Pulsed Eddy Current (PEC) is an electromagnetic inspection technique that allows the measurement of wall thickness in low alloy steels without the need to remove insulation or prepare rough and dirty surfaces.

A transmitter coil produces a magnetic pulse which induces eddy currents within the component wall. The eddy currents in turn produce a second magnetic pulse which is detected by the receiving coil. The eddy current density decays as they progress deeper into the component wall, but the speed of decay is increased when they reach the far surface. The system monitors the rate of decay of the eddy current pulse within the steel wall. The average wall thickness over the area of measurement is derived from the comparison of the transient time of certain signal features with signals from known calibration pieces.

The bigger the distance between the coil and the component, — for example the thickness of the insulation, the wider the footprint of the measurement and the larger the area of corrosion that must be present prior to detection.

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