The U.S. Chemical Safety and Hazard Investigation Board (CSB) today released its final investigation report into the fatal October 10, 2024, release of toxic hydrogen sulfide (H2S) at a Refinery in Deer Park, Texas. Two (2) contract workers died as a result of exposure to the toxic gas, 13 others were transported to local medical facilities, and dozens more were treated at the scene. Over 27,000 pounds of toxic hydrogen sulfide gas were released during the incident, and a shelter-in-place order was issued for two (2) neighboring cities.
The release occurred at approximately 4:23 p.m. on October 10, 2024, during maintenance activities in the refinery’s Amine Unit when contract workers mistakenly opened a flange on piping that contained pressurized hydrogen sulfide. The workers were supposed to open a different flange on piping that was located approximately five (5) feet away. One contractor worker was fatally injured when the gas was released. The hydrogen sulfide vapor subsequently traveled downwind into an adjacent unit, where a worker employed by another contractor inhaled the toxic gas and was also fatally injured.
The release continued for nearly one (1) hour until refinery emergency responders reassembled the leaking flange and stopped the discharge. Because of the release, local officials in the neighboring cities of Deer Park and Pasadena, Texas, issued shelter-in-place orders that remained in effect for several hours. Although the refinery did not sustain physical structural damage, the company reported approximately $12.3 million in property damage related to loss of use of the Amine Unit and downstream processes.
The CSB’s final report further identifies several key safety issues:
- Positive Equipment Identification: The CSB found that the refinery lacked an effective method to clearly identify the correct piping flange before work began. Drawings and flange lists were insufficient to distinguish nearly identical segments, and the identification tag for the correct flange was placed out of view. Without reliable identification, workers searched for unlocked flange devices similar to what they had seen elsewhere in the refinery. The CSB noted that accidental releases from opening the wrong equipment are common in the chemical and refining industries and that no industry-wide standard currently addresses this issue.
- Work Permitting and Hazard Control: The refinery issued a broad work permit covering multiple jobs with varying hazards and without clear hold points. Workers overlooked a written instruction to stop work and obtain an operator’s presence before opening the hydrogen sulfide piping. The permit also failed to address the hazard of opening piping in an operational unit upwind of other contractors.
- Turnaround Contractor Management: On the day of the incident, workers were reassigned from a shutdown unit to a partially operational unit containing hydrogen sulfide. This abrupt change, combined with the proximity of the units, led workers to believe they were still working in the shutdown environment, and they were not specifically informed of the risks in the operational unit.
- Conduct of Operations: The CSB identified gaps between written procedures and actual practices at the facility. While the refinery’s policies aligned with industry standards, management and operations personnel often misunderstood or deviated from them, contributing to failures in work permitting and hazard evaluation.
CLICK HERE for the full report