Welded Connections MCQ with answer and solution

Concept

The minimum fillet weld size depends on the thickness of the thicker plate. This prevents cracking from fast cooling.

Step-by-step solution

1. Check the minimum fillet weld size table in IS 800:2007, based on the thicker part. 2. Thickness up to 10 mm: 3 mm. 3. Over 10 mm up to 20 mm: 5 mm. 4. Over 20 mm up to 32 mm: 6 mm. 5. Over 32 mm up to 50 mm: 8 mm for the first run. 6. So for a 20 mm to 32 mm plate, the minimum size is 6 mm.

Explanation

A thick plate takes heat away from the weld very fast. A very small weld can then cool too quickly and crack. So the code sets a minimum weld size for each plate thickness range, and for 20 to 32 mm plates it is 6 mm.

Why the other options are wrong

A: 3 mm is for plates up to 10 mm. B: 5 mm is for plates over 10 mm up to 20 mm. D: 8 mm is for plates over 32 mm up to 50 mm.

Shortcut

Remember the sequence 10, 20, 32, 50 mm gives weld sizes 3, 5, 6, 8 mm.

Common mistake

Taking the thinner plate instead of the thicker plate to fix the minimum weld size.