A FIRE which resulted in the shutdown of major US LNG export facilities in June has been found to be due to isolation of cryogenic liquefied natural gas (LNG) in a piping segment without proper overpressure protection.
On 8 June, a fire broke out at Freeport LNG’s Quintana Island site on the Texas Gulf coast, prompting a shutdown and supply concerns. No fatalities or injuries were reported. Following the incident, Freeport said it expected partial operations to begin in September with full operations late in the year, but has since said that it anticipates phased restart to begin in early to mid-November with full capacity coming in March 2023. It is yet to announce a restart.
Freeport has already acted on recommendations to address root and contributing causes identified as part of an almost five-month long investigation by incident investigator IFO Group.
In its root cause failure analysis (RCFA), IFO concluded that the direct cause of the incident was isolation of a piping segment containing cryogenic LNG which lacked proper overpressure protection. Exposure to ambient conditions caused the LNG to warm and expand, resulting in a boiling liquid, expanding vapour explosion, or BLEVE, and rupture of the piping segment.
IFO also identified the root causes that led to the piping failure. It said that there were deficiencies in the pressure safety valve (PSV) testing procedure as well as the car seal programme, used for valve management. Another issue was that operating procedures allowed operators to close valves in a manner that allowed LNG to become isolated in a piping segment. IFO also said that Freeport failed to repurpose temperature indicator alarms used for cooldown operations during commissioning on LNG piping. These could warn of increasing temperatures in piping during operations.
Other contributing factors included a 2016 Hazard and Operability study that failed to evaluate the potential for a “blocked-in” LNG piping segment with inadequate overpressure protection, and to accurately and timely diagnose sudden pipe movement as being due to piping stresses from overpressuring of an adjacent piping segment.
In response to IFO’s recommendations, Freeport has significantly enhanced its PSV testing processes and car seal programme and implemented procedural changes to avoid the potential of LNG becoming blocked in piping segments. The company has also revised its control system logic to alert control room operators of valve positions and temperature readings that indicate LNG isolation.
Freeport is also updating its training programme to address incident causes and allow staff to identify and diagnose abnormal operating conditions at the facility.
It also made improvements based on a full, multi-month review by another, unnamed independent consultant of its LNG storage and transfer operating procedures, control systems maintenance and inspection procedures, and personnel qualification and training programmes. Freeport highlighted that it has executed an extensive, company-wide process safety management initiative to apply and reinforce process safety concepts into daily work processes across the organisation.
Freeport said: “The safety and security of our workforce and surrounding community, and environmental stewardship are Freeport LNG’s top priorities. Freeport LNG believes that transparency around the causes of this incident, and the remedial actions it is taking to ensure an incident of this nature never occurs again, is critical to maintaining public trust.”
The Quintana site has a liquefaction capacity of 15m t/y, equivalent to about 2.2bn ft3/d of gas. Its customers include BP, TotalEnergies, Osaka Gas, Jera, and SK, with contracts totalling 13.4m t/y of production capacity.
Catch up on the latest news, views and jobs from The Chemical Engineer. Below are the four latest issues. View a wider selection of the archive from within the Magazine section of this site.