The possible failure of a gas valve may have led to the deadly explosion at the Clairton Coke Works earlier this week, U.S. Steel said Friday, revealing the findings of its preliminary investigation.

The Pittsburgh-based steelmaker in a statement said Friday that the flushing was part of preparation for planned maintenance.

“Pressure built inside the valve, leading to valve failure and coke oven gas filling the area and ultimately exploding when finding an ignition source,” U.S. Steel spokeswoman Amanda Malkowski said in the statement.

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

The company said it’s working with th

See Full Page