“…Secondary EM field counteracts the cause of its formation, interacts with primary EM field and causes the formation of the electromagnetic coupling, shown in Figure 1. Any change in the electromagnetic parameters of conductive material causes a change in the flow of induced eddy currents, which affects the resulting EM field and coil impedance, which is measurable, [4,[6][7][8]. The ECT method has several requirements that must be secure to properly measure such as suitable frequency, the geometry of the material and placing of the ECT probe, offset, electromagnetic properties, preventing unwanted movement of probe and vibrations.…”