In riveted joints, if a 25 mm hole is drilled in the plates, what shank diameter of rivet should be selected for proper fit and allowance?

Introduction / Context:
Riveted joints require a practical clearance between the drilled hole and the rivet shank to permit insertion and account for slight hole enlargement or burrs. This is addressed by choosing a rivet shank slightly smaller than the drilled hole.

Given Data / Assumptions:

• Drilled hole diameter in plates = 25 mm.
• Standard workshop allowances are assumed.

Concept / Approach:
Common practice keeps the rivet diameter marginally less than the hole (often by about 1–2 mm for sizes in this range) to allow driving or upsetting without excessive force and to ensure proper seating of the rivet head.

Step-by-Step Solution:
1) Start with hole diameter: 25 mm.2) Apply typical clearance: choose rivet shank ≈ 1–2 mm smaller.3) From the options, 23 mm is the practical standard size below 25 mm.

Verification / Alternative check:
Shop practice and handbooks list nominal hole diameters larger than shank diameter to ease insertion and account for slight out-of-roundness. After driving, the shank plastically expands to tightly fill the hole.

Why Other Options Are Wrong:
25 mm gives no insertion clearance.26 mm and 27 mm exceed the hole; insertion without reaming would be impractical.

Common Pitfalls:
Assuming interference is desirable before upsetting; forgetting that plastic expansion during riveting achieves tightness.

Final Answer:
23 mm