Minimum rivet pitch in a single row

BACKGROUND

Rivet pitch is the distance between the centers of neighboring rivets in the same row, and it is always expressed as a multiple of the rivet diameter. The smallest allowable pitch is three rivet diameters, with the average running from four to six diameters and occasionally reaching as much as ten. The minimum also depends on how many rows are used: one-row and three-row layouts have a minimum pitch of three rivet diameters, while a two-row layout has a minimum of four. Pitch for countersunk rivets is larger than for universal head rivets, and on parts subject to bending moments the spacing is often kept near the minimum to prevent the skin from buckling between rivets. Transverse pitch, the perpendicular distance between rows, is usually 75 percent of the rivet pitch and may not be less than two and one-half rivet diameters.

STUDY TIP

Work these in diameters first and convert to inches last. Keep the three-diameter, four-diameter, and two-and-one-half-diameter figures straight by which layout or dimension each belongs to.

KEY POINTS

• Minimum rivet pitch for one-row and three-row layouts is three rivet diameters; for two rows it is four.
• Three diameters of a 1/8 inch rivet gives 3/8 inch.
• Transverse pitch is usually 75 percent of rivet pitch and never less than two and one-half diameters.

SOURCES

• sources/ama-airframe/ch04.txt "Rivet Pitch"
• sources/ama-airframe/ch04.txt "Transverse Pitch"