Findings and Lessons Learned from Condition Assessment Inspections of Metallic Mains Using Inline Ultrasonic Technology

In 2021, WaterOne and Pure Technologies (Xylem) conducted an inline free-swimming ultrasonic pipe wall inspection of a 30-in. diameter ductile iron pipe (DIP) transmission main. The 30-in. main spans for 3.6 mi across three municipalities and consists of both unwrapped 1966 DIP and 1992 polywrapped DIP. After successfully validating defects throughout the pipeline, WaterOne leveraged the same technology in 2022 to perform inspections on four additional pipelines: a 1950 20-in. cast iron main, a 1992 polywrapped 20-in. DIP main, and a 24-in. DIP main with both unwrapped 1985 and polywrapped 1991 mains. This paper summarizes the operational aspects of the conducted pipe inspections. The inspection results identified pipe wall loss due to corrosion with examples of validations and air pocket and leak detection results. This paper also presents how these actionable insights inform pipeline management decisions. Lessons learned from both the utility’s and vendor’s perspectives are also shared.