Pipeline inspection using high resolution electrical capacitance tomography

A high-resolution ECT technique has been developed for pipeline inspection. The improved resolution is achieved through use of a priori knowledge of the pipe, applying a narrow band-pass filtering method (NBFM) and utilizing a Newton one step error reconstruction process (NOSER). The NBFM takes into account prior knowledge about the geometry of the pipe to improve the reconstruction processes through limiting the region of interest while the NOSER process allows the ill-posed reconstruction of the permittivity map of the material. Using these techniques and the improved sensor array, we are able to demonstrate reconstructed images of defects of 1.5 mm in depth on the interior of plastic piping at a resolution of better than 0.295%. The work presented here demonstrates a significant improvement on previous research in the spatial resolution for an ECT system.