1. Scope

1. Scope
1.1 This specification covers laser or laser-hybrid welded stainless steel square, rectangular, or custom shape structural tubing for welded, riveted, or bolted construction. This tube has either a sharp-cornered profile (SCP) or is built-up tube with rounded corners. This product is used in, but not limited to, the following applications: buildings and structures, including architecturally exposed steel structures (AESS); architectural steel profiles such as curtain wall, staircases, and others; industrial; and general structural applications.
NOTE 1—The term laser fusion is also used to describe laser welding.
1.2 This tubing is manufactured from multiple pieces of plate, bar, sheet, strip, or shapes, potentially in different thicknesses by laser or laser-hybrid welding in accordance with the requirements of A1069/A1069M. It is available in sizes up to 36 in. (914 mm) outside dimension, and the wall thickness shall be +/- 5 % of the specified wall thickness. Corner welds are permissible.
1.3 This specification establishes the minimum requirements for manufacturing of laser and laser hybrid welded stainless steel tube and requires the welds to, at a minimum, match the tensile and yield strength of the base metal. If base metals of different strengths are used, the lower strength base metal shall be matched.
1.4 This specification refers to Specifications A240/A240M, A276/A276M or A479/A479M for chemical requirements, but the mechanical test requirements are determined by the mechanical properties section of this standard. This standard includes four strength grades. The default strength grade 1 is determined by the base metal standard. Grades 2 through 4 are for specification of higher strength levels.
1.5 Supplementary requirements (S1 Charpy V- notch, S2 Corrosion, S3 Tensile, and S4 Bend) of an optional nature are provided. They shall apply only when specified by the purchaser.
NOTE 2—Because of the varying requirements of the end-use applications, different length tolerance, weld inspection levels, strength levels and other requirements may be specified.
NOTE 3—Product covered by this specification is manufactured in small lots on dedicated production lines. Product quality requirements are ensured through welding procedure qualification of the manufacturing facility in accordance with A1069/A1069M. The country of origin and base metal heat numbers are identified by wall thickness on the product certificate of compliance.
1.6 The text of this specification contains notes and footnotes that provide explanatory material. Such notes and footnotes, excluding those in tables and figures, do not contain any mandatory requirements.
1.7 Units—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 inch-pound units or SI 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.
1.8 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 and health practices and determine the applicability of regulatory limitations prior to use.
1.9 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.

Keywords

tube; structural; sharp-cornered profile (SCP); built-up tube; laser fusion; laser welding; laser-hybrid welding; architecturally exposed steel structures (AESS); industrial tube; square tube; stainless steel; rectangular tube; special shape tube

Rationale

This ballot is in response to an emergency situation. It needs to pass prior to October 2023, so that can be approved for inclusion in the revision of AISC 370, that will begin balloting in February 2024. While ASTM A1069/A1069M covers laser or laser-hybrid welded stainless steel open structural sections and ASTM A1123/A1123M covers carbon steel laser or laser-hybrid welded tube, there is no standard for stainless steel laser or laser-hybrid welded square, rectangular, or custom shape structural tubing.
Initially, this tube was going to be included in a revision to A554, but there were objections. That made a new standard specifically for this product necessary. There is an existing market for this tube, but, without a separate specification, specifiers have to reference the requirements of A1069/A1069M.
This specialized tube is manufactured from multiple pieces of plate, bar, sheet, strip, or shapes, potentially in different thicknesses and has either a sharp-cornered profile (SCP) or is built-up tube with deliberately rounded corners, often for safety.
Unlike other structural stainless steel tube, this is a small run, high precision product with a wall thickness tolerance that is +/- 5 % of the specified wall thickness and corner welds are permissible since laser and laser-hybrid welds are stronger than the base metal. It is used in, but not limited to, the following applications: buildings and structures, including architecturally exposed steel structures (AESS); architectural steel profiles such as curtain wall, staircases, and others; industrial; and general structural applications.

The title and scope are in draft form and are under development within this ASTM Committee.