Jones D.S.J., Pujado P.R. Handbook of Petroleum Processing

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694 CHAPTER 15

Skin contact. Causes irritation to skin. Symptoms include redness, itching, and pain.

May be absorbed through the skin with possible systemic effects.

Eye contact. Vapors are irritating to the eyes. Splashes can produce painful irritation

and eye damage.

Chronic exposure. Prolonged skin contact may defat the skin and produce dermatitis.

Chronic exposure may cause central nervous system effects.

Aggravation of pre-existing conditions. Persons with pre-existing skin disorders or

eye problems or impaired respiratory function may be more susceptible to the effects

of the substance.

First aid and personal protection

Inhalation. Remove to fresh air. If not breathing, give artiﬁcial respiration. If breath-

ing is difﬁcult, give oxygen. Get medical attention.

Ingestion. Aspiration hazard. If swallowed, vomiting may occur spontaneously, but

DO NOT INDUCE. If vomiting occurs, keep head below hips to prevent aspiration

into lungs. Never give anything by mouth to an unconscious person. Call a physician

immediately.

Skin contact. Immediately ﬂush skin with plenty of soap and water for at least 15 min

while removing contaminated clothing and shoes. Get medical attention. Wash cloth-

ing before reuse. Thoroughly clean shoes before reuse.

Eye contact. Immediately ﬂush eyes with plenty of water for at least 15 min, lifting

upper and lower eyelids occasionally. Get medical attention.

Clothing and protective equipment

Airborne exposure limits.

Permissible exposure limit (PEL): 200 ppm (TWA)

Threshold limit value (TLV): 200 ppm (TWA), 300 ppm (STEL)

Ventilation system. A system of local and/or general exhaust is recommended to keep

employee exposures below the Airborne Exposure Limits. Local exhaust ventilation

is generally preferred because it can control the emissions of the contaminant at its

source, preventing dispersion of it into the general work area.

Personal respirators. If the exposure limit is exceeded and engineering controls are

not feasible, a full-face piece respirator with organic vapor cartridge may be worn

HANDLING HAZARDOUS MATERIALS AND SAFETY 695

up to 50 times the exposure limit or the maximum use concentration speciﬁed by

the appropriate regulatory agency or respirator supplier, whichever is lowest. For

emergencies or instances where the exposure levels are not known, use a full-face

piece positive-pressure, air-supplied respirator. WARNING: Air purifying respirators

do not protect workers in oxygen-deﬁcient atmospheres.

Skin protection. Wear impervious protective clothing, including boots, gloves, lab

coat, apron or coveralls, as appropriate, to prevent skin contact. Butyl rubber is a

suitable material for personal protective equipment.

Eye protection. Use chemical safety goggles and/or a full face shield where splashing

is possible. Maintain eye wash fountain and quick-drench facilities in work area.

Fire prevention and ﬁghting

Fire

Flash point: −9

◦

C (16

◦

F) CC

Auto-ignition temperature: 404

◦

C (759

◦

Flammable limits in air % by volume:

lel: 1.4; uel: 11.4

Extremely Flammable.

Explosion. Above ﬂash point, vapor-air mixtures are explosive within ﬂammable

limits noted above. Vapors can ﬂow along surfaces to distant ignition source and ﬂash

back. Contact with strong oxidizers may cause ﬁre. Sealed containers may rupture

when heated. Sensitive to static discharge.

Fire extinguishing media. Dry chemical, foam or carbon dioxide. Water spray may

be used to keep ﬁre exposed containers cool, dilute spills to non ﬂammable mixtures,

protect personnel attempting to stop leak and disperse vapors.

Special information. In the event of a ﬁre, wear full protective clothing and NIOSH-

approved self-contained breathing apparatus with full-face piece operated in the pres-

sure demand or other positive pressure mode. This highly ﬂammable liquid must be

kept from sparks, open ﬂame, hot surfaces, and all sources of heat and ignition.

Accidental release measures. Ventilate area of leak or spill. Remove all sources of

ignition. Wear appropriate personal protective equipment as speciﬁed in Section 8.

Isolate hazard area. Keep unnecessary and unprotected personnel from entering. Con-

tain and recover liquid when possible. Use non-sparking tools and equipment. Collect

liquid in an appropriate container or absorb with an inert material (e.g., vermiculite,

dry sand, earth), and place in a chemical waste container. Do not use combustible

materials, such as saw dust. Do not ﬂush to sewer! If a leak or spill has not ignited,

696 CHAPTER 15

use water spray to disperse the vapors, to protect personnel attempting to stop leak,

and to ﬂush spills away from exposures.

Storage and handling

MEK is usually delivered to a reﬁnery by road or rail truck. It maybe stored in small

bullets or a cone roof tank under an inert gas. The materials of construction is an

appropriate grade of carbon steel.

15.2 Fire prevention and ﬁre ﬁghting

Fire prevention and ﬁre protection is a paramount requisite in the operation of any

hydrocarbon facility. It is more important perhaps in oil reﬁning than any other related

facility because of the relative size of most reﬁneries compared with petrochemical

or chemical facilities. Reﬁnery prevention and protection begins at the early stages

of the reﬁnery design, and engineering. This section of the chapter begins with the

reﬁnery company’s development of the design and engineering speciﬁcation, which is

the document that instructs the Engineering and Construction company in details of

the reﬁnery standards that are to be implemented in the building of the reﬁnery. This

section begins with a list of the items usually contained in the design speciﬁcation.

It continues with more details of those items that pertain to ﬁre prevention and ﬁre

ﬁghting.

The design speciﬁcation

Client companies each have their speciﬁc design speciﬁcation in terms of format and

indeed details of the various speciﬁcations. However most design speciﬁcations will

contain the following subject as a minimum.

The duty speciﬁcation. This is of interest to the design process and mechanical engi-

neer. It states exactly what facilities are to be built and the duty of each item in terms

of throughput and in some cases composition of the various streams. It will also give

speciﬁc detail of the local meteorological data and the parameters to be considered

in economic decisions. The duty speciﬁcation will include the products required and

the composition of the products. It will also give full details of utilities required or

available for the process. In cases of ‘grass roots’facilities the duty speciﬁcation will

cover off sites such as tankage, blending, loading, and unloading facilities, etc.

Mechanical speciﬁcation. This deals with the requirement and standards (including

the codes to be used) the client requires for the equipment that will be installed. The

narrative speciﬁcations that the mechanical engineer will produce based on this, will

HANDLING HAZARDOUS MATERIALS AND SAFETY 697

form part of the package to be used for procuring these items of equipment. These

equipment items will be at least the following:

Pumps

Compressors and Turbines

Heat Exchangers (including Air coolers, double pipe, etc.)

Fired Heaters

Other miscellaneous equipment such as ejectors, blenders, and the like

The electrical and instrument speciﬁcation. This part will set the standards to be used

for all electrical equipment, and the bulk materials associated with the equipment. It

will deal with the ‘Area Classiﬁcation Code’which sets the parameters for equipment

in terms of ﬁre prooﬁng (i.e., whether the item is to be spark proof, etc.) that will be

located in the various areas of the reﬁnery. For instrumentation it speciﬁes the type

of instruments to be used and the basic control and measuring systems to be used.

Piping and layout speciﬁcation. This is usually the largest section of a design speci-

ﬁcation. It will detail the piping codes to be used and the material break points. It will

proceed to establish the criteria for equipment and tankage layout with respect to:

Maintenance accessibility

Fire prevention (e.g., distance of ﬁred heaters from other equipment)

Tank area layout and size of tank bunds

Degree of ﬁre protection piping for plant units and tanks

Under ground piping corrosion protection, etc.

Other sections of the design speciﬁcation. These include detail requirements for ves-

sels, civil, and structural equipment and associated materials.

Fire prevention with respect to equipment design and operation

Fired heaters. Design of ﬁred heaters must incorporate snufﬁng steam facilities for

the ﬁre box. With respect to the maintenance and operation of the heater the following

points should be included into operating procedures:

1. Implement a formal, regularly scheduled preventive maintenance program for

burners and the clean-up of any refractory debris to prevent ﬂame impingement.

2. Introduce a mechanism to monitor and record, more accurately and thoroughly,

tube skin temperature to prevent hot spots.

3. Implement a thorough and complete procedure to deal with hot spots once detected

and reported. This includes the recording of descriptions and locations of any

suspected hot spot detected in a visual inspection.

698 CHAPTER 15

4. Introduce an accurate method to determine the impact on tube life once a hot spot

is detected.

5. The reﬁnery personnel should be trained to recognize and respond to the changes

in metallurgical properties and characteristics demonstrated by different material

in the furnaces that are subjected to high temperature and pressure. Documentation

to be updated to reﬂect this information.

Pressure vessels. These include towers, horizontal and vertical process vessels all of

which must be protected properly with pressure relieving devices (see Chapter 13

for pressure relief facilities). In the design of vessels the correct wall thickness is

based on the API and ASME codes covering the design temperatures and pressures.

Fireprooﬁng of vertical vessel skirts and horizontal vessel supports must be speciﬁed.

In the operation and maintenance of vessels the following items must be included as

standard procedures:

Vessel alarms must be recognized and acted upon.

Action must be taken immediately when excessively high temperatures and high or

low liquid levels are observed.

In the case of a ﬁre on the unit or adjacent unit the towers must be shut down

according to the plant’s emergency shut down procedures.

In the event of an emergency shut down the vessel must be purged free of hydro-

carbons either by steam or inert gas.

No entry or work must be done on the vessel before it is certiﬁed ‘Gas Free’.

All vessels must be inspected before re commissioning after a shut down. The

inspection must ensure that all ﬂanges are secure and the correct gaskets have been

properly installed.

All instruments and relief systems on the vessels must be checked and re-calibrated

on every scheduled or unscheduled shut down of the plant.

All vessels must be pressure tested before commissioning and after any work has

been completed on them.

All drains and vents on the vessel must be checked during scheduled plant

‘turnaround’or un scheduled shut down before re commissioning the vessel.

Heat exchangers and coolers. Shell and tube heat exchangers are designed and fabri-

cated to ASME and TEMA codes. Their shell design follows closely to that of vessels

with respect to design temperatures and pressures. The thickness of tubes and tube

sheets are also calculated using the ASME code. In the case of air coolers the tube

sheets and tubes are also calculated to ASME codes as are the inlet and outlet mani-

folds. Air coolers tubes are usually ﬁnned to enhance the heat exchanger properties of

the units. The operation and maintenance of shell and tube exchangers follow many

of those conditions stated for vessels with respect to ﬁre (or explosion) prevention.

In the case of air coolers however some different rules and procedures apply. For

example a number of air coolers in a reﬁnery are installed above an elevated pipe

HANDLING HAZARDOUS MATERIALS AND SAFETY 699

rack. The pipe rack often runs through the center of a process plant, that is there will

be equipment on both sides of the rack. It is usual for the pipe rack structure to be

encased in a ﬁre proof concrete as a ﬁre prevention measure. This ﬁreprooﬁng should

extend upwards to cover the air cooler structures as well. Fire water and foam sprays

should be installed above the tube nests such as to snuff out any outbreak of tube leaks

and subsequent ﬁres.

Rotary equipment. This group includes all pumps, and compressors. Next to ﬁred

heaters the compressor units, which may include gas driven turbine or turbo ex-

panders, are the items most vulnerable as ﬁre hazards. The reason in this case is the

high pressures of the gas they handle, and this is more so in those units handling

hydrogen. All reciprocal compressors must have pressure relief facilities on the com-

pressor discharge. Most also have an emergency shut down system in the case of

high discharge pressure. Centrifugal compressors and their drivers require a more

sophisticated emergency shut down procedures however. Here critical condition can

arise by poor suction conditions as well as the high-pressure discharge. All centrifugal

compressors therefore require protection against ‘Surge’(or ‘Pumping’) condition.

For example this condition can occur when the compressor suction pressure is so low

that the unit cannot pull any of the feed gas into its impellers. Severe vibration of

the unit follows which, in extreme cases, will cause considerable structural damage

to the unit and even an explosion and ﬁre. Most modern day units do have anti surge

devices, which if properly maintained will close the unit down long before any severe

damage.

Pumps, even those handling high-pressure liqueﬁed petroleum gases are less haz-

ardous. Overheating due to defective seals or packing is the more common hazard

that can cause a ﬁre. Pump cavitating due to NPSH problems being a much lesser

second hazard.

In most present day reﬁneries rotary equipment is installed in the open or in an area

which has only a roof as a cover. This helps a great deal to ﬁght any rotary equipment

ﬁre. Usually the area containing rotary equipment will have both ﬁre water and foam

facilities installed. Close monitoring of the rotary equipment during operation and

regular maintenance of the items are essential for the prevention of ﬁres from these

sources.

Tanks and the tank farm. Tank ﬁres are probably the worse type of ﬁre in a reﬁnery.

This is because tanks hold a high inventory of hydrocarbons. The one thing that lowers

the degree of hazard in the tank farm is that there is usually no direct source of ignition.

There are no ﬁred heaters or large compressor units present in tank farms as a rule.

Fires can occur however from accidents remote from the area such as a ﬁre on a jetty or

a ship nearby. There was a tank farm ﬁre in New York during February 2003, that was

caused by an explosion aboard a barge unloading gasoline at a nearby jetty. Large fuel

700 CHAPTER 15

oil tanks on shore were set ablaze by hot debris from the explosion. Another source

of ﬁre is an explosion in a product loading station while loading a light product such

as gasoline. These explosions are usually caused by static electricity. Most petroleum

companies do have strict procedure in place to prevent such occurrences, but accidents

do happen from time to time.

Middle distillates and fuel oil tanks present the most difﬁcult ﬁres to ﬁght and ex-

tinguish. The large inventory of these tanks and their low volatility but high heating

value can negate for quite a time even using the most up to date foam extinguishing

techniques once the ﬁre has really established itself. The major effort then is to keep

adjacent tanks cool by extensive water spray. Fires on tanks storing lighter liquid

products are a little easier to combat. Foam is used to smother the oil inventory. As

these light products are stored in ﬂoating roof tanks, it provides the means to build

a depth of foam on the roof itself directly on the surface of the liquid if the roof has

been damaged by an earlier explosion. Fire water sprays are installed on LPG spheres

and bullets. In almost every case the initial ﬁre on LPG tankage causes an explosion.

The material remaining can be snuffed out by foam and again the main purpose of the

ﬁre ﬁghting is to activate the ﬁre water sprays on adjacent tanks to keep them cool.

Incidentally all reﬁneries these days have in place ﬁre water and foam spray rings on

all storage tanks (see Chapter 13). Water on its own should only be used to keep the

tank cool from adjacent ﬁre sources. The danger of using water alone to extinguish a

ﬁre is that it may cause the ﬁre to spread by the hydrocarbon continuing to burn on

the surface of the water stream ﬂowing from the tank area.

The design of storage tanks and their installation shall comply with the local Fire

Regulations. In general crude oil and petroleum products with a ﬂash point of <130

◦

shall be stored in ﬂoating roof tanks, or in the case of LPG in bullets or spheres. Middle

distillates and heavier shall be stored in cone roof tanks. Storage tanks, both ﬂoating

roof or cone roof, shall be installed on concrete pads which will be piled if required.

The space between tanks shall not be less than 10 ft (or according to local regulations).

The tank area shall be dyked to hold at least 110% of a single tank inventory. This

dyked or bunded area shall contain adequate drainage leading to the API separator or

holding pond. LPG storage generally does not require a dyked area but both bullets

and spheres shall be installed with proper ﬁreproofed support structures.

Jetty and on shore loading stations. One of the biggest ﬁre hazards in areas of loading

rail/road cars and ship loading is ﬁre by spark caused by static electricity. The proper

earthing of the items being loaded is essential in preventing this ﬁre hazard. The

same applies to the unloading of hydrocarbons such as crude oil feed or other product

streams transferred from other reﬁneries or depots. In small reﬁnery installations the

jetty facilities and the on shore loading islands are protected by an extension of the

off sites ﬁre main and foam systems. In larger reﬁneries the jetty may have its own

ﬁre main using sea water as the main water medium.

HANDLING HAZARDOUS MATERIALS AND SAFETY 701

PIC

To All Monitors

Break Tank

Circ Pump

Figure 15.1. Schematic ﬁre main system.

The ﬁre main

Fire mains are usually designed as a pressurized circulating water system with an at-

mospheric break tank. A schematic sketch of such a system is given as Figure 15.1. The

ﬁre main is maintained at a pressure of around 100 psig by the circulating pump. This

pump is automatically switched on or off to maintain the line pressure when monitors

are opened to deliver the water to ﬁre sources or foam system or for any other appli-

cation for which they are opened to atmosphere. The pump is usually electric motor

driven with a spare which is usually driven by a diesel motor or steam turbine. The spare

pump drive is automatically activated on electrical failure and the inability of the nor-

mal ﬁre circulating pump to maintain line pressure. Make up water to the break tank is

maintained under break tank level control from the reﬁnery’s fresh (or salt water) main.

On smaller reﬁnery facilities and smaller systems, such as a jetty ﬁre main, the system

maybe‘dead ended’. That is the ﬁre water pump would be used only to maintain the

ﬁre main pressure. The water would not be circulated to a break tank. A water source

tank or pit would be used as the ﬁre water source reservoir. In the case of the jetty

ﬁre main usually sea water is used and this would be delivered from a suitable seabed

pit by a vertical pump. Again an electric motor driver would be used for the normal

pump with usually a steam turbine driver for the spare pump.

Fire foam and foam systems

Fire ﬁghting foam is simply a stable mass of small, air-ﬁlled bubbles with a lower

density than oil, gasoline, or water. The foam is made up of three ingredients:

Water;

A foam concentrate; and

Air

The water is mixed with the concentrate (proportioned) to form a foam solution. This

solution is then mixed with air (aspirated) to produce the foam which is very ﬂuid

and ﬂows readily over liquid surfaces.

702 CHAPTER 15

Balanced pressure proportioning is the most common method used for foam system

applications. The foam concentrate pressure is balanced with the water pressure at the

proportioner inlets allowing the proper amount of foam concentrate to be metered into

the water stream. With an aspirating discharge device, foam solution passes through

an oriﬁce, past air inlets, and into an expansion area to produce an expanded foam.

With non-aspirating devices, foam solution passes through the oriﬁce and discharge

outlet where it mixes with air en route to the ﬁre.

Fire ﬁghting foam is used in a variety of applications to extinguish ﬂammable and

combustible liquid ﬁres, to control the release of ﬂammable vapors and to cool fuels

and sources of ignition. Typical foam applications include:

Loading racks

Reﬁneries

Pumping stations

Power plants

Airports

Heliports

Marine applications

Manufacturing plants

Storage tanks

Chemical plants

Flammable liquid storage

Offshore platforms

Aircraft hangars

Crash rescue vehicles

Mining facilities

Warehouses

Hazardous material spill control.

Fire ﬁghting foam agents suppress ﬁre by separating the fuel from the air (oxygen).

Depending upon the type of foam agent, this is done in several ways:

Foam blankets the fuel surface, smothering the ﬁre and separating the ﬂames from

the fuel surface

The fuel is cooled by the water content of the foam

The foam blanket suppresses the release of ﬂammable vapors that can mix with

air

A ﬁlm forming foam (AFFF) agent forms an aqueous ﬁlm on the surface of a

hydrocarbon fuel. An alcohol-resistant concentrate (ARC) will form a polymeric

membrane on a polar solvent fuel. Essentially there are six general types of foam

agents:

HANDLING HAZARDOUS MATERIALS AND SAFETY 703

Class B ﬁre foams

Film-forming foams

Film-forming foams (AFFF) are based on combinations of ﬂuorochemical surfactants,

hydrocarbon surfactants, and solvents. These agents require a very low energy input

to produce a high-quality foam. Consequently, they can be applied through a wide

variety of foam delivery systems. This versatility makes AFFF an obvious choice

for airports, reﬁneries, manufacturing plants, municipal ﬁre departments, and any

other operation involving the transportation, processing, or handling of ﬂammable

liquids. These Foam Forming agents are available as 1% and 3% freeze-protected

concentrates.

Alcohol-resistant concentrates

Alcohol-resistant concentrates are based on AFFF chemistry to which a polymer

has been added. ARCs are the most versatile of the foam agents in that they are

effective on ﬁres involving polar solvents like methanol as well as hydrocarbon fuels

like gasoline. When used on a polar solvent type fuel, the ARC concentrate forms a

polymeric membrane which prevents destruction of the foam blanket. When used on

hydrocarbon fuels, the ARC produces the same rugged aqueous ﬁlm as a standard

AFFF agent. ARCs provide fast ﬂame knockdown and good burn back resistance

when used on both types of fuels.

Protein Foam Concentrates

Protein foam concentrates are recommended for the extinguishment of ﬁres involving

hydrocarbons. They are based on hydrolyzed protein, stabilizers, and preservatives.

Protein foams produce a stable mechanical foam with good expansion properties and

excellent burn back resistance characteristics. Protein foam concentrates are available

in 3% and 6% concentrations.

Fluoroprotein foam concentrates

Fluoroprotein foam concentrates are based on hydrolyzed protein, stabilizers, preser-

vatives, and synthetic ﬂuorocarbon surfactants. When compared to protein foams,

ﬂuoroproteins provide better control and extinguishment, greater ﬂuidity, and supe-

rior resistance to fuel contamination. Fluoroprotein foams are useful for hydrocarbon

vapor suppression and have been recognized as very effective ﬁre suppressing agents

for sub-surface injection into hydrocarbon fuel storage tanks. Fluoroprotein foam is

available in a 3% concentrate.