In riveted joint design, to avoid tearing at the plate edge, what should the minimum margin (distance from rivet-hole center to the nearest plate edge) be in terms of rivet diameter d?

Introduction / Context:
Riveted and bolted joints in platework must prevent failure modes such as tearing at the edge, bearing failure, shear of the fastener, and block shear. The “margin” or minimum edge distance ensures that stress concentration around the hole does not initiate cracks or tearing under load.

Given Data / Assumptions:

• d is the rivet (or hole) diameter.
• Plates are ductile and holes are properly finished.

Concept / Approach:
Empirical and code-based recommendations set the minimum margin to provide adequate ligament area from the hole to the edge. Too small a margin risks tearing under tensile load due to stress concentration and reduced net section. A widely adopted rule is to take the margin as at least 1.5 d for riveted joints, providing a robust safety buffer in typical structural steels and pressure parts.

Step-by-Step Solution:

Verification / Alternative check:
Design handbooks and boiler/pressure vessel practices align on m ≈ 1.5 d as a minimum; larger margins may be used for fatigue or corrosion allowances.

Why Other Options Are Wrong:

• 0.5 d or d: Too small; insufficient net ligament, high risk of tearing.
• 2.5 d: Conservative but not a minimum; increases plate size unnecessarily in many cases.

Common Pitfalls:
Ignoring corrosion allowances that reduce effective edge distance, or tolerances that may shift hole placement closer to the edge.

Final Answer:
1.5 d