Method for jointly detecting corrosion defect of pressure pipeline by utilizing multiple guided wave modes

Abstract

The invention discloses a method for jointly detecting corrosion defects of a pressure pipeline by utilizing multiple guided wave modes, relates to an ultrasonic non-destructive testing technology, and is used for solving the problem that the accuracy is relatively low when a single guided wave mode is used for detecting. The method for detecting the corrosion defect of the pressure pipeline comprises the following steps: calculating ultrasonic guided wave dispersion data of the pressure pipeline, and determining the center frequency of a transducer according to the dispersion data; the method comprises the following steps: arranging ultrasonic transducer annular arrays on two sides of a to-be-detected pressure pipeline, and acquiring ultrasonic guided wave data detected by the pressure pipeline in an L (0, 1) mode and a T (0, 2) mode; preprocessing the array waveform data to obtain detection data which can be used for guided wave imaging; according to the L (0, 1) mode guided wave data, a full waveform inversion method is adopted to invert the wall thickness of the pipeline corrosion defect; judging whether the pipeline defect exceeds the detection depth range of the T (0, 2) mode, and if the pipeline defect exceeds the detection depth range, ending; and if not, inverting the wall thickness of the pipeline corrosion defect by adopting a full-waveform inversion method according to the T (0, 2) mode guided wave data.

Description

Technical Field

[0001] The invention relates to the technical field of ultrasonic nondestructive testing, and in particular to a method for jointly detecting corrosion defects of pressure pipelines by utilizing multiple guided wave modes. Background Art

[0002] At present, pressure pipelines play a vital role in the petroleum, chemical, natural gas and other industrial fields, and their safety is directly related to the stable operation of the production system. However, as the pipelines serve for a long time, the inner wall of the pipeline will gradually become thinner due to corrosion, wear and other factors, thereby increasing the risk of pipeline leakage or even bursting.

[0003] In order to ensure the structural integrity of pressure pipelines, timely and accurate detection of pipeline wall thickness has become a key link in safety management. Although traditional wall thickness detection methods, such as ultrasonic thickness measurement and radiographic detection, can provide a certain degree of detection accuracy, their detection efficiency is low, they cannot cover large areas of pipelines, and have certain limitations when used in complex environments.

[0004] In the existing technology, ultrasonic guided wave technology is an emerging non-destructive testing method that can achieve large-scale detection through long-distance propagation of the pipeline wall. The propagation characteristics of guided waves are closely related to the change of pipeline wall thickness. Therefore, by analyzing the characteristics of guided wave signals, the state of pipeline wall thickness can be evaluated. Compared with more traditional point detection, guided wave detection can cover a larger range, reduce detection time, and avoid direct contact with the pipeline surface.

[0005] However, the inventors of the present application have discovered that a single waveguide mode may suffer from problems such as insufficient sensitivity or complex signal reflection when encountering complex structures or material characteristics, resulting in inaccurate detection results. Summary of the invention

[0006] The purpose of the present invention is to provide a method for jointly detecting corrosion defects of pressure pipelines using multiple waveguide modes, so as to solve the technical problem of low accuracy in existing single waveguide mode detection.

[0007] In order to achieve the above object, the present invention adopts the following technical scheme: A method for jointly detecting corrosion defects in pressure pipelines using multiple guided wave modes comprises the following steps: Step S1, calculating the dispersion data of the ultrasonic guided wave of the pressure pipeline, and determining the center frequency of the transducer according to the dispersion data; Step S2, arranging an ultrasonic transducer ring array on both sides of the pressure pipeline to be tested, and acquiring ultrasonic guided wave data of L (0, 1) mode and T (0, 2) mode pressure pipeline detection; Step S3, preprocessing the array waveform data to obtain detection data that can be used for guided wave imaging; Step S4, inverting the wall thickness of the pipeline corrosion defect using a full waveform inversion method based on the L (0, 1) mode guided wave data; Step S5, judging whether the pipeline defect exceeds the detection depth range of the T (0, 2) mode, if it exceeds the detection range, then the process ends; if it does not exceed the detection range, then proceed to the next step; Step S6: invert the wall thickness of the pipeline corrosion defect using the full waveform inversion method based on the T (0, 2) mode guided wave data.

[0008] In actual application, step S1 specifically includes the following steps: Step S11: Through theoretical analysis of the ultrasonic propagation characteristics of the pressure pipeline, the dispersion equations of ultrasonic Lamb waves of different mode waves can be obtained: ; in, represents the angular frequency, is the wave number of the ultrasonic Lamb wave, is the thickness of the pressure pipe, Represents the elastic parameters of the pressure pipe; the dispersion data of different mode waves can be obtained by solving the dispersion equation; Step S12: Solve the dispersion equation using the dichotomy method to obtain phase velocity dispersion data, and use the frequency that changes faster with the phase velocity as the basis for selecting the main frequency of the ultrasonic transducer.

[0009] Specifically, step S3 includes the following steps: Step S31, setting the starting point and end point of the time window for selecting a specific waveguide mode according to the dispersion data and the distance between the sound source and the receiver: ; in, Indicates the starting point of the time window. is the distance between the transmitting and receiving transducers, It represents the group velocity of the guided wave at the center frequency of the transmitting transducer and is calculated as follows: , represents the end point of the time window, is the duration of the signal used to excite the transmitting transducer; Step S32: After the start and end points of the time window are determined, the time window function can be designed. , for the original measured signal Multiply to obtain waveform data that can be used for guided wave imaging .

[0010] Furthermore, the step S5 specifically includes the following steps: Step S51: judging the minimum wall thickness of the pressure pipe that can be detected by the T (0, 2) mode according to the guided wave dispersion data calculated in step S1: ; in, Indicates the minimum wall thickness of the pressure pipe that can be detected by the T (0, 2) mode. is the original thickness of the pressure pipe, represents the cutoff frequency of the T(0,2) mode, represents the cutoff frequency of the T(0,3) mode; Step S52: compare with the minimum pressure pipe wall thickness inverted by L (0, 1) mode, if it satisfies If the condition is met, step S6 is executed; in, Indicates the minimum wall thickness of the pressure pipe for L(0,1) mode inversion.

[0011] Compared with the prior art, the method for detecting corrosion defects of pressure pipelines by using multiple guided wave modes in the present invention has the following advantages: In the method for jointly detecting corrosion defects of pressure pipelines using multiple waveguide modes provided by the present invention, the center frequency of the transducer is determined according to the dispersion data by calculating the dispersion data of ultrasonic waveguide waves of pressure pipelines; an annular array of ultrasonic transducers is arranged on both sides of the pressure pipeline to be tested to obtain ultrasonic waveguide wave data of pressure pipeline detection in L (0, 1) mode and T (0, 2) mode; the array waveform data is preprocessed to obtain detection data that can be used for waveguide imaging; the wall thickness of the pipeline corrosion defect is inverted by the full waveform inversion method according to the L (0, 1) mode waveguide data; it is judged whether the pipeline defect exceeds the detection depth range of the T (0, 2) mode; the wall thickness of the pipeline corrosion defect is inverted by the full waveform inversion method according to the T (0, 2) mode waveguide data. In other words, the method for jointly detecting corrosion defects of pressure pipelines using multiple waveguide modes provided by the present invention can obtain more complete information about the wall thickness of the pipeline through the comprehensive use of different waveguide modes, thereby effectively improving the accuracy and reliability of detection; this method provides a more efficient and accurate technical means for non-destructive testing of pressure pipelines, and is particularly suitable for pipeline health monitoring under complex working conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 A schematic flow chart of a method for jointly detecting corrosion defects in pressure pipelines using multiple guided wave modes provided in an embodiment of the present invention; Figure 2 A schematic diagram of ultrasonic guided wave array data acquisition in a method for jointly detecting corrosion defects in pressure pipelines using multiple guided wave modes provided in an embodiment of the present invention; Figure 3 The guided wave dispersion data obtained by analytical calculation in the method for jointly detecting corrosion defects of pressure pipelines using multiple guided wave modes provided in an embodiment of the present invention; Figure 4This is a two-dimensional expansion diagram of the actual situation of a corrosion defect in a pressure pipe (the color bar on the right is the wall thickness, the thicker the pipe wall, the darker the color); Figure 5 A two-dimensional expansion diagram of the wall thickness of pressure pipeline corrosion defects detected using the L (0, 1) mode (the horizontal axis represents the length direction of the pipeline, the vertical axis represents the circumferential direction of the pipeline, the color bar on the right represents the wall thickness, and the thicker the pipeline wall, the darker the color); Figure 6 This is a two-dimensional expansion diagram of the wall thickness of pressure pipeline corrosion defects detected using the T (0, 2) mode (the horizontal axis represents the length direction of the pipeline, the vertical axis represents the circumferential direction of the pipeline, the color bar on the right represents the wall thickness, and the thicker the pipeline wall, the darker the color). DETAILED DESCRIPTION

[0013] For ease of understanding, the method for jointly detecting corrosion defects of pressure pipelines using multiple guided wave modes provided by an embodiment of the present invention is described in detail below in conjunction with the accompanying drawings of the specification.

[0014] The embodiment of the present invention provides a method for detecting corrosion defects of pressure pipelines by using multiple guided wave modes. Figure 1-Figure 6 As shown, the following steps are included: Step S1, calculating the dispersion data of the ultrasonic guided wave of the pressure pipeline, and determining the center frequency of the transducer according to the dispersion data; Step S2, arranging an ultrasonic transducer ring array on both sides of the pressure pipeline to be tested, and acquiring ultrasonic guided wave data of L (0, 1) mode and T (0, 2) mode pressure pipeline detection; Step S3, preprocessing the array waveform data to obtain detection data that can be used for guided wave imaging; Step S4, inverting the wall thickness of the pipeline corrosion defect using a full waveform inversion method based on the L (0, 1) mode guided wave data; Step S5, judging whether the pipeline defect exceeds the detection depth range of the T (0, 2) mode, if it exceeds the detection range, then the process ends; if it does not exceed the detection range, then proceed to the next step; Step S6: invert the wall thickness of the pipeline corrosion defect using the full waveform inversion method based on the T (0, 2) mode guided wave data.

[0015] Compared with the prior art, the method for jointly detecting corrosion defects of pressure pipelines using multiple guided wave modes described in the embodiment of the present invention has the following advantages: In the method for jointly detecting corrosion defects of pressure pipelines using multiple waveguide modes provided by the embodiment of the present invention, the center frequency of the transducer is determined according to the dispersion data by calculating the dispersion data of ultrasonic waveguide waves of pressure pipelines; an annular array of ultrasonic transducers is arranged on both sides of the pressure pipeline to be tested to obtain ultrasonic waveguide wave data of pressure pipeline detection in L (0, 1) mode and T (0, 2) mode; the array waveform data is preprocessed to obtain detection data that can be used for guided wave imaging; the wall thickness of the pipeline corrosion defect is inverted by the full waveform inversion method according to the L (0, 1) mode waveguide data; it is judged whether the pipeline defect exceeds the detection depth range of the T (0, 2) mode; the wall thickness of the pipeline corrosion defect is inverted by the full waveform inversion method according to the T (0, 2) mode waveguide data. In other words, the method for jointly detecting corrosion defects of pressure pipelines using multiple waveguide modes provided by the embodiment of the present invention can obtain more complete information about the wall thickness of the pipeline through the comprehensive use of different waveguide modes, thereby effectively improving the accuracy and reliability of detection; this method provides a more efficient and accurate technical means for non-destructive testing of pressure pipelines, and is particularly suitable for pipeline health monitoring under complex working conditions.

[0016] In practical application, the above step S1 may specifically include the following steps: Step S11: Through theoretical analysis of the ultrasonic propagation characteristics of the pressure pipeline, the dispersion equations of ultrasonic Lamb waves of different mode waves can be obtained: ; in, represents the angular frequency, is the wave number of the ultrasonic Lamb wave, is the thickness of the pressure pipe, Represents the elastic parameters of the pressure pipe; the dispersion data of different mode waves can be obtained by solving the dispersion equation; Step S12: Solve the dispersion equation using the dichotomy method to obtain phase velocity dispersion data, and use the frequency that changes faster with the phase velocity as the basis for selecting the main frequency of the ultrasonic transducer.

[0017] Specifically, the above step S3 may include the following steps: Step S31, setting the starting point and end point of the time window for selecting a specific waveguide mode according to the dispersion data and the distance between the sound source and the receiver: ; in, Indicates the starting point of the time window. is the distance between the transmitting and receiving transducers, It represents the group velocity of the guided wave at the center frequency of the transmitting transducer and is calculated as follows: , represents the end point of the time window, is the duration of the signal used to excite the transmitting transducer; Step S32: After the start and end points of the time window are determined, the time window function can be designed. , for the original measured signal Multiply to obtain waveform data that can be used for guided wave imaging .

[0018] Furthermore, the above step S5 may specifically include the following steps: Step S51: judging the minimum wall thickness of the pressure pipe that can be detected by the T (0, 2) mode according to the guided wave dispersion data calculated in step S1: ; in, Indicates the minimum wall thickness of the pressure pipe that can be detected by the T (0, 2) mode. is the original thickness of the pressure pipe, represents the cutoff frequency of the T(0,2) mode, represents the cutoff frequency of the T(0,3) mode; Step S52: compare with the minimum pressure pipe wall thickness inverted by L (0, 1) mode, if it satisfies If the condition is met, step S6 is executed; in, Indicates the minimum wall thickness of the pressure pipe for L(0,1) mode inversion.

[0019] The feasibility and application effect of the method for jointly detecting corrosion defects of pressure pipelines using multiple guided wave modes provided by the embodiment of the present invention are further explained with the help of the accompanying drawings: First, use Figure 2 The array data acquisition scheme shown in the figure obtained the array waveform data, and the phase velocity dispersion curve of the aluminum tube with an outer diameter of 100 mm and a wall thickness of 10 mm was obtained based on the analytical calculation method (see Figure 2 As shown in the figure, the phase velocity dispersion curve shows that the L(0,1) mode, as an asymmetric mode, is easier to excite than the L(0,2) mode. In addition, the excitation of the L(0,3) or higher-order modes will inevitably generate low-order L(0,1) and L(0,2) modes, which brings complexity to the processing of guided wave signals. Therefore, most of the detection based on guided wave is based on the low-order L(0,1) mode for detection. From the dispersion curve, the L(0,1) mode has a strong phase velocity dispersion characteristic at about 50kHz, indicating that the L(0,1) mode is sensitive to thickness in this frequency range. Therefore, the 50kHz L(0,1) mode is first used to detect the defective pipe (e.g. Figure 4 As shown in the figure, the black area is the healthy area without defects, and the white area is the defective area). Figure 5The two-dimensional expansion diagram of the pressure pipe wall thickness shown in the figure shows that the detection accuracy of this mode is relatively low compared with the actual wall thickness condition, and the minimum pressure pipe wall thickness that can be detected is about 8mm. Therefore, we try to use the T (0, 2) mode, which has more obvious dispersion characteristics and is more sensitive to the pressure pipe wall thickness, to detect the pressure pipe wall thickness. First, according to the process, the pipe wall thickness detection range of the T (0, 2) mode was calculated; from the phase velocity dispersion curve, it can be seen that the cutoff frequencies of the T (0, 2) and T (0, 3) modes are approximately 160kHz and 320kHz. Therefore, after calculation, for a 10mm thick aluminum pipe, the maximum corrosion depth that can be detected by the T (0, 2) mode is 5mm, and the remaining wall thickness of 8mm (maximum corrosion of 2mm) is within the detection depth range of the T (0, 2) mode. Therefore, the T (0, 2) mode can be used to detect the wall thickness of the pressure pipeline; Finally, we obtained Figure 6 The two-dimensional unfolded diagram of the pressure pipe wall thickness is shown; it can be seen from the figure that the detection accuracy of the pressure pipe wall thickness using the T (0, 2) mode is greater than the detection accuracy of the L (0, 1) mode, indicating the advantage of the method of the present application.

[0020] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A method for detecting corrosion defects in pressure pipelines by using multiple guided wave modes, characterized in that: The following steps are involved: Step S1, calculating the dispersion data of the ultrasonic guided wave of the pressure pipeline, and determining the center frequency of the transducer according to the dispersion data; Step S2, arranging an ultrasonic transducer ring array on both sides of the pressure pipeline to be tested, and acquiring ultrasonic guided wave data of L (0, 1) mode and T (0, 2) mode pressure pipeline detection; Step S3, preprocessing the array waveform data to obtain detection data that can be used for guided wave imaging; Step S4, inverting the wall thickness of the pipeline corrosion defect using a full waveform inversion method based on the L (0, 1) mode guided wave data; Step S5, judging whether the pipeline defect exceeds the detection depth range of the T (0, 2) mode, if it exceeds the detection range, then the process ends; if it does not exceed the detection range, then proceed to the next step; Step S6: invert the wall thickness of the pipeline corrosion defect using the full waveform inversion method based on the T (0, 2) mode guided wave data.

2. The method for detecting corrosion defects of pressure pipelines by using multiple guided wave modes according to claim 1 is characterized in that: The step S1 specifically includes the following steps: Step S11: Through theoretical analysis of the ultrasonic propagation characteristics of the pressure pipeline, the dispersion equations of ultrasonic Lamb waves of different mode waves can be obtained: ; in, represents the angular frequency, is the wave number of the ultrasonic Lamb wave, is the thickness of the pressure pipe, Represents the elastic parameters of the pressure pipe; the dispersion data of different mode waves can be obtained by solving the dispersion equation; Step S12: Solve the dispersion equation using the dichotomy method to obtain phase velocity dispersion data, and use the frequency that changes faster with the phase velocity as the basis for selecting the main frequency of the ultrasonic transducer.

3. The method for detecting corrosion defects of pressure pipelines by using multiple guided wave modes according to claim 2 is characterized in that: The step S3 specifically comprises the following steps: Step S31, setting the starting point and end point of the time window for selecting a specific waveguide mode according to the dispersion data and the distance between the sound source and the receiver: ; in, Indicates the starting point of the time window. is the distance between the transmitting and receiving transducers, It represents the group velocity of the guided wave at the center frequency of the transmitting transducer and is calculated as follows: , represents the end point of the time window, is the duration of the signal used to excite the transmitting transducer; Step S32: After the start and end points of the time window are determined, the time window function can be designed. , for the original measured signal Multiply to obtain waveform data that can be used for guided wave imaging .

4. The method for detecting corrosion defects of pressure pipelines by using multiple guided wave modes according to claim 3 is characterized in that: The step S5 specifically comprises the following steps: Step S51: judging the minimum wall thickness of the pressure pipe that can be detected by the T (0, 2) mode according to the guided wave dispersion data calculated in step S1: ; in, Indicates the minimum wall thickness of the pressure pipe that can be detected by the T (0, 2) mode. is the original thickness of the pressure pipe, represents the cutoff frequency of the T(0,2) mode, represents the cutoff frequency of the T(0,3) mode; Step S52: compare with the minimum pressure pipe wall thickness inverted by L (0, 1) mode, if it satisfies If the condition is met, step S6 is executed; in, Indicates the minimum wall thickness of the pressure pipe for L(0,1) mode inversion.

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