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This significantly increases the SNR and improves inspection results.

The first is to compensate for the attenuation effect with a larger probe and/or using a longer averaging time. As you can see from the following figure, the galvanized steel strongly attenuates the signal that reaches the inspected component.Ī few easy fixes exist to help mitigate these problems and make pulsed eddy current a truly reliable technique on all types of weather jackets. Excessive attenuation reduces the signal-to-noise ratio (SNR) below acceptable levels, making inspection results unreliable. A layer of conductive galvanized steel between the probe and the target component attenuates the PEC signal (much more so than aluminum). Pulsed eddy currents work by emitting an electromagnetic signal through the insulation towards the component under test, and then listening to the signal that comes back. Worldwide, the most common type of weather jacket material is non-ferromagnetic aluminum, but in some regions ferromagnetic galvanized steel is dominant and it has proven to be an enormous challenge for pulsed eddy currents. Generally, inspection service companies and asset owners are called to use PEC to find CUI on carbon steel pipes over non-conductive insulation such as mineral wool, wrapped in a metal weather jacket (also referred to as cladding).