Abstract: At approximately 8:00 p.m. on July 16, 1994, Employee #1, an operator in the alky unit of an oil refinery, was between the acid regeneration system and the neutralization system. The level in the rerun tower (part of the acid regeneration system) was controlled by an automatic level control valve (92LC0102), which allowed the stream to flow to the ASO neutralization system. A line break at a T just past this control valve occurred while Employee #1 was trying to remove a bull plug from a 3/4 in. bleeder pipe. Employee #1 told the stillman that he was trying to correct a blockage in the line. The method he was using was not a normal method commonly used by the operators interviewed, and according to the alky unit operators, the operation that Employee #1 was performing did not have written operating procedures. The bleeder pipe that broke from the T was approximately 17 in. long with the Durco valve about 4 in. from the break and about 10 in. from the break to another T containing a bull plug. Another bull plug was also on the end of the bleeder. The P and IDs did not show this configuration for this bleeder. Employee #1 was exposed to acid-soluble oil or ASO, which contains 5 to 20 percent HF. He suffered chemical burns and was killed.