EC-Near Field

EC-NEAR FIELD

CAMPOPROXIMOTRATADA

This is a technique of electromagnetics method, which consists of the  “scanning” of all the length of the tube  using probes which emit a magnetic field which measures the lift-off or the fill factor  and converts it in signals based on amplitude (without analysis of phase). It is applied only to ferromagnetic materials, including tubes with external rooms. It can detect and measure pits, loss of  isolated or gradual thickness.

Due to  the penetration of  Eddy currents being limited to the internal surface of tubes, the testing by NFT is not affected by rooms in the external  side of tubes.

ADVANTAGES

– Allows the inspection of tubes partially embedded

– A little sensitive to support plates and tubesheets

– Speed in testing is superior to Iris

– Tubes external rooms do not interfere with result

DISADVANTAGE

– Sizing is not needed, variables interfere very often

– It requires high fill factor

– Exam execution and analysis require experience and ability

– Standard tubes manufacturing is required to all types of examined tubes

– It does not make the difference between internal and external discontinuities