Study on the Lowest Spatial Resolution of Magnetic Flux Leakage Testing for Weld Cracks

In this study, the analysis of the lowest spatial resolution for measuring weld cracks based on the magnetic flux leakage (MFL) test method was developed. MFL detection is a widely used method of pipeline nondestructive testing. The spatial resolution of the MFL sensors influences the data amount and detection accuracy. The magneto-optical detection technique can be used to solve the problem of insufficient spatial resolution, but the amount of data is very large and redundant. Using the lowest spatial resolution with ensuring accuracy can reduce the amount of data and decrease the time cost of analyzing data. A girth weld crack is a common and complex defect that occurs in pipelines, and high spatial resolution is required to ensure its detection accuracy. In this study, the MFL of weld cracks and its influencing factors were investigated. Based on the frequency domain analysis, the lowest spatial resolution was obtained, which was verified by experiments.