Corrosion detection of internal pipeline using NDT optical inspection system

Abstract Internal pipe inspection, in many industries, is usually carried out using CCTV (Closed-Circuit TV) cameras and off-line human surveys through raw image assessment for failure identification. CCTV-based techniques have some limitations that restrict their implementation, namely: (1) the lack of visibility in the interior of the pipes and (2) the poor quality of the obtained images because of difficult lighting conditions. In this paper, we propose an intensity-based optical system for internal pipe inspection. The proposed optical system consists of a laser diode, an optical ring pattern generator and a CCD camera. The physical sensor behavior is explained using reflectance theory and experimental data. Finally, a surface map of the inside pipe wall is generated by extracting the intensity information existing in the pipe images. Defects and anomalies can be identified using this extracted image. Experiments in a realistic environment have been conducted and results are presented.