The US Pipeline and Hazardous Materials Safety Administration (PHMSA) earlier this week issued a heavily redacted report provided to Freeport LNG Development LP by IFO Group LLC addressing the causes of the June 8, 2022, explosion at Freeport’s 15-million tonne/year liquefaction plant on Quintana Island, Tex.
According to a statement by Freeport referencing the IFO report, the direct cause of the explosion was “isolation of a piping segment containing cryogenic LNG without proper overpressure protection, which LNG then warmed and expanded due to exposure to ambient conditions, resulting in a boiling liquid, expanding vapor explosion…and the rupturing of the piping segment.”
The report identified three root causes:
- Lack of both a pressure safety valve (PSV) testing procedure and a car seal program. A car seal program ensures that safety-critical valves are in the appropriate operating position i.e., open or closed.
- Lack of safeguards to warn operators of increasing vacuum insulated pipe (VIP) temperature.
- Lack of operational integrity of operating procedures.
Freeport listed contributing causes as:
- Failure of a 2016 hazard and operability study to evaluate the potential for a blocked-in LNG piping segment with inadequate overpressure protection.
- Failure to utilize management of change process for revisions to tank management operating procedures.
- Failure to accurately and timely diagnose sudden pipe movement as being due to piping stresses from the overpressuring of an adjacent piping segment.
- Operator fatigue as a result of significant overtime needs.
According to the report “more than one” control-board operator said that they were either not familiar with or had never seen the plant’s operating procedures. It also identified deficiencies in PSV testing procedures as contributing to human error that was part of the plant’s failure. Another cited human factor was alarm fatigue, noting that “there were alarms constantly indicating on equipment that had been placed out of service years ago.”
The report identified "severely damaged electrical conduit with open wiring” as the only “competent ignition source” in the area from which the explosion emanated.
The report recommended that Freeport develop a PSV testing procedure to include the use of car seals and considering formal training in same; consider performing a VIP alarm rationalization; and consider a complete review of tank-farm operating procedures.
Freeport's statement said it was implementing each of IFO’s recommendations. “Specifically, Freeport LNG has made significant enhancements to its PSV testing processes and car seal program, implemented procedural changes to avoid operating scenarios that could allow blocked-in LNG in piping segments, and revised its control system logic to alert control room operators to valve positions or temperature readings that indicate possible isolation of LNG in any piping segments,” the company said. “Freeport LNG is also updating its training program to address causes of the incident, as well as identification and diagnosis of abnormal operating conditions in the facility.”
The company also said it is in the process of increasing staffing by more than 30%.
PHMSA said its own investigation was ongoing and that despite accepting the redacted report it would later make an independent determination of what to exclude.