The metal thickness detection using pulsed eddy-current computation and detection method

Zhao, Liang; Li, Chujun; Duan, Zhongxing; Wang, Wei; Wu, Xiaodong

doi:10.1007/s10586-018-2335-4

Cited by 11 publications

(6 citation statements)

References 20 publications

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“…Feature based methods measure plate thickness based on the analysis of signal characteristics. Signal features can be signal phase [24,25] and amplitude [26,27] in sinusoidal ECT or peak value [28,29] and rise time [30,31] in pulsed ECT. Other features include the no-reference-needed feature [32] and the frequency-tozero feature [33].…”

Section: (B)mentioning

confidence: 99%

Characteristics of Eddy Current Attenuation and Thickness Measurement of Metallic Plate

Zeng

Ding

et al. 2019

Chin. J. Mech. Eng.

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In eddy current testing, the law of attenuation of eddy current (EC) is of great concern. In conductive half space under the excitation of uniform magnetic field, the EC density decreases exponentially in the depth direction. However, in conductor with finite thickness tested by coil, the distribution of EC in the depth direction is more complicated. This paper studies the characteristics of EC attenuation in metallic plate of finite thickness. Simulation results show that there is an EC reflection at the bottom of plate, which changes the law of EC attenuation. A new concept, namely the equivalent attenuation coefficient, is proposed to quantify the speed of EC attenuation. The characteristics of EC attenuation are utilized to explain the nonmonotonic relation between coil voltage and plate thickness. Procedure of selecting frequency is discussed. Thereafter, measurement of plate thickness is carried out and accurate result is obtained.

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Section: (B)mentioning

confidence: 99%

Characteristics of Eddy Current Attenuation and Thickness Measurement of Metallic Plate

Zeng

Ding

et al. 2019

Chin. J. Mech. Eng.

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“…As a non-contact detection method, the PEC inspection uses a square wave with a certain duty cycle as the excitation current, which provides a wider investigation depth than conventional eddy current testing [1,2]. In recent years, PEC inspection has been proved to be an effective method for thickness detection and defect diagnosis [3][4][5][6].…”

Section: Introductionmentioning

confidence: 99%

A Novel Pulsed Eddy Current Criterion for Non-Ferromagnetic Metal Thickness Quantifications under Large Liftoff

Wang

Huang

Liu

et al. 2022

Sensors

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The pulsed eddy current (PEC) inspection is considered a versatile non-destructive evaluation technique, and it is widely used in metal thickness quantifications for structural health monitoring and target recognition. However, for non-ferromagnetic conductors covered with non-uniform thick insulating layers, there are still deficiencies in the current schemes. The main purpose of this study is to find an effective feature, to measure wall thinning under the large lift-off variations, and further expand application of the PEC technology. Therefore, a novel method named the dynamic apparent time constant (D-ATC) is proposed based on the coil-coupling model. It associates the dynamic behavior of the induced eddy current with the geometric dimensions of the non-ferromagnetic metallic component by the time and amplitude features of the D-ATC curve. Numeral calculations and experiments show that the time signature is immune to large lift-off variations.

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“…Borehole transient electromagnetic (TEM) [1] techniques are widely used in the field of the nondestructive testing (NDT) of downhole metal casings [2], [3] due to their rapid and accurate acquisition of broad-frequency-range data [4], [5], pulsed eddy-current properties [6], [7], and accessibility to targets [8]. However, the harsh environments of bad borehole conditions, such as the narrow underground confined space [9], cumbersome metal tool housings against the high The associate editor coordinating the review of this manuscript and approving it for publication was Naveed Ur Rehman .…”

Section: Introductionmentioning

confidence: 99%

“…The above methods are based on calibration coefficients to reduce the influence of the nonconstant parameters on borehole measurements. However, they are quite inefficient for borehole TEM systems, as too many measurement data that corresponds to a broad frequency range from early to late sampling times are involved in each signal period of the TEM signal because of the eddy-current diffusion properties in the time domain [3], [13]. Similar to the TEM denoising method in [21] and [22], [23] presented a discrete wavelet transform-based denoising method for borehole TEM data by employing a curve fitting technique.…”

Section: Introductionmentioning

confidence: 99%

EMD-Based Borehole TEM Array Signal Denoising and Baseline Wander Correction for NDT of Downhole Casings

et al. 2020

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Transient electromagnetic (TEM) techniques have been proven to be efficient for nondestructive testing (NDT) operations due to their pulsed eddy-current properties. However, in the field of downhole measurements, harsh environments may significantly influence the NDT performance in downhole casings. In this paper, an empirical mode decomposition (EMD) method based on borehole TEM array signal denoising and baseline wander (BW) correction is proposed to compensate for the bad measurement conditions that affect downhole NDT. Based on the borehole TEM signal model, we investigated the principle of the EMD approach for the borehole TEM response, where the background magnetic noise and temperature drift effects were analyzed by considering the motion measurement and effective permeability. It was found out that although the BW can be effectively removed with the EMD approach, the performance of the signal denoising is closely related to the measurement speed of the downhole NDT sensors. To solve this problem, we proposed an array-based ensemble EMD method to improve the denoising performance of the borehole TEM signals by formulating a three-dimensional borehole TEM data structure, where the generation of the noise-aided data can be more efficient by employing the borehole TEM array. The performance of the proposed method was verified by applying it to a borehole TEM system for the NDTs of oil-well casings. In addition, field experiments were conducted, and the results demonstrated the effectiveness of the proposed method.

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The metal thickness detection using pulsed eddy-current computation and detection method

Cited by 11 publications

References 20 publications

Characteristics of Eddy Current Attenuation and Thickness Measurement of Metallic Plate

Characteristics of Eddy Current Attenuation and Thickness Measurement of Metallic Plate

A Novel Pulsed Eddy Current Criterion for Non-Ferromagnetic Metal Thickness Quantifications under Large Liftoff

EMD-Based Borehole TEM Array Signal Denoising and Baseline Wander Correction for NDT of Downhole Casings

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