Aerospace Welding (D17.1): Classification and Control
What the candidate must understand
D17.1 governs fusion welding for aerospace applications and is built around weld classification and procedure qualification. Candidates must know the weld classes and how class determines the extent of examination and acceptance criteria. Understand the qualification requirements for procedures and welders, the essential variables, and the documentation expected. Know that aerospace work emphasizes process control, material traceability, and cleanliness. Familiarity with the filler-metal and base-metal groupings and the role of the engineering authority in approving procedures is important.
Traps in questions
A common trap is assuming a single acceptance criterion applies to all welds; D17.1 ties criteria to weld class. Another is treating welder qualification as permanent across all classes or processes. Watch for questions about who approves a procedure change and whether examination requirements scale with class. Answers that apply structural steel criteria to aerospace welds are wrong.
Worked example / rule of thumb
Rule of thumb: class first, then criteria. Worked example: a stem describes a weld and asks which examination is required. The correct approach is to identify the weld class, then apply the examination and acceptance requirements for that class rather than defaulting to visual only or to another code's criteria. If the class is not established, the question cannot be answered correctly without it.
Study approach
Build a class-versus-examination table and review the qualification clauses. Then practice identifying the class from a description before selecting criteria.