Abstract: An electric utility maintenance worker had installed a 610-millimeter-diameter pipe extension onto a noncondensable gas line. The extension was installed to prevent the sludge and brine that was in the line from blowing on the employee as he was draining it. He had installed the extension hand tight. When the employee tried to open the valve with his right foot, nothing happened. He put more pressure on the valve handle with his right foot; and the contents of the pipe, at 690 to 965 kilopascals of pressure, were released all at once. The pipe extension, which had a 90-degree elbow on its open end, started spinning around, tightening itself onto the pipe. The spinning extension hit the employee on his left foot. When he shifted his weight to his right foot, the spinning pipe also hit that foot; and the employee fell to the ground. While he was on the ground, the still-spinning pipe hit his left forearm. The extension continued to spin until it tightened itself onto the gas line. The employee was hospitalized with four fractured toes on his left foot, fractures of the bones in the arch of his right foot, and a fractured right wrist.