AWS D17.1 is the specification for fusion welding of aerospace hardware: engine parts, fuel and hydraulic lines, airframe and missile structures. Customers often require welds to be made and inspected to D17.1, and Nadcap welding audits look at the same topics.
Weld classes A, B and C
- Class A: the most critical joints, where failure could mean loss of the part or system or a safety risk. Strictest inspection and acceptance.
- Class B: moderately critical joints.
- Class C: non-critical joints.
The design authority sets the class, usually on the drawing or in the specification. The class decides which inspections are needed and which imperfections are acceptable.
The mistakes shops make most
- Assuming a class without asking the customer when the drawing is silent
- Repair welding without a procedure and records
- Losing track of welder qualification and continuity
- No records of cleaning and gas shielding
- Treating D17.1 and Nadcap welding requirements separately
Which of these is in your records?
Knowing the list is easy. The real question is which one sits in your own welds and files. They slip past when read by eye, and auditors look for them first. Upload a weld photo and your WPS to NTB SpecPro and see in minutes which points carry risk, why, and what to do next.
The NTB SpecPro welding module offers AWS D17.1 and D1.1 support as a trial alongside the ISO system. It shows the imperfection type, its likely cause and a fix. Final evaluation stays with your authorized welding engineer.
General information only; does not replace the specification. Use the current revision.
Nadcap® is a registered trademark of the Performance Review Institute.
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