A device for detecting cracks in a pipeline under remanence conditions

Abstract

The application discloses a pipeline crack inner detection device under a residual magnetic condition, and applies to the technical field of pipeline nondestructive testing, and comprises: a front magnetic joint and a rear detection joint which are connected in sequence along the pipeline running direction; a magnetization assembly is arranged on the front magnetic joint to magnetize the pipeline through the magnetization assembly, so that a residual magnetic field is left for the rear detection joint to detect; a residual magnetic detection probe is arranged on the rear detection joint, and the residual magnetic detection probe comprises: a magnetic resistance sensing unit, which is used for collecting a residual magnetic signal of a to-be-detected position of the pipeline after magnetization and outputting a voltage signal corresponding to the residual magnetic signal; a transmission unit, which is used for amplifying, buffering and analog-digital converting the voltage signal; and a processing unit, which is used for receiving an output signal of the transmission unit and determining a crack detection result of the to-be-detected position. The pipeline crack inner detection device under the residual magnetic condition can run along the pipeline, meets the use requirement of mobile detection in an actual environment, and guarantees the reliability of the obtained crack detection result.

Description

Technical Field

[0001] This invention relates to the field of non-destructive testing technology for pipelines, and in particular to a device for detecting internal cracks in pipelines under residual magnetic conditions. Background Technology

[0002] Ferromagnetic pipelines, such as oil and gas pipelines, may develop problems such as cracks, stress concentration, and weld defects during long-term use. Current pipeline magnetic flux leakage detection solutions can be found here. Figure 1 Typically, an integrated structure is used to simultaneously magnetize and detect. The magnet section is arranged together with the MFL (Magnetic Flux Leakage) probe. A strong saturation magnetic field is applied through the magnet section, and the leakage magnetic signal of the pipe wall is collected at the same time. Because the amplitude of the basic magnetic field is very high, the magnetic field brought by the crack defect is superimposed on the large-amplitude basic magnetic field, and the signal has a very low relative proportion. The disturbance signal brought by the tiny crack is easily masked (that is, the MFL signal is not significant), resulting in a high rate of missed detection and false detection.

[0003] Furthermore, in some current solutions, the output signal of the magnetic sensor is directly fed into the ADC (Analog-to-Digital Converter) for sampling. Due to the small signal amplitude, large common-mode interference, and mismatch between the output impedance of the pre-amplifier and the sampling and holding capacitance of the ADC, sampling errors and signal fluctuations are easily generated. Therefore, current solutions are mostly used for static detection in laboratory settings and cannot meet the needs of detecting movement inside pipelines in real-world environments. In other words, current solutions do not provide a complete probe structure and corresponding acquisition system for the actual working conditions of pipeline detection.

[0004] In summary, how to achieve internal detection of pipeline cracks, ensure the reliability of detection results, and meet the needs of mobile detection in real-world environments is a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] The purpose of this invention is to provide a device for detecting internal pipe cracks under residual magnetism conditions, so as to realize the detection of internal pipe cracks, ensure the reliability of the detection results, and meet the needs of mobile detection in actual environments.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0007] In a first aspect, the present invention provides a device for detecting internal cracks in a pipeline under residual magnetism conditions, comprising: a front magnetization section and a rear detection section connected sequentially along the pipeline travel direction;

[0008] The front magnetization section is equipped with a magnetization component to magnetize the pipeline, so that the pipeline retains a residual magnetic field during the detection process of the rear detection section.

[0009] A residual magnetism detection probe is arranged on the rear detection section, and the residual magnetism detection probe includes:

[0010] A magnetoresistive sensing unit is used to acquire the residual magnetic signal at the test position after the pipeline is magnetized, and output a voltage signal corresponding to the residual magnetic signal.

[0011] The transmission unit is used to amplify, buffer, and perform analog-to-digital conversion on the voltage signal;

[0012] The processing unit is used to receive the output signal of the transmission unit and determine the crack detection result at the test location based on the output signal.

[0013] In one embodiment, the magnetoresistive sensing unit is a differential magnetoresistive sensing unit to output a differential voltage signal corresponding to the residual magnetization signal, and the sensitivity range of the magnetoresistive sensing unit to the residual magnetization signal covers the range of magnetic induction intensity change in the crack region after the pipeline is magnetized.

[0014] In one embodiment, the transmission unit includes:

[0015] An amplifier circuit for amplifying the voltage signal;

[0016] A buffer circuit connected to the amplifier circuit;

[0017] An analog-to-digital converter circuit connected to the buffer circuit.

[0018] In one embodiment, the amplifier circuit is a differential-to-single-ended amplifier circuit, and the amplifier circuit includes a first operational amplifier, a second operational amplifier, a third operational amplifier, a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, and a seventh resistor.

[0019] The non-inverting input terminal of the first operational amplifier is connected to the positive output terminal of the magnetoresistive sensing unit and the first terminal of the sixth resistor, respectively. The non-inverting input terminal of the second operational amplifier is connected to the negative output terminal of the magnetoresistive sensing unit and the second terminal of the third resistor, respectively. The output terminal of the first operational amplifier is connected to the second terminal of the sixth resistor and the first terminal of the first resistor, respectively. The output terminal of the second operational amplifier is connected to the second terminal of the seventh resistor and the first terminal of the second resistor, respectively. The inverting input terminal of the first operational amplifier is connected to the first terminal of the third resistor, and the inverting input terminal of the second operational amplifier is connected to the first terminal of the seventh resistor.

[0020] The inverting input terminal of the third operational amplifier is connected to the second terminal of the first resistor and the first terminal of the fourth resistor, respectively. The non-inverting input terminal of the third operational amplifier is connected to the second terminal of the second resistor and the first terminal of the fifth resistor, respectively. The second terminal of the fifth resistor is connected to the reference voltage terminal. The output terminal of the third operational amplifier is connected to the second terminal of the fourth resistor, and the connection terminal serves as the output terminal of the amplifier circuit.

[0021] In one embodiment, the buffer circuit includes a fourth operational amplifier;

[0022] The non-inverting input of the fourth operational amplifier is connected to the output of the amplifier circuit, and the output of the fourth operational amplifier is connected to the inverting input of the fourth operational amplifier, with the connection point serving as the output of the buffer circuit.

[0023] In one embodiment, the residual magnetism detection probe further includes:

[0024] The communication unit is used to output the crack detection results at the location to be tested determined by the processing unit.

[0025] In one embodiment, the residual magnetism detection probe further includes a probe housing, and the wall-mounted side of the probe housing is an insulating housing that is non-ferromagnetic and has a hardness higher than a preset hardness threshold.

[0026] In one embodiment, the magnetoresistive sensing unit, the transmission unit, and the processing unit are all arranged on a PCB, which is mounted inside the probe housing and fixed with potting compound.

[0027] In one embodiment, the probe housing is arranged on the probe base of the rear detection section via a probe support arm, and a pre-tightening component is provided on the probe support arm to provide pre-tightening force for the wall-attached side of the probe housing to adhere to the inner wall of the pipe.

[0028] In one embodiment, the rear detection section is provided with a plurality of residual magnetism detection probes arranged along the circumference of the pipe to form a probe array in the circumferential direction.

[0029] The technical solution provided by this invention allows the pipeline crack detection device under residual magnetism conditions to travel along the pipeline, thus meeting the needs of mobile detection in real-world environments. The pipeline crack detection device under residual magnetism conditions includes a front magnetization section and a rear detection section connected sequentially along the pipeline's travel direction. This means that the front magnetization section and the rear detection section have a certain spatial distance, allowing the magnetization and detection processes to be completed in a time-sharing manner rather than synchronously. In other words, the rear detection section detects the residual magnetic field remaining after the pipeline has been magnetized. This detection method effectively improves the detection accuracy of this application. A residual magnetism detection probe is arranged on the rear detection section. The magnetoresistive sensing unit in the residual magnetism detection probe is used to collect the residual magnetism signal at the test location after the pipeline has been magnetized and outputs a voltage signal corresponding to the residual magnetism signal. The transmission unit can amplify, buffer, and perform analog-to-digital conversion on the voltage signal, thereby effectively improving detection accuracy. The processing unit can receive the output signal from the transmission unit and determine the crack detection result at the test location based on the output signal.

[0030] In summary, the pipeline crack detection device under residual magnetism conditions proposed in this application can travel along the pipeline, meeting the needs of mobile detection in actual environments, and ensuring the reliability of the obtained crack detection results. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 This is a schematic diagram of the current integrated structure that combines magnetization and detection simultaneously;

[0033] Figure 2 A schematic diagram of a pipe crack detection device under residual magnetism conditions provided in a specific embodiment of the present invention;

[0034] Figure 3 This is a schematic diagram of the structure of a residual magnetism detection probe in a specific embodiment of the present invention;

[0035] Figure 4 This is a schematic diagram of the amplifier circuit and buffer circuit in a specific embodiment of the present invention;

[0036] Figure 5 This is a schematic diagram of the overall mechanical structure arrangement of the probe in a specific embodiment of the present invention;

[0037] Figure 6This is a schematic diagram illustrating the arrangement of the magnetization components in one specific embodiment of the present invention. Detailed Implementation

[0038] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of this application.

[0039] To enable those skilled in the art to better understand the present invention, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0040] Please refer to Figure 2 , Figure 2 This is a schematic diagram of the structure of a pipeline crack detection device under residual magnetism conditions according to a specific embodiment of the present invention. The pipeline crack detection device under residual magnetism conditions may include: a front magnetization section 10 and a rear detection section 20 connected sequentially along the pipeline travel direction.

[0041] A magnetization component is arranged on the front magnetization section 10 to magnetize the pipeline so that the pipeline retains a residual magnetic field during the detection process of the rear detection section 20.

[0042] A residual magnetism detection probe 201 is arranged on the rear detection section 20. The residual magnetism detection probe 201 includes:

[0043] The magnetoresistive sensing unit 21 is used to acquire the residual magnetic signal at the test position after the pipeline is magnetized, and output a voltage signal corresponding to the residual magnetic signal.

[0044] Transmission unit 22 is used to amplify, buffer, and perform analog-to-digital conversion on voltage signals;

[0045] The processing unit 23 is used to receive the output signal of the transmission unit 22 and determine the crack detection result at the test location based on the output signal.

[0046] Specifically, the pre-magnetizing section 10 in this application is equipped with a magnetizing component, which can magnetize the pipeline. The post-detection section 20 is a certain distance from the pre-magnetizing section 10, so the post-detection section 20 detects the residual magnetic field remaining in the pipeline. The magnetic induction intensity generated by the pipe wall under normal conditions is different from that of a cracked pipe wall, and this application can thus achieve crack detection of the pipe wall.

[0047] Furthermore, it should be noted that the specific form of the magnetization component arranged on the front magnetization section 10 can be set and adjusted according to actual needs, as long as it can meet the magnetization requirements of this application.

[0048] For example, see the following: Figure 6 This is a schematic diagram illustrating the arrangement of the magnetization component in one specific embodiment. In this embodiment, a double-sided symmetrical yoke-type magnetization component is used. The component consists of paired permanent magnet poles on the left and right sides and a central magnetic yoke. The left and right sides are respectively provided with opposing N and S poles. For example... Figure 6 In this example, the upper left side has an N-pole and a S-pole, with the N-pole facing upwards; the lower left side has an N-pole and a S-pole, with the S-pole facing upwards. The upper right side has an N-pole and a S-pole, with the S-pole facing upwards; the lower right side has an N-pole and a S-pole, with the N-pole facing upwards. This magnetization assembly in this embodiment can conveniently and effectively magnetize the single-layer tube wall to saturation.

[0049] The pipeline crack detection device under residual magnetism conditions of this application can travel along the inside of the pipe. For example, a traction component that cooperates with the pipeline crack detection device under residual magnetism conditions can be set to realize the movement control of the pipeline crack detection device under residual magnetism conditions. The pipeline crack detection device under residual magnetism conditions can also move passively, that is, the movement of the pipeline crack detection device under residual magnetism conditions is driven by the flow of liquid inside the pipe. Neither of these methods affects the implementation of the present invention.

[0050] Crack detection is achieved by a residual magnetism detection probe 201 arranged on the rear detection section 20. The residual magnetism detection probe 201 may include a magnetoresistive sensing unit 21, a transmission unit 22, and a processing unit 23.

[0051] The magnetoresistive sensing unit 21 can acquire the residual magnetic signal at the test location after the pipeline is magnetized, and output a voltage signal corresponding to the residual magnetic signal. It should be noted that traditional pipeline crack residual magnetic detection lacks a dedicated high-sensitivity probe, making it difficult to stably capture weak residual magnetic signals on the order of several hundred microteslas. Therefore, the magnetoresistive sensing unit 21 in this application should be selected to effectively capture weak residual magnetic signals.

[0052] For example, in one specific embodiment, a tunnel magnetoresistive (TMR) sensor TMR2901 is used as the core magnetic sensing element, namely as the magnetoresistive sensing unit 21 of this application. This can improve the ability to sense weak remanent magnetization signals and is suitable for abnormal detection of crack remanent magnetization in the range of several hundred μT to ±1000 μT.

[0053] In one specific embodiment of the present invention, the magnetoresistive sensing unit 21 is a differential magnetoresistive sensing unit to output a differential voltage signal corresponding to the residual magnetism signal, and the sensitivity range of the magnetoresistive sensing unit 21 to the residual magnetism signal covers the range of magnetic induction intensity change in the crack region after the pipeline is magnetized.

[0054] This implementation takes into account that the magnetoresistive sensing unit 21 is a differential magnetoresistive sensing unit, which can output a differential voltage signal corresponding to the remanent magnetization signal, which is beneficial for suppressing common-mode interference. Furthermore, this implementation considers that if the sensitivity range of the magnetoresistive sensing unit 21 to the remanent magnetization signal covers the range of magnetic induction intensity changes in the crack region after the pipe is magnetized, it indicates that the magnetoresistive sensing unit 21 has good linear output capability within this range of magnetic induction intensity changes, thereby ensuring the reliability of the detection results of this application.

[0055] For example, the amplitude of the RMFL (Residual Magnetic Flux Leakage) signal corresponding to a pipe crack is usually in the range of ±1000μT. The TMR2901 has good linear output capability in this range and can meet the signal acquisition requirements for residual magnetic crack detection. Therefore, it can be used as the magnetoresistive sensing unit 21 of this application.

[0056] Taking the TMR2901 as an example again, the magnetoresistive sensing unit 21 can typically be a TMR2901 sensor in an SOP8 package. The TMR2901 sensor has a bridge differential output characteristic, which can convert magnetic flux density into a differential voltage signal. The typical magnetic sensitivity of the TMR2901 is 0.25mV / V / μT, that is, with an excitation voltage of 1V, for every 1μT change in magnetic flux density, the differential voltage output by the sensor changes by 0.25mV. The TMR2901 features high sensitivity, low power consumption, and miniaturization, making it suitable for placement in the residual magnetism detection probe 201 inside a pipeline.

[0057] The magnetoresistive sensing unit 21 acquires the residual magnetic signal at the test position after the pipeline is magnetized and converts it into a corresponding voltage signal. This process can be expressed as Vmr = k1 × B. Here, B is the residual magnetic signal acquired by the magnetoresistive sensing unit 21, specifically referring to the magnetic induction intensity. k1 is the magnetoelectric sensitivity coefficient related to the excitation voltage and device characteristics. Vmr is the output voltage of the magnetoresistive sensing unit 21. For example, when using TMR2901 as the magnetoresistive sensing unit 21, Vmr specifically refers to the differential output voltage of TMR2901.

[0058] It should also be noted that when the magnetoresistive sensing unit 21 collects the residual magnetic signal at the test location after the pipe has been magnetized, the specific direction of the residual magnetic signal collected can be set according to actual needs. For example, in practical applications, considering that the residual magnetic disturbance of the pipe axis (i.e., the extension direction of the pipe) caused by the crack is relatively obvious, the installation angle of the magnetoresistive sensing unit 21 can usually be reasonably set so that the magnetoresistive sensing unit 21 specifically detects the residual magnetic signal in the pipe axis. Of course, in other embodiments, other directions can be set as needed, such as the radial direction of the pipe (i.e., the direction perpendicular to the pipe wall).

[0059] The transmission unit 22 can amplify, buffer, and perform analog-to-digital conversion on the voltage signal, enabling the processing unit 23 to perform subsequent analysis and processing. The transmission unit 22 can be implemented in various ways; for example, in one specific embodiment of the present invention, see [reference needed]. Figure 3 This is a schematic diagram of the structure of the residual magnetism detection probe 201. The transmission unit 22 includes:

[0060] An amplifier circuit 221 for amplifying voltage signals; a buffer circuit 222 connected to the amplifier circuit 221; and an analog-to-digital converter circuit 223 connected to the buffer circuit 222.

[0061] The voltage signal amplitude acquired by the magnetoresistive sensing unit 21 is usually small. Direct sampling can easily lead to insufficient resolution and poor anti-interference capability. Therefore, the voltage signal can be amplified by the amplifier circuit 221.

[0062] The specific structure of the amplifier circuit 221 can be configured according to actual needs. For example, in one specific embodiment of the present invention, see [reference needed]. Figure 4 This is a schematic diagram of the amplifier circuit 221 and the buffer circuit 222.

[0063] In this embodiment, the amplifier circuit 221 is a differential-to-single-ended amplifier circuit, and the amplifier circuit 221 includes a first operational amplifier U1, a second operational amplifier U2, a third operational amplifier U3, a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, and a seventh resistor R7.

[0064] The non-inverting input of the first operational amplifier U1 is connected to the positive output of the magnetoresistive sensing unit 21 and the first end of the sixth resistor R6. The non-inverting input of the second operational amplifier U2 is connected to the negative output of the magnetoresistive sensing unit 21 and the second end of the third resistor R3. The output of the first operational amplifier U1 is connected to the second end of the sixth resistor R6 and the first end of the first resistor R1. The output of the second operational amplifier U2 is connected to the second end of the seventh resistor R7 and the first end of the second resistor R2. The inverting input of the first operational amplifier U1 is connected to the first end of the third resistor R3. The inverting input of the second operational amplifier U2 is connected to the first end of the seventh resistor R7.

[0065] The inverting input terminal of the third operational amplifier U3 is connected to the second terminal of the first resistor R1 and the first terminal of the fourth resistor R4, respectively. The non-inverting input terminal of the third operational amplifier U3 is connected to the second terminal of the second resistor R2 and the first terminal of the fifth resistor R5, respectively. The second terminal of the fifth resistor R5 is connected to the reference voltage terminal Vref. The output terminal of the third operational amplifier U3 is connected to the second terminal of the fourth resistor R4, and the connection terminal serves as the output terminal of the amplifier circuit 221.

[0066] This implementation takes into account that the magnetoresistive sensing unit 21 typically outputs a differential voltage signal. Therefore, the amplifier circuit 221 can specifically employ a differential-to-single-ended amplifier circuit to effectively amplify the differential voltage signal output by the magnetoresistive sensing unit 21 and output it via a single-ended circuit. The positive output terminal of the magnetoresistive sensing unit 21 is located at... Figure 4 The negative and positive output terminals of the magnetoresistive sensing unit 21 are denoted as TMR2901_OUT+. Figure 4 The output terminal of amplifier circuit 221 is designated as TMR2901_OUT-. Figure 4 It is denoted as V_OUT_AMP.

[0067] In this embodiment, the amplifier circuit 221 implements a two-stage differential processing structure, which has a high common-mode rejection effect. Furthermore, the first operational amplifier U1 and the second operational amplifier U2 have independent closed-loop feedback, resulting in high circuit stability and significantly improved anti-oscillation capability.

[0068] use Figure 4In amplifier circuit 221, the resistance values ​​of the first resistor R1 and the second resistor R2 need to be equal, the resistance values ​​of the fourth resistor R4 and the fifth resistor R5 need to be equal, and the resistance values ​​of the sixth resistor R6 and the seventh resistor R7 need to be equal. The output of amplifier circuit 221 is V_OUT_AMP = Vref + (R4 / R1) × (V_U2 - V_U1), where Vref refers to the voltage at the reference voltage terminal, for example, set to 1.65V, R4 refers to the resistance value of the fourth resistor R4, R1 refers to the resistance value of the first resistor R1, and V_U2 and V_U1 refer to the output voltages of the second operational amplifier U2 and the first operational amplifier U1, respectively.

[0069] For example, in one specific embodiment of the present invention, the amplifier circuit 221 specifically uses the AD8226 instrumentation amplifier, which has higher integration and can effectively reduce the space occupied by the transmission unit 22. Furthermore, the AD8226 instrumentation amplifier has high input impedance, low noise, and a high common-mode rejection ratio, which can effectively amplify the bridge differential output of the TMR2901 and reduce the influence of common-mode interference on weak magnetic field signals. Of course, in other embodiments, other instrumentation amplifiers with high input impedance, low noise, high common-mode rejection ratio, and suitable for single-supply operation can be selected to implement the amplifier circuit 221 according to actual needs, without affecting the implementation of the present invention.

[0070] Furthermore, it is understood that the amplification factor of the amplifier circuit 221 can be set according to actual needs. For example, in one embodiment, the system uses a 5V power supply to power the relevant circuit devices in the residual magnetism detection probe 201. Under a 5V excitation voltage, the sensitivity of the TMR2901 can be understood as 1.25mV / μT. Therefore, for a magnetic field variation range of ±1000μT, the output voltage range of the TMR2901 can be understood as ±1.25V. Thus, in a specific embodiment, 2.5V can be used as the reference voltage, and the amplification factor of the AD8226 instrumentation amplifier can be set to 2x. In this case, the output voltage of the AD8226 instrumentation amplifier can be 0 to 5V, which conforms to the typical 0-5V sampling range of an ADC.

[0071] Of course, in other specific embodiments, the magnitude of the reference voltage and the amplification factor of the amplifier circuit 221 can be adaptively adjusted based on the type of magnetoresistive sensing unit 21 and amplifier circuit 221 used, as well as the range of analog-to-digital converter circuit 223, as long as the output voltage range of amplifier circuit 221 falls within the sampling range of analog-to-digital converter circuit 223.

[0072] If the output of amplifier circuit 221 is directly connected to analog-to-digital converter circuit 223, since the ADC sampling terminal usually has a sample-and-hold capacitor, it will draw transient current from the preceding circuit at the moment of sampling. Therefore, if the ADC is directly driven by amplifier circuit 221, the sampling voltage may be too low or dynamic fluctuations may occur due to the limitations of output impedance and driving capability.

[0073] In this application, a buffer circuit 222 is also provided between the amplifier circuit 221 and the analog-to-digital conversion circuit 223, for example... Figure 4 In the implementation of the method, the buffer circuit 222 specifically includes a fourth operational amplifier Ubuf;

[0074] The non-inverting input of the fourth operational amplifier Ubuf is connected to the output of the amplifier circuit 221, and the output of the fourth operational amplifier Ubuf is connected to the inverting input of the fourth operational amplifier Ubuf, with the connection point serving as the output of the buffer circuit 222. Figure 4 The buffer circuit 222 has a simple structure and high reliability.

[0075] In another embodiment, the OPA330 can be used as a voltage follower buffer, improving integration. The OPA330 voltage follower buffer effectively isolates the amplifier circuit 221 from the ADC sample-and-hold circuit, thus absorbing the charging current during ADC sampling and preventing low sampling voltage or dynamic fluctuations, thereby improving the sampling accuracy and stability of the analog-to-digital conversion circuit 223. Of course, in other embodiments, other operational amplifiers or buffers with low output impedance, low offset, and the ability to drive the ADC sample-and-hold capacitor can be selected to implement the buffer circuit 222, without affecting the implementation of this invention.

[0076] In practical applications, after completing the connection of all components, power supply, reference voltage, signal input and output and related interfaces of the residual magnetism detection probe 201 on the PCB board, the risk of short circuit can be checked by static impedance test, and the key points such as 1.8V voltage divider node, 2.5V reference voltage and 5V power supply output can be confirmed by power-on dynamic test to see if they meet the original design requirements.

[0077] After receiving the output signal from the transmission unit 22, the processing unit 23 can determine the crack detection result at the test location based on the output signal. In this application, the specific crack detected is the crack in the inner wall of the pipe. When the residual magnetic field detection probe 201 passes through the crack or defect area, the distribution of the residual magnetic field near the crack will change, which will then be reflected in the output signal of the transmission unit 22. Therefore, the crack detection result at the test location can be obtained accordingly.

[0078] For example, in one specific embodiment, the determination method is as follows: when the output signal of the transmission unit 22 is higher than a preset threshold, it can be determined that there is a crack at the currently detected position of the inner wall of the pipe; otherwise, it is determined that there is no crack. Of course, other specific embodiments can be set with other determination methods as needed. For example, the presence of cracks or abnormal areas in the inner wall of the pipe can be determined based on factors such as the current spatial position of the residual magnetism detection probe 201, the signal amplitude and waveform changes of the output signal of the transmission unit 22, etc.

[0079] In one specific embodiment of the present invention, the residual magnetism detection probe 201 may further include:

[0080] The communication unit is used to output the crack detection results at the location to be tested determined by the processing unit 23.

[0081] In this embodiment, the crack detection results at the location to be tested, as determined by the processing unit 23, can be output using a communication unit, for example, via wired or wireless communication. Outputting the crack detection results facilitates data recording, and in some embodiments, it can also trigger other subsequent processes. For example, when a section of a pipeline is continuously found to have cracks, staff can be notified to conduct manual verification, and relevant maintenance measures, such as replacing the pipeline, can be prepared.

[0082] In one specific embodiment of the present invention, the residual magnetism detection probe 201 may further include a probe housing, and the wall-mounted side of the probe housing is an insulating housing that is non-ferromagnetic and has a hardness higher than a preset hardness threshold.

[0083] This embodiment takes into account that the residual magnetism detection probe 201 can be housed within the probe housing, thereby protecting the probe housing. Furthermore, the wall-mounted side of the probe housing is non-ferromagnetic, preventing distortion of the residual magnetism signal at weak cracks. Since this solution allows for mobile detection, the wall-mounted side of the probe housing will rub against the inner wall of the pipe. Therefore, in this embodiment, the wall-mounted side of the probe housing is made of an insulating shell with a hardness exceeding a preset hardness threshold, thus possessing high wear resistance and enabling long-term stable maintenance of the lift-off value (e.g., a 1mm lift-off value in the example below).

[0084] For example, in one specific implementation method, see [reference needed]. Figure 5The probe housing is cuboid, and the wall-mounted side of the housing is specifically encapsulated with a zirconia ceramic sheet, for example, 1 mm thick. This allows for a lift-off value of approximately 1 mm (the lift-off value refers to the distance between the detection surface of the magnetic sensing element and the surface of the tested pipe wall). Zirconia ceramic has high wear resistance and is a non-magnetic material, so it will not cause magnetic interference to the residual magnetism detection results. In other embodiments, the zirconia ceramic sheet can be replaced with other wear-resistant, non-magnetic insulating materials that will not interfere with magnetic field detection, but the stability of the lift-off value should be guaranteed.

[0085] In one specific embodiment of the present invention, the magnetoresistive sensing unit 21, the transmission unit 22 and the processing unit 23 are all arranged on the PCB, and the PCB is installed in the probe housing and fixed with potting glue.

[0086] This implementation method employs a potting structure, which on the one hand can stabilize the PCB and electronic components, preventing loosening during vibration, impact, or movement; on the other hand, it can improve the protection capability of the probe's internal circuitry and reduce the impact of tube wall friction, dust, or other environmental factors on electronic components during the testing process.

[0087] In one specific embodiment of the present invention, the probe housing is arranged on the probe base of the rear detection section 20 via a probe support arm, and a pre-tightening component is provided on the probe support arm to provide pre-tightening force for the wall-attached side of the probe housing to adhere to the inner wall of the pipe.

[0088] The lift-off value affects the detection results, and generally speaking, the smaller the lift-off value, the more accurate the detection. Therefore, the residual magnetism detection probe 201 in this application should be as close as possible to the inner wall of the pipe. In this embodiment, the probe housing is arranged on the probe base of the rear detection section 20 via a probe support arm. This allows the probe housing to move when the rear detection section 20 moves, which in turn moves the residual magnetism detection probe 201. Furthermore, a pre-tightening component, such as a spring, is provided on the probe support arm or related support structure to provide pre-tightening force, ensuring that the detection surface of the probe (i.e., the wall-adhering side of the probe housing) remains stably adhered to the inner wall of the pipe during movement.

[0089] In one specific embodiment of the present invention, a plurality of residual magnetism detection probes 201 are arranged along the circumferential direction of the pipeline in the rear detection section 20 to form a probe array in the circumferential direction.

[0090] The above explanation uses a single residual magnetism detection probe 201 as an example. This implementation method takes further considerations and can be found in [reference needed]. Figure 5Several residual magnetism detection probes 201 can be arranged along the circumference of the pipeline to form a probe array in the circumferential direction, which enables the acquisition of residual magnetism signals in the entire circumferential position of the pipeline, ensuring the comprehensiveness of the acquisition in this application.

[0091] Of course, if only one residual magnetism detection probe 201 is set up, and it is still necessary to collect residual magnetism signals in the circumferential position of the pipeline, one way to achieve this is to add a rotation control structure so that the residual magnetism detection probe 201 can rotate around the rear detection section 20 in the circumferential direction of the inner wall of the pipeline.

[0092] By applying the technical solution provided in this invention, the pipeline crack detection device under residual magnetism conditions can travel along the pipeline, thereby meeting the needs of mobile detection in actual environments. The pipeline crack detection device under residual magnetism conditions includes a front magnetization section 10 and a rear detection section 20 connected sequentially along the pipeline's travel direction. That is, the front magnetization section 10 and the rear detection section 20 have a certain spatial distance, which means that the magnetization and detection processes are completed in a time-sharing manner rather than synchronously. In other words, when the rear detection section 20 detects, it detects the residual magnetic field remaining after the pipeline has been magnetized. This detection method can effectively improve the detection accuracy of the solution in this application. A residual magnetism detection probe 201 is arranged on the rear detection section 20. The magnetoresistive sensing unit 21 in the residual magnetism detection probe 201 is used to collect the residual magnetism signal at the test position after the pipeline is magnetized, and output a voltage signal corresponding to the residual magnetism signal. The transmission unit 22 can amplify, buffer and convert the voltage signal into analog and digital signals, thereby effectively improving the detection accuracy. The processing unit 23 can receive the output signal of the transmission unit 22 and determine the crack detection result at the test position based on the output signal.

[0093] In summary, the pipeline crack detection device under residual magnetism conditions proposed in this application can travel along the pipeline, meeting the needs of mobile detection in actual environments, and ensuring the reliability of the obtained crack detection results.

[0094] It should also be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0095] Those skilled in the art will further recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the components and steps of the various examples have been generally described in terms of functionality in the foregoing description. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this invention.

[0096] This article uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the technical solutions and core ideas of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the present invention.

Claims

1. A device for detecting internal cracks in pipelines under residual magnetism conditions, characterized in that, include: The front magnetization section and the rear detection section are connected sequentially along the pipeline travel direction; The front magnetization section is equipped with a magnetization component to magnetize the pipeline, so that the pipeline retains a residual magnetic field during the detection process of the rear detection section. A residual magnetism detection probe is arranged on the rear detection section, and the residual magnetism detection probe includes: A magnetoresistive sensing unit is used to acquire the residual magnetic signal at the test position after the pipeline is magnetized, and output a voltage signal corresponding to the residual magnetic signal. The transmission unit is used to amplify, buffer, and perform analog-to-digital conversion on the voltage signal; The processing unit is used to receive the output signal of the transmission unit and determine the crack detection result at the test location based on the output signal.

2. The pipe crack detection device under residual magnetism conditions according to claim 1, characterized in that, The magnetoresistive sensing unit is a differential magnetoresistive sensing unit that outputs a differential voltage signal corresponding to the residual magnetism signal, and the sensitivity range of the magnetoresistive sensing unit to the residual magnetism signal covers the range of magnetic induction intensity change in the crack region after the pipeline is magnetized.

3. The pipe crack detection device under residual magnetism conditions according to claim 1, characterized in that, The transmission unit includes: An amplifier circuit for amplifying the voltage signal; A buffer circuit connected to the amplifier circuit; An analog-to-digital converter circuit connected to the buffer circuit.

4. The pipe crack detection device under residual magnetism conditions according to claim 3, characterized in that, The amplifier circuit is a differential-to-single-ended amplifier circuit, and the amplifier circuit includes a first operational amplifier, a second operational amplifier, a third operational amplifier, a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, and a seventh resistor. The non-inverting input terminal of the first operational amplifier is connected to the positive output terminal of the magnetoresistive sensing unit and the first terminal of the sixth resistor, respectively. The non-inverting input terminal of the second operational amplifier is connected to the negative output terminal of the magnetoresistive sensing unit and the second terminal of the third resistor, respectively. The output terminal of the first operational amplifier is connected to the second terminal of the sixth resistor and the first terminal of the first resistor, respectively. The output terminal of the second operational amplifier is connected to the second terminal of the seventh resistor and the first terminal of the second resistor, respectively. The inverting input terminal of the first operational amplifier is connected to the first terminal of the third resistor, and the inverting input terminal of the second operational amplifier is connected to the first terminal of the seventh resistor. The inverting input terminal of the third operational amplifier is connected to the second terminal of the first resistor and the first terminal of the fourth resistor, respectively. The non-inverting input terminal of the third operational amplifier is connected to the second terminal of the second resistor and the first terminal of the fifth resistor, respectively. The second terminal of the fifth resistor is connected to the reference voltage terminal. The output terminal of the third operational amplifier is connected to the second terminal of the fourth resistor, and the connection terminal serves as the output terminal of the amplifier circuit.

5. The pipe crack detection device under residual magnetism conditions according to claim 3, characterized in that, The buffer circuit includes a fourth operational amplifier; The non-inverting input of the fourth operational amplifier is connected to the output of the amplifier circuit, and the output of the fourth operational amplifier is connected to the inverting input of the fourth operational amplifier, with the connection point serving as the output of the buffer circuit.

6. The pipe crack detection device under residual magnetism conditions according to claim 1, characterized in that, The residual magnetism detection probe also includes: The communication unit is used to output the crack detection results at the location to be tested, as determined by the processing unit.

7. The pipe crack detection device under residual magnetism conditions according to claim 1, characterized in that, The residual magnetism detection probe also includes a probe housing, and the wall-mounted side of the probe housing is an insulating housing that is non-ferromagnetic and has a hardness higher than a preset hardness threshold.

8. The pipe crack detection device under residual magnetism conditions according to claim 7, characterized in that, The magnetoresistive sensing unit, the transmission unit, and the processing unit are all arranged on a PCB, which is installed inside the probe housing and fixed with potting compound.

9. The pipe crack detection device under residual magnetism conditions according to claim 7, characterized in that, The probe housing is arranged on the probe base of the rear detection section via a probe support arm, and a pre-tightening component is provided on the probe support arm to provide pre-tightening force for the wall-attached side of the probe housing to adhere to the inner wall of the pipe.

10. The pipe crack detection device under residual magnetism conditions according to any one of claims 1 to 9, characterized in that, The rear detection section has several residual magnetism detection probes arranged along the circumference of the pipeline to form a probe array in the circumferential direction.

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