1.1 本规范 2. 覆盖厚壁碳和合金钢管( 注1 )由车削和钻孔锻件制成，适用于高温环境。根据本规范订购的管道应适用于弯曲和其他成型操作以及熔焊。选择将取决于设计、使用条件、机械性能和高温特性。 注1: 在本规范的几个章节中，“管道”一词的使用是广义的，旨在指集管或引线。 注2: 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 1.2 涵盖了几个等级的铁素体钢。它们的组成见 表1 . 1.3 提供了可选性质的补充要求（S1至S7）。 补充要求S1至S5要求进行额外的测试，必要时应在订单中说明，以及所需的此类测试数量（如适用）。 1.4 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。英寸磅单位应适用，除非订单中规定了本规范的“M”名称。 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 heavy-wall carbon and alloy steel pipe ( Note 1 ) made from turned and bored forgings and is intended for high-temperature service. Pipe ordered under this specification shall be suitable for bending and other forming operations and for fusion welding. Selection will depend on design, service conditions, mechanical properties and high-temperature characteristics. Note 1: The use of the word “pipe” throughout the several sections of this specification is used in the broad sense and intended to mean pipe headers, or leads. Note 2: The dimensionless designator NPS (nominal pipe size) has been substituted in this standard for such traditional terms as “nominal diameter,” “size,” and “nominal size.” 1.2 Several grades of ferritic steels are covered. Their compositions are given in Table 1 . 1.3 Supplementary requirements (S1 to S7) of an optional nature are provided. Supplementary requirements S1 to S5 call for additional tests to be made, and when desired shall be so stated in the order, together with the number of such tests required as applicable. 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. The inch-pound units shall apply unless the “M” designation of this specification is specified in the order. 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.