Inspection Detail

Inspection: 126587047 - Elf Atochem North America, Inc.

Inspection Information - Office: Minnesota Department Of Labor And Industry

Investigation Summary

The employer is a manufacturer of epoxidized soybean oil that is used to make flexible plastic from refined soybean oil. Food grade vegetable oil is fused with hydrogen peroxide, resulting in epoxidized oil. After the main reaction process, the product goes to a vacuum vessel centrifuge. Oil from the centrifuge then moves to a stripper vessel where steam removes water, acetic acid, and hydrogen peroxide product remnants. The steam from the stripper is injected using a vacuum and, in turn, condenses back into a receiving pot after it has moved to an overhead condenser or heat exchanger/converter located above the stripper. From this condenser, residual acids are stripped out and moved to the acid receiver, a neutralization tank and recovery site for acetic acid residue. An acidic water line goes from the condenser/ converter to the receiver. Employee #3 and a coworker were checking steam traps on the first floor by tapping on them, but they were not removing any of the condensate. They got two new traps ready as replacements after a batch in the vessel was processed. Condensate was drained out of the steam lines and after the drain valves were closed, the traps were apparently working and the stripper vessel's temperature began to rise to its set point. Employees #1 and #2 went to the second floor to check the stripper. Employee #2 was looking through a sightglass atop the stripper to ensure that excessive water was not coming in and to check what was happening in the stripper. All appeared normal when suddenly the acidic water line near the ceiling, which contained water, acetic acid, and hydrogen peroxide, exploded, blowing out the second story wall. Employee #1 was found dead on an adjacent roof area. He had been walking toward the receiver area near the south wall to turn on the steam valves, but it is not known if he had reached them before the explosion occurred. Employee #2 was about 20 ft away looking into the stripper sightglass; he was struck by flying debris and exposed to excessive noise. Employee #3, who was walking 8 ft away from the bottom portion of the stripper on the first floor below, also suffered injuries from flying debris. Both were hospitalized.

Keywords: MAINTENANCE, PRESSURE VESSEL, WORK RULES, EXPLOSION, STRUCK BY, FLYING OBJECT