CSB: Design Flaws Led to Deadly Gas Leak at DuPont

On Thursday, the U.S. Chemical Safety Board (CSB) revealed the initial findings from their investigation into the deadly gas leak that took the lives of four workers at Dupont's chemical plant in LaPorte, TX. Rafael Moure-Eraso, Chairperson of the CSB, pointed out that although DuPont has made great efforts to improve safety at their facilities and in fact, is generally recognized around the industry as a leader in safety, the company has also had three deadly incidents in the last five years; the latest of which was the poisonous gas leak at their LaPorte plant last November. He went on to say that "not only DuPont, but the industry as a whole must do much better," and that "it is clear that the current process safety regulatory system is in need of reform."

The CSB noted that in their initial field investigation of the LaPorte incident, which is only 50% complete, the team has identified four design issues that contributed to the accident:

1. The process included several interconnections between the methyl mercaptan supply line and a chemical vent system, which allowed a toxic leak into an unexpected location, where workers were exposed with fatal consequences.
2. The chemical vent system - which was intended to safely remove harmful vapor from process vessels – had a design shortcoming that allowed liquid to accumulate inside.  This liquid regularly caused pressure buildups in the vent, and the liquid needed to be manually drained by operators to prevent safety issues from interconnected equipment, such as reactors.
3. The vent drain that operators had to use was open to the atmosphere, meaning that workers were exposed to whatever chemicals were drained from the vent system.
4. The building was designed in such a way that even had ventilation fans been working on the day of the accident, it could not necessarily protect workers from chemical exposure.  And we found that those vents were not, in fact, working at the time of the accident.

Before turning things over to CSB Board Member Manny Ehrlich, Moure-Eraso pointed out that this incident is one of many similar incidents investigated by the CSB and that it reinforces the need for "regulators and companies [to] place greater emphasis on making designs as safe and possible and updating them on a constant basis."