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US Chemical Safety Board faults Pemex in 2024 fatal accident

By Thomson Reuters Feb 23, 2026 | 8:05 PM

By Erwin Seba

HOUSTON, Feb 23 (Reuters) – The lack of a standard system for correctly identifying idled equipment at Pemex’s Deer Park, Texas, refinery ​led to a poison gas release that ‌killed two workers, the U.S. Chemical Safety and Hazard Investigation Board (CSB) said in a report released on Monday.

Workers were preparing an idled, de-inventoried unit for upcoming work on October 10, ‌2024 ​when they opened a flange ⁠on a nearby pipe ⁠of an operating unit, the report said.

A total of 27,000 pounds of deadly hydrogen sulfide was released, killing one of the workers who opened the ​flange. As the gas drifted downwind, it overcame a worker who was unable to escape. He ⁠also died, the report said.

A ⁠Pemex spokesperson was not immediately available to ​discuss the report.

“The CSB concludes that PEMEX Deer Park ​had written procedures that standardize pipe marking for ‌pipe cutting but did not have a standardized process for flange opening and blind removal activities,” the board wrote. “Had PEMEX Deer Park required clear standardized markings ⁠for all line opening activities, this incident may have been prevented.”

Hydrogen sulfide concentrations during the release reached at least ⁠500 parts per ‌million at the Deer Park refinery, ⁠the board said. Thirteen other workers ​were ‌taken to medical facilities for evaluation. The ​Houston suburbs ⁠of Pasadena and Deer Park issued shelter-in-place orders during the release.

Since the release, the Pemex refinery has adopted a system for identifying equipment to be opened for work, the report said.

(Reporting by Erwin Seba; Editing ​by Edwina Gibbs)