CSB Releases Update on Investigation of Fatal Hydrogen Sulfide Release at Texas Refinery

Two workers died and 13 others were admitted to local hospitals in October following a release of approximately 27,000 pounds of hydrogen sulfide gas at the PEMEX refinery in Deer Park, Texas. The cities of Deer Park and Pasadena issued shelter-in-place orders in response to the release.

A preliminary report from the U.S. Chemical Safety and Hazard Investigation Board indicates that a segment of piping at the plant had been depressurized, purged, and isolated in preparation for regular maintenance. But two contract workers who attempted to perform the maintenance on Oct. 10 opened a flange on an adjacent pipe approximately five feet away from the purged pipe. The discharge fatally injured one of the maintenance workers. A second contract worker who was performing unrelated work about 250 feet away was also killed.

The IDLH (immediately dangerous to life or health) value for hydrogen sulfide is 100 ppm. CSB notes that concentrations exceeding 1,000 ppm can cause death almost immediately.

CSB’s investigation is ongoing. For more information, read the agency’s preliminary report.