1.1 本规范涵盖用于桥梁和建筑物的焊接、铆接或螺栓连接施工以及一般结构用途的黑色和热浸镀锌热成型焊接和无缝碳钢方形、圆形、矩形或特殊形状结构管。 1.2 方形和矩形管由1至16英寸的扁钢制成。[25至405 mm]和规定壁厚0.095至1.0 in。[2.5至25毫米]。圆管的直径为1到48英寸。[25至1220 mm]，规定壁厚为0.095至4.00 in。[2.5至100 mm]。 1.3 本规范涵盖三个等级:A、B和C。 1.4 本规范的文本包含提供解释材料的注释和脚注。 此类注释和脚注（不包括表和图中的注释和脚注）不包含任何强制性要求。 1.5 本规范以英寸-磅单位和国际单位制表示；但是，除非采购订单规定了适用的M规格名称（国际单位制），否则英寸-磅单位应适用。以国际单位制或英寸-磅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可能不是精确的等效值；因此，每个系统应相互独立使用。将两个系统的值合并可能会导致不符合标准。 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》中确立的国际公认标准化原则制定的。

1.1 This specification covers black and hot-dipped galvanized hot-formed welded and seamless carbon steel square, round, rectangular, or special shape structural tubing for welded, riveted, or bolted construction of bridges and buildings, and for general structural purposes. 1.2 Square and rectangular tubing is produced with flats of 1 to 16 in. [25 to 405 mm] and a specified wall thickness 0.095 to 1.0 in. [2.5 to 25 mm]. Round tubing is produced with diameters of 1 to 48 in. [25 to 1220 mm] and a specified wall thickness of 0.095 to 4.00 in. [2.5 to 100 mm]. 1.3 This specification covers three grades: A, B, and C. 1.4 The text of this specification contains notes and footnotes that provide explanatory material. Such notes and footnotes, excluding those in tables and figures, do not contain any mandatory requirements. 1.5 This specification is expressed in both inch-pound units and in SI units; however, unless the purchase order specifies the applicable M specification designation (SI units), the inch-pound units shall apply. 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 nonconformance with the standard. 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.