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 furnished in sizes 1 to 32 in. [25 to 800 mm] across flat sides with wall thicknesses 0.095 to 3.00 in. [2.5 to 75 mm], dependent upon size; round tubing is furnished in NPS ¹/₂ [DN 15] to NPS 24 [DN 600] (see Note 1) inclusive, with nominal (average) wall thicknesses 0.109 to 1.000 in. [2.8 to 25.4 mm], dependent upon size. Special shape tubing and tubing with other dimensions is permitted to be furnished, provided that such tubing complies with all other requirements of this specification.

Note 1: The dimensionless designator NPS [DN] (nominal pipe size) has been substituted in this standard for such traditional terms as “nominal diameter,” “size,” and “nominal size.”

1.3 This specification covers the following grades:

1.3.1 Grade A — 36 000 psi [250 MPa] min yield strength.

1.3.2 Grade B — 50 000 psi [345 MPa] min yield strength.

1.4 An optional supplementary requirement is provided for Grade B and, when desired, shall be so stated on the order.

1.5 The following precautionary statement pertains only to the test method portion of this specification: This standard does not purport to address all the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

1.6 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.

1.7 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.