Concavity of the root surface is detected by ____.

• A. Visual inspection
• B. Destructive testing
• C. Dye penetrant testing
• D. Cutting a cross-section of the weld

Answer: (A)

Concavity of the root surface is a surface-quality attribute best judged by sight. Visual inspection lets you quickly assess the bead profile at the root and determine whether the surface curves inward as intended, without altering or damaging the weld. This non-destructive check is efficient for routine acceptance criteria and relies on proper lighting and viewing angle to see the root contour clearly.

Destructive testing would require cutting or altering the weld, which isn’t practical for simply evaluating root concavity. Dye penetrant testing focuses on surface-breaking defects like cracks and flaws, not the overall geometry of the root bead. Cutting a cross-section does reveal the internal root geometry, but it destroys the weld and is only used when a destructive internal assessment is necessary, not for routine concavity checks.