The U.S. Chemical Safety and Hazard Investigation Board (CSB) released its final report on the July 27, 2021, fatal acetic acid release at the LyondellBasell La Porte Complex in La Porte, Texas.
CSB found that the pressure retaining components of a valve were inadvertently removed, which released 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.
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.”
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The report chronicles how, in the days leading up to the incident, an operations technician discovered a small leak on methanol piping upstream of the unit’s acetic acid reactor. Soon after the leak was discovered, an adjacent unit’s shutdown required the acetic acid unit to also shut down. LyondellBasell used the shutdown as an opportunity to repair the leak using contractors at the facility perform the work.
To isolate the piping, company personnel used the plug valve located between the leaking pipe and the nearby acetic acid reactor. They planned to remove the actuator, which was connected to the plug valve.
The contractor 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.
Valve design to prevent human error: Over the course of its investigation the CSB identified four similar incidents where pressure-retaining components of a plug valve were removed while attempting to remove equipment. The recurrence of these types of incidents points to the need to further re-design plug valves so that it is more difficult to remove pressure-retaining components while attempting to remove actuating equipment.
Providing workers with conditions, procedures, and training to safely conduct work. The CSB found that both the company and the contractor considered the removal of the actuator a simple task and did not provide the work crew with any sort of procedure or training. Nor did they adequately assess the potential risk of the operation prior to commencing work.
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 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 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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