ASTM A501 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.

The term Hollow Structural Sections (HSS) refers to high-strength welded steel tubing used as structural elements in buildings and other structures and a variety of manufactured products. It is produced in round, square and rectangular shapes and a broad range of sizes to the ASTM A500, A501, A1085, A1065 specifications.

Sizes：

Square Tubing: OD: 1" x 1" - 32" x 32" x Thk.: 0.100" - 3.000"  (25 x 25mm - 800 x 800mm x Thickness: 2.5 - 75 mm)

Rectangular Tubing: OD: 1" x 1.5" - 22" x 32"  x Thk.: 0.100" - 3.000" (25 x 38mm - 500 x 800mm x Thickness: 2.5 - 75mm)

ASTM A501 Round Tubing is furnished in size:

OD: NPS 1/2" - NPS 24" (DN15 - DN 600 or 21.3 - 609.6mm)  x Thickness: 0.109" to 1.000". (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: 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.”

ASTM A501 covers the following grades:

Chemical Component(%)

Mechanical Properties Min (MPa)

Equivalent Grades: EN 10219-1/EN 10210-1 S355, ASTM A500 Gr.B, GB/T 3091 Q355B, JIS G3444/3466 STK/STKR490