1.1 本规范 2. 涵盖了压力系统中用于环境和高温服务的锻造碳钢管道组件。包括按照买方规定的尺寸或按照第节中引用的MSS、ASME和API规范等尺寸标准订购的法兰、配件、阀门和类似零件 2. .根据本规范制造的锻件最大重量限制为10 000磅[4540公斤]。可根据规范要求订购更大的锻件 266/A266M .压力容器壳体用管板和空心圆柱形锻件不包括在本规范的范围内。尽管本规范涵盖了一些由轧制棒材和无缝管材加工而成的管道部件（参见 5.2 )，不包括以这些产品形式生产的原材料。 1.2 当需要额外的测试或检查时，提供了补充要求。只有当买方在订单中单独规定时，这些规定才适用。 1.3 规格 266/A266M 包括其他钢锻件和规范 A675/A675米 和 a96 覆盖其他钢筋。 1.4 本规范以英寸磅单位和国际单位制表示。但是，除非订单规定了适用的“M”规格名称（SI单位），否则材料应以英寸-磅单位提供。以国际单位制或英寸磅单位表示的数值应单独视为标准。在正文中，国际单位制显示在括号中。每个系统中规定的值可能不是完全相等的；因此，每个系统应独立使用。 将两个系统的值合并可能导致不符合标准。 注1: 无量纲指示符NPS（公称管道尺寸）在本标准中已被“公称直径”、“尺寸”和“公称尺寸”等传统术语所取代 1.5 本国际标准是根据世界贸易组织技术性贸易壁垒委员会发布的《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 2 covers forged carbon steel piping components for ambient- and higher-temperature service in pressure systems. Included are flanges, fittings, valves, and similar parts ordered either to dimensions specified by the purchaser or to dimensional standards such as the MSS, ASME, and API specifications referenced in Section 2 . Forgings made to this specification are limited to a maximum weight of 10 000 lb [4540 kg]. Larger forgings may be ordered to Specification A266/A266M . Tubesheets and hollow cylindrical forgings for pressure vessel shells are not included within the scope of this specification. Although this specification covers some piping components machined from rolled bar and seamless tubular products (see 5.2 ), it does not cover raw material produced in these product forms. 1.2 Supplementary requirements are provided for use when additional testing or inspection is desired. These shall apply only when specified individually by the purchaser in the order. 1.3 Specification A266/A266M covers other steel forgings and Specifications A675/A675M and A696 cover other steel bars. 1.4 This specification is expressed in both inch-pound units and SI units. However, unless the order specifies the applicable “M” specification designation (SI units), the material shall be furnished to inch-pound units. 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. Note 1: The dimensionless designator NPS (nominal pipe size) has been substituted in this standard for such traditional terms as “nominal diameter,” “size,” and “nominal size.” 1.5 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.