1.1This specification covers grades of hot-formed welded and seamless high-strength low-alloy square, rectangular, round, or special shape structural tubing for welded, riveted, or bolted construction of bridges and buildings and for general structural purposes. When the steel is used in welded construction, the welding procedure shall be suitable for the steel and the intended service.

1.2Square and rectangular tubing is produced with flats of 1 in. to 16 in. [25 mm to 405 mm] and a specified wall thickness of 0.095 in. to 1.0 in. [2.5 mm to 25 mm]. Round tubing is produced with diameters of 1 in. to 48 in. [25 mm to 1220 mm] and a specified wall thickness of 0.095 in. to 2.50 in. [2.5 mm to 65 mm].

1.3This specification covers the following grades: Ia, Ib, II, III, IV, V, VI and VII.

1.4The 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.

1.5This 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.

1.6This 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.