1.1 本规范 2. 涵盖多个等级的最小壁厚、无缝、碳钼合金钢、锅炉和过热器管。 1.2 本规范涵盖管道 1. / 2. 至5英寸。[12.7至127 mm]，包括外径和0.035至0.500 in。[0.9至12.7 mm]，包括最小壁厚。 1.3 提供了可选的补充要求，如需要，应在订单中说明。 1.4 以英寸-磅单位或国际单位表示的数值应单独视为标准值。在文本中，国际单位显示在括号中。每个系统中规定的值不是精确的等价物；因此，每个系统必须相互独立使用。合并两个系统的值可能会导致不符合规范。除非订单中规定了本规范的“M”名称，否则英寸-磅单位应适用。 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《关于制定国际标准、指南和建议的原则的决定》中确立的国际公认标准化原则制定的。

1.1 This specification 2 covers several grades of minimum-wall-thickness, seamless, carbon-molybdenum alloy-steel, boiler and superheater tubes. 1.2 This specification covers tubes 1 / 2 to 5 in. [12.7 to 127 mm] inclusive, in outside diameter and 0.035 to 0.500 in. [0.9 to 12.7 mm], inclusive, in minimum wall thickness. 1.3 An optional supplementary requirement is provided and, when desired, shall be so stated in the order. 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 are not exact equivalents; therefore, each system must be used independently of the other. Combining values from the two systems may result in nonconformance with the specification. 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.