Every operator does visual inspection. Walk along the rope, look for broken wires per lay length, look for corrosion, look for kinks and deformation. ISO 4309 defines the thresholds. Your maintenance team has been doing this for years.
And yet ropes still fail. Not often, but enough that ISO 4309 itself recognises visual is no longer sufficient. The reason is simple: the most dangerous deterioration happens inside.
What visual cannot see
Internal wire breaks. The strands inside a multi-strand wire rope can break in places the surface never reveals. By the time external surface signs appear, the internal breaks may be 10x further along.
Internal corrosion. Moisture and contaminants enter the rope core and corrode the inner strands first. The outside looks fine; the inside is hollowing out.
Loss of metallic area. The total cross-sectional steel can drop below safe levels through a combination of breaks and corrosion that the surface never reveals fully.
What MRT does
Magnetic Rope Testing magnetises the rope and reads the magnetic flux signature as a measuring head moves along the rope. Internal breaks and metallic-area loss show up clearly as flux anomalies. The IAS-T tablet visualises the trace in real time, and offline analysis identifies the exact location of each anomaly along the rope length.
It is non-destructive. The rope keeps running after the test.
It is fast. A typical EOT crane hoist rope tests in under 30 minutes.
It is reportable. The trace is the evidence — your QA team can attach it to statutory records.
Visual + MRT, not visual or MRT
Nobody is recommending you stop visual inspection. The right model is visual on the daily walk-around, MRT on the scheduled maintenance interval. They detect different things and they reinforce each other.
If you only have one inspection method, you have a blind spot.