CSB Report: “Popcorn Polymer” Led to Explosions and $583M in Damages

At a chemical plant in Texas, pressure buildup causes a pipe to rupture. Within minutes, six thousand gallons of flammable butadiene gas leaks from the pipe, vaporizes, ignites, and explodes. A series of explosions follow that cause $583 million in damages to the plant and the surrounding area. 

The incident described happened in the city of Port Neches on the night before Thanksgiving in 2019. In December 2022, the US Chemical Safety and Hazard Investigation Board (CSB) issued a final Investigation Report focused on the accident that includes safety recommendations and key lessons for industry. 

The pipe that burst was 35 feet long and closed off at one end. The pressure buildup was caused by “popcorn polymer”—also known as crystalline polybutadiene—that can rapidly accumulate inside of equipment that handles high-purity butadiene. 

Dangers of "Dead Legs" in Process Equipment 

Some recommendations in CSB's Final Report relate to dead legs—sections of pipe or equipment that are not in use (permanently or temporarily), in which hazardous chemicals, chemical vapors, or water can accumulate. If these "dead leg" areas are not addressed when processing high-purity butadiene (as in this case), popcorn polymer can “grow” unnoticed. The substance expands and accumulates in a chain reaction until the pipe or vessel ruptures.

3 Key Lessons for Industry

The Final Investigation Report on the Port Neches, TX butadiene incident includes three “key lessons for industry.” CSB provides some practical guidance about implementing these lessons learned, and puts forth five safety recommendations in the full report linked above. 

1. Companies should establish a process to identify, control, or eliminate dead legs in operations susceptible to popcorn polymer formation...

2. …Butadiene facilities should develop robust policies to prevent and control popcorn polymer development and growth based on industry guidance, such as thorough equipment passivation, controlling oxygen levels, through chemical inhibitors, and other best practice methods.

3. Companies that handle large inventories of flammable or toxic material should assess their capability to remotely isolate these inventories in the event of a loss of process containment.

Alleged OSHA Violations

OSHA inspected the facility after the incident and cited the employer for two willful violations of the Process Safety Management (PSM) Standard related to the explosion and fire:

• Failure to implement adequate process safety procedures [(29 CFR 1910.119(f)(1))], and
• Not correct deficiencies in equipment to assure safe operations [(29 CFR 1910.119(j)(5)]

OSHA also cited the employer for violating the General Duty Clause of the OSH Act of 1970 (Section (5)(a)(1)), which requires employers to provide a workplace free of recognized hazards that are likely to cause death, or serious physical harm.

For these violations, the owners of the facility faced more $500,000 civil penalties. As of January 2022, the maximum monetary penalty for each “willful violation” is about $145,000.

Updating the PSM Standard

OSHA held a public meeting with stakeholders late last year to discuss an ongoing rulemaking project to "modernize" the Process Safety Management (PSM) Standard in 29 CFR 1910.1119 (Details).