June 29, 2023

Lack of Safety Procedures Led to Death of Contracted Worker, CSB Finds

On June 15, the U.S. Chemical Safety and Hazard Investigation Board published its final report (PDF) on a hydrogen chloride (HCl) release that led to a worker’s death in November 2020 at the Wacker Polysilicon North American facility in Charleston, Tennessee. According to CSB, Wacker’s lack of written maintenance procedures, procedures for controlling hazardous energy, and procedures for simultaneous operations, as well as the single means of exiting the affected area, contributed to the incident’s severity.

The report explains that seven contract workers were performing tasks on the fifth floor of an equipment access platform at the Wacker facility on Nov. 13, 2020. Three workers employed by one contracting firm were tasked with bolt torquing and wore full-body chemical-resistant suits. The remaining workers, employed by a different contractor, wore flame-resistant clothing as they insulated equipment. When one worker excessively tightened the bolts on a pipe containing HCl, the pipe cracked, releasing HCl onto the platform. HCl gas irritates the nose, throat, and larynx and causes coughing, choking, and dermatitis, according to the NIOSH Pocket Guide to Chemical Hazards.

The workers could not see the platform’s single staircase due to a white cloud formed by the released HCl. Three workers not wearing chemical-resistant suits attempted to escape by climbing down the side of the structure. All three fell to the ground, roughly 70 feet below—one was fatally injured, and two were seriously injured. The four workers who remained on the platform reached the ground via the staircase after the release stopped.

Although CSB determined that accidental over-tightening of the bolts directly caused the incident, “[b]oth the lack of written procedures and ineffective control of hazardous energy contributed the occurrence of the event,” said Deputy Investigator-in-Charge Tyler Nelson.

According to the report, Wacker did not have a written procedure for torquing bolts. Instead, the company relied on the manual provided by the pipe manufacturer, which did not provide torque requirements for the excessively tightened bolts. This lack of clarity led to the over-tightening of the bolts, fracturing of the pipe, and release of HCl.

CSB also found that Wacker did not require isolation of hazardous energy during torquing activities on pipes containing hazardous materials, so the company did not perform a risk analysis to determine whether these tasks could be done safely or attempt to mitigate the risk. Neither did Wacker have a policy for evaluating simultaneous operations involving two or more tasks occurring at the same time and place, resulting in unnecessary exposure of the workers not involved in the torquing task to HCl.

The report notes that Wacker employees had identified the need for a second exit from the equipment access platform three months before the incident, but Wacker had not acted on this recommendation. CSB found existing building code requirements inadequate for platforms used to access equipment containing hazardous materials.

As part of CSB’s recommendations for addressing these safety issues, the agency reiterated the need for OSHA to require facility owners and operators to coordinate simultaneous operations. CSB originally made this recommendation after its investigation of a fire at a paper mill that led to the deaths of two contracted workers who were also involved in simultaneous operations. CSB also recommends that the International Code Council and National Fire Protection Association address conditions requiring multiple means of exiting elevated structures in their building code requirements.

For more information, read CSB’s press release announcing the report’s publication.