Chemical Safety Board: U.S. Steel
Clairton Works Facility
The Chemical Safety Board has just released an interim Investigation Update for the explosion that took place in August 2025 at the U.S. Steel Clairton Coke Works.
One of its recommendations reads as follows,
Conduct a siting evaluation for all occupied and potentially occupied buildings at the Clairton Coke Works facility. Utilize the guidance contained in the Center for Chemical Process Safety’s Guidelines for Evaluating Process Plant Buildings for External Explosions, Fires, and Toxic Releases, the American Petroleum Institute’s Recommended Practices 752, 753, and 756, and other industry good practice guidance documents.
This recommendation focuses on consequences to people, not on the initiating failure mechanism. The incident involved both U.S. Steel personnel and contractor personnel, which makes occupied-building and portable-building exposure a central issue. A siting evaluation is therefore a practical way to reduce future loss of life, regardless of the specific initiating cause of this specific explosion.
In this post we provide a brief overview of each of these API standards. We then review them in the context of this accident using the 20 elements of process safety published by the CCPS (Center for Chemical Process Safety).
In all cases it is important to distinguish between facility siting analysis (risk to occupants given scenarios) versus building design and hardening (mitigation measures).
The Incident
The following is their summary of the event.
On August 11, 2025, an explosion occurred at the U.S. Steel Clairton Coke Works facility in Clairton, Pennsylvania.
The explosion fatally injured two U.S. Steel employees. Four U.S. Steel employees and one Veolia Water North America Operating Services, LLC (Veolia) employee were seriously injured. Six other workers sustained injuries that did not require inpatient hospitalization. Of these six, five were U.S. Steel employees and one was an MPW Industrial Services, Inc. (MPW) employee.