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 says preparations for a routine maintenance task may have led to an explosion at a U.S. Steel coal-processing plant near Pittsburgh that left two dead, sent 10 to hospitals and damaged part of the sprawling facility.