clause5.io/ welding/ aws-d1-1

What D1.1 Governs

AWS D1.1/D1.1M:2025 governs welding of structural steel components in buildings, industrial structures, and other non-bridge, non-pipe applications. The 2025 edition covers 5 welding processes (SMAW, SAW, GMAW, FCAW, and GTAW) across more than 100 base metals listed in Table 5.6, on carbon and low-alloy steels with minimum yield strengths up to 100 ksi (690 MPa). The 2025 edition is the 25th, superseding the 2020 (24th) edition.

AWS D1.1 is the primary welding code for structural steel in the United States, governing an estimated 70% of structural steel welding nationally. Clause 1.1 defines its scope: the requirements for fabricating and erecting welded steel structures. When D1.1 is stipulated in contract documents, conformance with all provisions is required except where the Engineer specifically modifies or exempts them per Clause 1.5.1.

The code applies to carbon and low-alloy steels that are 1/8 in [3 mm] or thicker with a minimum specified yield strength of 100 ksi [690 MPa] or less. This covers the vast majority of structural steel used in buildings, bridges, and industrial structures.

Common steels include A36, A572 Gr.50, A992, A588 weathering steel, and A913 high-strength grades. Verify your steel against Table 5.6 using your mill test report.

D1.1 covers both nontubular members (wide-flange beams, plates, angles, channels) and tubular structures (hollow structural sections, pipe columns used as structural members). Clause 10 provides additional requirements specific to tubular connections.

What D1.1 Does Not Cover

Clause 1.4 explicitly directs users to other AWS codes for applications outside its scope. Aluminum welding falls under D1.2. Sheet steel under 1/8 in thick is covered by D1.3.

Reinforcing steel uses D1.4. Stainless steel is governed by D1.6. Highway bridge welding has its own code in AASHTO/AWS D1.5. Strengthening and repair of existing structures is addressed in D1.7 and D1.8. Titanium falls under D1.9.

Pressure vessels, boilers, and piping systems are entirely outside D1.1 scope. These are governed by the ASME Boiler and Pressure Vessel Code. Cross-country pipelines are governed by API 1104. The distinction is critical: a structural pipe column in a building uses D1.1, but a pressurized steam pipe in the same building uses ASME.

The 11 Clauses of D1.1:2025

D1.1 is organized into 11 clauses: General Requirements (1), Normative References (2), Terms (3), Design (4), Prequalification (5), Qualification (6), Fabrication (7), Inspection (8), Stud Welding (9), Tubular (10), and Strengthening/Repair (11). Clauses 5 and 6 govern WPS paths. Clause 8 governs inspector acceptance criteria.

D1.1:2025 is organized into 11 clauses that cover the full lifecycle of a welded steel structure, from design through inspection. Unlike ASME IX, which addresses only qualification, D1.1 is a single comprehensive document covering design, procedure development, fabrication, and quality control.

Clause 1 — General Requirements

Scope, limitations, responsibilities of the Engineer, Contractor, and Inspector. Defines what the code covers (structural steel) and what it excludes. Establishes the authority hierarchy for contract documents.

Clause 2 — Normative References

Lists all reference documents required for implementation, including AWS, ASTM, and ANSI standards that D1.1 incorporates by reference.

Clause 3 — Terms and Definitions

Definitions for terms used throughout the code. Critical for interpreting requirements consistently, particularly distinctions like discontinuity versus defect, and prequalified versus qualified.

Clause 4 — Design of Welded Connections

Requirements for designing welded connections in nontubular and tubular members. Covers effective weld areas, allowable stresses, fatigue design, and joint configuration details for both statically and cyclically loaded structures.

Clause 5 — Prequalification of WPSs

The prequalified path. Welding Procedure Specifications that meet all requirements of Clause 5 are exempt from the qualification testing required in Clause 6. Covers approved base metals (Table 5.6), filler metal matching (Table 5.7), preheat requirements (Table 5.11), prequalified joint details (Figure 5.1), and essential variables (Table 5.5).

Clause 6 — Qualification

WPS qualification by testing and welding personnel performance qualification. When a procedure does not meet all prequalified requirements of Clause 5, it must be qualified by testing per Clause 6. Table 6.6 lists 35 essential variables for procedure qualification. Also covers welder and welding operator performance tests.

Clause 7 — Fabrication

Requirements for production welding, including base metal preparation, preheat and interpass temperatures (Clause 7.6), heat input control for quenched and tempered steels (Clause 7.7), minimum fillet weld sizes (Table 7.7), weld profiles, repairs, and dimensional tolerances.

Clause 8 — Inspection

Inspector qualifications, acceptance criteria for visual inspection (Table 8.1), and procedures for nondestructive testing including magnetic particle testing, radiographic testing, and ultrasonic testing. Clause 8.9 provides the visual inspection acceptance criteria that inspectors apply daily.

Clause 9 — Stud Welding

Requirements for welding studs to structural steel, including stud base qualification, technique, and inspection criteria. Covers headed studs used as shear connectors in composite construction.

Clause 10 — Tubular Structures

Requirements specific to tubular connections, including joint design, WPS qualification for tubular joints, and inspection of tubular welds. All other clauses also apply to tubulars unless specifically noted otherwise.

Clause 11 — Strengthening and Repair of Existing Structures

Requirements for welded modification or repair of existing steel structures. Addresses the unique challenges of welding on structures that may be under load, including heat effects on existing members and fatigue life considerations.

Prequalified vs. Qualified WPS

D1.1 Clause 5 allows prequalified WPSs for common joints and processes without testing — the fabricator documents compliance with Table 5.1, 5.3, 5.4, and Figure 5.1. Clause 6 requires qualification by testing (PQR) for any WPS that falls outside prequalified limits. Most structural steel fabrication uses prequalified WPSs.

D1.1 provides two distinct paths to a compliant Welding Procedure Specification, and the distinction is one of the most important concepts in the code.

The Prequalified Path (Clause 5)

Clause 5 defines prequalified WPSs — procedures that the code has already validated through decades of industry experience. Prequalification of WPSs shall be defined as exempt from the WPS qualification testing required in Clause 6.

To be prequalified, a WPS must conform with all applicable requirements of Clause 5: approved welding process (SMAW, SAW, GMAW except short-circuit, or FCAW), base metal listed in Table 5.6, filler metal per Table 5.7, joint detail from Figure 5.1, and preheat per Table 5.11.

This path eliminates the cost and time of qualification testing. Many structural fabrication shops work exclusively with prequalified joints and never need a Procedure Qualification Record (PQR). A typical building frame using A992 steel with E71T-1 FCAW wire and standard CJP groove welds or fillet welds qualifies entirely under Clause 5.

The Non-Prequalified Path (Clause 6)

When any element of a procedure falls outside the prequalified limits of Clause 5, the WPS must be qualified by testing per Clause 6. This requires producing a test weld, extracting specimens, performing destructive tests, and documenting the results on a PQR. Common triggers include using GMAW short-circuit transfer, welding joint geometries not in Figure 5.1, or working with base metals not listed in Table 5.6.

D1.1’s prequalified path has no equivalent in ASME IX. Under Section IX, every WPS requires procedure qualification — there is no prequalified exemption. This is one of the most significant structural differences between the two codes. For ASME IX or API 1104, separate requirements apply.

After fabrication, Clause 8 governs inspection. Table 8.1 defines visual acceptance criteria for eight discontinuity categories — from cracks (zero tolerance) to porosity (measurable limits). See the weld defects overview for the complete Table 8.1 breakdown. Before welding begins, the mill test report (MTR) confirms the base metal meets Table 5.6 group requirements and feeds the preheat lookup.

D1.1:2025 Compliance Tools

Clause5 provides free D1.1 compliance calculators: preheat temperature lookup (Table 5.11), heat input calculation, carbon equivalent (Annex B), minimum fillet weld size (Table 7.7), and deposition rate. Each calculator returns the exact code reference and applicable clause.

Each tool below applies a specific D1.1:2025 requirement. Select a calculator to look up the value for your application.

How D1.1 Compares to Other Welding Codes

D1.1 is one of several welding codes engineers encounter. The primary differences are scope, preheat methodology, base metal grouping, and whether prequalified WPSs are available. D1.1 covers structural steel; ASME IX covers pressure equipment; D1.5 covers highway bridges; CSA W59 covers Canadian structural steel.