21 May The Care & Feeding Of Wire Rope
The Care & Feeding Of Wire Rope
Crane activities are among the most sensitive operations a company will ever encounter. Each and every lift must be planned carefully to avoid the risk of serious and costly accidents. Crew members should consider all factors prior to making the lift, including the capacity of the crane, all its rigging, and the condition of its wire rope. Wire rope is designed to be used in a specific manner and must be maintained properly. Allowing wire rope to become damaged or worn can result in possible failure. Avoid wire rope failure by keeping the following practices in mind.
Installing wire rope on the drum: If a reel stand is used, take care that the drum is spooled from the top and that the reel feeds from the top. This avoids causing a reverse bend in the wire. A reverse bend will cause spooling problems and damage the wire rope.
When spooling from a reel, make sure a tension device is used so the reel will not overrun the rope. If using a mallet to align rope as it feeds onto the drum, use one with a plastic or rubber-coated face. Do not strike wire rope with a metal-faced hammer or mallet.
Avoid spooling more wire rope onto a drum than is needed. The last layer must be at least two rope diameters below the drum flange top. Spooling more wire rope than is necessary will increase crushing and may cause the rope to jump the flange.
Prevent kinks in the wire: If a loop forms during unreeling STOP! Pulling on a loop will produce a kink that will not work itself out. A kink is a permanent defect and will cause increased wear on the drum, sheaves and the wire rope itself. If kinks must be cut out of the rope, make sure enough rope remains on the drum to provide 2 or 3 wraps (manufacture’s recommendation) on the drum when the crane is extended full range.
Keep the wire rope lubricated: Rust and dirt can deteriorate and weaken a wire rope. In addition, rust and dirt act as an abrasive on the rope as it spools through the sheaves and drums. Lubrication of the rope allows individual wires to move and work together so that all the wires carry the load instead of just a few. Weather and other exposures can also remove the lubricant and allow rust to form.
When inspecting wire rope, first clean the rope using a wire brush, solvent or steam cleaner. Next, inspect the entire rope for damage in accordance with OSHA 1926.550. Once the rope has passed inspection, lubricate it well. Good lubricants are thin enough to penetrate all the way to the core but thick enough to coat each wire individually.
The best method for assuring proper cleaning and lubrication is to use a manufactured lubrication system. These systems work in the following steps: (1) all corrosion and rust is removed; (2) pressure forces out all moisture; and (3) a high-pressure pump forces lubricant throughout the entire rope.
Take rigging for granted and it could be your downfall! Cranes are only as reliable as each of their rigging components. The capacity of wire rope is based on new or well-maintained rope. Its strength can dramatically decrease if it’s poorly cared for. The rope may look strong, but is it safe? Human life and valuable property may depend upon your answer!