Pipeline anti-corrosion layer detection method adopting dense interval potentiometry

Abstract

The invention provides a pipeline anti-corrosion layer detection method adopting a dense interval potential method, and relates to the field of pipeline anti-corrosion layer detection, which is characterized by comprising the following steps of: 1, setting a cathode protection system: for a pipeline adopting forced current potential cathode protection, before data acquisition, erecting satellite synchronous on-off devices at all constant potential positions for protecting the pipeline, and the satellite synchronization function is utilized to ensure accurate time control of the on-off device. The device and the method have the advantages that the millivolt-level signal acquisition effect of the potential of the anticorrosive coating is achieved by integrating the high-precision reference electrode array on the underwater detection platform, the millimeter-level positioning effect of the damaged point of the anticorrosive coating is achieved by adopting a 0.2-0.5 m dense interval potential gradient measurement method, and the detection accuracy is improved. Analyzing the potential abrupt change characteristic (delta Vgt; the effect of quantitatively evaluating the damage area and severity is achieved, and the effect of continuously and rapidly scanning a long-distance pipeline is achieved through autonomous cruise detection of the underwater robot.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of pipeline coating detection, in particular to a pipeline coating detection method using close-spaced potential method. BACKGROUND

[0002] Pipeline coating detection refers to a process of evaluating the integrity, insulation performance and aging condition of the pipeline outer coating through special equipment and technical means, aiming to prevent corrosion leakage accidents and prolong the service life of the pipeline. Common methods include direct current voltage gradient, alternating current voltage gradient and multi-frequency pipeline current method, which locate the defect position by detecting the leakage signal or current attenuation of the coating damage point, and cooperate with close-spaced potential detection to evaluate the effect of cathodic protection. Modern detection technology has integrated electromagnetic induction, ultrasonic guided wave and unmanned aerial vehicle infrared imaging to realize non-contact rapid scanning. Combined with GIS system, it can generate a three-dimensional map of the health status of the coating, providing data support for pipeline maintenance in oil and gas, chemical and other industries, and effectively reducing safety and environmental risks caused by corrosion.

[0003] When the metal pipeline is in an electrolyte environment, it is prone to electrochemical corrosion. Cathodic protection system is usually used to prevent corrosion. However, once the coating is damaged, the metal directly contacts the electrolyte, which will cause a change in potential. The existing detection method cannot accurately detect the damage location and extent of the coating. SUMMARY

[0004] The purpose of the present application is to provide a pipeline coating detection method using close-spaced potential method, which solves the problem that the existing detection method cannot accurately detect the damage location and extent of the coating.

[0005] In order to achieve the above-mentioned purpose of the application, the technical solution adopted by the present application is as follows:

[0006] A pipeline coating detection method using close-spaced potential method, characterized in that it comprises the following steps: step one, cathodic protection system setting: for a pipeline using forced current potential cathodic protection, before data collection, a satellite synchronous on-off switch is erected at all constant potential points for protecting the pipeline to ensure the time control accuracy of the on-off switch by using satellite synchronization function, and the on-off period is set to 3 seconds of power-on and 1 second of power-off. For a pipeline using sacrificial anode cathodic protection, no satellite synchronous on-off switch is needed, and the protection potential is directly tested.

[0007] Step two, detection platform preparation: a high-sensitivity reference electrode (such as a saturated copper sulfate electrode) is mounted on an underwater or water surface mobile platform, which is used to sense the potential of the pipeline surface.

[0008] Step three, potential data collection: control the underwater or surface moving platform to slowly move along the surface of the pipeline or metal structure in the water body, and take potential measurements at intervals of 1-1.5 meters. During the movement, the reference electrode continuously records the potential data of the pipeline surface, forming a potential-distance curve.

[0009] Step four, data processing and analysis: by analyzing the potential-distance curve, identify the characteristics of potential changes. When the curve shows a sudden positive shift in potential (i.e., the potential becomes more positive), it is identified as a signal of coating damage. According to the amplitude and duration of the positive potential shift, the severity of the coating damage can be preliminarily judged. A larger amplitude of positive potential shift and longer duration indicate a larger area of coating damage or severe cathodic protection failure, while a smaller positive potential shift and shorter duration indicate a smaller area of coating damage or slight cathodic protection failure.

[0010] As an improvement, the reference electrode is a saturated copper sulfate electrode.

[0011] As an improvement, the on-off cycle of the on-off switch is set to 3 seconds on and 1 second off for more precise detection.

[0012] As an improvement, the interval for potential data collection is 1-1.5 meters.

[0013] As an improvement, during the potential data collection process, potential measurement data is continuously recorded, forming a potential-distance curve.

[0014] The potential data collection is operated in the control center on the shore or on the ship.

[0015] As an improvement, the detection method is used to detect the integrity of the coating and the effectiveness of the cathodic protection of the metal structure with cathodic protection in the water body.

[0016] As an improvement, during the potential data collection process, the moving platform moves at a constant speed above the pipeline in the water body.

[0017] As an improvement, during the potential data collection process, the recording frequency of potential measurement data is once per second.

[0018] The detection method is applicable to the following application scenarios for metal structures: 1. Submerged metal structures: various metal structures that are immersed in water for a long time; 2. Subsoil buried metal structures: metal structures buried in underwater soil environments; 3. Artificial structure erected metal structures: metal structures erected in underwater artificial structures.

[0019] The beneficial effects of the present application are: by integrating a high-precision reference electrode array on the underwater detection platform, the millivolt-level signal collection effect of the anticorrosion layer potential is achieved, by using the 0.2-0.5 meter dense interval potential gradient measurement method, the effect of positioning the millimeter level anticorrosion layer damage point is achieved, by analyzing the potential mutation characteristics (ΔV>50mV) of the cathodic protection current at the defect, the effect of quantitatively evaluating the damage area and severity is achieved, and by the autonomous cruise detection of the underwater robot, the effect of long-distance pipeline continuous rapid scanning is achieved. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 The technical roadmap of the pipeline anticorrosion layer detection method using dense interval potential method of the present application. DETAILED DESCRIPTION

[0021] In order to make the content of the present application easier to be clearly understood, the technical solutions in the embodiments of the present application will be clearly and completely described below in combination with the drawings in the embodiments of the present application. The same parts are denoted by the same reference numerals. It should be noted that the words "front", "back", "left", "right", "up" and "down" used in the following description refer to the directions in the drawings, and the words "inner" and "outer" refer to the directions towards or away from the geometric center of a particular part.

[0022] As shown in Figure 1 A pipeline anticorrosion layer detection method using dense interval potential method, characterized in that it comprises the following steps: step one, cathodic protection system setting: for the pipeline using forced current potential cathodic protection, before data collection, satellite synchronous on-off switches are erected at all constant potentials for protecting the pipeline, the satellite synchronous function is used to ensure the time control accuracy of the on-off switch, the on-off period is set to 3 seconds of power-on and 1 second of power-off, for the pipeline using sacrificial anode cathodic protection, satellite synchronous on-off switches are not needed, and the protection potential is directly tested;

[0023] Step two, detection platform preparation: a high-sensitivity reference electrode (such as a saturated copper sulfate electrode) is carried on an underwater or water surface moving platform, and the reference electrode is used to sense the potential of the pipeline surface.

[0024] Step three, potential data collection: control the underwater or water surface moving platform to slowly move along the surface of the pipeline or metal structure in the water body, and perform potential measurement at an interval of 1 meter to 1.5 meters, and in the moving process, the reference electrode continuously records the potential data of the pipeline surface, and forms a potential curve relative to the distance;

[0025] Step four, data processing and analysis: by analyzing the curve of potential versus distance, the characteristics of potential change are identified, when the curve appears a sudden positive shift of potential (i.e. the potential becomes more positive), it is identified as a signal of coating damage, according to the amplitude and duration of the positive shift of potential, the severity of coating damage is preliminarily judged, a larger amplitude of positive shift of potential and longer duration represent a larger area of coating damage or serious cathodic protection failure, a smaller positive shift of potential and shorter duration represent a smaller coating damage or slight cathodic protection failure.

[0026] In the formula, the reference electrode is a saturated copper sulfate electrode.

[0027] In addition, the on-off cycle of the on-off switch is set to 3 seconds on and 1 second off, so as to carry out more fine detection.

[0028] Secondly, the interval of potential data collection is 1-1.5 meters.

[0029] In addition, during the potential data collection process, the potential measurement data is continuously recorded to form a curve of potential versus distance.

[0030] In other words, the potential data collection is operated in the control center on the shore or on the ship.

[0031] In addition, the detection method is used to detect the coating integrity and cathodic protection effectiveness of the metal structure with cathodic protection in the water body.

[0032] Secondly, during the potential data collection process, the mobile platform moves above the pipeline in the water body at a constant speed.

[0033] In addition, during the potential data collection process, the recording frequency of the potential measurement data is once per second.

[0034] The detection method is suitable for the following application scenarios of metal structures: one, underwater submerged metal structures: various metal structures immersed in water for a long time; two, underwater soil buried metal structures: metal structures buried in underwater soil environment; three, underwater artificial structure erected metal structures: metal structures erected in underwater artificial structures.

[0035] In use, in the process of close-interval potential detection, first, according to the type of the metal structure to be detected (such as underwater immersion type, soil burying type or artificial structure erection type), a high-sensitivity reference electrode (such as a saturated copper sulfate electrode) is carried on an underwater or water surface mobile platform; for a pipeline adopting forced current cathodic protection, satellite synchronous on-off devices are needed to be erected at all constant potentials, and the on-off period is set to 3 seconds of power-on and 1 second of power-off, so as to ensure the accuracy of time control; for a pipeline adopting a sacrificial anode cathodic protection, satellite synchronous on-off devices are not needed to be used, and the protection potential can be directly tested; then, the mobile platform is operated at a control center on the shore or on a ship, so that the mobile platform slowly moves along the surface of the pipeline or the metal structure at a fixed interval of 1 to 1.5 meters, and potential data are continuously recorded through the reference electrode to form a potential-distance curve; through analysis of the curve, if the potential suddenly shifts positively (i.e., the potential becomes more positive), it indicates that there may be coating damage or insufficient cathodic protection at the position, and according to the amplitude and duration of the positive potential shift, the severity of the damage can be preliminarily judged.

[0036] The above only describes the preferred embodiments of the present application and is not used to limit the present application. Any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A pipeline anti-corrosion layer detection method using a close-interval potential method, characterized in that: The following steps are involved: Step 1: Cathodic protection system setup: For pipelines using forced current potential cathodic protection, before data collection, satellite-synchronized switches are installed at all constant potential points protecting the pipeline. The satellite synchronization function is used to ensure accurate time control of the switches. The on-off cycle is set to 3 seconds for power on and 1 second for power off. For pipelines using sacrificial anode cathodic protection, there is no need to use satellite-synchronized switches; the protection potential can be directly tested. Step 2: Prepare the detection platform: Place a highly sensitive reference electrode (such as a saturated copper sulfate electrode) on an underwater or surface mobile platform. This reference electrode is used to sense the potential on the pipeline surface. Step 3: Potential data acquisition: Control the underwater or surface mobile platform to slowly move along the surface of the pipeline or metal structure in the water body, and measure the potential at intervals of 1 to 1.5 meters. During the movement, the reference electrode continuously records the potential data of the pipeline surface, forming a curve of potential versus distance; Step 4. Data processing and analysis: By analyzing the curve of potential relative to distance, the characteristics of potential change are identified. When a sudden positive potential shift appears on the curve (i.e., the potential becomes more positive), it is identified as a signal of anti-corrosion layer damage. According to the amplitude and continuous distance of the potential positive shift, the severity of the anti-corrosion layer damage is preliminarily judged. A larger positive potential shift that lasts for a longer distance indicates that there may be a larger area of ​​anti-corrosion layer damage or serious cathodic protection failure. A smaller positive potential shift that lasts for a shorter distance indicates that there may be a smaller anti-corrosion layer damage or slight cathodic protection failure.

2. The pipeline anti-corrosion layer detection method using the close interval potential method according to claim 1 is characterized in that: The reference electrode is a saturated copper sulfate electrode.

3. The pipeline anti-corrosion layer detection method using the close interval potential method according to claim 1 is characterized in that: The on-off cycle of the switch is set to 3 seconds for power on and 1 second for power off, so as to perform more precise detection.

4. The pipeline anti-corrosion layer detection method using the close interval potential method according to claim 1 is characterized in that: The potential data is collected at an interval of 1 meter to 1.5 meters.

5. The pipeline anti-corrosion layer detection method using the close interval potential method according to claim 4 is characterized in that: During the potential data acquisition process, potential measurement data are continuously recorded to form a curve of potential versus distance.

6. The pipeline anti-corrosion layer detection method using the close interval potential method according to claim 1 is characterized in that: The detection method is used to detect the integrity of the anti-corrosion layer of a metal structure with cathodic protection in water and the effectiveness of the cathodic protection.

7. The pipeline anti-corrosion layer detection method using the close interval potential method according to claim 5 is characterized in that: During the potential data collection process, the mobile platform moves at a constant speed above the pipe in the water body.

8. The pipeline anti-corrosion layer detection method using the close interval potential method according to claim 7 is characterized in that: During the potential data acquisition process, the frequency of recording the potential measurement data is once per second.

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