-1- UNRESTRICTED / ILLIMITÉ Field Implementation of a Transient Eddy Current System for Carbon Steel Pipe Thickness Measurements Jeremy A. Buck , Colin Kramer, Jia Lei, and Brian A. Lepine [email protected]613-584-3311 ext. 42359 Canadian Nuclear Laboratories, Chalk River Laboratories Inspection, Monitoring and Dynamics Branch
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-1-UNRESTRICTED / ILLIMITÉ
Field Implementation of a Transient Eddy
Current System for Carbon Steel Pipe
Thickness MeasurementsJeremy A. Buck, Colin Kramer, Jia Lei, and Brian A. [email protected] 613-584-3311 ext. 42359
Canadian Nuclear Laboratories, Chalk River LaboratoriesInspection, Monitoring and Dynamics Branch
• Two scans of each tile hole were performed, rotating the inspection head 45°, for full coverage with both probe types
• TEC measurements collected every 100 mm translating down the pipe
TEC SensorsT1 R2
R1
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Transient Eddy Current (TEC) Testing
• Eddy currents generated via Faraday’s Law:
휀 = −𝑁𝑑𝜑
𝑑𝑡• Broadband voltage pulse used to induce eddy currents
• Eddy currents decay following a diffusion process
• TEC testing much less susceptible to skin effects
Theory
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Analysis Methods
• Signal-to-noise ratio of T/R data hindered analysis, so reflection data was exclusively examined.
• Three analysis techniques were applied to the TEC data:
• Voltage-threshold analysis
• Power-law analysis
• TEC multi-frequency analysis
Overview
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Voltage-Threshold AnalysisMethod
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Voltage-Threshold
• Channels calibrated independently for each scan to compensate for thickness variations around the calibration pipe and slight differences in probe response
• A linear interpolation was used to estimate unknown thickness
%𝑊𝑇 = 100 −𝑊𝑇𝑁𝑂𝑀 −𝑊𝑇𝐼𝐷𝐶𝑁𝑂𝑀 − 𝐶𝐼𝐷
∗ 𝐶𝑁𝑂𝑀 − 𝐶𝑀𝑒𝑎𝑠𝑢𝑟𝑒𝑚𝑒𝑛𝑡
• Assumed thickness and voltage-threshold relationship was linear