This specification covers five grades of as-welded, wrought austenitic stainless steel fittings for low-pressure piping and for low and moderate temperatures and general corrosive service. The fittings shall be made from flat-rolled steel which shall be in the solution annealed condition. The fittings shall be formed by a hot or cold process and shall be welded by a shielded welding process with or without the addition of filler metal. Heat analysis and product analysis shall be performed where in the steel fittings shall conform to the required chemical compositions of carbon, manganese, phosphorus, sulfur, silicon, chromium, nickel, molybdenum, titanium, columbium, tantalum, and nitrogen. The steel materials shall also undergo mechanical tests and shall conform to the required values of tensile strength, yield strength, elongation, and hardness.

1.1 This specification covers five grades of as-welded, wrought austenitic stainless steel fittings for low-pressure piping and intended for low and moderate temperatures and general corrosive service. Users should note that certain corrosive conditions may restrict the use of one or more grades. For applications requiring a product that requires heat treatment or full pressure rating, refer to Specification A403/A403M. The term “fittings” applies to butt and socket welding parts such as 45° and 90° elbows, tees, reducers, wyes, laterals, crosses, and stub ends.

1.2 This specification covers as-welded fittings 3 through 48 in. [75 through 1225 mm] in outside diameter and in nominal wall thicknesses 0.062 through 0.500 in. [1.6 through 12.7 mm]. Table 1 and Table 2 list the common diameters and nominal thicknesses of fittings in this specification.

1.3 This specification does not apply to cast fittings. Cast austenitic steel fittings are covered by Specification A351/A351M.

1.4 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.

1.5 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.

1.6 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.

1.7 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.