We shall now describe a process for cracking passing through the wall of a tube and to measure the length of the penetrating crack

摘要

The procedure involves detecting the presence of a crack (2) in a steam generator pipe (1) and measuring its length by measuring the number and positions of inflexion points on a graph of characteristic values of signal amplitudes of Foucault currents generated when a coil of a motorized rotary probe passes in front of the crack is rotated in a spiral motion. The rotary probe coil is flat, or a combination of flat and punctiform, axial or circumferential coils