What is the minimum effective length of a fillet weld?

What is the minimum effective length of a fillet weld?

• A. 38 mm (1 1/4 in) or 4 times the size of the fillet
• B. 25 mm (1 in)
• C. 50 mm (2 in)
• D. 6 mm (1/4 in)

Answer: (A)

The length of a fillet weld must be long enough to develop the weld’s full strength and avoid end effects at the toes. For fillet welds, the effective length is governed by the weld’s leg size, so the minimum length is four times the fillet size. In practice there’s also a floor: you should not go shorter than 38 mm (1 1/4 in). So the minimum effective length is the greater of four times the fillet size or 38 mm. This is why the correct choice states 38 mm (1 1/4 in) or four times the size of the fillet. Shorter lengths don’t reliably develop the weld’s strength, while longer lengths aren’t required by the standard.

The length of a fillet weld must be long enough to develop the weld’s full strength and avoid end effects at the toes. For fillet welds, the effective length is governed by the weld’s leg size, so the minimum length is four times the fillet size. In practice there’s also a floor: you should not go shorter than 38 mm (1 1/4 in). So the minimum effective length is the greater of four times the fillet size or 38 mm. This is why the correct choice states 38 mm (1 1/4 in) or four times the size of the fillet. Shorter lengths don’t reliably develop the weld’s strength, while longer lengths aren’t required by the standard.