Approach for removing ghost-images in remote field eddy current testing of ferromagnetic pipes.

Luo, Q W; Shi, Y B; Wang, Z G; Zhang, W; Zhang, Y

Luo, Q W; Shi, Y B; Wang, Z G; Zhang, W; Zhang, Y.

Afiliación

Luo QW; School of Automation Engineering, University of Electronic Science and Technology of China, Chengdu 611731, China and Information Geoscience Research Center, University of Electronic Science and Technology of China, Chengdu 611731, China.
Shi YB; School of Automation Engineering, University of Electronic Science and Technology of China, Chengdu 611731, China and Information Geoscience Research Center, University of Electronic Science and Technology of China, Chengdu 611731, China.
Wang ZG; School of Automation Engineering, University of Electronic Science and Technology of China, Chengdu 611731, China and Information Geoscience Research Center, University of Electronic Science and Technology of China, Chengdu 611731, China.
Zhang W; School of Automation Engineering, University of Electronic Science and Technology of China, Chengdu 611731, China and Information Geoscience Research Center, University of Electronic Science and Technology of China, Chengdu 611731, China.
Zhang Y; School of Automation Engineering, University of Electronic Science and Technology of China, Chengdu 611731, China and Information Geoscience Research Center, University of Electronic Science and Technology of China, Chengdu 611731, China.

Rev Sci Instrum ; 87(10): 104707, 2016 Oct.

Article en En | MEDLINE | ID: mdl-27802756

RESUMEN

In the non-destructive testing of ferromagnetic pipes based on remote field eddy currents, an array of sensing coils is often used to detect local defects. While testing, the image that is obtained by sensing coils exhibits a ghost-image, which originates from both the transmitter and sensing coils passing over the same defects in pipes. Ghost-images are caused by transmitters and lead to undesirable assessments of defects. In order to remove ghost-images, two pickup coils are coaxially set to each other in remote field. Due to the time delay between differential signals tested by the two pickup coils, a Wiener deconvolution filter is used to identify the artificial peaks that lead to ghost-images. Because the sensing coils and two pickup coils all receive the same signal from one transmitter, they all contain the same artificial peaks. By subtracting the artificial peak values obtained by the two pickup coils from the imaging data, the ghost-image caused by the transmitter is eliminated. Finally, a relatively highly accurate image of local defects is obtained by these sensing coils. With proposed method, there is no need to subtract the average value of the sensing coils, and it is sensitive to ringed defects.

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Colección: 01-internacional Base de datos: MEDLINE Idioma: En Revista: Rev Sci Instrum Año: 2016 Tipo del documento: Article País de afiliación: China Pais de publicación: Estados Unidos

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