Which statement correctly reflects the relation between concave and convex fillet weld throats?

• A. The Same
• B. Larger For Convex
• C. Smaller For Convex
• D. Equal To The Leg Length

Answer: (A)

The key idea is how a fillet weld’s throat is defined and how it relates to weld size. The throat is the minimum distance from the weld root to the face of the weld along the line that represents the effective weld thickness. For a fillet weld, this thickness is determined mainly by the leg length (the weld size on each member) and the included angle between the pieces being joined. If you keep the leg length the same, changing the surface profile from concave to convex does not change that minimum distance: the throat remains the same because it’s governed by the leg size and the geometry of the joint, not the outward or inward shaping of the weld surface. So concave and convex throats are the same when the leg size is fixed.