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3. One broken wire within one rope lay length of
any end fitting.
4. Wear of one-third the original diameter of
outside individual wires.
5. Evidence of pitting due to corrosion.
6. Evidence of heat damage from any cause.
7. Kinking, crushing, or any other damage
resulting in distortion of the rope structure.
8. Evidence of internal corrosion, broken wires on
the underside of strands, excessive nicks, or core failure.
Rusting and corrosion of the wires and
deterioration of the fiber core sharply decrease the
strength of a rope. It is impossible to estimate accurately
the loss in strength from these effects.
STORAGE
Most of the following information comes from
chapter 613 of the Naval Ships' Technical Manual
(NSTM). The NSTM contains instructions for the
maintenance, storage, and repair of equipment under
the cognizance of the Naval Sea Systems Command. In
it you can find valuable information not available
elsewhere on the use, care, and upkeep of much of your
equipment. Aboard most ships, the chief engineering
officer has a set of these books.
Wire rope should not be stored in places where acid
is or has been kept. Stress the importance of keeping
acid or acid fumes away from wire rope to all hands at
all times. The slightest trace of acid coming in contact
with wire rope will damage it at that particular spot.
Many times wire rope that has given away at one point
has been found to be acid damaged.
Before storage, wire rope should always be cleaned
and lubricated. If the lubricant film is applied properly
and the wire is stored in a dry place, corrosion will be
virtually eliminated.
LUBRICATION
It is important to lubricate wire rope because wire
is really a mechanical device with many moving parts.
Each time a rope bends or straightens, the wires in the
strands and the strands in the rope must slide upon each
other, so a film of lubricant is needed on each moving
part. Another important reason for lubrication is to
prevent corrosion of the wires and deterioration of the
hemp core.
Clean used wire ropes before you lubricate them.
You can clean them using wire brushes, compressed air,
super-heated steam, JP-5, or turbine oil MIL-L-17331
(2190). Cleaning removes the foreign material and old
lubricant from the valleys between the strands and from
the spaces between the outer wires.
WARNING
When cleaning wire rope with JP-5, you
must wear safety goggles, gloves, and
protective equipment. Work in a well-ventilated
area, preferably open air, to reduce the chance
of vapor inhalation.
CAUTION
You should never soak wire rope in JP-5,
because soaking may remove the lubricants
from the inner wire rope and core. You may,
however, soak wire rope in turbine oil if soaking
is desired.
Lubricant may be applied with a brush, taking care
to work it in well. Another method is to pass the wire
rope through a box containing the lubricant.
The Naval Ships' Technical Manual, chapter 613,
calls for lubricating wire rope with a chain lubricant,
military specification MIL-G-18458 (ships). This
lubricant should be used when possible. When military
specification MIL-G-18458 is unavailable, a medium
graphite grease or even motor oil may be substituted.
Alternative lubricants must come from the PMS list of
alternates. Ordinarily lubricants are applied hot so they
can penetrate the strands and the core more easily.
WIRE-ROPE FAILURE
The following are some common causes of wire-
rope failure:
Using incorrect size, construction, or grade
Dragging over obstacles
Lubricating improperly
Operating over sheaves and drums of inadequate
size
Overriding or crosswinding on drums
Operating over misaligned sheaves and drums
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