Safety lessons from chemical disasters
B. KARTHIKEYAN
ON MARCH 23, 2005, the worst industrial accident in a decade in the U.S. occurred at a BP refining facility at Texas. It killed 15 workers and injured 180 others.
A description of the accident by the U.S. Chemical Safety and hazard investigation Board (www.csb.gov) , which independently investigates chemical accidents, is given below:
"The accident occurred during the start-up of the refinery's isomerisation unit, when a distillation tower and attached blowdown drum were overfilled with highly flammable liquid hydrocarbons. Because the blowdown drum vented directly to the atmosphere, there was a release of highly flammable liquid and vapour onto the grounds of the refinery, causing a series of explosions and fires. Alarms and gauges that should have warned of the overfilling equipment failed to operate properly on the day of the accident."
A comparison of the preliminary findings of the accident at Texas by the CSB with the reasons for the Bhopal accident, where the toxic methyl iso cyanate gas leaked on the night of December 2, 1984, killing thousands of people, is given below:
Economic pressures compromising safety: "A 2003 external BP audit referred to the Texas City refinery's infrastructure and assets as "poor" and found what it termed a "checkbook mentality." Budgets were not large enough to manage all the risks, but rather than expanding the budget, expenditures were restricted to the money on hand, in the opinion of the BP auditors. Stringent budget cuts throughout the BP system caused a progressive deterioration of safety at the Texas City refinery."
In the Bhopal accident, the plant was incurring losses due to overcapacity. Cost cutting measures included the shutdown of safety systems such as the vent gas scrubber and the flare system which was provided to safely burn any escaping MIC. The refrigeration unit of the MIC storage tank was also switched off.
This elevated the tank temperature and when water entered the tank, it aided a runaway reaction to occur, causing MIC to be released. Manpower was also reduced, leading to improperly trained staff manning key positions. Malfunctioning valves and faulty gauges were never replaced.
Ineffective follow-up on safety audits: In the BP accident, "Several years of audits and reports had identified serious safety system deficiencies. However, the safety initiatives that were undertaken focused largely on improving personnel safety, rather than management systems, equipment design, and preventative maintenance programmes to help prevent the growing risk of major process accidents."
In the Bhopal accident, two years prior to the accident, a safety team from Union Carbide, U.S., visited the plant and raised many points, including the potential for release of toxic material in the MIC unit area, either due to equipment failure, operating problems or maintenance problems. However, these problems were never analysed for the root causes and preventive actions were not implemented.
No major accident occurs without sufficient warning. In the current era of cost cutting and manpower rationalising, decision makers in the chemical industry should not forget the safety of the plant. Investment in safety should be treated as an opportunity cost — the cost of an accident is always greater than the cost of preventing it. The lessons from Bhopal must not be forgotten.
karthikbee@yahoo.com
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