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

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...

AI Technical Summary

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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