Wire Rope Inspection/Replacement

  All wire rope will eventually deteriorate to the point where it must be replaced. The three basic reasons for deterioration are:

1. Abrasion or wear.
2. Corrosion
3. Damage caused by fatigue bending, crushing, kinking, forces or abuse acting against the wire rope during normal usage.

  All wire ropes in active service must be inspected daily. Dated records should be kept on this inspection. This inspection should determine the degree of deterioration at the worst rope lay, as this will determine the suitability of the rope for continued service. By definition, a rope lay is the axial distance along the rope in which one strand makes one complete turn around the rope.

  Conditions such as the following would be reason to question rope safety:

• Evidence of rope deterioration from corrosion should be cause for replacement.
• More than one broken wire in any one strand should be cause for caution. Breaks that occur on the worn crowns of the outside wires indicate normal deterioration. Breaks that occur in the valleys between strands indicate some abnormal condition, possibly fatigue and breakage of other wires that are not readily visible. One or more valley breaks should be cause for replacement.
• Wire breaks generally occur in those portions of wire rope which pass over sheaves, wind onto drums or receive mechanical abuse. Breaks that occur near attached fittings are apt to result from fatiguing stresses concentrated in these localized sections. Breaks of the latter type should be cause for replacement of the rope or renewal of the attachment to eliminate the locally fatigued area.
• Heavy wear or broken wires may occur in sections under equalizer sheaves or other sheaves where rope travel is limited, or in contact with saddles. Particular care should be taken to inspect ropes at these points.
• Rope stretch is generally greatest during initial stages of operation when the strands are becoming adjusted and seated. This is accompanied by some reduction in rope diameter, but not to the extent that the condition of the rope can be judged on this basis.
• Time for rope replacement is indicated by the extent of abrasion, scrubbing, and peening on the outside wires, broken wires, evidence of pitting or severe corrosion, kink damage, or other mechanical abuse resulting in distortion of the rope structure.
• Sheaves, guards, guides, drums, flanges, and other surfaces contacted by wire rope during operation should be examined at the time of inspections. Any condition harmful to the rope in use at the time should be corrected. The same equipment, and particularly sheave and drum grooves, should be inspected and placed in proper condition before a new rope is installed.

  Any of the following listed conditions should be cause for rope replacement.

• In running ropes, six randomly distributed broken wires in one rope lay, or three broken wires in one strand in one rope lay.
• In pendants or standing ropes, evidence of more than one broken wire in one rope lay.
• Abrasion, scrubbing or peening causing loss of more than 1/3 the original diameter of the individual wires.
• Evidence of rope deterioration from corrosion.
• Severe kinking, severe crushing, or other damage resulting in distortion of the rope structure.
• Evidence of any heat damage resulting from a torch or arc caused by contact with electrical wires.
• Reduction from nominal diameter of more than 1/32" for diameters up to and including 3/4". Marked reduction in diameter indicates deterioration of the core resulting in lack of proper support for the load carrying strands. Excessive rope stretch or elongation may also be an indication of internal deterioration.
• Evidence of "bird caging" or other distortion resulting in some members of the rope structure carrying more than others.
• Noticeable rusting or development of broken wires in the vicinity of attachments.

  Recommended professional wire rope inspection services:

Braniff Inspection Services, Inc. (North America)
Contact: Bill Braniff (President)
2013 Beech Court
Golden, CO 80401
Tel.: (303) 232-9426
Fax: (303) 233-6377

Doran Sling (Worldwide)
Contact: Dick Doran
265 Pennsylvania Ave.
Hillside, NJ 07205
Tel.: (908) 355-1101
Fax: (908) 355-5544