chemical sefety

8/8/2019 Chemical Sefety

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IntroductionSafety is freedom from danger or risk and isgenerally practised by all human beings as anatural instinct. However, we see so many unsafeacts being done everyday and accidents taking

place causing injury, death, loss of property ordamage to environment. The reason for unsafe

acts can be either lack of awareness of the dangerand its consequences, or lack of skill for doingthe job or not following the laid down procedure.There is need, therefore, for bringing about

awareness, imparting proper training and

regularly reminding ourselves of the importanceof safety in carrying out our job, particularly ahazardous job. The type of programme that weare going through to-day is one effort towardsthat objective.

There was a time when safety in industrialoperations meant safe handling of electrical andmechanical machines and appliances. However

with the advent of chemical industry whichinvolves handling of various hazardous chemicals

in large quantities the risks associated with

handling of such chemicals have been a major

8Th Endowment Lecture on Chemical Process Safety

R. K. Garg

Retired, Chairman & Managing Director, Indian Rare Earths Ltd.

Table 1: Chemical Accidents World

YEAR PLACE PLANT/

TRANSPORT

CHEMCIAL EVENT DEATHS /

INJURIES

1917 LONDON, UK MUNITIONS TNT HIGH

EXPLOSIVE

69 DEATHS

426 INJURIES

1921 OPPAU, GERMANY CHEMICAL

WORKS

AMMONIUM

NITRATE

NITRATE

EXPLOSION

561 DEATHS

1928 HAMBURG,

GERMANY

STORAGE TANK PHOSGENE TOXIC

RELEASE

10 DEATHS

1933 NEUNKIR,

GERMANY

Gasholder TOWN GAS EXPLOSION 65 DEATHS

100 INJURIES1942 TESSENDERLOO

NELGIUM

CHEMICAL

WORKS

AMMONIUM

NITRATE

NITRATE

EXPLOSION

100 DEATHS

1948 LUDWIGSHAFEN,

FRG

RAIL TANK CAR DIMETHYL

ETHER

VAPOUR

EXPLOSION

207DEATHS

3818 INJURIES

1959 GEORGIA, USA RAIL TANK CAR LPG VAPOUR

EXPLOSION

23 DEATHS

1974 FLIXBOROUGH, UK CAPROLACTUM CYCLO

HEXANE

VAPOUR

EXPLOSION

28 DEATHS

104 INJURIES

1976 SEVESO, ITALY REACTOR TCDD INTERNAL

EXPLOSION

Toxic Release

EXTENSIVE

CONTAMINA

-TION

1984 MEXICO CITY TERMINAL LPG BLEVE, FIRE 650 DEATHS

6400 INJURIES

1988 PIPER ALPHA,

North Sea

OFFSHORE OIL HYDROCARBO

N

VAPOUR

EXPLOSION

167 DEATHS

1989 PASADENA USA POLYETHYLENE ISOBUTANE VAPOUR

EXPLOSION

235 DEATHS

103 INJURIES

1990 BANGKOK,

THAILAND

ROAD TANKER LPG VAPOUR

FIRE

68 DEATHS

103 INJURIES

1994 DRONKA, EGYPT FUEL STORAGE AVITATION,

DIESEL

FIRE 410 DEATHS


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concern. If we have a look at the accident history

of chemical industry world over, we find a

number of major accidents, which caused damageto health, life and property. Some of the major

accidents, which are tabulated in Table-1 and 2catalysed the need for analysing and improving

safety systems and procedures in the handlingand processing of chemicals. The Bhopal accident

of 1984, involving a pesticide intermediate, is evennow mentioned in all chemical process safety

forums. It was one of the worst accidents in the

history of chemical industry, causing a large

number of deaths and injuries.

The hazards in the handling or processing ofchemicals arise due to:

i) their inherent properties like flammability,explosivity, toxicity or corrosivity,

ii) reactions between them which may go out ofcontrol and release large amount of energy

leading to mechanical failure and resultingin release of the hazardous material which

may cause fire, explosion or toxic dispersionin the environment.

The key element in ensuring safety in handlingchemicals is, therefore, containment integrity

during storage and reactions.

Safety in Indian Chemical Industry

As compared to other industrialised countries thegrowth of chemical industry in India has beenmore recent. Safety in the industry became amatter of great concern for everybody including

industry owners, professionals, government andthe public especially after the Bhopal accident of

1984. After this the Factories Act was amendedin 1987 to include safety in handling and use ofchemicals as an important section. TheManufacture, Storage, and Import of Hazardous

Chemicals (MSIHC) rules were also framed in

Table 2: Chemical Accidents IndiaYEAR PLACE PLANT/

TRANSPORT

CHEMCIAL EVENT DEATHS /

INJURIES

1974 ALLAHABAD RAIL TRANSPORT FIRE WORKS EXPLOSION 42 DEATHS

1980 MANDIRASO

D

CHEMICAL PLANT

STORE

EXPLOSIVE EXPLOSION 50 DEATHS

1984 BHOPAL STORAGE TANK METHYLISOCYANATE

TOXICRELEASE

3000 DEATHS

1985 MUMBAI CAUSTIC

CHLORINE PLANT

CHLORINE TOXIC

RELEASE

1 DEATH

150 INJURIES

1985 NEW DELHI CAUSTIC

CHLORINE PLANT

OLEUM TOXIC

RELEASE

1 DEATH

150 INJURIES

1987 BHOPAL PLANT AMMONIA TOXIC

RELEASE

20,000

EVACUATIO

N

1990 NAGOTHANE ETHYLENE PLANT ETHANE,

PROPANE

VAPOUR

CLOUD

EXPLOSION

31 DEATHS

1991 KOLKATA LEAKAGE FROM

PIPELINE

CHLORINE TOXIC

RELEASE

200 DEATHS

1992 NEW DELHI CHEMICAL

WAREHOUSE

HAZARDOUS

CHEMICAL

EXPLOSION 43 DEATHS

20 INJURIES

1994 NEW DELHI STORE HAZARDOUS

CHEMICAL

FIRE 500 INJURY

1995 CHENNAI TRANSPORT

ACCIDENT

FUEL FIRE 100 DEATHS

23 INJURIES

1997 34 DEATHS

31 INJURIES


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1989 under the Environment Protection Act, 1986.

Immediately after the Bhopal accident in 1984, a

Committee was appointed by the Maharashtra

Government to evaluate the safety and

environment status of process industries in the

state. The Committee visited about 50 industries

and prepared a report pointing out the

deficiencies and the remedial steps to be taken.

Mr. P.K. Ghosh who assisted the Committee at

my request, had perhaps the maximum

contribution to the Committees work although

as Chairman I got the maximum credit so much

so that the Committee is known by my name.

After that I have had the opportunity of

continuing my association with the chemical and

allied industries not only in Maharashtra but alsoin other parts of the country as well. On the basis

of my observation I can confidently say that the

attitude of industry in respect of safety and

environment protection and the ground situation

are vastly improved. This is not to say that all is

well and one can relax. The target of zero accident

rate in all process units is still a long way to

achieve. Only a few industries have been able toachieve a consistently accident free operation fora number of years. I am happy to mention thatsome industrial units and power plants under the

Department of Atomic Energy come under thiscategory and have been winning safety awards

of the National Safety Council and DirectorateGeneral Factories Advice Services and LabourInstitute.

If a comparison of the safety record (human

safety) of chemical industry vis a vis otherindustrial sectors is made (Table 3) it is observedthat the chemical industry finds a place aroundthe middle. In view of the higher awareness forsafety and the fact that the industry (particularly

the large and medium units) is run by wellqualified persons, the accident rate should bemuch lower and this industry should be the rolemodel. For this to happen industry managers

have to recognise that simply reacting to accidentsand then determining where additional safety

systems are needed cannot be the strategy, sincethe potential effects of accidents can be very

Table 3: Incidence Rate (Per 100 Workers Employed) Industry Wise

Source Labour Bureau Pocket Book of Labour Statistics

1995 2000SL.N

O

INDUSTRY

FATAL NON-

FATAL

FATAL NON-

FATAL

1. ALL TEXTILES 0.12 36.44 0.04 9.63

2. WOOD & WOOD

PRODUCTS

0.14 4.87 0.11 2.88

3. PAPER & PAPER

PRODUCTS

0.33 13.61 0.11 2.88

4. CHEMICALS &

CHEMICAL PRODUCTS

0.26 8.07 0.11 1.76

5. NON-METALLIC

MINERAL PRODUCTS

0.22 12.46 0.13 3.04

6. BASIC METALS 0.40 19.11 0.17 5.05

7. FABRICATED METAAL

PRODUCTS

0.22 13.23 0.05 2.71

8. MACHIENRY &

EQUIPMENT

0.07 9.09 0.04 2.77

9. MOTOR VEHICLES,

TRAILERS

0.15 16.54 0.03 0.69

10. ELECTRICITY, GAS &

STEAM

0.42 12.57 0.05 1.29


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damaging. A proactive approach to safety isrequired. Accidents, apart from causing human

injuries, fatalities, economic loss or damage toenvironment, have a long term impact of affectingthe image of the concerned organisation as well

as the industry as a whole. Our economic activity

and life style are so much dependent on productsof chemical process industries which encompasspetroleum refining, production of petrochemicals,fertilisers, pesticides, drugs and pharmaceuticals,health care products, nuclear material processing,

to name a few. It is, therefore, incumbent on all ofus associated with these industries to strive to

make them accident free.

Planning For Safety

When we talk of process safety it is implied that

it includes:

i) Safety of personnel working in the plant

ii) Safety of equipment and structures

iii) Safety of environment and the persons

outside the plant

The planning for safety has to cover all stages of

a facility starting from conceptual design tositing, detailed design, construction, operation

and maintenance, temporary shutdown and final

dismantling/decommissioning. To this shouldalso be added transportation of hazardous

materials. Temporary shutdown phase has been

included with the emphasis that it is often a

neglected phase, but a number of accidents with

serious consequences including the accident atBhopal occurred during this phase. Another

accident occurred in Mumbai in a chlor alkaliplant a few months later after the Bhopal

accident in a shutdown plant. In order toeliminate/reduce the chances of accidents and

to ensure safety in a process, it is necessary toidentify and evaluate the hazards associated

with the process. Thus, the safety plan for aprocess involves the following two step

approach:

i) Identification and evaluation of the hazardsin the process

ii) Providing equipment, systems and

procedures commensurate with the nature

and magnitude of the risk.

Before proceeding further let me say a few words

about hazard and risk which are often used

interchangeably. There is a subtle differencebetween the two. Hazard has been defined as a

characteristic of the system/plant/process that

represents a potential for an accident. It is the

combination of a hazardous material and the

operating environment such that certain

unplanned events could result in an accident.

Another way it has been defined as a chemical

or physical condition that has the potential for

causing damage to people, property or

environment

Where as Risk is a measure of potential human

injury, environmental damage or economic loss

in terms of both the incident likelihood and the

magnitude of the loss or injury, if it occurs.

Hazard Evaluation Techniques

Coming back to hazard identification and

evaluation as the first step to safety planning a

number of procedures are in use, viz

Preliminary Hazard Analysis

Process/Systems check lists

Relative Ranking Dow and Mond Hazard

Indices

Safety Review

What If Analysis

Hazard and Operability Studies (HAZOP)

Failure Mode, Effect & Criticality Analysis

(FMECA)

Fault Tree Analysis

Event Tree AnalysisCause-Consequence Analysis

Human Error Analysis

One or more of these procedures can be used

depending upon the purpose, the stage of the

facility (conceptual, design, construction etc) and

the available skill. For hazard evaluation at


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What if analysis is not a very structured procedureand its purpose is to consider the results of

unexpected and unintended events that wouldproduce an adverse consequence. The methodinvolves examination of possible deviations and

uses questions such as

What if the wrong material is delivered?

What if pump A stops running during start up?

What if operator opens valve B in place of A?

Safety review is a tool for ensuring that the plant

and operating and maintenance procedures matchthe design intent and standards. The review team

looks at applicable codes and standards; detailedplant description including piping adinstrumentation drawings and flow sheets;

procedures for start-up and shutdown, normaloperation and emergencies; personnel injuryreports; hazardous incident reports; maintenance

records such as critical instruments checks, pressurerelief valve tests, pressure vessel inspections; processmaterial characteristics (i.e. toxicity, reactivity) etcand carries out a detailed inspection of the plant.

Quantitative risk assessment (QRA) Qualitative

information on the failure of component or system

and its likelihood and consequences, is generally

sufficient to decide on making safetyimprovements. However, for deciding on major

safety modifications involving substantial

expenditure, quantitative cost/benefit

information is sometime required by themanagement. QRA is expected to provide

information on the expected frequency and theconsequences of accidents that could occur. It is

based on available information, from pastexperience, on component/system failure rates.

More over What is an acceptable risk is a

difficult question to answer and is highlysubjective. It is also not easy to estimate long term

risk to workers or the public from chronic

exposures to potentially harmful substances oractivities. In view of this and the uncertainty in

the results, QRA can only be a complimentary toolto other safety assurance methods and can not by

itself be the basis for decision making.

For getting an estimate of the impact of a toxic

release or of flammable material release and itsignition, readymade models are available and arebeing used. They can be a good guide to providingdistances between vulnerable sections of the plant

and of the plant from the public domain.

Safety Management

An effective safety management system has to

ensure that safety is the overriding considerationat all stages of the plant, starting from site

selection to plant design, layout, equipmentselection, fabrication, construction,commissioning, operation and maintenance and

shutdown. Safety management calls for an in-depth knowledge of the process, all the plantcomponents, systems and procedures. As a

general guide it is based on the followinginformation about the plant and reviewingadequacy of the various safety systems in the light

of the hazard evaluation study.

i) Process technical data: It includes chemicaldata in respect of raw materials, intermediateproducts and products (from Material Safety

Data Sheet (MSDS) or other literature);reaction chemistry, reaction kinetic data,

temperature and pressure condition of the

reactions, operating limits, controlphilosophy, material and energy balances,

waste generated, process flow diagram withflow rates, piping and instrumentationdrawings.

ii) Plot plan: It should show major process

equipment and storage in the site, indicating

special design considerations such asseparation distances, underground piping

and services, zones along with electricalclassifications.

iii) Equipment specification: Specifications forprocess equipment such as pumps,

compressors, tanks, vessels, heat exchangersetc. showing material of construction, design

process conditions, protection systems (reliefvalves, fire suppression systems, scrubbers,condensers) and mechanical details with


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design codes and standards used. Pipingspecifications include the materials, type and

size, fittings, valves, gasket materials for thechemicals expected to be handled.Information on hydrostatic test reports,

manufacturing inspection reports, weld

radiographs, stress relieving records etc.should be available. For highly toxic andhazardous materials or for meeting specificprocess requirements, special not socommonly used equipment/systems may be

required, e.g. diaphragm type pumps andcompressors and bellow sealed valves for

zero gland leakage, all welded pipelineswithout jointing, non-lubricated machinery(for oxygen service), inerting with nitrogenfor exclusion of oxygen, exclusion of water,

protection for shock sensitive materials, andagainst electro-static charge generation.

iv) Instruments: A list of all the instruments in theprocess which are important for maintainingprocess safety should be avaiable. Theyinclude sensors (for temperature, presure,flow, level etc.), transmitters, controllers,control valves, pressure reducers etc. alongwith specification sheets, design conditions,material of construction (for components incontact with process fluids). Instruments formonitoring of emission from vents/stacks,work environment, and ambient airmonitoring should also be available.Arrangements for calibration of instrumentsare also to be provided. Many of todays largeand medium size plants are controlled andmaintained by programmable controllers anda computer. The specifications of the hardwaresystem including UPS and the softwaredocumentation should be available and shouldbe kept securely under management control.

v) Operation procedures: An operation manualgiving the detailed procedure for day to dayoperation of the plant should be available tothe operators. It should clearly provideinstructions for conducting all the activitiesin each process step in a safe manner andshould cover all phases viz. Start-up, normal

operation, emergency operations (including

emergency shutdown) and normalshutdown. It should give the operating limits,the consequences of deviations, steps to betaken to correct deviation and safety systems

in place to handle deviation. Safety related

information like hazardous properties ofchemicals used, special instructions, if any,

in inventory control, and quality control

procedures should be included. The

operating manual should be kept upto-date

and the procedure for changes to be made inthe manual should be well-defined.

vi) Maintenance procedures: They should be

well documented and a system of keeping

records of all maintenance jobs should be in

place. Safety instructions for on-linemaintenance and for removal of the

equipment for maintenance, e.g. draining andflushing the system to completely remove all

hazardous material before taking up anymaintenance job, use of personal protective

equipment (PPE) should be provided. Many

serious accidents involving fire as well as

toxic release have taken place during

maintenance due to hazardous materials notfully removed from the system.

vii) Training: Initial as well as refresher trainingof the operational and maintenance staff is

the most important factor, which can

contribute to process plant safety. It is

gratifying to note that a lot of emphasis is

given to this aspect in the DAE units and incritical areas there is even a licensing

requirement. However in many otherindustries training needs greater attention.

viii)Accident investigation: A system of accident

reporting and analysis forms anotherimportant part of safety management. Basedon these investigations safety systems can be

further strengthened. Efforts should also be

made to get reports of near-miss incidents so

that preventive steps can be taken and further

accidents can be avoided. Some plants have

already introduced this practice.


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ix) Regulatory aspects: In addition to theFactories Act 1948 (amended in 1987) which

is applicable to all factories there are rulesmade in respect of plants handling hazardouschemicals, under the Environment Protection

Act, 1986. These include:

a) Notification of the Ministry of

Environment and Forests, 1994 forcarrying out an Environmental Impactassessment (EIA) study before setting upa new plant or for expansion of existing

units of certain size. The procedure forenvironmental clearance by the Ministry

of Environment is under review.

b) Manufacture, storage and import ofhazardous chemicals (MSIHC) Rules,

1989.

c) Hazardous waste (Management and

Handling) Rules, 1989

d) Public liability insurance Rules, 1991

e) Emission standards for gaseous, liquid

effluents prescribed by the CentralPollution Control Board and the StatePollution Control Boards.

The MSIHC Rules call for preparation of Safety

Report, Safety Audit and preparation of On-siteand Off-site emergency plans and conductingdrills periodically.

All the above regulations are applicable to DAE

installations also.

Thus ensuring safety and environment protectionin a process plant is not only required from socio-economic considerations and is voluntary but is

also an obligation under the laws of the land.

Conclusion

In conclusion, I would again state my view of the

status of safety in the Indian chemical industry over

the years. Along with the growth of the industry,

there has been considerable improvement in the

awareness, attitude and performance of the

chemical plants in respect of safety. Hopefully this

trend will continue. The importance of safety can

be gauged from the fact that even financial

institutions critically examine the safety andenvironmental protection systems of a project before

providing financial support. I would also like to

make one more comment, which the audience here

will be happy to hear. I feel that now the safety

professionals have a greater respectability than what

they used to enjoy earlier. The Department of

Atomic Energy has been an exception in that safety

activity has always been considered as important

as any other. This should serve as a motivation to

safety professionals in other industries to put in

more efforts to reach the goal set by a safety expertthat every one in the plant from top to the bottom

becomes a safety officer.

chemical sefety

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