A carrier pulsed eddy current detection method and device

Abstract

The invention belongs to the technical field of non-destructive testing, and specifically discloses a carrier-type pulsed eddy current detection method and device. Firstly, a metal plate is installed under the pulsed eddy current sensor, and a square wave excitation is applied to the pulsed eddy current sensor to detect the reduction of the square wave excitation. The attenuation curve of the induced voltage in the pulsed eddy current sensor with time, that is, the carrier signal; then place the metal piece to be tested under the pulsed eddy current sensor with the metal plate installed, and apply square wave excitation to the pulsed eddy current sensor to detect the reduction of the square wave excitation. The attenuation curve of the induced voltage over time in the hourly pulse eddy current sensor, that is, the modulation signal; the original pulse eddy current detection signal of the metal part to be tested is obtained by demodulating the carrier signal and the modulation signal, which solves the problem of pulse eddy current detection of metal components such as thin plates and small-diameter tubes The problem of fast signal attenuation and difficulty in effective acquisition expands the scope of application of pulsed eddy current testing.

Description

technical field [0001] The invention belongs to the technical field of non-destructive testing, and more specifically relates to a carrier-type pulsed eddy current testing method and device. Background technique [0002] In industries such as oil and gas, chemical industry, electric power and heating, metal components such as natural gas pipelines and pressure vessels are prone to large-area corrosion, Defects such as thinning of the wall thickness will cause cracking and leakage or even explosion, causing huge economic losses and causing great pollution and harm to the environment. Pulsed eddy current testing technology has the advantages of on-line detection and can penetrate the cladding layer, and has broad application prospects in the detection of metal component wall thickness thinning defects; The effective detection of metal components such as small-diameter pipes and small-diameter pipes has become a major bottleneck restricting the development of this technology. ...

AI Technical Summary

Problems solved by technology

[0002] In industries such as oil and gas, chemical industry, electric power and heating, metal components such as natural gas pipelines and pressure vessels are prone to large-area corrosion, Defects such as thinning of the wall thickness will cause cracking and leakage or even explosion, causing huge economic losses and causing great pollution and harm to the environment

Pulsed eddy current testing technology has the advantages of on-line detection and can penetrate the cladding layer, and has broad application prospects in the detection of metal component wall thickness thinning defects; The effective detection of metal components such as small-diameter pipes and small-diameter pipes has become a major bottleneck restricting the development of this technology.

[0003] Patent CN104849349A discloses a thin-wall small-diameter pipe weld detection method, which uses phased array ultrasonic combination technology, which can be used to detect thin-wall small-diameter pipe welds with a wall thickness greater than or equal to 3.5mm and less than or equal to 7mm; the method is simple to operate , no radiation, no pollution, the test results are displayed in the form of three-dimensional images, which are intuitive and easy to understand, and are suitable for use as a method for the detection of thin-walled small-diameter pipe welds; The operation of the probe is complicated, the detection efficiency is low, and this method is not suitable for the detection of metal components with cladding

[0004] The Chinese national standard GB / T 28705-2012 stipulates the pulsed eddy current testing method for testing the wall thickness reduction caused by large-scale corrosion without removing the covering layer. It is suitable for testing carbon steel, low alloy steel, etc. In-service components made of ferromagnetic materials with a thickness of 3 mm to 65 mm, a coating thickness of 0 to 200 mm, and a temperature of -150 ° C to 500 ° C, as well as pipes or pipe fittings with a diameter of not less than 50 mm; but for thin plates and fittings with a thickness of less than 3 mm For small-diameter tubes with a diameter of less than 50 mm, due to the rapid attenuation of the detection signal, the acquisition is difficult, and the pulsed eddy current detection method involved in this standard is difficult to achieve effective detection

Images