A pipeline weld joint leakage monitoring device and a monitoring method thereof

Abstract

The application discloses a pipeline weld joint leakage monitoring device and a monitoring method thereof. The pipeline weld joint leakage monitoring device comprises a closed sensing cover, a pressure sensor and a heat protection layer. The closed sensing cover is wrapped outside a weld joint of a pipeline to be detected. An air nozzle capable of being connected with a pump body is arranged on the closed sensing cover. The pressure sensor is arranged on an inner side wall of the closed sensing cover. The heat protection layer is wrapped outside the closed sensing cover and the pipeline to be detected. The pipeline weld joint leakage monitoring device and the monitoring method thereof provided by the application have high sensitivity, can detect the leakage in the early stage of the weld joint, can accurately locate the leakage position, do not need large-area excavation and checking, and are low in cost.

Description

Technical Field

[0001] This application relates to the field of pipeline leakage detection technology, and in particular to a pipeline weld joint leakage monitoring device and monitoring method. Background Technology

[0002] A district cooling system (DCS) prepares low-temperature chilled water (typically 3°C to 12°C) at a cooling station and distributes it to heat exchange stations at each user end via a primary pipeline network, providing a centralized cooling source for building complexes. Compared to decentralized air conditioning, district cooling offers advantages such as high energy efficiency, environmental friendliness, and ease of management and maintenance, and has become the mainstream cooling mode for high-density building clusters such as large business districts, airports, high-speed rail stations, and data centers.

[0003] District cooling primary networks typically use directly buried prefabricated insulated pipes. Throughout the entire lifecycle of these pipes, the on-site weld joints are the most likely points of leakage and failure. However, due to the low temperature of the medium inside the cooling pipeline, the absence of vapor phase change, and the stable operating pressure, leaks at the weld joints are often difficult to detect. Therefore, they can only be discovered passively through periodic excavation and inspection, which is costly. Summary of the Invention

[0004] This application aims to at least solve one of the aforementioned technical problems existing in the prior art. Therefore, the purpose of this application is to provide a pipeline weld joint leakage monitoring device and method, which is not only highly sensitive, enabling early detection of leaks at the weld joint, but also accurately locates the leak position without requiring large-scale excavation for investigation, and is low in cost.

[0005] To achieve the above objectives, the technical solution adopted in this application is as follows: This application provides a pipeline weld joint leakage monitoring device, comprising: A sealed sensing cover is wrapped around the weld joint of the pipe to be tested to form a sealed sensing space. The sealed sensing cover is equipped with an air nozzle that can be connected to the pump body to adjust the air pressure in the sensing space. A pressure sensor is disposed within the sensing space to detect pressure changes within the sensing space and transmit the detected pressure signal to an external reading device; An insulating protective layer is wrapped around the outside of the sealed sensing cover and the pipe to be tested, in order to protect the sealed sensing cover and the pipe to be tested.

[0006] This application provides a pipeline weld joint leakage monitoring device, which has at least the following advantages: By setting a sealed sensing cover on the outer wall of the weld joint of the pipeline to be inspected to form a sealed sensing space, and the sealed sensing cover is connected to a pump body through an air nozzle to adjust the air pressure value of the sensing space, a pressure sensor is set in the sensing space. When leakage occurs at the weld joint of the pipeline to be inspected, causing a change in air pressure in the sensing space, the pressure sensor can detect the pressure change in the sensing space and transmit the detected pressure signal to an external reading device. This allows even a slight leak at the weld joint of the pipeline to be inspected to be accurately identified by the pressure sensor, with high sensitivity, thus achieving early warning several weeks to months earlier than visible leaks. In addition, since each pressure sensor has a unique physical address, it has the ability to locate a single weld joint. After an alarm, it directly points to the specific weld joint coordinates, thereby accurately locating the leak location without the need for large-scale excavation and investigation, resulting in low cost.

[0007] Optionally, the pipeline weld leakage monitoring device further includes an outlet device, which is disposed on the thermal insulation layer and electrically connected to the pressure sensor for transmitting the signal of the pressure sensor to the external reading device.

[0008] Optionally, a conduit is embedded in the thermal insulation layer, and the wire of the pressure sensor passes through the conduit and is electrically connected to the lead-out device.

[0009] Optionally, the thermal insulation protective layer includes an insulation layer and an outer sleeve. The insulation layer wraps around the outside of the sealed sensing cover and the pipe to be tested, and the outer sleeve wraps around the outside of the insulation layer. Optionally, the lead-out device is configured as any one of a waterproof junction box, an optical fiber lead-out terminal, or an electromagnetic coupling coil.

[0010] This application also provides a method for monitoring leaks at pipe weld joints, based on a pipe weld joint leak monitoring device, comprising the following steps: The pressure sensor is installed inside the sealed sensing cover, and the wire of the pressure sensor is led out from the groove reserved on the edge of the sealed sensing cover; The sealed sensing cover is fastened to the weld joint of the pipe to be tested to form a sealed sensing space inside the sealed sensing cover. Then the air pressure value of the sensing space is adjusted to a preset pressure value, and a pressure baseline is established based on the preset pressure value. The thermal insulation protective layer is wrapped around the outside of the sealed sensing cover and the pipe to be tested; Connect the wires of the pressure sensor to the external reading device. When the pressure sensor detects that the air pressure value in the sensing space continuously deviates from the pressure baseline, it can be determined that the weld joint is leaking, and the external reading device sends an alarm signal to the terminal.

[0011] This application provides a method for monitoring leaks at pipe weld joints, which has at least the following advantages: By setting a pressure sensor in the sensing space and adjusting the air pressure in the sensing space to a preset value before detection, when a leak occurs at the weld joint of the pipe to be detected, causing a change in the air pressure within the sensing space, the pressure sensor can detect the pressure change and transmit the detected pressure signal to an external reading device. When the pressure sensor detects that the air pressure value in the sensing space continuously deviates from the pressure baseline, it can determine that a leak has occurred at the weld joint. This allows even minor leaks at the weld joint of the pipe to be detected to be accurately identified by the pressure sensor, demonstrating high sensitivity and enabling early warning several weeks to months earlier than visible leaks. Furthermore, since each pressure sensor has a unique physical address and single weld joint location capability, it directly points to the specific weld joint coordinates after an alarm, thereby accurately locating the leak location without the need for large-scale excavation and investigation, resulting in low cost.

[0012] Optionally, installing the sealed sensing cover includes: Apply sealant symmetrically to the pipe to be tested on both sides of the weld joint to form a sealing ring, so that the two flanges of the sealed sensing cover are pressed into the sealing ring to ensure that there are no air bubbles or gaps between the flanges and the pipe wall of the pipe to be tested.

[0013] Optionally, installing the sealed sensing cover includes: When the preset pressure value is lower than the ambient air pressure, the pump body is set as a negative pressure pump. The output end of the negative pressure pump is connected to the air nozzle. The negative pressure pump extracts the air in the sensing space to a relative vacuum of ≤-0.06MPa through the air nozzle. Then, the negative pressure pump is removed and the air nozzle is sealed to prevent backflow.

[0014] Optionally, installing the sealed sensing cover includes: When the preset pressure value is higher than the ambient air pressure, the pump body is set as a positive pressure pump. The output end of the positive pressure pump is connected to the air nozzle. The positive pressure pump fills the sensing space with dry nitrogen gas through the air nozzle to a slight positive pressure of 0.01~0.03MPa. Then the positive pressure pump is removed and the air nozzle is sealed to prevent external humid air from seeping in.

[0015] Optionally, installing the sealed sensing cover includes: When the preset pressure value is equal to the ambient air pressure, the output end of the pump body is not connected to the air nozzle, and the air nozzle is directly sealed so that the sensing space maintains the ambient air pressure at the time of installation. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of a pipeline weld leakage monitoring device provided in Example 1; Figure 2 for Figure 1 A magnified view of a section at point A in the middle; Figure 3 This is a flowchart of a pipeline weld leakage monitoring method provided in Example 2.

[0017] 100. Pipeline to be inspected; 110. Weld joint; 200. Sealed sensor cover; 210. Sensing space; 220. Air nozzle; 300. Pressure sensor; 400. Thermal insulation protective layer; 410. Thermal insulation layer; 420. Outer jacket; 500. Extraction device; 600. Conduit. Detailed Implementation

[0018] The embodiments of this application are described in detail below with reference to the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application.

[0019] In the description of this application, it should be understood that the terms "center", "middle", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0020] In the description of this application, "several" means one or more, "multiple" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. The use of "first" and "second" in the description is merely for distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0021] In the description of this application, unless otherwise expressly specified and limited, the terms "set up," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0022] In the description of this application, the use of terms such as "one embodiment," "some embodiments," "an example," "some instances," "some embodiments," "illustrative embodiment," "example," "specific example," "some examples," etc., indicates that the specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0023] Example 1 See attached document Figure 1 and attached Figure 2 This embodiment provides a pipeline weld leak monitoring device, including: A sealed sensing cover 200 is wrapped around the weld joint 110 of the pipe 100 to be inspected, forming a sealed sensing space 210. The pipe 100 to be inspected is a direct-buried pre-insulated pipe used to transport low-temperature chilled water to a cooling station. The ends of the two pipes 100 to be inspected are usually fixed by welding, which forms an annular weld joint 110 after welding. The sealed sensing cover 200 is made of a 0.3~0.8mm thick stainless steel or aluminum alloy arc-shaped sheet, and the curvature of the sealed sensing cover 200 matches the curvature of the outer wall of the pipe 100 to be inspected. The length of the sealed sensing cover 200 along the axial direction of the pipe 100 to be inspected is 50~150mm, so that it can cover the weld joint 110 and the heat-affected zones on both sides, and the radial height is 2~5mm. The sealed sensing cover 200 has flanged structures on both sides. When installing the sealed sensing cover 200, sealant is symmetrically applied to the pipe 100 to be tested on both sides of the weld joint 110 to form a sealing ring, so that the flanges on both sides of the sealed sensing cover 200 are pressed into the sealing ring to ensure that there are no air bubbles or gaps between the flanges and the pipe wall. The sealed sensing cover 200 is provided with a nozzle 220 that can be connected to the pump body for adjusting the air pressure in the sensing space 210. The nozzle 220 is preferably a copper valve with a diameter of 3mm, and a one-way valve is provided inside, so that the nozzle 220 can only exhaust or intake air in one direction. At least two nozzles 220 are provided, one for inflation and one for extraction. Pressure sensor 300 is disposed within sensing space 210 to detect pressure changes within sensing space 210 and transmit the detected pressure signal to an external reading device. Pressure sensor 300 employs a MEMS piezoresistive pressure sensor, a miniature absolute pressure sensor, or a pressure-humidity composite sensor. Its dimensions are no larger than Φ15mm×8mm, its range is 0.01MPa, its accuracy is ±0.5%FS, its operating temperature is -20~60℃, and its package rating is IP67 or higher. When pressure sensor 300 is a pressure-humidity composite sensor, it can simultaneously detect air pressure and humidity within sensing space 210. The thermal insulation protective layer 400 is wrapped around the outside of the sealed sensing cover 200 and the pipe to be tested 100. When the pipe to be tested 100 is buried underground, it is used to protect the sealed sensing cover 200 and the pipe to be tested from damage such as corrosion. In some embodiments, refer to the appendix Figure 2 The pipeline weld leakage monitoring device also includes an output device 500, which is installed on the thermal insulation layer 400. The output device 500 is electrically connected to the pressure sensor 300 and is used to transmit the signal of the pressure sensor 300 to an external reading device.

[0024] In some embodiments, refer to the appendix Figure 2 A conduit 600 is embedded within the thermal insulation layer 400. The conduit 600 is preferably a stainless steel pipe with a diameter of 10-16 mm. The wires of the pressure sensor 300 pass through the conduit 600 and are electrically connected to the lead-out device 500. The connection between the wires of the pressure sensor 300 and the terminals of the lead-out device 500 is pluggable. During maintenance, the lead-out device 500 can be removed from the thermal insulation layer 400 to test the continuity of the circuits of both the pressure sensor 300 and the lead-out device 500, facilitating timely repair or replacement in case of damage.

[0025] In some embodiments, refer to the appendix Figure 2The thermal insulation protective layer 400 includes an insulation layer 410 and an outer sleeve 420. The insulation layer 410 is made of rigid polyurethane foam that has been foamed and filled on-site, or it can be made of other insulation materials. The insulation layer 410 wraps around the outside of the sealed sensing cover 200 and the pipe 100 to be tested. It can use the foaming pressure to press the flange of the sealed sensing cover 200 tightly from the outside, so that the sealant can further fill the gap between the flange of the sealed sensing cover 200 and the pipe wall of the pipe 100 to be tested before curing, thereby achieving a further seal. The outer sleeve 420 is a PE (polyethylene) heat shrink sleeve or electrofusion sleeve with a length of 150~250mm. The outer sleeve 420 wraps around the outside of the insulation layer 410 to protect the insulation layer 410 from scratches by hard objects (such as stones) and avoid affecting the insulation effect. The lead-out device 500 is disposed on the thermal insulation layer 400. The lead-out device 500 is electrically connected to the pressure sensor 300 and is used to lead out the signal of the pressure sensor 300 to an external reading device.

[0026] In some embodiments, refer to the appendix Figure 2 The lead-out device 500 is configured as any one of a waterproof junction box, an optical fiber lead-out terminal, or an electromagnetic coupling coil. When the lead-out device 500 is a waterproof junction box, a mounting hole is made in the outer sleeve 420, and the waterproof junction box is installed in the mounting hole, thereby fixing the waterproof junction box to the outer sleeve 420. The waterproof junction box is made of stainless steel or high-strength engineering plastic, with a protection rating of IP68 and a pressure resistance greater than or equal to 50kN. A wiring terminal is provided inside the waterproof junction box, and the wire of the pressure sensor 300 passes through the conduit 600 and is electrically connected to the wiring terminal. When the lead-out device 500 is an optical fiber lead-out terminal, the pressure sensor 300 uses an optical fiber pressure sensing head, such as an FBG (Fiber Bragg grating) sensor or an optical fiber Fabry-Perot cavity sensor. The pressure sensor 300 and the optical fiber lead-out terminal are connected via a plug-in connection. One end of the armored short optical fiber can be connected to the optical fiber lead-out terminal, and the other end can be led out from the side wall of the outer sleeve 420 to the valve well or inspection well and connected to the photoelectric conversion module. When the lead-out device 500 is an electromagnetic coupling coil, the pressure sensor 300 uses a passive inductive-capacitive (LC) resonant pressure sensor. The electromagnetic coupling coil is located on the outer sleeve 420 at a position corresponding to the pressure sensor 300. The electromagnetic coupling coil can be made of copper foil or a printed coil. The coil lead is led out along the inner wall of the outer sleeve 420 to a position accessible to the ground. The pressure signal of the pressure sensor 300 is read from the ground by electromagnetic induction using a handheld or fixed reader / writer.

[0027] Example 2 See attached document Figure 3This embodiment provides a method for monitoring leaks at pipe weld joints, based on a pipe weld joint leak monitoring device of Embodiment 1, including the following steps: Step 1, Pre-treatment of weld joint 110: 11) After the welding of the pipeline to be inspected 100 is completed on site and passes the non-destructive testing, and before the on-site foaming insulation construction, use an electric wire brush or sandpaper to remove rust from the weld joint 110 and the outer wall of the pipeline to be inspected within 100mm on both sides. The rust removal level must reach St3 level.

[0028] 12) Clean the surface of the pipe 100 and weld 110 to be tested with anhydrous ethanol or acetone to remove oil, moisture and welding spatter.

[0029] 13) After air drying or hot air drying, ensure that the surface moisture content of the pipe 100 and weld 110 to be tested is less than 5%. The test method can be based on visual inspection and no water stains or dampness when touched.

[0030] Step 2: Install pressure sensor 300. 21) Install the pressure sensor 300 in the center of the sealed sensing cover 200, and ensure that the pressure-sensing surface of the pressure sensor 300 faces the inner cavity of the sealed sensing cover 200. At the same time, lead the wire of the pressure sensor 300 out from the groove reserved on the edge of the sealed sensing cover 200.

[0031] Step 3: Install the sealed sensor cover 200: 31) The sealant should be butyl rubber sealant or silicone structural sealant. The sealant should have a Shore hardness of 20~30A and a temperature resistance of -40~+150℃. 32) Apply sealant symmetrically to the outer wall of the pipe to be inspected, 40-60mm on each side of the weld joint 110, to form a sealing ring. The sealing ring consists of an inner ring and an outer ring, with a width of 10-15mm, a thickness of 1.5-2.0mm, and a spacing of 20mm. The inner and outer rings form a double-seal structure.

[0032] 33) After application, let it stand for 5 to 10 minutes to allow the sealant to form an initial adhesive film on the surface, but keep the underlying layer moist to provide fluidity.

[0033] 34) Align the sealed sensing cover 200 with the center of the weld 110 and fasten it to the outer wall of the pipe to be tested 100, so that the two sides of the sealed sensing cover 200 are pressed into the sealing ring. Then use a rubber roller to roll along the circumference of the sealed sensing cover 200 3 to 5 times to ensure that there are no air bubbles or gaps between the flanges and the pipe wall of the pipe to be tested 100, so as to form a sealed sensing space 210 inside the sealed sensing cover 200.

[0034] 35) At least two air nozzles 220 are reserved on the sealed sensing cover 200. Each air nozzle 220 has a built-in one-way valve, one for subsequent vacuuming operation and the other for subsequent pre-filling operation.

[0035] 36) Adjust the air pressure value of the sensing space 210 to the preset pressure value: When the preset pressure value is lower than the ambient air pressure, the pump body is set as a negative pressure pump. The output end of the negative pressure pump is connected to one of the air nozzles 220. The negative pressure pump extracts the air in the sensing space 210 through the air nozzle 220 to a relative vacuum of ≤-0.06MPa. Then the negative pressure pump is removed and the air nozzle 220 is sealed to prevent backflow.

[0036] When the preset pressure value is higher than the ambient air pressure, the pump body is set as a positive pressure pump. The output end of the positive pressure pump is connected to another air nozzle 220. The positive pressure pump fills the sensing space 210 with dry nitrogen through the air nozzle 220 to a slight positive pressure of 0.01~0.03MPa (that is, the air pressure inside the sensing space 210 is 0.01~0.03MPa higher than the external ambient atmospheric pressure). Then the positive pressure pump is removed and the air nozzle 220 is sealed to prevent external humid air from seeping in.

[0037] When the preset pressure value is equal to the ambient air pressure, the output end of the pump body is not connected to any air nozzle 220, and the air nozzle 220 is directly sealed, so that the sensing space 210 maintains the ambient air pressure at the time of installation.

[0038] A pressure baseline is established using a preset pressure value. Since the air pressure within the sensing space 210 is affected by ambient temperature, changes in ambient temperature cause the gas within the sensing space 210 to expand or contract, resulting in a synchronous change in air pressure. Because the environmental conditions at each weld 110 are not entirely the same, an independent pressure baseline needs to be established for each weld 110, and the correlation between the pressure baseline and ambient temperature needs to be recorded. This allows for the determination of the pressure baseline of the sensing space 210 at the corresponding weld 110 during subsequent testing, ensuring the accuracy of the test results. Ambient temperature includes the temperature of the medium within the pipeline 100 under test and the soil temperature.

[0039] Step 4: Install the 400mm thermal insulation layer. 41) Use high-temperature resistant aluminum foil tape with a temperature resistance of ≥120℃ to temporarily fix both sides of the sealed sensing cover 200 to prevent the insulation layer 410 from shifting before foaming.

[0040] 42) Lay the conduit 600 along the outer wall of the pipe 100 to be tested on the sealed sensing cover 200 and secure it with stainless steel cable ties. The distance between the conduit 600 and the outer wall of the pipe 100 to be tested is 200mm to ensure that the conduit 600 will not shift due to buoyancy when the insulation layer 410 is foamed. One end of the conduit 600 is aligned with the groove reserved on the edge of the sealed sensing cover 200, and the other end of the conduit 600 is bent and extends in a direction perpendicular to the pipe 100 to be tested.

[0041] 43) Rigid polyurethane foam is foamed on-site using a high-pressure foaming machine, with the foaming density controlled at 60~80 kg / m³. The foaming material is injected from one side of the sealed sensing cover 200, flowing and filling the external space of the sealed sensing cover 200. After the foaming material cures, the insulation layer 410 is obtained. At this time, the sealed sensing cover 200 is wrapped inside the insulation layer 410, and the conduit 600 is simultaneously covered and fixed. Since the sealed sensing cover 200 is a rigid metal structure, the foaming pressure is uniformly pressed from the outside to the two sides of the sealed sensing cover 200, so that the sealant further fills the micro gaps before curing, thereby achieving further sealing.

[0042] 44) The outer sleeve 420 is made of PE (polyethylene) heat shrink sleeve or electrofusion sleeve, and covers the weld joint 110 and the outer wall of the pipe 100 to be tested on both sides by 150~250mm. The top of the outer sleeve 420 is provided with an opening with a diameter of 25~35mm. The other end of the conduit 600 extends to the opening and protrudes 30~50mm beyond the outer protective tube to ensure that the wire of the pressure sensor 300 can be connected to the lead-out device 500 after passing through the conduit 600. The gap between the conduit 600 and the opening of the outer sleeve 420 is filled with hot melt glue stick or polyurethane sealant for waterproofing. Step 5: Install lead-out device 500: 51) Fix the lead-out device 500 on the outer sleeve 420 of the thermal insulation protective layer 400, and electrically connect the wire of the pressure sensor 300 to the lead-out device 500. Then the pipe to be tested 100 can be buried in the soil.

[0043] Step 6, Leak Detection: 61) By periodically or continuously reading the pressure data at each weld joint 110 through the lead-out device 500, when the pressure sensor 300 detects that the air pressure in the sensing space 210 is continuously deviating from the pressure baseline, it can be determined that the weld joint 110 is leaking.

[0044] Specifically, at least one of the following criteria is used to determine leakage: Trend deviation criterion: Monitor the cumulative rate of change of pressure in the sensing space 210 over time. When the pressure value at a certain weld joint 110 continuously deviates from its baseline value and the rate of change exceeds the set threshold, for example, ΔP / Δt>5Pa / h, where ΔP is the air pressure difference value in the sensing space 210 over a certain period of time and Δt is the time difference over a certain period of time, it can be determined that there is micro-seepage in the weld joint 110. Pressure following criteria: When a controllable pressure disturbance is performed in the cooling station (such as starting and stopping the circulating pump, adjusting the valve opening), monitor whether the pressure in the sensing space 210 at each weld 110 shows a change in phase and trend with the pressure fluctuation in the pipeline 100 to be tested; if the pressure in the sensing space 210 at a certain weld 110 produces a distinguishable response to the pressure step in the pipeline 100 to be tested, it indicates that there is a pressure communication channel between the sensing space 210 at the weld 110 and the pipeline 100 to be tested, and it is determined that a through crack has been generated in the weld 110; Differential criterion: Compare the pressure values ​​or rate of change at adjacent welds 110 on the same pipeline 100 to be inspected. When the pressure characteristics at a certain weld 110 deviate significantly from the statistical benchmark of the adjacent welds 110 and the pipeline 100 to be inspected, while the adjacent welds 110 remain stable, it is determined that the weld 110 is abnormal.

[0045] 62) When a leak is detected at weld joint 110, the external reading device sends an alarm signal to the terminal (such as the SCADA system of the cooling station; SCADA system, or Supervisory Control and Data Acquisition, is a computer-based control system used to collect, analyze and manage real-time data of industrial equipment, and to monitor and control industrial processes through software and hardware) and retrieves the flow rate, differential pressure and water replenishment data of the pipe section. If the weld joint 110 alarm occurs at the same time as the abnormal water replenishment in the station and the increased pressure drop in the pipe section, the leak is confirmed and the emergency plan is activated.

[0046] This application also has at least the following beneficial effects: 1. High sensitivity, enabling early warning of leaks: By installing a sealed sensing cover 200 on the outer wall of the weld joint 110, water seepage is confined within the sealed sensing cover 200. Even if the leakage rate is small, a discernible pressure trend deviation can be generated within several hours. At the same time, by utilizing pressure following criteria, anomalies can be detected through pressure transmission characteristics when there is no obvious water seepage in the weld joint 110 and only through-hole microcracks exist, achieving early warning weeks to months earlier than visible leakage.

[0047] 2. Precise positioning, no need for large-scale excavation and inspection: By independently setting pressure sensors 300 at each weld joint 110, each sensor has a unique physical address and has the ability to locate a single weld joint 110. After an alarm is triggered, it directly points to the coordinates of the specific weld joint 110, which can reduce the scope of emergency repair excavation from the entire trench to a single weld joint work pit, greatly reducing maintenance costs and the impact on municipal traffic.

[0048] 3. Low cost: By selecting the time of installation of this device after the steel pipe welding is completed and the non-destructive testing is qualified, and before the on-site foam insulation construction, the device is buried underground together with the pipeline to be tested after installation. The pipeline leakage can be monitored without digging it out later.

[0049] 4. Accurate Detection: By combining multiple criteria such as trend deviation criterion, pressure following criterion, and differential criterion, when the pressure sensor 300 is a pressure-humidity composite sensor, it can effectively distinguish: 1) When the pressure and humidity in the sensing space 210 increase, it can be determined as micro-seepage at the weld joint; 2) When the humidity in the sensing space 210 increases and the pressure remains unchanged, it can be determined as water ingress due to damage to the outer casing; 3) When the humidity and pressure in the sensing space 210 of the entire pipeline change synchronously, it can be determined as normal pressure fluctuation in the pipe; 4) When the pressure and humidity data in the sensing space 210 drift slowly at a single point but without following, it can be determined as sensor drift.

[0050] The above embodiments are preferred embodiments of this application, but the implementation of this application is not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of this application shall be considered equivalent substitutions and shall be included within the protection scope of this application.

Claims

1. A pipe weld leak monitoring device, characterized in that, include: A sealed sensing cover is wrapped around the weld joint of the pipe to be tested to form a sealed sensing space. The sealed sensing cover is equipped with an air nozzle that can be connected to the pump body to adjust the air pressure in the sensing space. A pressure sensor is disposed within the sensing space to detect pressure changes within the sensing space and transmit the detected pressure signal to an external reading device; An insulating protective layer is wrapped around the outside of the sealed sensing cover and the pipe to be tested, in order to protect the sealed sensing cover and the pipe to be tested.

2. The pipeline weld joint leakage monitoring device according to claim 1, characterized in that: The pipeline weld leakage monitoring device also includes an outlet device, which is disposed on the thermal insulation layer and electrically connected to the pressure sensor for transmitting the signal of the pressure sensor to the external reading device.

3. The pipeline weld joint leakage monitoring device according to claim 2, characterized in that: A conduit is embedded in the thermal insulation layer, and the wire of the pressure sensor passes through the conduit and is electrically connected to the lead-out device.

4. The pipeline weld joint leakage monitoring device according to claim 3, characterized in that: The thermal insulation protective layer includes an insulation layer and an outer tube. The insulation layer is wrapped around the outside of the sealed sensing cover and the pipe to be detected, and the outer tube is wrapped around the outside of the insulation layer.

5. A pipeline weld joint leakage monitoring device according to claim 2, characterized in that: The lead-out device is configured as any one of a waterproof junction box, an optical fiber lead-out terminal, or an electromagnetic coupling coil.

6. A method for monitoring leaks at pipe weld joints, based on a pipe weld joint leak monitoring device according to any one of claims 1 to 5, characterized in that, Includes the following steps: The pressure sensor is installed inside the sealed sensing cover, and the wire of the pressure sensor is led out from the groove reserved on the edge of the sealed sensing cover; The sealed sensing cover is fastened to the weld joint of the pipe to be tested to form a sealed sensing space inside the sealed sensing cover. Then the air pressure value of the sensing space is adjusted to a preset pressure value, and a pressure baseline is established based on the preset pressure value. The thermal insulation protective layer is wrapped around the outside of the sealed sensing cover and the pipe to be tested; Connect the wires of the pressure sensor to the external reading device. When the pressure sensor detects that the air pressure value in the sensing space continuously deviates from the pressure baseline, it can be determined that the weld joint is leaking, and the external reading device sends an alarm signal to the terminal.

7. A method for monitoring leakage at pipe weld joints according to claim 6, characterized in that: The installation of the sealed sensing cover includes: Apply sealant symmetrically to the pipe to be tested on both sides of the weld joint to form a sealing ring, so that the two flanges of the sealed sensing cover are pressed into the sealing ring to ensure that there are no air bubbles or gaps between the flanges and the pipe wall of the pipe to be tested.

8. The method for monitoring leakage at pipe weld joints according to claim 6, characterized in that: The installation of the sealed sensing cover includes: When the preset pressure value is lower than the ambient air pressure, the pump body is set as a negative pressure pump. The output end of the negative pressure pump is connected to the air nozzle. The negative pressure pump extracts the air in the sensing space to a relative vacuum of ≤-0.06MPa through the air nozzle. Then, the negative pressure pump is removed and the air nozzle is sealed to prevent backflow.

9. A method for monitoring leakage at pipe weld joints according to claim 6, characterized in that: The installation of the sealed sensing cover includes: When the preset pressure value is higher than the ambient air pressure, the pump body is set as a positive pressure pump. The output end of the positive pressure pump is connected to the air nozzle. The positive pressure pump fills the sensing space with dry nitrogen gas through the air nozzle to a slight positive pressure of 0.01~0.03MPa. Then the positive pressure pump is removed and the air nozzle is sealed to prevent external humid air from seeping in.

10. A method for monitoring leakage at pipe weld joints according to claim 6, characterized in that: The installation of the sealed sensing cover includes: When the preset pressure value is equal to the ambient air pressure, the output end of the pump body is not connected to the air nozzle, and the air nozzle is directly sealed so that the sensing space maintains the ambient air pressure at the time of installation.

Images