What is the purpose of a fillet gauge in welding inspection?

• A. To measure leg length of a fillet weld.
• B. To test weld ductility with bend test.
• C. To measure coating thickness.
• D. To check welding machine voltage.

Answer: (A)

Measuring the geometry of a fillet weld is the main idea here. A fillet weld forms two slanted legs along the joint faces, and its strength depends on those leg lengths being within the specified size. A fillet gauge provides stepped blades that fit into the fillet profile, so you can read off the length of each leg by which blade sits flush with the weld. This quick check ensures the weld has the proper cross-sectional size according to the design, which in turn supports the required strength and fit-up. It’s not used to test ductility (that’s done with bend tests), not to measure coating thickness, and not to verify welding machine voltage.