One of the most commonly used ILI methods is magnetic flux leakage (MFL), which uses powerful magnets to magnetize (induce a magnetic flux) the pipeline wall. Sensors on the ILI detect problems in the pipeline wall – such as corrosion or missing pieces of the wall – through “leaks” in the magnetic field. For example, a section of a pipeline could be recessed due to corrosion, which the ILI magnetic field would enter, or “leak” into. Data about the leak is relayed to external equipment, which maps the exact location of the problem.