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Among the numerous safety recommendations made in the report: DuPont should enclose all of its phosgene production and storage areas so that any releases of phosgene will be contained. The CSB is also urging the Occupational Safety and Health Administration (OSHA) to update its compressed gas safety standard to include secondary enclosures for toxic gases such as phosgene.
The CSB also released an animation – available on its website (www.csb.gov) that depicts the sequence of events leading to the phosgene exposure.The draft report and recommendations remain subject to change and final approval by a vote of the presidentially-appointed board of the CSB. That vote is expected to occur following a 45-day comment period which closes on August 22.
CSB "surprised" by 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 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 the sulfur trioxide. The phosgene release occurred later that day, and the exposed worker died the next day in a hospital.
CSB Chairman Rafael Moure-Eraso said the three accidents particularly concerned CSB personnel given DuPont’s longstanding reputation for a commitment to safety. Noting the company started as a gunpowder manufacturer in 1802, and became a major chemical producer within 100 years, Dr. Moure-Eraso said, “DuPont has had a stated focus on accident prevention since its early days. Over the years, DuPont management worked to drive the injury rate down to zero through improved safety practices.”
Dr. Moure-Eraso continued, “DuPont became recognized across industry as a safety innovator and leader. We at the CSB were therefore quite surprised and alarmed to learn that DuPont had not just one but three accidents that occurred over a 33-hour period in January 2010.
CSB board member and former chairman John Bresland also spoke at the news conference: “These kinds of findings would cause us great concern in any chemical plant – but particularly in DuPont with its historically strong work and safety culture. In light of this, I would hope that DuPont officials are examining the safety culture company-wide.”
"Can we afford to take such action?"
Member 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 the braided stainless steel hoses lined with Teflon, or PTFE. An expert employed at DuPont recommended the use of hoses lined with Monel, a strong metal alloy used in highly corrosive conditions. 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 draft report indicate that in the 1980’s, 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. However, the documents show the company calculated the benefit ratio of potential lives saved compared to the cost 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?”
Near-misses didn't help avert accidents
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 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.”
The CSB draft report recommends 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.
The CSB draft recommends that the DuPont Corporation 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 draft report concluded that the most comprehensive guidelines are those set forth by the National Fire Protection Association, or NFPA.
The draft report recommends that industry-organizations such as the Compressed Gas Association (CGA) and the American Chemistry Council (ACC) adopt the more stringent guidelines of the NFPA for the safe handling of phosgene and other highly toxic gases.
The report recommends the Occupational Safety and Health Administration (OSHA) update its compressed gas safety standard to include modern safeguards for toxic gases such as phosgene. These improved safeguards include: Secondary enclosures for units using phosgene, mechanical ventilation systems, emergency phosgene scrubbers, and automated audible alarms.
Chairman Moure-Eraso said, “Adoption of the CSB recommendations by OSHA, the Compressed Gas Association and the American Chemistry Council and, would greatly increase the safe handling of toxic gases nationally, and will protect workers from the deadly exposures.”
Dr. Moure-Eraso noted that he welcomes today’s release of the draft report and invites public comment on it. “Comments concerning the draft report will be carefully considered following the public comment period, after which Board Members will vote on the findings and recommendations. The report is not final until the vote is taken.”
The CSB is an independent federal agency charged with investigating serious chemical accidents. The agency's board members are appointed by the president and confirmed by the Senate. CSB investigations look into all aspects of chemical accidents, including physical causes such as equipment failure as well as inadequacies in regulations, industry standards, and safety management systems.
The Board does not issue citations or fines but does make safety recommendations to plants, industry organizations, labor groups, and regulatory agencies such as OSHA and EPA.