Robotic RFEC/TC Inspection of Transmission Mains with Reducers: Practical Aspects

Abstract

In 2005, a non-destructive testing evaluation was conducted on a 36-inch Prestressed Concreter Pipe (PCP) line for a large water utility in Illinois using the patented Remote Field Eddy Current / Transformer (RFEC/TC) Technology. RFEC/TC determines the number and location of wire breaks in individual PCP pipe. Due to the small diameter of this line, both man-operated bicycle-type tool and the remote-operated tethered system were used for the inspection. Data collected from the two systems were both of good quality and comparable to each other. The utility recognizes the value of the RFEC/TC inspection and plans to conduct more inspections in other PCP sections. When possible, the remote-operated tethered system, known as PipeCrawler, will be utilized because of safety considerations and because PipeCrawler is capable of inspecting pipes in a water-filled condition. In November 2006, the same water utility used the RFEC/TC technology to inspect approximately 4 miles of another 36-inch line. This inspection was challenging because it contained seven 36-inch by 24-inch reducers. Consequently, it was not possible to use the man-operated bicycle tool. In addition, it would not have been possible to use the PipeCrawler tool in its normal configuration, because of its fixed length mast. To overcome this challenge, a controllable and extendable mast was designed to fit on the PipeCrawler to facilitate the RFEC/TC inspection of PCP mains with reducers. In this paper, we will discuss the practical aspects of this.