IWRC Ropes: Magnetic Rope Testing (MRT) vs. Visual Inspections
IWRC ropes deteriorate in three distinct stages.
(For details please refer to my paper titled “MRT Inspection of Crane Ropes - Possibilities and Limitations.”).
Stage 1:
As described in my paper, during this stage large numbers of core wires – usually in clusters – will fail due to fatigue breaks.
Easily measurable by MRT, this initial deterioration is not detectable by visual inspections.
Stage 2:
Eventually, the IWRC will break. (Also called ‘complete core failure.’)
This hazardous condition is rarely detected by visual inspections. In contrast, it is glaringly obvious to MRT (http://bit.ly/2J4ss1L).
Stage 3:
As the IWRC fails, the outer strands lose their radial support. This causes secondary fatigue breaks in the wires of the outer strands – called ‘valley breaks.’
Detectable only by exceedingly meticulous visual inspections, this is the terminal deterioration phase frequently followed by catastrophic and fatal rope failures: http://bit.ly/2DG4fM1.
Conclusion:
There is an inexplicable lack of knowledge on, and a reluctance to use MRT even among wire rope professionals (http://bit.ly/2KOOVCK) and http://bit.ly/2Irpkh3).
