A Repair Program to Minimize Failure Risk of Highly Distressed PCCP Circulating Water Lines

摘要

Arizona Public Service Company's Cholla Power Plant has four units with circulating water lines made of 66 in. to 72 in. diameter prestressed concrete cylinder pipe (PCCP) in Units 2, 3, and 4. PCCP in these three units has been in service for thirty-four to thirty-seven years. Inspections over the years have shown a high level of distress throughout the pipelines due to widespread corrosion of prestressing wires. A condition assessment and repair program has been developed and performed over multiple outages with the goal of minimizing the risk of failure of the pipeline and avoiding unscheduled shut down. This paper presents a unique condition assessment and repair program implemented over the past six years.