Report: Valve removed accidently caused 2021 Fatal Acid Release at LyondellBasell La Porte Complex
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Report: Valve removed accidently caused 2021 Fatal Acid Release at LyondellBasell La Porte Complex

May 22, 2023


La Porte, Texas - On Friday, the U.S. Chemical Safety and Hazard Investigation Board (CSB) released its final report into the July 27, 2021, fatal acetic acid release at the LyondellBasell La Porte Complex in La Porte, Texas.

The CSB’s report found that the inadvertent removal of pressure-retaining components of a valve caused the release of 164,000 pounds of an acetic acid mixture, killing two contract workers. Additionally, one other contract worker and one company employee were seriously injured. The facility’s property damage, including loss of use from the incident, was estimated to be $40 million.

2 dead, 42 patients treated after leak at LyondellBasell facility in La Porte

CSB Chairperson Steve Owens said, "As this tragic incident shows, even a simple task can turn deadly if it is not performed properly. There have been similar incidents around the country involving plug valves being inadvertently taken apart when removing connected equipment. It is time to improve the design of these valves and take other protective actions, such as signage and training, before more workers are killed or injured."

The CSB’s report chronicles how, in the days leading up to the incident, an operation's technician discovered a small leak on methanol piping upstream of the unit’s acetic acid reactor. Soon after the leak was discovered, the shutdown of an adjacent unit required the acetic acid unit to also shut down. LyondellBasell decided to use the shutdown opportunity to repair the leak and have contractors at the facility perform the work. To isolate the piping, company personnel chose to use the plug valve located between the leaking pipe and the nearby acetic acid reactor. A plan was developed to remove the actuator which was connected to the plug valve.

Officials with LyondellBasell and the Harris County Fire Marshal's Office provide an update on a leak that occurred at the La Porte facility on Tuesday evening.

The contractor work crew began removing bolts that they believed were necessary to take off the actuator. The crew was not aware, however, that the bolts they removed actually secured the pressure-retaining valve cover in place. The plug ejected from the valve, releasing 164,000 pounds of an extremely hot acetic acid mixture which was 238 degrees Fahrenheit. The two fatally injured contractors were sprayed by the hot acetic acid and inhaled its toxic fumes. In addition, two other workers were seriously injured, and 29 employees working in an adjacent unit were transported to medical facilities for further evaluation and treatment.

The CSB’s report discusses two key safety issues.

CSB Investigator-in-Charge Harold Griffin said, "This was a tragic accident. The CSB’s recommendations seek to address current safety gaps and make sure that a similar incident does not occur. With the understanding of the changes that need to be made, this type of incident is very preventable."

The CSB’s report issues recommendations to LyondellBasell, the contractor – Turn2 Specialty Companies, the American Society of Mechanical Engineers, the American Petroleum Institute, and the Valve Manufacturers Association of America.

The recommendations seek to address gaps in equipment design and labeling, procedures, communication of past incidents, and worker training.


The CSB is an independent federal agency charged with investigating incidents and hazards that result, or may result, in the catastrophic release of extremely hazardous substances. The agency’s core mission activities include conducting incident investigations; formulating preventive or mitigative recommendations based on investigation findings and advocating for their implementation; issuing reports containing the findings, conclusions, and recommendations arising from incident investigations; and conducting studies on chemical hazards.

The agency's board members are appointed by the president subject to Senate confirmation. The Board does not issue citations or fines but makes safety recommendations to companies, industry organizations, labor groups, and regulatory agencies such as OSHA and EPA.

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PublishedLa Porte, Texas2 dead, 42 patients treated after leak at LyondellBasell facility in La PorteValve Design to Prevent Human Error:Providing Workers with Conditions, Procedures, and Training to Safely Conduct Work.DOWNLOAD THE FOX 26 HOUSTON APP BY CLICKING HERE