Abstract: At approximately 4:15 p.m. on January 19, 1991, Employees #1 through #7 were working at a refinery, pulling a blind out of a 24 in. transfer line between a crude oil heater and an atmospheric tower. The burners on the side of the crude heater opposite the transfer lines were on, but pinched back to the pilot setting. The atmospheric tower was left full of hydrocarbon product. Nitrogen was pumped into the transfer line through a bleeder on the tower side of the blind. All of this was done at the start of the project; pulling the blind was the last task. When the blind was opened, the nitrogen flowed out, followed by hydrocarbon vapors from the tower. The vapors were pulled through the heater and ignited by the pilot light. There was an explosion inside the heater that ignited the vapors outside, resulting in a second explosion. Employees #1 through #7 were hospitalized for burns; Employee #4 died that night as a result of his injuries. Three of the employees worked for the refinery; the remaining four worked for a subcontractor.