Chemical Safety Board finds fatal H2S release at Texas refinery was preventable

The U.S. Chemical Safety and Hazard Investigation Board (CSB) has released its final report into a fatal hydrogen sulfide release at the PEMEX Deer Park Refinery in Deer Park, Texas, concluding that the October 2024 incident was preventable and caused by critical safety failures.

Two contract workers were killed and 13 others hospitalized after more than 27,000 pounds of toxic hydrogen sulfide gas were released during maintenance activities in the refinery’s amine unit. The incident also prompted shelter-in-place orders for nearby communities.

According to the CSB report, the release occurred when workers mistakenly opened the wrong piping flange containing pressurized hydrogen sulfide instead of a nearby, safe line. The agency found that inadequate equipment identification, poor hazard assessment, and deviations from established procedures contributed to the incident.

“Two people died and the surrounding community was put at risk because of a completely preventable mistake,” said CSB Chair Steve Owens, emphasizing the need for clear hazard identification and effective safety procedures.

The investigation highlighted several systemic issues, including ineffective labelling of equipment, overly broad work permits lacking clear safety controls, and insufficient communication when workers were reassigned to hazardous operational units. Gaps between written procedures and actual practices were also identified.

The CSB issued recommendations to the refinery and to the American Society of Mechanical Engineers (ASME), including improved piping identification standards, stronger operational discipline, and the development of industry-wide guidance for safely marking equipment prior to maintenance.

The CSB noted that accidental releases from opening incorrect equipment remain a common hazard in the refining and chemical industries, underscoring the need for consistent and enforceable safety practices.