An eddy current detection method for the thickness of the corrosion layer on the inner wall of the austenitic pipe
An eddy current testing and austenitic tube technology, which is applied to the eddy current testing of the thickness of the inner wall of the austenitic tube, and the measurement of the thickness of the inner wall of the corrosion layer of the in-service heat-resistant austenitic stainless steel tube. There are problems such as deviation in the measurement value of the Hall sensor, so as to achieve the effect of accurate measurement results, improved detection sensitivity and wide application range
Active Publication Date: 2022-04-12
INST OF METAL RESEARCH - CHINESE ACAD OF SCI
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However, this method is relatively complicated, and it is not easy to operate in the field, and it is affected by the bias magnetic field, and the measured value of the Hall sensor will be biased.
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[0027] The structure of the eddy current detection probe used is as follows: figure 1 As shown, the excitation coil 2 and the receiving coil 5 are isolated by the magnetic box 6 to eliminate the influence of the mutual inductance of the two coils on the detection result.
[0028] The structural structure of the pipeline to be inspected is as follows: figure 2 As shown: the heat-resistant austenitic stainless steel has been in a high-temperature and high-pressure working environment for a long time, and the outside of the pipe wall is oxidized to form an oxide layer 13; the inside of the pipe wall will be corroded (carbonized) to form a corrosion layer 11; most of the other pipe walls It still exists in the form of austenite matrix 12.
[0029] Such as image 3 As shown, during on-site measurement, the outer surface of the pipe wall is simply cleaned to make it as smooth as possible, and then the eddy current detection probe is attached to the pipe wall to be tested for eddy...
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The purpose of the present invention is to provide an eddy current detection method for the thickness of the corrosion layer on the inner wall of the austenitic pipe, specifically: firstly use the high-frequency eddy current signal to measure the austenitic pipe wall, determine the thickness of the oxide layer on the outer wall of the pipe, and then draw the sample The linear relationship diagram between the thickness of the oxide layer on the outer wall of the tube and the amplitude of the high-frequency eddy current detection signal; then based on the high-frequency measurement results, the sample tube is measured by using the low-frequency eddy current, and the corrosion layer thickness and the eddy current The linear relationship diagram of the detection signal amplitude; finally, through the functional relationship between the measured value under the low-frequency eddy current condition and the calibration curve, the specific corrosion layer thickness value of the measured pipe wall is solved. The invention uses two kinds of eddy current signals of high frequency and low frequency to detect the austenite tube, and the thickness of the inner wall corrosion layer can be obtained through signal processing and calculation. This method is simple and efficient, and has a wider scope of application.
Description
technical field [0001] The invention belongs to the field of non-destructive testing, and relates to an eddy current testing method for the thickness of the corrosion layer on the inner wall of an austenitic pipe, which is mainly aimed at the corrosion layer on the inner wall of a heat-resistant austenitic stainless steel pipe in service in thermal power plants, nuclear power, petrochemical and other fields Measurement of thickness. Background technique [0002] Heat-resistant austenitic stainless steel has high strength at high temperature, good steam oxidation resistance, good furnace surface corrosion resistance and sufficient structural stability, and is widely used in hydrogen conversion furnaces, ethylene cracking furnaces, etc. Its general working temperature is 600°C-1000°C, and the pressure is 2-3Mpa. In the long-term high-temperature and high-pressure working environment, corrosion products will inevitably be produced on the inner wall of the pipe. The loose struc...
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IPC IPC(8): G01B7/06G01N27/90
CPCG01B7/10G01N27/90G01N27/9006
Inventor 蔡桂喜张双楠李宏伟张博李建奎张宝俊杨亮刘芳
Owner INST OF METAL RESEARCH - CHINESE ACAD OF SCI