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In-pipeline detection method for detecting differential magnetic conductivity based on eddy current under bias magnetization

A dynamic permeability and eddy current detection technology, applied in the direction of material magnetic variables, etc., can solve the problems of inability to detect outer wall defects, placement of large magnetizers, and inability of pipes to be magnetized, etc., achieving easy arraying and modularization. Low consumption and simple structure

Pending Publication Date: 2022-07-19
RES INST OF NUCLEAR POWER OPERATION
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  • Claims
  • Application Information

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Problems solved by technology

To this end, the magnetizer needs to occupy a certain size, and for pipes with small inner diameters, the space is limited, and it is impossible to place a larger magnetizer inside the pipe, so the pipe cannot be magnetized to a near-saturation state, and the outer wall defects cannot Realize detection

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  • In-pipeline detection method for detecting differential magnetic conductivity based on eddy current under bias magnetization
  • In-pipeline detection method for detecting differential magnetic conductivity based on eddy current under bias magnetization
  • In-pipeline detection method for detecting differential magnetic conductivity based on eddy current under bias magnetization

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Embodiment Construction

[0025] The present invention will be described in further detail below with reference to the accompanying drawings and specific embodiments.

[0026] The method of the invention magnetizes the pipeline through a DC magnetizer. Although the pipeline is in a weakly magnetized state, the leakage magnetic field generated by the defects on the outer wall of the pipeline cannot propagate to the inner wall. However, due to the obstruction of the outer wall defects on the magnetizing field, the magnetic field will bypass the defects and gather Above the defect, the magnetic flux density increases. According to the B-H curve of the material, the increase of the magnetic flux density will cause the magnetic permeability of the material to decrease. Therefore, the magnetic permeability will be distorted above the outer wall defect compared to the defect-free position. Due to the magnetic permeability Distortion acts as a hindrance to an applied magnetic field, and this permeability distor...

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Abstract

The invention discloses an in-pipeline detection method for detecting differential magnetic conductivity based on eddy current under bias magnetization, which comprises the following steps of: weakly magnetizing a detected pipeline by adopting a magnetizer, and generating maximum local magnetic induction intensity distortion outside the pipeline or around cracks on the outer wall of the pipeline; the detection probe comprises an eddy current excitation coil and a TMR sensor, the eddy current excitation coil and the TMR sensor are coaxially arranged and are arranged on the inner surface of the pipeline in the normal direction, the eddy current excitation coil generates eddy current on the surface layer of the pipeline, and the TMR sensor is placed in the excitation coil and automatically conducts differential processing on signals. The device and the method have the advantage that the defect of the outer wall is detected under the weak magnetic field condition. The device has the advantages of being simple in structure and high in universality and interchangeability, non-contact rapid automatic detection can be achieved, and the signal-to-noise ratio and sensitivity are high.

Description

technical field [0001] The invention belongs to the field of non-destructive testing, in particular to an in-pipe detection method based on eddy current detection of differential magnetic permeability under biased magnetization. Background technique [0002] Pipelines have been widely developed and applied in the field of nuclear power and petroleum. The pipelines currently used are basically steel pipelines, which are affected by temperature, medium, stress and environment during long-term use. The inner and outer walls of the pipeline are prone to defects such as corrosion, cracks and perforations. Leaks can have serious consequences. More importantly, pipeline leakage and explosion will cause great pollution and harm to the environment, so it is necessary to regularly conduct non-destructive testing on the operation of the pipeline. Magnetic flux leakage inspection is widely used in pipeline inspection due to its advantages of rapid detection of inner and outer wall def...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N27/90
CPCG01N27/90
Inventor 祁攀宫淼龚剑张耀韩孝坤殷宇胡沁宇
Owner RES INST OF NUCLEAR POWER OPERATION
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