This specification covers cold-formed welded and seamless carbon steel round, square, rectangular, or special shape structural tubing for welded, riveted, or bolted construction of bridges and buildings, and for general structural purposes. This tubing shall be produced in both welded and seamless sizes and must have the chemical requirements of carbon, manganese, phosphorus, sulfur, and copper. The steel shall be produced by either open-hearth, basic-oxygen, or electric-furnace melting process. When steels of different grades are sequentially strand cast, the steel producer shall identify the resultant transition material and remove it using an established procedure that positively separates the grades. The tubing shall then be made by a seamless or welding process. Welded tubing shall be made from flat-rolled steel by the electric-resistance-welding process. The longitudinal butt joint of welded tubing shall be welded across its thickness in such a manner that the structural design strength of the tubing section is assured. Tension test and flattening test shall be conducted to the specimens. All tubing shall be inspected at the place of manufacture to ensure conformance to the requirements of this specification and must have a workmanlike finish that is free from defects.
A500 cold-formed tubing comes in four grades based on chemical composition, tensile strength, and heat treatment. The yield strength requirements are higher for square and rectangular than for round tubing. The minimum copper content is optional. Grade D must be heat treated.
|Grade||UNS||Composition (% by weight in heat)||Minimum strength requirements|
|C||Mn||P||S||Cu||tensile||yield (round)||yield (shaped)||elongation|
|max %||max %||max %||max %||min %||MPa (ksi)||MPa (ksi)||MPa (ksi)||%|
|A||K03000||0.26||1.35||0.035||0.035||0.20||310 (45)||230 (33)||270 (39)||25|
|B||K03000||0.26||1.35||0.035||0.035||0.20||400 (58)||290 (42)||315 (46)||23|
|C||K02705||0.23||1.35||0.035||0.035||0.20||425 (62)||315 (46)||345 (50)||21|
|D||K03000||0.26||1.35||0.035||0.035||0.20||400 (58)||250 (36)||250 (36)||23|