In the Magnetic Flux Leakage (MFL) method, a magnetising system applies a magnetic field to the item under test. Defects or discontinuities in the item distort this applied field, producing flux leakage. Sensors measure flux leakage and a recording system stores the measurements. Flux leakage measurements are analyzed to estimate the defect geometry and severity.
MFL inspections are typically used to detect, locate, and characterize metal-loss and other anomalies in natural gas-transmission pipelines, bulk fuel storage tank floors and other petrochemical industry applications.