Piping Arrangement.
Noise Control Eng. Std.
Institute of Petroleum Model Codes of Safety Practice, Part 3
LP GAS Association Code of Practice 1
Institute of Petroleum Model Codes of Safety Practice, Part 9, LPG
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Area Classification Code for Petroleum Installations,(IP15) Model Code of
Safe Practise in the Petroleum Industry Part 15
NFPA-30 (Flammable & Combustible Liquids Code)
NFPA-58 (Storage and Handling of LPG)
NFPA-59 (Storage and Handling of LPG)
NFPA-59A (Storage and Handling of LNG)
Fire Fighting Systems
European Standard EN 1473, Installation and equipment for LNG Designof onshore installations.
European Model Code of Safe Practices in the Storage and Handling of
Petroleum Products. Part 1, Operations.
API Standard 2510 Design and Construction of LPG Installations
Thai Fuel Oil Storage Act 2474
Announcement of the ministry of liquid petroleum gas containment
Note: Reference should be made to these documents when producing the
optimum layout of the relevant plant facilities.
5.0 SPACING OF UNITS AND AREAS
Fig.1 Show a typical overall PLOT PLAN
5.1 Process Unit
A process complex consists of a combination of plants, each carrying out a
specific processing duty. These plants are defined as PROCESS UNITS.
Equipment items within the process unit limits are referred to as on-site
equipment. On-site Spacing Chart, Fig. 4, gives the recommended spacing
between these items of equipment.
Equipment limits are determined by an imaginary line drawn around the outer
edge of equipment within the Process Unit.
5.2 Process Area
Several process units may be combined to form a PROCESS AREA. These unitsmay be integrated, i.e. by no spacing between units other than basic equipment
spacing, or may be laid out as separate units with spacing between equipment
limits (as defined above) based on fire fighting access, process hazard or
separate shut-down requirements; depending on overall plant philosophy.
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5.3 Process Block
A number of process areas may be combined to form a PROCESS BLOCK. Fig.2 indicates an example of a Process Block showing the arrangement of a
Process Unit (integrated and separate) and Process Areas within the block. The
basic minimum spacing between Units and Areas are given on Fig. 2.
5.4 Tankage Block
Fig. 3 shows the basic minimum spacing between bunded areas for a
TANKAGE BLOCK.
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Fig. 1 Typical Overall Plot Plan.
FIRE TRAINING
EFFLUENT
TREATMENT.UTILITY AREA
STORM
DRAIN
PROCESS
UNITS
ADMIN
BLDG.
FUTURE PROCESS UNITSFUTURE EXPANSION
CRUDE OIL
TANKAGE
GRADE
PIPETRACK
LPG
SPHERES
INTER-
MEDIAT
TANKS
PROCESS
BLOCK
FUTURETANKAGE
TANKAGE
BLOCK-PRODUCT
STORAGE
ELEVATED
PIPERACK
FUTURE
UTILITY
AREA
REFINERY
BOUNDARY
FENCE LINE
GATE
HOUSE
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Fig. 2 Example of a Process Block
Shows the process block divided into areas: and an area divided into units. Also showthe dimensions of the clearances required.
10m
C
10m
B
EQUIPT.
LIMITS
ALL
EQUIPT
WITHIN
LINES
ACCESS
EQUIPMENT LIMIT
SINGLE LARGE UNIT
INTEGRATED UNITS
(No Physical Separation)
AB
C
ACCESS
SEPARATE
UNIT
10m 50m 50m 50m15m 15m
10m
80m
80m
60m
30m
30m
A
RESTRICT
TO 300m
(approx)
UNIT
LIMIT
SEPARATE
UNIT
UNIT
LIMIT
C
EQUIPT.
LIMITS
PROCESS AREA
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Fig. 3 typical Tankage Block
Dimensions are from the inside of the top bund wall. Bund should not be less than 15
m. from the outer boundary of the installation or the protection belt. This is to allow
for an access for firefighting and also to create a safe distance from the boundary.
30m 30m
ACCESS
ROAD
30m
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Fig. 4 On Site Spacing Chart
This chart to be used with On-site spacing guide.
Note: All distances in metres
N.A. Not applicable.
X Provide spacing based on access for operation and maintenance.
Y As required see On-site spacing guide.
Basic spacing is the recommended distance required between a given facility and
other general processing equipment. This spacing is not required between items
in similar service, (i.e. pumps and spare etc).
See notes in section 7.1: On-site spacing guide.
7.5 7.5 7.5 7.5
3 4.5 4.5 1.5 4.5
7.5 7.5 7.5 N.A. 15 N.A. 7.5 7.5 7.5 7.5 X X X N.A. 7.5 X X
EMERGENCY VALVES FOR SHUT-OFF,
ISOLATING, SNUFFING ETC
X
EMERGENCY VALVES ETC
X
7.5
4.5
4.5 4.5 1.5 3 6 4.5 3 1.5 4.5 4.5 X 7.5 4.5 4.5
ON SITE PIPE RACKS
MAIN EQUIPMENT STRUCTURES
X
15
15
30
X
10.5
4.5 4.5 X
15 15 15
22.5 X 4.5 X X 15 15 4.5 3 7.5 X X 30
22.5 15 15 15 15 15 15 15 15 15 X X X
15 15 15 22.5 15 15 15 15 15
30 30 30 30 30 30 30 30 30
4.5 4.5 X X X 4.5 X X 4.5
4.5 7.5 10.5 22.5 15 4.5 10.5 10.5 7.5
15 15 15 15 15
30 30 30 30 30
X 4.5 X X X
15 4.5 10.5 X X
15
X X
15 X
X X X
X X
X
7.5 7.5 7.5 7.5 22.5 15
3 4.5 7.5 3 22.5 7.5
4.5 4.5 7.5 4.5 22.5 15
7.5 7.5 7.5 22.5
4.5 3 3 15
4.5 4.5 4.5 7.5
15 15 15 15 22.5 15 15 15 15 30
15 4.5 7.5 15 22.5 15
3 4.5 7.5 3 22.5 7.5
1.5 4.5 7.5 1.5 22.5 7.5
7.5 15 15 Y
4.5 3 X
4.5 1
15 7.5 7.5
15 4.5 1
15 1.5
X
X
4.5 4.5 7.5 4.5 22.5 15
7.5 15 15 7.5 22.5 X
22.5 22.5 22.5 22.5 10
1
1.5 4.5 7.5 1.5
7.5 7.5 1.5
4.5 1.5
3
ELECTRICAL SUBSTATION
UNIT CONTROL HOUSE
CENTRAL CONTROL HOUSE
EQUIPMENT HANDLING NON-
FLAMMABLES
COMPRESSOR DRIVERS (OTHER THAN
STEAM OR MOTOR)
GAS COMPRESSORS AND EXPANDERS
HANDLING FLAMMABLE MATERIALS
PUMPS HANDLING FLAMMABLE
MATERIALS
PUMPS ABOVE AIT
COOLING TOWERS
FIRED HEATERS
AIR FIN COOLERS
EXCHANGERS OPERATING BELOW AIT
EXCHANGERS OPERATING ABOVE AIT
BLOWDOWN AND DISENGAGING DRUMS
ON-SITE PRESSURE STORAGE VESSEL
DRUMS
REACTORS ABOVE AIT INTERNALLY
INSULATED
REACTORS ABOVE AIT EXTERNALLY
INSULATED
N.A.
15
15
30
X
10.5
7.5
3
4.5
15/30
15
3
1.5
4.5
7.5
22.5
1.5
7.5
4.5
1.5
RT1
RR1
RS1
RQ1
RP1
RO1
RN1
RM1
RL1
RK1
RJ1
RI1
RH1
RG1
RF1
RE1
RD1
RC1
RB1
RA1
RU1
RV1
22.5
ITEM
REF.
BASIC SPACING
TOWERS
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6.0 ON SITE SPACING
The recommended spacing for on-site equipment is indicated in On-site
Spacing Chart Fig. 4.
The information on this chart is supplemented by explanatory notes which are
contained in Section 7.1 On-Site Spacing Guide.
It is essential that reference is made to Section 7.1 when using On-Site
Spacing Chart Fig. 4.
Against each type a basic spacing dimension is quoted. This basic spacing is
the recommended distance in metres between the item and other general
process equipment. The recommended spacing between different items is
given at the intersection of the horizontal line for one item and the vertical linefrom another. In general, this shall be the greater of the basic spacing
dimensions for the two items. Explanatory notes can be found in Section 7.1.
The spacing between two similar items is given in the first box adjacent to the
item. Note that basic spacing is not required between items in the same
service.
6.1 On-Site Spacing Guide(Use with on-site spacing chart Fig. 4)
6.1.1 Ref.: RA1 Towers
(Basic Spacing 1.5 metres)
The basic spacing of 1.5 metres provides access for operation and
maintenance. The distance between two towers is twice the basic dimension.
This provides some additional access for fire fighting and clearance for non-
coincidental platforms.
6.1.2 Ref. RBI Reactors
(Above AIT externally insulated) (Basic spacing 4.5 metres)
The basic spacing of 4.5 metres provides access for fire fighting and minimises
damage to other equipment. The external insulation protects the reactor shell
from fires on other equipment.
Reactors may be grouped together; in which case operational and maintenance
access of 1.5 metres between shells is satisfactory.
Reactors operating below AIT may be regarded as drums, i.e. drum spacing
recommendations will apply (see Ref. RD1).
Spacing from Ref. RF1 is in excess of the greater basic dimension as theReactor is regarded as high-risk equipment.
Since the Reactor is operating above AIT, other sources of ignition are not a
spacing consideration and basic reactor spacing of 4.5 metres will apply, e.g.
items Ref. RJ1 and R01.
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6.1.3 Ref. RC1 Reactors
(Above AIT internally insulated. Basic spacing 7.5 metres)
The basic spacing of 7.5 metres provides access for fire fighting, minimises
damage to other equipment in event of reactor fire, and protects exposed shell.
N.B. Internally lined reactor shells are more susceptible to fire damage than
unlined vessels. Reactors may be grouped together; in which case operational
and maintenance access of 1.5 metres between shells is satisfactory.
Reactors operating below AIT may be regarded as drums, i.e. drum spacing
recommendations will apply (see Ref. RD1).
Spacing from RF1 is in excess of the reactor after basic dimension as the
reactor is regarded as high-risk equipment.
Since the reactor is operating above AIT, other sources of ignition are not a
spacing consideration, basic reactor spacing of 7.5 metres will apply, e.g. items
RJ1/R01.
Spacing from Refs. RP1, RT1, RU1 these items are not regarded as fire
hazardous the spacing of 4.5 metres will give these items protection in the
event of reactor fires.
6.1.4 Ref. RD1 Drums
(Basic Spacing 1.5 metres)
The basic spacing of 1.5 metres access for operation and maintenance. Spacing
from RU1 is the basic drum spacing as the pipe rack is not considered fire
hazardous. Drums should not be located under pipe racks.
6.1.5 Ref. RE1 On-site Pressure Storage Vessels
(Basic Spacing 22.5 metres)
The basic spacing of 22.5 metres minimises exposure of unit equipment to a
potential source of severe fire, and blast damage in the event of an explosion.
Pressure storage in on-site locations shall be avoided wherever possible.
It is sometimes necessary, e.g. in solvent propane dewaxing and deasphalting
units to provide pressure storage facilities on-site; in such instances the
inventory shall be held to a minimum and the storage vessel located at the unit
battery limit and as far as possible from fired heaters and other source of
ignition.
For pressure storage vessels, in the same service provide a minimum of onediameter between shells for operational and maintenance access.
Spacing from RU1 pipe racks is not considered as fire hazardous- spacing of
4.5 meters affords protection to these items in the event of storage vessel fire.
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6.1.6 Ref. RF1 Blow-down and Disengaging Drums
(Basic spacing 7.5 metres)
The basic spacing of 7.5 metres provides protection to the Drum in the event of
fire within the unit.
For high-risk equipment the spacing shall be increased to 15 metres. High risk
equipment includes reactors, exchangers and pumps, operating above AIT, fired
heaters, gas compressors and expanders, and their drivers, e.g. items Ref. RB1,
RC1, RG1, RL1, RN1, R01.
Spacing from Ref. RU1 pipe racks are not regarded as fire hazardous
spacing of 4.5 metres affords protection to the pipe rack in the event of
blowdown drum fire.
6.1.7 Ref. RG1 Exchangers
(Operating above AIT) (Basic spacing 4.5 metres)
The basic spacing of 4.5 metres minimises damage to other equipment in event
of fire. Exchangers operating above AIT are high-risk items with greater
probability of fire than for exchangers operating below AIT.
Exchangers above AIT in the same service, i.e. connected by a common
process stream, may be spaced 1.0 metres apart; for other exchangers basic
spacing of 4.5 metres shall apply.
Spacing from Ref. RJ1 since the fluid in the exchanger is already above its
AIT, the fired heater, in this case, does not represent a source of ignition.
However, a heater fire is considered likely to be more severe than other plant
fires, so spacing greater than basic is applied to minimise damage to the
exchanger in the event of a heater fire.
Spacing from Ref. R01 since the fluid in the exchangers is above its AIT, the
compressor driver does not represent a source of ignition. Therefore,
exchanger basic spacing of 4.5 metres applies.
Spacing from RF1 is in excess of the greater basic dimension as the exchanger
(above AIT) is regarded as a high-risk item.
Spacing from ref. RP1 protects equipment from a high fire risk system.
6.1.8 Ref. RH1 Exchangers
(Operating below AIT) (Basic spacing 1.5 metres)
The basic spacing of 1.5 metres provides access for maintenance and
operation. There are no limitations on spacing exchangers from pipe racks exchanger spacing applies.
6.1.9 Ref. RI1 Air Fin Coolers
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(Basic spacing 3 metres)
Air fin coolers by virtue of their design and operations are particularly vulnerableto fire hazard.
For this reason grade mounted units isolated from other equipment are
preferred. However, because of restrictions on area availability, it is common
practice to mount air fin coolers on top of the pipe rack. In such cases
consideration shall be given to the following:
Air fin coolers shall not be mounted over pumps, compressors, drums or heat
exchangers, containing flammable materials.
There shall be no flanges or valves in any hydrocarbon lines on the rack
beneath an air fin cooler.
Horizontal spacing requirements of on site spacing chart, Fig.4, shall be met.
Support legs for the air fin cooler shall be fireproofed in accordance with the
relevant Project Engineering Standard.
Access shall be provided for tube bundle removal by mobile equipment.
The basic spacing of 3.0 metres (horizontal) minimises exposure to fire hazard
air fins are more vulnerable to fire damage than shell and tube exchangers.
Ref. RU1 the basic spacing of 3.0 metres is applicable to grade mounted air
fin coolers only.
6.1.10Ref. RJ1 Fired Heaters
(Basic spacing 15 metres)
A fired heater by its nature is a permanent source of ignition while operating. A
heater fire is likely to be of maximum severity. The basic spacing of 15 metres
separates equipment handling flammable vapours from a permanent source of
ignition and affords protection in the event of a major heater fire. Heater
location will sometimes be predetermined by the requirement of grouping to a
common stack with heaters from other process units.
Where such restrictions are not applied, the heater location shall be selected on
the windward side of the unit with reference to the prevailing wind, close to the
battery limit and as far as practicable from other equipment. Consideration
shall also be given to the proximity of plant and equipment outside the unit
battery limit.
When the heater has an individual stack, the top of the stack shall be at least 3
metres higher than equipment within a horizontal distance of 15 metres and atleast 3 metres higher than any operating platform within a horizontal distance
of 65 metres.
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Ref. RJ1 - If all heaters in a group shutdown together at plant turnaround,
spacing between shells can be for normal maintenance only. If heaters are
required to shutdown individually, spacing of 7.5 metres between shells isrequired for LP operation (less than 7 kg/cm2g) and 15 metres between shells
for HP operation (7 kg/cm2g and above).
Refs. RB1, RC1, RG1, RL1 are items operating above their AIT and in these
cases the fired heater is not considered to be the primary source of ignition,
spacing is based on affording protection in the event of heater fire.
For reformer heater/reactor installations, where vapour only is present in heater
tubes and reactors, spacing may be further reduced to 3 metres in the case of
Ref. RB1 and 5 metres in the case of Ref. RC1.
Ref. RN1 the compressor area is regarded as a special risk area in view of the
potential release of large vapour quantities. Spacing greater than the basic
dimensions are required.
Ref. R01 the compressor driver is not considered a source of ignition in this
case. The spacing of 7.5 metres minimises damage to the compressor driver in
the event of heater fire.
Ref. RP1 a spacing of 4.5 metres minimises damage in the event of the
heater fire. For equipment higher than 3 metres, spacing shall be increased to
7.5 metres from heaters with liquid in their tubes. Reduced spacing is
permitted because there is no flammable material release in the event of
damage.
Ref. RU1 because of severity of heater fire, spacing to pipe racks is greater
than basic.
N.B. This does not apply to heaters own pipe rack
6.1.11 Ref. RK1 Cooling Towers
(Basic spacing 15 and 30 metres)
Basic spacing of 15 metres applies to equipment lower than the cooling tower;
basic spacing of 30 metres to equipment higher than the cooling tower.
The cooling tower becomes a source of hazard in the event of tube failure in a
water cooler. Basic spacing provides for dispersion of hazardous vapours,
minimises corrosive effects of spray impingement and visibility problems from
exhaust plume.
The cooling towers shall be located on the leeward side of a process unit with
reference to the prevailing wind.
Ref. RU1 the factors above are not consideration in the case of a pipe rack.Pipe rack basic spacing will apply.
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Ref. RU1 is not a hazard producing item. The basic spacing of 4.5 metres
provides protection in the event of compressor fire.
6.1.15Ref. R01 Compressor Drivers(Other than steam or motor)
(Basic spacing 10.5 metres)
Basic spacing is not applicable between Compressor and driver. Gas turbine,
gas engine or internal combustion engine drivers are sources of ignition. Basic
spacing of 10.5 metres affords safe spacing from a source of ignition.
For items RB1, RC1, RG1, RL1, which are operating above AIT, the driver is not
considered to be the primary source of ignition. The basic spacing for these
items therefore applies.
Ref. RJ1 spacing of 7.5 metres protects driver in event of heater fire.
Ref. RF1 spacing greater than basic provides additional protection to critical
item.
Ref. RU1 the pipe rack is not a hazard rack basic spacing applies.
6.1.16Ref. RP1 Equipment Handling Non Flammables
(Spacing provided for operational and maintenance access)
Ref. RB1, RC1, RG1, RJ1, RL1 spacing of 4.5 metres provides protection to
equipment in the event of fire at likely sources of ignition.
6.1.17Ref. RQ1 Central Control House
(Basic spacing 30 metres)
Basic spacing of 30 metres affords protection to personnel and critical control
equipment from plant fire or explosion hazard. Consideration shall be given in
special circumstances to blast-resistant design of building.
Ref. RU1 on site pipe racks shall not be nearer than 30 metres to the Control
House. Provided lines are fully welded with no valves or flanges, a pipe rack
may be brought to 7.5 metres from one side only of a central control house.
6.1.18Ref. RR1 Unit Control House
(Basic spacing 15 metres)
The location of a unit control house is obviously less critical than a centralcontrol house. It should be located at the battery limit adjacent to a roadway.
Basic spacing minimises risk to personnel and equipment in the event of a unit
fire.
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Ref. RU1 pipe rack basic spacing applies provided lines are fully welded
without valves or flanges.
6.1.19Ref. RS1 Electrical Sub-station
(Basic spacing 15 metres)
Electrical sub-stations are located close to the battery limit and near to a
roadway. The basic spacing is fixed by Area Classification considerations and
provides protection to the electrical equipment in the event of unit fire.
Ref. RU1 pipe racks do not present a major hazard. Basic rack spacing
applies.
6.1.20Ref. RT1 Main Equipment Structures
(Basic spacing not applicable)
Sufficient spacing shall be allowed from ignition sources of high-risk RC1 items
to prevent damage to structure in event of fire or explosion. Items RB1, RC1,
RE1, RG1, RJ1, RL1, RN1 are in this category. In most other cases the
equipment in the structure will govern its location with respect to other
equipment.
6.1.21 Ref. RU1 On-site Pipe Racks
(Basic spacing 4.5 metres)
Pipe rack basic spacing gives protection to the pipe rack in the event of
equipment fires within a process unit. Items Ref. RB1, RC1, RE1, RG1, RK1,
RN1 and R01 are located on this basis.
Item Ref. RJ1 fired heater is a possible source of a major fire. Spacing
greater than basic is required in this case.
N.B. This limitation does not apply to the pipe rack serving the heater area.
The pipe rack in itself is not considered highly hazardous. In general equipment
which is not hazardous may be located on access and operability considerations
relative to the pipe rack. Items Ref. RA1, RD1, RH1, RI1 (grade mounted) are
in this category.
In special cases where the hazard from the pipe rack shall be minimised, fittings
and flanges which could be sources of leakage shall be eliminated from the pipe
rack in the vicinity, e.g. from pipe racks under air fin exchangers and from pipe
racks in the vicinity of control houses, i.e. items RI1, RQ1 and RR1.
Pumps are also considered as a special case as, for layout purposes, access and
operability, it is usual to have pumps in close proximity to the pipe rack, e.g.items Ref. RL1 and RM1 spacing is horizontal distance from pump stuffing
box to edge of pipe rack.
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6.1.22 Ref. RV1 Emergency Valves for Shut-off, Isolation, Snuffing, etc.
(Basic spacing 7.5 metres)
The basic spacing is the distance between the emergency valve and the
equipment it controls. It can be located adjacent to other equipment.
Ref. RE1 and RJ1 are exceptionally hazardous items. The basic spacing for
these items there applies.
Where it is necessary for reasons of plant layout to locate emergency shut-off
valve manifolds closer to a heater than 15 metres, a fire wall shall be provided
between the manifold and the heater at a minimum distance of 7.5 metres from
the heater.
6.1.23 Roads of width 6 metres or more
Maintain a minimum of 10m between roads and any hydrocarbon containing
equipment.
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Fig. 5 Off-Site Spacing Chart
30
45
15
45 30 60 45 45 45 45 45 4.5
45 45 45 45 45 45 45 45 4.5
7.5 15 15 7.5 7.5 7.5 45 N.A. 4.5
45 45 30 60 15
45 45 30 60 30
45 N.A. 15 N.A. N.A.
30 N.A.
X
30 7.5 30 60 7.5 7.5
30 45 15 15 45 45
45 X 30 60 X X
7.5 60 45 7.5
30 45 15 4.5
X 45 45 4.5
45 60 30 60 45 45 45 45 45 4.5
6 15 4.5 X 7.5 4.5
45 60 30 60 45 45
45 45 45 60 45 45
4.5 45 15 N.A.
45 45 N.A.
45 N.A.
60 N.A. 45
15 45 X
45 N.A.
N.A.
15
30 X 15 60 X X
30 X 15 60 X N.A.
X X 45 60 X
X
60 60 60 N.A.
30 45 X
30 X
X
FACILITIES FOR HEAT SENSITIVE
MATERIALS EG TEL. & TML.
MAIN EFFLUENT TREATMENT
PLANT RAIL FACILITIES
RAILWAY MAIN LINES
MAJOR PUMP AREAS
BOUNDARY FENCE
PROCESS AREAS
MAJOR OFFSITE PIPE TRACKS
LOADING RACKS FOR LOW FLASH
PRODUCTS
FIRE TRAINING AREA
MAIN FIRE WATER PUMPS
FIRE STATION
MAIN ELECTRICAL SUB-STATIONS
JETTIES (LOADING ARM MANIFOLD)
COOLING TOWERS
BUILDINGS, MAIN OFFICES, WORK-
SHOPS, LABORATORIES, ETC
30
45
15
60
15
45
45
4.5
45
45
45
45
45
60
15/30
45
30
RR2
RQ2
RP2
RO2
RN2
RM2
RL2
RK2
RJ2
RH2
RG2
RF2
RE2
RD2
RC2
RB2
RA2
This chart to be used with Off-site spacing guide.
Note: All distances in metres
N.A. Not applicable
X Provide spacing based on access for operation and maintenance.
Basic spacing is the recommended distance required between a given facility and
other general processing equipment.
See notes in section 8.1: Off-site spacing guide.
FACILITY
REF.
BASIC SPACING
BOILER HOUSES AND POWER
STATIONS
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7.0 OFFSITE SPACING
Facilities outside the confines of a Process Block, e.g. boiler houses and powerstations, administration offices, workshops, effluent treatment, flare stacks,
jetty and rail loading, blending facilities etc., are referred to as off-site
facilities.
It is customary to combine the utility type facilities, e.g. steam generation,
water treatment, plant air etc., within a utility area or block.
Effluent treatment, flare and similar high hazard off-site facilities are generally
located remote from process facilities, utility areas and administration areas.
Spacing of flare stacks requires special consideration based on relief loads andthermal radiation levels. Reference shall be made to the Process Engineer.
The recommended spacing off-site equipment is indicated in Off-site Spacing
Chart, Fig. 5.
The information on this chart is supplemented by explanatory notes contained
in Section 7.1 Off-site Spacing Guide.
It is essential that reference is made to Section 7.1 when using Off-site
Spacing Chart, Fig. 5.
Against each item a basic spacing dimension is quoted. This basic spacing is
the recommended distance in metres between the item and other
equipment/facilities. The recommended spacing between different items is
given at the intersection of the horizontal line from one item and the vertical line
from another.
In general, this shall be the greater of the basic spacing dimensions for the two
items, otherwise explanatory notes can be found in Section 7.1.
The spacing between similar equipment/facilities is given in the first box
adjacent to the item.
7.1 Off-site Spacing Guide
(Use with off-site spacing chart Fig. 5)
7.1.1 Ref. RA2 Boiler Houses and Power Stations
(Basic spacing 30 metres)
The basic spacing protects critical equipment from fire or explosion in process
equipment.
Ref. RB2 buildings are not considered hazardous to boilers and generating
plant and vice versa. Therefore, spacing less than basic for buildings is
acceptable.
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Ref. RK2 spacing protects pipe track from possible fire in boiler house.
Ref. RO2 railway main lines are not at risk from facilities and do not present arisk to facilities. Boiler basic spacing applies.
Ref. RP2 rail sidings present a minimum risk to facilities. Siding basic spacing
applies.
Note that steam generators forming an integral part of a process unit are
considered as fired heaters. In such cases, on-site basic spacing will apply.
7.1.2 Ref. RB2 Buildings, Main Office Block, Workshops, Laboratories etc.
(Basic spacing 45 metres)
The basic spacing protects personnel from fires and explosions in process
equipment.
For high hazard process equipment, spacing in excess of basic is applied.
Items Ref. RD2, RJ2, RL2 fall into this category.
Items Ref. RA2, RK2, RO2, RP2 are not considered high-risk items. Spacing
less than basic building space is applied.
7.1.3 Ref. RC2 Cooling Towers
(Basic spacing 15 metres and 30 metres)
Two basic spacing are given for Cooling Towers.
The lower basic spacing is for equipment that is lower than the cooling tower.
The higher basic spacing is for equipment that is taller than the cooling tower
and where it is necessary to minimise the corrosion, visibility and ice formation
problems, resulting from the impingement of the cooling tower exhaust plume.
A cooling tower can become a source of hazard due to release at atmosphere of
flammable vapours, caused by tube failure in water cooled exchangers. The
higher basic spacing distance is considered adequate for dispersal of these
vapours.
Spacing greater than cooling tower basic is applied from highly hazardous
sources, e.g. items Ref. RD2 and RH2.
Items Ref. RF2, RG2 and RO2 do not present a hazard to these cooling towers.
Cooling tower basic spacing is therefore applied.
Items Ref. RJ2 and RL2 are possible sources of fire. Higher cooling tower basicspacing is applied to these items.
Items Ref. RM2 and RO2 do not present a hazard to the cooling tower. Cooling
tower higher basic spacing is applied for environmental considerations.
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Item Ref. RK2 the cooling tower is not considered to be at risk from the pipe
track. Pipe track basic spacing is applied.
7.1.4 Ref. RD2 Jetties
(Loading arm manifold basic spacing 60 metres)
The basic spacing protects facilities from fires at loading manifolds or on
tankers and vice versa.
Items Ref. RN2, RP2, RQ2 are not considered as sources of hazard. Basic
spacing for these items will apply.
7.1.5 Ref. RE2 Main Electrical Sub-stations
(Basic spacing 45 metres)
The basic spacing protects electrical equipment from explosion or fire in
process areas. By using blast resistant construction, this basic spacing may be
reduced.
Items Refs. RK2, RO2, RP2 are not considered as major sources of hazard.
Spacing less than basic is allowed.
7.1.6 Ref. RF2 Fire Station
(Basic spacing 45 metres)
The basic spacing provides protection to the fire station and equipment in the
event of fire in the process areas.
Items Ref. RA2, RC2, RK2, RO2 and RP2 are not considered as major sources
of hazard. Spacing less than basic is allowed.
Items Ref. RB2, RE2, RG2 and RM2 are not hazardous to the fire station.
Location is determined by access and maintenance considerations.
7.1.7 Ref. RG2 Main Fire Pumps
(Basic spacing 45 metres)
The basic spacing provides protection to prevent loss of pumps from fire
exposure.
Items Ref. RA2, RC2, RK2, RN2, RO2 and RP2 are not considered sources of
major hazard. Spacing less than basic is allowed.
Items Ref. RB2, RE2, RF2 and RM2 are not hazardous to fire pumps. Location isdetermined by access and maintenance considerations.
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7.1.8 Ref. RH2 Fire Training Area
(Basic spacing 45 metres)
The basic spacing protects vulnerable process equipment from a source of
ignition. Spacing also allows smoke dispersal.
7.1.9 Ref. RJ2 Loading Racks
(Basic spacing 45 metres)
The basic spacing is considered adequate for the dispersal of spillage or vapour
releases. During unloading it also protects the equipment in the event of fires
at process areas and vice versa.
In locating main loading racks, consideration shall be given to access from
outside and to minimising the flow of traffic through process areas.
Spacing shall be sufficient to allow the safe manoeuvring of road tankers and
for rail sidings where applicable.
Items Ref. RC2, RK2 and RN2 are not considered hazardous with respect to the
loading area. Spacing less than loading rack basic is acceptable in these
instances.
For item Ref. RB2 spacing greater than basic is applied to reduce hazard to
personnel.
7.1.10Ref. RK2 Major Off-site Pipe Tracks
(Basic spacing 4.5 metres)
The basic spacing of 4.5 metres minimises hazard to off-site piping in the event
of fires at major plant areas.
For items Ref. RC2, RF2, RL2, RM2, RN2, RP2, RQ2 and RR2, this criterion
applies.
For items Ref. RA2, RB2, RE2, RH2, RJ2 and RO2 greater spacing is applied for
commodity criticality or personnel hazard requirement.
7.1.11Ref. RL2 Process Areas
(Basic spacing 45 metres)
The basic spacing minimises damage to other areas or equipment in the event
of fire or explosion in the process area and vice versa.
For item Ref. RB2 spacing greater than basic is applied to reduce hazard topersonnel.
Items Ref. RC2, RK2 and RN2 are not considered at high hazard from process
areas. The basic spacing for these items is therefore applied.
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A process to process area spacing of 15 metres is considered sufficient to
permit independent shutdown at turnaround.
In the case of light end units this shall be increased to 25 metres. Where
several process units are integrated, the internal spacing shall be based on
maintenance, operational and fire fighting access.
7.1.12Ref. RM2 Boundary Fence
(Basic spacing 45 metres)
The basic spacing provides protection to personnel and property outside the
boundary fence in the event of explosion or fire. It also protects the facilities
inside the fence from external hazard.
Item refs. RC2 and RK2 are reduced hazard items. Spacing less than the basic
boundary spacing is acceptable in these instances.
Item refs. RB2, RE2, RF2 and RG2 are not hazardous. Spacing from boundary
fence is based on access or environmental consideration.
7.1.13Ref. RN2 Major Pump Areas
(Basic spacing 15 metres)
The basic spacing affords protection to pump areas in the event of fire or
explosion in process facilities and allows access for fire fighting.
Pump areas, because of their low inventory, do not present a major hazard to
other equipment.
Spacing less than basic item spacing is therefore permitted from these items,
e.g. items Ref. RD2, RG2, RJ2, RL2, RO2 and RQ2.
7.1.14Ref. RO2 Railway Main Lines
(Basic spacing 60 metres)
The basic spacing protects personnel and railway property from fire or
explosion inside plant.
Items Ref. RA2, RC2, RJ2 and RN2 present a reduced hazard to railway
property. Spacing less than basic is permitted in these cases.
7.1.15Ref. RP2 Rail Sidings
(Basic spacing 15 metres)
A rail siding can be considered as a source of ignition from a locomotive engine.The basic spacing protects flammable equipment or sources of vapour emission
from this hazard.
Items Ref. RC2, RD2, RN2 and RR2 fall in this category.
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Non-hazardous items may be located at less than the basic spacing. Items Ref.
RB2, RE2, RF2, RG2 and RK2 fall in this category.
For item Ref. RQ2, additional spacing is required to permit dispersal of vapours.
7.1.16Ref. RQ2 Main Effluent Treatment
(Basic spacing 45 metres)
A basic spacing of 45 metres from process areas or other sources of ignition
allows for dispersal of vapours, which are likely to be emitted at a separator.
Items Ref. RA2 to RJ2, RL2, RM2 and RR2 fall in this category.
Lower risk facilities, not representing a source of ignition, may be located not
less than 30 metres from a separator. Items Ref. RN2 and RP2 fall in this
category.
Item Ref. RK2, off-site pipe tracks, is a minimum risk item. Its basic spacing
applies.
7.1.17 Ref. RR2 Facilities for Heat Sensitive Materials
(Basic spacing 30 metres)
Heat sensitive materials are liable to decomposition explosions on prolonged
exposure to heat. The basic spacing of 30 metres protects the facilities from
such exposure.
Items Ref. RK2 and RP2 are not sources of fire. Spacing less than basic 30
metres will be acceptable in these instances.
8.0 TANKAGE
This section gives basic guidance for the spacing and bund capacities ofstorage tanks, storage spheres and cylinders. In cases where a conflict may
occur between this document and the Thai Fuel Storage act B.E. 2474, then
that Act shall always take precedence.
For specific spacing direction, particularly for LPG and LNG duties, refer to the
relevant listed standard(s).
Other types of bulk storage, e.g. underground caverns, are not covered by this
standard.
8.1 Flammable Liquids
Petroleum products by their nature are potentially hazardous, the degree of
hazard being directly related to their volatility and flash point.
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These are classified:
Class 0 Liquified petroleum gasClass I Liquids having flash points below 21C
Class II (1) Liquids with flash points from 21C to
55C stored below flash point
Class II (2) Liquids with flash points from 21C to
55C stored at or above flash point
Class III (1) Liquids with flash points from 56C to
100C stored below flash point
Class III (2) Liquids with flash points from 56C to
100C stored at or above flash point
Unclassified Liquids which have flash points above
100C
8.2 Types of Tankage
8.2.1 The type of tank used to store a particular product is generally specified by
Clients requirements. In the absence of such requirements, type selection
should be referred to the Process Design Co-ordinator.
8.2.2 Fixed or Cone Roof Tanks (CR)
For the storage of Class III (1) and Class III (2) and Unclassified products. Other
classes of product may be stored in this type of tank, provided that the vapour
pressure at storage temperature is less than atmospheric pressure (e.g. refrig.
atmosphere storage of LPG/LNG).
8.2.3 Floating Roof Tanks (FR)
For the storage of Class II (1) and Class II (2) flammable products in the middle
flash point range.
8.2.4 Spheres and Cylinders (SP and CYL)
For the storage of Class 0 and Class I highly flammable products, which have
flash points below 21C, e.g. pressure storage of LPG products.
8.2.5 Table 1
This table gives typical examples:
Product Type of Tank or Vessel Class Comments
C3 CYL 0 Pressure Storage
C4 SP 0 Pressure Storage
C3 CR 0 Refrig. Atmos. Storage
C4 CR 0 Refrig. Atmos. Storage
LPG/LNG CR 0 Refrig. Atmos. Storage
Benzene FR I
Xylene FR I
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Product Type of Tank or Vessel Class Comments
Reformate FR I
Gasoline FR INaphtha FR I
Kerosene FR II (1)
Jet Fuel FR II (1)
Crude Oil FR II (2) Boil/roll Over
Tendencies
Gas Oil/Diesel FR III (1)
LFO CR III (2)
MFO CR III (2)
HFO CR III (2)
Heavy Oil/Residue CR III (2)
Asphalt/Bitumen CR UnclassifiedNote: Certain produce classifications may change if operational temperatures
are increased.
8. 3 Definitions
8.3.1 Bund or Firewall
A wall of pre- determined height constructed of concrete, earth, or any other
suitable material and designed to confine spillage of tank contents.
8.3.2 Bunded Area
An area bounded by bund walls to confine spillage.
8.3.3 Exposed Bunded Area
The nett effective area bounded by a bund wall after the deduction of tank
areas contained within the bunded area.
8.3.4 Secondary or Intermediate Bunds
As for bund above, but usually no higher than 600mm in order to contain local
spillage within a sub-area of the main bunded area.
8.3.5 Bund Capacity
The volume in cubic metres that can be contained within the exposed bunded
area.
8.3.6 Tank Group
A number of tanks contained within a common bund.
8.3.7 Small Tanks
A tank of 10 metres diameter or less and capacity of 8000 cubic metres of
water or less is deemed to be a small tank.
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8.4 Grouping and Spacing of Tanks
8.4.1 It is desirable to group tanks for the storage of the same products in one groupwithin a bund area, subject to the prescribed limitations of the bunded capacity.
8.4.2 It is desirable that LPG or other liquefied flammable gases should be stored
remote from other products.
8.4.3 Intermediate and component tankage should be located in areas local to their
respective units where possible so that lines can be kept to a minimum length.
8.4.4 Account should be taken of the possibility of storing more than one class of
material in certain tanks or of changing the tank service at some future date.
Where future changes of service of the storage tanks are anticipated, the layout
and spacing should be for the most stringent case.
8.4.5 Wherever possible storage tanks should not be located on high ground
overlooking the facilities. This prevents spillage of flammable liquid flowing
downhill and endangering the operating plant.
8.4.6 For fire fighting reasons there should be no more than two rows of tanks
between adjacent access roads.
8.4.7 Intermediate bunds may be provided to divide the tankage into groups of a
convenient size so as to contain small spillage and act as firebreaks.
8.4.8 For Class III (1) and Unclassified petroleum stocks spacing of tanks is governed
only by constructional and operational convenience.
Note that the spacing of Class III (1) tankage from Class I, II or III (2) tankage is
governed by the latter.
8.5 Sizing of Bunds
8.5.1 Tank bund volumes shall comply with the requirements summarised below:
110% of the capacity of the largest storage vessel located within the bund
after deducting the volume up to top of bund height of all other tanks in the
same bunded area. (HSE ref.)
8.5.2 The effective height of the bund used in calculating the capacity of the
enclosure shall be the constructed height less an amount sufficient to allow for
future consolidation, settlement and possible erosion of the fill. This freeboard
allowance shall be:
150mm for 0.6 to 1.2 m effective height
225 mm for 1.5 m effective height
300 mm for 1.8 m effective height, plus 50 mm for each 0.3 m of height over
1.8 m.
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8.5.3 Bund Walls shall generally be constructed using earth embankments having a
crest of 600-mm minimum width.
8.5.4 For bunds over 1.2 m in height, stairs shall be provided for personnel.
8.5.5 In the event that there is inadequate space for construction of earthen bund
walls due to restricted site dimensions, the use of reinforced concrete retaining
walls will be permitted.
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Example 1 Cone Roof Tanks (CR)
Tanks greater than 10 metres dia. Class II and III (2) Storage
Maximum Total Tankage Capacity of Group:
60,000m3 should not be exceeded (HSE ref)
Minimum Bund Capacity:
See Paragraph 8.5
Spacing
A to suit construction and operating conditions but not less than half tank height.
B The least of (i) half the diameter of largest tank (ii) diameter of the smaller tank. -
Shall be minimum of10 metres and need not exceed 15m
C & D See Table 2
B
D C
INSIDE TOP OF
BUND
EQUIPMENT/FACILITY REFERENCE LINE. SEE TABLE 2
AA
A A
AA
B
B
B C RC R
C R C R
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Example 2 Floating Roof Tanks (FR) Class I, II and III (2) Storage
Maximum Total Tankage Capacity of Group
120,000m3 should not be exceeded. (HSE ref.)
Minimum Bund Capacity
See Paragraph 8.5. For tanks larger than 60,000m3 not more than 2 tanks in same
compound.
Spacing
A to suit construction and operating conditions but not less than half of tank height.
B 10 metres for tanks up to and inc. 45m dia. For tanks above 45m dia., half the
diameter of largest tank or the diameter of smaller tank - but not less than15 metres
(HSE ref.)
C & D See Table 2
EQUIPMENT/FACILITY REFERENCE LINE. SEE TABLE 2
B
D C
INSIDE TOP OF
BUNDAA
A A
AA
B
B
B F RF R
F R F R
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Example 3 Cone Roof (CR) and Floating Roof (FR) in a Common Bund Class I and II
Maximum Total Tankage Capacity of Group
No of FR Tanks x 60,000 +60, 000m3
No of Tanks in group
Minimum Bund Capacity:
See Paragraph 8.5.
Spacing
A Distance equal to not less than height of tank.
B The least of (i) half the diameter of largest tank (ii) diameter of the smaller tank.
Shall be minimum of10 metres and need not exceed 15m
C & D See Table 2
EQUIPMENT/FACILITY REFERENCE LINE. SEE TABLE 2
B
D C
INSIDE TOP OF
BUNDAA
A A
AA
B
B
B F RF R
C R C R
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Example 4 Cone and Floating Roof Tanks not exceeding 10 metres diameter
Class I and II.
Fixed or floating roof tanks not exceeding 10 metres diameter may be grouped
together up to a total of 8000m3 and treated as one tank if grouped with other tanks.
Total overall tank capacity including other tanks in common bund not to exceed
60,000m3 if other tanks are fixed roof type, or 120,000m3 if other tanks are floating
roof type.
(HSE ref.)
Spacing
A to suit construction or operating requirements
B Half the diameter of larger tank but not less than 10 metres and need not be more
than 15 metres.
GROUP OF TANKS
NOT EXEEDING
8000m3 TREATED
AS ONE TANK (ref.HSE doc.)
INSIDE TOP OF
BUND
OTHER TANKAGE IN
COMMON BUND
A
A A
A
B
B
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PTT PUBLIC COMPANY LIMITED
ENGINEERING SPECIFICATION
SPC-0804.02-50.03
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Example 5 Refrigerated Storage (LPG Products at low temperatures) Fixed Roof
Tanks (CR) not more than 3 tanks in one compound.
No refrigerated LPG storage tank shall be located within a bund enclosing any other
tank. Each refrigerated storage tank shall have an individual bund unless spills can be
directed safely away from adjacent tanks and equipment by means of drainage and
diversion walls (as required) to an impounding basin located within the site boundary.
Double containment storage tanks do not require a bund except for local containment
of leakage from pipework, valves etc.
Total recommended maximum tank capacity for bund not greater than 60,000m3 .
Minimum Bund Capacity:
See Paragraph 8.5.
Spacing:
A Minimum 30 metres
B (Dia. of large tank + dia. of small tank) divided by two.
C & D See Table 2
A
BA
A
A
B B
C R C R
D C
INSIDE TOP OF
BUND
EQUIPMENT/FACILITY REFERENCE LINE. SEE TABLE2
C R
A
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ENGINEERING SPECIFICATION
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Example 6 Group of LPG pressure storage vessels (Class 0 products) Bullets and
Spheres
Notes:
1. Horizontal LPG tanks with capacities of 45 cu.m or greater shall not be formed into
groups of more than six tanks each. Horizontal vessels used to store LPG shall be
oriented so that their longitudinal axes do not point towards other containers,
process equipment, control rooms loading or unloading facilities, or flammable or
combustible liquid storage facilities located within the vacinity of the horizontal
vessel.
2. Grading of the area under and surrounding the vessels shall direct any leaks or
spills to a remote impoundment area. The remote impoundment area shall be
located at least 15 metres from the vessels draining to it and from any hydrocarbon
piping or other equipment.
Maximum number of vessels in any one group 6. Recommended maximum capacity
of all vessels within one group = 3 times capacity of largest vessel with in the
group.
Spacing:
A = sum of diameters of 2 adjacent tanks, but not less than 2 metres, for bullets.
(Reference IP LPG Vol1. Model Code of Safe Practice, Part 9)
D See Table 2
A A
d 1
D
d 2d 1
A
BL
SP
EQUIPMENT/ FACILITY REFERENCE LINES. SEE TABLE 2
D
BL BL
SP
d 1
3 m (API 2510) EDGE OF CATCHMENT
AREA
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ENGINEERING SPECIFICATION
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Example 7 Group of fixed roof refrigerated atmospheric storage tanks containing
LNG (Class O product) - Double Containment Tanks
Single Containment Tanks shall have a bunded [impounding] area. Minimum distance
from tank to bund not to be less than: height of liquid level +LP gas pressure bund
height (See NFPA 59A).
Spacing
A = Minimum distance to give a max. thermal radiation flux = 32 kW/m2 in the
event of fire (approximately equivalent to 30m).
D See Table 2
A
D
d 1 d 2
EQUIPMENT/FACILITY REFERENCE LINE. SEE TABLE2
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ENGINEERING SPECIFICATION
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Table 2 Minimum Tankage Spacing (Dimensions in Metres) (see tankage spacing
examples 1,2,3,4,5,6 &7)
Dimension C is a dimension from facility/equipment reference line to inside top of
tank bund.
Dimension D is a dimension from facility/equipment reference line to tank shell.
Examples 5,6 &7: Refer to the listed Standards for more detailed spacing requirements
regarding spillage catchment (impounding) areas and drainage. Spacing will need to be
considered for individual cases.
EXAMPLES
1,2,3,4
EXAMPLE
5 (note d)
EXAMPLE
6 (note e)
EXAMPLE
7 (note f)
FACILITY/EQUIPMENT C D C D C D C D
BOUNDARY FENCE 15 30 30 90 NA 90 NA 100
EQUIPMENT LINE PROCESS
AREA
15 30 30 50 NA 50 NA 50
BUILDINGS 15 30 30 60 NA 60 NA 60
FIXED SOURCE OF IGNITION 15 30 30 60 NA 60 NA 60
HAZARDOUS FACILITIES
(e.g. Jetty, Loading)
15 30 30 90 NA 90 NA 100
PUMP AREAS a 15 30 50 NA 50 NA 50
TANK SHELL (adjacent group) 15 30 30 50 h NA 50 NA 50 hREFRIG. FIXED ROOF TANKS 15 50 d 30 NA 30 NA 30
PRESSURE STORAGE LPG b 15 NA c 30 NA 25 NA 30
EDGE OF SITE ROADS 15 30 30 60 NA 60 NA 60
CRITICAL AREAS 15 30 30 90 NA 90 NA 100
Notes:
a To suit maintenance and operation requirements
b Assumed fitted with water deluge system.
c See notes on example 6
d, e & f: The equipment spacing listed for pressure or refrigerated storage of LPG
and the refrigerated storage of LNG, within this standard, is for initial layout purposes
(see also notes for examples 5, 6 &7). The detail design spacing will be a function of
the allowable thermal radiation flux values (permitted for fire protection) and a
hazardous assessment review. A summary of values and typical distances (in
brackets), based on a 10m height above grade from liquid product containment, is as
follows:
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ENGINEERING SPECIFICATION
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d Typical maximum thermal radiation flux values* for refrigerated storage of LPG are:
The outer surfaces of adjacent refrigerated storage vessels or surfaces thermallyprotected. =32 kW/m2 (30m)
Outer surface of adjacent storage thermally protected tanks containing
flammable products =32 kW/m2 (30m)
Unprotected metal surfaces of adjacent storage tanks, pressure vessels and
process facilities = 8 kW/m2
(50m)
Protected work area, filling/discharge points = 8 kW/m2 (50m)
Urban areas, work area = 5 kW/m2 (60m)
Critical areas = 1.5 kW/m2 (90 m)
(* Reference IP LPG Vol1. Model Code of Safe Practice, Part 9)
e. Typical maximum thermal radiation flux values for pressure stored LPG are:
The outer surfaces of adjacent pressure storage vessels or surfaces thermally
protected. =44 kW/m2 (25m)
Outer surface of adjacent storage thermally protected tanks containing flammable
products =32 kW/m2 (30m)
Unprotected metal surfaces of adjacent storage tanks, pressure vessels and
process facilities = 8 kW/m2
(50m)
Protected work area, filling/discharge points = 8 kW/m
2
(50m) Urban areas = 5 kW/m2 (60m)
Critical areas = 1.5 kW/m2 (90m)
( Reference IP LPG Vol1. Model Code of Safe Practice, Part 9)
f Typical maximum thermal radiation flux values for LNG storage are:
Concrete outer surface of adjacent storage tanks or surfaces behind thermal
protection =32 kW/m2 (30m)
Unprotected metal surfaces of adjacent storage tanks, pressure vessels and
process facilities =15 kW/m2
(45m)
Control rooms, workshops, laboratories and warehouses = 8 kW/m2 (50m)
Administration building, work area = 5 kW/m2 (60m)
Urban areas = 3 kW/m2 (66m)
Critical areas = 1.5 kW/m2 (100m)
( Reference EN 1473:1997 for LNG storage- distances based upon IP LPG Vol1.
Model Code of Safe Practice, Part 9)
h Where multiple groups are required, each group shall be separated from
unprotected adjacent groups by a minimum horizontal shell-to-shell distance of 50
metres for heights up to 10m (increase to 60m for unprotecteditems above 10m).
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REV: D2
General:
Where space is limited in tank layout areas, the use of firewalls, thermal protectionscreens, etc. may be considered.
Special spacing is required between the listed items and oxygen and/or gaseous
hydrogen storage. Refer to the relevant standard or guide.