Condition monitoring of large diameter steel ropes

The scope of our work is to benchmark the state of the art monitoring technologies such as the electromagnetic method, acoustic emissions, guided wave ultrasound, eddy current, gamma rays, optical and thermal vision systems and current signature analysis, and develop models for robust diagnostics and prognostics.

Several offshore applications use large steel wire ropes including cranes for load handling such as subsea construction at depths up to 4000 meters, drilling lines, marine riser tensioner lines and anchor lines. Especially for heavy-lift cranes and subsea deployment winches, strong ropes of up to 180 mm in diameter may be required, which has a considerable cost per rope, especially for large water depths.

Today’s practice is to discard the rope after a predetermined number of uses due to fatigue from bending over sheaves with a large safety factor. Assessment of the rope is mainly based on visual inspection, which is a tedious and challenging task due to poor observability, because of the outside grease layer and hidden faults within the interior of the rope.

The main goal of this subtask is to gather sufficient scientific evidence for using such techniques to change the existing maintenance regime and challenge the existing discard criteria of steel ropes, moving from regular inspections to onlinecondition monitoring.

The project is a subtask under WP5 Condition Monitoring Technologies under the SFI Offshore Mechatronics