3D + 1/16" 4D + 1/16" 3/1/2D + 1/16" 4/1/2D + 1/16" 1 and 3 rows protruding head rivet layout 2 row protruding head rivet layout 1 and 3 rows countersunk head rivet layout 2 row countersunk head rivet layout 3D 4D 3/1/2D 4/1/2D Rivet Spacing Preferred Spacing Minimum Spacing Figure 4-80.  Rivet spacing.  the edge distance minimums. Add  1 ⁄ 16-inch to the minimum  edge distance or determine the edge distance using the next  size of rivet diameter.  off the rivet pitch (distance between rivets), as shown in  Figure 4-81 . In a two-row layout, lay off the first row, place  the second row a distance equal to the transverse pitch from  the first row, and then lay off rivet spots in the second row  so that they fall midway between those in the first row. In the  three-row layout, first lay off the first and third rows, then  use a straightedge to determine the second row rivet spots. When splicing a damaged tube, and the rivets pass completely  through the tube, space the rivets four to seven rivet diameters  apart if adjacent rivets are at right angles to each other, and  space them five to seven rivet diameters apart if the rivets  are parallel to each other. The first rivet on each side of the  joint should be no less than 2 1 ⁄ 2 rivet diameters from the end  of the sleeve.  Two methods for obtaining edge distance:  Rivet pitch is the distance between the centers of neighboring  rivets in the same row. The smallest allowable rivet pitch is 3  rivet diameters. The average rivet pitch usually ranges from  4 to 6 rivet diameters, although in some instances rivet pitch  could be as large as 10 rivet diameters. Rivet spacing on parts  that are subjected to bending moments is often closer to the  minimum spacing to prevent buckling of the skin between  the rivets. The minimum pitch also depends on the number of  rows of rivets. One-and three-row layouts have a minimum  pitch of 3 rivet diameters, a two-row layout has a minimum  pitch of 4 rivet diameters. The pitch for countersunk rivets  is larger than for universal head rivets. If the rivet spacing  is made at least  1 ⁄ 16-inch larger than the minimum, the rivet  hole can be oversized without violating the minimum rivet  spacing requirement.  [Figure 4-80] Transverse pitch is the perpendicular distance between rivet  rows. It is usually 75 percent of the rivet pitch. The smallest  allowable transverse pitch is 2 1 ⁄ 2 rivet diameters. The smallest  allowable transverse pitch is 2 1 ⁄ 2 rivet diameters. Rivet pitch  and transverse pitch often have the same dimension and are  simply called rivet spacing. The general rules for rivet spacing, as it is applied to a  straight-row layout, are quite simple. In a one-row layout,  find the edge distance at each end of the row and then lay  Figure 4-81.  Rivet layout. Rivet Pitch •  The rivet diameter of a protruding head rivet is  3 ⁄ 32- inch. Multiply 2 times  3 ⁄ 32-inch to obtain the minimum  edge distance,  3 ⁄ 16-inch, add  1 ⁄ 16-inch to yield the  preferred edge distance of  1 ⁄ 4-inch.  •  The rivet diameter of a protruding head rivet is  3 ⁄ 32-inch.  Select the next size of rivet, which is  1 ⁄ 8-inch. Calculate  the edge distance by multiplying 2 times  1 ⁄ 8-inch to get  1 ⁄ 4-inch.  Transverse Pitch Rivet Layout Example Rivet pitch (6 to 8 diameters) Edge distance (2 to 2$^{1}$/2 diameters) Transverse pitch (75 percent of rivet pitch) Single-row layout Two-row layout Three-row layout 4-35