Standard Practice for In Situ Electromagnetic (Eddy-Current) Examination of Nonmagnetic Heat Exchanger Tubes
Eddy-current examination is a nondestructive method of locating discontinuities in tubing made of materials that conduct electricity. Signals can be produced by discontinuities located either on the inner or outer surfaces of the tube, or by discontinuities totally contained within the tube wall. When using an internal probe, the density of eddy currents in the tube wall decreases very rapidly as the distance from the internal surface increases; thus the amplitude of the response to outer surface discontinuities decreases correspondingly.
