A frozen air line and a frozen gas line were to blame for the explosion Friday at the Tonawanda Coke plant, the company explained in a statement released Wednesday night.
“The combination of simultaneous blockages caused a higher-than-usual buildup of pressure of coke oven gas in the manifold on the south side of the facility’s coke oven battery,” the company reported.
“The buildup… resulted in a disk rupture on a manifold underneath the coke oven battery at approximately 11:50 a.m.,” the statement added. “One minute later, the coke oven gas in the confined area underneath the battery combusted, resulting in an explosion.”
The statement noted that the explosion set off “a small fire,” which was extinguished in about 12 minutes “by trained on-site operators using both steam and water.”
The company said that damage was limited to some equipment and a few “nonstructural” brick walls.
The statement added that no one was injured.
Tonawanda Coke has been criticized for not allowing volunteer firefighters into the plant and for not providing an immediate explanation following the explosion.
The federal Occupational Safety and Health Administration is reported to be looking into the incident.
The company blamed the extreme cold weather for causing the lines to freeze. Temperatures had hit zero, with wind chills of minus 20, before rising to the low 30s last Thursday and Friday.
The company noted that, after analysis of the incident, several steps are being taken to improve monitoring and reduce the risk of lines freezing again.
The company added that it has submitted detailed reports about the explosion to the U.S. Environmental Protection Agency, the state Department of Environmental Conservation, the state Emergency Response Committee, local fire officials and OSHA.