Diameter of the rivet to be provided on a 20 mm. thick boiler plate will be __________ mm.

ANS:D - 40

In engineering practice, the diameter of a rivet is usually selected based on factors such as the thickness of the materials being joined, the type of joint, the required strength, and safety considerations. While it's possible to use a larger diameter rivet for thicker plates, excessively large rivets may not be practical or necessary and can lead to inefficiencies in the joint design. Using a rivet with a diameter significantly larger than the thickness of the plate can lead to several drawbacks:

1. Overly Large Hole: Drilling a hole for a larger diameter rivet requires removing more material from the plates, potentially weakening the structure unnecessarily.
2. Material Waste: Using larger rivets than necessary may result in unnecessary material usage and increased manufacturing costs.
3. Weakened Joint: Excessive enlargement of the hole can reduce the effective thickness of the plate around the rivet hole, potentially compromising the structural integrity of the joint.
4. Aesthetics: Large rivet heads may not be aesthetically pleasing, especially in applications where appearance matters.

Therefore, while it's essential to ensure that the selected rivet is appropriate for the thickness and strength requirements of the joint, choosing a rivet diameter that is excessively large relative to the plate thickness is generally not advisable in most engineering applications.