Study On The Interference Factors Of Buried Metal Pipeline Detection Based On Weak Magnetic Testing Technology

A complex geographical environment of buried pipeline,conventional Nondestructive testing method for excavated pipeline require excavation cost is too high,too long,so that the integrity of buried pipeline to conduct a comprehensive management has been important and difficult non-destructive testing industry.With the increase of pipeline service time,it is affected by land subsidence,construction defects,external electrochemical corrosion,and internal media corrosion,leading to corrosion and perforation,which leads to oil and gas leakage accidents,resulting in economic losses and environmental pollution.A field weakening detection method developed for the corrosion detection of buried pipelines can be used to quickly and effectively detect the corrosion of the pipe body,which has attracted widespread attention in the non-destructive testing community.However,due to the fact that the actual situation on the scene is complex,the detection effect is often interfered by various factors,resulting in the inability to correctly determine the existence of defects.Firstly,some basic characteristics of the magnetic field and material magnetization of the field weakening detection theory are introduced,and the basic theory is combined to describe the principle of field weakening detection.Secondly,several sets of experiments were designed for several common interference factors,such as changes in pipeline depth,unknown cross-tubes,changes in underground parallel pipe spacing,and unknown underground metal objects.For the change of the magnetic field caused by the change of pipeline depth,the formula for calculating the relationship between the magnetic field and the depth of the buried pipe is fitted.For an unknown crossover tube,the presence of a crossover tube will result in a change in the magnetic field,and the crossing position,the upper crossover,or the lower crossover will also affect the magnetic field of the detected tube to a different extent.For the parallel pipe,different parallel angles and parallel distances are designed.According to the maximum deviation angle of the parallel pipe in the project,the relationship between the deviation angle and the magnetic induction intensity is obtained,so that some misalignment caused by magnetic anomaly can be ruled out.Unknown for subterranean metal objects,using the standard orthogonal basis function decomposition algorithm in the field of geophysical exploration,the presence of a metal object near the pipeline is simulated,and the resultsof this algorithm can improve the signal to noise ratio.In order to determine the validity of the experimental results,the experimental conclusions were applied to the engineering practice.The abnormal signals found at the two locations gave basic judgments,and the results were verified by excavation.The excavation verification results are consistent with the results judged by the experimental conclusions,thus demonstrating the feasibility and effectiveness of the elimination method of interference factors,and can achieve good results in engineering applications.