Riveted Joints 151
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Pressure may be applied to form the second rivet head, either by direct hammering or
through hydraulic or pneumatic means. While forming the rivet head, the shank will bulge
uniformly. Hence, a certain amount of clearance between the hole and shank must be provided
before riveting (Fig. 10.1 (b)).
Hot riveting produces better results when compared to cold riveting. This is because,
after hot riveting, the contraction in the shank length tends to pull the parts together, making
a tight joint.
10.2.3 Caulking and Fullering
Riveted joints must be made air tight in applications such as boilers and other pressure vessels.
Caulking or fullering is done to make the riveted joints air tight.
10.2.3.1 Caulking
The outer edges of the plates used in boiler and other pressure vessels are bevelled. To produce
air tight riveted joints, these bevelled edges of the plates are caulked. Caulking is an operation
in which the outer bevelled edges of the plates are hammered and driven-in by a caulking tool.
The caulking tool is in the form of a blunt edged chisel (Fig. 10.2a).
10.2.3.2 Fullering
Similar to caulking, fullering is also used to produce air tight joints. Unlike the caulking
tool, the width of the fullering tool is equal to the width of the bevelled edges of the plates
(Fig. 10.2 (b)).
Caulking and fullering operations are carried out effectively by applying pneumatic
pressure.
Caulking toolCaulked plate
10°
(a)5°
(b)Fullering toolFig. 10.2 (a) Caulking (b) Fullering