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Finding Broken Wires
Probably the most common sign of rope deterioration and approaching
failure is broken wires. Inspection criteria are specific as to the
number of broken wires allowable under various circumstances.
It is normal for a properly designed and used running (or operating)
rope to exhibit broken wires as it approaches the end of its useful
life. Under ideal conditions, the first wires to break would be the
outside wires at the crowns of the strands where surface wear is expected
to occur. On standing ropes, wire breakage may not be so easily observed.
It is important that a diligent search be made for broken wires, particularly
in critical areas such as pick-up points where stresses are concentrated.
The first step in looking for broken wires is to make sure the surface
is clean enough that breaks can be seen. Wipe with a cloth and if necessary,
scour with a wire brush to clean grease from the valleys between strands.
A thorough search for broken wires cannot be made when a rope is in
tension or is supporting a load. Relax the rope, move the pick-up points
off sheaves, and flex the rope as much as possible.
With a sharp awl, pick and probe between wires and strands, lifting
any wires which appear loose or move excessively.
If you find a number of broken wires approaching the maximum allowable
permitted per strand or per rope lay, extend the search to other sections
of the rope. Also take diameter and lay measurements in the area. If
internal wire breaks or core damage is suspected, an internal examination
should be made.
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