This specification covers wrought welding fittings for pressure piping, factory-made from nickel and nickel alloys. Threaded fittings as covered in ASME B16.11 are also covered by this specification. The term welding applies to butt-welding or socket-welding parts such as 45 and 90? elbows, 180? bends, caps, tees, reducers, lap-joint stub ends, and other types, as covered by ASME B16.9, ASME B16.11, ASME B16.28, MSS SP-43, MSS SP-95, and MSS SP-97. Class WP fittings are those manufactured to the requirements of ASME B16.9, B16.11, or B16.28. Class CR fittings are those manufactured to the requirements of MSS SP-43. This specification does not apply to cast welding fittings. Optional supplementary requirements are provided for fittings where a greater degree of examination is desired. These supplementary requirements call for additional tests. When desired, one or more of these may be specified in the order. The values stated in inch-pound units are to be regarded as the standard. The values given in parentheses are for information only.