1.1 This specification covers three Types and two Grades of cold formed electric-fusion (arc) welded high-strength low-alloy steel tubing of 50 ksi [345 MPa] minimum yield point for use in welded or bolted construction of buildings and for general structural purposes.

1.2 This tubing is produced in square and rectangular sizes with a periphery of 200 in. [500 cm] or less and a specified wall thickness of 1.00 in. [25 mm] or less. Tubes are joined by two longitudinal electric-fusion (arc) welds. Circumferential welds are disallowed. Sizes outside of those listed in Tables 4 and 5 may be ordered provided all other requirements of the specification are met. Typical lengths are 15 to 50 ft [5 to 15 m].

NOTE 1: Products manufactured to this specification may not be suitable for those applications such as dynamically loaded elements in welded structures, etc. where low-temperature toughness properties may be important. (See Supplementary Requirement S1.)

1.3 This specification covers the following Types:

1.3.1 Type 1—Welded with backing, backing left in the product,

1.3.2 Type 2—Welded with backing, backing removed,

1.3.3 Type 3—Welded without backing.

1.4 Tubing is available in Grades 50 [345] and 50W [345W]. Grade 50 [345] is manufactured from high-strength low-alloy steel. Grade 50W [345W] is manufactured from high-strength low-alloy steel with enhanced atmospheric corrosion resistance. (See 10.1.2) The Grades may not be interchanged without approval of the purchaser. ASTM Specifications for plate that may be applied to Grade 50 [345] and 50W [345W] are listed in Reference Documents and in Table 1.

1.5 This specification is expressed in both inch-pound units and in SI units; however, unless the purchase order or contract 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.

1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.

1.7 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

ASTM Standards

A6/A6M Specification for General Requirements for Rolled Structural Steel Bars, Plates, Shapes, and Sheet Piling
A242/A242M Specification for High-Strength Low-Alloy Structural Steel
A572/A572M Specification for High-Strength Low-Alloy Columbium-Vanadium Structural Steel
A588/A588M Specification for High-Strength Low-Alloy Structural Steel, up to 50 ksi [345 MPa] Minimum Yield Point, with Atmospheric Corrosion Resistance
A656/A656M Specification for Hot-Rolled Structural Steel, High-Strength Low-Alloy Plate with Improved Formability
A700 Guide for Packaging, Marking, and Loading Methods for Steel Products for Shipment
A709/A709M Specification for Structural Steel for Bridges
A941 Terminology Relating to Steel, Stainless Steel, Related Alloys, and Ferroalloys
A945/A945M Specification for High-Strength Low-Alloy Structural Steel Plate with Low Carbon and Restricted Sulfur for Improved Weldability, Formability, and Toughness
G101 Guide for Estimating the Atmospheric Corrosion Resistance of Low-Alloy Steels

Military Standard

MIL-STD-129 Marking for Shipment and Storage

AWS Standard

AWS D1.1 Structural Welding Code-Steel

Steel Tube Institute

Hollow Structural Sections

Federal Standard

Fed. Std. No. 123 Marking for Shipment