Repairing Clairton, however, could be expensive, an investigation into the explosion could turn up more problems, and an official from the United Steelworkers union said it’s a constant struggle to get U.S. Steel to invest in its plants.

The deadly explosion at Clairton Coke Works near Pittsburgh occurred when a gas valve was flushed before planned maintenance, U.S. Steel said in preliminary findings.

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