Final Report Issued By U.S. Chemical Safety Board On U.S. Steel Explosion That Killed Workers 

Safety at Work

The U.S. Chemical Safety and Hazard Investigative Board (CSB) released its final report on the fatal August 11, 2025, explosion at the U.S. Steel Clairton Coke Works plant in Clairton, Pa.  The incident occurred when toxic flammable coke oven gas was released and exploded – killing two workers, seriously injuring 11 others  and causing an estimated $52.5 million in property damage. 

“This deadly incident was the result of an ad hoc informal procedure, poor facility siting and an ineffective process safety management system at the Clairton plant. It should never have happened,’’ said Steve Owens, chairperson of the Chemical Safety Board. 

U.S. Steel has said the explosion happened when workers were flushing a gas valve with pressurized water in preparation for routine planned maintenance at the sprawling riverside industrial facility.  The valve ruptured under pressure and released combustible coke oven gas. 

The Occupational Safety and Health Administration previously fined the company a total of $118,214 and issued 10 citations. OHSA had said that U.S. Steel’s written procedures, practices and training to safely maintain equipment and flush the gas valve were incomplete, outdated and inadequate. 

The Chemical Board report recommended that U.S. Steel develop written procedures for washing valves with pressurized water in order to minimize the operation’s hazards. It also recommended that an industrial cleaning contractor which used a pump truck to apply pressurized water to the valve develop written policies and procedures for cleaning piping systems containing flammable or toxic gas, and train its workers in such operations. 

Chemical Safety Board member Sylvia Johnson said the blast “was the result of workers routinely performing a task incorrectly over a period of years until ultimately it led to a catastrophic explosion.’’ The valve that failed was more than 70 years old and made from cast iron, which the report said is widely recognized as brittle material. 

In light of the Chemical Board report, steelworkers marched through Pittsburgh streets Aug. 21 demanding better safety conditions. Backed by the blare of sober bagpipe ballads and Rage Against The Machine,  the workers  paraded back and forth from the USW headquarters on the Boulevard of the Allies to the Pittsburgh office of U.S. Sen. Dave McCormick in the Grant Building.  The group sought to present a petition to the Republican senator urging him to support the “Protecting America’s Workers Act,’’ a set of Democratic-backed bills that would expand Occupational Safety and Health Administration protections and hold employers criminally  liable for knowingly violating workplace safety standards. 

U.S. Sen. John Fetterman, McCormick’s Democratic counterpart, is already a cosponsor of the bill. 

According to the federal Bureau of Labor Statistics, 5,070 workers died from work-related injuries in 2024. 

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