Use wire rope safety assessment by the following standards: the nature and quantity of broken wire; broken wire rope end case; partially broken wire intensity; broken wire growth; strand break situation; rope diameter decreases and the cord break situation; elasticity; external and internal wear; external and internal corrosion; deformation; due to thermal or damage caused by arcing; plastic elongation rate (see animation) and so on.
Rope discard criteria are as follows:
1. Number of broken wires
Rope in any period of broken wire within the pitch reaches the value in Table 6-7, you should promptly scrapped update.
Table 6-7 Number of broken wire rope scrap
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Number of broken wires
Safety factor
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Rope structure
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|||
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Rope 6 × 19
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Rope 6 × 37
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A pitch in the number of broken wires
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||||
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Interactive twist
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Twist the same direction
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Interactive twist
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Twist the same direction
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|
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<6
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12
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6
|
22
|
11
|
|
6-7
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14
|
7
|
26
|
13
|
|
> 7
|
16
|
8
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30
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15
|
Note:
A table is the number of interrupt wire, steel wire, thick wire each equivalent to 1.7 thin wire.
2 per one pitch is the axial distance rope around a week.
2. Corrosion wear, broken wires reduction
Corroded or frayed wire rope should be broken wires in Table 6-7 Table 6-8 reduction, according to the number of broken wires after reduction scrapped.
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Worn or corroded steel surfaces
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10
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15
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20
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25
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30 ~ 40
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> 40
|
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Demolition reduction coefficient
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85
|
75
|
70
|
60
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50
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0
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3. Lifting Hazard halve the number of broken wires
Lifting hot metal or dangerous goods, the number of broken wire rope scrap crane wire rope should be taken generally half the number of broken wire scrap, including wire surface abrasion for the reduction.
4. Broken wire rope ends
When the rope end or near the broken wire (even a small number), if the length of the rope allows, you should cut off the wire parts, re-install.
5. Partially broken wires degree of aggregation
If gathered in less than a broken wire rope length pitch inside, or concentrated in any one strand, the even number of broken wires less than the values listed in Table 6-7, it should be scrapped.
6. The growth rate of broken wire
When the number of broken wires gradually increased its increasingly short intervals, you should carefully check and record the growth of broken wires and fix the rules to determine the retirement date.
7. Whole strand breaks
A whole strand of rope strand breaks, should be scrapped.
8. Wear and tear
When the outer wires worn up to 40%, or due to wear caused by rope diameter is reduced by 7%.
9. Corrosion
Occurs when the wire surface corrosion pit, or rust caused due strand rope diameter increases or decreases.
10. Cord damage
Because cord damage caused by significantly reduced rope diameter, rope core exposed, rope core extrusion.
11. Elasticity
Rope elasticity generally accompanied with the following phenomenon: the rope diameter decreases; rope pitch elongation; wire or decrease the gap between strands; strands appear fine brown powder recess; rope obviously difficult to bend.
12. Deform
Wire rope deformation is visible to lose its normal shape distortion arising from the appearance point of view can be divided into the following categories: wavy, cage distortion strand extrusion, wire extrusion, rope diameter local increase, kink, local is pressed flat, bent.
13. Overheat
Overheating is the rope by arc flashover, burnt, or the appearance that there is a recognizable color change and so on. Arcing rope rope appearance indistinguishable from normal colors, which can easily be hidden.
Destruction of rope performance of various shapes, staggered a variety of reasons, each test should be conducted on the above factors into account, according to the standard master. Before replacing the new rope, the rope to be clear and to eliminate the adverse effects of the device has defects.
