Measurement Principle
The basic element of the AFD acquisition survey is the high-resolution Magnetic Flux Leakage (MFL) technology. The pipe wall is magnetized circumferentially to saturation level using the very latest permanent magnets.
High magnetization levels are necessary to differentiate corrosion and other critical features from typically uncritical features such as hot spots, stress and strain variations and to minimize the effects of remanent magnetization and velocity.

In a pipeline with no flaws, the magnetic flux travels undisturbed through the walls. In the presence of internal and external metal loss, the flux “leaks” out of the pipeline and is recorded by hall effect sensors, of which there can be hundreds. The sensor system and electronics developed and manufactured in-house guarantee high resolution and sensitivity with 360-degree full circumferential coverage with sensor spacing of less than 3 mm. High magnetization levels of >10 kA/m ensure the validity of the results.