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Lessons Of Bhopal Tragedy And Increased Need Of Safety

BHOPAL is still alive. It will always alive till the concept of safety will alive, search of cause of accidents and remedial measures will alive and chemical threats of humanity will alive.

Much is said and published about Bhopal disaster. Still its talk is continued. This is because of the gravity of the accident causing deaths of more than 2500 lives, more than that badly affected, claims of lacs of rupees, politics penetrated and ultimate closer of the factory.

Why such severe accident took place and how can we prevent similar reoccurrence is an important lesson of Bhopal incident. It has the opened the eyes of our people and created worldwide safety awareness. That is why we have selected, first, this unique example to explain the concept of safety, causation analysis and basic rules of accident prevention.


The facts of the accident in brief

It was the night of 2/3 December 1984 when the night shift staff of the Union Carbide factory, Bhopal, took around 11 p.m. There were double-walled, partly buried S.S tanks (No. 610,611 and 619), each of 60 tones capacity and all containing the poisonous gas MIC (Methyl ico cyanate) to be used to produce a deadly pesticide carbaryl. At @ 11-30 p.m, workers in the plant realized, there was an MIC leak somewhere: their eyes began to tear. A few if 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-brack which ended at 12-40 a.m when the events had moved very fast. The temperature of the tank 610 and reached 250C, the top of its scale and the pressure was increased twenty time 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 heart. A white cloud drifting over the plant was moving towards the sleeping neighborhood.

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 neutralize 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 tone 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 150-200C which was unsafe. For approximately two hours, the safety valve remained opened releasing over 50,000 pounds of MIC (might also containing phosgene, chloroform, hydrogen cyanide, carbon dioxide etc) out of 90,000 pounds stored in the tank 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.

The Causes of the Accident


Unsafe Condition

From the published press reports they seem to be:

• The refrigeration system to keep the gas cool was since long.
• The vent gas scrubber was under designed, not repaired and
   not connected.
• The corroded flare tower pipe not replaced and not connected
• The water curtain jets were undersigned to reach the maximum
   height.
• All the three tanks were filled in while one ought to have kept
  empty to use as emergency bypass.
• The computerized pressure/temperature sensing system, a
   warning device to give alarm and to control the situation at
   the time of abnormal condition was no installed.
• The carbon steel valves were used instead of stainless steel
   and the valves were notorious for leaking.
• The instrument to check the valve-leakage were not available.
• The wind direction and velocity indicator was not installed to
   warn the people about leakage direction and severity.
• The neighboring community was not told of the significance of
   the danger alarm and the dangers posed by the material used
   in the Plant.
• Control instruments at the plant were faulty.
• Maintenance and operational practices were deteriorated.
• Chemical reactors, piping and valves were not perged, washed
  and aired before maintenance operations.
• The slip blind to disallow the water in the tank through the
   valve was Missing.
• Under qualified workers were running the factory.
• People with chemical engineering background were replaced by
   less Skilled operators.
• The strength was reduced from 850 to 642 during preceding
   two Years and the operations duty relieving system were
   suspended.
• The operation manual was grossly inadequate, not specifying
   all necessary emergency procedures to control abnormal
   conditions
•  At the time of accident, n the MIC control room, there was
   only one operator who found it virtually impossible to check
   the 70-odd panels indicators and controllers.
•  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.

Unsafe Actions
• The leak was not attended as soon as it was reported.
• The first information of, five-fold pressure rise was dismissed
   in the belief that the pressure gauge could be faulty.
• A newly recruited supervisor had asked a novice operator to
  clean a pipe and slip blind was not inserted while doing so
• The public siren was put on around I am nearly an hour after
   the gas leakage, and that too for a few minutes.
• 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 exerts 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 an impurity to keep it stable. The phosgene water reaction produced heat co and HCI. The heat and HCI acted as the accelerators of the polymerization of MIC leading to a runaway reaction. According to others, the increased temperature of MIC (It vaporize 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 violent reaction. Because of the colder night of December, the escaped MIC settled down and traveled downward covering the sleeping surroundings with the blanket of death and damages.

Remedial Measures

All the 25 major causes of accident described 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.

The Lessons and Increased Need of safety
The lessons will last for so many years. They are :

• General safety awareness must be increased all around.
• Factory owners and trainers must open their eyes to pay more
  attention on safety, Particularity to provide and maintain safety
  devices and to improve the working conditions.
• Workers including staff and supervisors must work more
   carefully
• Authorities must go in much details and must seek strict
   compliance of safety rules .No politics should intervene.
• Necessary amendments must be made in safety Laws.
• Safety literature, education and training must be increased.
• Wide publicity must be given to safety programs and safe work
   practices on Radio, T.V., Newspapers to make alert and
   educated the people maintain high standards of safety
• Safety councils, Labour Institutes and Associations/Unions of
  employers and employees must increase their safety
  contributions.
• All safety inspections must be carried out thoroughly with
  sufficient time, and for this purpose, the number of inspectors
  must be increased. All authorities under various safety Laws
  must take care of their provisions to uplift the manifold aspect
  of safety.
• The Government must provide more funds for safety staff,
   vehicles, instruments, literatures etc and towards aid/subsidy
   for safety planning.

All these lessons point out the increased need of safety. It recalls the basic concept of safety and basic rules of behavior. They are explained below in brief.

The concept of safety

Safety, in general terms means freedom or protection from danger. In an industrial context it means the minimization of contact between human and hazard and is predominantly concerned with the prevention of physical harm (injury) to an individual. This is an age-old concept as well as specific. Basic concept needs all basic, general, fundamental and primary safety rules, while specific concept includes specific safety knowledge to solve specific problems. The concept is engineering and physiological, scientific and human.

Branches (Area of work)

Industrial, Environmental, Road and Home safety are the main branches. Mechanical, Chemical, health and hygiene etc may form sub branches.

Wide coverage:

The coverage of concept of safety is very wide. It included all branches of engineering, science and technology health and hygiene.

The concept Development:

(1) Accident Prevention,
(2) Total Loss control and
(3) Total Loss prevention

Accident may be defined as an unexpected, unplanned event in a sequence of events, that occurs through a combination of causes. It results in physical harm (injury or disease) to an individual, damage to property, equipment, buildings etc, a near-miss, loss to the company, or any combination of theses effects.

Loss Control may be defined as a management system to reduce or eliminate all accidental loss or wastage of manpower, materials, machinery, methods, and product, money, time etc.


Loss prevention may be defined as the application of engineering techniques in order to reduce the occurrence of accidents that result in personal injury, damage to property, product, equipment, buildings etc and those accidents that have no end result in the near-miss accidents.

Chemical safety included all above aspects in chemical fields.

The accident Prevention:

First study the causes, chances or probabilities of accidents. They may be unsafe conditions, unsafe actions or their combination. Many illustrations can be given to explain this broad classification. Our illustration of Bhopal accident throws light on this classification.

Based on above determination and further study find out the appropriate remedial measures and apply them. Safe trail and error method may also be useful.

Basic Safety Rules.

Some basic attitudes, general principles or basic rules of safety are given below. They are applicable to all fields.

(1)Small things make perfection but perfection is no small thing. Safety should be made perfect by smallest precautions.

(2)Solution of a problem lies through the problems. To achieve safety try through all stages in sequence.

(3) Safety is duty as well right. Perform the duty and enjoy the right.
(4) It is the knowledge that works and not the designation.(like it is not the gun that
Fires, but it is the heart of iron which fires the gun).

(5) Increase the knowledge of safety, first perpendicular (ie in your own branch),then
Horizontal (ie in other or side branches)

(6) March beyond basic, from known to unknown, from general to specific, from divergence to convergence. Be the master of your subject.

(7) Be useful and humane to others. Fit the unfit to survive.

(8) Safety is human Engineering. Human must be at the center.

(9) Be always safety minded. Develop safety eye safety outlook and improve safety controls. Safety devices should be failsafe.

(10) Rules of safety should be absolute and not negotiable.

Keep these rules always in mind. They will help you to meet with the increased need of safety.
Though safety in each field is of equal importance, safety in chemical field needs more attention because of its specific nature. Chemical safety seems more complicated than civil, mechanical or electrical safety, because each chemical has many properties, many process many hazards and many controls. The state pressure, temperature, process parameters etc ,are also changeable. Many hazard data and complete reaction documents are still not available. Many hazards are known after the accident only as incase of Bhopal and so many incidents. Engineering controls may not be possible or available at many places. Control devices and personal protections are inadequate many times. Warning devices may either not be available or not be functioning well All these diversified working conditions and operational situations pose many dangers which need their proper knowledge and attention followed by proper safety measures and proper preventive as well as corrective maintenance.

 


 

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