1. Scope

1. Scope

1.1 This specification covers laser beam or laser hybrid welded, built-up, carbon steel, sharp-cornered profiles (SCP) square, rectangular, or custom shape structural tubing for welded, riveted, or bolted construction. SCP tubing 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—There is no standard for other sharp-cornered laser or laser hybrid welded carbon steel structural shapes, but Appendix X1 provides guidance on their specification.
1.2 The SCP structural tubing sections produced to this specification have a perimeter of 2845 mm [112 in.] or less and wall thickness of between 4.76 and 38.1 mm [3/16 and 1.50 in.]. The thicknesses of walls within a specified SCP tube shape can be different.
1.3 This specification establishes the minimum requirements for manufacturing of built-up, SCP laser, and laser hybrid welded carbon steel tube sections and requires the welds to, at a minimum, match the tensile and yield strength of the base metal.
NOTE 2—Product covered by this specification is manufactured in small lots on dedicated production lines. Requiring the same lot testing that is done on large quantities of identical structural tubing products would impose an unreasonable cost burden. Product quality requirements are ensured through welding procedure qualification of the manufacturing facility in accordance with AWS, ISO, or CSA requirements. When required, Supplementary S1 tensile, S2 bend, and S3 Charpy-V notch lot testing can be specified.
NOTE 3—Because of the varying requirements of the end-use applications, four different length tolerance and weld inspection levels may be specified.
1.4 This specification uses Specifications A36/A36M, A572/A572M, EN 10025-2, or EN 10025-3 for the chemical and mechanical requirements of the designated strength grade.
1.5 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.
1.6 Units—The values stated in either SI units or inch-pound units are to be regarded separately as standard. 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.
1.7 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.
1.8 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

rectangular tube; square tube; special shape; sharp cornered; built-up; laser weld; laser-hybrid weld; fusion welding; carbon steel; AESS; SCP; architectural steel; architectural steel profiles.

Rationale

This is the second ballot. Changes were made as the result of a review by an ASTM Editor and in response to 1 persuasive negative (weight limit removal - discussed in sub) and 3 affirmatives with comment. The changes based on the comments were editorial or added clarity and added inspection requirement details from the referenced standards for the convenience of users. ASTM A606 was not added, as most are not laser weldable.

In the scope of AWS D1.1, it states, “This code contains the requirements for fabricating and erecting welded steel structures,” but it does not cover dedicated production methods for structural shapes. Architectural and industrial applications are increasingly using short runs of precision, built-up, sharp cornered profile (SCP), laser, and laser hybrid steel tube products from dedicated production lines, particularly when aluminum does not satisfy the structural requirements. SCP steel tube sections are used when the round corners of standard tubular products do not satisfy the dimensional requirements. The applications include life safety critical curtain wall, window mullion, egress stairs, and industrial applications. The abbreviation SCP is commonly used when specifying this product.

In a series of emails in 2019, Mr. Ehlert of Novum Structures, a fabricator who purchases the product, communicated the need for this ASTM standard, while mentioning that a standard already exists for laser and laser hybrid welded stainless steel (ASTM A1069/A1069M). His firm provided a letter of support, feedback on draft development, and has requested the addition of Canadian Standards Association CSA W47.1. U.S., Canadian, and European fabricators and U.S. and European manufacturers are formally requesting this standard and there have also been requests from structural engineers using this product. European and U.S. manufacturers of this product, Montanstahl, and Stainless Structurals significantly contributed to the draft. Additional fabricators who purchase SCP steel, specifically TriPyramid, Feature Walters, Haskell, Newport Industrial Fabrication, Sentech, Seele, Roschmann Group, and Mistral Architectural Metal & Glass, have written letters of support.

Currently, some are specifying carbon steel to ASTM A1069/A1069M, which is for laser and laser hybrid welded stainless steel because of the lack of a carbon steel standard, which is problematic. ANSI/AISC 360 provides the expected weld design strength but does not limit the welding methods that can be used for SCP products or establish quality requirements. Simply referencing AWS D1.1, ISO, or CSA W47.1 (Canada) is not sufficient to define the requirements for SCP tube. This standard will fill the existing specification gap.

The stainless steel standard, ASTM A1069, was used as the starting point for this draft. The ISO, CSA, and AWS standards for laser and laser hybrid operator and process qualification apply to all steels and, since users of the standard may not have these documents for reference but may want to understand their requirements, they have been summarized in Appendix X2. Referencing them avoids a conflict between standards and unnecessary standard length while capitalizing on standard-setting body expertise. While these standards set welding qualification requirements, final product dimensional tolerances, inspection, and other requirements are equally important in producing a high-quality structural shape.

Because this is a short run, customized product, some of the requirements for large production runs of carbon steel tube are not applicable such as continuous identification marking. Raw material is purchased to the chemistry requirements of other standards. Custom laser and laser hybrid carbon steel structural shapes other than tube are purchased so a nonmandatory appendix provides guidance for specifiers of these products since it has been determined that there is currently no A01 subcommittee that is an appropriate fit for a standard covering these products.

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