Assessment of corrosion under insulation and engineered temporary wraps using pulsed eddy-current techniques

Inspection of Corrosion under Insulation (CUI) and material degradation under Engineered Temporary Wraps (ETW) has proven to be a challenge to reliably detect and monitor using a number of NDT methods. Pulsed eddy-current has recently been identified as a potential NDT method for this application. Importantly, the lift-off between the sensor and the structure being inspected can accommodate the insulation or ETW layer. This work evaluates the effectiveness of current instrumentation to detect and assess the degradation under in-service conditions. Moreover, the components tested and the degradation effects are representative of those found in-service. A comprehensive inspection and recording process has been undertaken and the resultant data analysed to identify operating constraints of the method relative to typical components, representative degradation, dimensions of the degradation and standoff ranges.