ASTM A500 is a standard specification published by the ASTM for cold-formed welded and seamless carbon steel structural tubing in round, square, and rectangular shapes. It is commonly specified in the USA for hollow structural section

Hollow structural section

A hollow structural section is a type of metal profile with a hollow tubular cross section. In some countries they are referred to instead as a structural hollow section ....

s, but the more stringent CSA G40.21 is preferred in Canada. Another related standard is ASTM A501, which is a hot-formed version of this A500. ASTM A500 defines four grades of carbon steel based primarily on material strength.

This is a standard set by the standards organization ASTM International

ASTM International

ASTM International, known until 2001 as the American Society for Testing and Materials , is an international standards organization that develops and publishes voluntary consensus technical standards for a wide range of materials, products, systems, and services...

, a voluntary standards development organizations that sets technical standards for materials, products, systems, and services.

Density

Like other carbon steels, A500 and A501 steels have a specific gravity of approximately 7.85, and therefore a density of approximately 7850 kg/m³ (0.284 pounds per cubic inch).

Grades

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 Unified numbering system The unified numbering system is an alloy designation system widely accepted in North America. It consists of a prefix letter and five digits designating a material composition. A prefix of S indicates stainless steel alloys, C for copper, brass, or bronze alloys, T for tool steels, etc...	| Composition (% by weight in heat)					| Minimum strength requirements
		C Carbon Carbon is the chemical element with symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds...	Mn Manganese Manganese is a chemical element, designated by the symbol Mn. It has the atomic number 25. It is found as a free element in nature , and in many minerals...	P Phosphorus Phosphorus is the chemical element that has the symbol P and atomic number 15. A multivalent nonmetal of the nitrogen group, phosphorus as a mineral is almost always present in its maximally oxidized state, as inorganic phosphate rocks...	S Sulfur Sulfur or sulphur is the chemical element with atomic number 16. In the periodic table it is represented by the symbol S. It is an abundant, multivalent non-metal. Under normal conditions, sulfur atoms form cyclic octatomic molecules with chemical formula S8. Elemental sulfur is a bright yellow...	Cu Copper Copper is a chemical element with the symbol Cu and atomic number 29. It is a ductile metal with very high thermal and electrical conductivity. Pure copper is soft and malleable; an exposed surface has a reddish-orange tarnish...	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