Engineering Design & Testing Corp. Releases Preliminary Findings on Explosion at U. S. Steel Clairton Coke Works

Windsor, Conn. (October 15, 2025) - Engineering Design & Testing Corp. (EDT) was retained by U. S. Steel to conduct an independent investigation into the cause of the explosion that took place on August 11, 2025, at the U. S. Steel Clairton Coke Works in Clairton, Pennsylvania. Thomas D. Traubert, P.E., Vice President and Chief Engineer with EDT, conducted the investigation, which is on-going. The explosion took place in the 13-14 Coke Battery transfer area when an 18-inch cast iron valve ruptured, releasing flammable coke oven gas, which subsequently exploded. The valve was originally manufactured in 1953 and underwent refurbishment approximately ten years ago. Damage to other valves at 13-14 Coke Battery was determined to have resulted from the explosion. At the time that the valve ruptured, U. S. Steel employees and employees of MPW Industrial Services were opening and closing the valve to ensure proper operation in advance of planned maintenance activities.

As part of the valve opening and closing work, water at a high pressure was introduced into the valve in order to flush accumulated deposits. A sealed cavity inside the body of the valve filled with high-pressure flush water in excess of the pressure rating of the valve. This resulted in a sudden and complete rupture of the valve body, releasing combustible coke oven gas. The coke oven gas accumulated in the transfer area basement and exploded when it reached an ignition source at the adjacent 14 Battery.

Mr. Traubert reviewed U. S. Steel’s procedures for maintaining valves at the Clairton Facility as part of his investigation. Previously, low pressure (less than 10 psi) steam had been used to clean the valves. He determined that U. S. Steel did not have a specific procedure addressing the use of high-pressure water to flush valves. U. S. Steel does have an established Management of Change procedure that should have been used to evaluate the change from low pressure steam to high pressure water.

The investigation is on-going pending future testing as well as review of additional information as it becomes available.

Engineering Design & Testing Corp (EDT) is a forensic consulting firm serving all 50 states, providing multidiscipline services to insurance, legal and industrial clients. Engineers at EDT conduct root cause forensic investigations as well as damage evaluations in the industrial, commercial and residential areas. Mr. Traubert is a registered professional engineer with over 40 years of experience in the petrochemical, power and steel industries, with the past 30 years spent conducting forensic investigations of incidents in the petrochemical, steel, power and heavy manufacturing industries. Mr. Traubert has significant experience with the coke production process, including at U. S. Steel Clairton Coke Works.