Water Main Inspection
24" RFT tool demo in Louisville, Ky.
In September, 2009, Russell N.D.E. demonstrated the performance of the brand new 24" Remote Field Tool. The trial was sponsored by the U.S. Environmental Protection Agency and was facilitated by the Battelle Institute.
Louisville Water provided a 24-inch cast iron, cement lined water main for the demonstration, with a wall thickness of 0.75 inch (19mm). The water main was scheduled for replacement and was out of service during the demo.
Because the pipeline was out of service, the Tool was winched through the pipeline using a wire rope winch instead of flowing with water. Winches were positioned at each end of the pipeline, which was 627m in length. This allowed the Tool to be launched from one end and extracted at the other end, with the trailing winch being used to control the Tool speed at 5m/minute. The inspection time was 2 hours, followed by a data download of half an hour.
The image below shows the log produced by the 24" Tool of a single pipe segment (from Bell‐and‐Spigot to Bell‐and‐spigot). 168 such joint lengths were analysed, and a total of 367 wall loss instances reported. In the screen capture several local defects are detected and displayed. A histogram of the results show that a majority of the defects are less than or equal to 50% deep, with a much smaller group in the 60-80% range, and only a few defects 90% or deeper. More importantly the results from the See Snake tool show that the deep defects are concentrated within one section of the line, leaving more than half of the line with significant useful life.