Detection apparatus for defects of inner and outer walls of pipeline based on remote field eddy current testing

Abstract

The invention discloses a detection apparatus for defects of inner and outer walls of a pipeline based on remote field eddy current testing. According to the invention, at the part of a mechanical structure, spring leaves are controlled to stretch and fold so as to make a horizontal part at the top of the spring leaves abut the inner wall of the pipeline; the horizontal part at the top of each spring leaf is provided with a magnetoresistor member for receiving remote field eddy current signals which indicate defects of the inner and outer walls of the pipeline in a remote field; a data processing module outputs electric signals to the magnetoresistor members and calculates phase difference with excitation signals provided by an excitation module as reference signals so as to obtain a plurality of sets of data which indicate defects of the inner and outer walls of the pipeline and enable detection of the inner and outer walls of the pipeline to be completed. According to the invention,arc spring leaves are uniformly circumferentially distributed along a main axis, each magnetoresistor member abuts the inner wall of the pipeline, and the circumference of the pipeline are totally occupied by the magnetoresistor members; therefore, detection of circumferential position and minimal defects of a defective pipeline can be realized, defect detection of overall inner and outer walls of a pipeline is achieved, and parameters of the shape and dimension of a defect is obtained.

Description

technical field [0001] The invention belongs to the technical field of nondestructive testing (nondestructive testing) of far-field eddy currents, and more specifically relates to a detection device for inner and outer wall defects of pipelines based on far-field eddy currents. Background technique [0002] The far-field eddy current effect was discovered in the 1940s. In 1951, Maclean W.R. obtained a US patent for the far-field eddy current effect. The far-field eddy current phenomenon is a special physical phenomenon in eddy current testing. The far-field eddy current phenomenon depends on two effects that occur in the pipeline. One is the shielding effect of the direct coupling magnetic flux of the excitation coil along the inside of the pipeline; the other is the existence of energy The indirect coupling path through the tube wall twice, which originates from the circumferential eddy current induced in the tube wall in the vicinity of the excitation coil, this circumfer...

AI Technical Summary

Problems solved by technology

[0004] Existing detection devices usually have only one receiving coil, which cannot detect the circumferential position of defects and small defects, and obtain parameters such as defect shape and size, with large errors, and the mechanical structure cannot adapt to the size of the pipeline

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