Test method and application of pipeline cathodic protection potential check sheet
Time:
Jan 17,2022
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According to relevant standards, the evaluation of cathodic protection effect of steel buried pipelines shall be based on power failure.The field test usually uses the synchronous interrupt method, but it does not apply to the failure to synchronize the cathode in the interrupt tube.Protection current, as well as the pipe section disturbed by stray current. Cathodic protection potential check sheet can solve this problem,By simulating the leakage point of the pipeline anti-corrosion layer, the instantaneous disconnection potential of the inspection sheet is used to approximate the pipeline power-off potential.Measurements. This paper introduces in detail the scope of application, design, installation and testing of pipeline cathodic protection potential inspection sheet.
and analysis, etc., through specific implementation cases to clarify the standardization of data records, and verify the test method.lay a practical foundation for the popularization and application of this method.
Steel buried pipelines are usually protected by a combination of anti-corrosion coating and cathodic protection.Layer as the first layer of fortress, the use of its good insulation, anti-permeability and mechanical properties to achieve anti-corrosion purposes;As a second line of defense, the cathodic protection system can be used to protect the corrosion protection layer from damage or micropores.Cathodic polarization is applied to the pipe to slow down or eliminate pipe wall corrosion. According to GB/T 21448-2008 "buried steel".Quality pipeline cathodic protection technical specifications, pipeline cathodic protection effect evaluation should use the power-off potential index, on-site.
The GPS synchronous interruption method is usually used in the test, but it is not suitable for the failure to synchronously interrupt the cathode protection in the pipe.flow, and pipe sections disturbed by stray currents..
Cathodic protection potential inspection sheet can solve this problem, by simulating the pipeline anti-corrosion layer leakage,The instantaneous disconnection potential of the inspection sheet is used to realize the measurement of the approximate pipeline disconnection potential. Cathodic protection potential check sheetIt is a check piece used to simulate the potential after cathodic polarization of the pipeline under investigation, which is buried at the pipeline test point and inspected.The part of the inspection sheet is exposed, and the other part is provided with anti-corrosion coating. The embedded state and material of the inspection sheet are the same as those of the pipeline.The cable is connected to the pipeline, so that the exposed part of the inspection sheet simulates a leakage point of the anti-corrosion layer of the pipeline.
When the pipeline is in the cathodic protection state, the pipeline is polarized by the protection current, and the inspection sheet is also polarizedTo the same extent as the pipeline, simply measure the instantaneous disconnection potential of the inspection sheet to represent the disconnection of the pipeline measurement point.Electrical potential. NACE SP0502 -2010 "Direct Evaluation Method for External Corrosion of Pipelines" considers that the power failure of the inspection sheetThe potential is similar to the cathodic protection potential at the leakage point of the pipeline anti-corrosion layer, which can evaluate the cathodic protection effect of the pipeline.
1 Scope of application
Cathodic protection potential inspection sheet can evaluate the cathodic protection effect of buried steel pipeline, as long as it can.The inspection sheet can be applied by connecting it to the pipeline, especially in the following cases where the synchronous interruption method is limited:
(1) The cathodic protection current provided by multiple potentiostat in the protection system cannot be interrupted synchronously;
(2) There is an external cathodic protection system influence, it is difficult to interrupt the constant potential of the protection system.Instrument;
(3) There is a directly connected, uninterruptible sacrificial anode;
(4) the existence of DC stray current influence, resulting in the power-off potential can not represent the cathodic protectionposition;
(5) the use of pipeline cathodic polarization attenuation or polarization formation to judge the pipeline cathodic protection effect;
(6) There are multiple pipelines in the public corridor, which cause interference with each other.
2 Inspection sheet design
The material of the cathodic protection potential check sheet shall be the same as that of the test pipe, and the exposed area of the check sheet shall beIt should be close to the maximum defect of the anti-corrosion coating that may occur in the test pipe section, and the exposed area should be 10~100 cm2,3PEThe anti-corrosion layer and epoxy coating should be 10cm, and the asphalt anti-corrosion layer should be 50cm '. The exposed surface shall be located at the inspection plate width.The middle part of the surface is covered with a water-resistant sealing material that is easy to remove, usually with oil-based paint orPE set.
The surface of the inspection sheet shall be kept metallic luster and free of rust; the inspection sheet shall be firmly connected with the cable and connectedThe connection resistance should be as small as possible, and the connection should be free of rust and sealed. If necessary, the inspection piece and the cable connection should be checked.Rust removal.
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Jiaozuo Furuixin Nonferrous Metals Co., Ltd.
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