Abstract: At 8:45 a.m. on April 1, 2002, Employee #1, a process engineer for a conduit and tubing manufacturer, was photographing the inside of a process Air Exhaust Valve (Switching Valve), which had experienced a fire earlier in the day. The Air Exhaust Valve is a manifold that consists of two valve plates on a horizontal shaft. The shaft was driven by a pneumatic cylinder, controlled by a Programmable Logic Controller. The valve was part of an air pollution control unit called the Roxidizer Model 20, manufactured by Tellkamp Systems, Inc. In addition to Employee # 1, various employees, including a maintenance foreman, several maintenance mechanics, an electrician, and the Manager of Engineering were involved with the simultaneous post fire assessment and repair of the equipment. Employee # 1 did not verify that the unit had been locked out and deenergized nor that air supplies had been shut off and bled down before accessing the system. Employee # 1 had his arm inside an access door of the Switching Valve, trying to determine if the inside of the Roxidizer had been damaged when the valve cycled, causing multiple fractures and torn tendons in his right forearm and wrist.