Abstract: Employees #1 and #2 were attempting to test fire the pilot light on a boiler that was approximately 18 feet long by 8 1/2 feet in diameter. Employee #1 was working on the left side of the blower (when standing in front looking at the boiler). Employee #2 was in front of the blower looking into the sight glass to verify the pilot ignition. When the explosion occurred, the front and rear doors were blown off the boiler. The left front door struck and killed Employee #1. Employee #2 was uninjured because he was protected by the blower. Investigation determined that the safety valve was faulty and had permitted gas to enter the boiler (maximum air and gas for approximately 75 seconds prior to the explosion). In addition, the control panel was improperly wired. Malfunctioning, the control panel turned on the gas when the blowers were turned on. The area where the work was being done was referred to as the test pit. The area was within the common area of the shop and was not isolated from the other work area in any way.