1

Barauni Refinery

Barauni Refinery was built in collaboration with Russia and Romania. Situated 125 kilometers

from Patna, Barauni Refinery was commissioned in 1964 with a refining capacity of 1 Million

Metric Tonnes Per Annum (MMTPA). It was dedicated to the Nation by the then Union Minister

for Petroleum, Prof. Humayun Kabir in January 1965. After de-bottlenecking, revamping and

expansion projects, its current capacity 6 MMTPA. With various revamps and expansion projects

at Barauni Refinery, capability for processing high-sulphur crude has been added, thereby

increasing not only the capacity but also the profitability of the refinery.

Barauni Refinery was initially designed to process low sulphur crude oil (sweet crude) of Assam.

After establishment of other refineries in the Northeast, Assam crude is unavailable for this

refinery. Hence, sweet crude is being sourced from African, South East Asian and Middle East

countries. The refinery receives crude oil by pipeline from Paradip on the east coast via Haldia.

Matching secondary processing facilities such Resid Fluidized Catalytic Cracker (RFCC), Diesel

Hydrotreater (DHDT), Sulphur Recovery Unit (SRU) have been added. These state-of-the-art

eco-friendly technologies have enabled the refinery to produce green fuels complying with

international standards. The third reactor has been installed in the DHDT unit of Barauni

Refinery to produce Diesel that complies with the Bharat Stage-III auto fuel emission norms.

The MS Quality Up gradation project of Barauni Refinery is in full swing to supply Bharat

Stage-III compliant petrol to the market.

NOTE: - THE STUDY IS LIMITED TO BARAUNI REFINERY AND ALL THE DATA

DISPLAYED IN THIS REPORT IS LIMITED TO BARAUNI REFIENRY.

2

GENERAL CLASSIFICATION OF PETROLEUM PRODUCTS

o Petroleum products are classified according to their closed cup FLASH POINTS

as follows:

o Class Petroleum: Liquids which have flash point below 23 degrees C.

o Class 'B' petroleum: Liquids which have flash point of 23 degrees C and above

but below 65 degrees C.

o Class 'C' petroleum: Liquids which have flash point of 65 degrees C and above

but below 93 degrees C.

o Excluded Petroleum: Liquids which have flash point of 93 degrees C and above.

o Liquefied gases including LPG, do not fall under this classification but form a

separate category.

CLASSIFICATION OF FIRES

Class A Fires: Fires involving combustible materials of organic nature, such as

wood, paper, rubber and many plastics, etc., where the cooling effect of water is

essential for extinction of fires.

Class B Fires: Fires involving flammable liquids, petroleum products, or the like,

where a blanketing effect is essential.

Class C Fires: Fires involving flammable gases under pressure including liquefied

gases, where it is necessary to inhibit the burning gas at a fast rate with an inert gas,

powder or vaporizing liquid for extinguishment.

Class D Fires : Fires involving combustible materials such as magnesium,

aluminum, zinc, sodium, potassium when the burning metals are reactive to water

and water containing agents, and in certain cases carbon dioxide, halogenated

hydrocarbons and ordinary dry powders. These fires require special media and

technique to extinguish.

3

FIRE PROTECTION PHILOSOPHY

The Fire Protection Philosophy is based on Loss Prevention and Control. The importance of

adequate fire protection facilities for hydrocarbon processing plants need not be emphasized as

any plant is absolutely safe because of the inherent hazard it carries. A fire in one part/section of

the plant can endanger other sections of plant as well. If fire breaks out, it must be controlled /

extinguished as quickly as possible to minimize the loss to life and property and to prevent

further spread of fire.

GENERAL CONSIDERATIONS

Special considerations shall be given to the size of process plant, pressure and temperature

conditions, size of storage, plant location and terrain, as these determine the basic fire protection

need. Layout of an installation shall be done in accordance with OISD-Standard-118 on Layouts.

A good layout provides adequate fire fighting access, means of escape in case of fire and also

segregation of facilities so that the adjacent facilities are not endangered during a fire.

The following fire protection facilities shall be provided depending upon the nature of the

installation and risk involved.

- Fire Water System

- Foam System

- Halon / its proven equivalent System

- Carbon Dioxide System

- Dry Chemical Extinguishing System

- Detection and Alarm system

- Communication System

- Portable firefighting equipment

- Mobile firefighting equipment

DESIGN CRITERIA

The following shall be the basic design criteria for a fire protection system.

i) Facilities should be designed on the basis that city fire water supply is not available

close to the installation.

ii) Fire protection facilities shall be designed to fight two major fires simultaneously

anywhere in the installation.

iii) All the tank farms and other areas of installation where hydrocarbons are handled,

shall be fully covered by hydrant System.

iv) Class petroleum storage in above ground tanks shall have fixed water spray system,

whether floating roof or fixed roof.

4

v) Class 'B' petroleum storage tanks of following dimensions shall be provided with

fixed water spray.

- Floating roof tanks of diameter larger than 30 mtrs.

- Fixed roof tanks of diameter larger than 20 mtrs

vi) a. Semi-fixed foam system shall be provided for the following tanks.

Floating roof tanks storing Class 'A' and Class 'B' petroleum products.

- Fixed roof tanks storing Class 'A' and class 'B' petroleum products.

- Fixed roof tanks storing class 'C' petroleum products, of diameter larger than 40 mtrs.

b. Automatic Actuated Foam Flooding Proven System may be provided:

- On existing floating roof tanks where Semi-fixed foam system could not be provided.

- on floating roof tank larger than 60 mtrs diameter( as an alternative to halon/its

proven equivalent system)

vii) LPG Pressure storage vessels shall be provided with automatic water spray system.

viii) Water spray system shall be considered for hazardous locations and equipment in

process unit areas. Some of these areas are:

- Uninsulated vessels containing class A or B flammable liquid having capacity larger

than 50 m3

- Vessels inaccessible to fire tender/ mobile equipment, fire hydrants

- Pumps handling petroleum products class 'A' under pipe racks

- Pumps handling products above auto-ignition temperature under pipe racks

- Air fin coolers located above pipe racks.

- Automatic water spray system shall be provided in LPG bottling stations, LPG

loading/unloading gantries and LPG pump and compressor areas in all new refineries

and for existing refineries this conversion to automatic shall be done in phased

manner.

- Water spray requirement may be considered for transformers more than 10 MVA.

Halon / its proven equivalent fire

ix) Protection system should be provided for process control rooms, computer rooms and

pressurised rooms.

x) Oil loading/unloading Tank Truck & Tank Wagon Gantries shall be provided with water

spray and/or foam system.

5

FIRE WATER SYSTEM

Water is an essential and the most important medium available for fire protection. Water

is used for fire extinguishment, fire control, cooling of equipment and protection of

equipment and personnel from heat radiation. For these purposes water is used in various

forms such as straight jet, water fog, water curtain, water spray, deluge/ sprinkler, for

foam making etc.

The main components of the fire water system are fire water storage, fire water pumps

and distribution piping network along with hydrants and monitors.

FLOW RATE

Two of the largest flow rates calculated for different sections as shown below shall be

added and that shall be taken as design flow rate. A typical example for calculating

design fire water flow rate is given in Annexure-1.

i) Fire Water flow rate for tank farm shall be aggregate of the following:

- Water flow calculated for cooling a tank on fire at a rate of 3 Ipm/m2 of tank shell

area.

Water flow calculated for all other tanks falling within a radius of (R+30) mts from centre of the

tank on fire and situated in the same dyke area, at a rate of 3 Ipm/m2 of tank shell area.

- Water flow calculated for all other tanks falling outside a radius of (R+30) mts from

centre of the tank on fire and situated in the same dyke area at a rate of 1 Ipm/m2 of

tank shell area.

- Water flow required for applying foam into a single largest cone roof or on a floating

roof tank (after the roof has sunk) burning surface area of oil by way of fixed foam

system, where provided, or by use of water/foam monitors. (Refer section 6.8 for

foam rates).

- Fire water flow rate for supplementary stream, shall be based on using 4 single

hydrant outlets and 1 monitor simultaneously. Capacity of each hydrant outlet as 36

m3/hr and of each monitor as 144 m3/hr may be considered at a pressure of 7

kg/cm2g.

ii) Fire water flow rate for LPG sphere storage area shall be aggregate of the following:

- Water flow calculated for cooling LPG sphere on fire at a rate of 10.2 Ipm/ m2 of

sphere surface area.

- Water flow calculated for all other spheres falling within a radius of (R+30) mts from

centre of the sphere on fire at the rate of 10.2 Ipm/m2 of surface area.

- If the water rate as calculated above works out to be more than 2000 m3/hr the layout

of the spheres should be reviewed.

- Water flow for supplementary stream shall be considered as 288 m3/hr as indicated

6

under item (i).

- The spheres should be laid in two separate groups with each group limited to a

maximum of 6 vessels The groups shall preferably be separated by a distance of

(R+30) mts.

iii) Water flow rate requirements for fire fighting in other major areas shall be calculated based

on criteria.

HEADER PRESSURE

The fire water system shall be designed for a minimum residual pressure of 7.0 kg/cm2 g

at the hydraulically remotest point of application at the designed flow rate at that point.

The fire water network shall be kept pressurized at minimum 7.0 kg/cm2 gat all the time.

In existing refineries, this shall be achieved in a phased manner.

STORAGE

Water for the hydrant service shall be stored in any easily accessible surface or

underground lined reservoir or above ground tanks of steel, concrete or masonry. The

effective capacity of the reservoir above the level of suction point shall be minimum 4

hours aggregate working capacity of pumps. Where make up water supply system is 50%

or more this storage capacity may be reduced to 3 hours aggregate working capacity of

pumps. Storage reservoir shall be in two equal interconnected compartments to facilitate

cleaning and repairs.

Large natural reservoirs having water capacity exceeding 10 times the aggregate water

requirement of fire pumps may be left unlined.

In addition to fire water storage envisaged as above, emergency water supply in the event

of depletion of water storage shall be considered. Such water supplies may be connected

from cooling water supply header and/or treated effluent discharge headers.

Fire water supply shall be preferably from fresh water source such as river, tube well or

lake. Where fresh water source is not easily available, fire water supply may be sea water

or other acceptable source like treated effluent water.

PUMPS

Fire water pumps shall be used exclusively for fire fighting purposes.

Type of Pumps

Fire water pumps shall be of the following type:

i) Electric motor driven centrifugal pumps

ii) Diesel engine driven centrifugal pumps

7

The pumps shall be horizontal centrifugal type or vertical turbine submersible pumps.

The pumps shall be capable of discharging 150% of its rated capacity at a minimum of

65% of the rated head. The shut-off head shall not exceed 120% of rated head, for

horizontal pumps and 140% in case of vertical turbine type pumps.

Capacity of Pumps

The capacity and number of main fire water pumps shall be fixed based on design fire

water rate, to be worked out on the basis of design criteria as per section 5.2. The

capacity of each pump shall not be less than 400 m^hr nor more than 1000 cu.mt/hr. All

pumps should be identical with respect to capacity and head characteristics.

Standby pumps

i) When total number of Working pumps work out to be one or two, 100% standby

pumps shall be provided.

ii) When total number of working pumps is more than two, 50% standby pumps shall be

provided.

No. of diesel driven pumps shall be minimum 50% of the total no. of pumps and diesel pump

capacity shall also be minimum 50%. Power supply to the pump motors should be from two

separate feeders.

Jockey Pumps

The fire water network shall be kept pressurised at minimum 7.0 kg/cm2 g by jockey

pumps. 2 Jockey pumps (1 working plus 11 standby) shall be provided. The capacity of

the pump shall be sufficient to maintain system pressure in the event of leakages from

valves etc. The capacity of jockey pumps shall be 3% (minimum) and 10% (maximum)

of the design fire water rate and its head higher than the main fire water pumps.

8

BRIEF DESCRIPTION OF FIRE FIGHTING FOAM

FIRE FIGHTING FOAM:

Fire fighting foam is a homogeneous mass of tiny air or gas filled bubble of low specific

gravity, which when applied in correct manner and in sufficient quantity, forms a

compact fluid and stable blanket which is capable of floating on the surface of flammable

liquids and preventing atmospheric air from reaching the liquid.

TYPES OF FOAM COMPOUND

Two Types of foams are used for fighting liquid fires:

CHEMICAL FOAM:

When two or more chemicals are added the foam generates due to chemical reaction.

The most common ingredients used for chemical foam are sodium bicarbonate and

aluminimum sulphate with stabilizer. The chemical foam is generally used in Fire

extinguishers.

MECHANICAL FOAM:

It is produced by mechanically mixing a gas or air to a solution of foam compound

(concentrate) in water. Various types of foam concentrates are used for generating foam,

depending on the requirement and suitability. Each concentrate has its own advantage

and limitations. The brief description of foam concentrates is given below.

MECHANICAL FOAM COMPOUND:

Mechanical foam compound may be classified in to 3 categories based on it's expansion

ratio.

LOW EXPANSION FOAM:

Foam expansion ratio may be up to 50 to 1, but usually between 5:1 to 15:1 as typically

produced by self aspirating foam branch pipes.

The low expansion foam contains more water and has better resistant to fire. It is suitable

for hydrocarbon liquid fires and is widely used in oil refinery, oil platforms,

petrochemical and other chemical industries.

9

MEDIUM EXPANSION FOAM:

Foam expansion ratio vary from 51:1 to 500:1 as typically produced by self aspirating

foam branch pipes with nets. This foam has limited use in controlling hydrocarbon liquid

fire because of its limitations w.r.t. poor cooling, poor resistant to hot surface/radiant heat

etc.

HIGH EXPANSION FOAM:

Foam expansion ratio vary from 501:1 to 1500:1, usually between 750:1 to 1000:1 as

typically produced by foam generators with air fans. This foam has also very limited use

in controlling hydrocarbon liquid fire because of its limitations w.r.t. poor cooling, poor

resistant to hot surface/radiant heat etc. It is used for protection of hydrocarbon gases

stored under cryogenic conditions and for warehouse protection.

TYPES OF LOW EXPANSION FOAM

PROTEIN BASE FOAM:

The foam concentrate is prepared from hydrolyzed protein either from animals or

vegetable source. The suitable stabilizer and preservatives are also added.

The concentrate forms a thick foam blanket and is suitable for hydrocarbon liquid fires,

but not on water miscible liquids. The effectiveness of foam is not very good on deep

pools or low flash point fuels which have had lengthy pre burn time unless applied very

gently to the surface.

The concentrate is available for induction rate of 3 to 6%. The shelf life of concentrate is

2 years.

FLUORO PROTEIN FOAM:

This is similar to protein base foam with fluro-chemical which makes it more effective

than protein base foam.

The concentrate forms a thick foam blanket and is suitable for hydrocarbon liquid fires,

but not on water miscible liquids. The foam is very effective on deep pools of low flash

point fuels which have had lengthy pre burn time.

The concentrate is available for induction rate of 3 to 6% and the shelf life is similar to

that of protein base foam.

10

AQUEOUS FILM FORMING FOAM (AFFF):

The foam concentrate mainly consists of fluoro -carbon surfactants, foaming agent and

stabilizer.

This can be used with fresh water as well as with sea water.

It produces very fluid foam, which flows freely on liquid surface. The aqueous film

produced suppresses the liquid vapour quickly. The foam has quick fire knock down

property and is suitable for liquid hydrocarbon fires. As the foam has poor drainage rate,

the effectiveness is limited on deep pool fires of low flash point fuels which have lengthy

pre burn time.

The concentrate is available for induction rate of 3 to 6% and the shelf life is more than

10 years.

This can also be used with non aspirating type nozzles.

MULTIPURPOSE AFFF:

Multipurpose AFFF concentrate is synthetic, foaming liquid designed specially for fire

protection of water soluble solvents and water insoluble hydrocarbon liquids. This can be

used either with fresh water of sea water.

When applied it forms foam with a cohesive polymeric layer on liquid surface, which

suppresses the vapour and extinguishes the fire. The foam is also suitable for deep pool

fires because of superior drainage rate and more resistive to hot fuels/radiant heat.

The 3% induction rate is suitable for liquid hydrocarbon fires and 5% for water miscible

solvents. The shelf life of concentrate is not less than 10 years. This can also be used

with non aspirating type nozzles.

FILM FORMING FLOURO PROTEIN (FFFP);

FFFP combines the rapid fire knock down quality of conventional film forming AFFF

with the high level of post fire security and burn back resistance of flouro protein foam.

The concentrate can either be used with fresh water or sea water.

The foam is suitable for hydrocarbon liquid fires including deep pool fires of low flash

point fuels which have had lengthy pre burn time.

The concentrate is available for induction rate of 3 to 6% and the shelf life is not less than

5 years. This can also be used with non aspirating type nozzles.

11

TYPES OF MEDIUM AND HIGH EXPANSION FOAM:

Synthetic foam concentrate is used with suitable devices to produce medium and high

expansion foams. This can be used on hydrocarbon fuels with low boiling point. The

foam is very light in weight and gives poor cooling effect in comparison to low

expansion foams. The foam is susceptible to easy break down by hot fuel layers and

radiant heat.

The induction rate in water may vary from 1.5 to 3%.

Many of the low expansion foam concentrate can also be used with suitable devices to

produce medium / high expansion foam.

12

Fire Fighting Facilities in Tank Farm Area

SCOPE

This section deals with the basic concepts that affect the selection of storage modes for

refineries. There are three basic modes of storage: atmospheric, pressure, and refrigerated.

Design and selection criteria for atmospheric, pressure and refrigerated storage depend on the

type of product that is stored.

BACKGROUND

The choice of storage mode is governed by safety requirements associated with the physical

properties (e.g., vapor pressure) of the material to be stored. Economics and environmental

requirements are secondary considerations.

DEFINITIONS

PRINCIPAL TYPES OF ATMOSPHERIC STORAGE TANKS

The two principal types of atmospheric storage tanks are fixed roof and floating roof. A brief

description of each type follows:

FIXED ROOF TANKS

This type of tank has a fixed roof that is in the form of a cone or dome. The roof can be

designed to be self-supporting in the smaller sizes, but is normally supported by columns in the

larger diameter tanks. The tank operates with a vapor space, which changes in volume when the

liquid level moves. Roof vents are provided to allow for vapor emission and to maintain the tank

at atmospheric pressure.

Fixed roof tanks may be either inert gas-blanketed or vapor space enriched if they for

example contain low vapor pressure stocks sensitive to degradation by oxygen or contain high

flash stocks stored within 15°F (8°C) of their flash point.

FLOATING ROOF TANKS

The floating roof tank is constructed so that the roof floats on the liquid surface. This eliminates

the vapor space and greatly reduces vapor loss. The three principal types of floating roofs are

single deck pontoon, double deck and internal floating roof. A brief description of each type

follows:

13

Single Deck Pontoon Roof - The single deck pontoon roof consists of a flat center deck

surrounded by pontoons that are divided radially into a number of compartments. Because the

roof is exposed to the weather, adequate drainage facilities and buoyancy requirements must be

provided per API 650. IP 9-4-1 covers the additional requirements for sizes larger than 60 ft (18

m) in diameter. External pan type (without pontoons) floating roofs are not acceptable due to the

ease of sinking the roof.

SELECTION OF THE TYPE OF ATMOSPHERIC TANK

For a given application, the designer will have to choose from among the types of atmospheric

storage tanks described above, based on the service requirements, the characteristics of the

material to be stored and any other special local considerations. Note especially that local laws

governing air pollution control, fire protection and safety must be taken into account to insure

that the storage facilities selected will comply.

The following guidelines concern the choice between fixed roof and floating roof.

EXTERNAL FLOATING ROOF TANKS

Floating roof tanks should be used for the services listed below. This summary is based on

experience, safety considerations and economic studies.

Static Accumulators - Stocks that are classified as intermediate vapor pressure static

accumulators.

Minimizing the Risks of Fire, Explosion or Accident.

Flash Point - Stocks which are to be stored at temperatures within 15°F (8°C) of their flash

points, or higher.

Type of Stock - All crude oil stocks.

Tank Size - All tanks with diameters exceeding 150 ft (45 m), if they are to contain low-flash

stocks (flash point 100°F [38°C] or below). Within recent years, low flash stocks have been

stored in floating roof tanks regardless of diameter to limit fire risk and environmental concerns.

Oxygen Sensitivity - High vapor pressure stocks which are sensitive to degradation by oxygen

(e.g., coker naphtha). For this service, the toroidal type of seal is preferred. (Low vapor pressure

stocks, which are oxygen-sensitive, should be stored in fixed roof tanks with nitrogen or inert gas

blanketing.)

Other - Special considerations may require storage in fixed roof tanks or fixed roof tanks with

internal floating roofs. Examples include the use of cone roof tanks with vapor recovery for high

14

RVP stocks due to stringent hydrocarbon emissions requirements. Also, due to a combination of

snow loads (which dictated the need for fixed roofs) and location within an earthquake zone

(which raised the concern of floating roofs hanging up due to out of roundness tank walls), the

crude tanks for the Valdez terminal were installed as vapor-blanketed, cone roof tanks

FIXED ROOF TANKS

Fixed roof tanks are used for all atmospheric storage where floating roofs are not required or not

practical. They are also usedwhere inert gas blanketing or vapor space enrichment is required.

Examples of these situations are:

1. Low vapor pressure stocks subject to stringent hydrocarbon emission requirements or sensitive

to degradation by oxygen.

2. High flash stocks stored within 15°F (8°C) of flash point (hot tanks).

3. Areas of high seismic activity where there is a concern that floating roofs may hang up due to

out of roundness of tank walls.

4. Future restrictions in environmentally stringent areas may require fixed roof tanks, vapor

balanced with loading facilities and vapor recovery. Floating roof designs may not be adequate

even if equipped with secondary seals.

5. For products that cling to the shell walls and would prevent the free movement of a floating

roof, for example asphalt.

ATMOSPHERIC TANKAGE

Tanks storing flammable petroleum or petrochemical materials at atmospheric pressure are

subject to the inherent hazards of (a) uncontrolled release by ―frothover," rollovers, overfilling or

other spills, or excessive vapor evolution through vents; and (b) internal explosion, if a

flammable mixture in a tank vapor space is ignited.

Occurrence of Tankage Hazards

Tankage hazards may arise as the result of the following operating mechanisms:

1. Frothover - A frothover occurs when the temperature of a tank is sufficient to boil any water

that is present in it. The generation of steam below the surface of the oil results in the formation

of oil froth, often with sufficient violence to rupture the weak shell-roof weld seam of a cone

roof tank. The resulting spill of low density oil froth may rapidly fill and overflow the tank dike

and spread to a source of ignition, causing a major fire. Frothovers are usually caused by:

a. Routing water or a stream containing water into a ―hot" tank [i.e., a tank operating above

265°F (130°C)]. This may be the result of incorrect stream routing, or heat exchanger tube

15

leakage if the plant stream to the hot tank passes through water cooled exchanger with higher

pressure on the water side.

b. Light hydrocarbons inadvertently routed to ―hot" tanks have the same effect as water.

Incorrect routing or exchanger leakage may be the basic cause, as above.

c. Routing a hot stream to a ―cold" tank [i.e., a tank normally operating below 200°F (93°C)]

long enough to raise the tank temperature to the boiling point of the water present in the tank

bottom. This may be the result of incorrect stream routing, or the loss of cooling capacity on a

plant product stream.

Rollovers - The rollover phenomenon is characterized by a sudden rapid generation of vapor and

has occurred in LNG and slop tanks where streams of different densities have been added,

forming layers. In the case of LNG, a lower heavier layer will gradually warm and its density

approach that of the lighter layer above until it suddenly rises and produces rapid vaporization.

Good mixing during tank filling and capability for recirculation are needed to prevent this

rollover.

In the case of slop, thermal convection between light and heavy layers may be limited by

emulsions until heating causes the lower layer to rise suddenly and produce rapid vaporization of

the lighter layer. For this reason, storage or heating of light and heavy slop in the same tank

should be avoided.

Overfilling and Other Tank Spills - Fire hazards may also arise from other types of spillage of

tank contents into the surrounding area. These may include:

a. Overfilling.

b. Failure of tank connections or associated piping.

c. Unattended withdrawal of water from the tank bottom.

d. Failure of a floating roof water drain, with the external drain valve left open.

e. Sinking of a floating roof, due to mechanical failure or accumulation of water, resulting in the

hazardous exposure of the whole liquid surface.

Excessive Vapor Evolution - A limit of 13 psia (90 kPa abs) true vapor pressure at storage

temperature is established to define the lightest petroleum fraction which can be safely stored in

atmospheric tankage without risk of excessive vapor evolution. If, however, lighter

hydrocarbons are routed into an atmospheric tank, or if the tank temperature is allowed to rise

such that the true vapor pressure of the contents approaches atmospheric pressure, then a

hazardous uncontrolled release of hydrocarbon vapor from the tank vent will result. If the vapor

evolution exceeds the vent capacity on a floating roof tank the roof can tilt or sink. The basic

cause of such incidents may be incorrect stream routing, faulty upstream blending operations,

16

exchanger tube leakage, loss of level or loss of stabilization in upstream process plant, or loss of

cooling capacity on a plant product stream. When loss of level in an upstream process vessel

would allow pentane or lighter materials to enter tankage, a low level cutout should be installed

in the rundown line, set below the setting of the low level alarm.

Internal Explosion - Except during initial filling operations, before the roof is floated, external

floating roof tanks do not contain a vapor space and are, therefore, not subject to internal

explosion. Routine landing of a floating roof on its legs should be avoided since this would

create a potentially explosive vapor space each time it occurs. This is particularly applicable to

internal floating covers or pan roofs, since displaced vapors beneath the cone-roof take longer to

dissipate.

In a cone-roof atmospheric tank, however, the vapor space consists of a vapor-air mixture, the

composition depending on the quality and temperature of the liquid in the tank and the physical

operations involved (e.g., filling, emptying, and mixing).For certain petroleum fractions (e.g.,

turbo jet fuel), the vapor space is in the flammable range at normal storage temperatures, and is

therefore subject to the risk of internal explosion if an ignition source (e.g., electrostatic

discharge or lightning) is present. In considering the explosion hazard in cone roof tanks it must

be recognized that the vapor composition may vary appreciably from the normal composition as

a result of contamination or upstream plant problems, in the same way as described in Paragraph

(4), above. A particular example of this occurs with products from hydrogen treating processes,

where inadequate stripping may result in entrainment of hydrogen into the receiving tanks.

Safety Features in Tank Design

To minimize the hazards described above, the design of refinery and chemical plant tankage

facilities must include the features listed below. Safety design of tankage for marketing

installations follows the same general principles but may differ in some details, e.g., spacing.

Eliminate Ignition Sources - In addition to the elimination of electrostatic discharges, as

described above, protection against ignition by lightning or electrical equipment sparking must

be provided, as described under MINIMIZING SOURCES OF IGNITION in this section.

Exposed surfaces of tank heaters when the liquid is at low level may also constitute an ignition

source or promote the oxidation of pyrophoric deposits. Designs should prevent the exposure of

heating surface over the normal range of the tank liquid level.

Control Rundown Streams to Tankage - The routing of streams to atmospheric tankage must

comply with the following:

a. A stream must not be routed to atmospheric tankage if its true vapor pressure at rundown

temperature is greater than 13 psia (90 kPa abs), or if it can result in the true vapor pressure of

material in the tank exceeding 13 psia (90 kPa abs).

17

b. As an exception to (a), light materials with true vapor pressure greater than 13 psia (90 kPa

abs) may be used as components for line blending systems discharging into atmospheric tankage

(as in the blending of butane into gasoline), subject to the following conditions:

(1) The true vapor pressure of the blend must not exceed 13 psia (90 kPa abs).

(2) Controls must be provided to automatically shut off the flow of light component in the event

of low flow of the base or heavy stream, or high temperature of either stream.

(3) A back pressure controller is also required to ensure good mixing and to minimize flashing

prior to entry into the tank.

c. A stream must not be designed for routing to ―cold" atmospheric tankage if its temperature is

above 200°F (93°C).

d. High-temperature alarms should be provided on all plant rundown lines to tankage where loss

of heat exchange or cooling capacity could result in any of the following:

(1) The rundown stream exceeding 13 psia (90 kPa abs) true vapor pressure.

(2) The rundown stream to a ―cold" tank exceeding 200°F (93°C).

e. Appropriate alarms and/or cutouts should be provided to give warning of process plant

conditions, which could result in

light materials being routed to atmospheric tank age. Such alarms and/or cutouts should be

treated as "safety critical" devices. Examples of such features may include low flow alarms on

stripping steam, low temperature or low flow alarms to indicate loss of stabilization, low level

alarms on vessels from which products are routed to tankage and high-temperature alarms on

streams diverted to slop by automatic controller actions. These considerations may also be

applicable to streams routed to underground pits operating at atmospheric pressure. Where

possible, plant product stream heat exchangers and coolers should be designed with the product

as the higher pressure fluid. This will minimize product quality contamination problems as well

as tankage hazards that might otherwise result from exchanger leakage.

Rundown heat exchangers can be designed with the product as the lower pressure fluid provided

that all the following design criteria and operating precautions are met:

(1) The product tank age must not have a pan type floating roof or internal floating cover.

(2) The potential vapor release rate in case of full tube rupture does not exceed 5 klb/hr (0.62

kg/sec).

(3) The peak rundown system pressure after tube rupture does not exceed 1.5 times the system

design pressure or the proof test pressure whichever is lower.

18

(4) The tank venting capability is consistent with the quantity of vapor release during a tube

rupture.

(5) The problem rundown heat exchangers can be isolated from the rest of the system to allow

timely maintenance of any leaking exchangers.

(6) All tanks susceptible to vapor release caused by tube failure are provided with a hydrocarbon

detection system around their periphery.

(7) Sampling and/or instrumentation are used to detect tube leakage.

(8) Sampling and maintenance procedures in tanks susceptible to vapor release caused by tube

rupture must assume the tank vapor space (or the vapor space above the floating roof, if

applicable) is in the flammable range.

G.Particular consideration should be given to the effects of process upsets, emergencies or partial

shutdown operations in highly integrated plants on the quality of product streams to tankage.

h. Piping systems upstream of tankage should be designed to minimize the potential for

hazardous contamination by water or light materials.

i. Streams normally routed directly from one unit to another at elevated temperatures may require

diversion to tankage in the event of shutdown of the downstream unit. Designs must include

emergency coolers and appropriate instrumentation to insure that such streams, when diverted,

are cooled below 200°F (93°C) before being routed to a ―cold" tank.

Minimize Potential for Spillage in Tank Areas

a. When new gauging facilities are being considered for atmospheric tanks which will be

monitored remotely, install independent high level alarm switches on tanks handling crude and

materials with a flash point of 100°F (38°C) or lower, and on tanks in other services where an

overfill would result in an unacceptable consequence. An example of the latter might be tankage

located near to the property fence and/or where an overfill could have an adverse environmental

impact. The high level switch should be independent of the tank gauging facilities, but the alarm

signal may be transmitted through the tank gauging transmission system provided that the data

transmission system is self-checking to alarm upon a major component malfunction.

Normal day-to-day operations should not cause the independent high level alarm to sound. The

alarm set point should be above the maximum permissible filling height. The independent high

level alarm should only sound if there has been an instrument or operator failure and the tank is

being filled above the maximum filling height. It should cause an operator to take immediate

action to correct the situation, and not be a normal sounding alarm, which is heard routinely and

may therefore be ignored.

19

The alarm originating from independent high-level switches should be both audible and visible

to the operator. It should also be of the type that must be acknowledged to silence. The audible

independent high-level alarm (horn or voice synthesizer) must be distinctive from lower priority

and audible alarms. This requirement exists for hard-wired alarms and for alarms transmitted via

a data collection system. Each tank in alarm condition must have a maintained display indicating

the tank identification.

In regard to the definition of remotely monitored, this would include locations that do not rely on

operators to manually gauge the tank. Remotely monitored locations could use operators to line

up pumping operations and then leave the tankage area during the majority of the operation and

provide surveillance from the control house. Locations where operators are not normally present

in the tank farm, but only spot check occasionally, would be classified as remotely monitored.

Existing atmospheric tanks, which are continuously monitored by a sophisticated computer

system through an automatic tank level gauge, may provide a comparable level of protection so

that an independent high level switch shall be a local option. Other existing tankage should be

reviewed in the long range plans to establish the level of retrofit that is desirable based on local

conditions.

b. Design tankage piping systems to minimize vulnerability to mechanical damage or fire

exposure. Within plant limits, piping systems should be above ground to minimize corrosion and

avoid underground leaks, which create safety and environmental concerns.

c. Provide safe means of water withdrawal and disposal from tank bottoms. Normally, the line

from the drain valve discharges open-ended into a small catch basin with an 8 in. (200 mm) toe-

wall (to exclude storm water) located adjacent to the tank, and connected to the oily water sewer

system. Alternatively, if the dike enclosure is drained by a catch basin to the oily water sewer,

then the tank water drawoff may discharge to this catch basin.

d. In waxy or viscous services (e.g., some crude oils, where appreciable quantities of water-oil

interface material must be withdrawn), a closed drainage system should be provided, with heated

separating tank and oil recovery facilities.

e. Provide safe and reliable means of water drainage from the roofs of floating roof tanks.

Articulated pipe drains, with a check valve at the inlet end, are required in accordance with GP

09-07-01. The drain valves at the tank shell should be kept closed when not in use, but approved

automatic draining devices (e.g., Russel Ball type) are an acceptable alternative in high rainfall

locations. Water from the primary drain is discharged to the ground.

Emergency drains of the open type are permitted on double deck or pontoon floating roofs

(provided that in the lattercase the pontoon area is more than 50% of the roof area).

20

f. Ensure elevations of take-offs to a vapor recovery unit (VRU), if provided, are designed such

that any tank overfill will not run preferentially to the VRU rather than into the diked area via the

tank vents.

TYPICAL EXAMPLE FOR CALCULATION OF FIRE WATER FLOW RATE

1. DESIGN BASIS

The fire water system in an installation shall be designed to meet the fire water flow

requirement of fighting one major fire.

2. FIRE WATER DEMAND FOR MAJOR FIRES

Consider various areas under fire and calculate fire water demand for each area based on

design basis.

2.1 FLOATING ROOF TANK PROTECTION

Data

Total storage capacity in

One dyke area = 32,000m3

No. of tanks = 2

Capacity of each tank = 16,000m3

Diameter of each tank = 40m.

Height of tank = 14.4m

a) Cooling water requirement

Cooling water rate = 3 lpm/m2 of tank area for tank on fire.

Cooling water required = p x 40 x 14.4 x 3

= 5426 lpm

= 326 m³/hr.

21

Assuming that second tank is located within the tank dyke at a distance more than 30m

from the tanks shell. Therefore, in such case cooling required at the rate of 1/min/m2 of

tank shell area.

Cooling water required = p x 40 x 14.4 x 1

= 1809 lpm

= 109 m³/hr

b) Foam water requirement, water flow required for applying foam on a largest tank

burning surface area.

For floating roof tank of 40m diameter

Seal area = p x 40 x 0.8 = 101 m²

Foam solution rate @ 12 lpm/m2

Water required for foam solution application = 10 x 12 x0.97

= 1176 lpm

= 71 M3/hr

c) Total water required for

Tank cooling = 326 + 109 = 435m³/hr

Foam solution

Application = 71 m³/hr

Total = 506 m³/Hr. Say = 510 m³/hr.

22

2.2 CONE ROOF TANKS PROTECTION

Data

Total storage capacity = 50,000 m³

No. of tanks = 4 with 12500 m³ capacity each

Diameter of each tank = 37.5M

Height of each tank = 12M

a) Cooling water requirement

Cooling water rate = 3 lpm /m² of tank shell area for tank on fire.

Cooling water required = p x 37.5 x 3 x 12

= 4241 lpm

= 254 m3/hr.

Cooling water required for other tanks at the rate of 3 lpm/m3 for tanks falling within

(R + 30M) from centre of tank on fire.

= 3 x 254 = 762 m3/hr.

Total cooling water = 254 + 762 = 1016 m3/hr.

b) Foam water requirement (For 1 tank only)

Rate of foam solution = 5 lpm/m² area

Water required for Foam Sol. = p x (37.5)² x 5 x 0.97

= 5354 lpm

= 321 m³/hr.

23

c) Total water required for

Tank cooling = 1016 m3/hr

Foam solution application = 321 m3/hr

Total = 1337 m3/hr

say 1350 m3 Hr.

2.3 Pol Tank Wagon loading gantry:

Total water requirement = 918 m3/hr

2.4 FIRE WATER FOR SUPPLEMENTARY HOSE STREAMS

Water for 4 hydrant streams = 4 x 36 = 144 m3/hr

Water for 1 monitors stream 144 m3/hr

= 288 m3 / hr

3.0 TOTAL DESIGN FIRE WATER RATE

Total design fire water rate is the largest of water rates calculated as:-

Design fire water rate = 1350 m3/hr.

24

AUTOMATIC ACTUATED FOAM FLOODING SYSTEM FOR

LARGER FLOATING ROOF TANKS(PROPOSED)

The automatic actuated foam flooding system is a system designed to automatically detect and

extinguish the floating roof tank rim seal fire at its incipient stage. The system is mounted on the

roof of the tank.

The system consists of a long foam line (typically available in 40 Mts. length) laid along the tank

perimeter. The foam aspirating nozzles are mounted on the line at an interval of 2.5 mts. The

premix foam is contained in a vessel which is kept charged with nitrogen through a nitrogen

cylinder. The System is designed for minimum foam application rate of 18 lpm/m2 of rimseal

area. For effective control, foam is applied for a period of 40 seconds. Film Forming Fluro

Protein Foam (FFFP) type concentrate is normally used in the system.

The system consists of a detector network normally thermoplastic tubing type, which is kept

charged with nitrogen. In case of fire, tube ruptures and the pressure drop triggers the foam

discharge.

The provision of audio-visual alarms for different operating parameters can also be coupled with

the system.

An example of design calculation of the system for a Floating roof tank of 79 mts. dia is given

below:

DESIGN CRITERIA:

Rimseal area of Tank: ¶ X 79 X 0.3 = 74.5 M2

(Considering a flexible seal area of typically 300 mm)

Rate of Foam application @ 18 LPM/M2 = 1341 LPM

Total Foam soln. required in 40 secs. = 894 lts.

Total nos. of Modular unit required for the tank = 7

(Considering a foam vessel of 150 lts.capacity containing 135 lts. of Foam)

25

TYPICAL EXAMPLE OF FIRE CASE IN A LARGE FLOATING ROOF TANK AFTER

SINKING OF FLOATING ROOF

Example for calculation of Foam Requirement for Floating tank with Portable Monitors:

DATA

1. Diameter of Tank : 40 m

2. Type of Roof : Floating Roof

3. Foam Application Rate : 8.1 lpm ( as per NEPA-11)

Foam Solution Requirement = II x 40 x 40 x 8.1/4

= 10173.6 lpm

= 610.4 m3/hr

Say = 610 m3 /hr.

This much quantities has to be thrown over to sunken roof area with the help of external

long range high volume monitors from the road side periphery of the tank farm. The

same may be achieved by 2 nos. of 1000 gpm such monitors. In design rate calculation in

Ann.1, sinking of floating roof has not been considered, however, installation may

consider sizing the water network around tank farms to take up such load so than long

range monitors can be fed from this network by diverting other water available in

installation to tank farms in such emergency**

Foam Compound Requirement = 10173.6 x 3/100

= 305.2 lpm

Say = 305 lpm

Foam Compound Requirement for 65 minutes with 3% concentration = 305 x 65

= 19825 litres.

Say = 20,000 litres.

** If two major fire occurs in an installation with roof sinking case as one of them.

26

LPG SPHERES AREA PROTECTION

a) Data:

No. of sphere in one area = 3

Diameter of each sphere = 17 mtrs

b) Cooling water requirement :

water rate for cooling = // x172 x 10 lpm

= 9079 lpm

= 545 m3/hr

Considering other 2 spheres located within = 3 x 545 m3/hr

(R+30) mts from centre of sphere and fire

cooling water rate for 3 spheres

= 1655 m3/hr

c) Hose stream requirement = 288 m3/hr

d) Total water requirement = 1923 m3/hr

TYPICAL EXAMPLE FOR CALCULATION OF FOAM COMPOUND REQUIREMENT

1. CONE ROOF TANK PROTECTION:

i) Data :

Total Storage capacity in one dyke area = 50,000 m3

Number of tanks = 4

Diameter of each tank = 37.5 mtrs

Height of each tank = 12 mtrs

ii) The quantity of foam compound shall be calculated as follows:

27

Consider foam solution application @ 5 lpm/m2 for the liquid surface of the

single largest cone roof tank in the dyke area.

Foam solution rate = // x (37.5) 2

--------------------X 5

4

= 5522 lpm

Foam compound required = 5522 x 3 / 100

= 166 lpm

Foam compound quantity for 65 minutes = 166 x 65

= 10790 lts

iii) Consider one portable foam monitor of 2400 lpm foam solution capacity :

3% Foam compound required = 72 lpm

Foam compound required for 65 minutes = 4680 lts

iv) Consider 2 hose streams of foam with a capacity of 1140 lts/min of foam solution

capacity

3% Foam compound required = 68.4 lpm

Foam compound required for 65 minutes = 4446 lts

v) Total foam compound required for cone roof tank area Protection:

Foam compound required for Cone Roof Tank = 10790 lts.

Foam Compound required for 1 Foam Monitor = 4680 lts.

Foam Compound required for 2 hose streams = 4406 lts.

Total : 19876 lts.

Say : 20000 lts.

28

2. FLOATING ROOF TANK PROTECTION

i) Data:

Total Storage Capacity in one dyke = 120,000 m3

No. of Tanks = 2

Capacity of Each Tank = 60,000 m3

Diameter of each tank = 79 mtrs

Height of each tank = 14.4 mtrs

ii) Consider foam solution application rate of 12 lpm/m2 of seal area of the single

largest floating roof tank in the dyke area :

Seal area = // x79x0.8

= 198.5 m2

Foam solution rate = 198.5x12 lpm

= 2382 lpm

3% Foam Compound required = 71.5 lpm

Foam Compound required for 65 mins. = 4647 lts

iii) Foam Compound required for 1 foam monitor and 2 hose streams as calculated

for cone roof protection

1 Foam monitor 4680 lts

2 Hose streams 4446 lts

29

iv) Total foam compound required for floating roof tank area Protection:

Foam Compound required for Floating Roof Tank 4647 lts

Foam compound required for 1 foam monitor 4680 lts

Foam compound required for 2 hose streams 4446 lts

Total required 13773 lts

Say, 14000 lts

3. On the lines of the above example foam compound requirement should be calculated for

various dyke areas. Requirements to fight major fires in two dyke areas (with

maximum foam compound rates requirements) should be added, to arrive at the total

requirement of the installation.

For example, for 2 cone roof tank dyke areas with largest tank diameter of 37.5 mtrs in

each area, foam compound required works out as 2x20000 lts i.e 40000 lts.

Similarly for 2 floating roof tank dyke areas with largest tank diameter of 79 mtrs. in

each area, foam compound required works out as 2 X 14000 lts i.e 28000 lts.

Facility for storage tank fire

Storage tanks are provided with fixed foam line connection and fixed cooling water

system to fight tank fires. The foam is to extinguish the fire and cooling water is to

prevent spreading of fire in the neighboring tanks. Training ground may have a tank with

fixed foam installation with isolation valves on product lines.

Facility for pit fire:

During operation of the refinery, sometimes hydrocarbon liquids get released from the

process equipment and accumulate in the open areas/ pit. To fight such fires, the facility

may be provided on the ground

Facility for pipeline fires:

In the refinery equipment are connected by pipelines and to rundown the products from

the process units to storage tanks. These pipes can leak at flange joints and result in a fire.

Facilities may be provided to simulate such fires.

30

FIRE FIGHITING SYSTEMS

GENERAL

This section will discuss the general approach for fire control and extinguishment

that has been successfully adopted for use by both large and small facilities throughout

the petroleum industry. The goal of effective fire control is to extinguish a fire in the

shortest possible time, with no loss of life, and minimum loss of property. The exception

to aggressively seeking rapid extinguishment is where the fuel for the fire is a pressurized

gas or liquid release which should be allowed to burn until the source of fuel can be shut

off.

The primary objective of fire fighting is to extinguish a small fire before it expands to

become a large fire; or to control a large fire and protect adjacent exposures until

emergency response staffing is sufficient to safely mount an aggressive suppression

effort.

Most facilities have three basic types of fire-fighting equipment ready for immediate use:

A. Fixed System: A fire protection system that is permanently installed and connected to a

supply of extinguishing agent(s). These systems may be automatically or manually

activated. An example of a fixed system would be a water spray system that is supplied

directly by the plant fire water system.

b. Semi-Fixed System: A fire protection system that is permanently installed but not connected to

a supply of extinguishing agent. These systems generally require personnel to manually

connect an extinguishing agent supply to the system prior to use. An example is a tank

foam system that terminates at a connection located at the dike wall.

c. Portable Equipment: Fire suppression equipment that must be moved to the site of the fire,

manually assembled, or positioned before being put into service. It is generally stored

until needed at a location accessible to its intended users. Examples include fire trucks,

fire hose, foam monitors, fire extinguishers, and most fire department equipment. Fire

protection equipment should be kept in fully functional condition and tested periodically

in accordance with accepted procedures. In some instances, equipment may be regularly

inspected by an outside agency. Proper records should be kept of each inspection (see

NFPA 25).

WATER FOR FIRE SUPPRESSION

Water is used universally as a fire-fighting agent. It serves as a cooling, quenching,

smothering, emulsifying, diluting and displacing agent. The high latent heat of

vaporization of water (its high absorption of heat when converted to steam) makes it

particularly valuable in fighting oil, gas, and Class A fires. It is usually available, easily

handled, and when applied as a fog (finely divided spray), is effective and safe to use on

31

most petroleum fires—where it inhibits combustion by both cooling and smothering

(excluding oxygen).Water is the primary agent for cooling equipment, structures, and

tank shells that are exposed to a fire. This prevents or reduces both heat damage to

equipment and overpressure that results from overheating vessel contents. When used as

a coarse high-velocity spray stream, water can sweep pools of burning fluid out from

under elevated equipment. Extinguishment will result if the fuel surface can be cooled

below the temperature at which it will give off sufficient vapor to support combustion

(fire point). The proper way of applying water for extinguishment is in the form of a

spray. If a water spray is properly applied to the surface of a burning liquid hydrocarbon

with a flash point above 200°F (93°C), it can produce a layer of froth on the liquid

surface, which will act similar to foam and smother the fire. Fighting a hot asphalt tank

fire is an example. However, care must be used to prevent slopover.Spills of flammable

liquid that are soluble in water may, in some instances, be extinguished by dilution. This

same approach may be impossible on fires within tanks because overfilling may occur

before sufficient dilution is achieved. The quantity of water required to extinguish a fire

by dilution varies with the solubility of the products and is generally quite large. For

example, a solution of 75 percent water and 25 percent ethyl alcohol will support

combustion when hot. As a result, for soluble materials it is generally impractical to

extinguish fires involving deep liquid spills, and those within tanks, by dilution with

water because fire spread and tank overfilling may occur before sufficient dilution is

achieved. Water is used as a displacement medium in leaking hydro-carbon lines. It may

also be used to float liquid hydrocarbons above a leak in a tank to replace product leakage

with water leakage. To be effective in pressurized pipes and tanks, the water pressure

must be greater than product pressure. Care should be taken to avoid flow of a higher

pressure product into a lower pressure water system and to avoid overpressure of the

vessel and piping. Water cannot be used to displace refrigerated liquefied petroleum gas

or liquefied natural gas from a leaking pipeline if the product temperature is colder than

32°F (0°C), or for liquids that have a temperature above 200°F (93°C). By cooling

exposures and controlling fire intensity, water can be used effectively to control

pressurized gas or liquid fires and spill fires involving low-flash-point fuels. Water can-

not be used effectively to extinguish such fires and extinguishment may be undesirable

because of potential vapor cloud hazards. However, experienced fire-fighting personnel

can use water spray as very effective personal protection from radiant heat and flame

contact to gain access to equipment so that valves can be closed, shutting off the fuel

source for fire suppression. And, in some conditions, fire fighters can disperse moderate

quantities of escaping gas or vapor using water spray. Water is the principal ingredient in

fire-fighting foam; mixed with foam concentrate, is the most effective agent for

extinguishing large flammable liquid spill fires or tank fires.

32

DRY CHEMICALS

Application of a dry chemical can be effective in controlling and extinguishing fires occurring

during the processing and handling of flammable liquids and solids. The finely divided chemical

produces free radical interceptors which break the oxidation chain reaction, thus inhibiting the

combustion process within the flame itself. These agents are effective on small spill fires and on

fire involving jetting or falling fuels. However, caution should be exercised when extinguishing

pressure fires to ensure that the remaining hazard is not greater than the original fire. Dry

chemicals are nonconductive agents suitable for fires involving energized electrical equipment

with recognition that the particulate residue may be corrosive and certainly requires cleanup.

Rapid fire control and flame reduction may also be achieved by using multipurpose (ABC) dry

chemical on combustible materials such as wood and paper; however, an additional quenching

agent such as water must often be used to extinguish the remaining embers.

Dry chemical extinguishing agents have proven to be effective when used simultaneously with

water fog without interfering with the effectiveness of the chemical. The water fog will quench

embers, cool hot surfaces and reduce flame size making the fire easier to extinguish with the dry

chemical. This cooling effect is particularly important if a fire has been burning for a significant

period, since there is a high chance of reflash if fuels contact heated metal. For further

information, see API Publication 2021, NFPA 10 and 17

Dry Chemical Extinguishers and Equipment

Dry chemical extinguishers are available in hand-carried, wheeled, truck-mounted, and

stationary units. They have capacities ranging from 1.5 pounds (0.7 kg) to 3,000 pounds (1365

kg) of chemical per unit. Multiple units can provide higher capacities if required for special

installations. Stationary units can be piped for manual, semiautomatic, or automatic control.

NFPA 17 provides information concerning installation of dry chemical extinguishing systems.

Portable hand extinguishers containing 30 pounds (13.65kg) or less of dry chemical are

recommended for use as incipient fire fighting equipment for small fires. Several hand

extinguishers may be used simultaneously for extinguishing larger fires. Reserve, or secondary,

protection can be provided by wheeled or stationary extinguishers with capacities up to 350

pounds (160 kg). Some operators prefer to use several hand units simultaneously from different

angles to provide coverage of the fire and reduce the potential for reignition. This multiple

application may be supplemented by properly directed, waterfog streams.

Portable extinguishers should be placed in locations which are safely accessible in the event of a

fire. Whenever an extinguisher is used, it should be replaced and removed for inspection and

recharging. Some operators seal an extinguisher or cabinet so that it may be monitored more

readily. Other operators place the extinguisher in an expendable plastic bag that serves the same

33

purpose while keeping the extinguisher clean and preventing atmospheric corrosion. Reference

should be made to the manufacturer’s recommendations for inspection, servicing, and repair; and

to NFPA 10.Large chemical quantities delivered by hose line discharge can be supplied by

stationary or mobile extinguishers having capacities of 500 pounds (225 kg), 1000 pounds (455

kg), and 2000 pounds (909 kg). Several hose line stations may be equipped with these

extinguishers to protect a given area.

Extinguishers designed for stationary use may also be mounted on vehicles for the protection of

larger subdivided areas. Manufacturers have made available specially-designed fire trucks with

dry chemical capacities to 3000 pounds (1365 kg). The chemical may be discharged through

hose lines, or through high-capacity turret nozzles that have a protection range of approximately

100 feet (30 meters). These fire trucks may also be equipped with supplementary water

extinguishing equipment. However, when using large wheeled units, fire visibility may be lost

because of the dust cloud.

COMBINED AGENTS

Since aqueous film-forming foam (AFFF) can be combined with dry chemicals, systems have

been developed for simultaneous or alternate application of these foams and dry chemicals. Refer

to NFPA 11 for system design criteria.

HALON EXTINGUISHING AGENTS

Halon extinguishing agents, such as 1211, 1301, and 2402, are no longer recommended for use

in new installations in accordance with the Montreal Protocol, due to concerns regarding effects

on the earth’s ozone layer. Acceptable Halon replacement agents are currently available; see

NFPA 2001, Clean Agent Fire Extinguishing Systems. For maintenance of existing Halon

systems, refer to NFPA 12A for Halon 1301; and NFPA 12B for Halon 1211 systems.

CARBON DIOXIDE

An inert gas such as carbon dioxide (C02), discharged into a closed room or into enclosed

spaces, can be effective in extinguishing fires in petroleum pump rooms, electrical installations,

and for some special machinery or laboratory apparatus. Nevertheless, the asphyxiation hazard to

personnel must be recognized and addressed in the use of an inert gas system. Due to static

electricity hazard, carbon dioxide systems should not be used to inert a flammable atmosphere to

prevent ignition. See NFPA 12 for additional information.

STEAM SMOTHERING

The general use of steam as an extinguishing agent can be ineffective. A substantial delay will

occur before sufficient air is displaced or diluted to render the atmosphere incapable of

supporting combustion. Steam is effective in special situations:

a. Smothering steam in furnace fire boxes and header boxes.

34

b. Steam rings on equipment flanges.

c. Steam rings on hot-tap equipment. Steam should not be injected into large vapor spaces such

as cone-roof tanks containing flammable mixtures; static electricity generation from such

application is believed to have been the source of ignition for fires in the past.

35

Hazards of Delayed Coker Unit (DCU) Operations

Process Description

Each DCU module contains a fired heater, two (in some cases three) coking drums, and a

fractionation tower.

In delayed coking, the feed material is typically the residuum from vacuum distillation

towers and frequently includes other heavy oils. The feed is heated by a fired heater (furnace)

as it is sent to one of the coke drums. The feed arrives at the coke drum with a temperature

ranging from 870 to 910°F. Typical drum overhead pressure ranges from 15 to 35 psig. Under

these conditions, cracking proceeds and lighter fractions produced are sent to a fractionation

tower where they are separated into gas, gasoline, and other higher value liquid products. A solid

residuum of coke is also produced and remains within the drum.

After the coke has reached a predetermined level within the ―on oil‖ drum, the feed is diverted to

the second coke drum. This use of multiple coke drums enables the refinery to operate the fired

heater and fractionation tower continuously. Once the feed has been diverted, the original drum

is isolated from the process flow and is referred to as the ―off oil‖ drum. Steam is introduced to

strip out any remaining oil, and the drum is cooled (quenched) with water, drained, and opened

(unheaded) in preparation for decoking. Decoking involves using high pressure water jets from a

rotating cutter to fracture the coke bed and allow it to fall into the receiving area below. Once it

is decoked, the ―off oil‖ drum is closed (re-headed), purged of air, leak tested, warmed-up, and

placed on stand-by, ready to repeat the cycle. Drum switching frequency ranges from 10 to 24

hours. DCU filling and decoking operations are illustrated in Figure. Equipment used in coke

cutting (hydro blasting) operations.

SPECIFIC OPERATION HAZARDS

Coke Drum Switching

Most DCU operations consist of several DCU modules, each typically alternating between two

coke drums in the coking/decoking sequence. Some DCU modules include a third drum in this

sequence. Each drum includes a set of valving, and each module includes a separate set of

valving. Differences in valving among drums and among modules may be difficult to

distinguish and can lead to unintended drum inlet or outlet stream routing. Similarly, valve

control stations, for remotely activated valves, may not always clearly identify the operating

status of different drums and modules. Activating the wrong valve because of mistakes in

identifying the operational status of different drums and modules has led to serious incidents.

36

Coke Drum Head Removal

Conditions within the drum, during and after charging, can be unpredictable. Under abnormal

conditions, workers can be exposed to the release of hot water, steam and coke, toxic fumes, and

physical hazards during removal of the top and bottom drum heads. The most frequent and/or

severe hazards associated with this operation are described below:

Geysers/eruptions - Under abnormal situations, such as feed interruption or anomalous short-

circuiting during steaming or quenching, hot spots can persist in the drum. Steam, followed by

water, introduced to the coke drum in preparation for head removal can follow established

channels rather than permeate throughout the coke mass. Because coke is an excellent

insulator, this can leave isolated hot areas within the coke. Although infrequent, if the coke

within the drum is improperly drained and the coke bed shifts or partially collapses, residual

water can contact the isolated pockets of hot coke, resulting in a geyser of steam, hot water, coke

particles, and hydrocarbon from either or both drum openings after the heads have been

removed.

Hot tar ball ejection - Feed interruption and steam or quenching water short-circuiting can also

cause ―hot tar balls,‖ a mass of hot (over 800°F) tar-like material, to form in the drum. Under

certain circumstances, these tar balls can be rapidly ejected from the bottom head opening.

Un drained water release – Un drained hot water can be released during bottom head removal,

creating a scalding hazard. Shot coke avalanche - Sometimes, the coke forms into a multitude of

individual, various sized, spherical shaped chunks known as ―shot coke,‖ rather than a single

large mass. In this situation, the drum contents are flowable and may dump from the drum when

the bottom head is removed, creating an avalanche of shot coke.

Platform removal/falling hazard - Some DCUs require the removal of platform sections to

accommodate unheading the bottom of the drum. This can introduce a falling hazard.

Coke Cutting (Hydro blasting Operation) Coke-cutting or -hydro blasting involves lowering

from an overhead gantry a rotating cutter that uses high pressure (2000 to 5000 psig) water jets.

The cutter is first set to drill a bore hole through the coke bed. It is then reset to cut the coke

away from the drum interior walls. Workers around the gantry and top head can be exposed to

serious physical hazards, and serious incidents have occurred in connection with hydro blasting

operations. Some of the most frequent and/or severe hazards are described below:

If the system is not shut off before the cutting nozzle is raised out of the top drum

opening, a high pressure water jet can be exposed and seriously injure, even dismember a

nearby worker.

37

Fugitive mists and vapors from the cutting and the quench water can contain

contaminants that pose a health hazard.

The water hose can burst while under high pressure, resulting in whipping action that

can seriously injure nearby workers.

The wire rope supporting the drill stem and water hose can fail (part), allowing the drill

stem, water hose, and wire rope to fall onto work areas.

Gantry damage can occur, exposing workers to falling structural members and

equipment.

38

FLOW DIAGRAM OF PROCESS AND PRODUCTION UNITS

39

FISHBONE DIAGRAM FOR CAUSES OF ACCIDENT

40

FISHBONE DIAGRAM OF ACCIDENT PREVENTION

41

FOAM CHAMBER FOR A CONICAL ROOF APPLICATION

BLOCK DIAGRAM OF AUTOMATIC ,MEDIUM & HIGH EXPANSION FOAM SYSTEM

42

FOAM CHAMBER AND DAM FOR A FLOATING ROOF TANK

43

FIRE CONTROL & EXTINGUISHING EQUIPMENT

SPRINKLER SYSTEMS

FIRE WATER DELUGE SYSTEMS

EMERGENCY SHUTDOWN

MANUAL ALARM PIONTS

DISTIBUTED CONTROL

SYSTEMS

SUPERVISORY CONTROL

44

PROCESS SEQUENCE OF DCU OPERATION

45

DCU COKE DRUMS & HYDROBLAST SYSTEMS

46

DRY CHEMICAL POWDER SYSTEM

47

WET PIPE SPRINKLER SYSTEM

CLEAN AGENT SYSTEM

48

49

BACK IN TECHNIQUE

BOUNCE OFF TECHNIQUE

50

FOAM TETRAHEDRAN

FOAM BEHAVIOUR ON FIRE

51

NEVER PLUNGE TECHNIQUE

RAIN DOWN TECHNIQUE

52

REFERENCES

1. Synthetic fuels hand book by james G.speight.

2. Krick & Orthmer Encyclopedia of Industrial Chemistry.

3. Guidelines for fire protection in chemical, hydrocarbon & petrochemical processing facilities.

(CCPS).

4. Guidelines for risk based process safety.

5. Chemical process safety by Daniel A.Crow.

7. Chemical process safety by Roy E.Sanders.

8. Handbook of Hazardous Materials by Hildegarde L.A.Sacarello.

9. Handbook of Chemical Technology & Pollution Control by Martin B. Hocking.

10. www.hse.gov.uk

11. www.csb.gov

12. Plant Engineers Handbook.

13. www.api.org

14) NFPA 11

15) NFPA 24

53