The Remote Field Eddy Current (RFET) is a variation of Eddy Current send-receive probe technique. RFET technique allows the use of the differential- and absolute mode This technique is capable for the detection of localized defects with the differential mode and gradual defects with the absolute mode The detector coils are separated by a distance equivalent to two or three times the tube diameter. The receiving coils sense the flux lines that cross the tube wall twice Remote field has an equal sensitivity to internal and external indications while the phase shift is directly proportional to wall loss.

  • Up to 500 tubes of 6 meters length can be inspected in 12 hrs.
  • Can inspect ferromagnetic tubes up to 3.5 inches in diameter with 0.125 inches wall thickness.
  • Inspection speed (up to approx. 40 feet per minute).
  • Can detect large-area discontinuities such as steam erosion and baffle wear.
  • Amplitude changes in the signals sensed are not speed sensitive.
  • Flexible probes can be used to inspect and travel through U-bend areas..
  • Permanent records can be obtained on test results.

  • Limitation to distinguishing ID from OD defects..
  • Evaluation of small flaws such as pits can be difficult..
  • Instrumentation and test probes can be very expensive..
  • Tubes must be cleaned..
  • Inaccuracy in test results could occur if a discontinuity encountered differs in geometry from calibration discontinuities..