A company’s internal confusion and lack of concern for safety caused the deaths of three workers and injuries to seven others last year at the Packaging Corporation of America (PCA) container board mill in DeRidder, La. In a report released today, the U.S. Chemical Safety & Hazard Investigation Board (CSB) urges that tanks holding liquids at atmospheric pressure, such as the one that exploded at PCA, be regulated. Alternatively, companies should voluntarily take adequate safety precautions, CSB says.
On Feb. 8, 2017, welders above a leaking 380,000 L waste tank likely provided a spark that set off an explosion. The tank flew over the top of a six-story building and landed 114 m away. The people who died were all contract workers conducting routine maintenance during an annual shutdown.
The welders were repairing water lines above a pulp waste tank that held a mix of water, sulfuric substances, and residual turpentine. Most of the turpentine had been stripped during manufacturing processes, and the waste tank was intended to hold only small amounts of the hydrocarbon.
But because of a company dispute over who was responsible for skimming and removing the residual turpentine, the tank instead held an unusually large amount of turpentine—a fact that the welders working above it did not know. Turpentine is immiscible in and less dense than water, so it separated to rest on top of the waste mixture.
Additionally, a crack in the tank allowed air to mix with flammable vapor in the tank. The crack also likely provided a pathway for vapor to extend between the tank and the welders working above, permitting a welder’s spark to ignite the tank contents.
“Hot work, such as welding, conducted around tanks containing flammable materials can be catastrophic,” says CSB chairperson Vanessa Allen Sutherland. “That is why it is so important for companies to effectively identify, evaluate, and control potential hazards prior to initiation of hot work.” CSB first identified atmospheric tanks as a potential hazard in 2002.
Sutherland reiterated a 2002 CSB recommendation issued to the Occupational Safety & Health Administration (OSHA) that the agency include atmospheric storage tanks under its process safety management (PSM) standards if the tanks are connected to a PSM-covered process, which would have included PCA’s tank. Sutherland also recommends that the pulp and paper industry apply PSM principles, even if not required by regulation.
For this accident, OSHA has proposed a fine of $63,375. The company is contesting OSHA’s findings.