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to Technical Information Main Page |
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General
It is essential to maintain a well planed program of periodic inspections.
In most cases there are statutory and/or regulatory agencies whose requirements
must be adhered to.
Whether or not such requirements exist in your specific environment, you
can be guided by the suggested procedures that follows.
Abrasion, Bending and Crushing represent the ABC's of wire rope abuse, and
it is the primary goal of good inspection practice to discover such conditions
with minimum effort. When any degradation indicates a loss of original rope
strength, a decision must be made quickly to allow the rope to remain in
service. Such a decision can only be made by an experienced inspector. His
determination will be based on:
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| 1) |
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Details of the equipment's
operation |
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| 2) |
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Frequency of inspection |
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Maintenance history |
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Consequences of failure |
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Historical records of
similar equipment |
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Broken
Wires
Shortly after installation
The occasional premature failure of a single wire may be found early in
the rope life and in most cases it should not constitute a basis for rope
removal. Note the area and watch carefully for any further wire breaks.
Remove the broken ends by bending the wire backwards and forwards. In this
way the wire is more likely to break inside the rope where the ends are
left tucked away between the strands. These infrequent premature wire breaks
are not caused by fatigue of the wire material.
During wire rope service (Fatigue Breaks)
The rope must be replaced if a certain number of broken wires are found
which indicate that the rope has reached its finite fatigue life span. See
Broken Wire Discard Tables. |
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Areas to examine
(Based on ISO 4309)
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1)
Examine termination of the rope.
2)
Examine for defective coiling, which causes deformation (flattened
portions) and wear, which can be severe at cross-over positions. (cross-overs
only if multiple layer drums).
3)
Examine for wire breaks.
4)
Examine for corrosion.
5)
Look for deformations caused by snatch loading.
6)
Examine portion which winds over sheave for wire breaks and wear. |
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7)
Check section of rope on equalizer sheave (or compensating pulley)
by lifting up the rope to look at the underside.
8)
Look for deformation.
9)
Check rope diameter against original wire rope diameter. Keep record
of rope diameter measured after break in period. Note that shortly
after installation rope diameter will slightly decrease.
10)
Examine carefully length which runs through lower sheave block, particularly
that section which is in contact with the pulley when the crane is
in a loaded condition.
11)
Examine for wire breaks or surface wear. |
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