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CSB says valve-design flaws and missing procedures led to fatal acetic-acid release at LyondellBasell La Porte plant
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Summary
The U.S. Chemical Safety Board found design vulnerabilities in plug valves and failures in procedures, training and contractor oversight led to a July 27, 2021 acetic-acid release at LyondellBasell's La Porte complex that sprayed three contract workers and killed two; the CSB recommended standards changes and company policy updates.
The U.S. Chemical Safety and Hazard Investigation Board (CSB) concluded that a July 27, 2021 release of roughly 164,000 pounds of acetic acid mixture at the LyondellBasell complex in La Porte, Texas resulted from valve-design vulnerabilities and failures in procedures, training and contractor oversight, the agency reported.
The incident occurred when a Turn 2 Specialty Companies crew removing an actuator from a plug valve inadvertently removed pressure-retaining fasteners and, after using a tool on a stuck coupler, caused the reactor's contents to erupt through the valve, the CSB said. The release sprayed three contract workers; two were fatally injured and the third was seriously hurt. Twenty-nine other people sought medical treatment.
The CSB identified two primary safety issues. First, some plug valves can be disassembled in ways that make it possible to remove pressure-retaining components by mistake; the CSB pointed to at least four prior serious incidents with the same failure mode. Second, the board found that LyondellBasell did not perform a thorough risk assessment for the actuator-removal task, had no written procedure for removing the actuator, and did not verify or train the contractor crew.
"Had LyondellBasell performed a risk assessment to ensure safeguards were in place during the actuator removal, as well as provided the Turn 2 work crew with written procedures, proper training, and oversight, this incident could have been prevented," the CSB report states.
The board recommended near-term steps and longer-term design changes. As an immediate measure, the CSB urged facilities to clearly mark pressure-retaining components on existing plug valves (for example, with color-coding and warning signs) so workers can identify them. For a long-term fix, the CSB recommended that standards organizations revise plug-valve design standards to require designs that make inadvertent removal of pressure-retaining components very difficult.
Specifically, the CSB recommended that the American Society of Mechanical Engineers and the American Petroleum Institute revise their standards to require marking of existing pressure-retaining components and to require that new plug valves be designed to prevent accidental removal of those components. The board also recommended that LyondellBasell update company policies to require written procedures for actuator removal and to verify that contractors are competent, trained and qualified before permitting the work to proceed.
A CSB speaker summarized the safety message: "It is time to improve the design of plug valves and take other protective actions, such as ensuring that clear markings are visible on all existing plug valve pressure-retaining components and workers are properly trained before conducting maintenance." The CSB directed viewers to csb.gov for more information.
Next steps: the CSB has issued its recommendations to standards bodies and the company; the transcript does not record whether or when ASME, API or LyondellBasell responded or acted on the recommendations.
