U.S. Chemical Safety and Hazard Investigation Board (CSB) Update on the H2S Release at PEMEX in Deer Park, Texas

The U.S. Chemical Safety and Hazard Investigation Board (CSB) released in November 2024 an investigation update with details on the fatal hydrogen sulfide (H2S) release at the PEMEX Deer Park Refinery in Deer Park, Texas, on October 10, 2024. The incident resulted in the deaths of two contract workers and injuries to thirteen others. Approximately 27,000 pounds of H2S were released, prompting a shelter-in-place order for nearby communities. According to the CSB, the investigation focuses on several key areas including permit-to-work practices, energy isolation procedures, contractor management systems, emergency response, hazard analyses, maintenance procedures, and respiratory protection policies. The investigation is ongoing, and a final report with findings and recommendations is forthcoming.

Incident Summary:

On October 10, 2024, at approximately 4:23 PM, a significant release of H2S occurred during a scheduled maintenance turnaround at the PEMEX Deer Park Refinery. The release fatally injured two contract workers employed by Repcon, Inc., an industrial services contractor. The incident led to the issuance of shelter-in-place orders affecting Deer Park and Pasadena, Texas, due to the hazardous nature of H2S.

Background Information:

? Refinery Ownership and Operation: The PEMEX Deer Park Refinery, located in Deer Park, Texas, is an indirect subsidiary of Petróleos Mexicanos (PEMEX), the Mexican state-owned petroleum company. Originally founded by Shell Oil Company, it became a joint venture with PEMEX in 1993, with PEMEX acquiring full ownership in 2022. The refinery employs approximately 1,000 personnel and 1,200 contract workers. The United Steelworkers union represents PEMEX's hourly employees.

? Repcon, Inc.'s Role: Repcon, Inc., a subsidiary of EMCOR Industrial Services, Inc., was contracted by PEMEX to perform maintenance work as part of a scheduled plant turnaround. Their work involved isolating piping segments in Amine Regeneration Unit 6 (ARU6).

? Hydrogen Sulfide (H2S): H2S is a colorless, highly toxic and flammable gas produced as a byproduct of crude oil refining. Even low concentrations can be immediately dangerous to life or health, and higher concentrations can cause near-instant death. H2S is heavier than air and tends to accumulate near the ground.

Incident Description:

? Maintenance Activities: On October 2nd, Repcon commenced work on the scheduled maintenance activities. On October 8th and 10th, PEMEX personnel requested Repcon workers to isolate certain piping segments in ARU6. This isolation work was completed by depressurizing and purging the segments with nitrogen.

? The Release: On October 10th, at 4:23 PM, two Repcon contract workers partially opened a flanged connection on adjacent ARU7 piping, where H2S was flowing at approximately 90% concentration and 15 pounds per square inch. This resulted in the release of a substantial amount of H2S. The ARU6 piping (where Repcon's permitted work was located) was only approximately five feet from the ARU7 flange that was opened.

? Additional Casualties: Two additional contract workers from a different company, working approximately 250 feet downwind of the release, also suffered injuries, with one fatality.

? Response and Aftermath: The H2S release lasted approximately one hour until it was contained by shutting upstream valves. Emergency responders were deployed, and thirteen other contract workers were transported to hospitals. Shelter-in-place orders were enacted for several hours in the surrounding areas.

Path Forward and Key Areas of Investigation:

The CSB’s investigation is ongoing, focusing on several key areas:

? Permit-to-Work Practices: The investigation will thoroughly examine the permit-to-work system in place at the refinery, ensuring adequate communication, risk assessment, and control measures. Were procedures followed correctly? Was there a sufficient understanding of the hazards involved and appropriate precautions taken?

? Energy Isolation Procedures: This involves evaluating the effectiveness of procedures to isolate energy sources, specifically focusing on the depressurization and purging of the piping segments. Did this procedure adequately prepare the area for maintenance? Was there proper verification of isolation before work commenced? Was there any communication failure between teams regarding isolation status?

? Contractor Management Systems: The investigation will scrutinize the contract management system, including the selection, training, supervision, and communication protocols for contractors working at the refinery. Were contractors adequately trained for H2S hazards? Were safety guidelines and communication protocols clear and followed? Was there adequate oversight and supervision of contractors?

? Emergency Preparedness and Response Systems: A critical examination of the refinery's emergency response plan is necessary, evaluating its effectiveness and timeliness. Was the response adequate to the scale of the incident? Were appropriate communication channels used to alert emergency services and neighboring communities? Were emergency procedures followed correctly?

? Emergency Communication Practices: The investigation will assess the effectiveness of emergency communication practices, including disseminating information during the incident. Were communication procedures clearly defined and effective? Were all relevant parties informed promptly?

? Hazard Analyses and Risk Assessments: A thorough review of the refinery's hazard analysis and risk assessment procedures will be undertaken to determine whether potential risks associated with H2S releases were identified and appropriately mitigated. Was a thorough risk assessment performed prior to the work? Were control measures implemented effectively? Were risks associated with adjacent operating equipment properly accounted for?

? Maintenance Procedures: The CSB will evaluate the maintenance procedures followed during the turnaround, focusing on best practices for working on and isolating potentially hazardous systems. Were proper maintenance and lockout/tagout procedures in place and followed? Were any deviations from the procedures?

? Training Programs: The adequacy of training programs for both PEMEX employees and contract workers will be assessed. Were workers adequately trained in H2S safety, including the identification of hazards, emergency response procedures, and the use of personal protective equipment (PPE)?

? Respiratory Protection Policies and Procedures: The investigation will examine the respiratory protection policies and procedures implemented at the refinery. Was the appropriate PPE provided to workers? Were workers trained in its proper use? Was the PPE appropriate for the hazard levels present?

? Remote Isolation Capability: The feasibility and effectiveness of using remote isolation capabilities to mitigate risks will be investigated. Could remote shut-off valves have been implemented to minimize the release of H2S?

Conclusion:

The CSB's investigation into the tragic H2S release at the PEMEX Deer Park Refinery is a crucial step in preventing future incidents. The detailed analysis of the contributing factors will inform recommendations to enhance safety protocols, improve contractor management, and strengthen emergency response capabilities across the petroleum refining industry. The final report will be critical for learning from this event and implementing lasting changes to improve worker safety and the protection of the public.

James A. Junkin, MS, CSP, MSP, SMS, ASP, CSHO is the chief executive officer of Mariner-Gulf Consulting & Services, LLC and the chair of the Veriforce Strategic Advisory Board and the past chair of Professional Safety journal’s editorial review board. James is a member of the Advisory Board for the National Association of Safety Professionals (NASP). He is Columbia Southern University’s 2022 Safety Professional of the Year (Runner Up), a 2023 recipient of the National Association of Environmental Management's (NAEM) 30 over 30 Award for excellence in the practice of occupational safety and health and sustainability, and the American Society of Safety Professionals (ASSP) 2024 Safety Professional of the Year for Training and Communications, and the recipient of the ASSP 2023-2024 Charles V. Culberson award. He is a much sought-after master trainer, keynote speaker, podcaster of The Risk Matrix, and author of numerous articles concerning occupational safety and health.