Final report on three accidents at DuPont Belle (West Virginia) is released by the CSB
Published: 23 September, 2011
Investigation finds lack of safe equipment design, ineffective mechanical integrity programs, and failure to investigate near misses.
The US Chemical Safety Board (CSB) today released its final report on a series of three accidents that occurred over a 33-hour period on January 22 and 23, 2010, at the DuPont Corporation’s Belle, West Virginia, chemical manufacturing plant – including a fatal release of deadly phosgene gas, which was used as a chemical weapon in World War One.
CSB Chairperson Rafael Moure-Eraso 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. That this happened at a company with DuPont’s reputation for safety should indicate the need for every chemical plant to redouble their efforts to analyze potential hazards and take steps to prevent tragedy.’
The CSB also released a safety video today entitled ‘Fatal Exposure: Tragedy at DuPont,’ based on the investigation, which features an animation depicting the sequence of events leading to the death of a worker when a phosgene hose suddenly burst. The video also explains the causes of two other toxic chemical releases detailed in the report and features comments by Board Member John Bresland, CSB Investigation Team Lead Johnnie Banks and Investigator Lucy Tyler.
The report makes numerous safety recommendations. Among them, DuPont was urged to enclose all of its phosgene production and storage areas so that any releases of phosgene will be contained. (The Belle facility subsequently announced it was ceasing phosgene usage in 2011, and had no plans to resume use.)
The CSB recommended that the Occupational Safety and Health Administration (OSHA) revise the General Industry Standard for Compressed Gases to be at least as effective as the relevant National Fire Protection Association (NFPA) Code 55 (the Compressed Gases and Cryogenics Fluids Code). 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 accidents
DuPont’s Belle facility occupies more than 700 acres along the Kanawha River, eight miles east of Charleston, the state capital. The plant produces a variety of specialty chemicals.
The series of accidents began on January 22, 2010, when an alarm sounded leading operators to discover that 2,000 pounds of methyl chloride, a toxic and extremely flammable gas, had been leaking unnoticed into the atmosphere for five days. The next morning, workers discovered a leak in a pipe carrying oleum, producing a fuming cloud of sulfur trioxide. The phosgene release occurred later that day, and the exposed worker died the next evening in a Charleston hospital.
CSB board member and former chairman John Bresland noted the CSB finding that the phosgene hose that burst in front of a worker was supposed to be changed out at least once a month. But the hose that failed 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.
Team Lead Johnnie Banks said, ‘Documents obtained during the CSB investigation showed that as far back as 1987, DuPont officials realized the hazards of using braided stainless steel hoses lined with Teflon, or polytetrafluoroethylene (PTFE). An expert employed at DuPont recommended the use of hoses lined with Monel, a metal alloy used in corrosive applications. The DuPont official stated: “Admittedly, the Monel hose will cost more than its stainless counterpart. However, with proper construction and design so that stresses are minimized…useful life should be much greater than 3 months. Costs will be less in the long run and safety will also be improved.”’
In fact, the Monel hose was never used.
Internal DuPont documents released with the CSB report indicate that in the 1980s, company officials considered increasing the safety of the area of the plant where phosgene is handled by enclosing the area and venting the enclosure through a scrubber system to destroy any toxic phosgene gas before it entered the atmosphere. The analysis concluded that an enclosure was the safest option for both workers and the public. However, the documents indicate the company was concerned with containing costs and decided not to make the safety improvements. A DuPont employee wrote in 1988, ‘It may be that in the present circumstances the business can afford $2 million for an enclosure; however, in the long run can we afford to take such action which has such a small impact on safety and yet sets a precedent for all highly toxic material activities.[sic]’
The need for an enclosure was reiterated in a 2004 process hazard analysis conducted by DuPont, but four extensions were granted by DuPont management between 2004 and 2009, and at the time of the January 2010 release, no safety enclosure or scrubber system had been constructed. CSB investigators concluded that an enclosure, scrubber system, and routine requirement for protective breathing equipment before personnel entered the enclosure would have prevented any personnel exposures or injuries.
The CSB investigation 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.
CSB Team Lead Banks said, ‘The CSB found that each incident was preceded by an event or multiple events that triggered internal incident investigations by DuPont, which then issued recommendations and corrective actions. But this activity was not sufficient to prevent the accidents from recurring.’
Recommendations
The CSB recommended that the DuPont Belle facility revise its near-miss reporting and investigation policy to emphasize anonymous participation by all employees so that minor problems can be addressed before they become serious. The CSB report also recommends the Belle plant ensure that its computer systems will provide effective scheduling of preventive maintenance to require, for example, that phosgene hoses get replaced on time.
For the DuPont Corporation, the Board recommended the company require all phosgene production and storage areas company-wide have secondary enclosures, mechanical ventilation systems, emergency phosgene scrubbers, and automated audible alarms, which are at a minimum consistent with the standards of the National Fire Protection Code 55 for highly toxic gases.
Industry groups have established various good practices for the safe handling of phosgene and other highly toxic materials in compressed gas cylinders. The report concluded that the most comprehensive guidelines are those set forth by the National Fire Protection Association, or NFPA.
The Board recommended that an industry group, the Compressed Gas Association (CGA) adopt the more stringent guidelines of NFPA Code 55 for the safe handling of phosgene and other highly toxic gases.
The American Chemistry Council (ACC), a prominent chemical industry trade association, was urged to revise its Phosgene Safe Practices Guidelines Manual. The Board recommended the manual advise against the use of hoses for phosgene transfer that are constructed of permeable cores and materials that are subject to corrosion by chlorides. And the ACC was urged to include guidance for the immediate reporting and investigation of all potential near-miss phosgene releases.
Chairman Moure-Eraso said, ‘Adoption of the CSB recommendations by OSHA, the Compressed Gas Association and the American Chemistry Council will greatly improve the safe handling of toxic gases nationally and will protect workers from deadly exposures.’
To view the report click here.
To see the video, click below:
