Steel rope in CBOS

Condition monitoring of large diameter steel ropes

What we do

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. The research results of this project are currently undergoing a process of commercialization through the TTO Norce Innovation.

Why is this important?

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.

Goals

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

Project outcomes

  • The research results of this project are currently undergoing a process of commercialization through the TTO Norce Innovation.

News

External link

Condition Monitoring of Steel Wire Ropes

By utilising the measurements from a commercial acoustic emission sensor system, a magnetic tester and a camera system for four separate simple bending fatigue tests of steel wire ropes (SWRs), several measurable quantities of the SWRs which indicate deterioration were identified. Based on the processed measurements of a commercial acoustic emission sensor system in one of the tests in this research, the fatigue process of a SWR in a simple bending test is three-phased, with relatively long first- and second phases, showing little- and steady increase in measured signal values, respectively, followed by a shorter phase with a ramp up of signal activity. This three-phase process was recognised in the three other simple bending tests through the processed measurements of a magnetic tester. Changes in the lay length of a SWR were detected using a camera system. Diameter measurements using the same camera system were unsuccessful.

External link

Condition Monitoring Technologies for Steel Wire Ropes – A Review

In this research, we review condition-monitoring technologies for offshore steel wire ropes (SWR). Such ropes are used within several offshore applications including cranes for load handling such as subsea construction at depths up to 3-4000 meters, drilling lines, marine riser tensioner lines and anchor lines. For mooring, there is a clear tendency for using fiber ropes. Especially for heavy-lift cranes and subsea deployment, winches with 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, especially for systems regulated by active heave compensation (AHC). Other sources of degradation are abrasion, fretting, corrosion and extreme forces, and are typically accelerated due to undersized or poorly maintained sheaves, groove type, lack of lubrication and excessive load. Non-destructive testing techniques for SWR have been developed over a period of 100 years. Most notably are the magnetic leakage techniques (electromagnetic methods), which are widely used within several industries such as mining and construction. The content reviewed in this research is primarily the developments the last five years within the topics of electromagnetic method, acoustic emissions (AE), ultrasound, X- and γ-rays, fiber optics, optical and thermal vision and current signature analysis. Each technique is thoroughly presented and discussed for the application of subsea construction. Assessments include ability to detect localized flaws (i.e. broken wire) both internally and externally, estimated loss of metallic cross sectional area, robustness with respect to the rough offshore environment, ability to evaluate both rope and end fittings, and ability to work during operation.