Ultrasonic Indication in a Complete-Joint-Penetration Groove Weld
A 1 in. complete-joint-penetration groove weld joins a flange to a web in a fracture-critical tension member. UT by the fabricator's Level II reports a planar indication 0.9 in. long, located 0.35 in. below the surface, oriented transverse to the weld axis. The fabricator's quality manual classifies it as a slag inclusion and proposes acceptance. The owner's inspector notes the member is fracture-critical and that the indication is aligned with the through-thickness direction of the flange. Radiography was attempted but the geometry prevents meaningful coverage. The fabricator asks whether the indication can be accepted as-is or must be excavated.
1. What does fracture-critical status change about the acceptance decision for this indication?
Read the worked answer
Fracture-critical members require the most stringent acceptance criteria and, critically, they require that welds be inspected by the method and extent specified, with no reduction in inspection. A planar indication oriented transverse to the weld axis in a tension member is the least tolerable indication type because it acts as a crack initiator under cyclic tensile stress. The fabricator's classification as slag is a characterization, not an acceptance determination; even if it were slag, planar indications of that size and orientation in fracture-critical tension welds are typically rejectable. The disposition must be based on the applicable acceptance criteria for fracture-critical welds, and the burden is on the fabricator to demonstrate the indication meets them. Acceptance as-is is not supportable without that demonstration.
2. The fabricator argues that because UT is a volumetric method and the indication is small, excavation is disproportionate. Evaluate.
Read the worked answer
Size alone does not govern. The controlling factors are indication type (planar), orientation relative to stress (transverse, in tension), location (subsurface, not inspectable visually), and member classification (fracture-critical). A small planar flaw transverse to a cyclically loaded tension member can propagate; the relevant question is whether the indication meets the acceptance criteria, not whether it is large. Excavation and repair is the proportionate response when acceptance cannot be demonstrated. The inspector should require excavation to sound metal, re-weld per qualified procedure, and re-inspect by UT. The fabricator's proportionality argument is not an acceptance basis under D1.5.
3. What re-inspection must follow repair, and what records should the inspector require?
Read the worked answer
After excavation to sound metal and re-welding, the repaired region must be re-inspected by the same method that detected the original indication - UT - at the same or greater extent, plus visual. Because the member is fracture-critical, the repair procedure and welder qualifications must be verified, preheat and interpass conditions documented, and the excavation depth and extent recorded. The inspector should require the repair WPS, welder qualification records, NDT reports with indication location and sizing, and a disposition record signed by the responsible party. The original UT report and the repair NDT report should be retained together so the history of the location is traceable.