Method for detecting corrosion of metal pipe outer wall

A technology for outer wall corrosion and pipelines, which is applied in the field of metal corrosion measurement devices, can solve the problems of quantitative evaluation and indirect evaluation of the corrosion state of metal pipelines, and achieve the effects of simple and accurate evaluation methods, rapid detection and evaluation, and high data resolution

Inactive Publication Date: 2017-12-05
TIANJIN UNIV
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  • Summary
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  • Claims
  • Application Information

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Problems solved by technology

At present, domestic evaluation methods for the corrosion resistance of metal pipelines are limited to monitoring the deformation of the pipeline and the use status of the outer coating, or using non-destructive testing methods to detect the damage location and damage degree of the pipeline whose outer wall has been damaged. Indirect evaluation of the overall corrosion status of metal pipelines can be made by using parameters such as changes in pipeline surface morphology, and it is impossible to quantitatively evaluate the corrosion status of metal pipelines under service conditions
Based on the principle of electrochemical measurement, the on-line rapid detection and evaluation of the corrosion state of the outer wall of the metal pipeline and the electrochemical measurement test device and evaluation method applicable to the outer wall of various specifications of metal pipelines have not been used in China.

Method used

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  • Method for detecting corrosion of metal pipe outer wall
  • Method for detecting corrosion of metal pipe outer wall
  • Method for detecting corrosion of metal pipe outer wall

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0066] Utilize AutoLab 302N electrochemical workstation and the test device developed to carry out electrochemical impedance test, the test sample is X65 pipeline steel, the outer wall of the sample is evenly coated with epoxy resin coating, and the test solution is 3.5wt% sodium chloride aqueous solution ( Simulated seawater), the sponge is filled with the test solution and stuffed into the bottom of the test device, the test temperature is 25°C, the test period is 50 days, the results are as follows Figure 8 shown.

[0067] Soaking time until the 10th day, the measured impedance complex plane is still in the shape of a single semicircle, and it can be inferred from the radius of the capacitive reactance arc that the measured inner wall surface has a higher coating resistance (50MΩ*cm2), It shows good corrosion resistance. In order to further confirm the accuracy of the experimental data, the sample was placed under a KEYENCE VHX-2000 full depth microscope for magnification...

Embodiment 2

[0070] Utilize AutoLab 302N electrochemical workstation and the test device developed to carry out electrochemical impedance test, the test sample is X65 pipeline steel, the outer wall of the sample is evenly coated with epoxy resin coating, and the test solution is 3.5wt% sodium chloride aqueous solution ( Simulated seawater), the sponge was filled with the test solution and stuffed into the bottom of the test device, the test temperature was 25°C, and the test time was the 140th and 200th day of immersion respectively. The results are as follows Figure 11 shown.

[0071] On the 200th day of immersion, the measured impedance complex plane began to show the characteristics of three time constants of double capacitive reactance arc + diffusion impedance, and the radius of the capacitive reactance arc decreased significantly (30KΩ*cm2) compared with the initial soaking period, indicating that the solution had penetrated. When the overcoat reaches the surface of the metal substr...

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Abstract

The invention relates to a method for detecting the corrosion of a metal pipe outer wall. The apparatus comprises a disc-shaped cover plate, a reference electrode column, an auxiliary electrode and a circular base, wherein the center position of the disc-shaped cover plate is provided with a cover plate middle hole, the outer side of the small disc of the disc-shaped cover plate is provided with threads, the reference electrode column comprises an upper part and a lower part, the upper part comprises a reference electrode wiring column, a connection column and a silver chloride wire, the lower part comprises a fastening screw pipe and a glass pipe, the connection column of the upper part is sleeved on the outer side of the glass pipe of the lower part, the silver chloride wire in the connection column extends to the bottom end of the glass pipe, the platinum sheet of the auxiliary electrode is arranged below the small disc of the disc-shaped cover plate, and an annular magnet is arranged inside the circular base and is used for adsorbing the whole apparatus on the surface of the experimental metal. According to the present invention, the operation of the method is convenient and rapid, and the damage condition, the damage type and the corrosion degree of the metal pipeline outer wall coating in the service state can be rapidly determined.

Description

technical field [0001] The invention relates to a metal corrosion measuring device, in particular to a method for detecting the corrosion of the outer wall of a metal pipeline. Background technique [0002] According to a survey, the annual economic loss caused by corrosion in the world reaches 600 billion to 1.2 trillion yuan, accounting for 2%-4% of the gross national product of each country. Especially for water conservancy or oil and gas pipelines, the safety of pipelines during their operation is of great significance. There are many factors that affect the service life of metal pipelines, such as pipeline working pressure, processing materials, third-party damage, metal corrosion, coating cracks and other factors will shorten the service life of pipelines. Among them, corrosion factors have the most serious influence on the service life of pipelines. [0003] The environments that cause metal corrosion vary greatly, and even the same material has different corrosion ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N17/02G01N17/00
CPCG01N17/006G01N17/02
Inventor 王吉会李秋实
Owner TIANJIN UNIV
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