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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. 

Two methods for obtaining edge distance: 

• 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. 

## Rivet Pitch 

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 

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. 

## Rivet Layout Example 

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 

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. 

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