Statistical Analysis of Acoustic Response of PVC Pipes for Crack Detection

The closed circuit television camera (CCTV) inspection is current industry standard for structural health monitoring and blockage detection in underground sewer pipes. For pipeline inspection, the CCTV camera is mounted on a self-propelled robotic crawler which passes through the pipe and relays video to an operator. These systems are contained in special vehicles and require a monitoring station with proprietary software to enable the operator to annotate the videos with notes. This makes these systems cost and labor-intensive. There is a need to investigate and develop a system that can be easily deployable and cost-effective. Recent developments in acoustic based pipeline inspection technologies have highlighted that acoustic signals can be effectively used to detect blockages in pipes. The present acoustic systems, however, are not capable of detecting cracks in underground sewer pipes. This paper examines the use of acoustic signals to detect cracks in polyvinyl chloride (PVC) pipes which are industry standard for use in sewer installations. Extensive lab testing was done on pipe samples with and without cracks to develop a method to distinguish the change in pipe's acoustic response based on presence of a crack. This paper presents the results of our analysis and lays out the future directions of this research.