Abstract: The present invention provides a welding apparatus for forming a weld joint between abutting ends of first and second tubular members. The welding apparatus includes a housing having first and second sides defining an interior therebetween. The welding apparatus includes a welding electrode movably mounted within the interior of the housing and projecting toward the abutting ends of the first and second tubular members to thereby define an arc gap between the electrode and the abutting ends. The welding apparatus includes an electrical source for supplying welding energy to the welding electrode and a pressurized-gas source for supplying inert gas to the arc gap. The welding apparatus includes a chuck assembly secured to the first side of the housing and having a plurality of chuck jaws for frictionally engaging the surface of the first tubular member to thereby secure the abutting end of the first tubular member within the interior of the housing adjacent the welding electrode.

Abstract: An elastomeric mandrel has a shallow groove around the outer diameter. A woven sleeve of ceramic fiber surrounds the mandrel; which in turn is covered with a woven sleeve of fiberglass. The mandrel with coverings is inserted into tubing to be joined by welding with the shallow groove positioned under the joint. The mandrel is diametrically expanded by means located outside of the tubing to press the coverings against the inside of the tubing during time of welding, and the height of the weld underbead is controlled by the groove in the mandrel acting as a mold.