A crew was abandoning a main gas line for a customer. The injured employee was preparing to weld endcaps on the main. To do so, he was installing temporary expandable plugs on the north and south sides of the cutout in the gas main. As he was putting the plug on the south side, the plug from the north side was discharged from the pipe, contacting the employee s left hand and forearm. The employee sustained compound fractures to his forearm and contusions to his hand. The employee was hospitalized and required surgery.