Define a fillet weld and a groove weld.

• A. A fillet weld fills a triangular area where two surfaces meet at an angle; a groove weld fills a prepared groove between two joint edges.
• B. A fillet weld is a groove; a groove weld is a rounded bead.
• C. A fillet weld requires a groove in the base metal; a groove weld does not.
• D. A fillet weld is used only for butt joints; a groove weld is used only for fillet joints.

Answer: (A)

This question tests how fillet and groove welds join pieces and what their shapes look like. A fillet weld is deposited in the corner where two surfaces meet at an angle, filling a triangular area between the members. It does not require any groove in the base metal—the weld fills the space at the joint’s outside corner or edge.

A groove weld, on the other hand, is made in a prepared groove that runs between the edges of the pieces being joined. The base metal is beveled or otherwise shaped to create a groove, and the weld metal fills that groove to complete the joint from root to top.

So the best description is that a fillet weld fills a triangular area at a joint with angled surfaces, while a groove weld fills a prepared groove between joint edges.