Accumulation of a dangerous substance known as popcorn polymer in a temporary dead leg of piping is what led to the 2019 explosion and fire at a Port Neches, Texas chemical facility, according to a U.S. Chemical Safety and Hazard Investigation Board (CSB) report.
Popcorn polymer, which is prone to forming in processes with high-purity butadiene, had accumulated in the dead leg in piping, causing the substance to develop and exponentially expand until pressure caused the piping section to rupture, releasing butadiene that then exploded.
The resulting pressure wave destroyed parts of the facility and injured two employees of the facility’s operator, TPC Group, and a security contractor. Nearby homes and buildings were damaged in the blast, which was reportedly felt up to 30 miles away.
Local officials stated that process fluid that continued to escape from ruptured equipment fueled fires that burned for more than a month.
‘Known safety hazard was poorly managed, controlled’
“The incident at TPC was the result of a known safety hazard – popcorn polymer – that was poorly managed and controlled at the facility,” CSB Chairperson Steve Owens said. “The result was a catastrophic incident that caused hundreds of millions of dollars in damage to the facility and nearby homes and business and resulted in a mandatory evacuation being ordered for everyone within a four-mile radius of the facility.”
CSB investigators identified four safety issues which contributed to the incident, including:
- inadequate dead leg identification and control which didn’t identify all potential temporary dead legs within the unit, including the one that eventually ruptured
- failure to implement a 2016 process hazard analysis (PHA) action item recommending that piping associated with out-of-service equipment be flushed monthly
- insufficient internal policies to lead employees to shut down and clean the butadiene unit after it experienced exceedingly high levels of hazardous popcorn polymer, and
- lack of remotely operated emergency isolation valves, which could have minimized the initial release from the ruptured piping, preventing some of the subsequent explosions.
Process needed to identify, control dead legs
Recommendations the CSB made for preventing similar incidents include:
- having TPC Group develop and implement a process to identify and control dead legs in high-purity butadiene service, including requirements for identifying potential dead legs, implementing preventive design strategies, preventing popcorn polymer buildup, and effective management oversight, and
- revising the American Chemistry Council’s “Butadiene Product Stewardship Guidance Manual” to include guidance on identifying and controlling or eliminating dead legs in high-purity butadiene service, as well as provide guidance on a methodology to help identify what should be considered excessive or dangerous amounts of popcorn polymer in a unit.
“We believe our final report and recommendations will help facilities that handle and store large quantities of butadiene better control popcorn polymer formation and growth within their processes,” CSB Board Member Sylvia Johnson said. “Doing so can prevent another terrible incident like the one that occurred at TPC.”