Theoretical study on the characteristics of self-magnetic flux leakage signals from pipeline defects

摘要

The metal magnetic memory (MMM) testing technique has been extensively applied in the detection of ferromagnetic pipeline defects. However, this technique usually only finds possible locations for pipeline defects and cannot quantify defect characteristics. In this paper, a self-magnetic flux leakage (SMFL) model of an elliptical cylinder defect is established based on the theory of magnetic charge, which can simulate SMFL for different defects and capture the corresponding SMFL characteristics. For hole corrosion, which is a common problem in pipelines, quantitative relationships between the SMFL and the influence of factors such as defect length, defect depth and lift-off value of the sensor are discussed through the established model. Experimental results show that the model established in this paper can successfully calculate the SMFL of pipeline defects. In particular, the proposed model can roughly estimate the defect parameters based on the received SMFL signals, which is of great significance for the quantitative detection of pipeline defects.