Buried Steel Pipeline Anticorrosion Layer Breakage Detection Method Research

Buried pipelines are important infrastructure for transporting various fluids and gases,providing necessary services and materials for urbanization and development.Buried pipelines typically require anticorrosive coatings to protect them from corrosion and damage,especially in environments with corrosive media.When the anticorrosive coating is damaged,the surface of the pipeline is easily exposed to the environment,which may cause corrosion,perforation,and leakage of the pipeline,resulting in environmental pollution.If the transported medium is flammable or explosive,it can also pose serious safety hazards.The detection of defects in buried pipeline anticorrosive coatings is a very important task,as it can identify damage to the anticorrosive coating and appropriate repair measures can be taken promptly.This thesis introduces the corrosion mechanism,protective measures and detection methods of buried steel pipelines,through the construction of buried pipeline equivalent circuit model and analytical model for simulation analysis,proposed the AC impedance test combined with dense interval potential corrosion layer damage detection method,through the buried pipeline AC impedance spectrum test and dense interval pipe ground potential inspection experiments to verify the effectiveness of the corrosion layer damage detection method,the main research work is as follows:(1)Introduced the corrosion mechanism of buried steel pipeline metals in different corrosive environments and the manifestation of corrosion,listed the common corrosion protection measures and introduced their protection principles,analyzed the causes of buried pipeline corrosion layer defects and the advantages and disadvantages of conventional detection methods.(2)The equivalent circuit model and the analytical model of the buried pipeline corrosion protection system were established based on the principles of AC impedance spectrum test and pipe ground potential test respectively,and the factors influencing the impedance characteristics of the system were analysed through the simulation of the equivalent circuit model,and the distribution pattern of the pipe potential and pipe current of the buried pipeline was analysed through the simulation of the analytical model.The distribution characteristics of the ground potential and potential gradient of the plane pipe are analysed.According to the electrical response characteristics of the model,the AC impedance test combined with the dense interval potential is proposed as the corrosion layer damage detection method.(3)Based on the distribution characteristics of surface potentials around the damaged points,a buried pipeline closely spaced potential inspection system was designed.The hardware was selected and the software was designed for the pipeline potential data acquisition device.The upper computer software was developed to realize data transmission,storage and noise reduction functions.The upper computer determines the location of the corrosion damage point by using the coordinate information of the maximum value of the denoised pipeline potential distribution curve.(4)An experimental platform for detecting and locating corrosion damage in buried pipelines was built,using a combination of AC Impedance testing and closely spaced potential testing.Differences in impedance characteristics with or without corrosion defects in the anti-corrosion layer were studied through AC Impedance Spectrum testing.The system impedance characteristics of buried pipelines were analyzed under different numbers and locations of damage and soil resistivity to explore the impact of various factors on system impedance characteristics.Then,data was collected along the pipeline surface using the closely spaced potential method.The denoising effect of empirical mode decomposition reconstruction algorithm and wavelet denoising algorithm was compared,and the location of the corrosion damage point was determined based on the denoised pipeline potential distribution curve,thus improving the accuracy of the damage point location.This thesis has 51 pictures,9 tables and 85 references.