1.1 本规范涵盖了用于低压管道的五个等级的焊接锻造奥氏体不锈钢配件，用于低温和中等温度以及一般腐蚀性服务。用户应注意，某些腐蚀条件可能会限制一个或多个等级的使用。对于需要热处理或全压额定值产品的应用，请参阅质量标准 A403/A403M 术语“配件”适用于对接和承插焊接部件，例如45°和90°弯头、三通、异径管、Y形管、侧向管、十字管和短端。 1.2 本规范涵盖3至48英寸的焊接接头。外径为[75至1225毫米]，标称壁厚为0.062至0.500英寸。[1.6至12.7毫米]。 表1 和 表2 列出本规范中接头的常用直径和公称厚度。1.3 本规范不适用于铸造配件。规范涵盖了铸造奥氏体钢配件 A351M . 1.4 对于需要更大程度检查的配件，提供了可选的补充要求。这些补充要求需要额外的测试。如果需要，可以按顺序指定这些中的一个或多个。 1.5 本规范以英寸-磅单位和国际单位制单位表示。但是，除非订单规定了适用的“M”规格名称（SI单位），否则材料应按英寸-磅单位提供。 1.6 以SI单位或英寸-磅单位表示的值应单独视为标准值。在正文中，国际单位制单位显示在括号中。每个系统中陈述的值可能不完全等同；因此，每个系统应独立使用。合并两个系统的值可能导致不符合标准。 1.7 本国际标准是根据世界贸易组织技术性贸易壁垒（TBT）委员会发布的《关于制定国际标准、指南和建议的原则的决定》中确立的国际公认的标准化原则制定的。

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.