Abstract: At approximately 7:25 p.m. on August 15, 1991, Employee #1 and a coworker were assigned a work order to modify the drain line for an experimental incinerator burn. This required removal of 3/4 in. line (8 ft 3 in. long) and fitting. When both men applied pressure to the pipe, the valve up-line broke, allowing liquid and gas to strike Employee #1. Employee #1 was struck by waste products containing hydrofluoric acid. He inhaled the chemicals and absorbed them on his forehead, face, ear, neck, shoulder, and arms. He died eventually of anterior wall myocardial infarction. They were working on a work platform 2 to 2 1/2 ft above the concrete pad. Only one valve was closed between the active line and the work area. No lockout/tagout was noted on adjacent valves.