What is a surface discontinuity?

• A. A defect visible on the surface of the weld such as discoloration.
• B. A defect visible on the weld surface such as cracks, porosity, or excessive undercut.
• C. A non-penetrating joint.
• D. A decorative finish.

Answer: (B)

A surface discontinuity is a defect that appears on the weld surface and can be seen without cutting into the weld. The best description includes defects you can visibly observe on the weld itself, such as cracks, porosity, or excessive undercut. These are surface flaws that can affect the weld’s strength and behavior in service, so identifying them by eye is essential during visual inspection.

Discoloration alone isn’t a defined surface discontinuity by itself; it may indicate overheating or contamination but isn’t a specific defect category. A non-penetrating joint describes how the pieces are joined, not a flaw in the weld. A decorative finish is cosmetic and not considered a weld discontinuity.