The signals obtained with RFT are very similar to
those obtained with conventional eddy current testing. When all
the proper conditions are met, changes in the phase of the receiver
signal with respect to the phase of the exciter voltage are directly
proportional to the sum of the wall thickness within the inspection
area. Localized changes in wall thickness result in phase and
amplitude changes. These changes can be indicative of defects
such as cracks, corrosion pitting or corrosion/erosion thinning.