Solid State Sensor System for Inspection of Prestressed Concrete Pressure Pipe

An important type of water pipe is the Prestressed Concrete Cylinder Pipe (PCCP). There are thousands of miles of PCCP installed in the US in sections with length up to 20 feet and diameter for 2 to 14 feet. The large size of the pipes, the thickness of the concrete (up to 10 inches) and the composite construction, which involved concrete, high strength prestressing steel wires and sheet steel cylinders, make inspection particularly challenging with existing technology.§Degradation in PCCP is characterized by corrosion that breaks one or more prestressing wires thus weakening the pipe until it fails and a leak is created. Leaks are among the largest sources of water loss and technology for detecting damage in the prestressing wires in PCCP would provide a majorenvironmental benefit for the nations, its water resources and water utilities. Existing sensor technology, based on decades-old eddy current test systems, lacks the sensitivity and signal to noise ratio needed to make rapid, high reliability inspections of PCCP. §RMD proposes a new, highly optimized probe for PCCP that uses a solid-state, field sensitive sensor offering high sensitivity and low noise at low frequencies combined with a novel, low noise eddy current source to greatly improve PCCP inspection. §In Phase I, RMD will develop a prototype probe for PCCP, measure the response of the probe to PCCP samples with and without defects to the prestressing wires, and compare the results with those obtained using a state-or-the-art ECT system for PCCP. A successful Phase I/II SBIR program will lead to improved PCCP inspection, less water loss and improved environmental safeguards for drinking water. Commercialization will result in a new product that will enhance the safety and reliability of water systems, and reduce lost water and downtime for water utilities.