Abstract: An apparatus and method for capping a burning or blown out oil or gas well are disclosed. A pipe is placed over a flange and casing on a wellhead and welded thereto using thermite welding. The thermite reaction occurs in one or more crucibles mounted to the pipe. Graphite feeders direct the molten metal produced by the reaction into apertures near the bottom of the central pipe. The feeders join the pipe at an angle such that the molten metal flows into the annular space between the interior of the pipe and the wellhead structure in a generally circular flow pattern. A malleable clamp to conform to the configuration of the pipe and flange is provided to hold the pipe in place over the flange and act as a mold for the molten metal during the welding process. After the weld has formed, a valve in the pipe is closed, which simultaneously shuts off the flow of oil and extinguishes the fire by depriving it of oil, its fuel.