Butt welding metal pipes - using internal and external ceramic rings to prevent bulges or flash at the joint

摘要

Hollow metal profiles, esp. tubes or pipes, are butt welded by heating the entire periphery of the mating ends and pressing the two tubes together. Before welding, a hollow liner or cup, which does not bond to the tubes, is placed inside the tubes at the joint surface; and the outside dia. of the cup is slightly smaller than the bore of the two tubes being welded. During the welding process, the cup is continuously moved slowly along the bore of the tubes by means of a cable pulling the cup axially in the bore. A ring which does not react with the metal tubes is pref. located on the outside of the butt joint, the bore of the ring being slightly larger than the outside dia. of the tubes. For the welding of pipe elbows, the cup is pref. assembled from three or more segments, or is grooved so it can easily be fractured after welding.