This standard is issued under the fixed designation A 501; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript epsilon ( ュ) indicates an editorial change since the last revision or reapproval.

This specification has been approved for use by agencies of the Department of Defense. Consult the DoD Index of Specifications and Standards for specific year of issue which has been adopted by the Department of Defense.

1. Scope
1.1 This specification covers hot-formed welded and seamless carbon steel square, round, rectangular, or special shape structural tubing for welded, riveted, or bolted con-struction of bridges and buildings, and for general structural purposes.
1.2 Square and rectangular tubing is furnished in sizes 1 to 10 in. (25.4 to 254 mm) across flat sides with wall thicknesses 0.095 to 1,000 in. (2.41to 25.40 mm), depending on size; round tubing is furnished in NPS 1/2 to 24 (Note), incl, with nominal (average)wall thicknesses 0.109 to 1.000 in. (2.77 to 25.40 mm), depending on size. Tubing having other dimensions may be furnished provided such tubing complies with all other requirements of this specification.
1.3 Tubing may be furnished with hot-dipped galvanized coating.
1.4 The values stated in inch-pound units are to be regarede as the standard.
NOTE-The dimensionless designator NPS(nominal pipe size)has been substituted in this standard for shuh traditional terms as "nominal diameter,""size", and "nominal size."