An Optical Method for Inspecting Surface Defects inside a Gas Pipe

An innovative inspection method to assess the condition of pipelines is proposed in this paper. The standard pipe inspection technique، based on closed-circuit television systems، has a relatively poor performance. A video camera is mounted on a robot and the video recording is provided off-line to an engineer who classifies any defects. Two of the main disadvantages of such camera-based inspection systems are 1) the poor quality of the acquired images due to difficult lighting conditions and 2) the susceptibility to error during the off-line video assessment conducted by human operators. The focus of this research is the automated identification and location of discontinuities in the internal surface of pipes. The sensor used is an assembly of a CCD camera and laser diode to generate a ring-shaped laser pattern. The automatic recognition and localization of pipe defects are carried out by means of the computation of a partial histogram based on image processing techniques. The proposed method has been conducted on a real gas pipe and the results are presented.