Unmanned RFTC Inspection of Large Diameter Pipe

Condition assessment of prestressed concrete pipe (PCP) often includes an inspection using Remote Field Transformer Coupling (RFTC). The RFTC technique involves collecting data with a tool that travels through the pipeline, and then analyzing the collected data to identify broken wires within individual pipes. In the past, RFTC inspections relied on manned entry so that field technicians could move the RFTC tool through the pipeline. Pipes that were smaller than 36-inch were too small for this procedure so to facilitate the inspection of these smaller diameter pipelines, a remote controlled RFTC tool called PipeCrawler was developed. PipeCrawler also had the additional benefit where unlike manned inspections in which the entire portion to be inspected needs to be dewatered, only the entry points required dewatering so that the tool can be assembled inside the pipe. This decreased the dewatered costs and as well as decreased the safety concerns with manned entry. Although the original purpose of the unmanned tool was to facilitate inspections of smaller diameter pipe, the benefits of reduced dewatering requirements and the increased safety made it an attractive option for larger diameter pipes as well. In order to utilize PipeCrawler on larger diameters the tool needed to be modified. This paper describes this development as well as a case study where a large diameter pipeline was successfully inspected using PipeCrawler.