1.1 本规范 涵盖最小壁厚的无缝冷拔碳钢管，包括弯曲成U形管（如果指定），用于管式给水加热器。 1.2 所涵盖的管道尺寸应为 5 / 8 到1 1 / 4 -在。[15.9至31.8毫米]外径（含），最小壁厚等于或大于0.045英寸。[1.1毫米]。 1.3 提供了可选的补充要求，如果需要，应在订单中说明。 1.4 以英寸-磅单位或国际单位制单位表示的值应单独视为标准。在正文中，国际单位制单位显示在括号中。每个系统中陈述的值并不完全等同；因此，每个系统必须独立使用。合并两个系统的值可能导致不符合规范。除非订单中指定了本规范的“M”名称，否则应适用英寸-磅单位。 1.5 一个 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》中确立的国际公认的标准化原则制定的。

1.1 This specification covers minimum-wall-thickness, seamless cold-drawn carbon steel tubes including bending into the form of U-tubes, if specified, for use in tubular feedwater heaters. 1.2 The tubing sizes covered shall be 5 / 8 to 1 1 / 4 -in. [15.9 to 31.8-mm] outside diameter, inclusive, with minimum wall thicknesses equal to or greater than 0.045 in. [1.1 mm]. 1.3 Optional supplementary requirements are provided, and when desired, shall be stated in the order. 1.4 The values stated in either inch-pound units or SI units are to be regarded separately as the 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.