An electrode assembly and a detection device

Abstract

This utility model discloses an electrode assembly and a detection device. The working electrode, auxiliary electrode and reference electrode of the electrode assembly all include an insulating cylinder and an electrode core housed in the insulating cylinder. The insulating cylinder includes a tail extending out of the pipe to be tested and a head embedded in the pipe to be tested. The electrode core is exposed from the front end of the head and can contact the fluid in the pipe to be tested to obtain an electrochemical signal, so as to accurately detect the corrosion and scaling state of the inner wall of the pipe to be tested.

Description

Technical Field

[0001] This utility model relates to the monitoring of pipeline corrosion and scale conditions, and more specifically, to an electrode assembly and a detection device. Background Technology

[0002] Providing clean drinking water depends on the stable operation of urban water supply systems. Water supply pipelines, serving as the "lifeline" of a city, are a crucial link in this system and a strategically important urban infrastructure. Iron-based pipes are the most common type of pipe in domestic and international water supply networks. However, over long-term use, the inner walls of iron pipelines undergo corrosion, forming iron scale, primarily composed of iron oxides. Normally, this scale adheres stably and tightly to the inner walls of the pipelines. However, when water quality or hydraulic conditions change, the scale dissolves and breaks down, releasing iron oxides into the water, causing water quality deterioration. This process is often accompanied by the release of metals from within the scale, leading to problems such as excessive color, turbidity, iron and manganese content, and microbial contamination in the effluent, seriously affecting water supply safety.

[0003] The self-corrosion of iron water supply pipelines under test mainly begins with pitting corrosion. Due to certain crystal defects on the surface of the metal substrate, the charge is concentrated at these defects, making them prone to electrochemical reactions that produce pitting pits. Strong corrosion currents can be observed at these pits. During pitting corrosion, metallic Fe(O) reacts electrochemically with oxidizing substances in the water, such as dissolved oxygen and free chlorine, to form Fe2+. 2+ Subsequently, further reactions produce ferroalloy oxide products such as γ-FeOOH. The γ-FeOOH inside the scale is relatively unstable, and its loose, porous structure provides ample oxidant reaction sites, promoting further corrosion. As corrosion progresses, the γ-FeOOH in the scale gradually transforms into the more stable goethite (α-FeOOH). Various iron oxides, such as hematite (Fe2O3), magnetite (Fe3O4), and siderite (FeCO3), further appear in the scale. On the surface of the metal scale, calcium carbonate particles co-precipitate with Fe(III) and Fe(II), forming a loose, porous granular layer, including various amorphous iron oxides such as Fe(OH)3, Fe(OH)2, and Fe2O3. During this process, the redox potential and corrosion current of the metal continuously fluctuate, effectively reflecting the electrochemical reaction process of the metal substrate. Simultaneously, the formation of iron oxide deposits on the metal surface can also alter the capacitive reactance characteristics of the inner metal wall surface.

[0004] As corrosion progresses, a stable scale layer forms on the inner surface of the iron-containing water supply pipe under test. This scale layer is a relatively stable multilayered structure. According to the classic pipe scale model proposed by Sarin, pipe scale is a stable multilayered structure, including: (1) a metallic substrate Fe(O); (2) a porous layer containing various iron oxides; (3) a dense layer mainly composed of dense Fe3O4 crystals; and (4) a loose deposition layer mainly composed of amorphous or small particulate components such as Fe(OH)3 and CaCO3. The special layered structure of pipe scale enables it to exhibit a stable capacitive reactance signal.

[0005] Besides self-corrosion, galvanic corrosion often occurs at the joints of pipes made of different materials, as well as near the joints with valves and other components, due to the differences in metal materials. Galvanic corrosion rates are usually higher than self-corrosion rates and have a significant impact on the localized corrosion of water supply pipes under test.

[0006] Iron release from iron-containing water supply pipes should be considered a process relatively independent of corrosion. It is usually not directly caused by metal oxidation, but rather by the dissolution of loose, porous iron oxides within the pipe scale. When the scale ruptures under specific conditions, the internal iron oxides dissolve and diffuse into the water, causing iron release. The released Fe(II) is oxidized and deposited, forming particulate iron oxides along with other Fe(III) oxides, resulting in a noticeable "yellow water" phenomenon in the pipe network.

[0007] Iron scale itself undergoes dissolution and iron diffusion through redox reactions. According to Kuch's Law, the surface of a metal pipe under test with stable scale will undergo continuous corrosion and scale dissolution under low redox conditions, the mechanism of which is an electrochemical reaction. Studies have confirmed through electrochemical corrosion potential and current that high-valence iron oxides can effectively act as cathodes, forming a galvanic cell with elemental iron as the anode, producing a significant redox reaction. Furthermore, sudden changes in water quality and hydraulic properties in pipe networks often lead to scale rupture in pipe walls. Water source switching and saltwater intrusion are typical scenarios of water quality change. Many water quality factors can affect iron release.

[0008] For water supply companies, it is not only necessary to understand the corrosion on the outer wall of the pipe to be tested, but also to know the corrosion, scaling, and scale rupture status of the inner wall of the pipe. By assessing the corrosion and iron release of the pipe to be tested in the water supply, and by recognizing the early signs of yellow water problems in a timely manner, timely treatment measures can be taken, which has important practical production guidance significance.

[0009] However, traditional methods for monitoring the stability of water supply networks often rely on changes in the total iron concentration of the effluent after simulating a pipe section operating for an extended period, reflecting a cumulative corrosion process. The widely used gravimetric analysis (GFA) calculates the corrosion rate by comparing the weight difference of the tested pipe before and after corrosion, also reflecting a cumulative amount. This method struggles to accurately characterize the instantaneous reaction rate of ferrous pipes and the real-time state of scale buildup. Furthermore, studying actual pipes requires destructive excavation and reactor construction, making it impossible to accurately simulate the actual condition of the pipe in real time.

[0010] Since the corrosion and iron release of the iron water supply pipeline under test is an electrochemical reaction process, electrochemical testing methods can be used to detect the changes in electrochemical signals of the corrosion process and corrosion products of the iron water supply pipeline under test, thereby reflecting the corrosion process and tendency.

[0011] Currently, electrochemical measurement methods have been applied to corrosion studies of pipelines in various environments such as geothermal water and oil and gas, characterizing the erosion state of the pipeline through electrical signals. Examples include resistance metal probes and potential array methods.

[0012] A resistance metal probe is inserted into the pipe under test, and the change in probe resistance reflects the degree of corrosion of the metal surface. However, as an invasive probe, its placement significantly affects the local flow pattern in the pipe, influencing the corrosion process and failing to characterize the state of the surface metal oxide deposits resulting from corrosion. Furthermore, for pipe sections already showing some corrosion, the probe's corrosion level cannot reflect the historical cumulative corrosion amount.

[0013] The potentiometric array method directly connects probes to the outer wall of the pipe network to form a resistance network. By measuring the resistance between pairs of electrodes, the corrosion characteristics of the pipe under test can be obtained. However, external surface corrosion can interfere with the potentiometric array method. In addition, the installation of probes requires excavation and modification of the water supply pipe under test, which involves a large amount of engineering work and is somewhat inconvenient to use.

[0014] In summary, existing methods for monitoring internal corrosion in water supply pipelines are insufficient for conveniently and accurately obtaining real-time corrosion current and corrosion rate in re-in service metal pipelines. Related electrochemical tests are primarily used for scenarios involving changes in the structure and properties of metallic materials, and have not been applied to research on the stability of actual water supply pipelines. Utility Model Content

[0015] This invention provides an electrode assembly and a detection device that can accurately characterize the changes in corrosion and scale on the inner wall of the pipe under test.

[0016] This utility model provides an electrode assembly, including: a working electrode, an auxiliary electrode, and a reference electrode. The working electrode, auxiliary electrode, and reference electrode are configured to be installed on the pipe to be tested and to detect the corrosion and scaling state of the inner wall of the pipe to be tested.

[0017] The working electrode, auxiliary electrode, and reference electrode all include an insulating cylinder and an electrode core housed within the insulating cylinder; the insulating cylinder includes a tail extending out of the test pipe and a head embedded in the test pipe, and the electrode core protrudes from the front end face of the head and can contact the fluid in the test pipe to obtain an electrochemical signal.

[0018] In an exemplary embodiment, the working surfaces of the electrode cores of the working electrode, auxiliary electrode, and reference electrode are radially expanded and aligned with the direction of the fluid in the pipe to be measured;

[0019] The working surfaces of the electrode cores of the working electrode, auxiliary electrode, and reference electrode are located on the inner wall of the pipe to be tested.

[0020] In an exemplary embodiment, the heads of the working electrode, auxiliary electrode, and reference electrode are all detachably embedded in the test pipe;

[0021] The working electrode, auxiliary electrode, and reference electrode all have external threads on their head sidewalls, which can be fitted with the internal threads of the corresponding holes in the pipe to be tested.

[0022] In one exemplary embodiment, the diameters of the electrode cores of the working electrode and the auxiliary electrode are equal;

[0023] The outer diameter range of the insulating cylinder of the working electrode, auxiliary electrode and reference electrode is greater than 1.0 cm and less than 2.0 cm.

[0024] In one exemplary embodiment, the electrode core of the working electrode is cylindrical and manufactured using the same substrate as the pipe to be tested; or,

[0025] The electrode core of the working electrode is manufactured from material taken from the pipe to be tested. The electrode core of the working electrode includes a working surface exposed inside the pipe to be tested, and the working surface has a corrosion scale layer on the inner wall of the pipe to be tested.

[0026] In an exemplary embodiment, the electrode core of the auxiliary electrode is disc-shaped and includes a first working surface exposed inside the pipe to be tested and a second working surface opposite to the first working surface;

[0027] The front end of the auxiliary electrode head is provided with a recess that extends into the inner cavity of the pipe to be tested and is used to install its own electrode core. The sidewall of the recess is provided with a plurality of connecting grooves along the circumference, which connect the inner cavity of the pipe to be tested and the recess, so that the fluid in the pipe to be tested flows into the second working surface of the auxiliary electrode through the connecting grooves.

[0028] In one exemplary embodiment, the reference electrode has a cylindrical electrode core, and the front end face of the reference electrode head has a receiving hole for accommodating its own electrode core.

[0029] This application provides a detection device, including an electrode assembly as described in any of the above embodiments and a detection device connected to the electrode assembly;

[0030] The detection device includes an electrochemical workstation connected to the electrode assembly and a computer connected to the electrochemical workstation.

[0031] In an exemplary embodiment, the detection device further includes a pipe to be tested, the pipe to be tested having a plurality of holes, the spacing between adjacent holes being less than 1.5 cm;

[0032] The heads of the working electrode, auxiliary electrode, and reference electrode of the electrode assembly are respectively installed in the corresponding holes.

[0033] In one exemplary embodiment, the working electrode, auxiliary electrode, and reference electrode are arranged at intervals along the water flow direction of the pipe under test, and the working electrode is located between the auxiliary electrode and the reference electrode; or

[0034] The working electrode, auxiliary electrode, and reference electrode are arranged at intervals along the circumference of the pipe to be tested, and the working electrode is located between the auxiliary electrode and the reference electrode.

[0035] The electrode assembly of this utility model embodiment can be embedded in the pipe to be tested and directly contact the fluid on the inner wall of the pipe to be tested, detect the hydraulic and water quality conditions on the inner wall of the pipe to be tested, thereby accurately collecting parameters of the corrosion of the inner wall of the pipe to be tested, and accurately characterizing the change process of corrosion and scale on the inner wall of the pipe to be tested.

[0036] The electrode assembly of this invention does not require destructive excavation of the pipeline under test, and the installation method is simple and highly applicable. Furthermore, the electrode assembly of this invention can continuously capture the electrochemical signal of the electrode core, accurately characterizing the corrosion rate and scale status of the pipeline under test in real time.

[0037] Other features and advantages of this invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of this invention can be realized and obtained by means of the structures particularly pointed out in the description and the drawings. Attached Figure Description

[0038] The accompanying drawings are provided to further understand the technical solution of this utility model and constitute a part of the specification. They are used together with the embodiments of this utility model to explain the technical solution of this utility model, and do not constitute a limitation on the technical solution of this utility model.

[0039] Figure 1 This is a schematic diagram illustrating the installation and connection of the detection equipment according to an embodiment of the present utility model;

[0040] Figure 2 This is a perspective view of the working electrode of the electrode assembly according to an embodiment of the present invention;

[0041] Figure 3 for Figure 2 A three-dimensional split view;

[0042] Figure 4 A perspective view of the auxiliary electrode of the electrode assembly according to an embodiment of the present utility model;

[0043] Figure 5 for Figure 4 A three-dimensional split view;

[0044] Figure 6 This is a perspective view of the reference electrode of the electrode assembly in an embodiment of the present invention.

[0045] Figure 7 for Figure 6 A three-dimensional split view;

[0046] Figure 8 This is a schematic diagram showing the arrangement of three electrodes of the electrode assembly in an embodiment of the present invention along the water flow direction of the pipe to be tested.

[0047] Figure 9 This is a schematic diagram showing the three electrodes of the electrode assembly of this utility model arranged circumferentially along the pipe to be tested, according to an embodiment of the present invention.

[0048] Reference numerals: Detection equipment-100; Working electrode-1; Auxiliary electrode-2; Reference electrode-3; Test pipe-4; Inner wall-40; Insulating cylinder-10, 20, 30; Electrode core-11, 21, 31; Terminal-12, 22, 32; Tail-101, 201, 301; Head-102, 202, 302; Computer-5; Electrochemical workstation-6; Working surface-110; First working surface-211; Second working surface-212; Recess-23; Connecting groove-24; Accommodation hole-303. Detailed Implementation

[0049] To make the objectives, technical solutions, and advantages of this utility model clearer, the embodiments of this utility model will be described in detail below with reference to the accompanying drawings. It should be noted that, unless otherwise specified, the embodiments and features described herein can be arbitrarily combined with each other.

[0050] like Figures 1-9 As shown, this embodiment of the present invention provides a detection device 100 for detecting the corrosion and scaling state of the inner wall 40 of the pipe 4 to be tested. The detection device 100 of this embodiment includes an electrode assembly and a detection device connected to the electrode assembly.

[0051] like Figure 1 As shown, the electrode assembly includes a working electrode 1, an auxiliary electrode 2, and a reference electrode 3. The working electrode 1, auxiliary electrode 2, and reference electrode 3 are installed on the pipe 4 to be tested and work together to detect the corrosion and scaling condition of the inner wall of the pipe 4.

[0052] The working electrode 1 (WE) of this embodiment is the core electrode of the electrode assembly, used to detect the location of metal corrosion reactions. The working electrode 1 is made of metal, such as Fe or Cu pipe metal, or a metal material with a corrosion scale layer cut from the actual pipe being tested. The auxiliary electrode 2 (CE) is used to close the current loop, ensuring charge conduction in the electrolyte. It is typically made of a highly conductive, inert material to avoid interference with the system from its own reaction. The auxiliary electrode 2 can be a platinum sheet electrode, or it can be a gold electrode, graphite electrode, or glassy carbon electrode. The reference electrode 3 (RE) provides a stable potential reference whose potential does not change with current. The reference electrode 3 can be a silver / silver chloride electrode (Ag / AgCl), or a calomel electrode (SCE), etc.

[0053] like Figures 2-7As shown, the working electrode 1, auxiliary electrode 2, and reference electrode 3 each include insulating cylinders 10, 20, and 30, and electrode cores 11, 21, and 31 housed within the insulating cylinders 10, 20, and 30. The insulating cylinders 10, 20, and 30 include tail sections 101, 201, and 301 extending beyond the test channel 4, and heads 102, 202, and 302 embedded within the test channel 4. The electrode cores 11, 21, and 31 protrude from the front faces of the heads 102, 202, and 302 and can contact the fluid within the test channel 4 to obtain an electrochemical signal. The fluid can be a liquid or a gas; in this embodiment, water is used as an example for detailed explanation.

[0054] It should be noted that: in the embodiment of this utility model, the front end face of each component of each electrode refers to the end face facing the inner cavity of the pipe 4 to be tested, and the rear end face refers to the end face facing away from the inner cavity of the pipe 4 to be tested.

[0055] The electrode assembly of this utility model embodiment can be embedded in the pipe under test 4 and directly contact the fluid at the inner wall 40 of the pipe under test 4, thereby accurately collecting parameters of the corrosion status of the inner wall 40 of the pipe under test 4, and accurately characterizing the corrosion and scale change process of the inner wall 40 of the pipe under test 4.

[0056] Compared to traditional methods that require destructive excavation of the test pipe 4 to analyze scale on its inner wall 40, the electrode assembly of this embodiment eliminates the need for destructive excavation of the test pipe 4, and the installation method is simple and highly applicable. Furthermore, the electrode assembly of this embodiment can continuously capture the electrochemical signals of the electrode cores 11, 21, and 31, allowing for precise real-time characterization of the corrosion rate and scale status of the test pipe 4, compared to traditional methods that involve scraping scale and performing structural characterization.

[0057] The electrode assembly of this utility model embodiment can be applied to multiple locations in residential communities and municipal pipelines, forming a comprehensive monitoring network for the corrosion status of residential communities and municipal water supply networks, and fully characterizing the corrosion process of the water supply network.

[0058] like Figure 1 As shown, the detection device of this utility model embodiment includes a computer 5 and an electrochemical workstation 6. The working electrode 1, the auxiliary electrode 2 and the reference electrode 3 also include terminals 12, 22 and 32 connected to the electrode cores 11, 21 and 31. The terminals 12, 22 and 32 are connected to the electrochemical workstation 6 through wires, and the electrochemical workstation 6 is connected to the computer 5.

[0059] In this embodiment of the invention, the electrode assembly consisting of a working electrode 1, an auxiliary electrode 2, and a reference electrode 3 forms a circuit with the working electrode 1 during electrochemical testing. The electrochemical workstation 6 provides a small current or voltage disturbance, and the voltage and current of the working electrode 1 are measured within the circuit, providing the electrochemical signal for evaluating the corrosion and scaling state of the pipeline under test. However, the potential difference between the working electrode 1 and the auxiliary electrode 2 is difficult to measure accurately due to electrode polarization (current causing potential drift). Therefore, a reference electrode 3 with a highly stable known potential (such as Ag / AgCl in KCl solution) is used. The reference electrode 3 has almost no current flow, avoiding the polarization effect. The potential of the working electrode 1 can be accurately measured relative to the stable reference point provided by the reference electrode 3, thus obtaining accurate experimental results. The electrochemical signal obtained by the electrode assembly includes the corrosion potential E. corr (V), corrosion current I corr (A / cm 2 High-resistivity or low-resistivity scale (binary variable), scale film resistance R f (Ω / cm 2 ), scale film capacitance C f (μF / cm 2 ), charge transfer resistance R ct (Ω / cm 2 ), double-layer capacitance C dl (μF / cm 2 and acceptor charge density N A or donor electron density N D (cm -3 Electrochemical indicators such as these are input into computer 5 for evaluation of the corrosion tendency and scale stability of the pipeline inner wall.

[0060] like Figure 1 As shown, in this embodiment of the present invention, the heads 102, 202, and 302 of the working electrode 1, auxiliary electrode 2, and reference electrode 3 are all detachably embedded into the test pipe 4. In this embodiment, the sidewalls of the heads 102, 202, and 302 of the working electrode 1, auxiliary electrode 2, and reference electrode 3 are all provided with external threads, which can be fitted with the internal threads of the corresponding holes in the test pipe 4 for installation. Therefore, the working electrode 1, auxiliary electrode 2, and reference electrode 3 can be easily disassembled and repaired with the corresponding holes on the test pipe 4.

[0061] like Figure 8 , Figure 9As shown, in this embodiment of the invention, the working surfaces of the electrode cores 11, 21, and 31 of the working electrode 1, auxiliary electrode 2, and reference electrode 3 are radially expanded. After installation, they can remain parallel to the fluid direction of the pipe under test 4, thereby ensuring the contact area with the fluid without affecting the fluid flow. The working surfaces of the electrode cores 11, 21, and 31 are located at the inner wall 40 of the pipe under test 4, thus enabling accurate detection of the corrosion and scaling state of the inner wall of the pipe under test 4.

[0062] like Figure 2 , Figure 3 As shown, the electrode core 11 of the working electrode 1 in this embodiment of the present invention is cylindrical and is made of the same substrate as the test pipe 4 or made from materials taken from the test pipe 4. The insulating cylinder 10 of the working electrode 1 is made of polytetrafluoroethylene material, but other insulating materials can also be used, and are not limited here.

[0063] When the electrode core 11 is manufactured using material taken from the pipe 4 under test, it includes a working surface 110 exposed inside the pipe 4. The working surface 110 of the electrode core 11 has a corrosion scale layer on the inner wall 40 of the pipe 4 under test. To achieve more accurate detection results, the corrosion scale layer must be kept intact and undamaged during collection and installation. For pipes that have already been laid and used, which have been in use for a period of time and have developed a corrosion scale layer on their inner walls, the material of the pipe itself is used, preserving the corrosion scale layer. This effectively characterizes the electrochemical reaction properties and scale structure characteristics of the actual water supply pipe at the electrode assembly installation location, thereby enabling more accurate detection of the pipe's corrosion status in subsequent testing processes.

[0064] For example, according to the needs of on-site monitoring, the material of the electrode core 11 of the working electrode 1 is selected from the pipe 4 under test. The material cut from the hole of the pipe 4 under test can be used to process it into a columnar electrode core 11, ensuring that the corrosion scale surface of the inner wall of the pipe 4 under test is completely preserved as the electrode working surface 110.

[0065] like Figure 5 As shown, the auxiliary electrode 2 of this embodiment is sheet-shaped and includes a first working surface 211 exposed inside the cavity of the pipe 4 to be tested and a second working surface 212 opposite to the first working surface 211. The front end face of the head 20 of the auxiliary electrode 2 is provided with a recess 23 that extends into the cavity of the pipe 4 to be tested and installs the electrode core 21. The sidewall of the recess 23 is provided with a plurality of connecting grooves 24 along the circumferential direction, connecting the cavity of the pipe 4 to be tested and the recess 23. Water can flow into the second working surface 212 of the auxiliary electrode 2 through the connecting grooves 24, thereby realizing that both sides of the auxiliary electrode 2 work simultaneously.

[0066] In this embodiment, the auxiliary electrode 2 is a circular platinum sheet with the same diameter as the working surface diameter of the working electrode 1. The platinum sheet is parallel or nearly parallel to the water flow direction, and the terminal 22 is connected to the center of the platinum sheet and located on the central axis of the auxiliary electrode 2. The auxiliary electrode 2 is embedded in a recess 23 with a depth ranging from 2mm to 5mm. Multiple connecting grooves 24 along the circumferential direction of the sidewall of the recess 23 are distributed in a fence-like pattern, allowing the water flow in the pipe 4 under test to simultaneously contact the working surfaces on both sides of the platinum sheet.

[0067] like Figure 6 , Figure 7 As shown, the reference electrode 3 of this embodiment has a cylindrical electrode core 31, and the front end face of the head 302 of the insulating cylinder 30 is provided with a receiving hole 303 for accommodating the electrode core 31. The reference electrode 3 of this embodiment uses an Ag / AgCl electrode, and the electrolyte is a saturated KCl solution. The insulating cylinder 30 of the reference electrode 3 is made of polytetrafluoroethylene (PTFE).

[0068] In this embodiment of the invention, the insulating cylinders 10, 20, and 30 of the working electrode 1, auxiliary electrode 2, and reference electrode 3 are all cylindrical structures. The diameters of the electrode cores 11, 21, and 31 are equal, thus ensuring that the areas of the multiple electrode cores 11, 21, and 31 are well-matched, resulting in less surface polarization and smaller errors. The outer diameters of the insulating cylinders 10, 20, and 30 of the working electrode 1, auxiliary electrode 2, and reference electrode 3 are all greater than 1.0 cm and less than 2.0 cm, allowing the electrode assembly to be installed using tools from piping instruments and other equipment.

[0069] The insulating cylinders 10, 20, and 30 are all hollow cylinders or internally stepped cylindrical parts made of polytetrafluoroethylene. The terminals 12, 22, and 32 are made of copper or aluminum, one end of which is connected to the rear end face of the electrode cores 11, 21, and 31, and the other end is exposed and connected to the electrochemical workstation 6 through a wire.

[0070] The test pipe 4 in this embodiment is made of metal without an inner lining. During installation, three or more holes, arranged at equal intervals in the circumferential or axial direction, can be drilled on the test pipe 4 according to the actual burial conditions and on-site installation conditions of the test pipe 3. This allows multiple electrodes of one or more electrode assemblies to be embedded in the test pipe 4. The holes in the test pipe 4 are through holes to ensure that multiple electrodes can contact the water flow inside the test pipe 4. Theoretically, the closer the three electrodes are, the more accurate the measured value. However, the closer the electrodes are, the more difficult it is to process the holes. Therefore, the spacing between adjacent holes is chosen to be less than 1.5 cm, which ensures that the three electrodes are as close as possible while also reducing the difficulty of hole processing. In this embodiment, the multiple holes in the test pipe 4 have the same diameter, and the center-to-center distance between adjacent holes is greater than the hole diameter, by approximately 1 cm. The working electrode 1, auxiliary electrode 2, and reference electrode 3 have their heads 102, 202, and 302, as well as their three holes, machined with matching threads. They are then screwed into the holes on the pipe 4 to be tested. Sealing rings can be added to improve sealing.

[0071] The electrode assembly of this utility model embodiment has various forms of installation on the pipe 4 to be tested. In one exemplary embodiment, such as Figure 8 As shown, the working electrode 1, auxiliary electrode 2, and reference electrode 3 are arranged at intervals along the water flow direction, with the working electrode 1 located between the auxiliary electrode 2 and the reference electrode 3. In another exemplary embodiment, as... Figure 9 As shown, the working electrode 1, auxiliary electrode 2, and reference electrode 3 are arranged at intervals along the circumference of the pipe 4 to be tested, with the working electrode 1 located between the auxiliary electrode 2 and the reference electrode 3. In both examples, the working electrode 1 is positioned between the auxiliary electrode 2 and the reference electrode 3, so that both the auxiliary electrode 2 and the reference electrode 3 can work in conjunction with the working electrode 1.

[0072] In this embodiment of the invention, multiple electrodes of the electrode assembly can be screwed into the holes on the pipe 4 to be tested, with the working surfaces of each electrode in close contact with the inner wall of the pipe 4. Then, using an electrochemical workstation 6, electrochemical signal tests, including polarization curves and AC impedance spectroscopy, can be performed on the electrode assembly. The computer 5 collects electrochemical signals such as corrosion current, corrosion resistance, and AC impedance of each electrode, and analyzes the characteristics of the corrosion process and corrosion products of the working electrode.

[0073] The present invention also provides a method for manufacturing and installing the electrode assembly as described in any of the above embodiments in practical applications, comprising the following operations:

[0074] N1. Using a small machine tool or laser cutting, drill multiple holes in the circumferential or axial direction on the actual metal water supply pipe 4 to be tested.

[0075] N2. Using a tapping machine or a high-precision tap, tap the sides of the electrode housing and the holes in the pipe to be tested to form threads with matching tooth profile, nominal diameter, number of threads, pitch (or lead), and direction of rotation. Machine threads in the through holes of the pipe to be tested (position 4), and machine threads on the outer walls of the heads 102, 202, and 302 of the insulating cylinders 10, 20, and 30. The thread engagement length of the working electrode 1 and the reference electrode 3 matches the hole depth, and the thread engagement length of the auxiliary electrode 2 is the sum of the hole depth and the depth of the recess 23 in the electrode core 21.

[0076] N3. Install the working electrode 1, auxiliary electrode 2, and reference electrode 3 of the electrode assembly in the corresponding holes. If the working electrode 1, auxiliary electrode 2, and reference electrode 3 are installed in the axial direction, then the auxiliary electrode 2, working electrode 1, and reference electrode 3 are installed sequentially along the water flow direction; if the working electrode 1, auxiliary electrode 2, and reference electrode 3 are installed in the circumferential direction, then the working electrode 1 is located between the auxiliary electrode 2 and the reference electrode 3.

[0077] The detection system 100 of this utility model embodiment can be applied to various types of pipes 4 to be tested, and can effectively detect the corrosion status of the pipes 4 to be tested.

[0078] For example, the detection device 100 for monitoring pipeline corrosion status according to this utility model embodiment is installed on a DN100 ductile iron pipeline (9mm wall thickness) that has been passing through the pipeline well and has been in service for 10 years. The specific operation is as follows:

[0079] (1) Fabrication of auxiliary electrode 2. The working surface of electrode core 21 is a circular platinum sheet with a diameter of approximately 8 mm. The platinum sheet is tightly attached to the insulating cylinder 20 and extends into the end face of the pipe to be tested. Terminal 22 is connected to the center of the platinum sheet and is located on the central axis of auxiliary electrode 2. The insulating cylinder 20 is made of polytetrafluoroethylene and has an outer diameter of approximately 14 mm. The end face of the head 202 of the insulating cylinder 20 has a recess 23 with a diameter of approximately 8 mm and a depth of approximately 2 mm. The side wall of the recess 23 has a connecting groove 24, which allows the external aqueous solution to contact the working surfaces on both sides of the platinum sheet simultaneously.

[0080] (2) Fabrication of the reference electrode 3. The reference electrode 3 has a columnar structure. The electrode core 31 of the reference electrode 3 is an Ag / AgCl electrode, and the electrolyte is a saturated KCl solution. The insulating cylinder 30 is made of polytetrafluoroethylene and has an outer diameter of approximately 14 mm.

[0081] (3) Fabrication of working electrode 1. Three holes with a diameter of approximately 12 mm are drilled sequentially in the axial direction on the top of the pipe 4 to be tested using a small hole saw. The distance between the centers of two adjacent holes is approximately 22 mm. A piece of cylindrical pipe wall material drilled by the hole saw is taken, and the surface other than the inner wall with scale is polished to form a cylindrical iron-based material with a diameter of approximately 8 mm, which serves as the electrode core 11. A copper terminal 12 is connected to the center of the cylindrical iron-based material, and the corrosion scale layer on the iron-based material serves as the working surface 110. An insulating cylinder 10 made of polytetrafluoroethylene material is encapsulated on the outside, and a terminal 12 is added to the end to form a cylindrical working electrode 1 with an outer diameter of approximately 14 mm.

[0082] (4) Use a tap to grind internal threads inside the three holes at the top of the pipe 4 to be tested. The thread type can be Rp1 / 4, and the thread engagement length is approximately 9mm. Use a threading machine to grind external threads on the side shells of the working electrode 1, auxiliary electrode 2, and reference electrode 3. The thread type is R1 1 / 4. The thread engagement length of the working electrode 1 and reference electrode 3 is 9mm, and the thread engagement length of the auxiliary electrode 2 is approximately 11mm.

[0083] (5) Following the direction of water flow, screw the auxiliary electrode 2, working electrode 1 and reference electrode 3 into the holes in sequence to complete the installation.

[0084] For example, a detection device 100 for monitoring the corrosion status of a newly laid DN200 ductile iron pipe 4 (with a wall thickness of approximately 11 mm) is installed. The specific operation is as follows:

[0085] (1) Fabrication of auxiliary electrode 2. The working surface of electrode core 21 is a circular platinum sheet with a diameter of approximately 8 mm. The platinum sheet is parallel to and closely attached to the end face of the insulating cylinder 20 that extends into the pipe 4 to be tested. Terminal 22 is connected to the center of the platinum sheet and is located on the central axis of auxiliary electrode 2. The insulating cylinder 20 is made of polytetrafluoroethylene with an outer diameter of approximately 14 mm. The end face of the head 202 of the insulating cylinder 20 that extends into the pipe to be tested has a flat cylindrical recess 23 with a bottom diameter of approximately 8 mm and a depth of approximately 2 mm. The sidewall of the recess 23 has multiple connecting grooves 24 along the circumference. The recess 23 and the connecting grooves 24 are connected, so that the external aqueous solution can simultaneously contact the working surfaces on both sides of the platinum sheet.

[0086] (2) Fabrication of reference electrode 3. The reference electrode is an Ag / AgCl electrode, and the electrolyte is a saturated KCl solution. Reference electrode 3 has a columnar structure, and the insulating cylinder 30 is made of polytetrafluoroethylene with an outer diameter of approximately 14 mm.

[0087] (3) Fabrication of the working electrode 1. Three holes, each approximately 12 mm in diameter, are drilled sequentially around the top of the pipe 4 to be tested using a small hole saw. The center-to-center distance between adjacent holes is approximately 22 mm. A cylindrical piece of ductile iron substrate removed from the holes is cut into a cylindrical iron-based material with a diameter of approximately 8 mm and a height of approximately 10 mm. This material is then ground and polished to form the electrode core 31. A copper terminal 12 is connected to the center of the rear end of the cylindrical iron-based material, with the front end exposed as the working surface 110. An insulating cylindrical body 10 made of polytetrafluoroethylene is encapsulated around the cylindrical iron-based material to form the working electrode 1. The outer diameter of the working electrode 1 is approximately 14 mm.

[0088] (4) Use a tap to machine internal threads on the inside of the three holes at the top of the pipe 4 to be tested. The thread type is Rp1 / 4 and the thread engagement length is 11mm. Use a threading machine to grind external threads on the side shells of the working electrode 1, auxiliary electrode 2 and reference electrode 3. The thread type is R1 1 / 4. The thread engagement length of the working electrode 1 and reference electrode 3 is 11mm, and the thread engagement length of the auxiliary electrode 2 is about 13mm.

[0089] (5) Following the right-hand rotation direction of the water flow, screw the auxiliary electrode 2, working electrode 1 and reference electrode 3 into the hole in sequence to complete the installation.

[0090] For example, at the junction of the main pipeline of the residential area and the municipal pipeline, a detection device 100 for monitoring the corrosion status of the pipelines is installed on both the municipal pipeline and the main pipeline of the residential area. The municipal pipeline is a DN200 ductile iron pipeline to be tested (wall thickness 11mm), and the main pipeline of the residential area is a DN200 galvanized steel pipe (wall thickness 9.5mm). The specific operation is as follows:

[0091] (1) Fabrication of two auxiliary electrodes 2. The working surface of the electrode core 21 is a circular platinum sheet with a diameter of 8 mm. The platinum sheet is closely attached to the front of the insulating cylinder 20, and the terminal 22 is connected to the center of the platinum sheet and located on the central axis of the auxiliary electrode 2. The insulating cylinder 20 is made of polytetrafluoroethylene, and the outer diameter of the insulating cylinder 20 is approximately 14 mm. The front of the head 202 of the insulating cylinder 20 is provided with a flat cylindrical recess 23 with a diameter of approximately 8 mm and a depth of approximately 5 mm. The sidewall of the recess 23 is provided with multiple connecting grooves 24 along the circumference. The recess 23 is connected to the connecting grooves 24, so that the external aqueous solution can contact the working surfaces on both sides of the platinum sheet simultaneously.

[0092] (2) Fabricate two reference electrodes 3. The electrode core 31 of the reference electrode 3 is an Ag / AgCl electrode, and the electrolyte is a saturated KCl solution; the insulating cylinder 30 of the reference electrode 3 is made of polytetrafluoroethylene. The reference electrode 3 has a columnar structure with an outer diameter of approximately 14 mm.

[0093] (3) Fabricate two working electrodes 1. On the top of the main pipe of the community and the municipal pipe, use a small hole saw to drill three holes with a diameter of about 12mm in the circumferential direction, with the center distance between two adjacent holes being about 22mm. The distance between the two rows of holes shall not exceed 20cm.

[0094] For municipal pipelines, a cylindrical ductile iron pipe wall material drilled with a hole saw is taken. Except for the surface with internal scale, all other surfaces are ground and polished to form a cylindrical ductile iron base material with a diameter of 8mm, which serves as the electrode core 11. A copper terminal 12 is connected to the center of the cylindrical ductile iron base material, exposing the corrosion scale layer on the pipe 4 as the working surface. A polytetrafluoroethylene (PTFE) insulating cylinder 10 is then encapsulated externally to form the working electrode 1, with an outer diameter of approximately 14mm. Internal threads are machined on the inner side of three holes at the top of the municipal pipeline 4 using a tap. The thread type is Rp 1 / 4, and the thread engagement length is 11mm. External threads are machined on the side insulating cylinders 10, 20, and 30 of the working electrode 1, auxiliary electrode 2, and reference electrode 3 using a threading machine. The thread type is R1 1 / 4. The thread engagement length of the working electrode 1 and reference electrode 3 is 11mm, and the thread engagement length of the auxiliary electrode 2 is 16mm.

[0095] For the community pipeline, a cylindrical galvanized steel pipe wall material drilled with a hole saw is taken. Except for the surface with internal scale, all other surfaces are ground and polished to form a cylindrical galvanized steel base material with a diameter of approximately 8mm, which serves as the electrode core 11. A copper terminal 12 is connected to the center of the cylindrical galvanized steel base material, exposing the corrosion scale layer on the pipe as the working surface. An insulating cylinder 10 made of polytetrafluoroethylene is then encapsulated on the outside to form a cylindrical working electrode 1, with an outer diameter of approximately 14mm. Internal threads are machined inside the three holes at the top of the pipeline under test using a tap. The thread type is Rp 1 / 4, and the thread engagement length is approximately 9.5mm. External threads are ground on the side shells of the working electrode 1, auxiliary electrode 2, and reference electrode 3 using a threading machine. The thread type is R1 1 / 4; the thread engagement length of the working electrode 1 and reference electrode 3 is approximately 9.5mm, and the thread engagement length of the auxiliary electrode 2 is approximately 14.5mm.

[0096] (4) Following the right-hand rotation of the water flow direction, screw the two sets of auxiliary electrodes 2, working electrodes 1 and reference electrodes 3 into the holes of the municipal pipeline and the main pipeline of the community respectively to complete the installation.

[0097] In the description of this utility model, it should be noted that the terms "upper", "lower", "one side", "the other side", "one end", "the other end", "side", "opposite", "four corners", "periphery", "'mouth' structure", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the structure referred to has a specific orientation, or is constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0098] In the description of the embodiments of this utility model, unless otherwise expressly specified and limited, the terms "connection," "direct connection," "indirect connection," "fixed connection," "installation," and "assembly" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection. The terms "installation," "connection," and "fixed connection" can refer to a direct connection or an indirect connection through an intermediate medium, or they can refer to the internal communication between two components. For those skilled in the art, the specific meaning of the above terms in this utility model can be understood according to the specific circumstances.

[0099] Although the embodiments disclosed in this utility model are as described above, the content described is only for the purpose of facilitating understanding of this utility model and is not intended to limit this utility model. Any person skilled in the art to which this utility model pertains may make any modifications and changes in the form and details of the implementation without departing from the spirit and scope disclosed in this utility model, but the patent protection scope of this utility model shall still be defined by the appended claims.

Claims

1. An electrode assembly, characterized in that, include: The test includes a working electrode, an auxiliary electrode, and a reference electrode, which are configured to be installed on the pipe to be tested and to detect the corrosion and scaling condition of the inner wall of the pipe. The working electrode, auxiliary electrode, and reference electrode all include an insulating cylinder and an electrode core housed within the insulating cylinder; the insulating cylinder includes a tail extending out of the pipe to be tested and a head embedded in the pipe to be tested, and the electrode core protrudes from the front end face of the head and is able to contact the fluid in the pipe to be tested.

2. The electrode assembly according to claim 1, characterized in that: The working surfaces of the electrode cores of the working electrode, auxiliary electrode, and reference electrode are radially expanded and aligned with the direction of the fluid in the pipe to be tested. The working surfaces of the electrode cores of the working electrode, auxiliary electrode, and reference electrode are positioned on the inner wall of the pipe to be tested.

3. The electrode assembly according to claim 1, characterized in that: The heads of the working electrode, auxiliary electrode, and reference electrode are all detachably embedded into the test pipe. The working electrode, auxiliary electrode, and reference electrode all have external threads on their head sidewalls, which can be fitted with the internal threads of the corresponding holes in the pipe to be tested.

4. The electrode assembly according to claim 1, characterized in that: The diameters of the electrode cores of the working electrode and the auxiliary electrode are equal; The outer diameter range of the insulating cylinder of the working electrode, auxiliary electrode and reference electrode is greater than 1.0 cm and less than 2.0 cm.

5. The electrode assembly according to claim 1, characterized in that: The electrode core of the working electrode is cylindrical and is manufactured using the same substrate as the pipe being tested; or, The electrode core of the working electrode is manufactured from material taken from the pipe to be tested. The electrode core of the working electrode includes a working surface exposed inside the pipe to be tested, and the working surface has a corrosion scale layer on the inner wall of the pipe to be tested.

6. The electrode assembly according to claim 1, characterized in that: The electrode core of the auxiliary electrode is circular and includes a first working surface exposed inside the pipe to be tested and a second working surface opposite to the first working surface. The front end face of the auxiliary electrode head is provided with a recess that extends into the inner cavity of the pipe to be tested and is used to install its own electrode core. The side wall of the recess is provided with a plurality of connecting grooves along the circumference, which connect the inner cavity of the pipe to be tested and the recess, so that the fluid in the pipe to be tested flows into the second working surface of the auxiliary electrode through the connecting grooves.

7. The electrode assembly according to claim 1, characterized in that: The reference electrode has a cylindrical electrode core, and the front end face of the reference electrode head is provided with a receiving hole for accommodating its own electrode core.

8. A testing device, characterized in that, include: The electrode assembly as described in any one of claims 1-7 and the detection device connected to the electrode assembly; The detection device includes an electrochemical workstation connected to the electrode assembly and a computer connected to the electrochemical workstation.

9. The testing equipment according to claim 8, characterized in that: It also includes a pipe to be tested, which has multiple holes with a spacing of less than 1.5 cm between adjacent holes; The heads of the working electrode, auxiliary electrode, and reference electrode of the electrode assembly are mounted in the corresponding holes.

10. The detection device according to claim 8, characterized in that: The working electrode, auxiliary electrode, and reference electrode are arranged at intervals along the water flow direction of the pipe under test, and the working electrode is located between the auxiliary electrode and the reference electrode; or The working electrode, auxiliary electrode, and reference electrode are arranged at intervals along the circumference of the pipe under test, and the working electrode is located between the auxiliary electrode and the reference electrode along the circumference of the pipe under test.

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