BHOPAL GAS DISASTER

BHOPAL GAS DISASTER

It was the night of 2nd December 1984 when the night shift staff of the Union Carbide Factory, Bhopal, took a round at @ II pm. There were three double walled, partly buried S.S. tanks (No. 610, 611 and 619) each of 60 tonne capacity and all containing the poisonous gas MIC (Methyl isocyanate) to be used to produce a deadly pesticide Carbaryl. At @ 11-30 pm. workers in the plant realised that there was a MIC leak some where : their eyes began to tear. A few of them went to the MIC structure and noticed a drip of liquid with yellowish-white gas, about 50 feet of the ground. They told .the supervisor who, however, decided to deal with the leak after the tea-break which ended at 1240 night. Meanwhile the events had moved very fast.

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 The temperature of the tank 610 had reached 25°C the top of its scale and the pressure was increased twenty times rushing towards 40 psi at which the emergency safety valve was to open. Soon the pressure gauge showed 55 psi, the top of the scale and the safety valve had opened releasing MIC With a loud hissing sound and the tremendous heat.  A white cloud drifting over. the plant was. moving towards the sleeping neighbourhood.

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 The workers tried to operate the safety devices, but nothing seemed to work. The water jet failed to reach the top of the 120 feet stack from which MIC was escaping.  The vent gas scrubber to neutralise the escaping gas did not work. The scrubber was under maintenance,, the flow meter was not indicating the circulation of caustic soda whose concentration was also not known since October. The flare tower to burn off the gas could not be 'used because its piping was corroded and not replaced. The refrigeration system, of 30 tonne capacity, to keep the MIC in liquid state at 0°C was closed down since June 1984 as an economy drive and the gas was at 15°-20°C Which was unsafe. For approximately two hours, the safety valve remained opened releasing over 50000 pounds of MIC (might also containing Phosgene, Chloroform, Hydrogen cyanide. Carbon dioxide etc.) out of 90000 pounds stored in the tank No. 610 at the time of the incident. Sometime between 1-30 to 2-30 am. the safety valve reseated as the tank pressure went below 40 psi.

BHOPAL GAS DISASTER UNSAFE CONDITION

Unsafe Conditions

 From the published press reports they seem to be:

1.         The refrigeration system to keep the gas cool was closed since long.

2.         The vent gas scrubber was under designed, not repaired and not connected.

3.         The corroded flare tower pipe not replaced and not connected.

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4.         The water curtain jests were underdesigned to reach the maximum height.

5.         All the three tanks were filled in while one ought to have kept empty to use as emergency bypass.

6.         The computerised pressure/temperature sensing system, a warning device to give alarm and to control the situation at the time of abnormal condition was not installed.

7.         The carbon steel valves were used instead of stainless steel and the valves 'were notorious for leaking.

8.         The instruments to check the valve-leakage were not available.

9.         The wind direction and velocity indicator was not installed to warn the people about leakage direction and severity.

10.       The neighbouring community was not told of the significance of the danger alarm and the dangers posed by the materials used in the plant.

11.       Control instruments at the plant were faulty.

12.       Maintenance and operational practices were deteriorated.

13.       Chemical reactors, piping and valves were not purged, washed and aired before maintenance operations.

14.       The blind disc to disallow the water in the tank through the valve was missing.

15.       Under qualified workers were running the factory.

16.       People with chemical engineering background were replaced by less skilled operators.

17.       The workers' strength was reduced from 850 to 642 during preceding two years and the operators duty relieving system was suspended.

18.       The operating manual was grossly inadequate, not specifying all necessary emergency procedures to control abnormal conditions.

19.       At the time of accident, in the MIC control room, there was only one operator who found it virtually impossible to check the 70-odd panels, indicators and controllers.

20.       A design modification of jumper line to interconnect relief valve vent header and the process vent header was defective, as it allowed the water to go into the MIC tank.

BHOPAL GAS DISASTER UNSAFE REACTIONS

Unsafe Actions:

 1.         The leak was not attended as soon as it was reported. Initial time passed in tea break.

2.         The first information of five-fold pressure rise was dismissed in the belief that the pressure gauge could be faulty.

3.         A newly recruited supervisor had asked a novice operator to clean a pipe and the blind disc was not inserted while doing so.

4.         The public siren was put on around 1 am. nearly an hour after the gas leakage and that too for a few minutes.

5.         The correct antidotes and medical treatments were not suggested to surrounding doctors. On the contrary confusion of MIC or Phosgene or Hydrogen cyanide was confounded.

     Unsafe Reactions:

 Above unsafe conditions and actions lead to the violent unsafe reaction. Different hypothesis have been expounded by Carbide's scientists, Indian experts and Dr. S. Varadrajan, who lead the investigations on behalf of the Government.  According to him small quantity of water reacted with Phosgene in the tank, mixed with MIC as animpurity to make it unstable. The Phosgene water reaction (hydrolysis) produced heat, CO₂, and HCI.  The heat and HCI acted as the accelerators of the polymerisation, additions and degradation of MIC leading to a runaway reaction. According to others, the increased temperature of MIC (it vaporises above 38°C) generated heat, pressure and side-reactions, higher than normal amount of Chloroform in the stored MIC and an iron catalyst lead to the violet reaction.  Because of the colder night of December, the escaped MIC settled down and travelled downward covering the sleeping surroundings with the blanket of death and damages.

BHOPAL GAS DISASTER REMEDIAL MEASURES

Remedial Measures :

 All the 25 major causes of this accident stated above in (A) and (B) suggest the remedial measures. To avoid repetition, all these contributing causes should be removed first and necessary steps should be taken to run the plant always safe and sound, with all the safety devices properly working.  The working conditions must be improved and unsafe actions must be removed by proper policy, training and education.

 Lessons of Bhopal are well described in the foreword to the IOCU (International Organisation of Consumers Union) in the following words :

 "..  the deadly cloud that wrought havoc at Bhopal... will continue to rear its ugly head in many forms, in many sizes and in many places. Obviously there are many lessons to be learnt about occupational health and safety, about proper sitting of production facilities, about science and technology, about access to information, about trade secrecy, about 'cover ups', about 'double standards',  about medical and legal remedies, about the responsibilities of transnational corporations, governments and international agencies and most crucial of all about what ordinary people can and must do to protect themselves from the plague of such deadly clouds."

 Bhopal incident opened the eyes and gave many lessons for the multinationals, for developed countries and for the developing countries.

 Human life must be equally valued everywhere. No double standard for developed and developing countries. 'Right to know' and 'Obligation to tell' concepts are to be covered by legislation. Training to staff, and workers, emergency procedures, highest standards for plant operation and maintenance and safety equipment, 'worst case' study and assessment, etc. were incorporated in 1987 by the amendment of our Factories Act, 1948.