Seawater pipeline dissimilar metal contact current test experimental device and experimental method

Abstract

The invention relates to the technical field of dissimilar metal contact current testing experiments, in particular to a seawater pipeline dissimilar metal contact current testing experiment device and an experiment method.The seawater pipeline dissimilar metal contact current testing experiment device comprises a testing mechanism and a circulating mechanism, and the testing mechanism comprises a testing level pipe, a wire, a zero-resistance galvanometer and a testing box; the circulating mechanism comprises a circulating pipeline, a variable-frequency corrosion-resistant pump, a circulating water tank, a valve assembly, an electromagnetic flowmeter and a testing box, the variable-frequency corrosion-resistant pump and the electromagnetic flowmeter are connected to the circulating pipeline in series, the two ends of the circulating pipeline are installed on the circulating water tank, the testing level pipe is placed in the testing box, and the zero-resistance galvanometer is connected with the testing level pipe through a wire; the valve assembly controls the seawater flow in the circulating water tank and the circulating pipeline. A tubular structure and a pipeline system experiment are adopted, so that the structure-level dissimilar metal contact current test of a seawater pipeline under a simulated working condition is realized, and the dissimilar metal contact corrosion experiment capability is effectively improved.

Description

Technical Field

[0001] The present invention relates to the technical field of dissimilar metal contact current test experiments, and particularly relates to a test experiment device and method for dissimilar metal contact current in a seawater pipeline. Background Art

[0002] As a part of the ship's power system, the performance of the ship's seawater pipeline system directly affects the exertion of the ship's kinetic energy. Therefore, the corrosion resistance and reliability of the seawater pipeline system become one of the important factors to ensure the safe operation of the ship and improve the in-service rate. Due to the characteristics of numerous materials, complex structures, and variable working conditions in the seawater pipeline system, the problem of seawater pipeline failure caused by dissimilar metal contact has occurred frequently for a long time. However, there is a lack of experimental devices and methods for evaluating the corrosion degree of dissimilar metal contact at the structural level. Therefore, the problem of seawater pipeline failure in ships caused by dissimilar metal contact has never been effectively controlled, and the treatment is in a passive state. Currently, most of the test experiments on dissimilar metal contact current are based on coupon-type material-level experiments, and the environmental factors are single, so it is impossible to test engineering pipelines. In addition, the magnitude and influence range of the contact current are not only related to the material itself, but to a greater extent affected by the working conditions and structure. Therefore, inventing a test device and method for measuring the contact current density using the pipeline structure under pipeline working conditions is of great significance for guiding engineering design and protection. At present, no literature and patents on experimental devices and methods that can simulate the structure and working conditions of actual ship pipelines have been retrieved.

[0003] Both GB / T 15748-1995 "Test Method for Galvanic Corrosion of Marine Metallic Materials" and HB5374-1987 "Method for Determining Galvanic Current between Different Metals" are test methods for measuring dissimilar metal contact current in the laboratory using plate-shaped coupon specimens. Their advantages are convenient operation and easy implementation, but they are only applicable to evaluating the performance of the material itself and cannot reflect the influence of the structure and working conditions on the current.

[0004] CN200910238567.1 discloses a galvanic corrosion test device for experimental research on galvanic corrosion between any two different metal materials in a solution medium containing CO2 / H2S. Its advantage is that it improves the situation of complex production of working electrodes, inaccurate anode-cathode area ratio, and unstable experiments. Its disadvantage is that it still uses plate-shaped specimens and cannot realize the test of pipeline samples.

[0005] CN202110488328.2 discloses a multi-condition galvanic corrosion test device, which can control environmental factors such as oxygen content and temperature, and adopts a plug-in specimen installation to achieve a test method for accurately controlling different spacings. Its method still uses plate-shaped specimens and cannot realize the test of tubular structures.

[0006] In summary, there is no literature or patent disclosure on an experimental device and method for testing the galvanic current of dissimilar metals that can simulate the pipeline structure and working conditions of a real ship. Summary of the Invention

[0007] Aiming at the problems existing in the prior art, the present invention provides an experimental device and method for testing the galvanic current of dissimilar metals in a seawater pipeline, which is used to simulate the operating conditions of a seawater pipeline, realize the laboratory evaluation of the magnitude and influence distance of the galvanic current of dissimilar metals in the seawater pipeline structure level, fill the gap in the experimental device and method for testing the galvanic current of dissimilar metals in the pipeline structure level, and improve the experimental ability of evaluating the corrosion of dissimilar metal contacts.

[0008] To achieve the above object, the technical solution adopted by the present invention is: an experimental device for testing the galvanic current of dissimilar metals in a seawater pipeline, including a test mechanism and a circulation mechanism. The test mechanism includes a test-level pipe, a wire, a zero-resistance ammeter, and a test box. The circulation mechanism includes a circulation pipeline, a frequency-converting corrosion-resistant pump, a circulation water tank, a valve assembly, and an electromagnetic flowmeter. The test box, the frequency-converting corrosion-resistant pump, and the electromagnetic flowmeter are connected in series on the circulation pipeline. Both ends of the circulation pipeline are installed on the circulation water tank. The test-level pipe is placed in the test box. The zero-resistance ammeter is connected to the test-level pipe through a wire. The valve assembly controls the seawater flow in the circulation water tank and the circulation pipeline.

[0009] For the above experimental device for testing the galvanic current of dissimilar metals in a seawater pipeline, the test-level pipe includes a cathode pipe section, an anode pipe section, a fastener, and an insulating flange. The fastener penetrates through the cathode pipe section and the anode pipe section. The insulating flange is installed at both ends of the fastener to clamp the cathode pipe section and the anode pipe section in the middle.

[0010] For the above experimental device for testing the galvanic current of dissimilar metals in a seawater pipeline, the cathode pipe section includes at least two high-potential metal alloy rings and insulating sealing gaskets. The insulating sealing gaskets are arranged between two adjacent high-potential metal alloy rings. Each high-potential metal alloy ring is individually connected to the zero-resistance ammeter through a wire. The anode pipe section includes at least two low-potential metal alloy rings and insulating sealing gaskets. Insulating sealing gaskets are arranged between two adjacent low-potential metal alloy rings. Each low-potential metal alloy ring is individually connected to the zero-resistance ammeter through a wire.

[0011] For the above experimental device for testing the galvanic current of dissimilar metals in a seawater pipeline, it further includes a temperature control switch, an environmental factor sensor, and a stirrer. The temperature control switch and the environmental factor sensor are arranged in the circulation water tank. The temperature control switch adjusts the temperature of the seawater in the circulation water tank to maintain a constant temperature state. The stirring end of the stirrer extends into the circulation water tank.

[0012] The above-mentioned experimental device for testing the contact current of dissimilar metals in a seawater pipeline. The circulation water tank includes a water inlet, a water outlet, a circulation outlet, and a circulation inlet. The circulation outlet and the water outlet are arranged at the lower part of the circulation water tank, and the circulation inlet and the water inlet are arranged at the upper part of the circulation water tank.

[0013] The above-mentioned experimental device for testing the contact current of dissimilar metals in a seawater pipeline. The valve assembly includes an inlet valve, an outlet valve, a drain valve, and at least one control valve. The control valve is connected in series on the circulation pipeline. The inlet valve is arranged at the water inlet of the circulation water tank, and the outlet valve is arranged at the water outlet of the circulation water tank. One of the control valves is arranged between the circulation outlet and the frequency conversion corrosion-resistant pump. A drain port is arranged on the circulation pipeline between the frequency conversion corrosion-resistant pump and the circulation outlet, and the drain valve is arranged at the drain port.

[0014] An experimental method for an experimental device for testing the contact current of dissimilar metals in a seawater pipeline includes the following steps: Step 1: Connect the frequency conversion corrosion-resistant pump, the circulation water tank, the control valve, the electromagnetic flowmeter, and the test water tank in series with a circulation water pipe. Place the stirring end of the stirrer in the seawater in the circulation water tank. Set the circulation water tank to a constant temperature state, and install environmental factor sensors. Step 2: Select the metal ring materials for the cathode pipe section and the anode pipe section according to the experimental requirements. Use insulating sealing gaskets to separate the metal rings of the cathode pipe section and the anode pipe section one by one. Clamp the cathode pipe section and the anode pipe section with fasteners and non-metallic insulating flanges. Each metal ring is connected to a zero-resistance ammeter through a rubber sleeve wire. Place the cathode pipe section and the anode pipe section into the test water tank at the same time. Step 3: After filling with seawater, close the inlet valve, the outlet valve, and the drain valve. Open the control valve. Set the seawater temperature to a constant temperature state and the flow rate to 2 - 4 m / s. Each component starts to operate according to the set operating parameters. Step 4: Set the time period for measuring the coupled current density. Measure the coupled current density between the dissimilar metals of the cathode pipe section and the anode pipe section with a zero-resistance ammeter according to the time period. Measure once a day after 24 hours. Stop measuring when the magnitude of the coupled current density does not change significantly with time.

[0015] The experimental method for the above-mentioned experimental device for testing the contact current of dissimilar metals in a seawater pipeline includes, in the said Step 4: Fix the cathode area of the cathode pipe section. Gradually increase the number of anode pipe sections in sequence from the coupling position. Respectively test the current magnitude when the cathode is coupled with different numbers of anode pipe sections. Analyze the variation law of the coupled current density with the coupling distance, and evaluate the influence distance of the coupled current on the anode pipe section. Fix the anode area of the fixed anode tube segment, gradually increase the number of cathode tube segments in sequence from the coupling position, measure the current magnitude when the anode is coupled with different numbers of cathode tube segments respectively, analyze the variation law of the coupled current density with the coupled distance, and evaluate the influence distance of the coupled current on the cathode tube segment.

[0016] The beneficial effects of an experimental device and experimental method for measuring the dissimilar metal contact current in a seawater pipeline of the present invention are as follows: Compared with the prior art, the present invention first adopts a tubular structure and a pipeline system experiment, realizes the measurement of the structure-level dissimilar metal contact current in a seawater pipeline under simulated working conditions, and effectively improves the experimental ability of dissimilar metal contact corrosion; The present invention also includes a dissimilar metal contact current test module with replaceable experimental tube segments, which is easy to install and meets the contact current test experiments of various different pipeline structures and pipeline material pairs; The designed anode and cathode experimental tube segments of the present invention can adopt segmented ring-shaped specimens to realize the on-line measurement of the dissimilar metal contact current magnitude and influence distance under different working conditions and different anode-cathode area ratios. Brief Description of the Drawings

[0017] Figure 1 It is a schematic diagram of the overall structure of the experimental device in the embodiment of the present invention; Figure 2 It is the test-stage tube structure in the embodiment of the present invention Figure 1 The side view in the A direction in

[0018] Description of the reference numerals: inlet valve 1, outlet valve 2, environmental factor sensor 3, stirrer 4, test box 5, zero-resistance current meter 6, wire 7, cathode tube segment 8, anode tube segment 9, insulating flange 10, insulating gasket 11, fastener 12, circulation pipeline 13, electromagnetic flowmeter 14, variable-frequency corrosion-resistant pump 15, drain valve 16, circulation water tank 17. Detailed Embodiments

[0019] To enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be described below in conjunction with the detailed embodiments and the drawings.

[0020] Embodiment 1 As Figure 1-2 shown, an experimental device for measuring the dissimilar metal contact current in a seawater pipeline includes a test mechanism and a circulation mechanism. The test mechanism is used to measure the dissimilar metal contact current magnitude and influence distance under different dissimilar metal pairs, different area ratios, etc. of the cathode tube segment and the anode tube segment in an aqueous solution. The circulation mechanism is used to assist the experimental medium to complete circulation in the test mechanism.

[0021] Specifically, the test mechanism includes a test-level tube, a wire 7, a zero-resistance ammeter 6, and a test box 5. The circulation mechanism includes a circulation pipeline 13, a frequency-converting corrosion-resistant pump 15, a circulation water tank 17, a valve assembly, and an electromagnetic flowmeter 14. The test box, the frequency-converting corrosion-resistant pump, and the electromagnetic flowmeter are connected in series on the circulation pipeline. Both ends of the circulation pipeline are installed on the circulation water tank. The test-level tube is placed inside the test box. The zero-resistance ammeter is connected to the test-level tube through a wire. The valve assembly controls the seawater flow rate in the circulation water tank and the circulation pipeline.

[0022] According to the experimental requirements, the experimental medium can be different electrolyte solutions such as natural seawater, sand-containing seawater, artificial seawater, and salt solutions. Further, in order to fully mix the solution evenly, a stirrer 4 is provided inside the circulation water tank, and the stirring end of the stirrer extends into the circulation water tank. Figure 1 The stirrer includes a stirring motor, a stirring shaft, and stirring fan blades. The arrow direction in the figure indicates the rotation direction of the stirring shaft.

[0023] Further, to maintain a constant temperature state and reduce the influence of other factors, a constant-temperature circulation water tank is used for the circulation water tank, with a temperature control switch installed inside. An environmental factor sensor 3 is provided inside the circulation water tank, and the environmental factor sensor can regulate the salinity, pH value, conductivity, etc. of the experimental medium.

[0024] Further, the circulation water tank includes a water inlet, a water outlet, a circulation outlet, and a circulation inlet. The circulation outlet and the water outlet are provided at the lower part of the circulation water tank, and the circulation inlet and the water inlet are provided at the upper part of the circulation water tank.

[0025] The valve assembly includes an inlet valve 1, an outlet valve 2, a drain valve 16, and not less than one control valve. The control valves are connected in series on the circulation pipeline. The inlet valve is provided at the water inlet of the circulation water tank, and the outlet valve is provided at the water outlet of the circulation water tank. One of the control valves is provided between the circulation outlet and the frequency-converting corrosion-resistant pump. A drain port is provided on the circulation pipeline between the frequency-converting corrosion-resistant pump and the circulation outlet, and the drain valve is provided at the drain port. Figure 1 The arrows at the positions of the inlet valve and the outlet valve indicate the medium flow direction.

[0026] The test-level tube includes a cathode tube section 8, an anode tube section 9, a fastener 12, and an insulating flange 10. Figure 2 In the figure, the cathode tube section and the anode tube section are in a coincident state when viewed from the side, so they are jointly indicated by 8 and 9. The fastener penetrates through the cathode tube section and the anode tube section, and the insulating flange is installed at both ends of the fastener to clamp the middle cathode tube section and anode tube section. The fastener, the circulation pipeline, the frequency-converting corrosion-resistant pump, the circulation water tank, the valve assembly, the electromagnetic flowmeter, and the test box are all made of insulating materials to ensure the insulation between the dissimilar metal contact current test module and the system.

[0027] According to the different metals to be tested, the cathode tube section and the anode tube section can be replaced with different metal materials according to experimental requirements, so as to realize the test of the contact current magnitude and the influence distance of different dissimilar metal pairs and different area ratios under different conditions.

[0028] The cathode tube section is the metal with a higher potential in the dissimilar metal pair to be tested, such as copper in the copper-steel pair. A wire with a rubber sleeve is welded outside the tube, and the welding part is sealed with insulating glue, such as epoxy putty. During the test, it is connected to the negative pole of the zero-resistance ammeter. The anode tube section is the metal with a lower potential in the dissimilar metal pair to be tested, such as steel in the copper-steel pair. A wire with a rubber sleeve is welded outside the tube, and the welding part is sealed with insulating putty. During the test, it is connected to the positive pole of the zero-resistance ammeter. Both the cathode tube section and the anode tube section can be connected and composed of ring-shaped specimens of the same length. Rubber sealing rings are used to separate the ring-shaped specimens. Each ring-shaped specimen is welded with a test wire. The ring-shaped specimens and the sealing rings are assembled through two end flanges and fasteners. Through the above structure, the contact current test under different cathode-anode area ratios can be realized. At the same time, by measuring the weight change of the ring-shaped specimens before and after the experiment, the contact corrosion rate of dissimilar metals can be tested.

[0029] There is no special limitation on the pipe diameters of the tested cathode tube section and anode tube section, and any metal material can be selected according to research needs. The components used for the contact current test are not limited to the zero-resistance ammeter, including all electrochemical workstations with the same function as the zero-resistance ammeter that can measure current, and the test accuracy is selected according to the current range of the tested system.

[0030] Specifically, the cathode tube section includes no less than two copper alloy rings and insulating sealing gaskets 11. The insulating sealing gaskets are arranged between adjacent two copper alloy rings. Each copper alloy ring is separately connected to the zero-resistance ammeter through a wire. The anode tube section includes no less than four steel pipe sections and insulating sealing gaskets. In this embodiment, the number of steel pipe sections is twice the number of copper alloy rings. Insulating sealing gaskets are arranged between two adjacent steel pipe sections. Each steel pipe section is separately connected to the zero-resistance ammeter through a wire.

[0031] Embodiment 2 An experimental method for an experimental device for testing the contact current of dissimilar metals in a seawater pipeline includes the following steps: Step 1: Connect the frequency conversion corrosion-resistant pump, the circulation water tank, the control valve, the electromagnetic flowmeter, and the test water tank in series with a circulation water pipe. Place the stirring end of the stirrer in the seawater in the circulation water tank. Set the circulation water tank to a constant temperature state, and install environmental factor sensors; Step 2: Select the metal ring materials for the cathode tube section and the anode tube section according to the experimental requirements. Use insulating sealing gaskets to separate the metal rings of the cathode tube section and the anode tube section one by one. Use fasteners and non-metallic insulating flanges to clamp the cathode tube section and the anode tube section. Each metal ring is connected to a zero-resistance galvanometer through a rubber-sleeved wire. Place the cathode tube section and the anode tube section into the test water tank simultaneously. Step 3: After filling with seawater, close the inlet valve, outlet valve, and drain valve. Open the control valve, set the seawater temperature to a constant state, and the flow rate to 2 - 4 m / s. Each component starts to operate according to the set operating parameters. Step 4: Set the time period for measuring the galvanic current density. Use a zero-resistance galvanometer to measure the galvanic current density between the dissimilar metals of the cathode tube section and the anode tube section at each time period. Measure once a day after 24 hours. End the measurement when the magnitude of the galvanic current density does not change significantly with time.

[0032] Specifically, fix the cathode area of the cathode tube section. Gradually increase the number of anode tube sections from the coupling position one by one. Measure the current magnitude when the cathode is coupled with different numbers of anode tube sections respectively. Analyze the variation law of the galvanic current density with the coupling distance, and evaluate the influence distance of the galvanic current on the anode tube section. Fix the anode area of the anode tube section. Gradually increase the number of cathode tube sections from the coupling position one by one. Measure the current magnitude when the anode is coupled with different numbers of cathode tube sections respectively. Analyze the variation law of the galvanic current density with the coupling distance, and evaluate the influence distance of the galvanic current on the cathode tube section.

[0033] Example 3 This example illustrates Examples 1 and 2 by the galvanic current magnitude and influence distance between a B10 copper alloy tube and a Q235 steel tube in still seawater at normal temperature.

[0034] The B10 copper alloy tube serves as the cathode tube section. Five sections of DN50 B10 copper alloy rings (2 cm / section) are isolated by insulating sealing gaskets and then fastened together by flanges and fasteners on both sides. Copper wires are welded to each ring.

[0035] The Q235 steel tube serves as the anode tube section. Ten sections of DN50 Q235 steel rings (2 cm / section) are isolated by insulating sealing gaskets and then fastened together by flanges and fasteners on both sides. Copper wires are welded to each ring.

[0036] According to Figure 1 and Figure 2 the schematic diagram of the replaceable dissimilar metal contact current test module shown, assemble the cathode and anode tube sections together through insulating gaskets; select the circulating water mode, open the inlet valve, close the inlet valve, outlet valve, and drain valve after filling with seawater, and open the remaining control valves.

[0037] Set the seawater temperature to 25 °C and the flow rate to 3 m / s. Turn on the temperature control switch, stirrer, sensors for environmental factors (temperature, salinity, conductivity, and pH value), electromagnetic flowmeter, and frequency conversion corrosion-resistant pump of the constant temperature circulating water tank, and the device starts to operate according to the set parameters.

[0038] During the experiment, the metal parts of the entire system are coupled together through external wires. At the start of the test, the coupled current density is measured once an hour. After 24 hours, it is measured once a day, and the duration is judged based on the change of the coupled current density. Generally, it ends when the magnitude of the current density does not increase significantly with time. A zero-resistance ammeter is used to measure the galvanic current between dissimilar metals by connecting to the wires of the cathode tube and the anode tube respectively.

[0039] By fixing the cathode area and making all 5 B10 copper alloy rings conduct, and gradually increasing the number of anode tube segments in sequence from the coupling position, the current magnitudes when the cathode is coupled with different numbers of anode tube segments are tested respectively, the variation law of the coupled current density with the coupling distance is analyzed, and the influence distance of the coupled current on the anode tube segments is evaluated. Conversely, by fixing the anode area and making all 10 Q235 steel rings conduct, and gradually increasing the number of cathode tube segments in sequence from the coupling position, the current magnitudes when the anode is coupled with different numbers of cathode tube segments are tested respectively, the variation law of the coupled current density with the coupling distance is analyzed, and the influence distance of the coupled current on the cathode tube segments is evaluated.

[0040] The above embodiments are only for illustrating the structural concept and characteristics of the present invention, aiming to enable ordinary technicians in the field to understand the content of the present invention and implement it accordingly, and shall not be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the essence of the content of the present invention should be covered within the protection scope of the present invention.

Claims

1. A test experimental device for the contact current of dissimilar metals in a seawater pipeline, characterized in that: It includes a test mechanism and a circulation mechanism. The test mechanism includes a test-stage tube, wires, a zero-resistance ammeter, and a test box. The circulation mechanism includes a circulation pipeline, a variable-frequency corrosion-resistant pump, a circulation water tank, a valve assembly, and an electromagnetic flowmeter. The test box, the variable-frequency corrosion-resistant pump, and the electromagnetic flowmeter are connected in series on the circulation pipeline. Both ends of the circulation pipeline are installed on the circulation water tank. The test-stage tube is placed inside the test box. The zero-resistance ammeter is connected to the test-stage tube through wires. The valve assembly controls the seawater flow rate inside the circulation water tank and the circulation pipeline.

2. The seawater pipeline dissimilar metal contact current test experimental device according to claim 1, characterized in that: The test-stage tube includes a cathode tube section, an anode tube section, fasteners, and insulating flanges. The fasteners penetrate through the cathode tube section and the anode tube section. The insulating flanges are installed at both ends of the fasteners to clamp the middle cathode tube section and anode tube section.

3. The experimental device for testing the contact current of dissimilar metals in a seawater pipeline according to claim 2, wherein: The cathode tube section includes no less than two high-potential metal alloy rings and insulating sealing gaskets. The insulating sealing gaskets are arranged between adjacent high-potential metal alloy rings. Each high-potential metal alloy ring is individually connected to the zero-resistance ammeter through a wire. The anode tube section includes no less than two low-potential metal alloy rings and insulating sealing gaskets. Insulating sealing gaskets are arranged between two adjacent low-potential metal alloy rings. Each low-potential metal alloy ring is individually connected to the zero-resistance ammeter through a wire.

4. The experimental device for testing the contact current of dissimilar metals in a seawater pipeline according to claim 1, wherein: It further includes a temperature control switch, an environmental factor sensor, and a stirrer. The temperature control switch and the environmental factor sensor are arranged inside the circulation water tank. The temperature control switch adjusts the temperature of the seawater inside the circulation water tank to maintain a constant temperature state. The stirring end of the stirrer extends into the circulation water tank.

5. The seawater pipeline dissimilar metal contact current test experimental device according to claim 1, characterized in that: The circulation water tank includes a water inlet, a water outlet, a circulation outlet, and a circulation inlet. The circulation outlet and the water outlet are arranged at the lower part of the circulation water tank. The circulation inlet and the water inlet are arranged at the upper part of the circulation water tank.

6. The seawater pipeline dissimilar metal contact current test experimental device according to claim 5, characterized in that The valve assembly includes an inlet valve, an outlet valve, a drain valve, and no less than one control valve. The control valves are connected in series on the circulation pipeline. The inlet valve is arranged at the water inlet of the circulation water tank. The outlet valve is arranged at the water outlet of the circulation water tank. One of the control valves is arranged between the circulation outlet and the variable-frequency corrosion-resistant pump. A drain port is arranged on the circulation pipeline between the variable-frequency corrosion-resistant pump and the circulation outlet. The drain valve is arranged at the drain port.

7. An experimental method for testing the contact current of dissimilar metals in a seawater pipeline, characterized in that, It includes the following steps: Step 1: Connect the variable-frequency corrosion-resistant pump, the circulation water tank, the control valves, the electromagnetic flowmeter, and the test water tank in series using a circulation water pipe. Place the stirring end of the stirrer in the seawater inside the circulation water tank. Set the circulation water tank to a constant temperature state and install the environmental factor sensor. Step 2: Select the metal ring materials for the cathode tube section and the anode tube section according to the experimental requirements. Use insulating sealing gaskets to separate the metal rings of the cathode tube section and the anode tube section one by one. Use fasteners and non-metallic insulating flanges to clamp the cathode tube section and the anode tube section. Each metal ring is connected to the zero-resistance ammeter through a rubber-sleeved wire. Place the cathode tube section and the anode tube section into the test water tank simultaneously. Step 3: After filling with seawater, close the inlet valve, outlet valve, and drain valve, open the control valve, set the seawater temperature to a constant state, and the flow rate to 2 - 4 m / s. Each component starts to operate according to the set operating parameters; Step 4: Set the time period for measuring the galvanic current density. Measure the galvanic current density between dissimilar metals of the cathode tube section and the anode tube section using a zero-resistance ammeter according to the time period, and measure once a day after 24 hours. End the measurement when the magnitude of the galvanic current density does not change significantly over time.

8. The experimental method of the experimental device for testing the contact current of dissimilar metals in a seawater pipeline according to claim 7, characterized in that, In the said Step 4, it includes: Fix the cathode area of the cathode tube section, gradually increase the number of anode tube sections in sequence from the coupling position, respectively test the current magnitudes when the cathode is coupled with different numbers of anode tube sections, analyze the variation law of the galvanic current density with the coupling distance, and evaluate the influence distance of the galvanic current on the anode tube section; Fix the anode area of the anode tube section, gradually increase the number of cathode tube sections in sequence from the coupling position, respectively test the current magnitudes when the anode is coupled with different numbers of cathode tube sections, analyze the variation law of the galvanic current density with the coupling distance, and evaluate the influence distance of the galvanic current on the cathode tube section.

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