You may not know that most areas of your wire rope will be in perfect working condition while some areas are at the point of replacement. The points that require replacement are the parts of the wire rope that bend over a sheave or, during drilling, winds into a drum.
How do you know if an area of your wire rope is worn down?
Why Do Certain Areas Wear Down?
On drill rigs, loads are applied to a winch, and either a rod, piece of casing at a table, or a rod box or rack are picked up. Because of this, the same length of rope will move over the sheave and enter the drum each time an operator applies a load.
Wire rope wears faster if it is subjected to bending. Bending causes the outer wires and inner wires travel at different speeds. Also, loading a wire rope while it’s bending will increase the stress.
Inspections on wire ropes are done in a combination of different visual methods.
The first type of method utilizes a glove or rag. The rag or glove will fully cover your hand while you lightly grasp the wire rope as it moves at a slow speed. Broken wires on the external will stick out, causing it to snag the glove or rag. The rope will be stopped and the inspector will assess the rope’s condition. If a problem is found, the inspector will mark the rope at the concerned location.
This method may cause steel splinters and other hand injuries. There is also a possibility of not finding all wear located on the wire rope.
Another method is the visual-only inspection. In this method, you move the rope 2 to 3 feet and stop to inspect the rope on all sides visually. In areas where grease/grime may cover the rope, clean it with a wire rope because defects may be hiding underneath.
While visually inspecting the rope, bend it to look for “valley breaks.” These are breaks that happen where the strands come in contact with each other. These breaks may be difficult to see without the rope being bent.
Valley breaks typically happen in rope applications that involve small diameter sheaves or sheave grooves that are too small carrying heavy loads. Also, keep an eye out for the areas of the rope that come in contact with drums and sheaves when they pick up loads.
While inspecting wire rope, also be on the lookout for a reduction in diameter. This helps determine the stability of the rope’s core. Two numbers are given upon installation of the rope: the diameter and the length of the rope.
To perform this inspection, place a caliper on the rope’s widest point to read the diameter. Wire ropes are manufactured larger than nominal diameter. When ropes are placed in service their diameter may have a slight reduction. In this case, make the initial measurement of a rope diameter after its first load. A rope should be removed from service if its diameter falls to 95% of its nominal diameter.
A rope’s overall length is just as crucial in determining its health as the diameter. When a core starts to fail, the length of the rope will increase. All increases in rope length are means for replacement.
All these inspections should be done monthly and documented. A daily visual inspection also must be done but does not need to be recorded.
When going through any regular inspection, make sure you are lubricating your wire rope. A wire rope is lubricated during manufacturing, but this initial lubrication is not enough to last the rope’s lifetime.
Lubrication is crucial and is sure to clean and dry the wire rope before applying. Actual lubrication only occurs when the lubricant encounters bare wires. Wire ropes that are used under working conditions should have a lubricant for cable oil. Do not use PB blaster, WD-40, or any crankcase oil.
Here is how to apply lubricant:
- Spray nozzle
Lubrication is essential to a smoothly operating wire rope.
Silver State Wire Rope and Rigging
Silver State Wire Rope and Rigging Inc. is the only company of its kind in Nevada. We have several divisions and expertise in each field. If you have any concerns or questions about your wire rope or need more, call us! We’re happy to answer your questions and inquiries!