SCC DIRECT ASSESSMENT OF CARBON STEEL PIPELINE USING ADVANCED EDDY CURRENT ARRAY TECHNOLOGYA. RAUDE, M. SIROIS, M. BOUCHARD

4th International Conference on Pipeline Integrity Management

Mumbai, India

29-30 January, 2018

Presented by: Anupam Kumar(on behalf of Angélique Raude, Surface Product Manager)

4th ICEPIM & OMIC GAS 2018

CONTENT

1. Context of Development & Objectives

2. Tangential Eddy Current Array (TECA) Technology

3. TECA for SCC Characterization

4. Deployment on Real Samples

5. Conclusion

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1.1 CONTEXT

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• Stress Corrosion Cracking colonies in pipelines

• Specific type of fine, shallow and branched cracking

• Appear as colonies containing many individual cracks

• Represent an integrity threat for in-service pipelines causing failures around the world

• Often, occur under failed coating (no proper CP anymore)

• Cracks essentially parallel one to another and oriented perpendicular to direction of max stress on pipes

• Characterisation challenging for any examination method due to the material and defect type

Current Methods

• In-line inspection

• MFL combines with UT to provide insight of regions with damaged coating, and local environment correlating to SCC

• UT and EMAT for cracks detection and discrimination capabilities

• In-ditch surface inspection

• MPI combined with UT to detection and individually depth size SCC

Objectives

• Detect surface-breaking SCC in carbon steel pipes

• Provide high resolution scan for SCC detection and sizing

• Maximize coverage and speed

• Leverage advanced imaging capabilities (C-Scan, 2D/3D)

1.2 CONTEXT - CURRENT METHODS & OBJECTIVES

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2. TECA TECHNOLOGY (1)

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• Typical TECA response to surface breaking flaws

• EC flow perpendicular to the scan direction and are forced to pass around the longitudinal cracking by either diving underneath it or by going around its extremities

• EC are directly affected by the surface breaking cracking and their associated dimensions

2. TECA TECHNOLOGY (2)

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• Raw EC signal with constant characteristics

• Dedicated software tools

• Simplified probe normalization

• LO monitoring and compensation

• Permeability compensation

• Automated defect sizing

Lift-off

5.0mm deep2.5mm deep1.0mm deep

Lift-off

3mm

2mm

1mm 0mm

Phase shift of 3 indications with no LO

5mm deep defect with LO varying from 0 to 3mm

3. TECA FOR PIPELINE INTEGRITY (1)

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Carbon steel pipelines’ challenges & most advanced inspection solution

seam weld girth weld spiraled weld SCC / ERW

3. TECA FOR PIPELINE INTEGRITY (2)

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TECA performances for fatigue cracking in welds

• POD similar to MT and ACFM

• Detect both axial and transverse cracking in cap, toes and HAZ in one single pass

• Detect crack from 3 mm long by 0.5 mm deep

• Rapid - scanning speed 200 mm/sec

• Accurately size defect from 12.5 mm long by 1 mm deep

• Depth sizing from 0.5 to 7 mm deep

• Cope with lift-off of up to 3 mm (non-conductive paint, coating or air)

3. TECA FOR PIPELINE INTEGRITY (3)

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TECA High Resolution for SCC

• Technology adaptation

• New targeted sizing range: 0.25 to 3.0 mm deep with an accuracy of ±10%

• Large coverage: 71 mm

• Fast inspection: 600 mm/sec

• Lift-off compensation: up to 2 mm

• Conformable to a range of pipeline: from 254 mm of OD

3. TECA FOR PIPELINE INTEGRITY (4)

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Resolution Capabilities

• Solution validated on designed sample

• Section of pipe containing 11 EDM notches

• One long defect with stepped profile(defects 2 to 4)

• Some with dimension outside of solution’ssizing capabilities (defects 7, 8)

• Some placed in close proximity axially(defects 5, 6)

• Some placed in close proximitycircumferentially (defects 10, 11)

• Rapid discrimination of notches 1-2 mm apart axially

3. TECA FOR PIPELINE INTEGRITY (5)

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Resolution Capabilities (cont.)

• Circumferential resolution closer to 3 mm

• Defect profile easily assessed using sideview (defect 2-3-4) and depth assessed

• Defect 2: depth assessed at 1 mm

• Defect 3: depth assessed at 2 mm

• Defect 4: depth assessed at 3 mm

4. DEPLOYMENT ON REAL SAMPLES (1)

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Complete solution used on-site

• Fatigue crack assessment

• Accuracy on isolated crack similar to LPI

• Smallest crack detected at toe (5 mm long)

• Only microns of difference in depth sizing compare to UT measurements

• Crack colony assessment

• Colonies easily displayed with very high definition

• Good correlation with MT mapping

• Discrimination of short cracks in colonies

• Rapid assessment of deepest point

4. DEPLOYMENT ON REAL SAMPLES (2)

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Key performance

• Depth sizing accuracy

• Assessment by gradual grinding of selectedSCC zones and measurement of remaining wallthickness using UT

• Depths measured with TECA were aligned withthe remaining WT assessment: 0.8 mm withTECA, 0.67 mm with ILI and 0.7 to 0.9 mmwith grinding

• Depth sizing repeatability

• Evaluated by scanning the same area 10 times

• Measuring the deepest point each time

• Average deviation was only ±0.08 mm from theaverage depths

4. DEPLOYMENT ON REAL SAMPLES (3)

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Key performance

• Human factor

• 5 known defective areas scanned bythree different operators

• Comparison of depth sizingobtained from each dataset(deepest point at 3 selectedlocations along each scan)

• 15 points assessed

• Depths measured varied from 0.4 to1.8 mm

• Difference in depth sizing variedfrom 0 to 0.3 mm

• Maximum variation seen on colonydetected near a weld

5. CONCLUSION

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• An eddy current array technique has been developedfor the detection and sizing of surface-breakingcracks in carbon steel

• The high-resolution development proved to be adapted to thesentencing of stress corrosion cracking in pipelines

• The technology provides valuable defect depth and lengthmeasurements, but also offers C-Scan imaging with real-time lift-offmonitoring and compensation

• These solutions are being used on-site and demonstrate theircapacity to mitigate potential errors caused by human factors andthose from the unrepeatable results of current methods used in ditchtoday

Thank You. Any Questions?

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