Machinery's Handbook, 31st Edition
Riveted Joints
1861
RIVETS AND RIVETED JOINTS Riveted Joint Design Classes and Types of Riveted Joints.— Riveted joints may be classified by application as: 1) pressure vessel; 2) structural; and 3) machine member. For information and data concerning joints for pressure vessels such as boilers, reference should be made to standard sources such as the ASME Boiler Code. The following sections will cover only structural and machine-member riveted joints. Basically there are two kinds of riveted joints, the lap-joint and the butt-joint. In the ordinary lap-joint , the plates overlap each other and are held together by one or more rows of rivets. In the butt-joint , the plates being joined are in the same plane and are joined by means of a cover plate or butt strap, which is riveted to both plates by one or more rows of rivets. The term single riveting means one row of rivets in a lap-joint or one row on each side of a butt-joint; double riveting means two rows of rivets in a lap-joint or two rows on each side of the joint in butt riveting. Joints are also triple and quadruple riveted. Lap- joints may also be made with inside or outside cover plates. Types of lap and butt joints are illustrated in the tables on starting at page 1865. General Design Considerations for Riveted Joints.— Factors to be considered in the de - sign or specification of a riveted joint are: type of joint; spacing of rivets; type and size of rivet; type and size of hole; and rivet material. Spacing of Rivets: The spacing between rivet centers is called pitch and between row center lines, back pitch or transverse pitch. The distance between centers of rivets nearest each other in adjacent rows is called diagonal pitch. The distance from the edge of the plate to the center line of the nearest row of rivets is called margin. Examination of a riveted joint made up of several rows of rivets will reveal that after pro gressing along the joint a given distance, the rivet pattern or arrangement is repeated. (For a butt joint, the length of a repeating section is usually equal to the long pitch or pitch of the rivets in the outer row, that is the row farthest from the edge of the joint.) For structural and machine-member joints, the proper pitch may be determined by making the tensile strength of the plate over the length of the repeating section, that is the distance between rivets in the outer row, equal to the total shear strength of the rivets in the repeating section. Minimum pitch and diagonal pitch are also governed by the clearance required for the hold-on (Dolly bar) and rivet set. Dimensions for different sizes of hold-ons and rivet sets are given in the table on page 1870. When fastening thin plate, it is particularly important to maintain accurate spacing to avoid buckling. Size and Type of Rivets: The rivet diameter d commonly falls between d = . t 12 and . d t = 14 , where t is the thickness of the plate. Dimensions for various types of American Standard large ( 1 ∕ 2 -inch diameter and up) rivets and small solid rivets are shown in tables that follow. It may be noted that countersunk heads are not as strong as other types. Size and Type of Hole: Rivet holes may be punched, punched and reamed, or drilled. Rivet holes are usually made 1 ∕ 16 inch (1.6 mm) larger in diameter than the nominal diameter of the rivet although in some classes of work in which the rivet is driven cold, as in automatic machine riveting, the holes are reamed to provide minimum clearance so that the rivet fills the hole completely. When holes are punched in heavy steel plate, there may be considerable loss of strength unless the holes are reamed to remove the inferior metal immediately surrounding them. This results in the diameter of the punched hole being increased by from 1 ∕ 16 to 1 ∕ 8 inch (1.6 to 3.2 mm). Annealing after punching tends to restore the strength of the plate in the vicinity of the holes.
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