A company’s failure to realize that welding work was being done near flammable materials was behind a fatal explosion, according to the U.S. Chemical Safety Board (CSB), which has released its final investigation report into the February 8, 2017, blast at the Packaging Corporation of America’s (PCA’s) DeRidder, Louisiana, pulp and paper mill. The incident killed three contract workers who were performing welding and grinding, referred to as “hot work,” above a tank that contained flammable materials. Seven others were injured.
The explosion at PCA occurred during the facility’s annual shutdown. On the day of the incident, contract workers were welding on water piping above and disconnected from a 100,000-gallon-capacity storage tank. The tank contained about ten feet of liquid, called “foul condensate.” The foul condensate was composed of mostly water, but also contained a floating layer of flammable hydrocarbons, in the form of residual turpentine and other sulfur-containing compounds. Under normal operations the atmosphere inside the foul condensate tank is not explosive.