Welding and Weld Inspection
Procedures and qualification
Girth welds are made under a written welding procedure specification qualified to API 1104, and each welder is qualified within the essential variables of that procedure. The inspector verifies the WPS is available and followed - joint preparation, bevel, root gap, hi-lo, preheat, filler metal, number of passes, heat input, and weather protection such as windbreaks. Welders must requalify after a defined lapse in welding or after a change in essential variables.
Inspection and NDT
Visual inspection applies to 100 percent of welds. Nondestructive testing - radiography, ultrasonic, or automated ultrasonic - is applied at the rates required by the specification, the operator's procedures, and applicable regulation, with tie-ins, road and watercourse crossings, and certain high-stress locations commonly receiving full inspection. Acceptance criteria, repair limits, and cut-out rules come from API 1104 and the project specification.
Documentation
Each weld carries a unique number tied to the welder, joint tally, date, NDT results, and repairs. Weld maps and logs support commissioning and future integrity work.
Traps
Questions often suggest that the inspector qualifies the procedure or the welder (only the qualified procedure and the responsible welding authority do), that visual inspection substitutes for NDT, or that multiple repairs are always acceptable. Watch for hi-lo and gap values quoted as rules of thumb rather than the specification; and watch for the trap of accepting a weld made in rain, high wind, or on a wet bevel without the specified protection.
Worked example
Rule of thumb: if a weld fails NDT twice, expect the specification to require cut-out rather than a third repair. Document the weld number, welder, NDT report, repair record, and final disposition in one traceable chain.