CSB Urges Process Safety Management Improvements in New Final Report
Insufficient process safety management systems contributed to the fatal explosion and eruption at a liquid nitriding facility in Tennessee in May 2024, the U.S. Chemical Safety and Investigation Board has found. The results of CSB’s investigation of the incident are detailed in a final report (PDF) that was released last month. Treating metal parts in the liquid nitriding process at the Techniques Surfaces USA (TS USA) facility involves a reaction to harden the surface of the metal, the report explains. According to CSB, the explosion happened while workers were processing rollers with cavities. A roller cavity containing water was introduced to an 800 F oxidizing salt bath, where the hot salt caused the water in the cavity of the roller to expand and boil. This led to a steam explosion and an eruption of molten salt, which engulfed and fatally injured a line operator at the facility. The incident also caused more than $1 million in property damage and shut down the facility for about eight months.
CSB’s investigation found that TS USA lacked awareness of the accumulation hazards associated with the rollers with cavities. The agency also found that the facility and its parent company, HEF Groupe, did not have robust process safety management systems, as the systems in place did not include adequate procedures, training, hazard analyses, or incident investigations.
“Also contributing to the incident was HEF Groupe’s ineffective corporate governance and safety knowledge management, which did not ensure that critical safety information was communicated and accessible to all TS USA facilities, including details of prior safety incidents and the results of those investigations,” the CSB report concludes.
In addition to installing physical barriers around molten salt baths to protect workers from hazardous releases at all locations where liquid nitriding occurs, CSB recommends that TS USA implement a comprehensive safety management system that incorporates industry standards, including a hazard analysis program for assessing the nitriding process. The agency report also describes “key lessons” for the industry. For example, CSB urges companies in the industry to incorporate inherently safer design concepts into hazard analyses, which the agency says will help “ensure that there are effective and reliable controls to protect employees from process hazards.”
For more information, see CSB’s news release or download the final report (PDF).
