Near midnight on June 27, 2016, an uncontrolled release of methane, ethane, propane, and several other hydrocarbons occurred at the Enterprise Products Gas Plant in Pascagoula, Mississippi. The hydrocarbons ignited and the plant suffered a series of fires and explosions over the next 18 hours. No one was injured.
The site subsequently shut down for almost six months. The incident cost the company $17.5 million.
The incident was due to thermal degradation of a heat exchanger. Similar problems had occurred nine times over a 17-year period at Enterprise but had been corrected before a fire broke out, according to an investigation and final report by the US Chemical Safety and Hazard Investigation Board issued Feb. 13.
The Enterprise plant receives raw natural gas via a pipeline from Gulf of Mexico deep-water oil wells. The plant separates the material into two products: natural gas liquids to be used as a chemical industry feedstock and a natural gas fuel stream that primarily contains methane.
More than 500 similar gas-processing facilities operate in the US and many use a cryogenic separation process with a brazed aluminum heat exchanger (BAHX) like the one that failed at Enterprise. The setup allows heat to transfer between different process streams while keeping the streams separate. Enterprise itself owns 26 midstream gas plants using similar cryogenic and BAHX technology.
“Extending the life cycle of equipment at these facilities requires more robust inspection protocols,” CSB interim executive Kristen Kulinowski says. “Operators shouldn’t take the risk of waiting to find a leak because, as this case demonstrates, that leak could result in a catastrophic failure.”
CSB is issuing recommendations to two trade associations, the American Petroleum Institute (API) and GPA Midstream Association, to share information related to failure hazards of BAHXs from thermal fatigue.
CSB also urges companies to develop more robust community alert networks that include social media and the ability to expand interactions with a community throughout an incident, following complaints from people living near the Enterprise plant that they did not know how to respond to the event.