A Method For Identifying Inclined Defects By Using Magnetic Flux Leakage Spectral Envelope Detection

Magnetic flux leakage (MFL) detection, as a non-destructive testing method for detecting the leakage magnetic field inside and outside the pipeline, is one of the most commonly used methods in pipeline inspection. This paper analyzes and gains the characteristics of the inclined defects MFL detection signal by using the Finite Element Method (FEM), and compares with the MFL detection signal of the traditional defect to get the relationship between the signal intensity and the slope of the inclined defects, which can explain the reason that the inclined defects easy to be omitted in the engineering. In this paper, the MFL signals characteristics of the inclined defects are investigated in the frequency domain, and the relationship between the cutoff frequency and the slope angle of the inclined defects is revealed. A method using the spectral envelope is proposed to solve the problem of detecting the inclined defects. Furthermore, a corresponding experiment is performed, and the method proposed in this paper is verified.