Accident Description
On July 29, 2008, three workers died and a fourth was injured when an explosion occurred inside an 80-foot-tall storage tank at the Packaging Corporation of America (PCA) corrugated cardboard mill in Tomahawk, Wisconsin. The workers were on a catwalk above the tank and performing hot work (welding) at the time of the explosion. The storage tank held a mixture of recycled paper pulp and water which the CSB found decomposed to form flammable hydrogen.
Investigation Status
The CSB issued a hot work safety bulletin summarizing the key findings from the investigation at a news conference on March 4, 2010.