ASME B16.25-1997

This Standard covers the preparation of buttwelding ends of piping components to be joined into a piping system by welding. It includes requirements for welding bevels, for external and internal shaping of heavy-wall components, and for preparation of internal ends (including dimensions and tolerances). Coverage includes preparation for joints with the following. (a) no backing rings; (b) split or noncontinuous backing rings; (c) solid or continuous backing rings; (d) consumable insert rings; (e) gas tungsten are welding (GTAW) of the root pass. Details of preparation for any backing ring must be specified in ordering the component.