American Society for Testing and Materials (ASTM). Current edition approved Nov. 1, 2010. Published December 2010. Originally approved in 1958. Last previous edition approved in 2010 as A420/A420M–10. 6 p. This specification covers wrought carbon steel and alloy steel fittings of seamless and welded construction, covered by the latest revision of ASME B 16.9, ASME B 16.11, MSS-SP-79, MSS-SP-83, and MSS-SP-95. Fittings differing from these ASME and MSS standards shall be furnished in accordance with Supplementary Requirement S58 of Specification A 960/A 960M. These fittings are for use in pressure piping and pressure vessel service at low temperatures.