NFT- Near Field Testing - Tubes

Near Field Testing or commonly called as NFT is one of the electromagnetic testing method used to detect discontinuities on the internal surface of fin-fan type ferromagnetic (Carbon steel) heat exchanger tubes.

This RFT method is:
Fast, Accurate, Traceable, and Archivable a digital paper trail

Near Field Technology 2

In NFT - Near Field Testing 2 coils are used in transmit -receive mode. The transmitter coil is located close to the receiver coil to detect discontinuities within the near field zone of electromagnetic field of the transmitter coil. Magnetic field induces strong eddy currents (axially and radially) in the near zone of the transmitter coil.

NFT is perfect for fin-fan tube heat exchangers because eddy currents do not go through the wall of the tube. Unlike the RFT – Remote Field Testing, coils in NFT – Near Field Testing are close to each other and the electromagnetic field does not transmit through the tube wall.

Near Field Technology 3

NFT probes operate within the same frequency range as remote-field testing (RFT) probes. Similar to RFT – Remote Field Testing, discontinuities anywhere in the travel path cause changes in the magnitude and phase of the received signal. Using the Voltage plane graphs and the strip chart, phase delay and the amplitude of the signal is used to detect and size metal loss precisely. Using Voltage plane graphs, defects can be measured for its depth and volume. LMATS uses Eddyfi’s software Magnifi for signal analysis and reporting.

Ideal Applications:

Near Field Technology 1

  • Most ideal for fin-fan type heat exchanger tubes – Aluminum finned Carbon Steel tubes
  • NFT is excellent for detecting tube internal discontinuities.
  • NFT is ideal for detecting internal corrosion, erosion, pitting and axial cracking


  • NFT can detect discontinuities near support plates and tubesheets with high sensitivity
  • Very fast as compared to other electromagnetic test methods
  • NFT is not affected by the external support structures or tubesheets


Compared to conventional eddy current testing, NFT – Near Field Testing instruments and probes are complex and expensive and requires highly trained, skilled and experienced technicians. LMATS uses Eddyfi Ectane 2 unit for NFT test method. LMATS professionals are trained and experienced in NFT – Near Field Testing method.

See the Heat Exchanger tube testing selector to understand and make informed decision on the type of advanced NDT test method you may need to determine the integrity of your heat exchanger tubes.

see heat exchanger test selector
LMATS offers (NFT) - Electromagnetic tube testing and inspection using NFT- Near Field Testing system from our Melbourne, Sydney, Brisbane, Albury, Malaysia and India laboratories.
LMATS regularly performs NFT- Near Field Testing in VIC -Victoria, NSW - New SouthWales, QLD - Queesnland, QLD - Brisbane, SA - South Australia, TAS - Tasmania, NT -Northern Territory, WA - Western Australia and some of the countries aroung the world.

To find out more about LMATS  (NFT) Near Field Testing Advanced NDT Tracable Inspection Capabilities simply call us or contact us +61 3 9399 8145 or via the form