22 September 2011 19:55 [Source: ICIS news]
HOUSTON (ICIS)--The US Chemical Safety Board (CSB) on Thursday recommended that DuPont revise its “near-miss reporting and investigation policy” at its Belle plant in West Virginia in the wake of a fatal phosgene leak in 2010.
In its final report on the incident, the panel also urged the Occupational Safety and Health Administration (OSHA) to revise safety standards for compressed gasses, and the American Chemistry Council (ACC) to advise producers against the use of certain kinds of hoses for the transfer of phosgene.
In July, the ACC slammed DuPont for “preventable safety shortcomings” in the series of accidents that killed a worker at the Belle facility. DuPont no loner uses phosgene unit at the site and said it has implemented several safety changes.
A series of accidents began on 22 January, 2010, when an alarm sounded, leading operators to discover that 2,000lb of methyl chloride, had been leaking unnoticed into the atmosphere for five days, CSB said.
The next morning, workers discovered a leak in a pipe carrying oleum, producing a cloud of sulphur trioxide.
A phosgene leak occurred earlier that day, and the exposed worker died the following day at a hospital, the CSB said.
“Our final report shows in detail how a series of preventable safety shortcomings – including failure to maintain the mechanical integrity of a critical phosgene hose – led to the accidents,” said board chairman Rafael Moure-Eraso.
CSB investigators found that the phosgene hose that burst in front of the worker was supposed to be changed at least once a month.
However, the hose had been in service for seven months. Furthermore, the CSB found the type of hose involved in the accident was susceptible to corrosion from phosgene.
The safety board said documents showed that as far back as 1987 DuPont officials realised the hazards of using braided stainless steel hoses lined with Teflon.
An expert employed at DuPont had recommended the use of more expensive hoses lined with Monel, a metal alloy used in highly corrosive conditions, the CSB said. However, the Monel hose was never used.
The CSB said it found common deficiencies in DuPont Belle plant safety management systems springing from all three accidents: maintenance and inspections, alarm recognition and management, accident investigation, emergency response and communications, and hazard recognition.
Regarding hazard recognition, the CSB recommended that the Belle facility “revise its near-miss reporting and investigation policy to emphasise anonymous participation by all employees so that minor problems can be addressed before they become serious”.
The board also recommended that OSHA revise its compressed gases standard to be at least as effective as the National Fire Protection Association (NFPA) standards.
“This would require secondary enclosures for highly toxic gases such as phosgene and provide for ventilation and treatment systems, interlocked failsafe shutdown valves, gas detection and alarm systems, piping system components, and similar layers of protection,” the CSB said.
Also, the board urged the ACC to adopt more stringent guidelines for the handling of phosgene and other toxic gases.
Specifically, the CSB asked the ACC to revise its phosgene safety manual to advise against the use of hoses for phosgene transfer that are made of materials subject to corrosion by chlorides.
DuPont said it was cooperating with the CSB and has implemented safety recommendations stemming from its internal investigation of the incident.
Also, the Belle plant was performing an operations safety review at each unit, has expanded the hazards review system to strengthen and improve employee participation and was initiating a new best practice for alarm management, DuPont said.
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