Wire Rope

This information is based on the following regulations and Standards

• OSHA 29 CFR
• MMS CFR
• API SPEC (A
• ANSI/AMSE B 30.9
• Wire Rope Technical Board (Wire Rope Users Manual)

NOTE: Abrasions, Bending, and Crushing represent the ABC’s of wire rope abuse. The primary goal of a good inspection practice is to discover such conditions to maintain that the wire rope remains in service. When any sudden degradation indicates a loss of the original rope strength, a decision must be made quickly.

Qualified Inspector

The decision of to replace or retain wire rope in service must be made by a qualified and experienced inspector.

Two basic questions that need to be answered by the inspector at the time of the inspection prior to use are:

1. Does the rope’s condition present any possibility of failure?

2. Is the rate of deterioration such that the wire rope will be safe to use until the next scheduled inspection?

In order for an inspector to do this, he must:

a. Understand the details of the equipment’s operation
b. Prior knowledge of the frequency of inspection
c. Maintenance history
d. Consequence of failure
e. Historical knowledge of similar equipment

What Causes Wear in Both Groove and Wire Rope?

Wire rope, when loaded, stretches much like a coil spring. When bent over a sheave, the rope’s load-induced stretch causes it to rub against the groove. As a result, both groove and wire are subject to wear. All wire rope operating over sheaves and drums are subjected to cyclic bending stresses, and the rope will eventually fatigue and wear. Fatigue from a cyclic, high magnitude bending stress is the principal reason for shortened rope service. A proper inspection criterion will help determine when the wire life is past its time.

Wire Rope Inspection Criteria

Most Common Causes of Wire Rope Damage

1. Broken Wires
    -Fatigue
    -Insufficient D/d (Sheave diameter to rope diameter) ratios
       • The smaller the ration, the greater the adjusting movement, rapid wear

2. Effects of the Environment
    -Corrosion, core damage, and loss of flexibility

3. Damage due to misuse
    -Kinking worn wires, crushing, bird caging
    -Shock loading, core protrusion

4. Loss of Diameter
    -Wire wear due to incorrect sheave size
    -Core damage

Conclusion:
A qualified rigger is one who has the training, knowledge, and resources to inspect all rigging gear. The ultimate goal is to insure that the rigging gear is safe for the lift and the rigger truly understands the causes for a variety of rigging component failures. It is his responsibility to use "Stop Work Authority" when he / she determine a lift is UNSAFE.

Remember: When in doubt, throw it out!!!!!!!!!!!!!!!!!