Recent advances in PEC technology for assessing corrosion under insula7on (CUI) and fireproofing (CUF)

Transcription

1 Recent advances in PEC technology for assessing corrosion under insula7on (CUI) and fireproofing (CUF) Presented by Bruce Stetler 50 th Anniversary of NDTMA conference

2 PEC Working Principle (1/3) PEC measurement consists in 3 steps: 1. The Emission Phase 1 ExcitaIon pulse Time 1 MagneIc response Time 2

3 PEC Working Principle (2/3) PEC measurement consists in 3 steps: 2. The Cut Off 2 ExcitaIon pulse Time 2 MagneIc response Time 3

4 PEC Working Principle (3/3) PEC measurement consists in 3 steps: 3. The RecepIon Phase ExcitaIon pulse 3 Time 3 MagneIc response Time 4

5 A-Scan in Recep7on Phase Early in the A-scan: Eddy currents diffuse as in an infinite wall The decay rate follows a power law relaion : Produces a straight line in a Log-Log scale Produces a rapid drop in a Log-Lin scale Log-Log Scale Log-Lin Scale Voltage - Log scale (v) V t a Voltage - Log scale (v) V t a Time - Log scale (ms) Time - Linear scale (ms)

6 A-Scan in Recep7on Phase Later in the A-scan Eddy currents reach the far side of the WT Voltage - Log scale (v) The decay rate follows an exponenial relaion that: Produces a rapid drop in a Log-Log scale Produces a straight line in a Log-Lin scale Log-Log Scale V e t τ Voltage - Log scale (v) Log-Lin Scale V e t τ Time - Log scale (ms) Time - Linear scale (ms)

7 A-Scan in Recep7on Phase Thinner wall thicknesses change the shape of the A-scan Shorter eddy current diffusion Ime Quicker signal drop in a Log-Log scale Different slope in a Log-Lin scale Log-Log Scale Log-Lin Scale Voltage - Log scale (v) Voltage - Log scale (v) Region of interest with LyZ Time - Log scale (ms) Time - Linear scale (ms)

8 A World of Applica7ons 8

9 What PEC does best DetecIon of corrosion patches At high liz off Through weather jacket (Al, SS, GS) On in-service components (hot or cold) 9

10 What PEC doesn t do well PEC does not detect Cracks Small piang 10

11 Where does PEC fit in the NDE Tool Belt? Permits expansion of inspecion scope and frequency without increasing schedule Can inspect in-service components Monitoring without shut down (high or low temperature components) Does not require removal insulaion or cladding Broader screening permits more focused applicaion of RT and UT 11

12 Measuring Defects Through Insula7on What happens when the probe scans over a defect? Disk Thickness Disk RelaIve Thickness 100% 75% 50% 37.5% 25% 12.5% Measured Thickness 100% 77.2% 49.8% 36.0% 24.9% 13.1% 12

13 Measuring Defects Through Insula7on What happens when the probe scans over a defect? Scanning a defect smaller than the footprint leads to undersizing 13

14 What is Undersizing? Plate WT InsulaIon height Lab mockup sample Flat bovom holes 0.5 (12.7 mm) 2 (50.8 mm) Sample 14

15 What is Undersizing? Lab mockup sample Flat bovom holes Plate WT 0.5 (12.7 mm) A B InsulaIon height 2 (50.8 mm) Defect Diameter Real WT Measured WT A 3 66% 89.5% B 6 33% 66.8% C 3 33% 85.7% C 15

16 What is the signal like when we undersize? Signal - Log Scale (V) Log - Log Scale 2 20 Time - Log Scale (ms) Signal - Log Scale (V) Log - Lin Scale Time - Lin Scale (ms) Nominal + Defect = Actual Signal 16

17 Compensated Wall Thickness Isolate the defect contribuion from the signal We use an analyical equaion for each component of the signal Analyze a defecive region rather than a single data point 17

18 Compensa7ng for the Undersizing Phenomenon Plate WT InsulaIon height Lab mockup sample Flat bovom holes 0.5 (12.7 mm) 2 (50.8 mm) Defect Diameter Real WT Measured WT Compensated WT A 3 66% 89.5% 67.1% B 6 33% 66.8% 36.7% C 3 33% % 39.8%

19 Compensated Wall Thickness on Real Corrosion Scab corrosion Pipe WT InsulaIon 0.35 (8.9 mm) None Sample 19

20 Compensated Wall Thickness on Real Corrosion UT scan from inside 29% 32% 20

21 Compensated Wall Thickness on Real Corrosion PEC scan from outside 57% 29% 32% 52% 21

22 Compensated Wall Thickness on Real Corrosion CompensaIng for undersizing 57% 33% 29% 32% 52% 35% 22

23 Compensated Wall Thickness Measurements Works well at: Any liz off from 0 to 8 Any wall thickness from 0.25 to 2.5 Over any type of weather jacket 23

24 Compensated Wall Thickness Measurements For opimal performance CWT needs: High resoluion scan Well defined defect Good Signal-to-Noise raio data points 24

25 Conclusion PEC is a versaile screening tool for inspecion through insulaion and weather jacket By screening in-service components PEC allows a more focused applicaion of RT and UT CWT addresses the main limitaion of PEC for CUI and CUF inspecions 25

26 Authors: Marc Grenier, Vincent Demers-CarpenIer, Maxime Rocheme, Florian Hardy, Charles Tremblay, Marco Michele Sisto, MarIn Turgeon Presented by Bruce Stetler 50 th Anniversary NDTMA Conference