Saint John Proactively Manages a Critical Raw Water Main Using Advanced Robotics Inspection Tech

In the spring of 2017, one of the City’s industrial customers scheduled a maintenance shutdown limited to four days.

During the shutdown, the City’s priority was to gather visual and actionable information on the current condition of the Industrial Water Main that services the plant, last inspected five years previously. The short four-day time frame and configuration of the pipeline made it difficult to dewater, and for safety reasons, precluded a conventional manned visual inspection.

Beginning in April of 2017, and under the inspection of CBCL Limited, the City’s consulting engineer for this project, the City engaged Xylem to perform an electromagnetic condition assessment and visual inspection on 8.2 kilometers of the line.

This was the second condition assessment that Xylem has performed on the main (the first was conducted in 2012), which is constructed of prestressed concrete cylinder pipe (PCCP), wrapped with high strength steel pre-stressing wires that provide support to the structural integrity of the pipe. An electromagnetic inspection identifies and locates broken wire wraps, an early indicator of pipe deterioration. Broken wire wraps can be caused by physical damage to the pipe, corrosion, or hydrogen-induced cracking. The visual inspection identifies other signs of deterioration such as corrosion staining, mortar deterioration, and joint deficiencies.

The condition assessment was performed using Xylem’s tethered PureRobotics™ platform, equipped with electromagnetic technology and a high-definition CCTV camera that delivers and records a live video stream from inside the pipe. In this case, the robotic platform was selected because of the profile of the line and the difficulty of fully draining, which precluded a manned or free-swimming tool approach.