U.S. Steel Corp. has sued Power Piping Co., an Etna steamfitter, to recoup nearly $7 million in expenses the steelmaker claims it has incurred since an explosion in 2010 at the Clairton coke works.
The suit was filed Friday in Allegheny County Common Pleas Court.
U.S. Steel says it has spent more than $6.9 million in connection with the July 14, 2010, explosion in a section of the works known as "B battery" that injured numerous people.
Power Piping workers were trying to shut down the flow of volatile gas to clean a piece of equipment when the explosion occurred.
Five Power Piping employees have sued U.S. Steel.
An investigation by the U.S. Occupational Safety and Health Administration concluded that U.S. Steel's safety procedures failed to properly contain coke oven gas.
OSHA cited both U.S. Steel and Power Piping for various violations and fined them.
U.S. Steel contested its $143,500 fine. In a settlement earlier this month, the Department of Labor knocked the penalty down to $78,500.