The union vice president at U.S. Steel Clairton Coke Works is shedding new light on what led to the deadly explosion and the active effort to save the damaged batteries.

U.S. Steel shared that preliminary findings indicate that pressure building inside a gas valve led to its failure. Richard Tikey, the vice president of USW Local 1557, said as he understands it, steelworkers "significantly overpressurized" the valve with water as they were flushing it ahead of planned maintenance, causing the valve to split, releasing gas that would eventually ignite. The exact cause of the explosion is still under investigation.

The valve itself was last replaced in 2015, Tikey said. He does not believe the explosion was due to old equipment.

Since the explosion on Aug. 11, crews have been worki

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