Electromagnetic Testing - Eddy Current Testing Applications Chapter 5 & 6

For testing, the instrument should be balanced on the structure to be tested at
a location away from the welded area so as to avoid possibly balancing on a
crack, then the area required to be tested should be scanned. During
scanning, the probe should be kept parallel to the most likely direction of
cracking. This will also detect cracking at right angles to this angle, but the
spot will be deflected downwards rather than upwards. If the balance point is
low on the screen, downward signals may not be distinguishable from noise.
Generally, the probe should be maintained at approximately right angles to
the test surface, but for maximum sensitivity when scanning along the toe of
welds, the probe should be tilted so that weld toe is immediately below the
probe tip.
Keywords:
During scanning, the probe should be kept parallel to the most likely direction
of cracking.
Charlie Chong/ Fion Zhang