A device and method for measuring the protective potential of the inner wall of a seawater pipeline based on a zinc plug anode.

Abstract

This invention belongs to the field of seawater pipeline cathodic protection potential measurement technology, and relates to a device and method for measuring the inner wall protection potential of seawater pipelines based on zinc plug anodes. The main structure includes the seawater pipeline under test and the zinc plug anode installed on it, as well as a measurement module connected to both. The measurement module has a built-in trigger, an anode protection circuit, a potential measurement circuit, and a controller. The trigger is connected to the anode protection circuit or the potential measurement circuit through the anode terminal. Under normal operation, the seawater pipeline under test is directly connected to the zinc plug anode, and the zinc plug anode provides cathodic protection for the seawater pipeline under test. When the potential measurement signal is triggered manually or automatically, the measurement module disconnects the electrical connection between the zinc plug anode and the seawater pipeline under test, immediately uses the zinc plug anode as the reference electrode and the seawater pipeline under test as the working electrode, and connects to the potential measurement circuit. After a delay and depolarization, the protection potential value of the seawater pipeline under test is read at a set timing point. After the test is completed, the module is reset.

Description

Technical Field

[0001] This invention belongs to the field of seawater pipeline cathodic protection potential measurement technology, specifically relating to a device and method for measuring the inner wall protection potential of seawater pipelines based on zinc plug anodes. It eliminates the need to drill holes in the seawater pipeline to install reference electrodes, and uses zinc plug anodes to measure the protection potential of seawater pipelines. Background Technology

[0002] Seawater pipelines are a crucial component of engineering facilities such as ships, offshore platforms, and coastal power plants, playing a vital role in ensuring the normal operation of ship propulsion systems, auxiliary machinery, and equipment. Seawater pipeline systems are widely distributed, diverse, and difficult to maintain, and are mostly located in harsh environments. Therefore, corrosion and leaks are common problems, seriously affecting the service safety and performance of ships. Currently, copper alloys are widely used in seawater pipeline systems and equipment to improve their resistance to seawater corrosion. Even so, corrosion problems of equipment and fittings still frequently occur in practical applications, impacting the safety of ships and marine engineering facilities. To address this issue, existing large ships and marine engineering seawater pipeline systems commonly employ sacrificial anodes (such as anti-corrosion zinc plugs) for corrosion protection. For example, Chinese Patent 202410651156.X discloses a rapid-installation sacrificial anode device for marine metal corrosion protection, comprising a sacrificial anode, a mounting base, a signal transmission mechanism, and a centering positioning component mounted on the mounting base. The mounting base has a groove for installing the sacrificial anode; the sacrificial anode is fixed within the groove. The centering positioning component includes a drive push rod, a first limiting rod, a transmission connector, and two limiting clamping components. The first limiting rod and the transmission connector can move vertically under the drive of the drive push rod. The two limiting clamping components are respectively located at both ends of the transmission connector. The clamping ends of the two limiting clamping components can move horizontally towards each other under the drive of the transmission connector. A clamping space for clamping the protected cathode is formed between the first limiting rod and the clamping ends of the two limiting clamping components. The signal transmission mechanism is located within the sacrificial anode for real-time, remote feedback. To monitor the loss of the sacrificial anode, a mounting base is provided with a mounting groove. An inner nested tube is embedded in the mounting groove. Both ends of the inner nested tube are fixed to the two ends of the fixed base. The inner nested tube and the inner wall of the mounting groove are spaced apart, forming a mounting area for installing the centering positioning component. The inner nested tube has a clearance groove that cooperates with the clamping end of the centering positioning component. The clamping end extends into the inner cavity of the inner nested tube from the clearance groove. The positioning clamping mechanism also includes multiple positioning fastening structures provided on the mounting base. The positioning fastening structure includes a rotating handle, a connecting rod, and an anti-slip sleeve. The connecting rod is threaded to the corresponding connecting sleeve, and its bottom penetrates the outer wall of the connecting sleeve and extends into the inner cavity of the connecting sleeve. The anti-slip sleeve is provided at the inner end of the connecting rod. The signal transmission mechanism includes a signal circuit, an information processing module, and a signal transmission module. The information processing module is used to analyze the current changes in the signal circuit and determine the remaining amount of the sacrificial anode. The signal transmission module transmits the information on the remaining amount of the sacrificial anode from the information processing module to the onshore monitoring device.Chinese Patent 202420014336.2 discloses an aluminum alloy sacrificial anode protection device for a ship hull, comprising a ship hull; two side plates fixed on the ship hull, each side plate having a groove, and a first slider disposed inside the groove, the first slider being slidably connected to the groove; a bottom plate disposed between the side plates, one side of the bottom plate being connected to the ship hull, and an anode body disposed on the side of the bottom plate away from the ship hull, both ends of the anode body being connected to screws, each screw penetrating the first slider, and a nut disposed at the end of the screw away from the anode body, the nut side being in contact with the first slider; two clamping plates fixed on the side of the bottom plate away from the ship hull, one side of each clamping plate being in contact with the anode body, and the side plates away from the ship hull being rotatably connected to... A lead screw is connected to a pressure plate. The side of the pressure plate away from the lead screw is in contact with a clamping plate. Several elastic components are provided on the side of the hull near the bottom plate. The two ends of the elastic components are connected to the hull and the bottom plate, respectively. A second slider is fixed on both sides of the first slider. T-slots are machined on both sides of the slide groove. The second slider is slidably connected to the T-slots. A groove is machined on the side of the clamping plate away from the bottom plate. The groove is in contact with the lead screw. The cross-section of the pressure plate is an inverted "L" shape. A damper is provided inside the elastic component. The two ends of the damper are connected to the hull and the bottom plate, respectively. A guide rod is provided on one side of the lead screw. A turntable is fixed to the guide rod and the end of the lead screw away from the side plate. The pressure plate is slidably connected to the guide rod, and one end of the guide rod is fixed to the pressure plate. Chinese Patent 202323537324.2 discloses an embedded sacrificial anode for a ship's hull, comprising a hull; a groove is formed on the hull, and two lugs are fixed to one side of the hull. An electric rotating plate is rotatably connected to the side of the lugs away from the hull, and the electric rotating plate corresponds to the groove. An electric telescopic rod is installed inside the groove, and a support is fixed to one end of the electric telescopic rod. An anode body is disposed on the side of the support away from the electric telescopic rod, and several base plates are fixed to the side of the support away from the anode body. A first elastic component is fixedly connected to the side of each base plate near the anode body, and the first elastic component penetrates the support. The end of the first elastic component away from the base plate is fixed to the anode body. The groove has grooves on both sides of its inner wall, and guide rods are fixed inside each groove. Slider blocks are mounted on the guide rods. A second elastic component is fixed to the side of the slider closest to the anode body. The end of the second elastic component away from the slider is fixed to the anode body. The side of the anode body away from the groove is machined into an arc surface. One side of the electric rotating plate is in contact with the anode body, and the rotation angle of the electric rotating plate is 90°. Grooves are machined on both sides of the anode body, and these grooves are fixed to the second elastic components. Dampers are installed inside both the first and second elastic components, and one end of each damper is fixed to the anode body. The sliders are slidably connected to the guide rods, and the sliders correspond to the sides of the anode body. This method effectively inhibits corrosion in seawater pipeline systems. However, due to the small internal space of seawater pipelines and the limited anode sizes that can be installed, the service life of zinc plug anodes is relatively short. At the end of the zinc plug anode's service life, seawater pipelines still face insufficient protection and the risk of corrosion leakage.Because seawater pipeline systems are closed structures, it's impossible to directly observe the consumption and service life of zinc plug anodes. To assess the protective effect on the inner wall of seawater pipelines, it's often necessary to drill holes in the pipeline to install reference electrodes and measure the protection potential. Commonly used reference electrodes include Ag / AgCl, Cu / CuSO4, and high-purity zinc electrodes. Considering the elongated structure of seawater pipelines, which can reach hundreds of meters in length, a large number of reference electrodes are required for potential testing, significantly increasing the workload. Furthermore, increasing the number of holes also exacerbates safety risks associated with seawater pipelines. Therefore, currently, seawater pipelines do not have reference electrodes installed for protection potential monitoring, making it difficult to accurately obtain the actual protective effect on the inner wall of the pipeline. Therefore, this paper proposes a device and method for measuring the protection potential of the inner wall of seawater pipelines. This method utilizes zinc plug anodes to measure the protection potential of seawater pipelines, allowing the zinc plug anodes to both perform cathodic protection and measure the protection potential, thus resolving the structural and safety risks associated with drilling holes in seawater pipelines to install reference electrodes. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of existing technologies and to develop and design a device and method for measuring the protection potential of the inner wall of seawater pipelines based on zinc plug anodes. The invention utilizes the reference electrode properties of high-purity zinc and employs a triggered instantaneous circuit breaking and delayed recording method to measure the protection potential of seawater pipelines.

[0004] To achieve the above objectives, the present invention relates to a seawater pipeline inner wall protection potential measuring device based on zinc plug anode. The main structure includes the seawater pipeline to be measured and the zinc plug anode installed on it, as well as a measuring module connected to the two respectively. The measuring module has a built-in trigger, an anode protection circuit, a potential measuring circuit and a controller. The trigger is connected to the anode protection circuit or the potential measuring circuit through the anode terminal.

[0005] The seawater pipeline under test is connected to the measurement module via a pipeline cable, and the zinc plug anode is connected to the measurement module via an anode cable.

[0006] The measurement module also contains a potentiometer. The pipeline cable is connected to the anode protection circuit and the potential measurement circuit. The anode cable is connected to the anode protection circuit or the potential measurement circuit respectively through the trigger. The controller communicates with the trigger and the potentiometer set on the potential measurement circuit to control the potential measurement operation.

[0007] The zinc plug anode involved in this invention is made of high-purity zinc material that meets the standard requirements for zinc alloy sacrificial anodes. The specifications are selected based on the pipe diameter of the seawater pipeline to be tested, with reference to the zinc plug anode design standard.

[0008] Both conduit cables and anode cables are single-core or multi-core shielded cables with insulated sheaths, with a minimum diameter of 1mm. 2 ;

[0009] The measurement module is encapsulated as a whole. The trigger controls the connection between the anode terminal and the cathodic protection circuit and the potential measurement circuit. It disconnects and connects according to the instructions issued by the controller or manually input, and feeds back the switching time to the controller. The potentiometer is used to test the potential value between the seawater pipeline under test and the zinc plug anode. The input impedance is not less than 10MΩ, the response time is not more than 1ms, and the potential measurement accuracy is not more than ±1μV. The controller has the functions of setting the measurement time, timing, storing and displaying, recording the potential data measured by the potentiometer in real time, and displaying and storing it.

[0010] This invention relates to a method for measuring the protective potential of the inner wall of a seawater pipeline based on a zinc plug anode. Utilizing the reference electrode properties of high-purity zinc, the method employs a triggered instantaneous circuit breaking and delayed recording approach to measure the protective potential of the seawater pipeline. The function of the zinc plug anode 2 can be switched between cathodic protection and potential measurement via automatic or manual triggering. The specific implementation steps of the measurement method are as follows:

[0011] (a) Installation

[0012] The zinc plug anode is installed on the seawater pipeline to be tested using an insulated installation method, and the seawater pipeline to be tested and the zinc plug anode are connected to the measurement module through pipeline cables and anode cables, respectively.

[0013] The zinc plug anode is installed by an insulating screw sleeve or encapsulated with insulating material before being installed on the seawater pipeline to be tested. After installation, the dry insulation resistance between the seawater pipeline to be tested and the zinc plug anode should not be less than 1MΩ.

[0014] Pipeline cables and anode cables use welding or screw connections to ensure good contact, and the connection points are sealed with insulating resin.

[0015] The measurement module is either directly fixed to the seawater pipeline to be measured, or placed near the seawater pipeline to be measured.

[0016] (ii) Cathodic protection

[0017] During operation, the pipeline cable and anode cable are connected to the cathodic protection circuit, and the seawater pipeline under test is directly electrically connected to the zinc plug anode, which plays a cathodic protection role.

[0018] The main function of the zinc plug anode during normal service is to provide cathodic protection for the seawater pipeline under test. In order to ensure that the seawater pipeline under test reaches a stable protection state, the zinc plug anode should be run continuously for more than 24 hours after initial installation, because the protection potential value measured within 24 hours is insufficient to accurately reflect the actual protection effect of the seawater pipeline under test.

[0019] (III) Potential Measurement

[0020] During measurement, a signal is manually triggered or the controller automatically sends a signal periodically / irregularly according to the test requirements to disconnect the connection between the seawater pipeline under test and the zinc plug anode, that is, to disconnect the connection between the anode terminal and the cathodic protection circuit, and connect the anode terminal to the potential measurement circuit.

[0021] When the signal is manually triggered, the trigger will feed back the trigger time to the controller, and at the same time immediately disconnect the electrical connection between the zinc plug anode and the seawater pipeline under test, and switch the anode terminal of the zinc plug anode to the potential measurement circuit.

[0022] When an automatic trigger signal is received, the controller automatically records the trigger time and controls the trigger to switch the wiring.

[0023] (iv) Depolarization

[0024] Based on the depolarization behavior of the seawater pipeline under test and the zinc plug anode under service conditions, the depolarization time is determined, and the protection potential value of the seawater pipeline under test is read and recorded at the time point.

[0025] For the seawater pipeline under specific operating conditions, a depolarization test is used to determine the appropriate time point for delayed testing. The depolarization behavior of the seawater pipeline under test and the zinc plug anode are tested simultaneously. When the residual polarization degree of the zinc plug anode (the difference between polarization potential and natural potential) is equivalent to the depolarization degree of the seawater pipeline under test (the difference between polarization potential and the protection potential before depolarization), the potential value of the seawater pipeline under test measured by the zinc plug anode is consistent with the actual protection potential value of the seawater pipeline under test before depolarization (relative to the zinc reference electrode). This time point is taken as the potential measurement time of the seawater pipeline under test. The controller collects the reading of the potentiometer at this time as the protection potential value of the seawater pipeline under test.

[0026] For different seawater pipeline systems under test, the depolarization behavior of the seawater pipeline and zinc plug anode is related to seawater flow velocity, temperature, pipe diameter, etc. In addition, the material and surface condition (presence or absence of sediment, etc.) of the seawater pipeline under test have an impact on the depolarization effect: under the condition of still seawater, the depolarization time is 1-4s; under the condition of flowing seawater, the depolarization time decreases with the increase of flow velocity, and the depolarization time is 0.5-2s when the flow velocity is 1-3m / s.

[0027] (v) Reset

[0028] After the measurement is completed, the seawater pipeline under test is reconnected to the zinc plug anode, and the zinc plug anode continues to provide cathodic protection for the seawater pipeline under test.

[0029] After the potential test of the seawater pipeline under test is completed, the controller issues a new command to control the trigger to disconnect the anode terminal of the zinc plug anode from the potential measurement circuit and reconnect it to the cathodic protection circuit to continue to provide cathodic protection for the seawater pipeline under test until the next potential test command is triggered.

[0030] To ensure that the seawater pipeline under test is kept in a fully protected state, the interval between two adjacent potential measurements of the seawater pipeline under test should be more than 1 hour.

[0031] Compared with existing technologies, this invention, under normal operation, directly connects the seawater pipeline under test to the zinc plug anode, which provides cathodic protection. When a potential measurement signal is manually or automatically triggered, the measurement module disconnects the zinc plug anode from the seawater pipeline under test, immediately using the zinc plug anode as the reference electrode and the seawater pipeline under test as the working electrode, and connects to the potential measurement circuit. After a delay and depolarization, the protection potential value of the seawater pipeline under test is read at a set time point. After the test, the zinc plug anode is directly connected to the seawater pipeline under test again, and the zinc plug anode resumes its cathodic protection function until the next potential measurement signal is triggered. Its structure is simple, which can utilize the cathodic protection function of the zinc plug anode and directly use the zinc plug anode to accurately measure the protection potential of the inner wall of the seawater pipeline under test, thereby avoiding the structural damage and safety risks caused by drilling holes in the seawater pipeline under test to install a reference electrode. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the main structure of the seawater pipeline inner wall protection potential measuring device based on zinc plug anode, which is involved in this invention.

[0033] Figure 2 This is a schematic diagram of the potential change of the seawater pipeline 1 and zinc plug anode 2 to be tested according to the present invention. Detailed Implementation

[0034] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0035] Example 1:

[0036] The main structure of the seawater pipeline inner wall protection potential measuring device based on zinc plug anode involved in this embodiment is as follows: Figure 1 As shown, it includes a seawater pipeline to be tested 1, a zinc plug anode 2, a pipeline cable 3, an anode cable 4, and a measurement module 5. The seawater pipeline to be tested 1 is equipped with a zinc plug anode 2. The seawater pipeline to be tested 1 and the zinc plug anode 2 are connected to the measurement module 5 through the pipeline cable 3 and the anode cable 4, respectively.

[0037] The measurement module 5 includes a trigger 6, an anode terminal 7, an anode protection circuit 8, a potential measurement circuit 9, a potentiometer 10, and a controller 11. The trigger 6 is connected to the anode protection circuit 8 or the potential measurement circuit 9 through the anode terminal 7, and a potentiometer 10 is installed on the potential measurement circuit 9.

[0038] The pipeline cable 3 is connected to the anode protection circuit 8 and the potential measurement circuit 9;

[0039] Anode cable 4 connects trigger 6, controller 11 and potentiometer 10 in series.

[0040] The specific process of the seawater pipeline inner wall protection potential measurement method based on zinc plug anode involved in this embodiment is as follows:

[0041] The seawater pipeline 1 to be tested is installed together with the zinc plug anode 2 using an insulated installation method to ensure complete insulation between the two.

[0042] The seawater pipeline 1 to be tested is connected to the cathodic protection circuit 8 and potential measurement circuit 9 set in the measurement module 5 via the pipeline cable 3, and the zinc plug anode 2 is connected to the trigger 6 in the measurement module 5 via the anode cable 4.

[0043] During normal operation, the anode terminal 7 is connected to the cathodic protection circuit 8. At this time, the seawater pipeline 1 under test is directly connected to the zinc plug anode 2, and the zinc plug anode 2 provides cathodic protection for the seawater pipeline 1 under test.

[0044] When measuring the protection potential, the controller 11 sends a signal to control the trigger 6 to disconnect the connection between the anode terminal 7 and the cathodic protection circuit 8, and immediately switch the connection between the anode terminal 7 and the potential measurement circuit 9. This time point is recorded as the trigger point t0.

[0045] After the potential measurement circuit 9 is turned on, the zinc plug anode 2 acts as a reference electrode, the potentiometer 10 measures the potential difference between the seawater pipeline 1 under test and the zinc plug anode 2, and the controller 11 reads the measured value of the potentiometer 10 at a preset time point t' based on the depolarization effect between the seawater pipeline 1 under test and the zinc plug anode 2, and records it as the protection potential value of the seawater pipeline 1 under test.

[0046] After the measurement is completed, the controller 11 sends a signal again to control the trigger 6 to disconnect the connection between the anode terminal 7 and the potential measurement circuit 9, and switch the anode terminal 7 back to the connection with the cathodic protection circuit 8, so that the zinc plug anode 2 can continue to play the role of cathodic protection.

[0047] During the measurement of the protection potential, the electrical connection between the seawater pipeline 1 under test and the zinc plug anode 2 is disconnected according to the trigger signal, and the potential measurement circuit 9 is immediately connected. However, because the zinc plug anode 2 is polarized during cathodic protection, its potential deviates from its natural potential. At this time, it cannot be directly used as a reference electrode for protection potential measurement and needs to wait for the zinc plug anode 2 to depolarize. However, the time required for the zinc plug anode 2 to reach complete depolarization and restore its potential to its natural potential is relatively long. During this period, the seawater pipeline 1 under test loses the protection of the zinc plug anode 2 and undergoes depolarization simultaneously, causing its potential to deviate from the original protection potential. Therefore, the potential of the seawater pipeline 1 under test measured by the zinc plug anode 2 does not match the actual protection potential. Therefore, based on the depolarization effect of the seawater pipeline 1 under test and the zinc plug anode 2, it is necessary to select an appropriate measurement time so that both the seawater pipeline 1 under test and the zinc plug anode 2 are depolarized. When the residual polarization of the zinc plug anode 2 is comparable to the depolarization of the seawater pipeline 1 under test, the potential of the seawater pipeline 1 under test measured by the zinc plug anode 2 is consistent with the actual protection potential. Selecting this time point can accurately measure the potential of the seawater pipeline 1 under test.

[0048] Example 2:

[0049] In practical use, the seawater pipeline inner wall protection potential measuring device based on zinc plug anode involved in this embodiment is as follows:

[0050] First, a copper alloy seawater pipeline with a diameter of DN50 and a length of 3m is taken as the seawater pipeline to be tested 1. The flow velocity of the normal temperature seawater in the seawater pipeline to be tested 1m / s.

[0051] Secondly, a zinc plug anode 2 with a specification of Φ16×24mm is installed in the middle of the seawater pipeline 1 to be tested through a nylon threaded sleeve. A pipeline cable 3 is connected to the seawater pipeline 1 to be tested near the zinc plug anode 2, and an anode cable 4 is connected to the top of the zinc plug anode 2.

[0052] In order to test the depolarization effect of the seawater pipeline 1 and zinc plug anode 2 and to verify the potential measurement results of the seawater pipeline 1, a high-purity zinc reference electrode was installed by drilling a hole opposite the zinc plug anode 2.

[0053] The zinc plug anode 2 provides cathodic protection for the seawater pipeline 1 under test. After continuous operation for more than 24 hours, the seawater pipeline 1 under test and the zinc plug anode 2 reach a stable polarization state.

[0054] Then, a depolarization test was performed on the seawater pipeline 1 and the zinc plug anode 2. At a certain time point (t0), the connection between the seawater pipeline 1 and the zinc plug anode 2 was disconnected, and the potential changes of the seawater pipeline 1 and the zinc plug anode 2 were immediately and continuously recorded synchronously using a dual-channel electrochemical testing system. The results are as follows: Figure 2As shown, before the seawater pipeline 1 under test is disconnected from the zinc plug anode 2, the protection potential of the seawater pipeline 1 under test is 0.44V (vs. Zn, the same below). After disconnection, both the seawater pipeline 1 and the zinc plug anode 2 under test undergo depolarization. The potential of the seawater pipeline 1 under test shifts positively, while the potential of the zinc plug anode 2 shifts negatively. Since the zinc plug anode 2 is relatively small in size and has a large degree of polarization, the depolarization process is faster. However, the seawater pipeline 1 under test has a larger area, so the depolarization is relatively slow. After about 1.4s, both the seawater pipeline 1 and the zinc plug anode 2 under test have undergone a certain degree of depolarization. At this time, the zinc plug anode 2 is used as the reference electrode, and the potential of the seawater pipeline 1 under test is measured to be equivalent to the actual protection potential of the seawater pipeline 1 under test before depolarization (0.44V). Therefore, t'=1.4s is selected as the measurement point for the protection potential of the seawater pipeline 1 under test.

[0055] Finally, the seawater pipeline 1 and the zinc plug anode 2 were connected to the measurement module 5. The measurement module 5 was set to record the potential value 1.4 seconds after triggering. When measuring the potential, the measurement module 5 automatically or manually triggers the measurement signal at regular intervals. 1.4 seconds after each triggering of the measurement signal, the measurement module 5 automatically records the protection potential value of the seawater pipeline 1. At the same time, the protection potential of the seawater pipeline 1 is measured synchronously using a high-purity zinc reference electrode. The measurement results are shown in Table 1.

[0056] Serial Number Zinc plug anode measurement results Reference electrode measurement results relative error 1 0.452 0.441 2.49% 2 0.463 0.445 4.04% 3 0.449 0.428 4.91%

[0057] It can be seen that the potential of the seawater pipeline 1 under test measured by the zinc plug anode 2 is basically consistent with the potential value of the seawater pipeline 1 under test measured by the high-purity zinc reference electrode, with a relative error of no more than 5%. This indicates that the zinc plug anode 2 can accurately evaluate the protection effect of the seawater pipeline 1 under test.

Claims

1. A device for measuring the protective potential of the inner wall of a seawater pipeline based on a zinc plug anode, characterized in that, The main structure includes the seawater pipeline under test and the zinc plug anode installed on it, as well as a measurement module connected to both. The measurement module contains a trigger, an anode protection circuit, a potential measurement circuit, and a controller. The trigger connects to either the anode protection circuit or the potential measurement circuit via the anode terminal. The measurement module also contains a potentiometer. The pipeline cable connects to both the anode protection circuit and the potential measurement circuit. The anode cable, controlled by the trigger, connects to either the anode protection circuit or the potential measurement circuit. The controller communicates with the trigger and the potentiometer installed on the potential measurement circuit. Utilizing the reference electrode properties of high-purity zinc, the protection potential of the seawater pipeline is measured using a trigger-based instantaneous circuit breaking and delayed recording method. The zinc plug anode switches between cathodic protection and potential measurement via automatic or manual triggering. Both the pipeline cable and the anode cable are single-core or multi-core shielded cables with insulated sheaths, with a minimum diameter of 1mm. 2 The measurement module is encapsulated as a whole. The trigger controls the connection between the anode terminal and the cathodic protection circuit and the potential measurement circuit. It disconnects and connects according to the instructions issued by the controller or manually input, and feeds back the switching time to the controller. The potentiometer measures the potential value between the seawater pipeline under test and the zinc plug anode. The input impedance is not less than 10MΩ, the response time is not more than 1ms, and the potential measurement accuracy is not more than ±1μV. The controller has the functions of setting the measurement time, timing, storing and displaying, and records the potential data measured by the potentiometer in real time, and displays and stores it.

2. The seawater pipeline inner wall protection potential measuring device based on zinc plug anode according to claim 1, characterized in that, The specific measurement steps are as follows: (a) Installation The zinc plug anode is installed on the seawater pipeline to be tested, and the seawater pipeline to be tested and the zinc plug anode are connected to the measurement module through the pipeline cable and the anode cable, respectively. (ii) Cathodic protection During operation, the pipeline cable and anode cable are connected to the cathodic protection circuit, and the seawater pipeline under test is directly electrically connected to the zinc plug anode, which provides cathodic protection. (III) Potential Measurement During measurement, a signal is manually triggered or the controller automatically sends a signal periodically / irregularly according to the test requirements to disconnect the connection between the seawater pipeline under test and the zinc plug anode, and connect the anode terminal to the potential measurement circuit. (iv) Depolarization Based on the depolarization behavior of the seawater pipeline under test and the zinc plug anode under service conditions, the depolarization time is determined, and the protection potential value of the seawater pipeline under test is read and recorded at the time point.

3. The seawater pipeline inner wall protection potential measuring device based on zinc plug anode according to claim 2, characterized in that, In step (1), the zinc plug anode is installed by an insulating screw sleeve, or encapsulated with insulating material before being installed on the seawater pipeline to be tested. After installation, the dry insulation resistance between the seawater pipeline to be tested and the zinc plug anode should not be less than 1MΩ. Pipeline cables and anode cables are connected by welding or screws, and the connection points are sealed with insulating resin. The measurement module is either directly fixed to the seawater pipeline to be measured, or placed near the seawater pipeline to be measured.

4. The seawater pipeline inner wall protection potential measuring device based on zinc plug anode according to claim 2, characterized in that, In step (ii), the main function of the zinc plug anode during normal service is to provide cathodic protection for the seawater pipeline under test. After the zinc plug anode is initially installed, it should run continuously for more than 24 hours.

5. The seawater pipeline inner wall protection potential measuring device based on zinc plug anode according to claim 2, characterized in that, In step (3), when the signal is manually triggered, the trigger will feed back the trigger time to the controller, and at the same time immediately disconnect the electrical connection between the zinc plug anode and the seawater pipeline under test, and switch the anode terminal of the zinc plug anode to the potential measurement circuit. When an automatic trigger signal is triggered, the controller automatically records the trigger time and controls the trigger to switch the wiring.

6. The seawater pipeline inner wall protection potential measuring device based on zinc plug anode according to claim 2, characterized in that, In step (iv), a depolarization test is used to determine a suitable time delay test point. The depolarization behavior of the seawater pipeline under test and the zinc plug anode are tested simultaneously. When the residual polarization of the zinc plug anode is comparable to the depolarization of the seawater pipeline under test, the potential value of the seawater pipeline under test measured by the zinc plug anode is consistent with the actual protection potential value of the seawater pipeline under test before depolarization. This time point is taken as the potential measurement time of the seawater pipeline under test. The controller collects the reading of the potentiometer at this time as the protection potential value of the seawater pipeline under test.

7. The seawater pipeline inner wall protection potential measuring device based on zinc plug anode according to claim 2, characterized in that, After the measurement is completed, the seawater pipeline under test is reconnected to the zinc plug anode, and the zinc plug anode continues to provide cathodic protection for the seawater pipeline under test; the potential measurement interval between two adjacent seawater pipelines under test is more than 1 hour.

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