The preliminary findings say how the company believes the explosion occurred. A union statement cautioned the investigation is in its early stages.

The deadly explosion at Clairton Coke Works near Pittsburgh occurred when a gas valve was flushed before planned maintenance, ...

The company released its preliminary findings from an investigation into Monday’s explosion that killed two workers.

A gas valve failure during maintenance work may have led to the fatal explosion at the U.S. Steel Clairton plant in ...

U.S. Steel says preparations for a routine maintenance task may have led to an explosion at a U.S. Steel coal-processing ...

"Pressure built inside the valve, leading to valve failure and coke oven gas filling the area and ultimately exploding when ...

Flushing of a gas valve made during maintenance preparation may have led to the deadly explosion at the U.S. Steel Clairton ...

The explosion happened when workers were flushing a gas valve in preparation for maintenance on two of the plant's coke oven ...

U.S. Steel released preliminary findings about the potential cause of the deadly explosion at U.S. Steel Clairton Coke Works ...