The Remote Field Eddy Current (RFEC) tube inspection technique is used to inspect ferromagnetic pipes and tubes from the inside.The basic probe is made with one exciter coil and two receiver coils.Two main fields are present, coupling the energy between the exciter and the receivers:

The direct field is centered around the exciter coil and is rapidly attenuated relative to the distance down the tube.

The indirect field is discussed outward through the tube wall, propagates along the tube axis and is then rediffused back through the tube wall.

The zone in which the indirect field is dominant is called the remote field zone. This zone is present at a distance greater than two tube diameters.

Advantage

Only ferrous tubes can be inspected.
Detects discontinuities such as corrosion, erosion, wear, pitting and baffles cuts.
Inspection speed 0 .3m/s. Able to inspect around 400 tubes per shift.