Backing in the form of a ring, generally used in the welding of pipe. See STANDARD WELDING TERMS.
A backing ring helps maintain correct alignment of the pipe or tube ends during welding, and assures complete fusion to the root of the joint without the formation of slag, icicles, or spatter within the bore. The backing ring can be made from a strip of metal which is formed into a ring and fitted to the inside surface of a pipe or tube prior to welding. The ring should be substantially the same chemical composition as the pipe or tube to be welded.