Moving on to two other strategy that will be used in safety which are Active and Procedural.
These strategies will encompass of several layers of protection (LOPA). Before proceeding to the
factors and solution to the disaster, we shall see the consequence of the Bhopal incident brought to
the surrounding people.
Bhopal gas tragedy as called by many is a gas leak incident that occurred in India. It is
currently classified as the worst industrial disaster in human kind. It happened on the night of 2
nd
and 3
rd
of December 1984 in the pesticide plant of Union carbide India limited (UCIL) in Bhopal,
Madhya Pradesh, India. This extremely dangerous event happened as it released 40 45 tons of
extremely toxic Methyl Isocyanate (MIC) and other gases in the villages around the plant. It was
estimated that the affected area was about 40 sq km.
In this section it will divided into two strategies where we will discuss the incident if there
are Active and Procedural strategy applied in operating this plant. Starting with the factors of the
incident and next to discuss solution based on Layer of Protection (LOPA) module.
Active is a mainly about control, safety interlock, automatic shutdown systems. It can also
be defined that preventing accidents by using detector or sensor that can identify the problem to
mitigate the consequences of accident and of course preventing accident itself.
For Bhopal causes one of them is the failure of after tank safety process (leak mitigation
process). There are possibilities that the water enters the storage tank and run away reaction
occurs, refrigeration system fails to keep low temperature inside the vessel, for preventing explosion
to occur a safety valve will be opened. This valve is a type of rapture disc to allow the gas to go to
the next mitigation step. Next will be the vent gas scrubber. This scrubber will work as the gas will be
entered from its lower part and it will be sprayed by caustic soda solution which can neutralize the
MIC and convert it to harmless material. If it is not enough, then the residual will need to be sent to
the flare which will burn any MIC and convert it to be CO
2
gas. For this type of solution it can be
classified as the manual intervention that need to operate when failure happen.
However for as the maintenance for this safety operation was not close to good condition.
MIC storage tank alarms did not work for 4 years and there was only one feedback system while in a
similar plant in US there were 4 feedback systems. Plus, there were not storage tank prepared
between the large storage container and the MIC production unit to check its purity. On the other
hand reserve tank built was full with MIC whilst it should be emptied to allow evacuation of some of
the MIC from the other tank to reduce the pressure.
For the sake of minimizing operating cost, the refrigeration unit was shut down by setting
the temperature set point to 20
o
C instead of the 4.5
o
C as recommended in the operating manual.
The Freon liquids that need to be used for MIC cooling was drained and used within the plant.
Therefore, MIC was stored without cooling, and if a run-away reaction event should occur, no
cooling was available.
In addition to that, there should be slip blind plates that could be one of the preventing
measures for cleaning water in the pipes from entering MIC tank. However these plates were not
installed and their installation was ignored from the maintenance checklist. As for the scrubbers
were not well maintained, moreover they were not even working, during the disaster it was in
standby mode. MIC gas could not be neutralized it with caustic soda. Even it was activated, it could
not neutralize a huge volume of MIC gas released by the tank. Compared to plant in USA it had 4
times the number of vent gas scrubbers in the Bhopal plant.
For the flare tower was out of service for five months before the disaster because a length of
piping was corroded and was not replaced in contrast similar plant in USA has two flares. Material
used for safety valves and pipes in the factory were corrodible when exposed to acid. This was the
main reason for the safety devices malfunction. Other than that the existence of Iron Oxides with
water which entered the MIC tank acts as a catalyst accelerates its chemical reaction with water.
These are the problems that can be found in the controls system and safety measures that
can be very important in plant safety. The lack of critical alarms and operator supervision which are
part of the layer in LOPA was being omitted by the plant management.
In Procedural strategy it mainly consists of standard operating procedures (SOP), safety rules
and standard procedures, emergency response procedures and training. Base on the paragraph
above we can conclude that plant management failed to follow the standard operating procedures
of certain processes which cause the plant to explode.
In Bhopal incident there were different numbers victims estimated. The official number of
immediate deaths was 2259. Also some stated that other 8000 died after two weeks and another
8000 died as a result of diseases related to exposure to the gas. This shows that the lack of plant
emergency response and also community emergency response are almost not existed which cause
this huge number of deaths.
At time when this event occurred there are about 40 to 45 tons of MIC released out of the
vent gas scrubber. The gas is heavier than the air settled down and pushed by a gentle wind towards
Bhopal city. It was too late for the people in the city to react as the gas arrived and they were
suffocated. There was no warning or any emergency plan to evacuate the people as soon as possible.
The lack of community response was poorly shown by the developer of the plant as it has not
calculated the risk for the surrounding community that live near the plant. Bad turn to be worst
when victims arrived to the hospitals, the doctors didnt know how to deal with this poisonous gas.
The plant should have been providing the medical manual to the nearby hospitals in case that the
gas was released. There are none provided.
Workers in that plant were not given any rewards which turn them to behave in bad
manners and cause some the good employees to quit. In addition the manual given were in English
even some of them hardly understand it. Training should be given to the workers and also the
proper safety procedure should be followed in order this plant to comply the LOPA.
Conclusion that can be made from this accident, clearly it was from the poor management
systems. The safety process designs were omitted as they were try to imitate the plant in West
Virgina but made it in wrong ways. They ignored process and personnel safety regulations. Lastly,
Both Indian government and Union Carbide Corporation gave the priority to the profit. They did not
wary a lot about the life of indian citizens.
