1.1 本规范 2. 包括用于高温环境的无缝奥氏体钢管。所涵盖的等级包括专门用于高温环境的H等级和氮等级。 注1: 本规范最初用于发电热电厂中心站的管道。然而，其用途不限于此类应用，也可用于本规范规定的材料属性适用的其他应用。 1.2 提供了可选的补充要求（S1至S10）。这些补充要求规定了只有在订单中规定的情况下才能进行的额外测试，以及所需的此类测试数量。 1.3 TP321和TP321H级对公称壁厚大于 3. / 8. 英寸[9.5毫米]。 1.4 以英寸磅单位或国际单位制表示的数值应单独视为标准值。 在文本中，SI单位显示在括号中。每个系统中规定的值可能不完全相等；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。除非订单中规定了本规范的“M”名称，否则应采用英寸磅单位。 注2: 在本标准中，无量纲指示符NPS（公称管道尺寸）和DN（公称直径）已被替换为“公称直径”、“尺寸”和“公称尺寸”等传统术语 1.5 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《国际标准、指南和建议制定原则决定》中确立的国际公认标准化原则制定的。

1.1 This specification 2 covers seamless austenitic steel pipe intended for high-temperature service. Among the grades covered are H grades and nitrogen grades that are specifically intended for high-temperature service. Note 1: This specification was originally developed for use for piping in the central stations of electric-power generating thermal plants. However, its use is not restricted to such applications and it may be used in other applications for which the attributes of the materials, as defined by this specification, are appropriate. 1.2 Optional supplementary requirements (S1 through S10) are provided. These supplementary requirements specify additional tests that will be made only when stated in the order, together with the number of such tests required. 1.3 Grades TP321 and TP321H have lower strength requirements for nominal wall thicknesses greater than 3 / 8 in. [9.5 mm]. 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 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. The inch-pound units shall apply unless the “M” designation of this specification is specified in the order. Note 2: The dimensionless designators NPS (nominal pipe size) and DN (Diametre Nominel) have 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.