Fatal Exposure: Tragedy at DuPont

Narrator: The DuPont Company of Wilmington, Delaware, was founded in 1802 as a gunpowder manufacturer. By the early 20th century, DuPont had become a major chemical company and today is one of the largest chemical manufacturers in the world, with some 58,000 employees in 80 countries. DuPont has clearly focused on accident prevention since its beginnings in explosives production. Over the years, DuPont management attempted to reduce the worker injury rate to zero through improved safety practices. Over time, DuPont became recognized throughout the industry as an innovator and leader in safety. Operator: 911. Caller: Yes, ma'am. My name is Debra Stanley. I'm at the DuPont plant in Belle, West Virginia.

I need an ambulance immediately. Narrator: But DuPont's safety reputation was shaken in January 2010, when three separate incidents occurred within 33 hours at the company's manufacturing plant in Belle, West Virginia; the last

fatal

one. The first involved a continuous release of methyl chloride from process equipment that went undetected for five days. The next morning, highly corrosive oleum was released through a hole in the process pipe and just six hours later, a transfer hose ruptured, releasing highly toxic phosgene. Bresland: Given the company's reputation as a safety leader, the Chemical Safety Board was especially concerned about this rapid succession of three accidents at a major DuPont facility.

Particularly concerning was the

fatal

release of highly toxic phosgene. Narrator: DuPont's facility in Belle, West Virginia, occupies more than 700 acres along the Kanawha River, eight miles east of Charleston, the state capital. The plant produces a variety of chemicals. On January 17, 2010, a production unit was commissioned after extensive maintenance. Methyl chloride, produced in a reaction vessel, flowed through an open rupture disk and escaped through an incorrectly located drain hole. The dangerous gas was vented inside, in an area not frequented by workers. Five days later, on January 22, an air monitor alarm inside the building alerted staff to the release.

Approximately 2,000 pounds of methyl chloride had escaped. Banks: When the rupture disk exploded, an alarm went off. But our investigation found that because of a history of false alarms, operators came to view this alarm as a nuisance that could be safely ignored. Narrator: The next day, plant operators discovered another release. Oleum, a concentrated form of sulfuric acid, had over time corroded the pipes in the plant's spent acid recovery unit. Steam from an attached copper tube mixed with the oleum and created a large hole in the tube. The oleum escaped through the hole and formed a vapor cloud, discovered by workers shortly after 7:00 a.m. m. on January 23.

Approximately 22 pounds of oleum were released. Tyler: The CSB discovered that DuPont had a previous oil leak, which led to a recommendation by the company to perform periodic maintenance inspections of the oil pipelines. But the CSB found this was not done due to ineffective communications between DuPont and its inspection contractors. Bresland: The third in a series of accidents at the Belle plant occurred just six hours after the oil leak and was fatal. It was phosgene, an industrial chemical so toxic that it was used as a chemical weapon in World War I. Narrator: Phosgene severely damages lung tissue.

This can cause a deadly buildup of fluid in the lungs, which may not appear until hours after

exposure

. The Belle plant's small-batch manufacturing unit purchased phosgene in one-ton cylinders from a third-party chemical company. The plant used phosgene to make five different pesticide intermediates. The cylinders were stored in a partially walled one-story structure called a phosgene shed, which was open to the atmosphere. During use, the cylinders were connected to other equipment by flexible stainless steel braided hoses. Inside each hose was a Teflon or PTFE liner. A hose used nitrogen to pressurize the cylinder, pushing liquid phosgene into the manufacturing process.

An electronic scale recorded the weight of each cylinder. And when it was almost empty, an alarm sounded in the control room. An operator then closed the valves of the empty cylinder and opened the valves of a second full cylinder. The stainless steel hoses leading to the empty vessel were purged of phosgene with nitrogen. The empty cylinder was then replaced with a new one on the scale. The day before the fatal phosgene release, operators experienced flow problems with one of the hoses and began switching between cylinders to avoid disrupting the chemical process. During the cylinder change, the valve closed on a partially filled cylinder.

However, the hose was not vented, allowing pressure to build up as the liquid phosgene inside heated. Sometime between 1:45 p.m. and 2:00 p.m. on January 23, a worker was inspecting one of the cylinders when the pressurized hose suddenly burst. Narrator: They sprayed his chest and face with a lethal dose of phosgene. Another worker was exposed to the deadly gas and a third was potentially exposed, but neither reported any symptoms. A total of two pounds of phosgene were released into the atmosphere. Monitors on the plant's fence detected small concentrations of the dangerous chemical. The worker who had been sprayed with phosgene called for help and was taken to a local hospital.

Four hours later, the worker's condition began to deteriorate rapidly and, despite medical treatment, he died one day after the accident. The CSB determined that the permeability of the transfer hoses to phosgene was a key factor in the accident. Banks: During our investigation, we discovered that the PTFE-lined stainless steel hoses used at the Belle plant are particularly susceptible to failure when phosgene is used. This is because phosgene can leach through the permeable PTFE coating and corrode stainless steel. Tyler: We also learned that another phosgene hose nearly failed in the same manner and was discovered just hours before the fatal phosgene release, but this did not prompt an investigation.

Narrator: DuPont standard operating procedure requires replacing hoses in phosgene service every 30 days. However, on the day of the accident, January 23, 2010, the phosgene hoses had not been changed in more than seven months. The software used to manage maintenance at the Belle plant had been modified and no longer notified operators when to replace hoses. As a result, the hoses remained in use much longer than the prescribed service life. Documents obtained during the CSB investigation showed that as early as 1987, DuPont officials became aware of the dangers of using braided stainless steel hoses lined with Teflon or PTFE. An expert employed at DuPont recommended the use of hoses coated with Monel, a tough metal alloy used in highly corrosive conditions.

The DuPont official stated: "It is true that Monel hose will cost more than its stainless steel counterpart. However, with proper construction and design that minimizes stresses, the service life should be much longer than three months, costs will be lower in the long term and security will also improve." But the CSB found that the Belle plant never followed the recommendation to install more durable Monel hoses. The CSB determined that there are safer ways in which DuPont could have conducted its phosgene operation. For example, the phosgene cylinders should have been stored in a closed room, equipped with a ventilation system and a scrubber.

If the facility was designed for human entry, workers should have been required to wear fully encapsulated protective equipment. Documents from 1988 show that DuPont considered building a facility for the phosgene operation, but then decided against it. A DuPont official wrote: "It is possible that under current circumstances the company could afford $2 million for a facility. However, in the long term, can we afford to take such a step, which has such a small impact on However, it sets a precedent for all highly toxic material activities. DuPont decided not to lock in the phosgene unit at that time, but the possibility of a deadly release remained a concern.

The danger was noted in a 2004 process risk analysis, which recommended building an enclosure equipped with a scrubber. The facility was originally scheduled to be completed in December 2005, but the deadline was extended four times and had not yet been met by January 2010... when the fatal phosgene release occurred. Tyler: Without an enclosure around the phosgene operation, there were no barriers to prevent phosgene from exposing operators or traveling off-site. Banks: Industry groups have established several good practices for the safe handling of phosgene and other highly toxic materials in compressed gas cylinders. The CSB found that the most comprehensive guidelines are those established by the National Fire Protection Association, or NFPA.

Narrator: The CSB recommended that industry organizations, such as the Compressed Gas Association and the American Chemistry Council, adopt the NFPA's stricter guidelines for the safe handling of phosgene and other highly toxic gases. And the CSB asked OSHA to update its compressed gas safety standard to include modern safeguards for toxic gases. The CSB recommended that these enhanced safeguards include: secondary enclosures for units using phosgene. Mechanical ventilation systems. Emergency phosgene scrubbers and automated audible alarms. Tyler: We found that each of the three serious incidents at DuPont's Belle plant was preceded by another event or series of events. However, these early warnings and near misses did not lead to measures to prevent their recurrence.

Narrator: The CSB recommended that the DuPont Belle facility revise its near-miss investigation and reporting policy to emphasize anonymous participation by all employees so that minor problems can be addressed before they become serious. Bresland: The incidents at DuPont show that tragedies can happen, even in companies with a highly respected safety culture. Safer practices and adequate attention to near misses are essential for a company to achieve the goal of zero incidents, such as that aspired to by DuPont. Thank you for watching this CSB safety video. Narrator: For more information about the CSB investigation into the accidents at DuPont, visit CSB.gov.