scope:

This standard covers the preparation of buttwelding ends of pipe, valves, welding neck flanges, and pipe fittings, but is equally applicable to other piping components which are connected into the piping system by butt welding.

Materials of piping components for which these welding ends are primarily intended are carbon and alloy steels. They may also be used for nonferrous materials, upon satisfactory qualification of the welding procedures for the particular material.

This standard includes requirements for reentrant shapes for heavy wall ends, welding bevel profiles, inside contours for joints made with or without bachgrings, and internal end machining dimensions with their tolerances. The preparation for backing rings, if any, must be specified in ordering material to this standard.

This standard covers welding and preparation for four general types of joints, but does not prescribe specific types of welding processes nor procedures.

The four types of joints are those using:

a) no backing rings

b) split or noncontinuous backing rings

c) solid or continuous backing rings

d) consumable insert rings. 

This standard also covers welding end preparations for Gas Tungsten Arc Welding (GTAW) of the root pass