AWS D17.1 is the American Welding Society specification for fusion welding of aerospace hardware, and it sorts every weld into Class A, B, or C based on what happens if that weld fails. To buy compliant welds, name the edition and the weld class on your drawing and purchase order, list the inspections you need, and confirm that your supplier’s welders and procedures are qualified to that edition.
What does AWS D17.1 cover?
The full title is Specification for Fusion Welding for Aerospace Applications. It applies to arc welding processes such as gas tungsten arc welding (GTAW, or TIG) and plasma arc welding, and to high-energy beam processes such as electron beam and laser welding. It covers the common aerospace alloy families: carbon and low-alloy steels, stainless steels, aluminum, titanium, and nickel and cobalt alloys.
Many aerospace primes and defense programs call out D17.1 in place of older military welding specifications. Editions change, so always name one. The edition in wide use at the time of writing is D17.1/D17.1M:2017 with later amendments.
D17.1 controls five main areas
- Welder and welding operator qualification, including test welds and a vision exam.
- Procedure qualification, recorded in a Welding Procedure Specification (WPS) and backed by a Procedure Qualification Record (PQR).
- Fabrication rules for joint prep, cleaning, fit-up, tack welds, and repairs.
- Inspection methods, from visual checks to radiography.
- Acceptance criteria, which change by weld class.
How do Class A, Class B, and Class C welds differ?
The weld class tells everyone how much is riding on the joint. The design authority (the engineering group that owns the drawing) assigns it. The welding supplier does not pick it. In plain terms
- Class A: If the weld fails, the aircraft, vehicle, or a major system could be lost, or people could be hurt. This class has the tightest limits and the most inspection.
- Class B: If the weld fails, the system loses some efficiency, but it is not lost and no one is put in danger.
- Class C: If the weld fails, the effect on the system is minor and no one is put in danger.
If a drawing calls out D17.1 but gives no class, stop and ask the design authority in writing. Do not let a supplier guess.
| Weld class | Effect of weld failure | Example parts (design authority decides) | Typical inspection |
|---|---|---|---|
| Class A | Loss of vehicle or major system, or danger to people | Engine mounts, flight-control linkages, primary load paths | Visual, plus surface NDT (penetrant or magnetic particle), plus radiography |
| Class B | Reduced system efficiency, no loss, no danger to people | Ducting, secondary brackets, some fluid lines | Visual, plus surface NDT; radiography when the drawing calls for it |
| Class C | Minor effect, no danger to people | Covers, fairings, non-structural brackets | Visual |
What are the visual inspection requirements?
Visual inspection is the base layer for every class. Every weld gets looked at. Extra methods are added on top of visual, never in place of it. A good visual program covers these points
- 100% of welds, every class. Each weld is inspected over its full length.
- Timing. Inspect after cleaning and before paint, plating, or any coating that could hide a defect.
- Both sides when you can reach them. The root side of a full-penetration joint can hide incomplete penetration, concavity, and oxidation.
- Magnification. Inspectors may use magnification to judge an indication.
- Qualified inspectors. The person who accepts the weld must be qualified under the route your edition and contract allow.
- Titanium color. On titanium, surface color shows how well the weld was shielded. Bright silver passes; darker colors point to contamination.
The inspector checks for cracks, surface porosity, undercut, overlap, incomplete fusion, crater defects, arc strikes, and weld size and profile against the drawing.
How do allowable defect limits change by weld class?
Limits get tighter as you move from Class C to Class A. Many limits scale with material thickness (often written as T), so a single number rarely applies to every part. Use the table below to see how the classes compare. Then pull the actual values from the acceptance table in the edition on your drawing. Do not quote this table on a purchase order.
| Discontinuity | Class A | Class B | Class C |
|---|---|---|---|
| Cracks, any size or direction | Not permitted | Not permitted | Not permitted |
| Incomplete fusion | Not permitted | Not permitted | |
| Incomplete penetration (where full penetration is required) | Not permitted | ||
| Surface porosity, largest single pore | Tightest | Moderate | Loosest |
| Porosity, total in a set weld length | Tightest | Moderate | Loosest |
| Undercut depth | Tightest | Moderate | Loosest |
| Overlap | Not permitted | Not permitted | |
| Arc strikes outside the weld |
Two rules hold across the board. Cracks are rejectable in every class. And a weld that passes visual can still fail radiography, so the class drives the NDT plan, not just the visual limits.
Where does ITAR overlap with D17.1?
D17.1 and ITAR answer different questions. D17.1 asks, “Is this weld good?” ITAR asks, “Who is allowed to see and make this part?” Meeting one says nothing about the other.
The International Traffic in Arms Regulations (22 CFR Parts 120 to 130) are run by the State Department’s Directorate of Defense Trade Controls (DDTC). If your part is a defense article on the U.S. Munitions List, or your drawings are controlled technical data, ITAR applies to your welding supplier too. In practice that means
- The supplier is registered with DDTC. Manufacturers of defense articles must register even if they never export.
- Only U.S. persons see controlled drawings and data unless a license allows otherwise.
- Files, prints, and parts are stored and shipped under access controls.
- Weld procedures, travelers, and inspection records built from controlled drawings may also be controlled. Treat them that way until your export compliance team says otherwise.
Two other programs often show up next to D17.1. AS9100 is the aerospace quality management standard. Nadcap is an industry accreditation for special processes; welding is audited against checklist AC7110. Some primes require Nadcap welding accreditation on top of D17.1.
What should go on your RFQ and purchase order?
Most welding disputes start with a vague purchase order. Use this checklist so every supplier quotes the same job
- Spec and edition. Write “AWS D17.1/D17.1M:[edition]” and any amendments that apply.
- Weld class. Mark the class on the drawing for each weld or weld zone.
- Base metal and filler. List alloy, temper, and material spec, plus the filler spec or “per approved WPS.”
- NDT beyond visual. Name each method and the acceptance standard. Require NDT personnel qualified to NAS 410 or the standard your contract names.
- Qualification records. Say whether you want WPS, PQR, and welder qualification records submitted for approval or just kept on file for audit.
- First article. Call out AS9102 first article inspection if your program needs it.
- Quality system. State AS9100 and Nadcap requirements, if any.
- Export control. Flow down ITAR or EAR clauses and mark controlled drawings.
- Records. Set how long weld and inspection records must be kept, and in what format.
Which materials does D17.1 cover?
D17.1 covers fusion welding of the metals used in aircraft and space hardware: carbon and low-alloy steels, austenitic and precipitation-hardening stainless steels, nickel and cobalt alloys, aluminum and titanium. The standard groups base metals so that a welder certified on one metal can weld others in the same group. A welder certified on a stainless steel, for example, is not automatically certified for titanium or aluminum.
Each family brings its own risks.
- Stainless and nickel alloys: the main concerns are root oxidation, heat tint and hot cracking. Back purging is standard on any joint where the root side is exposed.
- Titanium: titanium picks up oxygen and nitrogen while hot, so the weld and the heat-affected zone must stay shielded until they cool. Trailing shields and full back purges are normal, and the drawing or specification sets the acceptable surface colors.
- Aluminum: the oxide layer must be removed just before welding, usually with AC current and careful cleaning. Porosity from moisture and hydrocarbons is the common defect.
- Precipitation-hardening alloys: heat treatment before and after welding is often part of the procedure, and the drawing usually states the final condition.
Always check the material callout against the shop’s certified procedures and welder groups before you award the job. A shop strong in stainless may not hold current titanium certifications.
How do you prepare for a D17.1 first article?
Most aerospace buyers require a first article inspection (FAI) to AS9102 before production parts ship. The FAI proves that the production process, not a one-off effort, makes a part that meets every drawing requirement. For a welded part, a complete FAI package usually includes
- A ballooned drawing with every characteristic numbered and measured
- Material certifications for base metal and filler, with heat and lot numbers
- The weld procedure used and the welder’s current certification
- Visual inspection results to the weld class on the drawing
- NDT reports, such as penetrant or radiography, where the weld class requires them
- Records of any special processes, such as heat treatment or passivation, from approved sources
Make the first article on the real production setup, with the same fixtures, procedure and welder. If the process changes later, such as a new fixture or a different weld procedure, a partial or full FAI is usually required again. Ask the supplier to confirm how they track those changes.
How does TIGTechs handle D17.1 work?
TIGTechs runs precision TIG welding for aerospace and defense programs from our Dallas, TX shop.
See our aerospace TIG welding services, how we support aerospace and defense manufacturers, and the full list of certifications and compliance programs. Dallas-Fort Worth buyers can also visit our Dallas welding page.
Have a D17.1 drawing ready to quote? Send the print, weld class, and NDT requirements through our request a quote page and we will reply with questions or a price.
Frequently asked questions
No. AWS D1.1 covers structural steel welding for buildings, bridges, and similar structures. AWS D17.1 covers fusion welding of aerospace hardware across steels, aluminum, titanium, and nickel alloys, with acceptance limits set by weld class. A welder qualified to D1.1 is not automatically qualified to D17.1.
The design authority, meaning the engineering group that owns the drawing, assigns the weld class. The welding supplier should never pick the class. If a drawing calls out D17.1 without a class, ask the design authority in writing before work starts.
No. Every weld gets visual inspection, and extra methods such as penetrant, magnetic particle, or radiography depend on the weld class and the drawing. Class A welds carry the most inspection. Confirm the exact methods for each class in the edition on your drawing.
No. ITAR registration with the State Department controls who may access and make defense articles and technical data. D17.1 controls weld quality. A supplier for a defense program often needs both, and you should check each one on its own.
D17.1 keeps a welder’s qualification active as long as the welder keeps using the process within a set time window, and it requires a periodic vision exam. Ask suppliers for continuity logs that show each welder’s recent use of the process.
AWS D17.1 is the welding specification: it says how to qualify, weld, and inspect. Nadcap is an industry audit program that accredits a shop’s special processes, including welding. Some aerospace primes require both, so check your contract.
No. D17.1 covers fusion welding. Resistance spot and seam welding of aerospace hardware is covered by AWS D17.2, and brazing is controlled by separate brazing specifications named on the drawing or purchase order.
Usually yes, within limits. A repaired weld must be re-inspected to the same acceptance criteria as the original. Many drawings and customer quality clauses limit the number of repairs in one area or require engineering approval first, so check before any rework.
