In Wake of Fatal Explosion at Steel Plant, CSB Urges Siting Evaluations
In late December, the Chemical Safety and Hazard Investigation Board (CSB) issued two interim safety recommendations related to its investigation of a fatal explosion that occurred on Aug. 11, 2025, at U.S. Steel’s Clairton Coke Works facility in Clairton, Pennsylvania. Two U.S. Steel employees were killed, four additional employees and one contractor were seriously injured, and six other workers suffered relatively minor injuries after coke oven gas was released from process piping and ignited in the facility’s Battery 13/14 transfer area. While CSB’s investigation of the incident remains in its early stages, the agency says it has identified potential hazards requiring “immediate attention,” both of which concern the locations of buildings near hazardous processes. CSB’s interim recommendations aim to address these hazards.
CSB’s first recommendation is that U.S. Steel identify and assess the locations of all buildings at the facility that are currently occupied or may be occupied by workers using industry guidance such as the Center for Chemical Process Safety’s Guidelines for Evaluating Process Plant Buildings for External Explosions, Fires, and Toxic Releases and the American Petroleum Institute’s Recommended Practices 752, 753, and 756. Second, CSB urges U.S. Steel to address all safety risks identified during the siting evaluation in accordance with “accepted industry safety principles.”
The company has already rebuilt damaged piping in almost the same location and layout as it was prior to the explosion, as well as relocated the control room for Battery 13/14 to a site about 100 feet away, a CSB news release states. The agency’s investigation has determined that both of the fatally injured workers and two of the seriously injured workers were inside or near buildings in the area where the explosion occurred. Without a thorough facility siting evaluation, “it is not clear that U.S. Steel has chosen a safe location to relocate its workers,” according to CSB.
CSB has found that four other coke batteries operated by the Clairton Coke Works facility have workers occupying buildings near potentially hazardous processes. Facility siting evaluations at these locations "would identify and assess hazards that may exist in these other buildings as well," the agency states.
More information about the interim recommendations may be found in CSB’s news release. Additional findings and recommendations related to the 2025 explosion will be available when CSB’s final report is published.