In mechanical fastening practice, rivets are generally specified by which primary dimension?

Introduction / Context:
Riveted joints, though replaced by welding in many applications, remain relevant in boilers, pressure vessels, and structural work. Correct specification ensures interchangeability and adequate load capacity. The key identifying dimension used in standards and procurement is important for practice and exams alike.

Given Data / Assumptions:

• Standard solid or semi-tubular rivets.
• Conventional head forms (snap, pan, countersunk, etc.).

Concept / Approach:
Rivet strength correlates with the cross-sectional area of the shank, which resists shear and tension. Consequently, the shank (body) diameter is the most fundamental specification parameter in standards, drawings, and ordering information; lengths are then chosen to suit grip thickness and head style.

Step-by-Step Solution:

Verification / Alternative check:
Design tables list allowable shear per rivet by shank diameter; installation tools and hole sizes are also matched to this diameter, confirming its primacy.

Why Other Options Are Wrong:

• Head diameter and height vary by head style and are secondary.
• Overall length depends on grip thickness and is selected after diameter.
• “None of these” is invalid since a clear standard practice exists.

Common Pitfalls:
Specifying only length without confirming grip range, or ignoring hole tolerance and fit class for the chosen shank diameter.

Final Answer:
Shank diameter