slag, porosity, lack of fusion, and incomplete penetration are examples of what type of weld fault?

• A. Structural Discontinuity
• B. Surface Defect
• C. Geometric Error
• D. Crack

Answer: (A)

The key idea is how weld flaws are classified. Slag, porosity, lack of fusion, and incomplete penetration are all flaws that can appear inside the weld or at the weld interface and have the potential to reduce the joint’s ability to carry loads. Because they are defects in the weld that can affect structural performance, they’re categorized as structural discontinuities.

These aren’t merely cosmetic surface issues (some, like porosity, can be internal), and they aren’t simply errors in the weld’s geometry. They’re different from a crack, which is a specific type of flaw, but even cracks fall under the broader umbrella of discontinuities. So the best grouping for these examples is structural discontinuities.