ANSI/ASME B16.25 Standard covers the preparation of butt welding ends of piping components to be joined into a piping system by welding. It includes requirements forwelding 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 arc welding (GTAW) of the root pass Details of preparation for any backing ring must be specified when ordering the component. ANSI/ASME B16.25 Standard applies to any metallic materials for which a welding procedure can be satisfactorily qualified, but does not prescribe specific welding processes or procedures. Unless otherwise specified by the purchaser, it does not apply towelding ends conforming to ASME B16.5, B16.9, or B16.47.

MSS SP-97 Standard Practice covers essential dimensions, finish, tolerances, testing, marking, material, and minimum strength requirements for 90 degree integrally reinforced forged branch outlet fittings of buttwelding, socket welding, and threaded types. Integrally Reinforced Forged Branch Outlet Fittings – Socket Welding, Threaded, and Buttwelding Ends. Fittings manufactured to this Standard Practice are designed to make a fully reinforced branch connection in accordance with applicable piping code requirements, when attached, at an opening in a run pipe by means of a full penetration weld. Fittings may be made to special dimensions, size, shape, tolerances, or of other wrought material by agreement between the manufacturer and the purchaser. MSS MSS(Manufacturers Standardization Society) is the only organization in the world dedicated exclusively to the technical needs of the valve and fittings industry. Standards and codes are written and revised by 25 technical committe