The trace delivers three primary sets of information: • Extent of the occurrence of broken wires. • Amount of steel loss due to wear (cross-sectional area) • Corrosion, damage and abrasion. A trained MRT operator can use the signal (graphic trace) to detect the location of the degradation and assess the severity of the wire rope using visual and MRT evidence. The approximate reduction in rope strength can be accurately estimated. The entire length of the wire rope has to be tested and the complete cross section of the rope can be examined. MRT detects broken wires or corrosion damage on the inside of the rope not visible to an external visual inspection. Wire ropes deteriorate in three distinct stages: STAGE 1: During this stage large numbers of core wire usually in clusters will fail due to fatigue breaks STAGE 2: Eventually, the internal wire rope core (IWRC) will break. This hazardous condition is rarely
detected by visual inspection. In contrast, it is glaringly obvious to the MRT technician (LMI). STAGE 3: As the IWRC fails, the outer strands lose their support which causes secondary fatigue breaks in the wires of the outer strands called “valley breaks”. Detectable only by exceedingly meticulous visual inspection, this is the terminal deterioration phase frequently followed by catastrophic and fatal rope failures. Summary There is an inexplicable lack of knowledge by some Lifting Machine Inspectors/Competent Persons on the uses and benefits of MRT testing. Operational safety depends not only on your equipment, but also on the awareness, skill and performance of the people who
manage and use it. It is often difficult to quantify the cost benefits of training the right people but very easy to count the cost of a disaster, you do not need a wire rope to fail in order to learn. So, become ISO 4309-2017 compliance. For more information regarding the usage, supply and training on Magnetic Rope Testers, do not hesitate to contact Cranemec Group to discuss your needs. Cranemec can offer Engineering Council approved CPD training courses. Cranemec are one of only a few entity’s in Southern Africa offering a complete package when it comes to testing your lifting equipment.
Cranemec Group SA, +27 (0) 16 366 1393, +27 (0) 83 268 4857, info@cranemec.co.za, www.cranemec.co.za
Lifting Africa - Jan/Feb 2020
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INSPECTION & MAINTENANCE
the rope construction. The CPU can be directly connected to a laptop during the inspection or downloaded to a laptop after the inspection and the result will be displayed as a graphical trace.
