A method and device for detecting defects of pipe elbows based on far-field eddy currents

Abstract

A detection method and detection device for pipeline elbow defects based on far-field eddy currents. It mainly solves technical problems such as blind areas or poor probe passability when existing eddy current testing is used for pipe elbows. The main points of the technical solution are: adopting a far-field eddy current sensor composed of two identical excitation units and a receiving unit, and the two excitation units are respectively located on both sides of the receiving unit, and both the excitation unit and the receiving unit are located along the circumference of the elbow cross section of the detected pipeline. The receiving unit is located in the far-field area where the indirect coupled magnetic field signal is measured; when the far-field eddy current sensor is applied with harmonic excitation, the double excitation is used to narrow the far-field area and increase the measured signal amplitude; the sensor is along the circumference of the pipe elbow To scan, measure the phase difference of the signal received by the receiving unit relative to the excitation signal, so as to obtain the change characteristics of the phase difference, that is, to obtain the corrosion and crack defect information at the pipe elbow. It mainly adopts the principle of far-field eddy current and is applied to the defect detection of pipe elbows.

Description

technical field [0001] The invention relates to an electromagnetic non-destructive testing method, in particular to a method and a special device for detecting corrosion or crack defects at pipe elbows based on far-field eddy currents. Background technique [0002] Pipes are widely used in many industries such as oil and gas, chemical industry, electric power and heating, and pipe elbows are an indispensable part of pipeline piping systems. Most pipe elbows are affected by high temperature, high pressure and complex external environment during work, and the inside of the outer curved surface of the pipe elbow is always eroded by the medium during use, resulting in erosion corrosion and thinning of the pipe wall. In addition, under high temperature and high pressure, the pipe elbow wall is prone to cracks. The above defects are easy to expand rapidly under high pressure, causing cracks in the pipe wall at the pipe elbow, which in turn leads to leakage accidents. The conditi...

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Problems solved by technology

[0006] The purpose of the present invention is to overcome various deficiencies existing in the prior art, and to provide a method that utilizes double excitation to narrow the far-field area, increase the amplitude of the measured signal, fully reflect the advantages of far-field eddy current detection, and solve the problem of internal penetration. Far-field eddy current-based detection method and detection device for pipe elbow defects

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