AWS D1.1 is the Structural Welding Code for Steel, published by the American Welding Society. It sets the minimum mandatory requirements for welding any type of structure made from carbon and low-alloy constructional steels, covering everything from connection design and welder qualifications to inspection and repair. If you work in structural steel fabrication, engineering, or welding, this is the code that governs how welded joints must be designed, executed, and verified.
What the Code Covers
AWS D1.1 applies to welded structures built from the carbon and low-alloy steels commonly used in buildings, industrial facilities, and other non-bridge structural applications. Think steel-framed office buildings, warehouse structures, platforms, and heavy equipment supports. The code spans 11 clauses that collectively regulate how steel gets welded in construction, from the design stage through final inspection.
The code does not cover every type of steel or every thickness. Thin sheet steel (3/16 inch or less) falls under a separate code, AWS D1.3, which addresses cold-formed members, galvanized steel, and hollow structural sections with walls thinner than 1/8 inch. Bridge structures have their own code as well (AWS D1.5), with stricter requirements suited to the fatigue and load demands of highway and railway bridges. If your project involves standard structural steel at typical construction thicknesses, D1.1 is almost certainly the applicable code.
How the Code Is Organized
The 11 clauses move logically from general principles through design, qualification, fabrication, and inspection. Here is what each major section addresses:
- Clause 1, General Requirements: Defines the scope and limitations of the code, key definitions, and the responsibilities of each party involved in steel fabrication.
- Clause 2, Design of Welded Connections: Covers design requirements for welded connections in both tubular and nontubular members, including allowable stresses and joint configurations.
- Clause 3, Prequalification of WPSs: Spells out which Welding Procedure Specifications can skip formal qualification testing because they use well-established joint designs, processes, and base metals.
- Clause 4, Qualification: Details how to qualify a WPS through testing, plus the performance qualification tests required for welders, welding operators, and tack welders.
- Clause 5, Fabrication: Covers the practical side of getting steel welded correctly: base metal preparation, welding consumables, technique, workmanship standards, and weld repair procedures.
- Clause 6, Inspection: Sets inspector qualifications, acceptance criteria for production welds, and procedures for visual inspection and nondestructive testing (NDT) methods like ultrasonic or radiographic examination.
- Clause 7, Stud Welding: Requirements specific to welding studs (such as shear connectors) onto structural steel.
- Clause 8, Strengthening and Repairing Existing Structures: Guidance for welded modifications or repairs to structures already in service.
Clauses 3 and 4 work together in an important way. Prequalification (Clause 3) lets fabricators use certain combinations of joint type, welding process, and base metal without running a full procedure qualification test, saving significant time and cost. If a WPS falls outside those prequalified parameters, Clause 4 requires formal testing to prove the procedure produces sound welds.
Welder Qualification Requirements
AWS D1.1 requires every welder, welding operator, and tack welder to be qualified by test before they work on a governed structure. The qualification process works like this: a welder demonstrates proficiency in a specific welding process (such as shielded metal arc welding, gas metal arc welding, flux-cored arc welding, or gas tungsten arc welding) and in specific positions (flat, horizontal, vertical, overhead). Passing the test qualifies you only for the process and positions you actually demonstrated.
There is a distinction between “qualified” and “certified.” A welder becomes qualified by passing an employer-coordinated test. Certification, on the other hand, requires demonstrating proficiency at an AWS-accredited testing facility. Either way, the employer bears responsibility for verifying that each welder on the job is properly qualified and maintains continuity. If a welder goes six months or more without using a qualified process, they must requalify before resuming work under that process.
Qualifications last indefinitely as long as the welder keeps using the process. This is a meaningful benefit: once you pass, you do not need to retest on a schedule, only if you have a gap in practice.
Welding Procedure Specifications
A Welding Procedure Specification, or WPS, is a written document that spells out exactly how a particular weld joint should be made. It covers the welding process, base metal type, filler metal, preheat temperature, electrical parameters, joint design, and technique. The WPS exists so that every welder performing a given joint follows the same tested method, producing consistent results.
Under D1.1, a WPS can either be prequalified (using combinations the code has already validated through decades of use) or qualified through a Procedure Qualification Record (PQR), which documents the results of actual test welds. Prequalified WPSs save fabricators the expense of testing, but they must strictly follow the code’s parameters for joint geometry, welding process, and base metal. Deviating from any prequalified variable triggers the need for full qualification testing.
What Changed in the 2025 Edition
The most recent edition, D1.1/D1.1M:2025, introduced several changes centered on high-strength steel. The most notable is the addition of ASTM A913 Grade 80 as a prequalified base metal. A913 Gr80 is a quenched and self-tempered structural steel with an 80 ksi minimum yield strength, used in heavy column applications where designers want to reduce member sizes.
Adding this steel required a new base metal category (Group V) and a new preheat category (Category G). The preheat temperatures for A913 Gr80 match those already used for common structural steels like A992 and A572 Grade 50, but the code limits prequalified welding of Gr80 to electrodes with very low diffusible hydrogen content (H4 designation, meaning 4 mL per 100 g or less). Low-hydrogen electrodes reduce the risk of hydrogen-induced cracking, which becomes more critical as steel strength increases.
The 2025 edition also updated requirements for two other A913 grades. A913 Gr65 moved to a lower preheat category, allowing welding at reduced temperatures in more situations. A913 Gr70 received a new preheat category that permits welding with no preheat at all for sections up to 2½ inches thick, and only 150°F preheat above that thickness.
Who Uses AWS D1.1
The code is referenced by building codes, including the International Building Code, making it a legal requirement for most structural steel construction in the United States. Engineers specify it on structural drawings, fabricators follow it in the shop, erectors apply it in the field, and inspectors use it to accept or reject welds. If a set of structural steel plans says “all welding per AWS D1.1,” every weld on that project must comply with the code’s requirements for procedure qualification, welder qualification, workmanship, and inspection.
Contractors, fabrication shops, and inspection firms typically keep the current edition on hand. Because the code is updated periodically, project specifications usually reference a specific edition year. Confirming which edition applies to your project matters, since prequalified joint details, acceptance criteria, and base metal groupings can change between editions.