MRT Wirelet

: stephane pernot; Services; 30 May 2017; Hits: 6691; Rating:

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Let's make MRT inspection reliable

Magnetic Rope Testing MRT allows to assess the internal damage of a steel wire rope. Classical peak analysis of wire breaks nevertheless suffers from severe drawbacks which make difficult the analysis of magnetic signals. Standard peak method is for instance limited by some masking effects that can hide neighbouring rope failures. In the end the interpretation of rope damage by rope inspectors can be very confusing and the overall reliability is intrinsically lower than 50%.

Without its correcting lenses, Hubble telescope was almost blind

Wirelets happen to be the corrected lenses for the MRT analysis

Wirelet technology makes it possible to avoid masking effects and enable to zoom into failure signatures in a position-frequency map of magnetic signals called scalogram. Wirelet innovation restores clarity to the MRT method with a detection score of more than 85% and makes it possible to diagnose upstream incipient defects and distributed wear.

MRT inspection

The MRT process is a chain with four links whose reliability is guaranted only when every single link is strong.

Test head

saturated flux
homogeneous field
low dispersion
sensitive coil
digital acquisition

MRT Test

robust procedure
small air gap
visual double check
diameter measurement

Analysis
Wirelet

wire breaks
metallic loss
incipient defects
wear / corrosion
lay length
history of failures

Diagnosis
Report

regulations, standards
residual lifetime
prevention actions
additional test

Anticipating incipient defects

MRT-Wirelet easily points out wire break signatures emerging above rope ground signal and permit to zoom onto low energy features related to incipient defects. It makes it straightforward then to trigger prevention actions to stop the propagation of identiifed failures and to prevent incipient defects from turning into actual wire breaks.

anomalies inside ground signal = developping wear
and 2'. pre-wire break signatures that are not accounted according to standard EN 12927

wear and incipient defects identified inside a wirelet scalogram

Assessing distributed wear and corrosion

Identifying evidences of abnormal fretting-corrosion developing in a wire rope is crucial to sustainably manage the lifetime of a rope. Wirelet innovation permits to

localize wear and distributed corrosion,
compare the evolution of rope damage with previously recorded damage history

MRT-Wirelet is particularly efficient to analyze long splices in sliding evolution or carrying ropes previously in tower section that were relocated.

corrosion of internal layers inside a full locked coil tension rope

Optimizing rope lifetime in fatigue

Wirelet analysis greatly helps to prevent the development of fatigue by identifying very soon numerous incipient wire breaks developping along the rope span. The number of wire breaks due to fatigue is expected to follow an exponential trend function of the number of fatigue cycles. Wirelets enable to influence the future evolution of rope by targeting preventive actions at the right time:fatigue wear with abnormal behaviour : too fast

normal fatigue, 2'. inflection with MRT-Wirelet
rope in ideal operation

Evolution of the number of broken wires verse the number of fatigue cycles

Key points

Reliability and simplicity

- Robust and efficient analysis of MRT signals
- Reliability of the analysis of the magneto-inductive inspection
- Facilitated interpretation for the rope operator
- Extraction of the continuous lay length

Optimization and sustainable management

Issues and customer needs

Services

MRT-Wirelet service comes in 3 formulas

module MRT-0 : peak analysis of MRT signals
module MRT-1 : Wirelet analysis of a splice or a local section
module MRT-2 : Wirelet analysis of full rope span

formulae Reliability +
MRT-Wear : wear and corrosion
MRT-Fat : developping fatigue

formulae Reliability + à la carte
MRT-Geom : anomalies of rope lay length
MRT-Win : crossing with Winspect analysis
MRT-Rot : crossing with Rotation analysis

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