CSB Safety Video: The Danger of Popcorn Polymer - An Incident at the TPC Group Chemical Plant

U.S. Chemical Safety and Hazard Investigation Board (CSB), July 19, 2023

The U.S. Chemical Safety and Hazard Investigation Board (CSB) has released a new safety video on its investigation into the serious November 2019 incident at the TPC Group Chemical Plant in Port Neches, Texas. A series of explosions destroyed a portion of the TPC facility, damaged nearby homes and businesses, and prompted a mandatory evacuation of residents living within four miles of the plant. Several workers and members of the public reported injuries and fires burned at the facility for over a month. The incident caused $450 million in on-site property damage and $153 million in off-site property damage to nearby homes and businesses. Media reports indicated that the blast was felt up to 30 miles away.

The CSB's new safety video, called “The Danger of Popcorn Polymer: Incident at the TPC Group Chemical Plant,” includes an animation of the events leading to the incident, and interviews with both CSB Board Member Dr. Sylvia Johnson and the CSB’s Lead Investigator for the incident, Butch Griffin.

The CSB’s investigation found that the incident at the TPC plant was the result of inadequate management of a hazard called “popcorn polymer,” which is well known to plants, such as TPC, that handle or produce butadiene. The popcorn polymer grew and formed inside a “dead leg” in piping that was created when a process pump was taken out of service for several months. Over a period of 114 days, without recognition by the plant, the popcorn polymer exponentially expanded inside the dead leg until pressure caused the piping section to rupture, releasing flammable butadiene that quickly exploded.

In the safety video Board Member Johnson states, “The incident at TPC was the result of a known hazard where popcorn polymer grew and formed inside equipment that was poorly managed and controlled at the facility. Gaps in industry good guidance on the management of popcorn polymer formation played a role. The result was a catastrophic incident that disrupted life at the facility as well as the local community.

As in the CSB’s final investigation report, the safety video covers the four key safety issues that contributed to the incident. They are: (i) dead leg identification and control, (ii) process hazard analysis action item implementation, (iii) control and prevention of popcorn polymer, and (iv) remotely operated emergency isolation valves. The video also highlights safety recommendations made by the CSB to the TPC Group as well as the American Chemistry Council.

Board Member Johnson closes the video by saying, “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. Doing so can prevent another terrible incident like the one that occurred at TPC.



About the CSB

The CSB is an independent, non-regulatory federal agency whose mission is to drive chemical safety change through independent investigations to protect people and the environment. The agency’s board members are appointed by the President and confirmed by the Senate. CSB investigations look into all aspects of chemical incidents, including physical causes such as equipment failure as well as inadequacies in regulations, industry standards, and safety management systems. The CSB does not issue citations or fines but makes safety recommendations to companies, industry organizations, labor groups, and regulatory agencies such as OSHA and EPA. For more information, please visit

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