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What caused Clairton Coke Works explosions? Preliminary findings revealed

Explore the recent preliminary findings that reveal the cause behind the devastating explosion at Clairton Coke Works.
posted by Vaishnavi Sah
Monday 8/18/2025 at 3:25PM EDT
  • LOS ANGELES, CALIFORNIA - JANUARY 07: People watch the smoke and flames from the Palisades Fire in the Pacific Palisades neighborhood on January 07, 2025 in Los Angeles, California. Fueled by intense Santa Ana Winds, the Palisades Fire has grown to over 2,900 acres and 30,000 people have been ordered to evacuate while a second fire has emerged near Eaton Canyon. (Photo by Tiffany Rose/Getty Images)
    LOS ANGELES, CALIFORNIA - JANUARY 07: People watch the smoke and flames from the Palisades Fire in the Pacific Palisades neighborhood on January 07, 2025 in Los Angeles, California. Fueled by intense Santa Ana Winds, the Palisades Fire has grown to over 2,900 acres and 30,000 people have been ordered to evacuate while a second fire has emerged near Eaton Canyon. (Photo by Tiffany Rose/Getty Images)

    Recent preliminary findings have revealed the potential cause of the deadly explosion at U.S. Steel Clairton Coke Works in Allegheny County, Pennsylvania.. Around 11 a.m. on Monday, August 11, the explosion at the 392-acre Clairton plant claimed the lives of two workers, Timothy Quinn, 39, and Steven Menefee, 52. Ten others were hospitalized, while others sustained minor injuries.

    In preliminary findings released on August 15, U.S. Steel stated on its official website that the United Steelworkers (USW) and third-party experts have been working diligently to review video footage and interview employees. The initial investigation suggests that the explosion occurred while flushing a gas valve, in preparation for planned maintenance. As pressure built up inside the valve, it led to valve failure, and coke oven gas filled the area, ultimately “exploding when finding an ignition source.”

    “We want to reinforce that this investigation is in its early stages, and we will provide more information when we can. Our focus remains on our employees and their families during this difficult time,” the report added.

    Reacting to the preliminary findings on Friday, Clairton's Mayor Rich Lattanzi stated that he thought "something like this would take two to four to five months for it to unfold."

    "I'm thinking what they found is a smoking gun," Lattanzi added.  

    After the blast, U.S. Steel released a statement claiming that the explosion specifically occurred at coke oven batteries 13 and 14.

    “Emergency teams were immediately dispatched to the scene. Our top priority is the safety and wellbeing of our employees and the environment. We are working closely with relevant authorities to investigate the cause of the incident and will provide additional updates as they become available. Nearly 1,300 dedicated men and women work at the Clairton Plant each day, performing their jobs with the utmost safety. During times like this, U. S. Steel employees come together to extend their love, prayers, and support to everyone affected,” the statement added.

    Clairton Coke Works has a history of explosions

    According to AP News, the Clairton Coke Works has previously experienced multiple explosions. For instance, a loud explosion at the plant on February 5, 2025, injured two workers. Subsequently, in June 2025, a breakdown in the plant led to three days of a strong rotten egg odor in the air around it due to elevated hydrogen sulfide emissions.

    Additionally, a fire on Christmas Eve in 2018 released high levels of sulfur dioxide into the air for weeks, which led to a lawsuit. An engineer for the environmental groups who sued claimed that the plant “found no indication that U.S. Steel has an effective, comprehensive maintenance program for the Clairton plant," and described the facility as “inherently dangerous because of the combination of its deficient maintenance and its defective design.”

    CNN cited an OSHA report, which stated that the last death at the factory occurred in 2014, when a worker "burned and died after falling into a trench." 

    The Clairton Coke Works, owned by US Steel, is the largest coking factory in North America, and produces 4.3 million tons of coke a year, per Reuters. 

    TOPICS: Clairton Coke Works