Research On Transient Electromagnetic Corrosion Detection Method Of Buried Metal Pipeline

The metal pipeline is trapped in the soil environment because it is buried underground.There will be a series of chemical and electrochemical corrosion reactions between the complex soil environment and the pipe body.The long-term impact of corrosion will cause serious corrosion aging phenomenon of the pipeline.It is very important to study the trenchless corrosion detection of the metal pipeline for the evaluation and maintenance of the pipeline corrosion.Transient electromagnetic method(TEM)is a relatively new nondestructive testing method for detecting buried metal pipelines,which has the advantages of no excavation,in-service testing,simple and easy operation,little impact by the terrain and environment,etc.in this paper,it is of great theoretical significance and practical value to study the mode of detection device based on the analysis of influencing factors of TEM for buried metal pipelines.This paper introduces several commonly used types of transient electromagnetic working devices,aiming at the selection of the actual completion device type of the buried metal pipeline project;through the analysis of the characteristics of the transient electromagnetic detection voltage signal of the buried metal pipeline,the extraction and analysis method of the related characteristics of the induced voltage signal curve wall thickness is proposed.The numerical simulation model of transient electromagnetic detection of buried metal pipeline is established by using ANSYS finite element simulation software.The wall thickness characteristics of induction voltage signal are extracted in Cartesian coordinate system and single logarithmic coordinate system respectively.The signal processing method and slope characteristics extraction method used in this paper are determined to evaluate the corrosion degree of pipeline.The analysis of induced voltage signals of different wall thickness pipes shows that different wall thickness pipes correspond to different slope eigenvalues,and there is a function between wall thickness and slope.The numerical simulation of buried metal pipelines with different buried depth,diameter,physical parameters of soil and transmission medium was carried out,and the influence of various factors on induced voltage signal was analyzed.The single variable method is used to test the corrosivity of the pipeline with different wall thickness and lift off height by using the transient electromagnetic detection system,which verifies the correctness of the numerical simulation calculation of the buried pipeline and the effectiveness of the corrosivity detection method.