Welding Code Standards Directory
Every major structural welding code in one place. AWS D1.1 through D1.9, ASME Section IX, API 1104, and CSA W59 — each with a free guide covering scope, key requirements, and preheat rules. Find the standard that governs your project, then use our calculators for specific requirements.
AWS D1.x — Structural Welding Codes
The AWS D1.x series covers structural welding for specific materials and applications. D1.1 governs carbon steel, D1.2 aluminum, D1.3 sheet steel, D1.4 reinforcing steel, D1.5 bridges, D1.6 stainless steel, D1.8 seismic supplement, and D1.9 titanium. Each code shares the same clause framework with material-specific requirements.
The AWS D1 family covers structural welding across different materials and applications. D1.1 is the base code for structural steel. Each subsidiary code (D1.2 through D1.9) addresses a specific material or application that requires different welding rules than general structural steel.
The primary structural welding code for steel. Covers carbon and low-alloy steels thicker than 3/16 inch. Preheat requirements in Table 5.11 based on steel category, thickness, and hydrogen level. Prequalified WPS under Clause 5. The most widely referenced welding code in the world.
Structural welding of aluminum alloys. Maximum preheat and interpass temperature of 250°F (120°C) for heat-treatable alloys. Holding time shall not exceed 15 minutes. Addresses hot cracking susceptibility rather than hydrogen cracking. SMAW is not permitted.
Structural welding of sheet steel and cold-formed members with thickness of 3/16 inch (5 mm) or less. Five arc processes: GMAW, FCAW, SMAW, GTAW, SAW. Explicitly permits GMAW short-circuit transfer (excluded from D1.1 prequalification). Prequalified WPS under Clause 5. Sheet-to-structural connections governed by normative Annex A.
Welding of reinforcing steel (rebar). Preheat based on carbon equivalent and bar size per Table 7.2. Two CE formulas (Clause 1.5.4 Eq. 1 and Eq. 2). Fillet welds are prequalified per Clause 8.1.2.1 (except GTAW). When welding rebar to structural steel, use the higher preheat of D1.4 and D1.1.
Welding of highway bridge structures. Separate preheat tables for non-fracture-critical (Tables 6.3/6.4) and fracture-critical (Tables 12.4–12.8) members. FC requirements include hydrogen level and heat input as additional variables. Covers HPS steels (HPS345W through HPS690W).
Structural welding of stainless steel. Minimum preheat is to remove moisture. Maximum interpass temperature of 350°F (175°C) for austenitic grades. Clause 5 scope is austenitic stainless only (per Clause 1.4.7). Different metallurgical concerns than carbon steel — sensitization and ferrite control rather than hydrogen cracking.
Supplements D1.1 for seismic applications. Adds demand-critical weld designations, CVN toughness requirements (two-tier: 20 ft-lbf baseline + 40 ft-lbf cold-service), maximum interpass temperature of 550°F, and restricted welding procedures. Uses D1.1 preheat tables. Current edition: 2021 (4th Edition).
Structural welding of titanium. Minimum preheat 60°F nor below ambient temperature. No preheat table — thermal control focuses on contamination prevention (O2/N2) rather than hydrogen cracking. Shielding gas per AWS A5.32. Explicitly excludes aerospace structures from scope.
ASME Section IX — Qualification Standards
ASME Boiler and Pressure Vessel Code Section IX governs welding qualification for pressure equipment. It uses P-numbers for base metals and F-numbers for filler metals. Unlike D1.1, ASME IX has no prequalified WPS path — every procedure requires qualification by testing with a PQR.
ASME Section IX is the qualification standard used by the pressure vessel and piping industries. It defines the rules for qualifying welding procedures (WPS/PQR) and welders/operators (WPQ) across all ASME construction codes.
The qualification standard for welding procedures and welders under all ASME construction codes. Organizes base metals by P-Numbers and filler metals by F-Numbers. Essential, supplementary essential, and nonessential variables govern qualification ranges. Used with ASME I, II, III, IV, VIII, and B31 codes.
ASME IX P-Numbers group base metals by weldability characteristics to reduce the number of procedure qualifications needed. F-Numbers group filler metals by usability. Understanding both is essential for determining qualification ranges and allowable substitutions.
Pipeline & Canadian Standards
API 1104 governs cross-country pipeline welding in the United States. CSA W59 governs structural steel construction in Canada. CSA W47.1 governs company certification through the Canadian Welding Bureau. AS/NZS 1554 covers structural steel welding in Australia and New Zealand.
Governs welding of carbon and low-alloy steel pipe for transmission and distribution of petroleum, petrochemical, and natural gas. Uses its own qualification system separate from both D1.1 and ASME IX. Covers both manual and mechanized/automatic welding.
Canadian standard for structural welded steel construction. The Canadian counterpart to AWS D1.1 with some differences in approach to preheat, procedure qualification, and inspection. Used in conjunction with CSA S16 (design) and CSA W47.1 (company certification).
Australian and New Zealand standard for structural steel welding. Covers seven arc welding processes, uses continuous preheat curves based on weldability groups (1–12), and classifies welds into GP (General Purpose) and SP (Structural Purpose) categories.
Governs the certification of companies performing fusion welding of steel structures in Canada. Establishes the company-level quality requirements, supervisor qualifications, and audit processes. Required for structural steel fabrication in most Canadian jurisdictions.
Standard Selection Guide
Choosing the correct welding code depends on the application, structural demands, industry sector, and geographic jurisdiction. Each standard defines its own procedure qualification rules, inspection criteria, and acceptance limits. Use this table to identify which standard governs your project and understand the key differences between codes.
| Standard | Scope | Industry | Geography | Prequalified WPS? |
|---|---|---|---|---|
| AWS D1.1 | Structural steel | Buildings, industrial | United States | Yes |
| AWS D1.5 | Highway bridges | Transportation | United States | NFC only |
| ASME IX | Pressure equipment | Oil & gas, power | Global | No |
| API 1104 | Pipelines | Oil & gas | Global | No |
| CSA W59 | Structural steel | Buildings | Canada | Yes |
| AS/NZS 1554 | Structural steel | Buildings, bridges | Australia/NZ | Yes (SP) |
Compliance Tools
Clause5 provides free compliance calculators for D1.1 (preheat Table 5.11, fillet weld size Table 7.7, carbon equivalent Annex B, heat input, deposition rate), D1.5 (bridge preheat Tables 12.4-12.8), D1.4 (rebar preheat Table 7.2), and CSA W59 (preheat Table 5.3).
Free calculators and reference tools for the most common compliance lookups across these standards.
Look up minimum preheat temperature from D1.1 Table 5.11. Select steel, process, and thickness to get the exact temperature requirement.
Preheat lookup for fracture-critical and non-fracture-critical bridge members per D1.5 Tables 6.3/6.4 and 12.4–12.8.
Preheat lookup based on carbon equivalent and bar size per D1.4 Table 7.2.
Preheat lookup for Canadian structural steel welding per CSA W59:2018 Table 5.3. Select steel grade group, welding process, hydrogen designator, and thickness.
Calculate carbon equivalent (CE) using both the IIW formula and the Pcm formula from your mill test report chemistry.
Calculate arc energy and heat input from voltage, amperage, and travel speed. Supports kJ/in and kJ/mm units.
Look up minimum fillet weld size per D1.1 Table 7.7. Enter material thickness to get the code-required minimum leg size.
Estimate weld metal deposition rate and electrode consumption for common welding processes and filler metals.
Determine required inspection methods (VT, RT, UT, MT, PT) per D1.1:2025 Clause 8 Table 8.2 by joint type, weld category, and loading condition.
What goes into a welding procedure specification under D1.1, when you need one, and the difference between prequalified and non-prequalified WPSs.
When a procedure qualification record is required, what testing is needed, and how essential variables affect re-qualification.
Frequently Asked Questions
AWS D1.1 is the base structural welding code for steel. D1.8 supplements D1.1 with additional requirements for seismic applications, including demand-critical weld designations, CVN toughness testing, and restricted welding procedures for connections in the seismic force-resisting system. D1.8 does not replace D1.1 — it adds to it.
AWS D1.2 covers structural welding of aluminum. It addresses the unique challenges of welding aluminum alloys including hot cracking susceptibility, the maximum preheat and interpass temperature of 250 degrees Fahrenheit (120 degrees Celsius) for heat-treatable alloys, and holding time limits to prevent over-aging. D1.2 permits GMAW, GTAW, PAW-VP, FSW, and SAW but does not permit SMAW.
API 1104 governs welding of pipelines and related facilities. It covers carbon and low-alloy steel pipe used in transmission and distribution systems for petroleum, petrochemical, and gas products. API 1104 uses its own qualification system that is separate from both AWS D1.1 and ASME Section IX.
It depends on the governing code. Structural steel buildings typically use AWS D1.1 (or D1.8 for seismic). Pressure vessels and boilers use ASME IX for welder and procedure qualification. Bridges use AWS D1.5. Pipelines use API 1104. Canadian steel construction uses CSA W59. The engineer of record or contract documents will specify which code applies.