1.1 This specification covers wrought carbon steel and alloy steel fittings of seamless and welded construction, covered by the latest revision of ASME B16.9, ASME B16.11, MSS-SP-79, MSS-SP-83, and MSS-SP-95. Fittings differing from these ASME and MSS This specification covers wrought carbon steel and alloy steel pipe fittings of seamless and welded construction for use in pressure piping and pressure vessel service at low temperatures. Materials shall consist of forgings, bars, plates, seamless or