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 or bridges and buildings, and for general structural purposes. Special shape and dimensions of tubing are permitted to be furnished provided that such tubing comply with all other requirements of this specification. Test specimens shall be in accordance with other ASTM documents enlisted herein. The tubing shall be manufactured either by seamless, furnace-butt welding (continuous welding), electric-resistance welding or submerged arc welding. Testing of the sample specimens shall include one tension test from a length of each of the tubing representing each lot. If any lot fails the mechanical test, it shall be rejected or retested using additional tubing of double the original number from the lot. The lot shall be acceptable if the results of all such retests conform to the specified requirements.

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.