Board Calls for US Steel to Address Safety Issues as It Rebuilds Site of Fatal Explosion

The Chemical Safety and Hazard Investigation Board (CSB) has issued interim safety recommendations in connection with the agency’s ongoing investigation into the August 11, 2025, fatal explosion at U.S. Steel’s Clairton Coke Works facility in Pennsylvania.

Although the CSB’s investigation is in its early stages, the agency reported that it has “identified potentially unmitigated hazards for workers at Clairton Coke Works” that it believes “warrant immediate attention.” The CSB’s interim recommendations are intended to address these potential hazards.

The explosion occurred when coke oven gas was released from process piping in the Battery 13/14 transfer area at the facility and ignited. Two U.S. Steel employees were killed in the explosion, four additional employees and a contractor were seriously injured, and six other workers suffered non-hospitalization injuries. The explosion also severely damaged nearby structures.

“Even though our investigation into this terrible tragedy is ongoing, the CSB is issuing these initial recommendations to ensure that workers at the Clairton Coke Works facility are not put in harm’s way hereafter,’ CSB Chairperson Steve Owens said in releasing its recommendations.

The CSB wants U.S. Steel to perform a “thorough evaluation” of all buildings at the Clairton Coke Works facility to identify any “potential hazards to workers based on where the buildings are located.” The CSB found that both of the workers who were killed and two of the five workers who were seriously injured were inside or near buildings in the area where the explosion occurred. The CSB also has found that the occupied buildings in the transfer area were not capable of protecting occupants from explosion hazards.

According to the CSB, U.S. Steel already has rebuilt the damaged coke oven gas supply piping in almost the same location and layout as it was prior to the explosion. Although the company is relocating the control rooms for Battery 13/14 to a building approximately 100 feet away from the area, the CSB is concerned that that without a facility siting evaluation, it is not clear that the location U.S. Steel has chosen is a safe place to relocate its workers.

Fatal Explosion at 110-Year Old U.S. Steel’s Plant Raises Questions About Its Future

The CSB also found that the Clairton Coke Works facility operates four other coke batteries with personnel-occupied buildings located near potentially hazardous processes. The CSB is calling on U.S. Steel to reduce any safety risks identified in the facility siting evaluation, following accepted industry safety principles.

The Clairton Coke Works facility processes raw coal into coke, which is then used in making steel. The 392-acre facility is located about 15 miles outside of Pittsburgh and is considered the largest coking facility in North America. Nearly 1,300 employees work at the facility.

The explosion at the coal-processing plant raised questions about its future.

President Donald Trump approved the nearly $15 billion acquisition of U.S. Steel by Japanese steelmaker Nippon Steel. Prior to the tragedy, Nippon Steel had promised to invest in the plant. The size of that investment may have increased due to the explosion at the plat, which has experienced other accidents, as well as pollution fines and lawsuits.

The Trump Administration has also has postponed new hazardous air pollution requirements for coke plants like Clairton.

CSB said its final report will include additional findings and recommendations.

The CSB is a federal agency charged with investigating incidents relating to hazardous substances. The Trump Administration has signaled that it wants to eliminate the CSB, arguing it duplicates the work of other agencies including the Environmental Protection Agency and the Occupational Safety and Health Administration. The Administration’s 2026 budget recommends $0 funding for the CSB.

Photo: A portion of the Clairton Coke Works, a U.S. Steel plant, is seen Monday, Aug. 11, 2025 in Clairton, Pa. (AP Photo/Gene J. Puskar

Topics USA Training Development