Inspection of steel wire ropes


Examination of steel wire rope before use

During  examination of steel wire ropes attention should be made specifically to the parts of the rope that are, known from experience, to be exposed to wear and damage.

Wear, broken wires, distortion and corrosion are the most common visible signs of deterioration.

Wear is a normal feature of rope service and the correct rope construction ensures that it remains a secondary aspect of deterioration. Correct lubrication of the rope may help to reduce both outer and inner wear.

Broken wires are normal features of rope service towards the end of the rope's life, resulting from bending fatigue and wear. The local break up of wires may indicate some mechanical fault in the equipment. Correct lubrication in service will increase fatigue performance.

Individual broken wires shall be attended to by removing the wire, see figure.

Distortions are usually as a result of mechanical damage, and if severe, can considerably affect rope strength.

Corrosion, both outer and inner, indicate unsuitable grease. Pitting on the external wire surface can result in broken wires. Inner corrosion occurs in some environments when lubrication is inadequate or of a unsuitable type. A reduction in rope diameter will frequently indicate this condition, but confirmation can only be made by an internal examination of the rope.

WARNING! Do not cut the wire, bend it until it breaks  close to the inside of the strajd. This reduces the risk of the ends of wires sticking out of the rope.

Steel wire rope rejection criteria

Discard the wire rope in accordance with current regulations or according to the manufacturers recommendations.

Only a qualified and experienced person should be responsible for discard.

The pictures show typical examples of wire rope deterioration.

WARNING! Failure to take adequate precautions could result in injury.

1. Mechanical damage due to rope movement over sharp edge projection whilist under load.
2. Localised wear due to abrasion on supporting structure. Vibration of rope between drum and jib head sheave.
3. Narrow path of wear resulting in fatigue fractures, caused by working in a grossly oversize groove, or over small support rollers. 
4. Two parallel paths of broken wires indicative of bending through an undersize groove in the sheave.
5. Severe wear, associated with high tread pressure. Protrusion of fibre main core.
6. Severe wear in Langs Lay, caused by abrasion at cross-over points on mulit-layer coiling application.

7. Corrosion of severe degree caused by immersion of rope in chemically treated water.

8. Internal corrosion prominent while external surface shows little evidence of deterioration. Complete lack of strand gap suggests internal degradation.

9. Typical wire fractures as a result of bend fatigue.

10. Wire fractures at the strand, or core interface, as distict from "crown" fractures, caused by failure of core support.

11. Break up of the steel core resulting from higt stress application. Note nicking of wires in outer strands.

12. Strand core protrusion as a result of torsional unbalance created by "drop ball" application (i.e. shock loading).

13. Typical exampel of localised wear and deformation created at a previously kinked portion of rope.

14. Multi strand rope "bird caged" due to torsional unbalance. Typical of build up seen at anchorage end of multifall crane application.

15. Portrusion of steel core resulting from shock loading.

16. Substantial wear and severe internal corrosion. High tension abrasion and corrosive environment are combined in this example.

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