Abstract: A method for repairing metal pipe with dents includes steps of a) holding the pipe with first and second ends in position; b) dragging the mandrel through the pipe; and c) pushing out the dents from inside to an original level of the surface of the pipe. The cross-section of the mandrel has a substantially same cross-section of the hollow space of a undamaged pipe, and the outer surface of the major portion of the mandrel fits tightly to the inside of the undamaged pipe. The step of holding the pipe includes steps of a) guiding the pipe into a locking position; b) stopping the pipe along the direction of the axis of the pipe; and c) stopping the pipe along the perpendicular direction of the axis of the pipe.

Abstract: A method for repairing metal pipe with dents includes steps of a) holding the pipe with first and second ends in position; b) dragging the mandrel through the pipe; and c) pushing out the dents from inside to an original level of the surface of the pipe. The cross-section of the mandrel has a substantially same cross-section of the hollow space of a undamaged pipe, and the outer surface of the major portion of the mandrel fits tightly to the inside of the undamaged pipe. The step of holding the pipe includes steps of a) guiding the pipe into a locking position; b) stopping the pipe along the direction of the axis of the pipe; and c) stopping the pipe along the perpendicular direction of the axis of the pipe.

Abstract: A system for repairing a pipe damaged with dents includes a pipe holding device, a mandrel, a cable, and a winch. The pipe holding device is for holding the pipe in position. The mandrel, with a cross section and size adapted to be pulled through the interior of the pipe, has a first edge, a second edge, and a side surface. The cable has first and second ends, and the first end is detachably attached to the first edge of the mandrel. The winch is connected to the second end of the cable for winding up the cable. The mandrel is pulled by the winch with the cable and travels through the pipe to push out from inside and remove the dents on the surface of the pipe.