Magnetic Flux Leakage (MFL) uses a powerful magnets to magnetize the conductive material under test where a magnetic field is created around defects like corrosion or material loss. The magnetic field induced in the part saturates it until it can no longer hold any more flux. The flux overflows and leaks out of the pipe wall and strategically placed sensors can accurately measure the three-dimensional vector of the leakage field. Because magnetic flux leakage is a vector and that a sensor can only measure one direction, any given probe must have three sensors to accurately measure the axial, radial, and circumferential components of an MFL signal.
Advantages Of MFL
- One of the few methods used to inspect finned tubes
- Can be used on all ferromagnetic materials
- Good sensitivity to pitting
- High-speed inspection