Tube Inspection – Remote Field Eddy Current
Tube Inspection – Remote Field Eddy Current
RFT is only applied to ferromagnetic materials including some ferritic stainless steels. It is good for detection and sizing of cracks, corrosion and mechanical damage in the tubes.
One limitation of RFT is that it not very good for detecting gradual wall loss. Also pits smaller than 6% of the tube cross sectional area cannot be detected. This is because of the low frequencies used for RFT inspection. We recommend backing up all Remote Field Testing work with IRIS inspection if shallow pits or general thinning is suspected. RFT is a relativity fast technique. For example, it is possible to test from 400-420 5-6 meter heat exchanger tubes in a 12-hour shift. This depends both on how clean the tubes are and to some extent the number of defects or indications needing evaluation.