Pipeline defect detection system and method

Abstract

A pipeline defect detection system and method. The pipeline defect detection system comprises: a signal detection device and a smart terminal. The signal detection device is configured to: apply an unsaturated static magnetic field and an alternating electromagnetic field to a pipe wall at a position to be detected of a pipeline, collect a disturbance signal of the pipe wall at said position, and send the disturbance signal to the smart terminal. The smart terminal is configured to: analyze the disturbance signal to determine whether there is a defect in the pipe wall at said position.

Description

Pipeline Defect Detection System and Method

[0001] This application claims priority to Chinese patent application No. 202410851129.7, filed on June 28, 2024, the entire contents of which are incorporated herein by reference. Technical Field

[0002] This disclosure relates to the field of electrical variable measurement technology, and in particular to a pipeline defect detection system and method. Background Technology

[0003] With the continuous development of the oil and gas transportation industry, long-distance buried oil and gas pipelines are increasingly being used for transporting oil and gas products. Pipeline transportation, with its safety, efficiency, energy saving, and environmental friendliness, plays a crucial role in economic development. Summary of the Invention

[0004] In a first aspect, this invention discloses a pipeline defect detection system. The pipeline defect detection system includes a signal detection device and a smart terminal. The signal detection device is used to: apply an unsaturated static magnetic field and an alternating electromagnetic field to the pipe wall at the location to be detected, simultaneously collect disturbance signals from the pipe wall at the location to be detected, and send the disturbance signals to the smart terminal. The smart terminal is used to: analyze the disturbance signals and determine whether a defect exists in the pipe wall at the location to be detected.

[0005] Secondly, this disclosure also provides a pipeline defect detection method. This pipeline defect detection method is implemented through the aforementioned pipeline defect detection system, which includes a signal detection device and a smart terminal. The pipeline defect detection method includes: applying an unsaturated static magnetic field and an alternating electromagnetic field to the pipe wall at the location to be detected using the signal detection device; simultaneously acquiring disturbance signals of the pipe wall at the location to be detected; and sending the disturbance signals to the smart terminal; analyzing the disturbance signals through the smart terminal to determine whether a defect exists in the pipe wall at the location to be detected.

[0006] Thirdly, this disclosure also provides an electronic device including a processor. The processor is coupled to a memory. At least one computer program is stored in the memory. The at least one computer program is loaded and executed by the processor to enable the electronic device to implement the above-described pipeline defect detection method.

[0007] Fourthly, this disclosure also provides a computer-readable storage medium. The computer-readable storage medium stores at least one computer program. The at least one computer program is loaded and executed by a processor to enable the computer to implement the aforementioned pipeline defect detection method. Attached Figure Description

[0008] Other features, objects, and advantages of this disclosure will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings.

[0009] Figure 1 is a schematic diagram of a pipeline defect detection system according to an embodiment of the present disclosure.

[0010] Figure 2 is a schematic diagram of signal detection according to an embodiment of the present disclosure.

[0011] Figure 3 is a schematic diagram of the internal structure of a pipeline defect detection sensing system according to an embodiment of the present disclosure.

[0012] Figure 4 is a schematic diagram showing the distribution of multiple detection probes according to an embodiment of the present disclosure.

[0013] Figure 5 is a schematic diagram of another pipeline defect detection system according to an embodiment of the present disclosure.

[0014] Figure 6 is a schematic diagram of defects detected according to an embodiment of the present disclosure.

[0015] Figure 7 is a schematic flowchart of a pipeline defect detection method according to an embodiment of the present disclosure.

[0016] Figure 8 is a schematic diagram of the structure of an electronic device according to an embodiment of the present disclosure. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of this disclosure clearer, the embodiments of this disclosure will be described in further detail below with reference to the accompanying drawings.

[0018] With the continuous growth of energy demand, more and more high-pressure, large-diameter, and thick-walled pipelines are being used for oil and gas transportation. As pipelines age and are subject to third-party construction, various types of damage are inevitable. Internal pipeline inspection is the primary method for detecting defects in the pipeline structure. It enables the detection and quantification of defects before accidents occur, making it a key approach to preventing pipeline accidents.

[0019] With the application of these thick-walled pipes (over 30mm), traditional magnetic flux leakage (MFL) testing, while capable of quickly and reliably detecting localized corrosion in pipes and plates, has a detection limit of 28mm. Beyond 28mm, MFL testing struggles to detect external surface defects and cannot distinguish between internal and external surface defects. Electromagnetic eddy current (EMC) testing can only detect defects 3-4mm deep from the internal surface, limiting its detection depth and preventing comprehensive inspection of the pipe wall. Ultrasonic testing is only suitable for oil pipelines and cannot be used for gas pipelines. Therefore, timely, effective, and rapid identification of defects in thick-walled pipes and the implementation of corresponding solutions are crucial for preventing safety accidents and ensuring energy security, property safety, sustainable economic development, and the safe and stable operation of oil and gas pipelines.

[0020] To address the aforementioned technical problems, this disclosure provides a defect detection system and method.

[0021] As shown in Figure 1, this embodiment of the present disclosure provides a pipeline defect detection system, which includes a signal detection device and a smart terminal.

[0022] The signal detection device is used to: apply an unsaturated static magnetic field and an alternating electromagnetic field to the pipe wall at the location to be detected, simultaneously acquire disturbance signals of the pipe wall at the location to be detected, and send the disturbance signals to a smart terminal. This disclosure is illustrated using pipeline inspection as an example; however, the technical solution of this disclosure is not limited to the field of pipeline inspection technology.

[0023] For example, the frequency range of the alternating electromagnetic field is a preset frequency range, which can be set according to actual conditions, for example, between 100kHz and 5MHz. This disclosure uses 200kHz to 1200kHz as an example for illustration, but this disclosure is not limited thereto.

[0024] The intelligent terminal is used to analyze disturbance signals to determine whether there are defects in the pipe wall at the location to be detected.

[0025] In some embodiments, the signal detection device in the above technical solution includes a permanent magnet. The permanent magnet is used to apply an unsaturated static magnetic field to the pipe wall at the location to be detected. The permanent magnet is used to magnetize the pipe wall at the location to be detected, so that the magnetic induction intensity inside the pipe wall reaches the level required for detection. Under the action of the permanent magnet, the pipe will form a closed magnetic circuit. Since the magnetic field strength of the permanent magnet is less than the required saturation magnetization intensity of the pipe, the inside of the pipe wall will be unsaturated magnetized, thereby generating an unsaturated static magnetic field. For example, in this disclosure, a static magnetic field with a magnetization intensity of less than 1.6T that has not reached the saturation permeability plateau region is considered as an unsaturated static magnetic field, but this disclosure is not limited to this. In some embodiments, in the above technical solution, the signal detection device also includes an iron core, and the permanent magnet is disposed on the iron core. A closed magnetic circuit is formed between the permanent magnet, the iron core, and the pipe wall at the location to be detected, and an unsaturated static magnetic field is applied to the pipe wall at the location to be detected through the closed magnetic circuit. As shown in Figure 2, the permanent magnet is attached to the iron core and located between the iron core and the pipe wall at the location to be detected. When performing defect detection on the pipe wall at the location to be inspected, an air gap is left between the permanent magnet and the pipe wall at the location to be inspected, with the iron core and the pipe wall at the location to be inspected located on both sides of the permanent magnet. It should be noted that multiple permanent magnets can be used. The permanent magnet is attached to the iron core, and during defect detection, a closed magnetic circuit is formed between the permanent magnet, the iron core, and the pipe wall at the location to be inspected. This makes the magnetic field applied to the magnetized pipe wall at the location to be inspected more concentrated and uniform, as shown in Figure 2.

[0026] It should be noted that because the magnetic field strength of the permanent magnet is less than the required saturation magnetization strength of the pipe (generally above 1.6T), the inside of the pipe wall will be unsaturated magnetized. When the pipe wall thickness exceeds 30mm, even using a permanent magnet with a magnetization strength of 1.6T or higher will not cause the pipe wall to reach saturation. In this disclosure, an unsaturated static magnetic field refers to a static magnetic field that will not cause the pipe wall to reach saturation. By using unsaturated magnetization, the pipe is ensured to operate at a specific operating point, resulting in a better detection signal. When integrating subsequent excitation coils and receiving coils, the size and weight of the signal detection device can be effectively reduced.

[0027] In some embodiments, the signal detection device further includes at least one detection probe, which is provided with an excitation coil and a receiving coil. The excitation coil may be a multi-frequency excitation coil, thereby emitting multiple frequencies, and the receiving coil may be a pair of differential receiving coils, as shown in FIG3.

[0028] The signal detection device applies an alternating electromagnetic field to the pipe wall at the location to be detected by a multi-frequency excitation coil. For example, an alternating electromagnetic field with a frequency of 200kHz to 1200kHz can be excited by the multi-frequency excitation coil.

[0029] The signal detection device acquires the disturbance signal of the pipe wall at the detection location through a pair of differential receiving coils. The pair of differential receiving coils consists of two differential receiving coils. These two differential receiving coils are positioned opposite the multi-frequency excitation coil on both sides of the PCB (Printed Circuit Board). The two differential receiving coils differentially amplify the signals (the feedback signal from the pipe wall at the detection location) and then filter them using a low-frequency filter to obtain the disturbance signal of the pipe wall at the detection location. This disturbance signal is then transmitted to the intelligent terminal via a cable. The two differential receiving coils effectively reduce the impact of probe jitter and bounce during sliding detection on signal detection, thereby improving sensor sensitivity.

[0030] In one implementation, the signals detected by the two differential receiving coils can be differentially amplified using the AD8130 differential amplifier chip.

[0031] As shown in Figure 2, during defect detection, the multi-frequency excitation coil of the detection probe is close to the pipe wall at the location to be detected, and an alternating electromagnetic field is applied to the pipe wall at the location to be detected. The detection probe is located directly above the part of the closed magnetic circuit in the pipe wall at the location to be detected.

[0032] The detection principle of this disclosure differs from magnetic flux leakage detection or eddy current detection. The principle is as follows: an unsaturated static magnetic field is applied to the pipe wall using a permanent magnet. If the pipe wall is defect-free, the magnetic lines of force in the portion of the closed magnetic circuit within the pipe wall at the detection location are uniform. If corrosion or other material defects reduce the cross-section of the pipe wall at a certain location, the magnetic lines of force in the portion of the closed magnetic circuit within the pipe wall at the detection location will concentrate, as shown in Figure 2. This results in higher magnetization and lower permeability. The optimal magnetization is selected around the peak permeability. At this point, the change in permeability is most sensitive; the change in permeability alters the impedance of the differential receiving coil, thereby generating a changing signal, i.e., an interference signal, which is then acquired. In other words, deep defects can be detected based on the eddy current field distortion caused by permeability disturbance, meeting the requirements for detecting defects in thick-walled pipes.

[0033] In some embodiments, the pipeline defect detection system further includes a signal generator and a power amplifier, with the power amplifier connected between the signal generator and the multi-frequency excitation coil. The signal generator generates an alternating current signal. The power amplifier amplifies the signal generated by the signal generator before applying it to the multi-frequency excitation coil, thus obtaining a dynamic magnetic field at different frequencies, i.e., an alternating electromagnetic field, which is more advantageous for detecting defects at different depths.

[0034] In some embodiments, when the number of power amplifiers is at least two, the signal generated by the signal generator is amplified in multiple stages. This disclosure uses two-stage amplification as an example for illustration.

[0035] The preamplifier stage uses an OPA445 power amplifier chip. The amplification factor of the OPA445 chip is selected by adjusting a potentiometer, with a range of 10x. The power amplifier stage uses an OPA541 chip. The amplification factor of the OPA541 chip is fixed at 5x. Therefore, the two-stage amplification provides a selectable amplification factor of 50x.

[0036] In some embodiments, the pipeline defect detection system further includes a differential amplifier circuit and a low-frequency filter. When an alternating electromagnetic field is applied to the pipe wall at the detection location, a pair of differential receiving coils acquire the feedback signal from the pipe wall at the detection location. This signal is then processed sequentially by the differential amplifier circuit and the low-frequency filter to obtain a disturbance signal. The differential amplifier circuit increases the signal amplitude, while the low-frequency filter eliminates some of the high-frequency noise during detection, resulting in a less noisy and easier-to-distinguish interference signal. The interference signal is then transmitted to a smart terminal via a cable.

[0037] The differential amplifier circuit can be the AD8130 chip, which features high common-mode rejection ratio, high input impedance, and low noise. It can convert the two-ended signal output by the differential receiving coil induced by the differential receiving coil into a single-ended signal output.

[0038] In some embodiments, the pipeline defect detection system described above further includes a protective housing. A multi-frequency excitation coil, a pair of differential receiving coils, a differential amplifier chip, a low-frequency filter, a signal generator, and a power amplifier are all located within the protective housing.

[0039] The multi-frequency excitation coil, two differential receiving coils, an OPA445 chip, an OPA541 chip, a signal generator, a differential amplifier chip AD8130, and a low-frequency filter are mounted on the same circuit board to obtain the PCB circuit board of this disclosure. The protective shell is mainly composed of polytetrafluoroethylene (PTFE) and ceramic sheets. After the PCB circuit board is installed, its internal space is potted with resin to facilitate sealing and prevent water, dust, etc. from entering the detection probe. The ceramic sheet is generally located at the bottom of the detection probe to reduce wear and tear on the detection probe during travel.

[0040] In some embodiments, in the above technical solutions, during defect detection, the signal detection device is installed on the pipeline detector, and multiple signal detection devices can be arranged on the pipeline detector to simultaneously detect defects in the pipe wall at multiple locations. The multiple signal detection devices can be arranged in a ring or array, etc. The pipeline detector is an intelligent device driven by the pipeline transport medium (such as oil and gas), which can operate autonomously inside the pipeline. It uses onboard sensors to collect real-time data on pipeline corrosion, cracks, geometric deformation, and other defects, and accurately locates the damaged areas.

[0041] The criteria for judging pipeline defects are as follows: A permanent magnet unsaturates the pipe wall, and the magnetic field lines are evenly distributed inside the pipe. In defect-free locations, the coil receives a smooth signal. When a defect exists in the pipeline, the distribution of the magnetic field lines changes, and some lines may even overflow from the pipe wall. This change in the distribution of the magnetic field lines further affects the excitation signal generated by the excitation coil, causing a sudden change in the magnetic field. The defect and its location are located by analyzing the abrupt change (disturbance signal) received by the receiving coil. The position of the defect within the pipe wall affects the signal phase change; the phases of the signals from external and internal defects change in opposite directions, with a phase difference of 180 degrees. In other words, by comparing the signals at different locations in the pipeline, the disturbance signal is determined, thus determining whether a defect exists at the location to be detected. The disturbance signal is collected at the location of the defect and differs from the signal collected at the location without defects. A long-distance natural gas pipeline is used as an example. The diameter of the long-distance natural gas pipeline is 1219 mm, the maximum wall thickness is 32 mm, the transmission pressure is 10 MPa, and the detection speed is 3 m / s. To perform full-circumference defect detection on the pipe wall, 144 detection probes will be fixedly mounted on the internal pipe detector in an array. All data (including interference signals) will be collected by a high-speed data acquisition center (such as a signal acquisition card), as shown in Figure 4. After the internal detector is activated, it is placed in a launching tube, and the pressure inside the launching tube is increased. By switching the on-site process flow, the internal detector is pushed into the main pipeline by airflow. The internal detector, driven by the airflow, performs detection along the entire pipeline.

[0042] The overall framework of the pipeline defect detection system is shown in Figure 5. It integrates 144 detection probes and a permanent magnet magnetization device onto an internal pipeline detector. When the internal detector operates within the pipeline, the detection probes collect information around the entire circumference of the pipeline. The electronic system within the internal detector generates 144 amplified signals, which are applied to each multi-frequency excitation coil. These coils then apply an alternating electromagnetic field to the pipe wall at the detection location. A power amplifier is connected between the signal generator and the multi-frequency excitation coils. The power amplifier amplifies the signal generated by the signal generator, resulting in an amplified signal, which is then applied to different multi-frequency excitation coils. When an alternating electromagnetic field is applied to the pipe wall at the detection location, a pair of differential receiving coils collect the feedback signal from the pipe wall at that location. This signal is then processed sequentially by a differential amplifier chip and a low-frequency filter to obtain a disturbance signal. This disturbance signal is comprehensively collected by a data acquisition card and stored in a smart terminal (such as a computer). The smart terminal identifies and visualizes the pipeline defect signal (interference signal) through offline uploading and signal recognition.

[0043] Figure 6 shows the detection of a defect on the outer surface of a 32mm thick-walled pipe with a 0.5mm opening, demonstrating the effectiveness of this method for detecting defects inside thick-walled pipes.

[0044] As shown in Figure 7, this embodiment of the present disclosure provides a pipeline defect detection method, which employs any of the above-mentioned pipeline defect detection systems. The defect detection method includes: S1 and S2.

[0045] In step S1, an unsaturated static magnetic field and an alternating electromagnetic field are applied to the pipe wall at the location to be inspected using a signal detection device, while simultaneously acquiring disturbance signals from the pipe wall at that location. This disclosure is illustrated using pipe inspection as an example; however, the technical solution of this disclosure is not limited to the field of pipe inspection technology.

[0046] In S2, the disturbance signal is analyzed to determine whether there is a defect in the pipe wall at the location to be detected.

[0047] As shown in Figure 8, this embodiment of the present disclosure provides an electronic device 300. The electronic device 300 includes a processor 320 coupled to a memory 310. The memory 310 stores at least one computer program 330. The at least one computer program 330 is loaded and executed by the processor 320 to enable the electronic device 300 to implement any of the aforementioned pipeline defect detection methods.

[0048] The electronic device 300 can vary considerably due to differences in configuration or performance, and may include one or more processors 320 (Central Processing Units, CPUs) and one or more memories 310. The one or more memories 310 store at least one computer program 330. This at least one computer program 330 is loaded and executed by the one or more processors 320 to enable the electronic device 300 to implement any of the pipeline defect detection methods provided in the above embodiments. Of course, the electronic device 300 may also have wired or wireless network interfaces, a keyboard, and input / output interfaces for input and output. The electronic device 300 may also include other components for implementing device functions, which will not be elaborated here. The electronic device may be a computer, etc.

[0049] This disclosure provides a computer-readable storage medium (e.g., a non-transitory computer-readable storage medium) (confirmed). The computer-readable storage medium stores at least one computer program, which is loaded and executed by a processor to enable a computer to implement any of the above-described pipeline defect detection methods.

[0050] In some embodiments, the computer-readable storage medium may be: read-only memory (ROM), random access memory (RAM), compact disc read-only memory (CD-ROM), magnetic tape, floppy disk, and optical data storage device, etc.

[0051] In an exemplary embodiment, a computer program product or computer program is also provided, which includes computer instructions. The computer instructions are stored in a computer-readable storage medium. A processor of an electronic device reads the computer instructions from the computer-readable storage medium and executes the computer instructions, causing the electronic device to perform any of the above-described pipeline defect detection methods.

[0052] It should be noted that the terms "first," "second," etc., used in the specification and claims of this disclosure are used to distinguish similar objects and are not intended to limit a specific order or sequence. Where appropriate, the order of use for similar objects may be interchanged so that the embodiments of this disclosure described herein can be implemented in an order other than that shown or described.

[0053] Those skilled in the art will recognize that this disclosure can be implemented as a system, method, or computer program product. Therefore, this disclosure can be implemented as entirely hardware, entirely software (including firmware, resident software, microcode, etc.), or a combination of hardware and software, generally referred to herein as a "circuit," "module," or "system." Furthermore, in some embodiments, this disclosure can also be implemented as a computer program product contained in one or more computer-readable media, which includes computer-readable program code.

[0054] Any combination of one or more computer-readable media may be used. A computer-readable medium can be a computer-readable signal medium or a computer-readable storage medium. A computer-readable storage medium can be, for example, but not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination thereof. Examples of computer-readable storage media (a non-exhaustive list) include: an electrical connection having one or more wires, a portable computer disk, a hard disk, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage device, magnetic storage device, or any suitable combination thereof. In this disclosure, a computer-readable storage medium can be any tangible medium that contains or stores a program that can be used by or in connection with an instruction execution system, apparatus, or device.

[0055] Although embodiments of the present disclosure have been shown and described above, it is to be understood that the above embodiments are exemplary and should not be construed as limiting the present disclosure. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present disclosure.

Claims

1. A pipeline defect detection system, comprising at least one signal detection device and an intelligent terminal; wherein, The at least one signal detection device is used to: apply an unsaturated static magnetic field and an alternating electromagnetic field to the pipe wall at the location to be detected, simultaneously collect disturbance signals of the pipe wall at the location to be detected, and send the disturbance signals to a smart terminal. The intelligent terminal is used to: analyze the disturbance signal and determine whether there is a defect in the pipe wall at the location to be detected.

2. The pipeline defect detection system according to claim 1, wherein, When the intelligent terminal analyzes the disturbance signal to determine whether there is a defect in the pipe wall at the location to be detected, it determines the disturbance signal by comparing the signals at various locations of the pipeline, and then determines whether there is a defect in the pipe wall at the location to be detected. The disturbance signal is collected at the location of the defect in the pipeline, and the disturbance signal is different from the signal collected at the location of the non-defective part of the pipeline.

3. The pipeline defect detection system according to claim 2, wherein, The smart terminal determines whether the defect is located on the inner wall or the outer wall of the pipe based on the phase change of the disturbance signal, wherein the phase change trend of the disturbance signal caused by the defect on the inner wall of the pipe is opposite to the phase change trend of the disturbance signal caused by the defect on the outer wall of the pipe, and the phase difference is 180°.

4. The pipeline defect detection system according to claim 1, wherein, The frequency of the alternating electromagnetic field is between 100 kHz and 5 MHz.

5. The pipeline defect detection system according to any one of claims 1-4, wherein, Each of the at least one signal detection device further includes: at least one detection probe, the at least one detection probe including an excitation coil and a receiving coil, the excitation coil being used to generate the alternating electromagnetic field, and the receiving coil being used to receive the disturbance signal.

6. The pipeline defect detection system according to claim 5, wherein, The excitation coil is a multi-frequency excitation coil, and the receiving coil is a pair of differential receiving coils.

7. The pipeline defect detection system according to claim 6, wherein, Each of the at least one signal detection device includes a permanent magnet, which is used to apply the unsaturated static magnetic field to the pipe wall at the location to be detected, wherein the unsaturated static magnetic field is a static magnetic field that will not magnetize the pipe wall to a saturated state.

8. The pipeline defect detection system according to claim 7, wherein, Each of the at least one signal detection device further includes an iron core; the permanent magnet is disposed on the iron core and located between the iron core and the pipe wall at the location to be detected; a closed magnetic circuit is formed between the permanent magnet, the iron core and the pipe wall at the location to be detected, and the unsaturated static magnetic field is applied to the pipe wall at the location to be detected through the closed magnetic circuit.

9. The pipeline defect detection system according to claim 8 further includes: A signal generator and a power amplifier are provided, wherein the power amplifier is connected between the signal generator and the multi-frequency excitation coil, the signal generator is used to generate an alternating current signal, and the power amplifier is used to amplify the alternating current signal generated by the signal generator before applying it to the multi-frequency excitation coil.

10. The pipeline defect detection system according to claim 8, further comprising: A signal generator and multiple power amplifiers are provided, wherein the multiple power amplifiers are connected between the signal generator and the multi-frequency excitation coil. The signal generator is used to generate an alternating current signal, and the multiple power amplifiers are used to amplify the alternating current signal generated by the signal generator in multiple stages before applying it to the multi-frequency excitation coil.

11. The pipeline defect detection system according to any one of claims 6-10, further comprising: The differential amplifier chip and low-frequency filter are used in the following configuration: when the alternating electromagnetic field is applied to the pipe wall at the location to be detected, the pair of differential receiving coils collect the feedback signal from the pipe wall at the location to be detected, and the feedback signal is processed sequentially by the differential amplifier chip and the low-frequency filter to obtain the disturbance signal.

12. The pipeline defect detection system according to claim 11, further comprising: The protective housing contains the multi-frequency excitation coil, the pair of differential receiving coils, the differential amplifier chip, the low-frequency filter, the signal generator, and the power amplifier.

13. A pipeline defect detection method, implemented through a pipeline defect detection system, wherein, The pipeline defect detection system includes: at least one signal detection device and a smart terminal; The method includes: An unsaturated static magnetic field and an alternating electromagnetic field are applied to the pipe wall at the location to be detected by each of the at least one signal detection device, while disturbance signals of the pipe wall at the location to be detected are collected and sent to the smart terminal. The smart terminal analyzes the disturbance signal to determine whether there is a defect in the pipe wall at the location to be detected.

14. The pipeline defect detection method according to claim 13, wherein, By comparing the signals at various locations of the pipeline through the smart terminal, the disturbance signal is determined, thereby determining whether there is a defect in the pipe wall at the location to be detected. The disturbance signal is collected at the location of the pipeline where there is a defect, and the disturbance signal is different from the signal collected at the location of the pipeline where there is no defect.

15. The pipeline defect detection method according to claim 14, wherein, The intelligent terminal determines whether the defect is located on the inner wall or the outer wall of the pipe based on the phase change of the disturbance signal, wherein the phase change trend of the disturbance signal caused by the defect on the inner wall of the pipe is opposite to the phase change trend of the disturbance signal caused by the defect on the outer wall of the pipe, and the phase difference is 180°.

16. The pipeline defect detection method according to claim 13, wherein, The frequency of the alternating electromagnetic field is between 100 kHz and 5 MHz.

17. The pipeline defect detection method according to claim 13, wherein, In the case of pipeline defect detection, the at least one signal detection device is installed on the detector inside the pipeline.

18. The pipeline defect detection method according to any one of claims 13 to 17, wherein, Each of the at least one signal detection device further includes: at least one detection probe, the at least one detection probe including an excitation coil and a receiving coil, and the method further includes: The alternating electromagnetic field is generated by the excitation coil, and the disturbance signal is received by the receiving coil.

19. The pipeline defect detection method according to claim 18, wherein, The excitation coil is a multi-frequency excitation coil, the receiving coil is a pair of differential receiving coils, and the method further includes: The multi-frequency excitation coil generates alternating electromagnetic fields at different frequencies, and the disturbance signal is received by the pair of differential receiving coils.

20. The pipeline defect detection method according to claim 19, wherein, Each of the at least one signal detection device includes a permanent magnet. The method further includes: The unsaturated static magnetic field is applied to the pipe wall at the location to be detected by the permanent magnet. The unsaturated static magnetic field is a static magnetic field that will not magnetize the pipe wall to a saturated state.

21. The pipeline defect detection method according to claim 19, wherein, Each of the at least one signal detection device further includes an iron core; the permanent magnet is disposed on the iron core and located between the iron core and the pipe wall at the location to be detected; a closed magnetic circuit is formed between the permanent magnet, the iron core, and the pipe wall at the location to be detected. The method further includes: The unsaturated static magnetic field is applied to the pipe wall at the location to be detected through the closed magnetic circuit.

22. The pipeline defect detection method according to claim 21, wherein, The pipeline defect detection system also includes a signal generator and a power amplifier, wherein the power amplifier is connected between the signal generator and the multi-frequency excitation coil. The method further includes: An alternating current signal is generated by the signal generator, and the power amplifier amplifies the alternating current signal generated by the signal generator before applying it to the multi-frequency excitation coil.

23. The pipeline defect detection method according to claim 21, wherein, The pipeline defect detection system further includes a signal generator and multiple power amplifiers, wherein the multiple power amplifiers are connected between the signal generator and the multi-frequency excitation coil. The method further includes: An alternating current signal is generated by the signal generator. After the alternating current signal generated by the signal generator is amplified in multiple stages by the multiple power amplifiers, it is applied to the multi-frequency excitation coil to amplify the alternating current signal generated by the signal generator in multiple stages.

24. The pipeline defect detection method according to any one of claims 19 to 23, wherein, The pipeline defect detection system further includes: a differential amplifier chip and a low-frequency filter; the method further includes: When the alternating electromagnetic field is applied to the pipe wall at the location to be detected, the feedback signal of the pipe wall at the location to be detected is acquired by the pair of differential receiving coils, and the feedback signal is processed by the differential amplifier chip and the low-frequency filter in sequence to obtain the disturbance signal.