Application Of Low Frequency Electromagnetic Technology In Pipeline Defect Detection

Pipeline is currently an important tool for the transport of gas or liquid and the length ofgas and oil pipeline is increasing more and more. Because of the high-speed development ofpipeline transportation industry, people pay more and more attention to the safety of thepipeline operation. Once the explosion of pipeline occurred, it will bring great loss to thesafety of people’s lives and property and serious consequences on society and the environment.People is focusing on the effective nondestructive detection method for pipelines. Lowfrequency electromagnetic technique is mentioned in order to improve the detection accuracyof the pipeline. It is a new technology of magnetic flux leakage testing using low frequencyAC excitation.This paper systematically studied the principle and the detection method of lowfrequency electromagnetic technique and using finite element analysis method on COMSOLsimulation software to establish the simulation model of low frequency electromagneticdetection and three dimensional simulating calculation. Mainly studied the changing situationof leakage magnetic field at the presence of defects or not. Studied the changing rule aboutpipeline leakage magnetic field of magnetic induction intensity under different size of defect.Analyzed the changing situation about leakage magnetic field of magnetic induction intensityof the pipeline is at the changing of incentive intensity and excitation frequency of excitationsignal. Studied The distribution curve of magnetic induction intensity under different lift-offvalue. The changing rule of the magnetic induction intensity in different test conditions isanalyzed comprehensively. This article also make the experiment device of low frequencyelectromagnetic detection system and the simulation of pipeline defect detection experimentsare carried. It also contrast detection signal between the artificial processing defect andwithout defects respectively. The experiment is carried at the defect depth of2mm,4mm and6mm and the excitation frequency of5Hz,10Hz,15Hz,20Hz; As well as in the case ofchange detection coil lift-off value to get the changing rule of the detection signal.Simulation and experiment results show that the detection signal is significantly greaterwhere the defect exists than the situation without defect.Along with the increasing of thedefect depth and frequency of excitation signal, the detecting coil electrical signal amplitude is more and more bigger. With the increasing of lift-off value, the amplitude of signal is moreand more small. Electrical signals can characterize the size of the defect. It shows that thisdetection technology is obvious which can carry on the detection of pipeline defect byanalyzing the experimental results. In a word, it is a feasible nondestructive testing method.