[WRE ADVISOR | BUSINESS]
been in out-of-service condition for quite a while—due to lack of proper lubrication. Especially on lattice-type cranes, wire rope needs to be maintained—booms are raised and lowered with it. When it starts to corrode, break within the strand, or even show simple signs of surface wear, steps need to be taken to take care of the problem, because the clock is ticking. Bristow explains how the examination of the failed boom
hoist rope told the story. “Te wire rope had gone without proper lubrication, which was the responsibility of the insured, per the lease agreement.” He imagines that the entire mess could have likely been avoided had the insured taken part in any type of daily inspection of the boom hoist rope, as was required. “Additionally, I noticed broken wires within the rope strands at an average of 6–12 per strand lay. Tis incident could have been prevented.”
ONE BIG MISCONCEPTION IS THAT WIRE ROPE HAS A SET LIFE SPAN.
What Bristow observed, in terms of the strand condition, was basic load cycle wear and tear—which occurs during boom up and boom down functions as part of daily operations. Te gradual breakdown and deterioration of the wires happens as a result of simultaneous compression and expansion of the rope as it travels over the hoist sheaves. A lack of inspection, as well as a lack of knowledge, in terms of knowing what to look for, can easily lead to disaster. As with so many areas of operation within crane and rigging, and any project or piece of equipment that involves wire rope, an enormous amount of man-hours and resources go into making sure operators and crews know what to look for and how to deal with equipment integrity and safety practices. “Tere’s too much at stake, in both human capital and equipment cost, to not take these types of things seriously,” Bristow emphasizes. Ultimately, a standard wire rope can be made up of
hundreds of individual wires. When a rope bends, each of its many wires slides and adjusts to account for the difference in length between the inner and outer bend. Tese individual wires have been fabricated to function at close bearing tolerances to one another. A rope experiences its greatest capacity for stress in relation to the sharpness of a bend, and thus the movement of the individual wires within it. Tough the differences between wire rope manufacturers
are many, the product they fabricate will always possess three basic components: the wires, which form the strands and give the rope its strength; the strands, which spiral around the core; and the core, which is the foundation for the strands. Te differences in wire rope almost always involves the number of strands, how the strands are constructed, the size of the core, and the lay direction of the strands versus the core. In less scientific language, it’s probably easier to explain why most folks purchase wire rope—which is usually determined by four factors: abrasion resistance, fatigue
JR Bristow, of Bristow Truck and Equipment Specialists, emphasizes that improper wire rope maintenance is a simple recipe for disaster.
resistance, flexibility, and strength. It’s give and take at times—in terms of how the buyer will need to determine which of the factors he or she needs more of—but ultimately, most buyers are looking for a healthy balance of all four. One big misconception is that wire rope has a set life
span. It’s actually more about the wear on the rope than the amount of time it’s been in service. Which could have easily been the case in Port Isabel—with the operator assuming the rope didn’t need serviced because it was perhaps “too young” for that—when in fact, it may have been a heavily used piece of equipment, and its wear was much greater than its age. As obvious as it may seem to some, other folks simply
disregard the fact that wire rope needs frequent inspection and maintenance in the same way a crane, or any other type of equipment, does. Bristow reminded the insured of that in Texas, though it was too late. “Inspections should be performed methodically, with an eye on the lookout for corrosion, breaks in wires, and anything that might be deemed questionable,” he asserts—highlighting three of the major culprits in wire rope abuse: abrasion, bending, and crushing. “Te reality is pretty simple: rope will become worn out in any number of ways—overloading, misuse, repeated damage, and lack of maintenance to name a few. It will save companies a ton of money and headaches if they avoid shortcuts and keep a steady eye on the condition of their wire ropes over time. Otherwise, they could end up in a situation they’d just as soon forget.” y
WIRE ROPE EXCHANGE SEPTEMBER-OCTOBER 2014 77
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