A novel magnetic force transmission eddy current array probe and its application for nondestructive testing of defects in pipeline structures

Eddy current nondestructive testing (ECT) method is an efficient method based on electromagnetic induction for quantitative nondestructive evaluation of defects in the pipeline structure, due to its advantages of high detectability, non-contact and quick scanning. How to realize the probe scanning is a key issue for the long distance pipe inspection when the probe is located inside the tube. To address this problem, in this paper, a novel type of magnetic force transmission eddy current array split type probe has been proposed and developed to detect the defects in the pipeline structure. Firstly, the magnetic force transmission eddy current probe is proposed and designed, which includes excitation device outside the pipe and pickup device inside the pipe. The whole probe can simultaneously move along the pipe under the function of magnetic force. Secondly, the advantage of this proposed split type probe is validated through numerical simulation and experiment, which is that the detection signal cannot be saturated for deep buried defect, compared to the reflection type probe. Thirdly, the array structure pickup probe is designed and its merit is verified through simulation and experiment, which is that the detection sensitivity and efficiency are improved significantly. Finally, the proposed magnetic force transmission eddy current array probe is applied to detect one aluminum pipe with crack defects. The depth, axial position and circumferential position of the cracks can be successfully determined according to the proposed novel probe in this study.