Inspection Detail

Inspection: 107567018 - U. S. Contractors

Inspection Information - Office: Houston South Area Office

Investigation Summary

On September 15, 1992, during the day shift, the steam distillate was found to contain high levels of ACN. The source of the ACN was the reboiler (DE-708A). Because the other reboiler (DE-708B) had already been taken out of service, operations management decided to shut down the BEU at approximately 10:30 a.m. The first step of the shut down involved redirecting the butadiene product to the "off-spec" tank and placing the solvent loop in a recycle mode. At approximately 12:30 p.m. the compressor serving the stripper (T705) was being isolated. Before completing these two processes, the employees were directed by the supervisor to isolate the reboiler (DE-708A). Two operators, Employees #1 and #2, and the shift foreman, Employee #3, climbed up onto the platforms and began to isolate the reboiler. Employee #1 had closed the steam control valve to the reboiler and then stopped the lower level and began to close the block valve on the liquid leg. Employee #2 was attempting to close the steam block valve but had to wait for help from Employee #1 because it was too hard to turn. Employees #1 and #2 heard a hammering sound but simply attributed the sound to maintenance men in the area, Employees #4 , #5, and #6, knocking on something. Hearing the same hammering sound, Employees #4 through #6 thought the same of Employees #1 through #3. One of the operators and Employee #3 closed the vapor line block valve. Again a hammering sound was heard. The operator, thinking a PSV was releasing, reopened the vapor line valve. There was a loud noise and a cloud of yellow smoke appeared. Hot liquid from the reboiler sprayed Employees #1 through #6, knocking one employee over the rail to the lower level. There was no fire, only a lot of smoke. All six employees were rescued, and then transported and admitted to the hospital.

Keywords: BOILER, VALVE, BURN, MAINTENANCE, VAPOR, CONSTRUCTION, FALL, ACCIDENTAL DISCHARGE