1.1 本规范 2. 包括无缝铁素体和奥氏体钢锅炉、过热器和热交换器管，指定等级为T5、TP304等。这些钢列在 表1和 2. . 1.2 在名称中包含字母H的等级的要求与不包含字母H.的类似等级的要求不同。这些不同的要求提供了比没有这些不同要求的类似等级通常可实现的更高的蠕变断裂强度。 1.3 通常按照本规范提供的卡套管尺寸和厚度为 1. / 8. 内径为3.2mm至127mm，外径为0.015至0.500英寸[0.4至12.7mm，包括最小壁厚或平均壁厚（如果订单中有规定）。可提供具有其他直径的管道，前提是此类管道符合本规范的所有其他要求。 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 seamless ferritic and austenitic steel boiler, superheater, and heat-exchanger tubes, designated Grades T5, TP304, etc. These steels are listed in Tables 1 and 2 . 1.2 Grades containing the letter, H, in their designation, have requirements different from those of similar grades not containing the letter, H. These different requirements provide higher creep-rupture strength than normally achievable in similar grades without these different requirements. 1.3 The tubing sizes and thicknesses usually furnished to this specification are 1 / 8 in. [3.2 mm] in inside diameter to 5 in. [127 mm] in outside diameter and 0.015 to 0.500 in. [0.4 to 12.7 mm], inclusive, in minimum wall thickness or, if specified in the order, average wall thickness. Tubing having other diameters may be furnished, provided such tubes comply with all other requirements of this specification. 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.