A pipeline stray current detection device and test method based on multi-coupling array electrodes

Abstract

The invention discloses a pipeline stray current detection device and a test method based on a multi-coupling array electrode, relates to the technical field of stray current detection, belongs to the field of stray current interference and cathodic protection monitoring of metal pipelines, and is composed of an experimental box, a stray current test module, a simulated pipe section module, a stray current application module and a cathodic protection module; the stray current test module comprises a multi-coupling array electrode group, a stray current collector and a test line I; the pipeline stray current detection device and a test method based on a multi-coupling array electrode of the invention adopt a multi-coupling array electrode, and according to the characteristics of the stray current, the electrode is placed at different positions such as stray current inflow, outflow, coating damage, etc., effectively measuring the local corrosion of the metal surface at a specific position and under the coating, not only being able to simulate and monitor different types of corrosion at different positions under stray current interference, but also being able to simultaneously evaluate the effectiveness of cathodic protection.

Description

Technical Field

[0001] The invention relates to the technical field of stray current detection, and belongs to the field of metal pipeline stray current interference and cathode protection monitoring, and specifically to a pipeline stray current detection device and a test method based on multiple coupling array electrodes. Background Art

[0002] With the rapid development of my country's economy, the large-scale construction of high-voltage transmission and transformation lines and electrified rail transit has led to a continuous increase in the number of buried metal pipelines. The stray current interference of power facilities and electrified rails on buried metal pipelines has become increasingly obvious, aggravating pipeline corrosion and seriously threatening the safe operation of pipelines.

[0003] At present, cathodic protection and coating dual protection are the most common and effective corrosion protection methods for buried metal pipelines. Stray current detection is mainly achieved by measuring the pipe-to-ground potential and current. Coating defects or damage and stray current interference may cause the pipe-to-ground potential to deviate from the cathodic protection potential, thereby causing pipeline corrosion. Therefore, measuring the pipe-to-ground potential alone is not enough to evaluate the efficiency of cathodic protection and the interference intensity of stray current.

[0004] Research shows that where stray current enters the pipeline, the steel is cathodically polarized and is less susceptible to corrosion; whereas where the stray current leaves the pipeline, the steel potential shifts to the anode, promoting corrosion. The location where the stray current enters and leaves the pipeline may be affected by the location and size of coating defects and the distribution of soil resistivity, resulting in high randomness of stray current interference. Therefore, the detection of stray current needs to cover the stray current corrosion location, corrosion mode, and interference intensity.

[0005] The traditional test piece method is an intuitive and effective detection method. On-site detection and indoor simulation experiments are mainly carried out based on the principle of the test piece method. However, this test can only reflect the local stray current interference of the pipeline at the buried position of the test piece, but cannot reflect the overall situation. As a result, the existing detection operation has certain limitations and cannot accurately reflect the situation of stray current interference at different positions of the pipeline. Summary of the invention

[0006] To solve the above problems, the purpose of the present invention is to provide a pipeline stray current detection device and test method based on multiple coupling array electrodes, which can accurately reflect the situation of stray current interference at different positions of the pipeline.

[0007] In order to achieve the above object, the present invention is implemented through the following technical solutions:

[0008] A pipeline stray current detection device based on a multi-coupled array electrode, comprising an experimental box (A), a stray current test module (B), a simulated pipe section module (C), a stray current application module (D) and a cathodic protection module (E);

[0009] The experimental box (A) comprises a rectangular box without a cover, the interior of the rectangular box is filled with an experimental medium, the material of the rectangular box is organic glass, polytetrafluoroethylene material or polyvinyl chloride material; the experimental medium is soil or sand;

[0010] The stray current test module (B) comprises a multi-coupled array electrode group, a stray current collector and a test line I; the multi-coupled array electrode group consists of a first array electrode, a second array electrode and a third array electrode, the stray current collector has a built-in zero-resistance ammeter and a high-resistance voltmeter to accurately measure the electrode potential and current of each metal wire single electrode in the above three array electrodes; the tail ends of the first array electrode, the second array electrode and the third array electrode are all connected to the test line I, and the other end of the test line I is connected to the corresponding interface of the stray current collector;

[0011] The metal wire bundles of the first array electrode, the second array electrode and the third array electrode are arranged in 4×25, 10×10 or 6×15 arrangements;

[0012] The simulated pipe section module (C) comprises a test piece I, a test piece II and a test piece III of the same material and size; the test pieces I, II and III are connected in series on the insulating pipe section via a test piece connecting line to simulate coating defects at different positions along the pipeline; the test piece I is connected to the corresponding interface of the stray current collector via a test line II;

[0013] The test pieces I, II and III are encapsulated with epoxy resin, leaving 1 to 6.5 cm in the middle of the upper surface. 2 Exposure;

[0014] The stray current applying module (D) comprises a direct current source, both ends of which are connected to titanium mesh electrodes through wires to simulate on-site stray currents, and select to apply output signals of different magnitudes to simulate stray current interference of different intensities;

[0015] The cathodic protection module (E) includes a power supply, which provides cathodic protection for the pipeline stray current detection device based on the multi-coupled array electrode. The power supply is connected to three electrodes through connecting wires, specifically: the working electrode connecting wire is connected to the test piece III, the counter electrode connecting wire is connected to the counter electrode, and the reference electrode connecting wire is connected to the reference electrode.

[0016] Preferably, the power source is a potentiostat or an electrochemical workstation.

[0017] Preferably, the counter electrode is a titanium mesh electrode or a platinum electrode.

[0018] Preferably, the reference electrode is a saturated Cu / CuSO4 electrode or a saturated calomel electrode.

[0019] Preferably, the material of the test pieces I, II and III is X65, X70 or X80 grade pipeline steel.

[0020] The present invention also includes a method for testing stray current interference using the above-mentioned pipeline stray current detection device based on multiple coupling array electrodes, comprising the following steps:

[0021] ① Use the test piece connecting wire to connect test piece I, test piece II and test piece III, leaving 1 to 6.5 cm for fixing 2 After the exposed area is sealed with epoxy resin for later use, all connection points must be insulated; a test medium of about 2 to 3 cm in height is laid in the box, the insulating pipe section is placed on the test medium, and then the three test pieces I, II and III are placed on the insulating pipe section, ensuring that the three test pieces are at the same height;

[0022] ② The three array electrodes are buried horizontally on the sides of the three test pieces respectively, so that the electrode surfaces do not touch but are as close as possible to the exposed parts of the test pieces. The test lines of the test pieces and array electrodes are connected to the corresponding interfaces of the stray current collector respectively;

[0023] The three array electrodes are a first array electrode, a second array electrode and a third array electrode;

[0024] Two titanium mesh electrodes are buried at both ends of the insulating pipe section, and the center height of the titanium mesh electrodes is kept consistent with that of the three test pieces as much as possible; the titanium mesh electrode wires are connected to both ends of the DC source;

[0025] ③ On the other side of the three test pieces, that is, the side opposite to the array electrode, a reference electrode and a counter electrode are buried respectively. The height of the center point of the counter electrode is as consistent as possible with the height of the test piece, and the tip of the reference electrode is as close to the test piece as possible, but not touching it; the power supply is connected to the corresponding electrodes through the three-electrode test wires; the power supply is a constant potential instrument or an electrochemical workstation;

[0026] ④ Continue to add experimental medium until the test piece and array electrodes are completely covered. The height of the medium added should be at least 5 cm higher than the horizontal position of the test piece. Do not form voids when adding the experimental medium and compact it as much as possible.

[0027] ⑤ Turn on the power supply to provide cathodic protection, under-protection or over-protection for the test piece according to the test requirements; turn on the DC source to provide simulated stray current interference for the test piece, and adjust the stray current intensity according to the test requirements; turn on the stray current collector, and the built-in zero-resistance ammeter and high-resistance voltmeter of the instrument will start working immediately to accurately measure the electrode potential and current of each metal wire single electrode of the three array electrodes;

[0028] ⑥ Export the test data and use the drawing software to display the surface potential and current distribution of the array electrode in three dimensions. Determine the cathode or anode current by coupling the positive and negative potential and current collected at the location of the array electrode, further determine the corrosion conditions of different parts of the pipeline, and identify the corrosion types at different locations of the pipeline under the interference of stray current.

[0029] Compared with the prior art, the present invention has the following advantages:

[0030] The invention discloses a pipeline stray current detection device and test method based on multiple coupling array electrodes. Multiple coupling array electrodes are used to place electrodes at different positions such as stray current inflow, outflow, and coating damage according to the characteristics of stray current, so as to effectively measure the local corrosion of the metal surface and under the coating at a specific position. The device can not only simulate and monitor different types of corrosion at different positions under the interference of stray current, but also simultaneously evaluate the effectiveness of cathodic protection.

[0031] The pipeline stray current detection device and test method based on multiple coupled array electrodes of the present invention overcome the limitation that the traditional test piece method cannot reflect the overall pipeline stray current interference. By cyclically scanning the points and current distribution on the surface of the metal wire bundle electrode, the local corrosion characteristics and electrochemical reaction process of the pipeline can be characterized. It has the advantages of being more comprehensive and systematic, and the data is more reliable and effective. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a schematic diagram of the metal wire arrangement of the 4×25 electrode array;

[0033] Figure 2 It is a schematic diagram of the metal wire arrangement of the 6×15 electrode array;

[0034] Figure 3 It is a schematic diagram of the overall structure of a pipeline stray current detection device based on multiple coupling array electrodes;

[0035] Figure 4 This is a test connection diagram of a pipeline stray current detection device based on multiple coupling array electrodes.

[0036] Figure 5 This is a schematic diagram of the average distribution of electrode current density at different positions of the pipeline stray current detection device using three 25-row and 4-column multi-coupled array electrodes under the interference of OCP stray current;

[0037] Figure 6 Schematic diagram of the average distribution of electrode current density at different positions of the pipeline stray current detection device using three 25-row and 4-column multi-coupled array electrodes under OCP+10mV stray current interference.

[0038] Figure numerals: 1. box; 2. experimental medium; 3. first array electrode; 4. second array electrode; 5. third array electrode; 6. test line I; 7. stray current collector; 8. insulating pipe section; 9. test piece I; 10. test piece II; 11. test piece III; 12. test piece connecting line; 13. test line II; 14. DC source; 15. conductor; 16. titanium mesh electrode; 17. power supply; 18. working electrode connecting line; 19. counter electrode connecting line; 20. counter electrode; 21. reference electrode connecting line; 22. reference electrode. DETAILED DESCRIPTION

[0039] The object of the present invention is to provide a pipeline stray current detection device and a test method based on a multi-coupling array electrode. The present invention is further described below in conjunction with specific embodiments.

[0040] Example 1

[0041] A pipeline stray current detection device based on multiple coupled array electrodes, such as Figure 3 and Figure 4 As shown, it consists of an experimental box (A), a stray current test module (B), a simulated pipe section module (C), a stray current application module (D) and a cathodic protection module (E);

[0042] like Figure 3 As shown, the experimental box (A) comprises a rectangular box 1 without a cover, the interior of the rectangular box 1 is filled with an experimental medium 2, and the material of the rectangular box 1 is organic glass, polytetrafluoroethylene material or polyvinyl chloride material; the experimental medium is soil or sand;

[0043] The stray current test module (B) comprises a multi-coupled array electrode group, a stray current collector 7 and a test line I 6; the multi-coupled array electrode group consists of a first array electrode 3, a second array electrode 4 and a third array electrode 5, and the stray current collector has a built-in zero-resistance ammeter and a high-resistance voltmeter to accurately measure the electrode potential and current of each metal wire single electrode in the above three array electrodes; the tail ends of the first array electrode 3, the second array electrode 4 and the third array electrode 5 are all connected to the test line I 6, and the other end of the test line I 6 is connected to the corresponding interface of the stray current collector 7;

[0044] The arrangement of the metal wire bundles of the first array electrode 3, the second array electrode 4 and the third array electrode 5 should be consistent, and a 4×25, 10×10 or 6×15 arrangement is selected; wherein the 4×25 array is as follows Figure 1 As shown, the 6×15 array is Figure 2 shown.

[0045] The wire bundle spacing is 0.2-0.5 mm, and the wire bundle length is 40-50 mm.

[0046] The simulated pipe section module (C) includes a test piece I 9, a test piece II 10 and a test piece III 11 of the same material and size; the test pieces I 9, II 10 and III 11 are connected in series on the insulating pipe section 8 through a test piece connecting line 12 to simulate coating defects at different positions along the pipeline; the test piece I 9 is connected to the corresponding interface of the stray current collector 7 through a test line II 13;

[0047] The test pieces I 9, II 10 and III 11 are encapsulated with epoxy resin, leaving 1 to 6.5 cm in the middle of the upper surface. 2 Exposed area, made of X65, X70 or X80 pipe steel;

[0048] The stray current applying module (D) comprises a DC source 14, both ends of which are connected to a titanium mesh electrode 16 via a wire 15, so as to simulate on-site stray currents and select to apply output signals of different magnitudes to simulate stray current interferences of different intensities;

[0049] The cathodic protection module (E) includes a power supply 17, which provides cathodic protection for a pipeline stray current detection device based on a multi-coupled array electrode. The power supply 17 is connected to three electrodes through connecting wires, specifically: a working electrode connecting wire 18 is connected to a test piece III11, a counter electrode connecting wire 19 is connected to a counter electrode 20, and a reference electrode connecting wire 21 is connected to a reference electrode 22; the power supply 17 is a constant potential meter or an electrochemical workstation; the counter electrode 20 is a titanium mesh electrode or a platinum electrode; and the reference electrode 22 is a saturated Cu / CuSO4 electrode or a saturated calomel electrode.

[0050] Example 2

[0051] The pipeline stray current detection device based on the multi-coupling array electrode described in the embodiment is used to perform stray current interference detection, which specifically includes the following steps:

[0052] ① Use the test piece connecting wire 12 to connect the test piece I 9, the test piece II 10 and the test piece III 11, leaving 1 to 6.5 cm for fixing 2 After the exposed area is sealed with epoxy resin for later use, all the connection points must be insulated; a test medium 2 with a height of about 2 to 3 cm is laid in the box, and the insulating pipe section 8 is placed on the test medium 2, and then the three test pieces of test piece I 9, test piece II 10 and test piece III 11 are placed on the insulating pipe section 8, ensuring that the three test pieces are at the same height;

[0053] ② The three array electrodes are buried horizontally on the sides of the three test pieces respectively, so that the electrode surfaces do not touch but are as close as possible to the exposed parts of the test pieces. The test lines of the test pieces and array electrodes are connected to the corresponding interfaces of the stray current collector respectively;

[0054] The three array electrodes are a first array electrode 3, a second array electrode 4 and a third array electrode 5;

[0055] Two titanium mesh electrodes 16 are buried at both ends of the insulating pipe section 8, and the center height of the titanium mesh electrode 16 is kept consistent with that of the three test pieces as much as possible; the titanium mesh electrode wire 15 is connected to both ends of the DC source 14;

[0056] ③ On the other side of the three test pieces, i.e., the side opposite to the array electrode, a reference electrode 22 and a counter electrode 20 are respectively buried, the center point height of the counter electrode 20 is as consistent as possible with the test piece height, and the tip of the reference electrode 22 is as close to the test piece as possible, but not touching it; the power supply 17 is connected to the corresponding electrodes through three-electrode test lines; the power supply 17 is a constant potential instrument or an electrochemical workstation;

[0057] ④ Continue to add experimental medium 2 until the test piece and array electrodes are completely covered. The height of the medium added should be at least 5 cm higher than the horizontal position of the test piece. Do not form voids when adding the experimental medium and compact it as much as possible.

[0058] ⑤ Turn on the power supply 17 to provide cathodic protection, under-protection or over-protection for the test piece according to the test requirements; turn on the DC source 14 to provide simulated stray current interference for the test piece, and the stray current intensity can be adjusted according to the test requirements; turn on the stray current collector 7, and the built-in zero-resistance ammeter and high-resistance voltmeter of the instrument immediately start measuring, accurately measuring the electrode potential and current of each metal wire single electrode of the three array electrodes;

[0059] ⑥ Export the test data and use Origin drawing software to display the surface potential and current distribution of the array electrode in three dimensions. By coupling the positive and negative potential and current collected at the location of the array electrode, the cathode or anode current can be judged, and the corrosion conditions of different parts of the pipeline can be further judged. The corrosion types of different locations of the pipeline under the interference of stray current can be identified. The potential distribution can also be used as a basis for the effectiveness of cathodic protection;

[0060] When a positive potential is collected and the current is positive, it is judged to be a cathode current; when a negative potential is collected and the current is negative, it is judged to be an anode current; the anode current means that relatively more serious corrosion occurs in this area on the surface of the array electrode.

[0061] The size of the test piece of the present invention can be 1.5 to 7.5 cm 2 Select within the range.

[0062] In the pipeline stray current detection device using three 25-row and 4-column multi-coupled array electrodes, under the interference of OCP and OCP+10mV stray current, three exposed areas of 1cm in the soil were 2 The average distribution of electrode current density at different positions of X65 steel specimens is shown in Figure 2. Figure 5 For OCP, Figure 6It is OCP+10mV stray current interference. Figure 5 and Figure 6 In the figure, with the bright ring as the boundary, the upper area is the anodic current and the lower area is the cathodic current. It can be seen that after applying 10mV stray current interference, the anodic current is collected on the surface of the sample, indicating that stray current corrosion occurs in this area.

Claims

1. A pipeline stray current detection device based on multi-coupled array electrodes, characterized in that: It consists of an experimental box (A), a stray current test module (B), a simulated pipe section module (C), a stray current application module (D) and a cathodic protection module (E); The experimental box (A) comprises a rectangular box (1) without a cover, the interior of the rectangular box (1) is filled with an experimental medium (2), the material of the rectangular box (1) is organic glass, polytetrafluoroethylene material or polyvinyl chloride material; the experimental medium (2) is soil or sand; The stray current test module (B) comprises a multi-coupled array electrode group, a stray current collector (7) and a test line I (6); the multi-coupled array electrode group comprises a first array electrode (3), a second array electrode (4) and a third array electrode (5); the stray current collector has a built-in zero-resistance ammeter and a high-resistance voltmeter to accurately measure the electrode potential and current of each metal wire single electrode in the three array electrodes; the tail ends of the first array electrode (3), the second array electrode (4) and the third array electrode (5) are all connected to the test line I (6), and the other end of the test line I (6) is connected to the corresponding interface of the stray current collector (7); The metal wire bundles of the first array electrode (3), the second array electrode (4) and the third array electrode (5) are arranged in a 4×25, 10×10 or 6×15 arrangement; The simulated pipe section module (C) comprises a test piece I (9), a test piece II (10) and a test piece III (11) of the same material and size; the test pieces I (9), II (10) and III (11) are connected in series on the insulating pipe section (8) via a test piece connecting line (12) to simulate coating defects at different positions along the pipeline; the test piece I (9) is connected to the corresponding interface of the stray current collector (7) via a test line II (13); The test pieces I (9), II (10) and III (11) are encapsulated with epoxy resin, leaving a 1-6.5 cm gap in the middle of the upper surface. 2 Exposure; The stray current applying module (D) comprises a direct current source (14), both ends of the direct current source (14) are connected to titanium mesh electrodes (16) via wires (15), simulating on-site stray currents, and selectively applying output signals of different magnitudes to simulate stray current interferences of different intensities; The cathodic protection module (E) comprises a power supply (17) for providing cathodic protection for a pipeline stray current detection device based on a multi-coupled array electrode. The power supply (17) is connected to three electrodes via connecting wires. Specifically, a working electrode connecting wire (18) is connected to the test piece III (11), a counter electrode connecting wire (19) is connected to the counter electrode (20), and a reference electrode connecting wire (21) is connected to the reference electrode (22).

2. According to claim 1, a pipeline stray current detection device based on multi-coupled array electrodes is characterized in that: The power source (17) is a constant potential instrument or an electrochemical workstation.

3. The pipeline stray current detection device based on multi-coupling array electrodes according to claim 1 is characterized in that: The counter electrode (20) is a titanium mesh electrode or a platinum electrode.

4. The pipeline stray current detection device based on multi-coupling array electrodes according to claim 1 is characterized in that: The reference electrode (22) is a saturated Cu / CuSO4 electrode or a saturated calomel electrode.

5. The pipeline stray current detection device based on multi-coupling array electrodes according to claim 1 is characterized in that: The material of the test piece I (9), the test piece II (10) and the test piece III (11) is X65, X70 or X80 grade pipeline steel.

6. A method for testing stray current interference using the pipeline stray current detection device based on multiple coupling array electrodes as described in claim 1, characterized in that: The following steps are involved: ① Use the test piece connecting wire (12) to connect the test piece I (9), test piece II (10) and test piece III (11), leaving a fixed space of 1~6.5cm 2 The exposed area is then sealed with epoxy resin for later use, and all connection points must be insulated; a 2-3 cm high test medium (2) is laid inside the box, an insulating pipe section (8) is placed on the test medium (2), and then three test pieces, test piece I (9), test piece II (10) and test piece III (11), are placed on the insulating pipe section (8), ensuring that the three test pieces are at the same height; ② The three array electrodes are buried horizontally on the sides of the three test pieces respectively, so that the electrode surfaces do not touch but are as close as possible to the exposed parts of the test pieces. The test lines of the test pieces and array electrodes are connected to the corresponding interfaces of the stray current collector respectively; The three array electrodes are a first array electrode (3), a second array electrode (4) and a third array electrode (5); Two titanium mesh electrodes (16) are buried at both ends of the insulating pipe section (8), and the center height of the titanium mesh electrodes (16) is kept consistent with that of the three test pieces as much as possible; the titanium mesh electrode wire (15) is connected to both ends of the direct current source (14); ③ On the other side of the three test pieces, i.e., the side opposite to the array electrode, a reference electrode (22) and a counter electrode (20) are respectively buried, the center point height of the counter electrode (20) is as consistent as possible with the height of the test piece, and the tip of the reference electrode (22) is as close to the test piece as possible, but not touching it; the power supply (17) is connected to the corresponding electrodes through three-electrode test lines; the power supply (17) is a constant potential instrument or an electrochemical workstation; ④ Continue to add experimental medium (2) until the test piece and array electrodes are completely covered. The height of the medium added should be at least 5 cm higher than the horizontal position of the test piece. Do not form voids when adding the experimental medium and compact it as much as possible. ⑤ Turn on the power supply (17) to provide cathodic protection, under-protection or over-protection for the test piece according to the test requirements; turn on the DC source (14) to provide simulated stray current interference for the test piece, and adjust the stray current intensity according to the test requirements; The stray current collector (7) is turned on, and the zero-resistance ammeter and high-resistance voltmeter built into the instrument immediately start measuring, accurately measuring the electrode potential and current of each metal wire single electrode of the three array electrodes; ⑥ Export the test data and use the drawing software to display the surface potential and current distribution of the array electrode in three dimensions. Determine the cathode or anode current by coupling the positive and negative potential and current collected at the location of the array electrode, further determine the corrosion conditions of different parts of the pipeline, and identify the corrosion types at different locations of the pipeline under the interference of stray current.

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