Figure 42. These plan views and
cross sections show the effects
of
abrasion and peening on wire
rope. Note that a crack has
formed as a result
of
heavy
peening.
abrasion
HOW
TO COUNT BROKEN WIRES
Criteria for wire breaks, provided in Table 14 have been published
by
OSHA,
ASME
and other industry and govemmental organizations for specific applica-
tions.
The
criteria
must
be applicable for the wire rope being inspected.
Allowable
broken
wires are stated either in relation to the rope's lay
or
multi-
ples
of
rope
diameter.
Rope
lay
is one
of
the characteristics
of
wire rope that
needs to
be
understood
by
a qualified inspector. Many industry standards and
government regulations base the broken wire removal criteria
on
the number
of
wire breaks in a specified length
or
distance called a rope lay. Each wire rope has
its
own
particular
lay
length. Just as the initial rope diameter was not determined
until the rope had
been
installed, loaded and, ideally, broken in, the same prac-
tice should
be
followed with regard to the initial rope lay. The initial rope lay
measurement should
be
recorded along with the initial rope diameter measurement.
To measure
one
rope
lay,
mark
a spot
on
one strand, then with a finger, trace
that strand along
one
complete wrap around the rope, then make another mark on
the same strand. This distance beween the marks is one rope lay.
Strand Lay Length
Rope Lay Length
peening
68 • Wire Rope Technical Board - Wire Rope Users Manual, Fourth Edition
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