Multi-angle erosion corrosion and in-situ electrochemical testing device

Abstract

The invention belongs to the technical field of pipeline erosion corrosion and electrochemical corrosion measurement, and particularly relates to a multi-angle erosion corrosion and in-situ electrochemical testing device which integrally keeps the basic characteristics of a pipeline, and the flow state in the pipeline is close to the actual pipeline flow state. The main body structure comprises an outer sleeve, an inner sleeve arranged in the outer sleeve, a reference electrode arranged on the outer sleeve, a working electrode and an auxiliary electrode arranged on the inner sleeve, and an electrochemical workstation connected with the reference electrode, the working electrode and the auxiliary electrode. According to the present invention, the erosion corrosion test of the metal sample and the coating sample at the fixed erosion angle can be achieved, the weightlessness and the electrochemical measurement can be performed, the erosion corrosion test of the metal sample and the coating sample under the cathode protection state can be achieved, and the corrosion data of the sample under the cathode protection can be obtained, and in addition, the positions of the working electrode, the auxiliary electrode and the reference electrode are fixed; obvious influence on the flow state is avoided, and the stability of the electrochemical testing process is facilitated.

Description

Technical field:

[0001] The invention belongs to the technical field of pipeline erosion corrosion and electrochemical corrosion measurement, and specifically relates to a multi-angle erosion corrosion and in-situ electrochemical testing device, which provides basic data for analyzing the erosion corrosion mechanism of a sample to be tested. Background technology:

[0002] Pipelines are an important part of industrial fields such as petroleum, chemical, electric power, and shipbuilding. At present, pipelines used in the industrial field are mainly made of metal materials. However, metal pipelines frequently fail due to corrosion during service, among which erosion corrosion is the most common type of corrosion.

[0003] Erosion corrosion is the damage caused when the relative movement between the metal surface and the corrosive medium exceeds a certain range. In the prior art, there are three types of test devices for studying erosion corrosion: rotary, jet and tube flow, which simulate the erosion process in different ways. The rotary test device fixes the test sample on a cylinder or a disc, and drives the test sample to move in the corrosive medium through the rotation of the motor to achieve the erosion effect. It is mainly used to evaluate the erosion corrosion resistance of the material itself. The jet test device directly sprays the fluid onto the sample surface through an ejector to simulate the erosion corrosion process. It is mainly used to determine the limiting flow rate of the material and study the erosion corrosion mechanism. The tube flow test device drives the fluid medium to flow in the pipe through a circulating pump to scour the metal sample. Generally, tubular or annular samples are used directly or the metal sample is embedded in the groove on the inner wall of the pipeline to simulate the actual fluid flow in the pipeline. It is mainly used for sample-level performance evaluation.

[0004] The scouring angle, also known as the angle of attack, refers to the angle formed by the fluid in the pipe and the inner wall surface of the pipe. The change of the scouring angle affects the scouring corrosion behavior of the metal by affecting the normal stress and shear stress on the metal surface. Generally, a jet test device or a rotary test device is used to study the effect of the scouring angle on the scouring corrosion of metals. For example, the English document X. Tang, LY Xu, YF Cheong. Electrochemical corrosion behavior of X-65 steel in the simulated oil–sand slurry. II: Synergism of erosion and corrosion, Corrosion Science, 2008, 50 (5): 1469-1474. discloses a method for evaluating the effect of the scouring angle on the scouring corrosion behavior of materials through a jet scouring test device. Chinese patent 200810249618.6 discloses a multifunctional underwater jet cavitation test device, which simulates the process of scouring corrosion and cavitation corrosion on the surface of a metal sample by spraying a high-pressure liquid flow. Chinese patent 202410246317.7 discloses a rotary scouring in-situ electrochemical testing device, which simulates the scouring process of liquid on the metal surface by the high-speed rotation of the rotating disc, and can perform in-situ electrochemical testing. Xing Jiandong, Gao Yimin, Zhang Guoshang. Experimental study on scouring corrosion and wear of stainless steel and high carbon steel. Journal of Xi'an Jiaotong University, 2004,

[0005] (05): 469-473. A method for evaluating the effect of scouring angle on scouring corrosion behavior of materials by a rotary scouring test device is disclosed. The fluid scouring process simulated by the jet test device and the rotary test device is significantly different from the actual flow state inside the pipeline, and the test data obtained has little guiding significance for the actual application and design of the pipeline.

[0006] The internal flow state of the tube flow test device is closest to the actual pipeline, and can most directly simulate the erosion and corrosion behavior of the pipeline. However, due to the limitations of the structural characteristics, it can only test the erosion and corrosion performance of actual samples in pipelines such as straight pipes, elbows, valves, reducers, and tees. It is impossible to use sheet specimens to study the erosion and corrosion performance of materials at different erosion angles. For example, a tube flow inner wall erosion and corrosion test device disclosed in Chinese Patent 201310248151.4 includes: a power pump, a discharge pipe I, a stirring pump, a cooler, an electromagnetic flowmeter, an auxiliary electrode, a sample to be tested, a reference electrode, a discharge pipe II, and a slurry tank. The specific structure is as follows: the input end of the stirring pump is directly connected to the slurry tank, and a cooler is arranged on the pipeline connected to the slurry tank at the output end of the stirring pump. The cooler as a cooling system is independent of the slurry tank, and the pipeline connected to the slurry tank at the output end of the stirring pump is equipped with a bypass: the discharge pipe is directly connected to the slurry tank, and the discharge pipe is connected to the slurry tank at the output end of the stirring pump. Material pipe I; the slurry tank is connected to the power pump and the stirring pump through pipelines respectively, the input end of the power pump is directly connected to the slurry tank through the pipeline, and the pipeline connecting the output end of the power pump with the slurry tank is provided with: an electromagnetic flowmeter and a sample to be tested, and the electromagnetic flowmeter is provided on the test pipe section where the power pump leads to the sample to be tested; the pipeline connecting the output end of the power pump with the slurry tank is equipped with a bypass: a discharge pipe II; the pipeline connecting the output end of the power pump with the slurry tank is provided with an auxiliary electrode and a reference electrode, and the reference electrode and the auxiliary electrode are installed on the pipeline near the sample to be tested. Chinese Patent 202411505121.1 discloses a test device for electrochemical online testing and hanging plate test of pipeline erosion corrosion, including: a high-pressure gas cylinder, a liquid storage tank, a ventilation pipeline, a pump body, a medium pipeline, a test pipeline, an electrochemical online test unit and a hanging plate test unit; the high-pressure gas cylinder is used to store test gas; the liquid storage tank is used to store test medium; the ventilation pipeline is directly connected to the bottom of the liquid storage tank; the high-pressure gas cylinder passes the test gas into the liquid storage tank through the ventilation pipeline; the inlet end of the pump body is connected to the liquid storage tank, and the outlet end of the pump body is connected to the medium pipeline; the medium pipeline is connected to the test pipeline; the pump body draws the test medium out through a section of the medium pipeline and then enters the test pipeline; the test pipeline includes: an elbow section and a straight pipe section, the elbow section is connected to the medium pipeline, and the straight pipe section The electrochemical online test unit comprises: a three-electrode system of an elbow section, a three-electrode system of a straight pipe section and an electrochemical workstation; the three-electrode system of the elbow section is arranged at the elbow section of the test pipeline; the three-electrode system of the elbow section comprises: a first working electrode, a first reference electrode and a first auxiliary electrode; the three-electrode system of the straight pipe section is arranged at the straight pipe section of the test pipeline; the three-electrode system of the straight pipe section comprises: a second working electrode, a second reference electrode and a second auxiliary electrode; the electrochemical workstation is respectively connected to the corresponding electrodes of the three-electrode system of the elbow section and the three-electrode system of the straight pipe section, for performing different electrochemical detection technology tests; the coupon test unit is arranged at the elbow section or the straight pipe section of the test pipeline; the coupon test unit comprises: a test piece fixture and a test piece; the test piece is embedded in the test piece fixture.The scouring corrosion test is carried out by fixing the sheet sample on the surface of the tubular sample. The scouring angle of the installed sheet sample can only be adjusted by changing the shape of the tubular sample. The adjustment range is limited, and the shape change of the tubular sample will cause the flow state to change, making it difficult to conduct research on variable scouring angles.

[0007] Therefore, a multi-angle erosion-corrosion and in-situ electrochemical testing device was developed and designed, which can be used in conjunction with the existing tube flow test device to evaluate the corrosion behavior of materials at different erosion angles through methods such as corrosion morphology changes, corrosion weight loss, and in-situ electrochemical testing. Summary of the invention:

[0008] The purpose of the present invention is to overcome the shortcomings of the prior art and to develop and design a multi-angle erosion-corrosion and in-situ electrochemical testing device, so as to realize erosion-corrosion testing of metal samples, coating samples, etc. according to preset erosion angles in a pipeline system or a pipe flow erosion-corrosion testing device, and to perform in-situ electrochemical testing on the samples to be tested.

[0009] In order to achieve the above-mentioned purpose, the main structure of the multi-angle erosion-corrosion and in-situ electrochemical testing device of the present invention comprises an outer sleeve and an inner sleeve arranged therein, a reference electrode arranged on the outer sleeve, a working electrode and an auxiliary electrode arranged on the inner sleeve, and an electrochemical workstation respectively connected to the reference electrode, the working electrode and the auxiliary electrode;

[0010] Specifically, the outer sleeve is connected to the inner sleeve through reducers arranged at both ends, the middle part of the inner sleeve is arranged inside the outer sleeve, and the two ends extend out of the outer sleeve;

[0011] The reference electrode is arranged on the outer sleeve;

[0012] The working electrode is arranged in the middle of the inner sleeve;

[0013] The auxiliary electrodes are brushed on both ends of the inner sleeve;

[0014] The reference electrode, the working electrode and the auxiliary electrode are respectively connected to the electrochemical workstation through wires;

[0015] The main structure of the outer sleeve includes a four-way joint and large sleeves arranged before and after it, and a reference electrode and a gland arranged on the four-way joint;

[0016] The main structure of the inner sleeve comprises small sleeves arranged at the front and the back, a support frame and threaded holes arranged thereon.

[0017] The inner sleeve involved in the present invention is divided into a large-angle inner sleeve (30 < flushing angle ≤ 90°) and a small-angle inner sleeve (0° ≤ flushing angle ≤ 30°) according to the applicable range of the flushing angle:

[0018] The large-angle inner sleeve is provided with four metal support frames, each of which is provided with an internal threaded hole. The angle α between the center lines of the two internal threaded holes located in the same horizontal plane and the support frame is the flushing angle of the sample to be tested;

[0019] The small-angle inner sleeve is provided with two metal support frames, each of which is provided with two internal threaded holes. The angle α between the center line of the two internal threaded holes on the same support frame and the support frame is the flushing angle of the sample to be tested;

[0020] The reference electrode is set in the four-way joint, and the bottom is flush with the inner wall of the four-way joint to avoid affecting the flow state of water. The reference electrode has a wire to connect to the electrochemical workstation;

[0021] The working electrode is the sample to be tested, and is provided with a blind hole with internal threads, which has the same size as the threaded hole and a position corresponding to the threaded hole; a wire is led out of the working electrode and passes through a gland to be connected to the electrochemical workstation, and the gland is installed in a four-way connector to seal the wire;

[0022] The auxiliary electrode is a titanium-based precious metal oxide coating, which is applied on the inner wall of the small sleeve;

[0023] The material of the large sleeve is PVC plastic;

[0024] The small sleeve and the support frame are both made of titanium alloy.

[0025] The multi-angle erosion corrosion and in-situ electrochemical testing device of the present invention is installed as a whole in a pipeline when it is working. When the fluid flows inside the pipeline, it continuously erodes the sample to be tested at a preset erosion angle. By performing in-situ electrochemical testing on the sample to be tested, its corrosion development process is monitored.

[0026] Compared with the prior art, the present invention maintains the basic characteristics of the pipeline as a whole, and the flow state in the pipe is close to the actual pipeline flow state, which can effectively simulate the actual working conditions of the pipeline, realize the erosion corrosion test of metal samples and coating samples at a fixed erosion angle, can perform weight loss and electrochemical measurements, and realize the erosion corrosion test of metal samples and coating samples under cathodic protection, and obtain the corrosion data of the samples under cathodic protection. In addition, the positions of the working electrode, the auxiliary electrode, and the reference electrode are fixed, which will not have a significant impact on the flow state, which is conducive to the stability of the electrochemical test process. Among them, the auxiliary electrode is tubular and symmetrically distributed on both sides of the working electrode, ensuring that the area of ​​the auxiliary electrode is more than five times that of the working electrode, thereby improving the ability of the auxiliary electrode to receive electrochemical signals and the accuracy of the electrochemical test; it has a simple structure, a scientific and reliable principle, can be directly connected to a pipeline system or a pipe flow erosion corrosion test system, and the device size can be selected according to pipeline requirements. It has a wide range of applications and strong adaptability. Description of the drawings:

[0027] Figure 1 This is a schematic diagram of the main structural principle of Example 1 of the present invention.

[0028] Figure 2 This is a schematic diagram of the main structural principle of the outer sleeve involved in Example 1 of the present invention.

[0029] Figure 3 This is a schematic diagram of the main structural principle of the inner sleeve involved in Example 1 of the present invention.

[0030] Figure 4 It is a top view of the main structure of the inner sleeve involved in Example 1 of the present invention.

[0031] Figure 5 This is an assembly diagram of the main structure of the inner sleeve involved in Example 1 of the present invention.

[0032] Figure 6 This is a schematic diagram of the main structural principle of Example 2 of the present invention.

[0033] Figure 7 This is a schematic diagram of the main structural principle of the inner sleeve involved in Example 2 of the present invention.

[0034] Figure 8 This is a top view of the main structure of the inner sleeve involved in Example 2 of the present invention. Specific implementation method:

[0035] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0036] Embodiment 1:

[0037] The multi-angle erosion-corrosion and in-situ electrochemical testing device involved in this embodiment is a large-angle multi-angle erosion-corrosion and in-situ electrochemical testing device, which is used to perform erosion-corrosion tests and electrochemical tests on the sample to be tested at an erosion angle of 60°. The main structure is as follows Figure 1 As shown, it includes an outer sleeve 1, a reducer 2, an inner sleeve 3, a reference electrode 4, a working electrode 5, an auxiliary electrode 6, a wire 7 and an electrochemical workstation 8;

[0038] The outer sleeve 1 is connected to the inner sleeve 3 through reducers 2 arranged at both ends. The middle part of the inner sleeve 3 is arranged inside the outer sleeve 1, and both ends extend out of the outer sleeve 1.

[0039] The outer sleeve 1 is provided with a reference electrode 4;

[0040] A working electrode 5 is disposed in the middle of the inner sleeve 3, and auxiliary electrodes 6 are coated on both ends, and the area of ​​the auxiliary electrode 6 is more than five times the area of ​​the working electrode 5;

[0041] The reference electrode 4, the working electrode 5 and the auxiliary electrode 6 are connected to the electrochemical workstation 8 through the wires 7 respectively;

[0042] Among them, the main structure of the outer sleeve 1 is as follows Figure 2 As shown, it includes a four-way connector 11, a large sleeve 12 and a cable gland 13; the front and rear interfaces of the four-way connector 11 are respectively connected to the large sleeve 12, and the upper and lower interfaces are respectively connected to the reference electrode 4 and the cable gland 13;

[0043] The main structure of the inner sleeve 3 is as follows Figure 3-4 As shown, it includes a small sleeve 31, a support frame 32 and a threaded hole 33; two small sleeves 31 are connected by four support frames 32, each support frame 32 is provided with a threaded hole 33, and the angle α between the center line of the two threaded holes 33 located in the same horizontal plane and the support frame 32 is 60°, that is, the flushing angle of the sample to be tested.

[0044] When the working electrode 5 involved in this embodiment is assembled, Figure 5 As shown:

[0045] First, it is fixed to the support frame 32 by means of plastic bolts 100;

[0046] Then, insulating gaskets 200 are arranged on the upper and lower surfaces of the support frame 32;

[0047] Finally, a wire 7 is arranged between the insulating spacers 200 of the working electrode 5 , and the wire 7 extends out of the outer sleeve through the cable gland 13 so that the working electrode 5 is connected to the electrochemical workstation 8 .

[0048] Embodiment 2:

[0049] The multi-angle erosion-corrosion and in-situ electrochemical testing device involved in this embodiment is a small-angle multi-angle erosion-corrosion and in-situ electrochemical testing device, which is used to perform erosion-corrosion tests and electrochemical tests on the sample to be tested at an erosion angle of 30°. The main structure is the same as that of Embodiment 1. Figure 6 As shown, the difference lies in the main structure of the inner sleeve 3, such as Figure 7-8 As shown, two small sleeves 31 are connected by two support frames 32, each support frame 32 is provided with two threaded holes 33, and the angle α between the center line of the two threaded holes 33 on the same support frame 32 and the support frame 32 is 30°, that is, the flushing angle of the sample to be tested.

Claims

1. A multi-angle erosion corrosion and in-situ electrochemical testing device, characterized in that: The main structure includes an outer sleeve and an inner sleeve arranged therein, a reference electrode arranged on the outer sleeve, a working electrode and an auxiliary electrode arranged on the inner sleeve, and an electrochemical workstation respectively connected to the reference electrode, the working electrode and the auxiliary electrode; the outer sleeve is connected to the inner sleeve through reducers arranged at both ends, the middle part of the inner sleeve is arranged inside the outer sleeve, and both ends extend out of the outer sleeve.

2. A multi-angle erosion-corrosion and in-situ electrochemical testing device according to claim 1, characterized in that: The reference electrode is arranged on the outer sleeve; the working electrode is arranged in the middle of the inner sleeve; the auxiliary electrode is painted on both ends of the inner sleeve; the reference electrode, the working electrode and the auxiliary electrode are respectively connected to the electrochemical workstation through wires.

3. A multi-angle erosion-corrosion and in-situ electrochemical testing device according to claim 1 or 2, characterized in that: The main structure of the outer sleeve comprises a four-way joint and large sleeves and glands arranged at the front and rear thereof.

4. The multi-angle erosion-corrosion and in-situ electrochemical testing device according to claim 3, characterized in that: The main structure of the inner sleeve comprises small sleeves arranged at the front and the back, a support frame and threaded holes arranged thereon.

5. The multi-angle erosion-corrosion and in-situ electrochemical testing device according to claim 4, characterized in that: The inner sleeve is divided into a large-angle inner sleeve and a small-angle inner sleeve according to the applicable range of the flushing angle.

6. The multi-angle erosion-corrosion and in-situ electrochemical testing device according to claim 5, characterized in that: The large-angle inner sleeve is provided with four metal support frames, each of which is provided with an internal threaded hole, and the angle α between the center lines of the two internal threaded holes located in the same horizontal plane and the support frame is the flushing angle of the sample to be tested.

7. The multi-angle erosion-corrosion and in-situ electrochemical testing device according to claim 5, characterized in that: The small-angle inner sleeve is provided with two metal support frames, each of which is provided with two internal threaded holes. The angle α between the center lines of the two internal threaded holes on the same support frame and the support frame is the flushing angle of the sample to be tested.

8. The multi-angle erosion-corrosion and in-situ electrochemical testing device according to claim 4, characterized in that: The reference electrode is set in the four-way joint, with the bottom flush with the inner wall of the four-way joint, and is connected to the electrochemical workstation through a wire; the working electrode is the sample to be tested, and is provided with a blind hole with internal threads, the size of which is the same as the threaded hole, and the position corresponds to the threaded hole; a wire is led out of the working electrode and passes through the cable gland to be connected to the electrochemical workstation, and the cable gland is installed in the four-way joint to seal the wire; the auxiliary electrode is a titanium-based precious metal oxide coating, which is coated on the inner wall of the small sleeve; the material of the large sleeve is PVC plastic; the material of the small sleeve and the support frame are both titanium alloy.

9. A multi-angle erosion-corrosion and in-situ electrochemical testing device according to claim 1 or 2, characterized in that: When working, the whole is installed in the pipeline. When the fluid flows inside it, it continuously flushes the sample to be tested at a preset flushing angle. By performing in-situ electrochemical testing on the sample to be tested, its corrosion development process is monitored.

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