A microwave in-pipe defect detection system suitable for buried non-metal pipe

Abstract

The application provides a kind of in-pipe microwave defect detection system suitable for buried non-metal pipeline, it relates to nondestructive testing technical field, the system includes: detection carrier, carries microwave transceiver measuring device, microwave probe detection unit and four probe synchronous line scanning detection unit, for in-pipe travel, in-pipe long distance continuous off-line in-pipe microwave defect detection is carried out;Microwave transceiver measuring device is used to generate microwave excitation signal and receive the reflected echo signal caused by in-pipe defect;Microwave probe detection unit is set on the detection carrier by lift-off distance maintaining structure, for keeping the preset lift-off distance with the inner wall of pipeline;Four probe synchronous line scanning detection unit is used to drive microwave probe detection unit to move along the pipeline axial direction with the detection carrier, and point-by-point microwave detection is carried out on the inner wall of pipeline at different axial positions, to identify in-pipe defect.The application realizes long distance, continuous off-line microwave defect detection in the interior of dn200 small pipe diameter non-metal pipeline.

Description

Technical Field

[0001] This invention relates to the field of nondestructive testing technology, and in particular to an internal microwave defect detection system suitable for buried non-metallic pipelines. Background Technology

[0002] Gas pipelines are an important infrastructure of urban gas transmission and distribution systems. However, during long-term operation, due to factors such as construction quality, foundation settlement, external forces, and material aging, geometric damage such as through holes, blind holes, scratches, and local wall thickness changes can easily occur on the inner wall of the pipeline. Moreover, such defects are often not easily detected in the early stages, posing a significant safety risk.

[0003] Currently, non-metallic pipeline defect detection still faces engineering challenges such as "difficulty in detecting and identifying defects on the inner wall of buried pipelines without excavation." Traditional methods such as ultrasound are affected by the acoustic impedance of non-metallic materials, coupling conditions, and spatial constraints within the pipe, making it difficult to reliably and accurately identify small-sized defects in pipe-based applications, especially limiting the ability to identify millimeter-level holes / geometric changes.

[0004] Microwave inspection technology is highly sensitive to abrupt changes in dielectric constant caused by defects such as cracks and holes, and has the potential for non-contact / near-field inspection. However, current microwave inspection of non-metallic pipelines is mostly based on external inspection or requires connection to external microwave transceiver measurement devices via cables, making it difficult for the system to achieve long-distance inspection and engineering deployment inside the pipeline. At the same time, for small-diameter buried non-metallic pipelines, there is still a lack of microwave internal inspection equipment capable of performing stable scanning inspections inside the pipe, which limits the promotion and application of microwave inspection in urban gas pipeline networks.

[0005] Therefore, how to achieve stable detection of small-sized defects within the limited space of small-diameter buried non-metallic pipes, while simultaneously ensuring the miniaturization of the detection system, detection stability, and engineering feasibility, is a problem that urgently needs to be solved. Summary of the Invention

[0006] This invention provides an internal microwave defect detection system for buried non-metallic pipelines, which addresses the shortcomings of existing technologies in non-metallic pipeline internal inspection, such as the difficulty in detecting geometric damage and other defects, the insufficient ability of traditional ultrasonic methods to identify small-sized defects, and the fact that microwave detection often relies on external detection or external equipment, making it difficult to detect defects on the inner wall of small-diameter pipelines. This invention enables long-distance, continuous offline microwave defect detection inside small-diameter non-metallic pipelines, effectively improving the detection capability and reliability of the detection process for defects inside small-sized pipelines.

[0007] This invention provides an internal microwave defect detection system suitable for buried non-metallic pipelines, comprising: The detection carrier is equipped with a microwave transceiver measurement device, a microwave probe detection unit, and a four-probe synchronous line scanning detection unit. It is used to travel inside buried non-metallic pipelines and perform long-distance continuous offline in-pipe microwave defect detection inside the pipeline. A microwave transceiver measurement device, which is connected to a microwave probe detection unit via a radio frequency connection structure, is used to generate a microwave excitation signal and receive the reflected echo signal caused by defects in the inner wall of buried non-metallic pipes. A microwave probe detection unit is mounted on a detection carrier via a lift-off distance maintaining structure. This structure is used to maintain a preset lift-off distance between the microwave probe detection unit and the inner wall of the buried non-metallic pipeline during the detection process, and to radiate the microwave excitation signal generated by the microwave transceiver measurement device to the inner wall of the pipeline. The four-probe synchronous line scanning detection unit is used to drive the four microwave probes in the microwave probe detection unit to move axially along the buried non-metallic pipeline with the detection carrier, and to perform point-by-point microwave detection on the inner wall of the pipeline at different axial positions, so as to realize four-channel synchronous sampling and axial line scanning detection to identify defects inside the pipeline.

[0008] According to the present invention, an in-pipe microwave defect detection system suitable for buried non-metallic pipelines is provided. The microwave probe detection unit includes a microwave probe and a probe mounting carrier, and the probe mounting carrier is provided with a lift-off distance maintenance structure. The microwave probe is used to transmit microwave excitation signals to the inner wall of the buried non-metallic pipeline and to receive reflected echo signals caused by defects in the inner wall of the buried non-metallic pipeline. The probe mounting carrier is fixedly connected to the microwave probe and is used to set the microwave probe on the detection carrier, ensuring the fixed posture of the microwave probe during the detection process and ensuring that the microwave probe maintains a preset lifting distance from the inner wall of the buried non-metallic pipeline during the detection process.

[0009] According to the present invention, an in-pipe microwave defect detection system suitable for buried non-metallic pipelines is provided. The microwave probe is a waveguide antenna structure, and the open end of the microwave probe is arranged facing the inner wall of the pipeline to enhance the near-field coupling capability between the microwave signal and the pipeline material.

[0010] According to the present invention, a microwave defect detection system for buried non-metallic pipelines is provided. The microwave transceiver measurement device includes a microwave signal source, a receiver, and a signal separation device. The microwave signal source, the receiver, and the signal separation device are integrated into a single-chip microwave transceiver module. The operating frequency band and matching parameters of the single-chip microwave transceiver module are determined based on the test and optimization of non-metallic pipeline defect detection using an experimental platform. The experimental platform is constructed using discrete radio frequency devices and waveguide components.

[0011] According to the present invention, an in-pipe microwave defect detection system suitable for buried non-metallic pipelines is provided. The microwave transceiver measurement device is suitable for installation and operation under the limited space conditions inside buried non-metallic pipelines.

[0012] According to the present invention, an internal microwave defect detection system for buried non-metallic pipelines is provided, wherein the detection carrier is provided with a data storage unit; the microwave transceiver measurement device is further used for: After receiving the reflected echo signal caused by the defect in the inner wall of the buried non-metallic pipeline, the reflection parameter data corresponding to the reflected echo signal is extracted. The reflection parameter data is associated with the corresponding axial position information and recorded to obtain a detection data sequence distributed along the pipeline axis, and the detection data sequence is stored in the data storage unit.

[0013] According to the present invention, an internal microwave defect detection system for buried non-metallic pipelines is provided, the system further comprising: The host computer is used to connect to the detection carrier via a wired interface after the detection carrier has completed the preset detection mileage, export the detection data sequence from the data storage unit of the detection carrier, analyze and process the detection data sequence, and identify defects in the inner wall of buried non-metallic pipelines based on the changes in reflection parameters at different axial positions.

[0014] According to the present invention, an internal microwave defect detection system for buried non-metallic pipelines is provided. The structural dimensions of the detection carrier are adapted to non-metallic pipelines with a diameter of DN200, which is used to achieve stable operation of the internal microwave defect detection system for buried non-metallic pipelines under small diameter conditions.

[0015] According to the present invention, an in-pipe microwave defect detection system suitable for buried non-metallic pipelines is provided. The four-probe synchronous line scanning detection unit includes an in-pipe traveling mechanism for driving the microwave probe to move continuously along the pipeline axis.

[0016] According to the present invention, an internal microwave defect detection system for buried non-metallic pipelines is provided, which is applicable to buried non-metallic pipelines with different types of defects and diameters of DN200.

[0017] This invention provides an in-pipe microwave defect detection system for buried non-metallic pipelines. The system integrates a microwave transceiver measurement device, a microwave probe detection unit, and a four-probe synchronous line scanning detection unit on a detection carrier. This allows for continuous, stable, long-distance offline detection within the pipeline, eliminating the limitations imposed by external measurement equipment. This makes it suitable for the inspection needs of non-metallic pipelines. By employing a lift-off distance maintenance structure to mount the microwave probe detection unit on the detection carrier, the system can operate stably even in small-diameter (dn200) pipes, maintaining microwave detection performance within the limited space of the pipeline and effectively solving the problem of difficult placement of microwave detection equipment in small-diameter non-metallic pipelines. The use of a four-probe synchronous line scanning detection method reduces system complexity while maintaining detection resolution, minimizes cable interference and signal attenuation during the system's movement within the pipe, and improves the reliability and engineering applicability of long-distance in-pipe microwave defect detection. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in this 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 some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0019] Figure 1 This is one of the structural schematic diagrams of an in-pipe microwave defect detection system for buried non-metallic pipelines provided in an embodiment of the present invention.

[0020] Figure 2 This is a front view of the microwave probe structure provided in an embodiment of the present invention.

[0021] Figure 3 This is a right view of the microwave probe structure provided in an embodiment of the present invention.

[0022] Figure 4 This is the second schematic diagram of the structure of the microwave defect detection system for buried non-metallic pipelines provided in this embodiment of the invention. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0024] In the description of embodiments of the present invention, the terms "comprising," "including," or any other variations thereof are intended to cover a 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. Those skilled in the art will understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0025] It should be noted that when an element is referred to as being "set on" another element, it can be directly on the other element or may be interspersed with another element. When an element is considered to be "connected to" another element, it can be directly connected to the other element or may be interspersed with another element. The terms "vertical," "horizontal," "front," "rear," and similar expressions used in the embodiments of the present invention are for illustrative purposes only and do not represent the only possible implementations.

[0026] Unless otherwise defined, all technical and scientific terms used in the embodiments of this invention have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used in this specification in the embodiments of this invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used in the embodiments of this invention includes any combination of one or more of the associated listed items.

[0027] Figure 1 This is one of the structural schematic diagrams of an internal microwave defect detection system for buried non-metallic pipelines provided in an embodiment of the present invention. (Refer to...) Figure 1 This invention provides an internal microwave defect detection system for buried non-metallic pipelines, comprising: The detection carrier 110 is equipped with a microwave transceiver measurement device, a microwave probe detection unit, and a four-probe synchronous line scanning detection unit. It is used to travel inside a buried non-metallic pipeline and perform long-distance continuous offline in-pipe microwave defect detection inside the pipeline. A microwave transceiver measurement device 120 is connected to a microwave probe detection unit via a radio frequency connection structure. It is used to generate microwave excitation signals and receive reflected echo signals caused by defects in the inner wall of buried non-metallic pipes. The microwave probe detection unit 130 is mounted on the detection carrier via a lift-off distance maintaining structure. This structure is used to maintain a preset lift-off distance between the microwave probe detection unit and the inner wall of the buried non-metallic pipeline during the detection process, and to radiate the microwave excitation signal generated by the microwave transceiver measurement device to the inner wall of the pipeline. The four-probe synchronous line scanning detection unit 140 is used to drive the four microwave probes in the microwave probe detection unit to move axially along the buried non-metallic pipeline with the detection carrier, and to perform point-by-point microwave detection on the inner wall of the pipeline at different axial positions, so as to realize four-channel synchronous sampling and axial line scanning detection to identify defects inside the pipeline.

[0028] Buried non-metallic pipelines refer to pipelines laid underground for transporting gases, liquids, or other media. Their pipe bodies can be made of non-metallic materials such as polyethylene (PE), polyvinyl chloride (PVC), and fiberglass reinforced plastic (FRP). Because non-metallic materials do not provide electromagnetic shielding for microwaves, microwave signals can penetrate the pipe wall and interact with the internal medium and pipe wall defects, making them suitable for microwave detection technology.

[0029] Microwave defect detection refers to a method of non-destructive testing of an object using electromagnetic waves (microwaves) typically in the frequency range of 300MHz to 300GHz. When microwaves encounter an interface where the dielectric constant changes abruptly (e.g., the location of a defect in the inner wall of a pipe), a reflected echo signal is generated. In embodiments of the present invention, the location and nature of microwave defects inside the pipe can be inferred by analyzing the amplitude and phase changes of the reflected signal.

[0030] In this embodiment of the invention, the detection carrier 110 can be an in-pipe inspection robot, used to carry a microwave transceiver measurement device 120, a microwave probe detection unit 130, and a four-probe synchronous line scanning detection unit 140, and to move inside the buried non-metallic pipeline, performing point-by-point sampling at a preset step interval. The internal space of the detection carrier can be used to install the microwave transceiver measurement device, and the front end of the detection carrier can be used to arrange the microwave probe and face the inner wall of the buried non-metallic pipeline. The overall structure can meet the requirements for in-pipe defect detection under DN200 pipe diameter conditions. The detection carrier can have a built-in power supply unit and data storage unit, so that the microwave transceiver measurement device, controller, and data storage unit form an integrated offline working link inside the detection carrier. Therefore, in the process of in-pipe microwave defect detection, there is no need to rely on external equipment and external cables, which meets the engineering application requirements of continuous offline detection.

[0031] Specifically, the detection carrier can be a wheeled crawling robot suitable for DN200 pipe diameter. The axial movement of the detection carrier can be controlled by a built-in controller according to a preset step interval. To achieve precise axial positioning, displacement detection units such as photoelectric encoders can be installed on the detection carrier, which output a sampling trigger pulse for each step interval.

[0032] In some embodiments, the radio frequency (RF) connection structure can refer to a low-loss, highly shielded microwave transmission line used to connect the microwave transceiver measurement device and the microwave probe detection unit, such as a semi-rigid coaxial cable, a flexible coaxial cable, or a microstrip line-waveguide conversion structure. By employing an RF connection structure to connect the microwave transceiver measurement device and the microwave probe detection unit, this embodiment of the invention allows the microwave transceiver measurement device to transmit the microwave excitation signal generated by the microwave transceiver measurement device to the microwave probe detection unit, and to receive the reflected echo signal caused by defects in the inner wall of buried non-metallic pipelines.

[0033] In some embodiments, the lift-off distance maintaining structure refers to a mechanical structure used when the microwave probe detection unit is mounted on a detection carrier, which enables the working surface of the microwave probe to maintain a stable and non-contact preset lift-off distance with the inner wall of the buried non-metallic pipe. During the microwave defect detection process inside the pipe, the microwave probe can maintain a relatively constant distance between itself and the inner wall of the pipe at the preset lift-off distance through the stable lift-off distance maintaining structure, thereby ensuring a stable near-field coupling state between the microwave signal and the pipe material.

[0034] Specifically, the lift-off distance holding structure may include elastic support members, rolling support wheels, or rigid retainers to prevent the microwave probe from directly scraping the inner wall, while ensuring the repeatability and stability of the detection signal.

[0035] In this embodiment of the invention, the four-probe synchronous line scanning detection unit can be realized by the axial movement of the in-pipe inspection robot. During the inspection process, the microwave probe can maintain a fixed circumferential posture and move continuously along the pipe axis with the inspection carrier. It performs point-by-point microwave inspection on the inner wall of the pipe at different axial positions and synchronously collects the microwave reflection signal at the corresponding position and stores it through the storage unit to realize the axial identification of defects in the pipe.

[0036] In some embodiments, the four-probe synchronous line scanning detection unit can refer to a detection unit that uses four microwave probes to move point by point along the axial direction of the pipe and collect reflected signals point by point. By employing four-probe synchronous line scanning, this embodiment of the invention facilitates high spatial resolution detection in small-diameter pipes, while reducing the complexity, power consumption, and cost of the detection system.

[0037] This invention utilizes a detection carrier to mount a microwave transceiver measurement device, a microwave probe detection unit, and a four-probe synchronous line scanning detection unit for microwave defect detection inside buried non-metallic pipelines. This integrated arrangement of the microwave transceiver measurement device, microwave probe detection unit, and four-probe synchronous line scanning detection unit within the pipeline avoids the limitations imposed by external measurement equipment on the detection distance. It enables continuous, stable, long-distance offline detection within the pipeline, suitable for the inspection needs of non-metallic pipelines. By employing a lift-off distance maintenance structure to mount the microwave probe detection unit on the detection carrier, the detection system can operate stably under DN200 small-diameter pipe conditions, maintaining microwave detection performance within the limited space of the pipeline and effectively solving the problem of difficult placement of microwave detection equipment in small-diameter non-metallic pipelines. The use of a four-probe synchronous line scanning detection method reduces system complexity while maintaining detection resolution, minimizes cable interference and signal attenuation during the detection system's movement within the pipeline, and improves the reliability and engineering applicability of long-distance microwave defect detection within pipelines.

[0038] Based on any of the above embodiments, the microwave probe detection unit includes a microwave probe and a probe mounting carrier, wherein the probe mounting carrier is provided with a lift-off distance maintaining structure; the microwave probe is used to emit microwave excitation signals to the inner wall of the buried non-metallic pipeline and receive reflected echo signals caused by defects in the inner wall of the buried non-metallic pipeline; the probe mounting carrier is fixedly connected to the microwave probe and is used to set the microwave probe on the detection carrier, ensuring the fixed posture of the microwave probe during the detection process and ensuring that the microwave probe maintains a preset lift-off distance from the inner wall of the buried non-metallic pipeline during the detection process.

[0039] When a microwave probe approaches the inner wall of a buried non-metallic pipe, the radiation field of the probe electromagnetically couples with the pipe wall material. Due to the difference in dielectric parameters between the pipe wall material and air, the near-field distribution of microwaves and the input impedance of the probe change with local structural variations. Therefore, when there are defects such as holes or cracks in the inner wall of the pipe, the dielectric constant at the defect location changes abruptly, causing a change in the input impedance of the microwave probe, thereby altering the amplitude and phase of the reflected echo. In this embodiment of the invention, defects inside the pipe can be identified by detecting the reflection parameters.

[0040] Near-field microwave detection is extremely sensitive to the distance between the microwave probe and the inner wall of the pipe under test. Even small fluctuations in the lift-off distance can directly alter the coupling capacitance and equivalent impedance, introducing background noise. This invention addresses this by designing a probe mounting carrier that is fixedly connected to the microwave probe. By mounting the microwave probe on the in-pipe detection platform (i.e., the detection carrier), the microwave probe maintains a fixed posture during detection and ensures that it always maintains a preset lift-off distance from the pipe wall. Simultaneously, it prevents the microwave probe from deflecting due to pipe bending or vibration, thereby reducing the impact of lift-off distance fluctuations on the amplitude and phase of the microwave reflected signal.

[0041] This invention relates to a probe mounting carrier that is fixedly connected to a microwave probe, thereby fixing the microwave probe onto a detection carrier (i.e., an in-pipe inspection robot). By limiting the relative distance between the microwave probe and the inner wall of the pipe through the detection carrier, the microwave probe maintains a stable lift-off distance during the detection process, suppresses background noise, and reduces the impact of lift-off distance fluctuations on the amplitude and phase of the microwave reflected signal, thus improving the accuracy of in-pipe defect detection results.

[0042] Based on any of the above embodiments, the microwave probe is a waveguide antenna structure, and the open end of the microwave probe is arranged facing the inner wall of the pipe to enhance the near-field coupling capability between the microwave signal and the pipe material.

[0043] In this embodiment of the invention, the microwave probe can be a near-field microwave probe, specifically a conical waveguide antenna structure with the open end facing the inner wall of the pipe. On the one hand, it can transmit microwave signals to the inner wall of the non-metallic pipe and receive reflected echo signals caused by defects such as holes, cracks and geometric damage. On the other hand, it can enhance the near-field coupling capability between the microwave signal and the pipe material, and improve the detection sensitivity of defects such as holes, cracks and geometric damage.

[0044] Figure 2 This is a front view of the microwave probe structure provided in an embodiment of the present invention. Figure 3 This is a right view of the microwave probe structure provided in an embodiment of the present invention. (Refer to...) Figure 2 and Figure 3 The microwave probe employs a conical waveguide antenna structure, which is an integrated waveguide structure that includes an input end and a radiating opening that gradually expands along the propagation direction. By optimizing the opening size, opening length, and structural proportions, it achieves good impedance matching characteristics, radiation efficiency, and frequency response stability in the target frequency band, thereby meeting the requirements for sensitivity, resolution, and stability during defect detection.

[0045] The inner diameter of the input end can be 5.50 mm, the inner diameter of the radiating opening end can be 13 mm, and the outer diameter of the radiating opening end can be 15 mm; the axial length of the straight tube section at the input end can be 15 mm, and the total axial length of the tapered waveguide antenna can be 30 mm.

[0046] Based on any of the above embodiments, the microwave transceiver measurement device includes a microwave signal source, a receiver, and a signal separation device; the microwave signal source, the receiver, and the signal separation device are integrated into a single-chip microwave transceiver module; the operating frequency band and matching parameters of the single-chip microwave transceiver module are determined after testing and optimization of the experimental platform for detecting defects inside non-metallic pipes; the experimental platform is constructed using discrete radio frequency devices and waveguide components.

[0047] In this embodiment of the invention, a microwave transceiver measurement device is used to generate a microwave excitation signal and receive a reflected echo signal. Specifically, the microwave transceiver measurement device may include a microwave signal source, a receiver, and a signal separation device to achieve probe excitation and parameter extraction. During the principle verification stage, an experimental platform can be constructed using discrete RF devices and waveguide components. The waveguide structure parameters and RF link characteristics are tested and optimized through this platform to determine the suitable operating frequency band and matching parameters for detection inside small-diameter non-metallic pipes. After parameter verification, the aforementioned RF functional units (i.e., the microwave signal source, receiver, and signal separation device) can be integrated into a single-chip microwave transceiver module, forming a highly integrated single-board detection system. This reduces external connection structures, effectively reducing size and power consumption, improving the stability and long-distance operational reliability of the detection system, and forming a stable microwave signal transmission-echo reception link.

[0048] This invention integrates the components of a microwave transceiver measurement device (microwave signal source, receiver, and signal separation device) into a single-chip microwave transceiver module. This reduces the space occupied and assembly complexity caused by multiple discrete components, cables, and metal casings. The resulting more internal space on the detection carrier carrying the microwave transceiver measurement device significantly reduces energy consumption during the detection process, extends continuous operating time under battery power, and meets the requirements for long-distance detection. Furthermore, the single-chip microwave transceiver module has fixed internal interconnect paths and consistent impedance, and the packaging provides electromagnetic shielding. This significantly enhances the robustness of the signal transmission-echo reception link of the detection system under complex environments such as pipeline vibration and humidity changes, improving detection stability.

[0049] Based on any of the above embodiments, the microwave transceiver measurement device is suitable for installation and operation under limited space conditions inside buried non-metallic pipelines.

[0050] In this embodiment of the invention, the microwave transceiver measurement device is connected to the microwave probe through a radio frequency connection structure. It can be used to generate microwave excitation signals and receive reflected echo signals, forming a stable microwave signal transmission-echo reception link, and is suitable for installation and operation under the limited space conditions inside the pipeline.

[0051] In this embodiment of the invention, the microwave transceiver measurement device and the microwave probe are connected via an RF connection structure to transmit radio frequency signals. A microwave signal source inside the microwave transceiver measurement device generates a high-frequency excitation signal, which is sent to the microwave probe via the RF connection structure and radiated onto the inner wall of the pipe. The reflected echo signal is collected by the same probe and then transmitted back to the receiver inside the microwave transceiver measurement device via the RF connection structure. This process constitutes a complete microwave signal transmission-echo reception link.

[0052] In some embodiments, the RF connection structure can be designed to run along the internal contour of the detection carrier to avoid interference with moving mechanisms and power supply lines. By fixing the RF connection structure to the detection carrier housing, it can be ensured that the RF connection structure will not fatigue and break or cause signal interruption when the detection carrier moves or turns, which is beneficial for installation and operation in the limited space conditions inside the pipeline.

[0053] Based on any of the above embodiments, the detection carrier is provided with a data storage unit; the microwave transceiver measurement device is further configured to: after receiving the reflected echo signal caused by the defect in the inner wall of the buried non-metallic pipeline, extract the reflection parameter data corresponding to the reflected echo signal; associate and record the reflection parameter data with the corresponding axial position information to obtain a detection data sequence distributed along the pipeline axis, and store the detection data sequence in the data storage unit.

[0054] Specifically, the microwave transceiver measurement device can provide a continuous or scanning microwave excitation signal to the microwave probe, which then radiates the signal onto the inner wall of the pipe. When defects such as holes, cracks, or geometric damage exist on the inner wall of the pipe, the amplitude and phase of the reflected signal will change due to the change in the local dielectric constant. The microwave transceiver measurement device collects the reflected signal and extracts the corresponding reflection parameter data.

[0055] Specifically, during the axial movement of the detection carrier, the system samples different axial positions point by point according to a preset step interval, and associates and records the collected amplitude and phase data (i.e., reflection parameter data) with the corresponding axial position information. The data can be stored in real time through the storage unit to form a sequence of detection data distributed along the pipeline axis. In offline detection mode, data acquisition, preprocessing, and storage are all completed within the device, eliminating the need for external cables to connect to external equipment during the detection process. After completing the predetermined detection mileage, the detection carrier is removed, and the data is exported to a host computer for processing and analysis via a wired interface, thus achieving a data closed loop for long-distance continuous detection.

[0056] Specifically, the data storage unit can provide non-volatile storage, so that the stored detection data will not be lost even if there is an accidental power outage during the microwave defect detection process inside the tube.

[0057] In this embodiment of the invention, the association and storage of reflection parameter data and axial position information are all completed in the microwave transceiver measurement device and the detection carrier, without the need to transmit data to the outside of the pipeline in real time, so that the detection system can operate independently in the buried pipe environment without signal coverage.

[0058] Based on any of the above embodiments, the system further includes: a host computer, configured to connect to the detection carrier via a wired interface after the detection carrier completes a preset detection mileage, export the detection data sequence from the data storage unit of the detection carrier; analyze and process the detection data sequence, and identify defects in the inner wall of buried non-metallic pipelines based on the changes in reflection parameters at different axial positions.

[0059] In this embodiment of the invention, after completing the predetermined inspection mileage, the inspection carrier can be removed, and the data can be exported to a host computer via a wired interface for processing and analysis, thereby achieving a data closed loop for long-distance continuous inspection. After completing the entire inspection, the host computer can analyze and process the exported inspection data, and by comparing the changes in reflection parameters at different locations, identify defects in the inner wall of the pipeline, thus completing the continuous inspection of internal defects in non-metallic pipelines.

[0060] In this embodiment of the invention, the on-site operator only needs to start the detection, let the detection carrier move to the end point, and take out the detection carrier and export the data file after the detection is completed. There is no need to perform complex data calibration or parameter adjustment on the buried pipe site.

[0061] Based on any of the above embodiments, the structural dimensions of the detection carrier are adapted to non-metallic pipes with a diameter of DN200, so as to achieve stable operation of the in-pipe microwave defect detection system suitable for buried non-metallic pipes under small pipe diameter conditions.

[0062] In this embodiment of the invention, the pipe inspection robot is used to travel inside the pipe and is equipped with a microwave transceiver measurement device and a microwave probe. Its overall structural size is adapted to the DN200 pipe diameter and it can travel stably inside the pipe, thereby achieving long-distance continuous inspection.

[0063] Based on any of the above embodiments, the four-probe synchronous line scanning detection unit includes an in-pipe traveling mechanism for driving the microwave probe to move continuously along the pipe axis.

[0064] In this embodiment of the invention, the four-probe synchronous line scanning detection unit may include: an in-pipe traveling mechanism for driving the microwave probe to move continuously along the pipe axis. During the detection process, the microwave probe maintains a fixed circumferential posture, scans point-by-point along the pipe axis with the detection carrier, and simultaneously acquires microwave reflection signals at different axial positions, thereby enabling the identification of defects in the inner wall of buried non-metallic pipes.

[0065] In some embodiments, the four-probe synchronous line scanning detection unit can be mounted on the detection carrier.

[0066] Based on any of the above embodiments, the in-pipe microwave defect detection system is applicable to buried non-metallic pipelines with a diameter of DN200 and different types of defects.

[0067] DN200 indicates that the nominal diameter of the pipe is 200 millimeters. This pipe diameter falls into the category of small to medium diameter pipes and is commonly found in buried branch and trunk pipelines for urban gas and water supply. The detection carrier and microwave transceiver measurement device provided in this embodiment of the invention are adapted to the overall structural dimensions of DN200 pipe diameter. The structural dimensions of the microwave transceiver measurement device can be adjusted according to different pipe diameters and mounted on the adapter carrier. Therefore, DN200 is used as a typical example of a small-diameter pipe for illustration.

[0068] The microwave defect detection system for buried non-metallic pipelines provided in this invention has a reasonable structural design and complete functions. By coordinating the design of the microwave transceiver measurement device, the near-field microwave probe, the lift-off distance maintenance structure, and the four-probe synchronous line scanning detection method, the microwave detection system can achieve offline stable operation inside the DN200 buried non-metallic pipeline, improve the detection capability of small-sized defects, and has good engineering applicability and promotion value.

[0069] To enable those skilled in the art to better understand the embodiments of the present invention, the embodiments of the present invention will be described below through a specific example.

[0070] To address the challenges of detecting geometric damage and other defects in existing non-metallic gas pipeline inspection methods, such as the difficulty in identifying small-sized defects, the limitations of traditional ultrasonic methods in identifying defects, and the reliance on external inspection or connected equipment for microwave inspection, which is unsuitable for pipelines with diameters of DN200 and below, this invention proposes an in-pipe microwave defect detection system suitable for buried non-metallic pipelines. By integrating the microwave transceiver measurement device with the microwave probe detection unit, the system achieves miniaturization and in-pipe integration. Combining the microwave reflection detection principle based on reflection parameters with the axial scanning method of the in-pipe inspection robot (i.e., the detection carrier), effective detection of pipeline inner wall defects is achieved while ensuring a stable lift-off distance for the microwave probe detection unit. Furthermore, the detection process does not require connection to external pipeline equipment; power supply, data acquisition, data preprocessing, and local storage can be completed within the detection carrier, enabling fully offline operation. This enhances the applicability and reliability under complex pipe sections and long-distance travel conditions.

[0071] Figure 4 This is the second schematic diagram of the internal microwave defect detection system for buried non-metallic pipelines provided in this embodiment of the invention. (Refer to...) Figure 4 This invention provides an internal microwave defect detection system for buried non-metallic pipelines, including a microwave transceiver measurement device, a microwave probe detection unit, and a four-probe synchronous line scanning detection unit.

[0072] Among them, the non-metallic pipe can be a DN200 buried non-metallic pipe to be tested with different types of defects.

[0073] Among them, the pipe inspection robot is used to travel inside the pipe and is equipped with a microwave transceiver measurement device and a microwave probe detection unit. Its overall structural size is adapted to the DN200 pipe diameter, and it can travel stably inside the pipe to achieve long-distance continuous inspection.

[0074] The microwave probe detection unit includes a microwave probe, which is a near-field microwave probe. It preferably adopts a waveguide antenna structure, with the open end facing the inner wall of the pipe. It is used to transmit microwave signals to the inner wall of the non-metallic pipe and receive reflected echoes caused by defects such as holes, cracks and geometric damage.

[0075] The microwave probe is fixedly installed on the pipe inspection robot (i.e., the inspection carrier). The inspection robot limits the change in the relative distance between the microwave probe and the inner wall of the pipe, so that the microwave probe maintains a stable lift-off distance during the inspection process, thereby reducing the impact of lift-off fluctuations on the amplitude and phase of the microwave reflected signal.

[0076] The microwave transceiver measurement device is connected to the microwave probe through an RF connection structure to generate microwave excitation signals and receive reflected echo signals, forming a stable microwave signal transmission-echo reception link. The microwave transceiver measurement device may include a microwave signal source, a receiver, and a signal separation device, and is suitable for installation and operation in confined space conditions inside pipelines.

[0077] The four-probe synchronous line scanning detection unit is achieved through the axial movement of the in-pipe inspection robot. During the inspection process, the microwave probe maintains a fixed circumferential posture and moves continuously along the pipe axis with the inspection carrier. It performs point-by-point microwave inspection on the inner wall of the pipe at different axial positions and simultaneously collects the microwave reflection signal at the corresponding position and stores it through the storage unit to realize the axial identification of defects.

[0078] In the actual testing process, the testing carrier is first inserted into the DN200 non-metallic pressure pipeline to be tested from one end of the pipeline. The in-pipe traveling mechanism is then activated, causing the testing carrier to move forward at a constant speed along the pipeline axis. During the testing process, the microwave probe maintains a relatively constant relative distance between itself and the inner wall of the pipeline by using a lift-off distance maintenance structure, thereby ensuring a stable near-field coupling state between the microwave signal and the pipeline material.

[0079] The microwave transceiver measurement device provides a continuous or scanning microwave excitation signal to the microwave probe, which radiates the signal onto the inner wall of the pipe. When defects such as holes, cracks, or geometric damage exist on the inner wall of the pipe, the amplitude and phase of the reflected signal will change due to the change in the local dielectric constant. The microwave transceiver measurement device acquires the reflected signal and extracts the corresponding reflection parameter data.

[0080] During the axial movement of the detection carrier, the system samples different axial positions point by point according to a preset step interval, and associates and records the amplitude and phase data of the collected reflection parameters with the corresponding axial position information. This data is stored in real time through a storage unit to form a detection data sequence distributed along the pipeline axis. In offline detection mode, data acquisition, preprocessing, and storage are all completed within the device, eliminating the need for external cables to connect to external equipment during the detection process. After completing the predetermined detection mileage, the detection carrier is removed, and the data is exported to a host computer for analysis and processing via a wired interface, thus achieving a data closed loop for long-distance continuous detection.

[0081] After the entire inspection is completed, the stored data is analyzed and processed. By comparing the changes in reflection parameters at different locations, defects in the inner wall of the pipe can be identified, thus completing the continuous inspection of internal defects in non-metallic pipes.

[0082] In summary, the embodiments of the present invention have a reasonable structural design and stable operation, enabling long-distance, continuous offline microwave defect detection inside DN200 small-diameter non-metallic pipes. This effectively improves the detection capability of small-sized defects and the reliability of the detection process, and has good engineering applicability and promotional value.

[0083] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A microwave defect detection system for buried non-metallic pipelines, characterized in that, include: The detection carrier is equipped with a microwave transceiver measurement device, a microwave probe detection unit, and a four-probe synchronous line scanning detection unit. It is used to travel inside buried non-metallic pipelines and perform long-distance continuous offline in-pipe microwave defect detection inside the pipeline. A microwave transceiver measurement device, which is connected to a microwave probe detection unit via a radio frequency connection structure, is used to generate a microwave excitation signal and receive the reflected echo signal caused by defects in the inner wall of buried non-metallic pipes. A microwave probe detection unit is mounted on a detection carrier via a lift-off distance maintaining structure. This structure is used to maintain a preset lift-off distance between the microwave probe detection unit and the inner wall of the buried non-metallic pipeline during the detection process, and to radiate the microwave excitation signal generated by the microwave transceiver measurement device to the inner wall of the pipeline. The four-probe synchronous line scanning detection unit is used to drive the four microwave probes in the microwave probe detection unit to move axially along the buried non-metallic pipeline with the detection carrier, and to perform point-by-point microwave detection on the inner wall of the pipeline at different axial positions, so as to realize four-channel synchronous sampling and axial line scanning detection to identify defects inside the pipeline.

2. The microwave defect detection system for buried non-metallic pipelines according to claim 1, characterized in that, The microwave probe detection unit includes a microwave probe and a probe mounting carrier, and the probe mounting carrier is provided with a lift-off distance maintenance structure. The microwave probe is used to transmit microwave excitation signals to the inner wall of the buried non-metallic pipeline and to receive reflected echo signals caused by defects in the inner wall of the buried non-metallic pipeline. The probe mounting carrier is fixedly connected to the microwave probe and is used to set the microwave probe on the detection carrier, ensuring the fixed posture of the microwave probe during the detection process and ensuring that the microwave probe maintains a preset lifting distance from the inner wall of the buried non-metallic pipeline during the detection process.

3. The microwave defect detection system for buried non-metallic pipelines according to claim 2, characterized in that, The microwave probe is a waveguide antenna structure, with its open end facing the inner wall of the pipe to enhance the near-field coupling capability between the microwave signal and the pipe material.

4. The microwave defect detection system for buried non-metallic pipelines according to claim 1, characterized in that, The microwave transceiver measurement device includes a microwave signal source, a receiver, and a signal separation device; the microwave signal source, the receiver, and the signal separation device are integrated into a single-chip microwave transceiver module; the operating frequency band and matching parameters of the single-chip microwave transceiver module are determined based on the test optimization of the experimental platform for detecting defects in non-metallic pipes; the experimental platform is constructed using discrete radio frequency devices and waveguide components.

5. The microwave defect detection system for buried non-metallic pipelines according to claim 1, characterized in that, The microwave transceiver measurement device is suitable for installation and operation in confined space conditions inside buried non-metallic pipelines.

6. The microwave defect detection system for buried non-metallic pipelines according to claim 1, characterized in that, The detection carrier is equipped with a data storage unit; the microwave transceiver measurement device is also used for: After receiving the reflected echo signal caused by the defect in the inner wall of the buried non-metallic pipeline, the reflection parameter data corresponding to the reflected echo signal is extracted. The reflection parameter data is associated with the corresponding axial position information and recorded to obtain a detection data sequence distributed along the pipeline axis, and the detection data sequence is stored in the data storage unit.

7. The microwave defect detection system for buried non-metallic pipelines according to claim 6, characterized in that, The system also includes: The host computer is used to connect to the detection carrier via a wired interface after the detection carrier has completed the preset detection mileage, export the detection data sequence from the data storage unit of the detection carrier, analyze and process the detection data sequence, and identify defects in the inner wall of buried non-metallic pipelines based on the changes in reflection parameters at different axial positions.

8. The microwave defect detection system for buried non-metallic pipelines according to claim 1, characterized in that, The structural dimensions of the detection carrier are adapted to non-metallic pipes with a diameter of DN200, enabling stable operation of the in-pipe microwave defect detection system suitable for buried non-metallic pipes under small pipe diameter conditions.

9. The microwave defect detection system for buried non-metallic pipelines according to claim 1, characterized in that, The four-probe synchronous line scanning detection unit includes an in-pipe traveling mechanism for driving the microwave probe to move continuously along the pipe axis.

10. The microwave defect detection system for buried non-metallic pipelines according to claim 1, characterized in that, The in-pipe microwave defect detection system is applicable to buried non-metallic pipelines with different types of defects in diameter DN200.

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