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Bhopal Accident

Bhopal is probably the site of the greatest industrial disaster in history. Between 1977 and 1984, Union Carbide India Limited (UCIL), located within a crowded working class neighborhood in Bhopal, was licensed by the Madhya Pradesh Government to manufacture phosgene, monomethylamine (MMA), methylisocyanate (MIC) and the pesticide carbaryl, also known as Sevin.

On the night of the 2-3 December 1984 water inadvertently entered the MIC storage tank, where over 40 metric tons of MIC were being stored. The addition of water to the tank caused a runaway chemical reaction, resulting in a rapid rise in pressure and temperature. The heat generated by the reaction, the presence of higher than normal concentrations of chloroform, and the presence of an iron catalyst , produced by the corrosion of the stainless steel tank wall, resulted in a reaction of such momentum, that gases formed could not be contained by safety systems.

As a result, MIC and other reaction products, in liquid and vapor form, escaped from the plant into the surrounding areas. There was no warning for people surrounding the plant as the emergency sirens had been switched off. The effect on the people living in the shanty settlements just over the fence was immediate and devastating. Many died in their beds, others staggered from their homes, blinded and choking, to die in the street.

(graphic courtesy)

Many more died later after reaching hospitals and emergency aid centers. The early acute effects were vomiting and burning sensations in the eyes, nose and throat, and most deaths have been attributed to respiratory failure. For some, the toxic gas caused such massive internal secretions that their lungs became clogged with fluids, while for others, spasmodic constriction of the bronchial tubes led to suffocation. It is been estimated that at least 3000 people died as a result of this accident, while figures for the number of people injured currently range from 200,000 to 600,000, with an estimated 500,000 typically quoted. The factory was closed down after the accident.

The Bhopal disaster was the result of a combination of legal, technological, organizational, and human errors. The immediate cause of the chemical reaction was the seepage of water (500 liters) into the MIC storage tank. The results of this reaction were exacerbated by the failure of containment and safety measures and by a complete absence of community information and emergency procedures. (photo courtesy)

The long term effects were made worse by the absence of systems to care for and compensate the victims. Furthermore, safety standards and maintenance procedures at the plant had been deteriorating and ignored for months. A listing of the defects of the MIC unit runs as follows(reference):

  • Gauges measuring temperature and pressure in the various parts of the unit, including the crucial MIC storage tanks, were so notoriously unreliable that workers ignored early signs of trouble.

  • The refrigeration unit for keeping MIC at low temperatures (and therefore less likely to undergo overheating and expansion should a contaminant enter the tank) had been shut off for some time.

  • The gas scrubber, designed to neutralize any escaping MIC, had been shut off for maintenance. Even had it been operative, post-disaster inquiries revealed, the maximum pressure it could handle was only one-quarter that which was actually reached in the accident.

  • The flare tower, designed to burn off MIC escaping from the scrubber, was also turned off, waiting for replacement of a corroded piece of pipe. The tower, however, was inadequately designed for its task, as it was capable of handling only a quarter of the volume of gas released.

  • The water curtain, designed to neutralize any remaining gas, was too short to reach the top of the flare tower, from where the MIC was billowing

  • The lack of effective warning systems; the alarm on the storage tank failed to signal the increase in temperature on the night of the disaster

  • MIC storage tank number 610 was filled beyond recommended capacity; and -a storage tank which was supposed to be held in reserve for excess MIC already contained the MIC.

Other corrosion accidents: Aloha, Bhopal, Carlsbad, Davis-Besse, Guadalajara, EL AL, Erika, F-16, FAC, Flixborough, Gaylord Chemical, Oil pipeline releases, Pitting of aircraft and helicopters, Prudhoe Bay, Silver bridge, Swimming Pool