1.1 本规范涵盖了几种等级的碳钢和合金钢无缝机械管。等级列于 表1- 3 当焊接用于连接可焊接机械管等级时，焊接程序应适合等级、部件状况和预期服务。 1.2 本规范涵盖尺寸为12（含12）的无缝热精整机械管和无缝冷精整机械管 3 / 4 在。[325 mm]外径，适用于具有所需壁厚的圆管。 1.3 根据买方的规定，管道应具有以下形状:圆形、方形、矩形和特殊截面。 1.4 提供了可选性质的补充要求，如果需要，应在订单中注明。1.5 以SI单位或英寸-磅单位表示的值应单独视为标准。在正文中，SI单位显示在括号或圆括号中。每个系统中陈述的值可能不完全等同；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。除非订单中指定了本规范的“M”名称，否则应适用英寸-磅单位。在本说明书中，硬转换或合理化转换适用于直径、长度和拉伸性能。软转换适用于其他SI测量。 1.6 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 several grades of carbon and alloy steel seamless mechanical tubing. The grades are listed in Tables 1- 3 . When welding is used for joining the weldable mechanical tube grades, the welding procedure shall be suitable for the grade, the condition of the components, and the intended service. 1.2 This specification covers both seamless hot-finished mechanical tubing and seamless cold-finished mechanical tubing in sizes up to and including 12 3 / 4 in. [325 mm] outside diameter for round tubes with wall thicknesses as required. 1.3 The tubes shall be furnished in the following shapes, as specified by the purchaser: round, square, rectangular, and special sections. 1.4 Supplementary requirements of an optional nature are provided and when desired shall be so stated in the order. 1.5 The values stated in either SI units or inch-pound units are to be regarded separately as the standard. Within the text, the SI units are shown in brackets or parentheses. 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. In this specification hard or rationalized conversions apply to diameter, lengths and tensile properties. Soft conversion applies to other SI measurements. 1.6 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.