On the inspection of glass reinforced epoxy pipes using microwave NDT

Glass Reinforced Epoxy (GRE) pipes are rapidly replacing their steel counterparts in pipeline infrastructures owing to their inherent advantages like corrosion resistance, lightweight, and low maintenance costs. However, GRE pipes suffer from a variety of defects which occur during manufacturing or in-service. These defects can have disastrous consequences if undetected and treated. Therefore, regular inspection of GRE pipes is mandatory to ensure their structural integrity and avoid catastrophic failures. Non-destructive testing (NDT) of GRE pipes poses various challenges to inspection modalities which include thickness variation, rough or uneven surface conditions and lowdensity material defect. Microwave and millimeter wave based non-destructive evaluation has shown great potential in inspecting non-metallic material structures such as GRE pipes. In this paper, microwave imaging of a GRE pipe with embedded defects such as holes and notches is presented. In order to image these defects, various probes operating at different frequencies are employed herein. The images produced by the probes above are presented, and the effectiveness of microwave NDT for GRE inspection is demonstrated.