Transverse excitation detector magnetic field gradient compensation method

Abstract

This invention belongs to the field of pipeline internal inspection technology and aims to solve the problems of large errors and low accuracy in the internal inspection of magnetic pipeline defects in existing technologies. Specifically, it involves a magnetic field gradient compensation method for a transverse excitation detector. Based on a selected pipeline segment, artificial defects are created; the pipeline segment is magnetized using a transverse excitation detector; defect signals of pit-like defects, general defects, axial grooves, and axial concave grooves are collected using the probe of the transverse excitation detector and a static experimental platform to obtain signal relationship diagrams of different types of defects and different positions in the pipeline; based on the defect signal diagrams at different positions of the magnetized field, a reverse compensation model is established to correct the non-uniformity in the transverse magnetization process, and a baseline correction model is obtained; based on the baseline correction model, a sensitivity compensation model is established, and a compensation coefficient is used to correct the sensitivity difference, resulting in a sensitivity compensation model. This invention can effectively reduce the influence of the spatial location of defects on the leakage magnetic field and improve the accuracy of defect quantification.

Description

Technical Field

[0001] This invention belongs to the field of pipeline internal detection technology, specifically relating to a magnetic field gradient compensation method for a transverse excitation detector. Background Technology

[0002] Transverse magnetization, also known as circumferential (or annular) magnetization, generates magnetic field lines that are perpendicular to the direction of axial cracks in the pipe and distributed along the circumference of the pipe. This magnetization can detect crack defects perpendicular to the magnetization direction, i.e., axial cracks that are essentially parallel to the axis.

[0003] However, the actual distribution of the transverse magnetization field is characterized by a maximum magnetic field strength near the poles and a minimum strength at the center of the two poles. This is mainly due to the non-uniform magnetization properties of the pipe material in the transverse direction, which makes the detection and quantification of axial defects more difficult. Defects of the same size but different locations will produce detection signals of varying intensities. Thus, the magnitude of the transverse magnetization detection signal depends not only on the geometry of the defect but also on the position of the magnetic poles, making accurate quantification of defect size difficult and adversely affecting subsequent pipeline operation and maintenance. Summary of the Invention

[0004] To address the aforementioned problems in the prior art, namely the large errors and low accuracy in the detection of defects in magnetic pipes, this invention provides a magnetic field gradient compensation method for a transverse excitation detector. The method includes the following steps: Step S100, based on the selected pipe segment, creating artificial defects; the artificial defects include pit-shaped defects, general defects, axial grooves, and axial recesses.

[0005] Step S200: Magnetize the pipe section using a transverse excitation detector;

[0006] Step S300: The defect signals of the pit-shaped defect, the general defect, the axial groove, and the axial concave groove are collected through the probe of the transverse excitation detector and the static experimental platform to obtain the signal relationship diagram of different types of defects and different positions of the pipeline, that is, the defect signal diagram of different positions of the magnetization field.

[0007] Step S400: Based on the defect signal map at different positions of the magnetization field, establish a reverse compensation model to correct the non-uniformity in the transverse magnetization process and obtain a baseline correction model.

[0008] The reverse compensation model is: y' = -0.049x 2 +8.88x-200; where y' is the output of the baseline compensation model, and x is the angle of the corresponding defect on the pipe circumference;

[0009] Step S500: Based on the baseline correction model, establish a sensitivity compensation model, and use compensation coefficients to correct the sensitivity difference to obtain the sensitivity compensation model.

[0010] The sensitivity compensation model is: a = -0.000148x 2 +0.027x+0.1; where a is the sensitivity compensation coefficient.

[0011] In some preferred embodiments, the pit-like defect has a length of a1, a width of b1, and a depth of h1, where a1 ∈ [10mm, 20mm], b1 ∈ [10mm, 20mm], and h1 ∈ [10%wt, 30%wt].

[0012] The general defect has a length of a2, a width of b2, and a depth of h2, where a2 ∈ [30mm, 40mm], b2 ∈ [30mm, 40mm], and h2 ∈ [10%wt, 30%wt].

[0013] The axial groove has a length of a3, a width of b3, and a depth of h3, where a3 ∈ [20mm, 40mm], b3 ∈ [4mm, 5mm], and h3 ∈ [10% wt, 30% wt].

[0014] The axial groove has a length of a4, a width of b4, and a depth of h4, where a4 ∈ [40mm, 80mm], b4 ∈ [10mm, 20mm], and h4 ∈ [10%wt, 30%wt]; and wt is the pipe wall thickness.

[0015] In some preferred embodiments, there are six pit-shaped defects, and the dimensions of the six pit-shaped defects are: 10 mm in length, 10 mm in width, and 10% wt in depth;

[0016] Length 10mm, width 10mm, depth 20%wt;

[0017] Length 10mm, width 10mm, depth 30%wt;

[0018] Length 20mm, width 20mm, depth 10%wt;

[0019] Length 20mm, width 20mm, depth 20%wt;

[0020] Length 20mm, width 20mm, depth 30%wt.

[0021] In some preferred embodiments, there are six general defects, and the dimensions of the six general defects are: length 30 mm, width 30 mm, and depth 10% wt.

[0022] Length 30mm, width 30mm, depth 20%wt;

[0023] Length 30mm, width 30mm, depth 30%wt;

[0024] Length 40mm, width 40mm, depth 10%wt;

[0025] Length 40mm, width 40mm, depth 20%wt;

[0026] Length 40mm, width 40mm, depth 30%wt.

[0027] In some preferred embodiments, there are six axial grooves, and the dimensions of the six axial grooves are: length 20mm, width 5mm, and depth 10%wt;

[0028] Length 20mm, width 5mm, depth 20%wt;

[0029] Length 20mm, width 5mm, depth 30%wt;

[0030] Length 40mm, width 5mm, depth 10%wt;

[0031] Length 40mm, width 5mm, depth 20%wt;

[0032] Length 40mm, width 5mm, depth 30%wt.

[0033] In some preferred embodiments, there are six axial grooves, and the dimensions of the six axial grooves are: 40 mm in length, 20 mm in width, and 10% wt in depth.

[0034] Length 40mm, width 20mm, depth 20%wt;

[0035] Length 40mm, width 20mm, depth 30%wt;

[0036] Length 80mm, width 20mm, depth 10%wt;

[0037] Length 80mm, width 20mm, depth 20%wt;

[0038] Length 80mm, width 20mm, depth 30%wt.

[0039] In some preferred embodiments, x∈[45°, 135°].

[0040] In some preferred embodiments, the transverse excitation detector includes a cup, a front cup mounting bracket, a steel brush, a permanent magnet, an iron core, a rear cup mounting plate, a probe assembly, and cup pressure plates. The cups are respectively mounted on the iron core through the front cup mounting bracket and the rear cup mounting plate, and are respectively pressed by the two cup pressure plates.

[0041] The permanent magnet is provided in four groups, and the four groups of permanent magnets are arranged in an array along the circumference of the iron core.

[0042] One end of the steel brush is set in close contact with the permanent magnet, and the other end is set in close contact with the inner wall of the pipe to be tested;

[0043] The probe assembly is installed between two adjacent sets of steel brushes, and four sets of the probe assembly are evenly distributed along the circumference.

[0044] In some preferred embodiments, the baseline correction model = actual magnetization field + y'.

[0045] In some preferred embodiments, the sensitivity compensation model is equal to the actual leakage magnetic field * a.

[0046] The beneficial effects of this invention are as follows:

[0047] The present invention proposes a magnetic field gradient compensation method for a transverse excitation detector, which can effectively solve the problem of non-uniformity of the magnetization field caused by the different distances of each sensor from the magnetic pole during the magnetization process of transverse excitation detection technology. It can effectively reduce the influence of the spatial location of defects on the leakage magnetic field and improve the accuracy of defect quantification. Attached Figure Description

[0048] Other features, objects, and advantages of this application will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0049] Figure 1 This is a flowchart illustrating a specific embodiment of the present invention;

[0050] Figure 2 This is a schematic diagram of the baseline compensation principle in this invention;

[0051] Figure 3 This is the baseline compensation curve in this invention;

[0052] Figure 4 This is a schematic diagram of the baseline compensation process in this invention;

[0053] Figure 5 This is the sensitivity compensation curve in this invention;

[0054] Figure 6 This is a cross-sectional schematic diagram of the transverse excitation detector in this invention;

[0055] Figure 7 This is a schematic diagram of the end of the transverse excitation detector in this invention.

[0056] Explanation of reference numerals in the attached diagram: 1. Leather cup pressure plate; 2. Leather cup; 3. Front leather cup mounting bracket; 4. Steel brush; 5. Permanent magnet; 6. Iron core; 7. Rear leather cup mounting plate; 8. Probe assembly. Detailed Implementation

[0057] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0058] This invention provides a method for compensating the magnetic field gradient of a transverse excitation detector. The method includes the following steps: Step S100, based on the selected pipe section, creating artificial defects; wherein, artificial defects include pit-shaped defects, general defects, axial grooves, and axial recesses.

[0059] Step S200: Magnetize the pipe section using a transverse excitation detector;

[0060] Step S300: Collect defect signals of pit-shaped defects, general defects, axial grooves, and axial recesses through the probe of the transverse excitation detector and the static experimental platform to obtain the signal relationship diagram of different types of defects and different positions of the pipeline, that is, the defect signal diagram of different positions of the magnetization field.

[0061] Step S400: Based on the defect signal maps at different locations in the magnetization field, establish a reverse compensation model to correct the non-uniformity during the transverse magnetization process, and obtain the baseline correction model; the reverse compensation model is: y'=-0.049x 2 +8.88x-200; where y' is the output of the baseline compensation model, and x is the angle of the corresponding defect on the pipe circumference;

[0062] Step S500: Based on the baseline calibration model, establish a sensitivity compensation model, and use a compensation coefficient to correct for sensitivity differences to obtain the sensitivity compensation model; the sensitivity compensation model is: a = -0.000148x 2 +0.027x+0.1; where a is the sensitivity compensation coefficient.

[0063] Lateral excitation detection technology can effectively detect axial cracks; however, the magnetization error caused by the different distances of each sensor from the magnetic pole during magnetization directly affects the detection results. The magnetic field gradient compensation method for lateral excitation detectors proposed in this invention can effectively solve the problem of non-uniformity of the magnetization field caused by the different distances of each sensor from the magnetic pole during the magnetization process of lateral excitation detection technology, effectively reduce the influence of the defect spatial location on the leakage magnetic field, and greatly improve the accuracy of defect quantification.

[0064] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0065] See attached document Figure 1 To be continued Figure 7The present invention provides a method for magnetic field gradient compensation of a transverse excitation detector, the method comprising the following steps: Step S100, based on the selected pipe section, creating artificial defects; wherein, artificial defects include pit-shaped defects, general defects, axial grooves and axial recesses;

[0066] Step S200: Magnetize the pipe section using a transverse excitation detector;

[0067] Step S300: Collect defect signals of pit-shaped defects, general defects, axial grooves, and axial recesses through the probe of the transverse excitation detector and the static experimental platform to obtain the signal relationship diagram of different types of defects and different positions of the pipeline, that is, the defect signal diagram of different positions of the magnetization field.

[0068] Step S400: Based on the defect signal maps at different locations in the magnetization field, establish a reverse compensation model to correct the non-uniformity during the transverse magnetization process, and obtain the baseline correction model; the reverse compensation model is: y'=-0.049x 2 +8.88x-200; where y' is the output of the baseline compensation model, and x is the angle of the corresponding defect on the pipe circumference;

[0069] Step S500: Based on the baseline calibration model, establish a sensitivity compensation model, and use a compensation coefficient to correct for sensitivity differences to obtain the sensitivity compensation model; the sensitivity compensation model is: a = -0.000148x 2 +0.027x+0.1; where a is the sensitivity compensation coefficient.

[0070] Preferably, x∈[45°, 135°].

[0071] Furthermore, the pit-shaped defect has a length of a1, a width of b1, and a depth of h1, where a1∈[10mm,20mm], b1∈[10mm,20mm], and h1∈[10%wt,30%wt].

[0072] The length of a typical defect is a2, the width is b2, and the depth is h2, where a2 ∈ [30mm, 40mm], b2 ∈ [30mm, 40mm], and h2 ∈ [10%wt, 30%wt].

[0073] The axial groove has a length of a3, a width of b3, and a depth of h3, where a3 ∈ [20mm, 40mm], b3 ∈ [4mm, 5mm], and h3 ∈ [10%wt, 30%wt].

[0074] The axial groove has a length of a4, a width of b4, and a depth of h4, where a4 ∈ [40mm, 80mm], b4 ∈ [10mm, 20mm], and h4 ∈ [10%wt, 30%wt]; and wt is the pipe wall thickness.

[0075] Preferably, there are six pit-shaped defects, and the dimensions of the six pit-shaped defects are as follows: 10 mm in length, 10 mm in width, and 10% wt in depth; 10 mm in length, 10 mm in width, and 20% wt in depth; 10 mm in length, 10 mm in width, and 30% wt in depth; 20 mm in length, 20 mm in width, and 10% wt in depth; 20 mm in length, 20 mm in width, and 20% wt in depth; and 20 mm in length, 20 mm in width, and 30% wt in depth.

[0076] Preferably, there are six general defects, and the dimensions of the six general defects are as follows: 30 mm in length, 30 mm in width, and 10% wt in depth; 30 mm in length, 30 mm in width, and 20% wt in depth; 30 mm in length, 30 mm in width, and 30% wt in depth; 40 mm in length, 40 mm in width, and 10% wt in depth; 40 mm in length, 40 mm in width, and 20% wt in depth; and 40 mm in length, 40 mm in width, and 30% wt in depth.

[0077] Preferably, there are six axial grooves, and the dimensions of the six axial grooves are as follows: 20 mm in length, 5 mm in width, and 10% wt in depth; 20 mm in length, 5 mm in width, and 20% wt in depth; 20 mm in length, 5 mm in width, and 30% wt in depth; 40 mm in length, 5 mm in width, and 10% wt in depth; 40 mm in length, 5 mm in width, and 20% wt in depth; and 40 mm in length, 5 mm in width, and 30% wt in depth.

[0078] Preferably, there are six axial grooves, and the dimensions of the six axial grooves are as follows: 40 mm in length, 20 mm in width, and 10% wt in depth; 40 mm in length, 20 mm in width, and 20% wt in depth; 40 mm in length, 20 mm in width, and 30% wt in depth; 80 mm in length, 20 mm in width, and 10% wt in depth; 80 mm in length, 20 mm in width, and 20% wt in depth; and 80 mm in length, 20 mm in width, and 30% wt in depth.

[0079] The transverse excitation detector includes a cup 2, a front cup mounting bracket 3, a steel brush 4, a permanent magnet 5, an iron core 6, a rear cup mounting plate 7, a probe assembly 8, and a cup pressure plate 1. The cups are mounted on the iron core via the front cup mounting bracket and the rear cup mounting plate, and are pressed together by two cup pressure plates. There are four sets of permanent magnets arranged in an array along the circumference of the iron core. One end of the steel brush is placed close to the permanent magnet, and the other end is placed against the inner wall of the pipe to be tested. The probe assembly is installed between two adjacent sets of steel brushes, and four sets of probe assemblies are evenly distributed along the circumference.

[0080] In this embodiment, the baseline correction model = actual magnetization field + y'.

[0081] In this embodiment, the sensitivity compensation model = actual leakage magnetic field * a.

[0082] This invention proposes a novel compensation method for magnetization errors caused by the varying distances of sensors from the magnetic poles during the magnetization process in transverse excitation detection technology. By utilizing a baseline compensation model, the non-uniformity of the magnetization field caused by the relative position of the sensors from the magnetic poles can be effectively overcome, making the leakage magnetic field detected at various points on the circumference independent of the specific location. Furthermore, by using sensitivity coefficient compensation, the peak and valley values ​​of the leakage magnetic signal generated by defects at different pole distances can be corrected, reducing the influence of the spatial location of the defect on the leakage magnetic field and improving the accuracy of defect quantification.

[0083] This invention proposes a magnetic field gradient compensation method for a transverse excitation detector. Through simulation and experiment, it can be seen that the relationship between different applied magnetization field strengths and the magnetic induction intensity in the pipe wall is nonlinear; the magnetic flux leakage caused by the reduced wall thickness at the defect also varies with different magnetic field strengths; the strength of the applied magnetic field mainly depends on the position of the defect on the circumference; the closer to the pole, the higher the strength of the applied magnetic field, and the stronger the corresponding leakage magnetic signal.

[0084] Compensation can be implemented as follows: First, baseline compensation: The distribution of the actual magnetization field is related to its position relative to the poles. Therefore, a reverse compensation model can be established to correct the influence of position on the magnetization field and magnetization result. If the mathematical expression of the baseline compensation model is the inverse expression of the magnetization process, then: Baseline compensation result = Actual magnetization field + Baseline compensation model. In this way, the non-uniform distribution of the magnetization field caused by the relative position of the defect from the magnetic poles can be greatly alleviated. In the absence of defects, the uniformity of the compensation result is greatly improved, meaning the correlation coefficient between the corresponding leakage magnetic field and the magnetization position is close to zero. Second, sensitivity compensation: The main reason for the sensitivity difference is the different strengths of the magnetization field. Therefore, magnetization is stronger near the poles, and smaller defects can produce larger leakage magnetic fields. At the center, due to the relatively weaker magnetization field, the same leakage magnetic field must be produced by a defect with a larger geometric size. Therefore, we correct the sensitivity difference using a compensation coefficient. The compensation coefficient is corrected by multiplication, and the correction formula is: Sensitivity compensation result = Actual leakage magnetic field * Compensation coefficient.

[0085] By utilizing a baseline compensation model, the non-uniformity of the magnetization field caused by the relative position of the magnetic poles can be effectively overcome, making the leakage magnetic field detected at various points along the circumference independent of the specific location. Sensitivity coefficient compensation can correct the peak and valley values ​​of the leakage magnetic field signal generated by defects at different pole distances, reducing the influence of the defect's spatial location on the leakage magnetic field and improving the accuracy of defect quantification. Axial long groove defects that threaten pipeline safety can be detected and repaired in a timely manner, thereby ensuring the safe operation of the pipeline.

[0086] The relationship between different applied magnetization field intensities and the magnetic induction intensity within the pipe wall is non-linear. The amount of magnetic flux leakage caused by the reduced wall thickness at the defect also varies depending on the magnetic field intensity. The strength of the applied magnetic field primarily depends on the defect's location on the circumference. The closer to the pole, the stronger the applied magnetic field, and the stronger the corresponding magnetic flux leakage signal. Transverse magnetization gradient compensation primarily involves adjusting the amplitude to average the magnetization intensity. For defect detection processes located between poles, appropriate compensation is crucial; the level of compensated magnetization intensity directly impacts complex defect detection and analysis procedures.

[0087] The first step is the magnetic circuit structure design. Magnetization is a prerequisite for pipeline inspection. It determines whether the inspected object (pipeline) can generate a sufficient measurable and distinguishable magnetic field signal, and also affects the performance characteristics of the detection signal and the structural characteristics of the detection device. Pipeline magnetization is achieved by a transverse excitation detector.

[0088] The second step involves static and dynamic experimental data analysis. A representative set of artificial defects was designed, and 24 standard defects were fabricated on a steel plate, following the principle of identical shape but varying depth. Signals were acquired on a static experimental platform for different types of defects, and the signals were then analyzed and processed. The transverse excitation detector probe was placed in a non-uniform strong magnetic field, and the signal characteristics acquired by the probe were used to determine the variation in signal differences at different locations.

[0089] The third step is to establish a reverse compensation model to correct the influence of position on the magnetization field and magnetization result. The distribution of the magnetization field is related to its position relative to the poles; therefore, a reverse compensation model can be established to correct the influence of position on the magnetization field and magnetization result.

[0090] The mathematical expression of the baseline compensation model is the inverse expression of the magnetization process, where: baseline compensation result = actual magnetization field + baseline compensation model. In the absence of defects, the uniformity of the compensation result is significantly improved, meaning the correlation coefficient between the corresponding leakage magnetic field and the magnetization position approaches zero.

[0091] Based on simulation calculations and actual measurements, the relationship between statistical angles and compensation values ​​is detailed in Table 1. (Regarding the appendix...) Figure 2 The transverse magnetization process shown can be fitted with an angle and compensation value to establish a compensation model as follows: y'=-0.049x 2 +8.88x-200.

[0092] Further refer to the appendix Figure 4 This compensation model is used to correct the non-uniformity of the transverse magnetization process.

[0093] Table 1 Angles and Compensation Values

[0094]

[0095]

[0096]

[0097]

[0098] The fourth step is to establish a sensitivity compensation model and correct for sensitivity differences using compensation coefficients. Through baseline calibration, in the absence of defects, the leakage magnetic signal at various points in the transverse magnetization is essentially uniform. However, when axial defects exist, the varying distances of the defects from the poles will still cause differences in the peak and valley values ​​of the leakage magnetic signal. In other words, the non-uniformity of the actual transverse magnetization also affects defect quantization. Different quantization results are produced for defects at different locations with the same geometric dimensions; this difference is called sensitivity difference. When performing accurate quantization of axial defects, the non-uniformity during transverse magnetization cannot be ignored. Sensitivity differences introduce significant quantization errors to the defects, and compensation is necessary for practical applications.

[0099] The difference in sensitivity is mainly due to the varying strengths of the magnetizing field. Therefore, magnetization is stronger near the poles, allowing smaller defects to generate larger leakage magnetic fields. Conversely, at the center, where the magnetizing field is relatively weaker, a larger defect is required to produce the same leakage magnetic field. Thus, it is necessary to correct for these sensitivity differences using a compensation coefficient.

[0100] The sensitivity compensation coefficient is corrected by multiplication, and the correction formula is: Sensitivity compensation result = Actual leakage magnetic field * Compensation coefficient.

[0101] For the transverse magnetization process, a sensitivity compensation model (mathematical expression) can be established as: a = -0.000148x 2 +0.027x+0.1.

[0102] Although the invention has been described with reference to preferred embodiments, various modifications can be made thereto and components can be replaced with equivalents without departing from the scope of the invention. In particular, the technical features mentioned in the various embodiments can be combined in any manner, provided there is no structural conflict. The invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

[0103] In the description of this invention, terms such as "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," which indicate direction or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings. These are used merely for ease of description and do not indicate or imply that the device or element must have a specific orientation, or be constructed and operated in a specific orientation; therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0104] Furthermore, it should be noted that, in the description of this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0105] The term "comprising" or any other similar term is intended to cover non-exclusive inclusion, such that a process, article, or apparatus / device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to those processes, articles, or apparatus / devices.

[0106] The technical solution of the present invention has been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the scope of protection of the present invention.

Claims

1. A method for compensating the magnetic field gradient of a transverse excitation detector, characterized in that, The method includes the following steps: Step S100: Based on the selected pipe section, create artificial defects; the artificial defects include pit-shaped defects, general defects, axial grooves, and axial recesses. Step S200: Magnetize the pipe section using a transverse excitation detector; Step S300: The defect signals of the pit-shaped defect, the general defect, the axial groove, and the axial concave groove are collected through the probe of the transverse excitation detector and the static experimental platform to obtain the signal relationship diagram of different types of defects and different positions of the pipeline, that is, the defect signal diagram of different positions of the magnetization field. Step S400: Based on the defect signal maps at different locations of the magnetization field, establish a reverse compensation model to correct the non-uniformity during the transverse magnetization process, and obtain a baseline correction model; the baseline correction model = actual magnetization field + ; The reverse compensation model is as follows: ;in, The output of the baseline compensation model. This corresponds to the angle of the defect on the pipe circumference; Step S500: Based on the baseline correction model, establish a sensitivity compensation model, and use compensation coefficients to correct the sensitivity difference to obtain the sensitivity compensation model. The sensitivity compensation model = actual leakage magnetic field ; in, This is the sensitivity compensation coefficient. ; The transverse excitation detector includes a cup, a front cup mounting bracket, a steel brush, a permanent magnet, an iron core, a rear cup mounting plate, a probe assembly, and cup pressure plates. The cups are respectively mounted on the iron core through the front cup mounting bracket and the rear cup mounting plate, and are respectively pressed by the two cup pressure plates. The permanent magnet is provided in four groups, and the four groups of permanent magnets are arranged in an array along the circumference of the iron core. One end of the steel brush is set in close contact with the permanent magnet, and the other end is set in close contact with the inner wall of the pipe to be tested; The probe assembly is installed between two adjacent sets of steel brushes, and four sets of the probe assembly are evenly distributed along the circumference.

2. The magnetic field gradient compensation method for the transverse excitation detector according to claim 1, characterized in that, The length of the pit-shaped defect is , width is Depth is , , , ; The length of the general defect is , width is Depth is , , , ; The length of the axial groove is , width is Depth is , , , ; The length of the axial groove is , width is Depth is , , , ;in, This refers to the pipe wall thickness.

3. The magnetic field gradient compensation method for the transverse excitation detector according to claim 2, characterized in that, There are six pit-shaped defects, and the dimensions of the six pit-shaped defects are as follows: length ,Width ,depth ; long ,Width ,depth ; long ,Width ,depth ; long ,Width ,depth ; long ,Width ,depth ; long ,Width ,depth .

4. The method for compensating the magnetic field gradient of a transverse excitation detector according to claim 2, characterized in that, There are six general defects, and the dimensions of the six general defects are as follows: length ,Width ,depth ; long ,Width ,depth ; long ,Width ,depth ; long ,Width ,depth ; long ,Width ,depth ; long ,Width ,depth .

5. The method for compensating the magnetic field gradient of a transverse excitation detector according to claim 2, characterized in that, There are six axial grooves, and the dimensions of the six axial grooves are as follows: length ,Width ,depth ; long ,Width ,depth ; long ,Width ,depth ; long ,Width ,depth ; long ,Width ,depth ; long ,Width ,depth .

6. The method for compensating the magnetic field gradient of a transverse excitation detector according to claim 2, characterized in that, There are six axial grooves, and the dimensions of the six axial grooves are as follows: length ,Width ,depth ; long ,Width ,depth ; long ,Width ,depth ; long ,Width ,depth ; long ,Width ,depth ; long ,Width ,depth .

7. The method for compensating the magnetic field gradient of a transverse excitation detector according to claim 1, characterized in that, 。

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