(1) Check for evidence of loose or working rivets.
A working rivet. has movement under structural stress,
but has not loosened so much that you can see movement.
This condition can sometimes be detected by a dark, greasy
residue or damage to paint and primers around rivet heads.
(2) Where possible, replace rivets with the same type as originally
(a) The rivet code designation gives the type of rivet, the
material, the diameter in 32nds of an inch, and the length in 16ths of an inch.
(b) The determination of the length of a rivet is an important
part of any repair.
The length used depends on the grip or combined thickness
of material to be riveted plus a minimum allowance of 1/2 diameter for upsetting
(c) Always use the nearest standard rivet length greater than
the calculated sum.
(3) There are specific considerations in laying out the rivet pattern
for a repair; these rules will apply generally in all instances.
When possible, rivet edge distance, rivet spacing, and
distance between rows should be the same as that of the original installation.
(b) When new sections are to be added, the edge distance
measured from the center of the rivet should never be less than two times the
diameter of the shank.
The distance between rivets or pitch should be at least
three times the diameter; the distance between rows should never be less than
1/2 times the diameter.
(c) Mark the rivet pattern on the metal with a soft pencil to
(4) Rivet holes may be drilled with either a light power drill or a
hand drill (standard shank twist drill).
(a) Before drilling, center-punch all rivet locations. The
center-punch mark should be large enough to prevent the drill from slipping out