Abstract: At approximately 8:40 p.m. on May 31, 2001, Employee #1, a maintenance mechanic, was at the lower deck furnace area. Employee #1 and a coworker were in the process of doing a post run maintenance procedure on ceramic furnace Number 72. Post run maintenance includes the removal of exhaust plumbing units located underneath the furnace by loosening and removing screws on the flanges, and wheeling the unit out to the wash down area for clean up. Process gases include MTS (Methyltrichlorosilane), hydrogen, and nitrogen as inert gas. By products of the reaction consisted of chlorine, hydrogen and silicone leave the furnace through the exhaust plumbing. Exhaust plumbing is at the bottom of the furnace located at the furnace lower deck area. After loosening and removing the fasteners, Employee #1 went to the bathroom for about five minutes and then came back to complete the removal process. While standing by the unit getting ready to pull it out, a violent pyrophoric reaction of the by products deposited in the pipe occurred causing an explosion and flash fire. Employee #1 suffered first and second degree burns to his left face, upper forearms, neck and upper body and was hospitalized.