Abstract: At approximately 4:45 p.m. on April 22, 1997, Employee #1, an aniline operator with one month of experience, was removing retaining bolts from the head of a waste water process filter casing. The filter casing was under pressure and, when enough retaining bolts had been removed, the head of the casing came flying off the vessel. It stuck Employee #1 on the head and chest, and carried him back approximately 5 to 10 ft, where he struck a support structure. He was killed. The accident was the result of Employee #1 failing to relieve the pressure contained in the vessel after he had pressurized the system to blow it down.