TECHNOLOGY that helps to give a more accurate assessment of the state of wire ropes without damaging the ropes in the process are a boon for inspectors and companies using this type of equipment.
Regular inspection of wire ropes is critical to avoid catastrophic failure and potential harm. Traditionally, if inspectors were concerned about the state of a wire rope, they would have to inspect it using ‘destructive’ testing where a portion of the rope is unwound or counter-twisted to allow visibility of the inside of the rope.
However, in recent decades there has been significant development in the area of magnetic flux leakage (MFL) technology. Colin Ford, the managing director of Lubrication Engineers (LE) South Africa, and one of the country’s foremost experts on the use of MFL for wire ropes, explains that the technology uses magnetic fields and complex computerised systems to determine the state of a wire rope, right from the centre of the strands to the outer layers of the rope.
“South Africa has been involved in the development of the computer systems used for MFL since the 1980s, so it is fitting to see this technology now being more widely used in South Africa,” says Ford.
LE is the Southern Africa agent for the TST FDSys.P Flaw Detection System, which is a portable steel-wire-rope inspection solution that enables 100% accurate non-destructive inspection of wire ropes with diameters ranging from 6 to 70mm.
The TST portable wire rope tester provides instant, real-time, portable detection of wire rope flaws, and is ideal for inspecting wire ropes in applications like mine hoisters, cranes, elevators, cableways, power grids, suspended bridges and drilling platforms.
How the TST works
The TST portable wire rope tester uses magnetic inductive sensing technology and MFL wire rope inspection techniques. Fault events leave a magnetic signature, which the detector can pick up. This allows for high-speed, accurate and user-friendly inspections.
The TST portable wire rope tester can inspect upwards of 5 m/s (or as limited for safe operation). It offers >90% repeatability of quantitative detection for flaws, and 100% accuracy of severe flaw signals.
Ford explains that the four key things that need to be monitored in wire rope inspections are corrosion, fatigue, abrasion and broken wires. Tools like the TST tester can pick up internal flaws as well as external flaws to ensure that all of these four aspects are thoroughly assessed.
Advantages of MFL testers
Ford says that it’s important to note that these wire rope testers are not meant to replace the essential role that inspectors play, but that they are actually designed to help inspectors do their jobs more effectively and efficiently.
“One of their advantages is their portability. They can be moved from site to site as necessary, or, in instances where there needs to be constant monitoring of a rope, units can be installed for continual inspection,” he says. Their compact size and portability also means that they can be used in spots that may otherwise be difficult to reach or monitor. In addition, they can be used for any length of rope, which makes them versatile.
Although most MFL testers require capital expenditure upfront, they can contribute to overall cost savings over time. As Ford explains, “Around 70% of wire ropes are discarded prematurely because their true state hasn’t been accurately assessed. Using MFL technology can have huge environmental and economic benefits for the industries where wire ropes are used.”
In addition to regular inspections, effective wire rope maintenance also requires that the right type of lubrication be applied in the right quantities and at the correct intervals to extend their lifespans.