Near Field Testing(NFT)
NFT is a technology that employs two coils, one for transmission and one for reception. Typically, the receiver coil is close to the transmitter coil, taking advantage of the transmitter’s near-field zone — that is, the zone where the magnetic field from the transmitter coil induces strong eddy currents in the tube wall, both axially and radially. Remote-field testing (RFT) probes and NFT probes share the same frequency range. NFT is ideal for detecting corrosion, erosion, and pitting within carbon steel tubing. Because eddy currents do not pass through the tube wall, NFT is ideal for fin-fan tube heat exchangers. NFT is also much more sensitive to defects near structures like support plates and tube sheets.
- Fast Inspection.
- No need for an external reference coil.
- Easy to use.
- Unaffected by structures such as support plates and tubesheets.