A pipeline welder has completed a root pass on a 200 mm diameter pipe. Before proceeding to subsequent passes, they perform a visual inspection. They notice that the weld metal has flowed over the base metal surface at the toe, without fusing into it, creating an unsatisfactory profile. What is this weld discontinuity called?

Question: A pipeline welder has completed a root pass on a 200 mm diameter pipe. Before proceeding to subsequent passes, they perform a visual inspection. They notice that the weld metal has flowed over the base metal surface at the toe, without fusing into it, creating an unsatisfactory profile. What is this weld discontinuity called?

Answer options:

• Incomplete fusion
• Undercut ✅ Overlap
• Excessive convexity

Correct answer: Overlap

Explanation: Overlap occurs when weld metal extends beyond the toe of the weld, creating an angle of less than 90 degrees and not fusing with the base metal. Incomplete fusion describes a lack of coalescence between the weld metal and the base metal or between weld beads.