LAYOUTS FOR OIL AND GAS INSTALLATIONS OISD – STD. 118 INDEX SECTION
1.0 2.0 3.0 4.0 5.0 5.1 5.2 6.0 6.1 6.1.1 6.1.2 6.2 7.0 7.1 7.2 8.0 8.1 8.1.1 8.1.2 8.1.3 8.2 9.0 9.1 9.2 10.0
CONTENTS
Introduction Scope Definitions Plant Layout Philosophy Layout of Blocks/Facilities General Considerations Inter-distances Layout of Process Units General Considerations Process Equipment Control Room and Sub-Station Equipment Spacing within Process Units Layout of Storage Tanks General Considerations Inter-distances between Tanks / Offsite Facilities Layout of LPG Facilities General Considerations LPG Storage LPG Bottling LPG Bulk Handling Inter-distances for LPG Facilities Layout of Utility Stations General Considerations Inter-distances References
TABLES 1. 2. 3. 4. 5. 6. 7.
Inter-distances between Blocks/Facilities Equipment Spacing within Process Units Inter-distances between Storage Tanks/Offsite Facilities (for Small Installations) Inter-distances between Storage Tanks/Offsite Facilites Inter-distances between Storage Tanks Distances from Boundary Fencing Inter-distances for LPG Facilities
8.
Inter-distances between LPG Storage Vessels and Boundary/Property Line/ Group of Buildings not associated with LPG plant.
ANNEXURE 1: TYPICAL LAYOUT OF LPG STORAGE VESSELS
LAYOUTS FOR OIL AND GAS INSTALLATIONS 1.0 INTRODUCTION Hydrocarbon processing and handling plants are inherently hazardous. Today's trend of large and complex plants presents substantial risk potential. At times plants are modified to operate at higher capacities or efficiencies necessitating larger storage requirements than contemplated earlier. For these reasons, initial site analysis for the proposed new construction or addition should be done carefully while considering the space allocation to the various facilities. The hydrocarbon industry over the years learnt lessons from fires and explosions throughout the world and has been up-dating plant safety norms including inter-distances between facilities and their relative locations. The minimum distances recommended many years ago need review in the context of today's environment in the industry. It is not intended that requirement of this standard should be applied rigidly to existing premises where for a variety of reasons, it may not be practicable to comply with. This standard will however create awareness and help in selective implementation of the recommen-dations at existing installations.
2.0
(i)
Petroleum Refinery is a plant where crude oil is received and processed into intermediates and finished products. (ii)
3.0 DEFINITIONS
OIL/GAS PRODUCTION PLANT Oil/Gas production plant is a plant where oil and/or gas is collected, stabilised and despatched for further processing. Drilling activities and facilities upstream of the christmas tree of a well are not covered under this definition.
(iii)
GAS PROCESSING PLANT Gas processing plant is a facility where natural gas is received and processed to make gas, LPG, condensate etc.
(iv)
LPG FILLING PLANT LPG filling plant is a plant where liquefied petroleum gas (LPG) is received/despatched by rail, road and pipeline and filled in cylinders.
(v)
OTHER PETROLEUM STORAGE INSTALLATIONS Other petroleum storage installations include:
SCOPE
This document lays down minimum requirements of layouts within the plant boundary for petroleum refineries, Oil/Gas production and processing plants, LPG filling plants and other petroleum storage installations. The requirement of green belt/buffer zone beyond the plant boundary is outside the scope of this standard. Such provision may be considered based on local environmental/ security requirements.
PETROLEUM REFINERY
(vi)
-
Crude oil gathering stations
-
Coastal storage installations for crude oil and petroleum products
-
Marketing depots and terminals
-
Aviation storage and fuelling stations
-
Pipeline installations/terminals.
FLASH POINT
"Flash point" of any petroleum liquid is the minimum temperature at which the liquid yields vapour in sufficient concentration to form an ignit-able mixture with air and gives a momentary flash on application of a small pilot flame under speci-fied conditions of test as per IS:1448 (Part-I). (vii) GENERAL CLASSIFICATION PETROLEUM PRODUCTS
OF
(ix)
It is an additional railway line/spur reserved for additional rake/stabling.
4.0 PLANT LAYOUT PHILOSOPHY A petroleum installation may be broadly considered as a group of one or more of the following units/facilities:
Petroleum products are classified according to their closed cup FLASH POINTS as follows: —
—
—
—
Class "A" Petroleum: Liquids which have flash point below 23 o C. Class "B" Petroleum: Liquids which have flash point of 23 oC and above but below 65 oC. Class "C" Petroleum: Liquids which have flash point of 65 oC and above but below 93 oC. Excluded Petroleum: Liquids which have flash point of 93 oC and above.
(a)
(b)
-
Intermediate and finished product storage
-
LPG storage and handling facilities
-
Process units and control room
-
Product loading/unloading facilities (Rail, Road and Pipelines)
-
Utilities generation and distribution centres
-
Blowdown and flare system
-
Waste water treatment facilities
-
Administrative and service buildings (ware-house, workshop, canteen, fire station, laboratory, first aid, parking lot etc.)
(i)
BASIC INFORMATION (a)
Information on following items should be collected before proceeding with the development of overall plot plan: Process units and their capacities
-
Where product handled is artificially heated to a temperature above its flash point.
Process flow sequence
-
Utility requirements
-
Storage tanks list
-
LPG storage vessels and their sizes
-
Product despatch and mode of transport (rail, road and pipeline)
-
Warehouses, open storage areas
-
Number of flares
Tank height is the:
-
Crude oil storage
Where ambient temperatures or the handling temperatures are higher than the flash point of the product.
(viii) TANK HEIGHT
-
-
Following points shall be kept in mind while developing overall plant layout of any installation.
Liquefied gases including LPG, do not fall under this classification but form separate category. In the following cases, above classification does not apply and special precautions should be taken as required:
STABLING LINE
Height from tank bottom to top kerb angle for cone roof tanks Height from tank bottom to top of tank shell for floating roof tanks
diagram
indicating
flow
(ii)
-
Operating and maintenance philosophy for grouping of utilities
-
Plant and non-plant buildings
-
Environmental considerations
-
Scrap yards and dumping ground
-
Fire station and fire training ground
-
Chemical/Toxic Chemical storage
-
Storage areas for solid products such as petroleum coke, petroleum wax, coal, bitumen and asphalt
(b)
Data on following infrastructural facilities should be collected before detailed layout activity is taken up and due consideration should be given for the same while deciding plant layout:
-
Site location map
-
Prevailing wind direction
-
Area topography contour map
-
High flood level in the area
-
Source of water supply and likely entry point
-
Electric supply source and direction of entry point
-
Crude oil entry point
-
Storm water disposal point and effluent disposal point
-
Railway entry point and marshalling yard location
-
Approach roads to main plant areas
-
Inward/outward product movement by rail/ road and pipelines.
Surrounding risks BLOCKS (a)
(b)
In any process installation, it is recommended that plant layout arrangement should follow the general route of raw material to process unit (s) with tankages interposed as required followed by despatch facilities. Block layout should be adopted as much as possible. The entire area should be sub-
divided into blocks. Maximum size of a block should be established based on tank farm layouts. (iii)
(iv)
ROADS (a)
All process units and dyked enclosures of storage tanks shall be planned in separate blocks with roads all around for access and safety. Primary traffic roads in the installation should be clear of hazardous classified areas. Roads separating the blocks shall provide fire breaks and have facilities for fire fighting activities.
(b)
Alternative access should be provided for each facility so that it can be approached for fire fighting/maintenance/construction in the event of blockage on one route.
(c)
Road widths and turning radii at road junctions shall be designed to facilitate movement of the largest fire fighting vehicle in the event of emergency.
(d)
Rail spur shall be located close to the periphery of the plant to minimise road crossings and blockage of roads during shunting.
(e)
Layout of the facilities shall be made to minimise truck traffic ingress in the plant.
(f)
Two road approaches from the highway should be provided, one for employees and other for product movement. Both these approaches should be available for receipt of assistance in emergency. However, for smaller installations, this requirement may be relaxed if not feasible.
LOCATION (a)
Process unit(s) should be located on high ground to avoid flooding.
(b)
Presence of ignition source shall always be contemplated beyond the boundary wall of the installation.
(c)
Orientation of flares,furnaces/heaters, dusty operations (e.g. sulphur handling) and cooling towers should be decided based on prevailing wind direction.
(V)
(vi)
ERECTION AND MAINTENANCE (a)
Erection methods shall be anticipated for all types of equipments. Towers, reactors and fired equipments should be located away from congested areas to facilitate erection at any stage.
(b)
Maintenance methods for each type of equipment shall be identified in advance since these affect the requirements for layout. Equipment requiring frequent attention shall have easy accessibility. For equipments having removable parts, wherever possible, arrangements shall be made to facilitate their removal without dismantling long lengths of piping. Free access shall be provided for hoisting the equipment.
FUTURE EXPANSION
(iii)
Location of tall columns and furnaces should be close to road side for ease of construction and maintenance. (iv)
Storage tanks should be grouped according to product classification. In undulating areas, storage tanks should be located at lower elevations.
(v)
Utility blocks should be located adjacent to unit blocks.
(vi)
Main power receiving station should be close to the fence line with minimum overhead power transmission lines passing through the installation.
Future expansion shall be assessed and space provision for known and unforeseen needs shall be made. Orderly future expansion shall be affected by providing space adjacent to similar type of facilities for expansion. Extension of pipe sleepers and pipe way, road crossings for yard piping shall be given due consideration. Care shall be taken to facilitate future expansion without any interferene to plant on-stream.
Overhead power transmission lines shall not pass over process units, storage tanks, offsite and utility areas. Wherever these lines are passing through plant premises adequate safety distances shall be kept. (vii)
5.0. LAYOUT OF BLOCKS/FACILITIES An installation may consist of one or more of the following basic blocks/facilities: -
Storage tanks/offsites
-
LPG storage and filling facilities
-
Process units
-
Utilities and effluent disposal facilities
(ix)
Gas/Oil based power plants should be located close to process units/utility blocks and closer to Main Receiving Station, as far as possible. Coal based power plants should be located away from criticalfacilities like air separation plants, electrical installations etc. to avoid problems due to coal dust and ash.
(x)
Flare should be located upwind of process units. Height of flare and its distance from operating facilities shall be decided based on heat radiation considerations and other considerations like ground level concentration, cold venting etc.
While locating the above blocks/facilities and further sub blocks/facilities within them, following items should be considered : Layout planning should be in sequential order of process flow.
(ii)
Orientation should be to suit wind direction to avoid travel of hydrocarbon vapour over sources of ignition.
H T sub-station should be located close to major load centres. One or more sub-stations could be provided to limit distances.
(viii) L T sub-station should generally be located at load centres in such a way that the distance between distribution transformer and farthest motor is minimum.
5.1 GENERAL CONSIDERATIONS
(i)
Process units should be centrally located with straight approach from main gate. Orientation of process units should follow process flow in sequential order so that piping runs are also minimum.
5.2 Area around flare should be paved to avoid growth of grass/vegetation which can otherwise provide combustible material for fires. (Ref. section 8.0 of OISD-STD-106 on "Process Design and Operating Philosophies on Relief and Disposal systems"). (xi)
Truck loading facilities should be located close to product movement gate. Rail loading facilities should suit rail siding layout and preferably be located along periphery of the installation.
(xii)
Effluent Treatment Plants should be located minimum one block away from unit area, down wind of process units and important areas to avoid odour problems. They should be closer to disposal point and at lower grade to facilitate gravity flow of effluent.
(xiii) Sulphur recovery unit and sulphur loading area should be located close to product movement gate and away from hazardous and populated areas. A minimum distance of 50m is recommended between sulphur storage/handling and any building or boundary wall. (xiv) Petroleum coke/coal storage and handling facilities should be located as far as possible away from process units, air separation plants, populated and hazardous areas. (xv)
Sufficient open areas should be left where construction activities can be undertaken. Requirements for erecting tall structures should be studied before finalising the layout.
(xvi) Fire station should be located close to main entry gate with straight approach to process units/other critical areas. Fire station and fire water pump house shall be located at a safe place away from hazardous areas. Fire station includes fire tenders, foam equipments and fire fighting accessories. (xvii) Fire water storage and pumps shall be located at a minimum distance of 60 m from hydrocarbon storage and process units. However for petroleum depots and terminals, it shall be as per clause 4.3.5(V) of OISD-STD-117.
INTERDISTANCES
Interdistances between various blocks/facilities described above shall be as per Table-1.
OISD-STD-118 Revision - II
9
TABLE - 1 (NOTE1) MINIMUM INTERDISTANCES BETWEEN BLOCKS/FACILITIES S.No. From \ To
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15 16
1.
Process Units
36
***
30
45
30
60
90
150
45
60
45
30
60
60
30
90
2.
Process Control Room
***
-
**
45
30
60
90
150
45
30
30
-
30
15
30
30
3.
Storage Tank Class A
30
**
T3 & T5
T3 & T5
T3 & T5
30
90
150
30
60
90
30
T6
60
30
50
4.
Storage Tank Class B
45
45
T3 & T5
T3 & T5
T3 & T5
30
90
150
30
60
90
30
T6
30
30
50
5.
Storage Tank Class C
30
30
T3 & T5
T3 & T5
T3 & T5
30
90
150
30
60
90
30
T6
30
30
50
6.
Storage Vessels 60 (Pressure) LPG/Other
60
30
30
30
T7
90
150
30
90
90
30
T8
45
30
60
7.
Flares-elevated
90
90
90
90
90
90
90
150
90
90
90
90
90
90
90
90
8.
Flares-ground
150
150
150
150
150
150
150
150
150
150
150
150
150
150
150
150
9.
Bulk loading racks (rail/road) LPG/POL
45
45
30
30
30
30
90
150
60
30
60
60
60
90
90
150 90/60
10. Fire stations/ First aid centre
T7 90/60 30 -
T7 T6/T760 30
30
12
30 12
30
50 90 Contd...
10
TABLE - 1 (Contd..) S.No. From \ To
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15 16
11. Boiler House/ heaters
45
30
90
90
90
90
90
150
30
30
-
15
50
30
30
90
12. Rail spur
30
-
30
30
30
30
90
150
T7
30
15
-
30
6
15
50
13. Boundary fence around installation
60
30
T6
T6
T6
T8
90
150 T6/T7 12 50 30
-
6
30
50
14. Service buildings
60
15
60
30
30
45
90
150
60
12
30
6
6
-
30
50
15. Cooling towers, water storage, nitrogen plant
30
30
30
30
30
30
90
150
30
30
30
15
30
30
-
15
16. API Separators/ oil sludge pit
90
30
50
50
50
60
90
150
50
90
90
50
50
50
15
-
**
Distance will be 30 meters in case Control Room is blast proof and 60 meters in case it is not blast proof.
***
Refer OISD-STD-163 on Process Control Room Safety
Notes : 1.
All distances are in metres.
2.
All distances shall be measured between the nearest points on the perimeter of each facility except in case of tank vehicle loading/unloading area where the distance shall be measured from the centre of each bay.
3.
"T" indicates the table to be referred.
4.
Where distances have not been specified, it shall be decided based on construction,operation & maintenance requirements.
5.
API/CPI, open oil separators/oil collection sumps shall be categorised under the same risk and shall be located at 90m distance from heaters/boilers. However, if these are covered from top and provided with adequate venting to safe location, the minimum safe distance can be reduced from 90m to 30m.
OISD-STD-118 Revision - II 6.
7.
11
Distance between bulk loading racks and fire station shall be : (i)
For LPG Gantry - 90 m &
ii)
For POL Gantry - 60 m.
Definitions : Process Unit - a unit having integrated sequence of operation , physical and chemical, and may involve preparation, separation, purification, or change in state, energy content or composition. Service building – a building housing facilities for inspection/maintenance/other supporting services which are directly required for operation of the plant. Fire station – a building housing facilities of parking fire tenders and keeping other ready to use fire fighting equipment for meeting plant emergencies, fire control room with required communication facilities/mimic panel. Fire pump house – a building housing main fire water pumps, jockey pumps, communication and alarm system, instrumentation and the required operating & supporting personnel.
12
OISD-STD-118 Revision - II -118 Revision - I
6.0
LAYOUT OF PROCESS UNITS
6.1
GENERAL CONSIDERATIONS
6.1.1 PROCESS EQUIPMENT (i)
Process flow sequence and operating procedures shall be thoroughly understood so that equipment arrangement in the plot plan is functional. Equipment shall be arranged in logistic process sequence for short piping runs and operational ease.
(ii)
It is recommended that the unit pipe rack be kept in the centre, thereby splitting the unit into two or more areas of equipments.Pumps may be arranged in two rows close to and on either side of the central pipe rack. Heat Exchangers and vessels should be grouped together forming outer rows on both sides of the rack. Fired heaters should be kept at open end of the unit upwind from the remaining plant equipments.
(iii)
Spacing between battery limits of individual pieces of equipment shall be adequate for undertaking maintenance jobs.
(iv)
Spacing between two process units in a complex should be decided based on shut down philosophy for maintenance of the units. If the shut down of the units are expected at different occasions, then inter distances may be increased.This will facilitate ease in maintenance and minimise risk from/for operating units due to hot jobs in the units under shut down.
(v)
(vi)
Heat exchangers should be located perpendicular to the pipe rack on the outer row to facilitate pulling of tube bundles with mobile crane or by other means. Shell and tube heat exchanger should have a longitudinal clearance of at least one metre plus the length of removable bundles. Air fin coolers should be installed above the pipe rack. Pumps handling hydrocarbons and materials above the temperature of 230 degree C should not be installed underneath the air fin coolers.
(vii) Cold boxes should be located on grade or on separate elevated structures. Adequate space should be provided around cold boxes for ease of operation and maintenance. (viii) Vessels having large liquid hold-up should be installed at lower heights and preferably at grade. Adequate drainage should be provided around such vessels. Where process requirement dictates their installation above grade, these should be located in open area. (ix)
Towers/columns should be located along the pipe rack towards open areas for unobstructed erection as well as maintenance of internals at grade. Tall towers require frequent operating attention at upper levels. Hence they may be located at one place so that common connecting platform can be provided.
(x)
Thermo-siphon reboilers should preferably be placed close to their associated towers. Reboiler should be mounted on the tower so that vertical expansion will be uniform, piping system design is simplified and inlet/outlet piping is minimised. Clearance shall be provided for movement between reboiler and tower.
(xi)
Gas compressors should be located down wind from heaters so that leaked gases will not drift towards the heater. Gas compressors should have roofing and open from sides to avoid accumulation of heavier vapours/gases on the floor of compressor house. Compressor house should be located near the battery limits to facilitate ease in maintenance and operation.
(xii)
Heaters should be located up wind at one corner of the unit. Space should be provided for removal and cleaning of heater tubes besides approach for crane. Areas around the heaters shall be graded for guiding spills away from process equipment. FD fans shall be located away from process equipment from where they arelikely to suck hydrocarbon vapours. The local control panel for soot blower control and flue gas analyser shall only be
OISD-STD-118 Revision - II
13
located on and near the process heater. The rest of controls shall be taken to central control room.
protection to instruments and personnel is ensured and non-hazardous electrical area classification is permitted. It should have alternate means of exit with doors opening towards outside. Doors should be made of fire proof material.
(xiii) No other tankage except day tanks shall be provided within battery limits of any process unit. (xiv) Flare knock out drum of the closed blow down system should be located at battery limit of the unit. (xv)
Control room should be designed to cater for minimum occupancy.
(iii)
Transformers should be located in open area on the rear side of sub-station.Each transformer shall be isolated from the other by a brick masonary wall. Approach road to sub-station and transformer bays should be provided to facilitate crane movement for erection and maintenance.
(iv)
Electrical sub-station should be located adjacent to the control room building and should meet the requirements of electrical area classification.
Blow down facilities/burried drum shall be located at one corner of the plant farthest from furnace or any fired equipment and on the lee-ward side of the unit. Vent from Blow down facility shall be minimum 6m clear off the air fin coolers. It shall be minimum 6m above the highest platform if horizontal distance of 15m from process equipment is not possible.
6.1.2 CONTROL ROOM AND SUB-STATION (i)
(ii)
Control room should be located distinctly in the process block or in the adjoining block. It should be at a safe distance where
6.2
EQUIPMENT SPACING WITHIN PROCESS UNITS Interdistances betweenvarious equipments in process units shall be as per Table-2.
14
OISD-STD-118 Revision - II
TABLE-2 MINIMUM INTERDISTANCES BETWEEN EQUIPMENTS WITHIN PROCESS UNIT “This table could be used by the oil companies as a guideline for their projects. These could be suitably modified as required to suit space constraints and relevant engineering practices.” NOTE 1
S.No.
From \ To
1
2
3
4
5
6
7
8
9
10
11
1.
Fired heaters/ any fired equip.
-
15
15
15
22.5
15
15
20
15
15
15 16/30
2.
Reactors
15
2
2
6
8
7
15
7
7
4
3
3.
Distillation columns
15
2
3
4
7.5
5
15
5
5
2
4.
Accumulators (Hydrocarbon)
15
6
4
2
8
5
15
4
4
5.
Gas compressors (Hydrocarbon)
22.5
8
7.5
8
3
7.5
15
7.5
6.
Hot oil transfer pumps
15
7
5
5
7.5
1
7.5 1
7.
Fuel Oil Day tank
15
15
15
15
15
7.5
8.
Pump for Class A & 20 all products above auto-ignition temp.
7
5
4
7.5
9.
Pumps - other Hydrocarbon
15
7
5
4
10. Heat ExchangerHydrocarbon
15
4
2
11. Air Fin CoolersHydrocarbon
15
3
12. Control room 13. Snuffing/purging steam isolation valve
16/30 15
12
13
14
15
16
17
18
19 20
15
-
18
15
6
30
15
15
16
-
15
5
15
3
15
15
3
3
20
-
15
3
15
3
15
15
3
2
3
20
-
15
3
15
3
15
15
3
7.5
7.5
7.5
16
-
15
4
15
3
20
15
7.5
1
1
2
2
16
-
15
3
15
-
15
15-
2
15
15
15
15
16
-
15
15
15
-
15
15
1
15
1
1
2
2
16
-
15
3
15
-
15
15
7.5
1
15
1
1
2
2
16
-
15
3
15
-
15
15
-
2
7.5
2
15
2
2
2
2
16
-
15
2
15
2
15
15
-
3
3
7.5
2
15
2
2
2
-
16
-
15
2
15
-
15
15
16
20
20
16
16
16
16
16
16
16
-
16
20
16
-
16
16
5
16
-
-
-
-
-
-
-
-
-
-
16
-
-
2
-
-
15
5
-
15 -
2
OISD-STD-118 Revision - II 14. Fired heaters control panel (local)
15 -
15
15
15
15
15
15
15
15
15
15
20
-
-
10
15
-
15
15
5
Contd....
TABLE - 2 (Contd...) S.No.
From \ To
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19 20
18
5
3
3
4
3
15
3
3
2
2
16
2
10
2
15
3
15
15
16. Fire water 15 hydrants/monitors
15
15
15
15
15
15
15
15
15
15
-
-
15
15
-
15
15
-
-
6
3
3
3
3
-
-
-
-
2
-
16
-
-
3
15
-
15
15
-
18. Blow down facility (pumps, drums, stacks)
30
15
15
15
20
15
15
15
15
15
15
16
15
15
15
15
15
-
15
15
19. Water spray Deluge valve
15
15
15
15
15
15
15
15
15
15
15
5
5
15
15
-
15
15
-
-
20. Structural main (Technological platforms)
15
3
3
3
7.5
-
15
-
-
-
2
16
-
5
2
-
-
15
-
-
15. Pressure Vessel/ Drums (Hydrocarbon)
17. Pipe rack (main)
2
Notes: 1. 2. 3. 4. 5.
6. 7. 8.
All distances are face to face clear minimum distances in meters. Distance between equipments not covered herein & equipments handling non-hydrocarbons shall be as per good engineering practices. From control room to heater, safe distance shall be 16m if the control room is for one unit and shall be 30m, if it is for two units. For gas processing plants, it shall be 30m irrespective of whether the control room is for one or more units. Distances between the reactor and furnace when directly connected process-wise, can be relaxed to 5m. Only distances indicated from fired heaters (1) Fuel oil day tank (7), Control room (12), Fired heater local control panel (14), Fire water hydrant/monitor (16), Blow down facility (18) and water spray deluge valve (19) are by safety considerations. Other distances indicated are recommended from erection, operation and maintenance safe guards. The local control panel meant for soot blower control & fuel gas analyser shall only be located on and near the process firedheater. The rest of controls shall be taken to central control room. Safety distances as per preceeding Table-2 for blow down facilities are for open pit location. If the blow down drum is located underground, the distance from fired heater shall be reduced from 30m to 15m. Steam snuffing/purging valve shall be located minimum 15m from only those equipments which are served bythe steam valve.
16 9. 10. 11.
OISD-STD-118 Revision - II Fuel Oil day tanks shall be located at a safe distance of 15m from equipment except those facilities such as heat exchanger, pump connected directly with the Fuel Oil system. (Refer Table-5 for interdistance between tanks). Distance between fired heater and distillation column shall be increased to 22.5m in case of light ends such as Naphtha stabiliser. Minimum distances between equipment shall not be applicable for package items and their related appertenances.
OISD-STD-118 Revision - II
17
7.0
LAYOUT OF STORAGE TANKS
7.1
GENERAL CONSIDERATIONS
(i)
DYKED ENCLOSURES (a)
either buried underground or installed in the open and surrounded by wall or embankment not more than two meter high and made of earth, concrete or solid masonry capable of withstanding fully hydrostatic load. Earth wall of over 1 meter high shall have not less than 0.6 meter wide flat section on top. Note 2
Petroleum storage tanks shall be located in dyked enclosures with roads all around the enclosure. Aggregate capacity of tanks located in one dyked enclosure shall not exceed following values : For a group of floating roof tanks
: 120,000 cu.m.
(f)
Pump stations should be located outside dyke areas by the side of roads.
(g)
Tanks located overhead for process considerations shall meet safety distance and shall also have dyked enclosure of RCC construction and provided with drain valves at suitable height for easy operation.
For a group of fixed roof tanks : 60,000 cu.m. If a group of tanks contains both fixed and floating roof tanks, thenit shall be treated as a group of fixed roof tanks for the purpose of above limits. (b)
(c)
(ii) GROUPING (a)
Dyked enclosure should be able to contain the complete contents of the largest tank in the tank farm in case of any emergency. Enclosure capacity shall be calculated after deducting the volume of tanks (other than the largest tank) upto the height of the enclosure. A free board of 200 mm above the calculated liquid level shall be considered for fixing the height of the dyke.
Grouping of petoleum products for storage shall be based on the product classification. Class "A" and/or class "B" petroleum can be stored in the same dyked enclosure. Class "C" petroleum should preferably be stored in separate enclosure. However, where class "C" petroleum is stored in a common dyke along with class "A" and/or class "B" petroleum, all safety stipulations applicable for class "A" and/ or class "B" respectively shall apply.
(b)
However, for excluded petroleum, the capacity of the dyked enclosure should be based on spill containment but not for containment on tank rupture.
Excluded petroleum shall be stored in a separate dyked enclosure and shall not be stored along with class A, B or C petroleum.
(c)
Tanks shall be arranged in maximum two rows so that each tank is approachable from the road surrounding the enclosure. However, tanks having 50,000 cu.m capacity and above shall be laid in single row.
The height of tank enclosure dyke shall be at least one metre and shall not be more than 2.0 m above average grade level inside. However, for excluded Petroleum, the minimum height of dyke wall shall be 600 mm.
(d)
Interdistance between the nearest tanks located in two dykes shall be equivalent to the largest tank diameter or 30m, whichever is more.
(e)
The tank or tanks shall be supported on well designed foundations and shall be
(iii)
FIRE WALLS In a dyked enclosure where more than one tank is located, fire walls of 600mm should be provided as explained below: (a)
Any tank having a diameter more than 30m should be separated with fire walls from other tank.
18
OISD-STD-118 Revision - II
(b)
(iv)
7.2
Fire walls should be provided by limiting the aggregate capacity of each group of tanks within, to 20,000 cu.m.
The following stipulations shall apply for the inter distances for above ground tanks storing petroleum: (i)
Inter distances shall be as given in Table-3 for tanks storing class "C" petroleum; or class "A" and "B" petroleum products with total storage capacity not exceeding 5000 cu.m at one installation.
(ii)
Inter distances shall be as given in Table-4 for tanks storing class "A" and class "B" petroleum products with total storage capacity exceeding 5000 cu.m
(iii)
Interdistances between tanks and fencing shall be as given in Table-6 for tanks storing Class "A", Class "B" and Class "C" petroleum products with total storage capacity of class "A" and class "B" petroleum stored exceeding 5000 cu.m
(iv)
Interdistances between tanks storing excluded petroleum will not be governed by Table-3 and 4 and should be decided on construction, operation and maintenance requirements.
GENERAL (a)
The tank height shall not exceed one and half times the diameter of the tank or 20m whichever is less.
(b)
Piping from/to any tank located in a single dyked enclosure should not pass through any other dyked enclosure. Piping connected to tanks should run directly to outside of dyke to the extent possible to minimise piping within the enclosures.
(c)
No fire water/foam ring main shall pass through dyked enclosure.
(d)
The minimum distance between a tank shell and the inside toe of the dyke wall shall not be less than one half the height of the tank.
INTERDISTANCES BETWEEN TANKS / OFFSITE FACILITIES
OISD-STD-118 Revision - II
19
TABLE - 3 (NOTE1) INTERDISTANCES BETWEEN TANKS/OFFSITE FACILITIES (For small installations) S.No.
From \ To
1
2
3
4
5
6
7
8
9
10
11
12 15
13
1.
Storage tank for petroleum class A
0.5 D
0.5 D or 6
0.5 D or 6
9
9
9
15
15
15
3
15
2.
Storage tank for petroleum class B
0.5 D or 6
0.5 D
0.5 D or 6
9
0.5 D
0.5 D
9
4.5
4.5
3
4.5
3.
Storage tank for petroleum class C
0.5 D or 6
0.5 D or 6
-
9
0.5 D
-
9
4.5
-
-
-
0.5 D min.3
0.5 D min.3
4.
Storage / filling shed for petroleum class A
9
9
9
-
4.5
6
9
9
9
3
9
9
9
5.
Storage / filling shed for petroleum class B
9
0.5 D
0.5 D
4.5
-
1.5
9
4.5
4.5
1.5
4.5
4.5
4.5
6.
Storage / filling shed for petroleum class C
9
0.5 D
-
6
1.5
-
9
4.5
-
-
-
3 3
7.
Tank vehicle loading / unloading area for petroleum class A
15
9
9
9
9
9
-
9
9
3
9
9
9
8.
Tank vehicle loading/ unloading area for petroleum class B
15
4.5
4.5
9
4.5
4.5
9
-
4.5
1.5
4.5
4.5
4.5
9.
Tank vehicle loading/ unloading area for petroleum class C
15
4.5
-
9
4.5
-
9
4.5
-
-
-
3 3
3
3
-
3
1.5
-
3
1.5
-
-
3
-
10. Flame-proof electric motors
15
D D min.4.5 min.4.5
Contd...
20
OISD-STD-118 Revision - II
TABLE - 3 (Contd...) S.No.
From \ To
1
2
3
4
5
6
7
8
9
10
11
12
13
11. Non-flameproof electric motors
15
4.5
-
9
4.5
-
9
4.5
-
3
-
-
-
12. Office building, stores, amenities etc. within installation
15
D min. 4.5
0.5 D min. 3
9
4.5
3
9
4.5
3
-
-
-
-
13. Boundary fencing around installation
15
D min. 4.5
0.5 D min. 3
9
4.5
3
9
4.5
3
-
-
-
-
Notes: 1.
All distances are in metres.
2.
Above table is applicable for installations where i) Only petroleum class C is stored. ii) The total quantity of petroleum class A and class B stored above ground in bulk does not exceed 5000 cu.m. iii) The diameter of any tank storing petroleum class A or petroleum class B does not exceed 9m.
3.
Interdistances given for tanks are shell to shell in the same dyke.
4.
All distances shall be measured between the nearest point on the perimeter of each facility except in the case of tank vehicle loading/unloading area where the distance shall be measured from the centre of each bay.
5.
Where alternate distances are stipulated, maximum thereof shall be observed.
6.
Notation : "D"
– diameter of the tank
(-)
– a distance suitable for constructional and operational convenience.
OISD-STD-118 Revision - II
21
TABLE - 4 INTERDISTANCES BETWEEN STORAGE TANKS/OFFSITE FACILITIES S.No.
From \ To
1
2
3
4
5
6
7
8
9
1.
Storage tank for petroleum class A
T5
T5
T5
15
15
15
15
8
15
2.
Storage tank for petroleum class B
T5
T5
T5
15
15
15
15
8
15
3.
Storage tank for petroleum class C
T5
T5
T5
15
-
8
-
-
-
4.
Storage / filling shed for petroleum class A or class B
15
15
15
-
8
15
15
8
15
5.
Storage/filling shed for petroleum class C
15
15
-
8
-
8
-
-
-
6.
Tank vehicle loading/ unloading area for petroleum class A or B
15
15
8
15
8
-
-
8
15
7.
Tank vehicle loading/ unloading area for petroleum class C
15
15
-
15
-
-
-
-
-
8.
Flame proof electric pump motor
8
8
-
8
-
8
-
-
8
9.
Non-flame proof electric pump motor
15
15
-
15
-
15
-
8
-
Notes : 1.
All distances are in metres.
2.
Above table is applicable for installations where total quantity of petroleum class A and class B stored above ground in bulk exceeds 5000 cu.m or where the diameter of any such tank for the storage of petroleum exceeds 9 m.
3.
All distances shall be measured between the nearest points on the perimeter of each facility except in the case of tank vehicle loading/unloading area where the distance shall be measured from the centre of each bay.
4.
Notation:
5.
(-)
– any distance suitable for constructional or operational convenience.
T5
– Table-5 shall be referred.
This table is applicable for class C petroleum storage also alongwith class A & B petroleum as per limits specified under note-2 above.
OISD-STD-118 Revision - II
23
TABLE - 5 INTERDISTANCES BETWEEN STORAGE TANKS
Sl. No.
Item
Floating Roof Tanks
Fixed Roof Tanks (Class A & B Petroleum
Class C Petroleum
1.
All tanks with diameters upto 50 metres
(D + D) / 4
(D + d) / 4
(D + d) / 6
2.
All tanks with diameters exceeding 50 metres
(D + d) / 4
(D + d) / 3
(D + d) / 4
Notes : 1.
This table is applicable for installations where aggregate storage capacity of class A and class B petroleum stored above grade exceeds 5000 cu.m. or where the diameter of any such tank for the storage of petroleum exceeds 9 m.
2.
Distances given are shell to shell in the same dyke.
3.
Notation: D
– diameter of larger tank in metres
d
– diameter of smaller tank in metres
4.
If the interdistance (for class A & B) calculated as above are less than 15m,then minimum of 15m or 0.5 D or d shall be followed.
5.
Interdistance between class A/B storage tanks and classC storage tanks shall not be less than 6 metres.
TABLE - 6 (NOTE1) DISTANCES FROM BOUNDARY FENCING
S.No.
Installation
Minimum Distance from Boundary fencing around Installation
1.
Storage tank for Petroleum Class A
**
2.
Storage tank for Petroleum Class B
**
3.
Storage tank for Petroleum Class C
**
4.
Storage/filling shed for Petroleum Class A or Class B
15
5.
Storage/filling shed for Petroleum Class C
10
6.
Tank vehicle loading/unloading area for class A & B petroleum
20
7.
Tank vehicle loading/unloading area for class C petroleum
10
Notes : 1.
All distances are in metres.
2.
This table is applicable for facilities in an installation where total quantity of petroleum class A & B stored above ground in bulk exceeds 5000 cu.m. or where the diameter of any such tank for the storage of petroleum exceeds 9 m.
3.
Notation: "D" – diameter of larger tank in metres.
4.
**
Above table is based on the assumption that property beyond the boundary line is either protected or adequate green belt is provided as a safety buffer where no structure exists. Property beyond property line is deemed protected if it is within the jurisdiction of public Fire Brigade or plant's own Fire Brigade.
(I) Distance from Floating roof tank to boundary fencing for stable and boil-over liquids, having protection for exposure shall be D/2 (minimum 20m). (ii)
For tanks with weak roof-to-shell joint :
OISD-STD-118 Revision - II The above distance shall be D/2 (minimum 20m) for tanks having approved foam or inerting system and the tank diameter not exceeding 50m.
25
8.0
LAYOUT OF LPG FACILITIES
8.1
GENERAL CONSIDERATIONS
(b)
8.1.1 LPG STORAGE (i)
GROUPING Vessels shall be arranged into groups each having a maximum of six vessels. Capacity of each group shall be limited to 15000 cu.m. Each group shall be provided with a curb wall.
(c)
There shall not be any depressions, large ditches and low lying areas around LPG storage as the leaked gas can accumulate, being heavier than air. Top surface of the vessels installed in a group should be on the same plane so that safety blowout from one vessel does not affect the other vessel. This will also minimise the chances of overfilling of adjoining vessels due to gravitation.
(d)
A typical layout plan of LPG sphere area with major safety requirements of distances, drainage sump, pump station location etc. is enclosed at Annexure-1 for general guidance.
Any vessel in one group shall be separated from a vessel in another group by a minimum distance of 30m. Spheres and bullets shall be treated as separate groups with 30m safety distance between two groups. Separate dedicated manifold shall be provided for each group. ii)
LOCATION (a)
(iii)
Longitudinal axes of horizontal vessels (Bullets) should not point towards other vessels, vital process equipments and control room.
of one sphere, the sump size shall be equal to layout of two spheres. Curb wall around the storage tank shall have a minimum height of 30cm. However it shall not exceed 60cm at shallow sump position, as otherwise evaporation of spilled LPG may get affected.
8.1.2 LPG BOTTLING (i)
LOCATION
(b)
Storage vessels should be located down wind of process units, important buildings and facilities.
LPG bottling facilities should be located at a safe distance from other facilities with minimum ingress to trucking traffic and downwind to storage as far as possible.
(c)
LPG storage vessels shall not be located within the same dykes where other flammable liquid hydrocarbons are stored.
There shall not be any deep ditches in the surrounding area to avoid LPG settling.
(d)
Storage vessels shall be laid out in single row both in case of the spheres and bullets. Storage vessels shall not be stacked one above the other.
(ii)
Bottling section shall be of single storey having roofing and open from sides for adequate ventilation so that leaked gas can drift away. RCC roofing should not be used to the extent possible.
SPILLS AND LEAKS (a)
Spillage collection shallow sump shall be located at a distance where the flames from sump fire will not impinge on the vessel. This distance shall not be less than the diameter of the nearest vessel or 15m whichever is higher. The capacity of the collection sump shall be as per drawing enclosed at Annexure-1. However in case
CONSTRUCTION
(iii)
OPERATION (a)
Stacking areas for empty and filled cylinders should be located separately. Cylinders shall be stacked vertically. Filling machines and testing facilities shall be organised in sequential manner distinctly in a separate area.
OISD-STD-118 Revision - II (b) (c)
(d)
Filled LPG cylinders shall not be stored in the vicinity of cylinders containing other gases or hazardous substances. Storage shall be kept on or above grade and never below grade in cellar or basement. Trucking traffic shall be smooth to avoid blocking/ obstruction for loading and unloading of cylinders.
8.1.3 LPG BULK HANDLING (i)
LOCATION (a)
27
LPG truck loading/unloading station shall be located in a separate block and shall not be grouped with other products. Maximum number of LPG tank lorry bays shall be restricted to 8 in one group. The bay should be designed in such a way that the driver's cabin will be facing the exit direction and shall have no obstruction.
(ii)
(b)
LPG rail loading/unloading station shall be located on a separate rail spur and shall not be grouped with other products.
(c)
LPG loading/unloading rail gantries shall be separated from other rail shunting facilities by a minimum distance of 50m, except relating to service for the same gantry.
Rail loading/unloading of LPG should be restricted to a maximum of half rake, presently capacity of which is 500 MT. If full rake loading/unloading is envisaged, this shall be done on two separate rail gantries having a minimum distance of 50m. In case of 8 wheeler wagons half rake unloading/ loading capacity shall be 600 MT.
8.2 INTERDISTANCES FOR LPG FACILITIES Interdistances for LPG facilities shall be as given in Table-7.
TABLE - 7 INTERDISTANCES FOR LPG FACILITIES S.No.
From \ To
1
2
3
4
5
6
7
1.
LPG Storage vessels
*
T8
30
30
30
15
60
2.
Boundary/property line/ group of buildings, not associated with LPG plant
T8
-
30
30
30
30
**
3.
Shed-LPG/Cold repair shed/ cylinder evacuation facilities
30
30
15
30
30
15
60
4.
Tank Wagon Gantry Tank Truck Gantry
30
30
30
50
50
30
60
5.
Rail spurs
30
30
30
50
50
30
60
6.
Pump house/Comp. house(LPG)
15
30
15
30
30
-
60
7.
Fire Pump house
60
**
60
60
60
60
-
Notes : 1.
All distances are in metres.
2.
Notation: T8 – Refer Table - 8
3.
*
1/4 of sum of diameters of adjacent vessels or half the diameter of the larger of the two adjacent vessels whichever is greater.
**
Any distance for operational convenience.
Distance of stabling line shall be as per minimum Railway Standards.
OISD-STD-118 Revision - II
29
TABLE - 8 (NOTE1) INTERDISTANCES BETWEEN LPG STORAGE VESSELS AND BOUNDARY / PROPERTY LINE / GROUP OF BUILDINGS NOT ASSOCIATED WITH LPG FACILITIES
Capacity of Each Vessel (Cum.M. of water)
Distance
1.
10 - 20
15
2.
21 - 40
20
3.
41. 350
30
4.
351 - 450
40
5.
451 - 750
60
6.
751 - 3800
90
S.No.
Note : All distances are in metres.
9.0
LAYOUT OF UTILITY STATIONS
9.1
GENERAL CONSIDERATIONS
The waste disposal facilities like effluent channels, land fill areas for disposing off solid waste etc. should preferably be located by the side of boundary wall, but down stream of wind direction so that the foul odour that may be present at times does not affect the plant personnel and neighbourhood areas. Locating the waste disposal facility near the boundary wall also eliminates the vehicular movement in process areas in case solid wastes are to be taken out of installation for disposal.
Boiler House, Air compressors, fuel oil facilities (for generation of steam) shall be located in separate block adjoining the process unit blocks. The steam generation facilities block should preferably include boiler feed water pump, chemical block for boiler house etc., which form the integral part of the steam generation facilities. The plant air compressors and drying units should preferably be located in the boiler house unit block. Fuel oil heating and pumping facilities may also be located within the boiler house unit block. These may be located in the boiler house unit block to minimise the spreading ofvarious utility blocks around the process unit, to facilitate ease of operation. ( i)
Smoking booths should not be provided in hydrocarbon industry. However if it is necessary to provide smoking booths, these should be located at a safe distance of : (i)
30m from hydrocarbon source in case of oil refinery/storage installation.
(ii)
60m from hydrocabon source in case of LPG/Gas Processing Plants.
9.2
INTERDISTANCES Interdistances between various utility stations and other facilities shall be as given in Table-1.
10.0 REFERENCES 1.
OISD-STD-106 on Process Design and Operating Philosophies on Relief and Disposal Systems.
2.
OISD-STD-144 Distribution.
3.
NFPA Standard No.30 "Flammable and Combus-tible Liquids Code".
4.
Petroleum Rules - 1976.
5.
OISD-STD-117on Fire Protection facilities for Petroleum depots and terminals.
6.
OISD-STD-116 on Fire Protection facilities for Petroleum Refineries/process plants.
7.
SMPV Rules - 1981.
COOLING TOWERS Cooling towers should be located away from process unit area, preferably downstream direction of wind to avoid corrosion of the equipments in process areas.
(iii)
SMOKING BOOTHS
ELECTRICAL Electrical generation facilities should be located near the process unit block because such electrical generation units normally supply steam to the process units e.g. Cogeneration. When external power grid is interconnected with plant power generation facilities, either the power plant shall be located at the side of boundary wall or the external power transmission lines shall be taken underground upto the interconnection grid inorder to minimise the length of overhead transmission lines within the plant.
(ii)
iv)
WASTE DISPOSAL FACILITIES Separate collection system should be provided for different types of waste generated in the process plant such as oily water, cooling tower blowdown, caustic and acidic effluents, sludge, fecal etc.
on
LPG
Bottling
and
OISD-STD-118 Revision - II
31 ANNEXURE - 1
TYPICAL LAYOUT OF LPG STORAGE VESSELS
Section - XX NOTES : 1.
ALL DIMENSIONS ARE IN METRES
2.
TOP SURFACE OF ALL VESSELS INSTALLED SHALL BE IN THE SAME PLANE.
3.
SIZING CRITERIA FOR SUMP—FULL CONTAINMENT OF LPG SPHERE WITHIN KERB AREA IS NOT ENVISAGED HOWEVER THERE IS CHANCE OF SMALL SPILL OFLPG IN THE STORAGE AREA IT IS ASSUMED THAT THE LEAK WILL BE ARRESTED WITHIN ABOUT AN HOUR THE CONTAINMENT VOLUME FOR ONE HOUR LEAK CORRESPONDING TO LARGEST NOZZLE SIZE AND LIGHTEST MATERIAL IS 18 MT OR ABOUT 35 M3 WITH A MAXIMUM LIQUID COLLECTION RATE OF APPROX. 5 KG./SEC.
4.
ALL LEVELS ARE WITH RESPECT TO HIGH POINT OF PAVEMENT LEVEL I.E. 100.00
5.
PROTECTIVE WALLS TO BE PROVIDED IF THE VALVE IS WITHIN 30 M FROM SPHERE SHELL.
6.
WATER SEAL SHALL BE PROVIDED AT OUTLET FROM SHALLOW SUMP.
LEGEND :
DVA Deluge Valve Assembly ........ Fire Water Piping (Not to Scale)
