Southern Luzon State University

College of Engineering
Lucban, Quezon

BHOPAL GAS ACCIDENT

A Case Study Presented to:

Engr. Efren Daya

ME Department Faculty

In partial fulfilment for the second term of the subject

MCE:

Submitted By:

Almirañez, Mary Grace D.

Zarsuelo, Joana Paula

BSME V GO

October 21, 2018

Introduction

Bhopal, the state capital of Madya Pradesh, is geographically at the centre of India. About a
third of its one million inhabitants live in tightly packed, shanty ('kucha') housing in its northern
and central districts. In 1969, Union Carbide (India), a subsidiary of the large American
corporation, set up a pesticide formulation plant on the north edge of the city, originally to
import, mix and package pesticides manufactured in the United States. Ten years later, a 5000
ton methyl isocyanate (MIC) production unit was installed, primarily to manufacture an effective
and inexpensive carbaryl pesticide marketed as 'Sevin'.
MIC is produced by the reaction of (mono) methylamine with phosgene, both of which
were manufactured elsewhere in India and transported in bulk to Bhopal. There it was mixed
with 1-naphthol to produce Sevin for sale throughout the country. MIC is colorless, with a low
boiling point (39 oC) and high vapor pressure; because of its chemical instability it is stored
under refrigeration in dry, stainless steel vessels. At the Bhopal plant, there were several such
storage tanks, one (#610) having an unusually large capacity of 60 tons.

The Gas Disaster

For reasons that remain unclear, the cooling system of tank 610 was not functioning in the
last months of 1984. Late in the evening of December 2nd, it is hypothesized that water (either
through mechanical malfunction or operator error) entered the tank, mixing with the stored MIC.
The result was a violent, exothermic reaction, possibly catalyzed by ferrous corrosion of the
tanks lining. By 01.00 a.m. the next morning, the tank ruptured and over the next few hours
approximately 27 tons of vapor was discharged. There is very little available information on
meteorological conditions that night, but data from the city’s airport suggest an air temperature
of about 10 oC and a slow, northerly wind. At this temperature, the discharged MIC would have
rapidly condensed and fallen groundwards, the plume passing over the northern edge of the city
and towards its centre. An estimated 350 000 people were exposed. Immediate effects, and
those over the following month, included the deaths of approximately 20,000 people, most
attributable to the direct respiratory effects of inhalation.

Series of events that led to the accident

 MIC is stored in three underground tanks made of stainless steel, tank 610, tank 611 and
tank 619. The tanks have to be kept refrigerated so that the temperature of storage is kept
close to 0°C and not above 15°C as given by the safety manual of Union Carbide
Corporation (UCC), but not followed.
 After the tank there is a vent gas scrubber to neutralize the MIC in case of release, by
spraying alkali. Then there is a flare tower to burn the remaining gases going from the
vent gas scrubber, which was also not working
 As per the safety manual the scrubber should be kept in active mode, which means that
the pump has to spray alkali as long as the plant is operating, but a decision was taken to
 keep it in passive mode. Similarly it was decided to shut down the refrigeration plant, to
cut the cost of manufacturing.
 There are two process venting lines RVVH (relief valve and vent header) and PVH
(process vent header). As per the process chart given by Union Carbide Corporation,
RVVH and PVH are not interconnected, but a major decision was taken to carry out a
major plant modification connecting RVVH and PVH before the accident.
 On December 3, the MIC plant supervisor ordered washing of MIC lines assuming that
there was a blockage in the line. At about 9.30 pm on 3 December 1984, the operator
began washing out four lines in the MIC storage area, and all these were connected to the
RVVH. The operation started pumping water under high pressure into the four lines, but
he found that some lines were clogged (blocked).
 Workers stopped washing and reported the problem to the supervisor. The supervisor,
who was transferred from a completely different plant to this unit only two weeks before
the event, just gave instructions for continuation of washing.
 Water enter and started from RVVH to PVH.
 The tank Operator notice a rise of pressure in tank
 First leak of MIC detected.
 Plant supervisor notified about the high pressure and MIC leak.
 Supervisor ordered stopping of washing operations.
 Attempt to start the vent gas scrubber but failed.
 Concrete tanks get very hot.
 MIC vapor escape through the vent line at 33 meters high.
 MIC vapors started affecting people in the vicinity, and a large number of people started
running out of the houses.
 Even after three days, the air in the vicinity of the plant had fairly high levels of cyanide
concentration.

With no doubt, it was a result of poor hazard management, poor safety management practice,
poor use of early warning system, poor perception of the risk involved and so on.
Analysis of failure:

 Poor perception of risk involved.

 Failure to perceive the gravity of the situation after the trigger event.
 Poor safety specification.
 Poor training and use of inexperienced operators.
 Poor emergency procedures and standards.
 Poor maintenance of machines and faulty alarm system.
 No limits for the exposure of chemical and toxic substances was present.

Domino analysis of the accident

In order to promote industrialization and attract large multinational corporations to India,

Union Carbide Corporation was allowed to construct a pesticide manufacturing plant, at Bhopal
in India. Bhopal is the capital of a state, Madhya Pradesh, which is essentially underdeveloped.
The plant was located adjacent to residential areas and was only 3 kilometers from the Bhopal
Railway station and bus stand. Obviously, the plant was located near a thickly populated area
and with that already created a risk that is potentially high.

During operation, theres a lot of Non-functional safety systems that cause the leak and an
uncontrollable exothermic reaction. But because of human negligence on survey warnings
which popped prior to the tragedy, the risk rises that lead to a disaster lead of unleashing MIC to
the atmosphere continuously for about two hours through the vent line. This catastrophic effect
killed more than thousands of people.

Immediate Effects of the Disaster

The timing of the explosion was such that most of those exposed were asleep. Survivors
report being awakened by an acrid ("chili-like") stinging of the eyes and throat. The low boiling
point of MIC caused it to be re-vaporized at body temperature and inhaled deeply into the lungs;
as a result, damage to the bronchial tree was extensive and post-mortem findings in those who
died immediately after the leak reported widespread airway necrosis with pulmonary edema and
hemorrhage.
Until now, clean-up of the site is still pending, those who survived the disaster don’t have alternate
livelihood opportunities and victims are still suffering. The company abandoned the factory site without
cleaning and restoring it to its original state. There are some attemps but the hazard is just so high. The
contaminated land has not been cleaned up and families too poor to move continue to live there. The
livelihoods of more than 30,000 people are affected.

More than 20,000 people still live in the vicinity of the factory and are exposed to toxic chemicals
through groundwater and soil contamination. Health risks and illnesses including cancer, birth defects,
fevers, broils, headaches, nausea, lack of appetite, dizziness, and constant exhaustion continue to
plague a new generation. Tests published in 2002 reported dangerous toxins in the breast milk of
nursing women living near the factory. Recent reports confirm that the contamination is not diminishing
with time. Water from a hand pump in Atal Ayub Nagar, already lethal by 1999, has become seven times
more toxic since then. The rate of birth defects in the contaminated areas is ten times higher than in
the rest of India.

Controls

While natural disasters are largely unpredictable, environmental disasters are caused directly or
indirectly by human behavior. Chemical disasters, like the one in Bhopal, are preventable if risks are
identified and addressed early on.

It will take the combined effort of competent authorities, private sector and society to prevent
tragic environmental events from happening. Some measures include developing policies to ensure that
industries operate in accordance with technical and safety standards and allocating resources for risk
assessment and monitoring.
Because of what happened, there are changes introduced in Factory act to prevent this tragedy
from happenning again. That includes:

Chapter IV-A (Provisions Relating to Hazardous Processes)

Section 41A: Constitution of Site Appraisal Committees

The State Government may, for purposes of advising it to consider applications for grant of permission
for the initial location of a factory involving a hazardous process or for the expansion of any such
factory, appoint a Site Appraisal Committee consisting of Chief Inspector of the State, a representative
of the Central Board for the Prevention and Control of Water Pollution, a representative of the Central
Board for the Prevention and Control of Air Pollution, a representative of the Department of
Environment in the State, a representative of the Meteorological Department of the Government of
India, an expert in the field of occupational health and a representative of the Town Planning
Department of the State Government.

The Site Appraisal Committee shall examine an application for the establishment of a factory involving
hazardous process and make its recommendation to the State Government within a period of ninety
days of the receipt of such application in the prescribed form.

The Site Appraisal Committee shall have power to call for any information from the person making an
application for the establishment or expansion of a factory involving a hazardous process.

Section 41B: Compulsory disclosure of information by the occupier

The occupier of every factory involving a hazardous process shall disclose in the manner prescribed all
information regarding dangers, including health hazards and the measures to overcome such hazards
arising from the exposure to or handling of the materials or substances in the manufacture,
transportation, storage and other processes, to the workers employed in the factory, the Chief
Inspector, the local authority within whose jurisdiction the factory is situate and the general public in
the vicinity.

Every occupier shall, with the approval of the Chief Inspector, draw up an on-site emergency plan and
detailed disaster control measures for his factory and make known to the workers employed therein and
to the general public living in the vicinity of the factory the safety measures required to be taken in the
event of an accident taking place.
The occupier of a factory involving a hazardous process shall, with the previous approval of the Chief
Inspector, lay down measures for the handling, usage, transportation and storage of hazardous
substances inside the factory premises and the disposal of such substances outside the factory premises
and publicize them in the manner prescribed among the workers and the general public living in the
vicinity.

Section 41C: Specific responsibility of the occupier in relation to hazardous processes

Every occupier of a factory involving any hazardous process shall-

(a) maintain accurate and up-to-date health records or, as the case may be, medical records of the
workers in the factory who are exposed to any chemical, toxic or any other harmful substances which
are manufactured, stored, handled or transported and such records shall be accessible to the workers
subject to such conditions as may be prescribed;

(b) Appoint persons who possess qualifications and experience in handling hazardous substances and
are competent to supervise such handling within the factory and to provide at the working place all the
necessary facilities for protecting the workers in the manner prescribed.

Section 41D: Power of Central Government to appoint Inquiry Committee

The Central Government may, in the event of the occurrence of an extraordinary situation involving a
factory engaged in a hazardous process, appoint an Inquiry Committee to inquire into the standards of
health and safety observed in the factory with a view to finding out the causes of any failure or neglect
in the adoption of any measures or standards prescribed for the health and safety of the workers
employed in the factory or the general public affected, or likely to be affected, due to such failure or
neglect and for the prevention and recurrence of such extraordinary situations in future in such factory
or elsewhere.

Section 41E: Emergency standards

Where the Central Government is satisfied that no standards of safety have been prescribed in respect
of a hazardous process or class of hazardous processes, or where the standards so prescribed are
inadequate, it may direct the Director-General of Factory Advice Service and Labor Institute or any
institutions specialized in matters relating to standards of safety in hazardous processes, to lay down
emergency standards for enforcement of suitable standards in respect of such hazardous processes.

Section 41F: Permissible limits of exposure of chemical and toxic substances

The maximum permissible threshold limits of exposure of chemical and toxic substances in
manufacturing processes (whether hazardous or otherwise) in any factory shall be of the value indicated
in the Second Schedule.

Section 41G: Workers' participation in safety management

The occupier shall, in every factory where a hazardous process takes place, or where hazardous
substances are used or handled, set up a Safety Committee consisting of equal number of
representatives of workers and management to promote cooperation between the workers and the
management in maintaining proper safety and health at work and to review periodically the measures
taken in that behalf.
Section 41H: Right of workers to warn about imminent danger

(1) Where the workers employed in any factory engaged in a hazardous process have reasonable
apprehension that there is a likelihood of imminent danger to their lives or health due to any accident,
they may bring the same to the notice of the occupier, agent, manager or any other person who is
incharge of the factory or the process concerned directly or thorough their representatives in the Safety
Committee and simultaneously being the same to the notice of the Inspector.

(2) It shall be the duty of such occupier, agent, manager or the person incharge of the factory or process
to take immediate action if he is satisfied about the existence of such imminent danger and send a
report forthwith of the action taken to the nearest Inspector.

(3) If the occupier, agent, manager or the person incharge referred to in sub-section (2) is not satisfied
about the existence of any such imminent danger as apprehended by the workers, he shall,
nevertheless, refer the matter forthwith to the nearest Inspector whose decision on the question of the
existence of such imminent danger shall be final.

If we had these provisions earlier then:

 Section 41A would have prohibited the establishment of plant and manufacturing of MIC on
such a location, and so we would not have that much high number of victims.
 Section 41B would have make people working there aware of the hazardous process and they
might take some precautions and would be more pro-active.
 Section 41C would have provide a good medical facility to workers of factory as well as it would
also have taken care that the workers are skilled enough to work therein.
 Section 41D would have stopped this accident by taking in regards the early symptoms and small
incidence which took place and govt would have appointed an inquiry committee.
  Section 41F would not have allowed such a large amount (42 tones) of MIC to be stored in the
heart of city.
 Section 41G would have improved the safety measure which would lead to a better supervision
of the factory and workers.
 Section 41H would have alerted the govt and Chief Inspector and the management as workers
have felt some problems and issues several times prior to the accident.

Chemical safety tips that we can learn from the Bhopal gas leak:

1. Act On the Small Problems

It has been documented that there were leaks that occurred leading up to this catastrophe.
However, management failed to take action on these smaller leaks and make corrections in a
timely manner.

A small issue may truly just be an accident, but it also might be an indication of a larger
problem. It’s far better to investigate each small chemical accident and its relation to the system
as a whole to ensure that it is not the sign of something more significant.

2. An Ounce of Prevention Is Better Than a Pound of Cure

Although authorities are not sure of the exact cause of the leak, Union Carbide, the company that
owned the plant, did take fiscal responsibility for the incident. The final settlement, reached in
1989, was for approximately $470 million dollars (with today’s inflation, that sum totals $907
million dollars).

There is some evidence that had the company invested in more safety measures up front, they
might have saved themselves the liability on the backend. It is better to invest in safety
equipment before an accident than to have to pay for negligence after an accident occurs.
In addition, chemical accidents are costly and difficult to clean up. In the case of the Bhopal leak,
the groundwater has been contaminated and the area still poses a health risk for residents in the
community. All of this might have been prevented by investing in the safety.

3. Disclose Chemical Information to First Responders

When the effects of the gas leak began to manifest, many people rushed to the hospital in order
to seek care. Unfortunately, the doctors at the hospitals were unaware of how to properly treat
victims because they did not know the specific chemicals people had been exposed to. This
resulted in even more death and injuries than were perhaps necessary, simply because doctors
could not help the victims.

Laboratories that store potentially dangerous chemicals onsite have a responsibility to

inform first responders regarding the potential dangers of each chemical. The most effective way
to help communicate chemical information with first responders is to use a chemical inventory
management system. The benefits offered by such a system include the ability to produce a
detailed list of the chemicals currently stored on site, as well as information regarding their
location. This can then be shared with first responders to ensure their safety and to empower
them to act appropriately if an accident occurs.

Conclusion:

The tragedy of Bhopal continues to be a warning sign at once ignored and heeded. Bhopal disaster
and its effects serves as a warning for developing countries that led the path through industrialization. If
the Provisions relating to Hazardous Processes would be present at the time of accident and other
safety, health and welfare provisions would be followed, we would never had to face such industrial
disaster. The Bhopal gas leak was a devastating catastrophe. By acting on small problems,
focusing on prevention and supplying first responders with the necessary information, we may be
able to prevent a repeat event from occurring.