This specification covers wrought high-strength low-alloy butt-welding steel fittings of seamless and electric fusion-welded construction for applications in high-pressure gas and oil transmission and distribution systems. Starting materials shall consist of plate, sheet, forgings, forging quality bar, and seamless or fusion-welded tubular products with filler metal added. Materials shall be heat treated by normalizing, quenching, and tempering or stress relieving. Specimens shall conform to required values of chemical composition and mechanical properties, namely: yield strength, tensile strength, elongation, notch toughness, and hardness. This specification does not require hydrostatic testing.

1.1 This specification covers wrought high-strength ferritic steel butt-welding fittings of seamless and electric fusion-welded construction covered by the latest revisions of ASME B16.9 and MSS-SP-75. Butt-welding fittings differing from these ASME and MSS standards shall be furnished in accordance with Supplementary Requirement S58 of Specification A960/A960M. These fittings are for use in high-pressure gas and oil transmission and distribution systems.

1.2 Optional supplementary requirements are provided for fittings when a greater degree of examination is desired. One or more of the supplementary requirements may be specified in the order.

1.3 This specification does not cover cast-welding fittings or fittings machined from castings.

1.4 The values stated in either SI units or inch-pound units are to be regarded separately as standard. Within the text, the SI units are shown in brackets. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard. Unless the order specifies the applicable “M” specification designation (SI units), the material shall be furnished to inch-pound units.