This standard is issued the fixed designation A 420/A 420M; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript epsilon (e) indicates an editorial change since the last revision or reapproval.

1. Scope

1.1 This specification covers wrought carbon steel and alloy steel fittings of seamless and welded construction, covered by the latest revision of ANSI B 16.9, ANSI B16.11, ANSI B16.28, and MSS-SP-79. Fittings differing from these ANSI and MSSVF standards shall be furnished in accordance with Supplementary Requirement S6. These fittings are for use in pressure piping and pressure vessel service at low temperatures.
1.2 Optional supplementary requirements are provided for fittings where a greater degree of examination is desired. When desired, one or more of these supplementary requirements may be specified in the order.
1.3 This specification is expressed in both inch-pound units and in SI units. However, unless the order specifies the applicable “M” specification designation (SI units), the material shall be furnished to inch-pound units.
1.4 The values stated in either inch-pound units or SI units are to be regarded separately as standard. Within the text, the SI units are shown in brackets. The values stated in each system are not exact equivalents; therefore; each system must be used independently of the other. Combining values from the two systems may result in nonconformance with the specification.