Which statement best defines a fillet weld and where is it commonly used?

• A. A decorative bead on a flat surface
• B. A weld placed at a corner with no angle
• C. A triangular weld joining two surfaces at right angles; used on lap joints, T-joints, and corner joints
• D. A weld made in a groove between joined members

Answer: (C)

A fillet weld is a triangular cross‑section weld placed along the edge where two pieces meet at an angle, usually around a 90-degree corner, to join them. This type of weld fills the gap between the adjoining surfaces and forms a strong bond along the inside corner where the parts intersect. Because it sits at the junction of two members, it’s ideal for joints like lap joints, T-joints, and corner joints, where there isn’t a groove to fill.

Decorative beads on a flat surface aren’t meant to provide a structural connection. Welds made in a groove between joined members are groove welds, not fillet welds. A weld at a corner with no angle wouldn’t have the typical triangular cross‑section that characterizes a fillet weld.