38 MARCH 2022 WorldWide Drilling Resource® The Importance of Routine Wire Rope Inspection Adapted from Information by WireCo WorldGroup All wire ropes will gradually lose work capability throughout their service life, and eventually wear out. For this reason, periodic inspections are a critical part of overall maintenance. The Occupational Safety and Health Adminstration specifies federal regulations in Standard 1926.1413 - Wire rope - inspection. Regular inspection of wire rope should be performed for three good reasons: 1) It reveals the rope’s condition and indicates the need for replacement. 2) It can indicate if the rope being used is the most suitable for the job. 3) It makes possible the discovery and correction of faults in equipment or operation which can cause costly, accelerated rope wear. All wire ropes need to be thoroughly inspected at regular intervals. The longer it has been in service, the more thoroughly and frequently it should be inspected. Maintaining detailed records for each inspection is a good practice. Inspections ought to be completed by a person who has learned what to look for through special training or practical experience. They should know how to judge the importance of any abnormal conditions. It is the inspector’s responsibility to obtain and follow proper inspection protocols for each application inspected. What to look for: G&O The wire rope shown here has been subjected to repeated bending over sheaves under normal loads, resulting in fatigue breaks in individual wires. These breaks are square and usually in the crown of the strands. Shown here is a single strand removed from a wire rope subjected to strand nicking. This condition is a result of adjacent strands rubbing against one another. While this is normal in a rope’s operation, the nicking can be accentuated by high loads, small sheaves, or loss of core support. The ultimate result will be individual wire breaks in the valleys of the strands. This is a wire with a distinct fatigue break. It is recognized by the square end perpendicular to the wire. The break was caused by a torsion machine used to measure ductility. Breaks of this type are similar to wire failures in the field caused by fatigue. This is an example of fatigue failure of a wire rope subjected to heavy loads over small sheaves. The breaks in the valleys of the strands are caused by “strand nicking.” Crown breaks may also be present. This is what happens when a wire breaks under tensile load exceeding its strength. It is typically recognized by the “cup and cone” appearance at the point of failure. The necking down of the wire at the point of failure to form the cup and cone indicates failure has occurred while the wire retained its ductility.
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