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Detection of Stress due to Corrosion through Passive Measurement and Analysis of Magnetic Fields D Cowell 1, S Staples 2, C Vo 1, P Jarram 3, B Varcoe.

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Presentation on theme: "Detection of Stress due to Corrosion through Passive Measurement and Analysis of Magnetic Fields D Cowell 1, S Staples 2, C Vo 1, P Jarram 3, B Varcoe."— Presentation transcript:

1 Detection of Stress due to Corrosion through Passive Measurement and Analysis of Magnetic Fields D Cowell 1, S Staples 2, C Vo 1, P Jarram 3, B Varcoe 2, S Freear 1 1 School of Electronic and Electrical Engineering, 2 School of Physics and Astronomy, University of Leeds, UK 3 Speir Hunter Ltd, Long Bennington, Newark, UK Booth 429, CORROSION 2013 Information in this presentation is propriety to Speir Hunter Limited. Not to be disclosed without permission.

2 2 Overview Motivation for remote stress measurement Stress Concentration Tomography (SCT) Magnetoelastic effects in steel Experimental measurement of stress-magnetisation Finite element modelling of stress Finite element modelling of stress-magnetisation Experimental magnetic field characterisation rig Prototype SCT instrumentation Initial field survey results STRICTLY PRIVATE AND CONFIDENTIAL

3 3 Motivation Ageing global pipeline infrastructure Non-invasive, remote, pipeline integrity assessment Applicable to non-piggable pipelines Non-interruption of pipeline service No change to operating parameters Detection of stress not geometry STRICTLY PRIVATE AND CONFIDENTIAL

4 4 Stress Concentration Tomography (SCT) Analyse changes in magnetic field along the pipeline Reporting Location of abnormal stresses Metallurgical and mechanical conditions Maximum allowable operating pressure (MAOP) Safe operating term STRICTLY PRIVATE AND CONFIDENTIAL

5 5 Stress Concentration Tomography (SCT) Pipeline experiences stress Corrosion Anomaly Stress Corrosion and Metallurgical Defects Slippage Subsidence Pipeline Anomaly Localised Stress Concentration Magnetostriction Changes in magnetic field STRICTLY PRIVATE AND CONFIDENTIAL

6 6 Stress Concentration Tomography (SCT) Defective section 1 Defective section 2 Defective section 3 Length of anomaly 1 Length of Anomaly 2 Length of anomaly 3 Pipeline Magnetic field STRICTLY PRIVATE AND CONFIDENTIAL

7 7 SCT Instrumentation & Analysis Theory Simulation Experimental Field Trials STRICTLY PRIVATE AND CONFIDENTIAL

8 8 Magnetoelastic effects Joule Magnetostriction Change in sample dimension in the direction of the applied field Villari Effect Change in magnetization due to applied stress STRICTLY PRIVATE AND CONFIDENTIAL

9 9 Stress-magnetisation in carbon steel 2003 Jiles, Li, IEEE Trans. Mag, 39, 3037 STRICTLY PRIVATE AND CONFIDENTIAL

10 10 Experimental Investigation of Stress-Magnetisation in Carbon Steel

11 11 STRICTLY PRIVATE AND CONFIDENTIAL Physical Composition [%wt]Mechanical Properties CSiMnCrNiOthers Tensile Strength [N/mm] Yield Point [N/mm] <0.25 < Stress-Magnetisation in Carbon Steel Experimental Setup 20 x 210 mm rectangular sample #45 Carbon Steel 3 axis fluxgate magnetometer Cyclic force kN MPa

12 12 Stress-Magnetisation in Carbon Steel Processed Experimental Results STRICTLY PRIVATE AND CONFIDENTIAL

13 13 FE Modelling of Magnetic Scalar Potential in Stressed Steel Bar

14 14 FE Modelling of Magnetic Scalar Potential in Stressed Steel Bar FEM of the Magnetic Scalar Potential of the Steel Bar Stressed to 120 MPa STRICTLY PRIVATE AND CONFIDENTIAL

15 15 Comparison between Experimental and FEM Results Experiment image of field compared to model calculated image STRICTLY PRIVATE AND CONFIDENTIAL

16 16 FEM of Cracked Steel Bar STRICTLY PRIVATE AND CONFIDENTIAL

17 17 Magnetic detection of Stress Concentration Zones (SCZ)

18 Characteristic curves of Self Magnetic Flux Leakage (SMFL) SCZ Graphic adapted from: Wang, Z.D., et al., Quantitative study of metal magnetic memory signal versus local stress concentration. NDT & E International, (6): p Magnetic detection of Stress Concentration Zones (SCZ) Methodology - Wang et al STRICTLY PRIVATE AND CONFIDENTIAL

19 19 STRICTLY PRIVATE AND CONFIDENTIAL Magnetic detection of Stress Concentration Zones (SCZ) Instrumentation

20 ΔZ pk magnitude 12.5 μT ΔZ pk-pk length 6 m Magnetic detection of Stress Concentration Zones (SCZ) Analysis of Field Data 48 diameter Gas Pipe at 40 bar ΔX pk magnitude 3 μT ΔX pk length 6 m STRICTLY PRIVATE AND CONFIDENTIAL

21 21 Summary Motivation for remote stress measurement Stress Concentration Tomography (SCT) Magnetoelastic effects in steel Experimental measurement Finite element modelling of stress Finite element modelling of stress induced magnetic field Experimental magnetic field characterisation rig Prototype SCT instrumentation Initial field survey results STRICTLY PRIVATE AND CONFIDENTIAL

22 22 Thank you for your attention


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