The alternating field Magnetic Flux Leakage method concentrates the magnetic flux on the material surface and is thus particularly sensitive for the detection of small surface defects from approx. 100 µm depth.
Two rotating yokes produce the magnetic flux; the integrated magnetic field sensors capture the flux leakage occurring at the defective locations.
The constant field Magnetic Flux Leakage method magnetises the complete material cross section. Defects on the inside and outside tube surface can thus be detected. The detection of inner defects decreases as the wall thickness increases.
The magnetic flux is structured circularly with two rotating yokes for the detection of longitudinally oriented defects. The occurring flux leakage at the defective locations is captured with rotating magnetic field sensors.
The magnetic flux is produced by two stationary encircling coils arranged in the longitudinal direction for the detection of transverse-oriented defects. Several stationary magnetic field sensors on the circumference capture the occurring flux leakage.