The TPC Group plant in Port Neches experienced a critical equipment failure nearly three months before a Thanksgiving Eve explosion and fire, federal investigators said Thursday in their most comprehensive assessment of the incident to date.
The U.S. Chemical Safety and Hazard Investigation Board’s formal report of the TPC investigation provides the first definitive facts regarding the Nov. 27 explosion that severely damaged the plant, injured three workers and led to widespread evacuations. The 13-page document also provides a timeline of events.
Investigators cited a chain reaction that led to the initial explosion and series of fires to “popcorn polymers.” These polymers can form in process equipment, especially in “dead leg” sections of piping where chemicals do not flow as regularly, and create blockages.
The CSB report found one section of pipe in the plant was blocked for nearly three months before it ruptured, releasing a vapor cloud of butadiene that ignited and triggered more fires.
“CSB has learned there was a history of popcorn polymer issues, and there was a dead leg in the system for over 80 days before the event,” executive director of investigations and recommendations Stephen Klejst said during an agency meeting on Thursday.
Popcorn polymers are named for their white, crunchy appearance and the sound they make while forming. Most industry manuals and the chemical guide for butadiene warn about how easily they can form in process equipment.
The Chemical Safety Board report included photos of a pipe that burst due to ruptures caused by popcorn polymers at the same Port Neches plant in 1999. The plant was owned at the time by Huntsman Corp. Houston-based TPC Group acquired the plant in 2006.
The photo shows the pipe bent and bulging from the pressure built up inside it from the blockage, with a long tear running horizontally up the steel.
Investigators also found that popcorn polymers had been an issue at that particular part of the facility since at least July 2019, and examination of other equipment showed that at least one safety valve was completely blocked by the compound.
The CSB said it wasn’t able to visually verify the source of the explosion because of the blast destruction. But it said data and testimony from workers on site allowed it to pinpoint the start of the event at 12:54 a.m. within the butadiene processing unit.
An estimated 6,000 gallons of product escaped in under a minute, formed a vapor cloud and ignited in a giant fireball less than two minutes after the equipment failure, according to the agency. Two workers were in the unit at the time of the release, and a third witnessed it from a short distance away. They were the only employees injured in the blast.
The factual update issued Thursday cited a report from global insurance broker Marsh/JLT, which calculated $500 million in property damage was caused by the incident as the blast sent shock waves across homes, businesses, other facilities and a school just a few blocks away.
Attorney Chip Ferguson, who represents local clients in a civil case against the company, said the update confirmed some initial hunches about the case.
“It raises more questions about the process and operational control,” he said, “and it supports what we thought happened but is no bigger or no smaller than that.”
The report does not say what TPC knew prior to the explosion, he noted.
“It hasn’t been addressed at all whether TPC has a reason or excuse, or just waved the white flag at the issue,” Ferguson said “We are going to want to know that. If I lived in Port Neches or Jefferson County, I would want to know what you were thinking when you let this happen in a dead leg for 80 days.”
TPC spokeswoman Sara Cronin said the company will enact any recommendations the federal agency makes.
“While the CSB has been conducting its investigation, TPC already has begun implementing a comprehensive program to review its systems for identifying and mitigating butadiene hazards,” Cronin said in an email to The Enterprise. “TPC has an Operational Excellence program in place with dedicated resources to address risk mitigation at our sites.”
Katherine A. Lemos, who chairs the safety board, said the TPC investigation should wrap up sometime in 2021.
TPC Group representatives will be back in state court in Orange County on Monday to continue working on a schedule for the civil case, which involves more than 1,000 people who claim damages from the explosion.