If you’ve never inspected your PCCP, knowing where to start can be challenging. We’re here to make implementing a PCCP management strategy easier for you by sharing insights from over two decades of pipeline assessment.
Prestressed Concrete Cylinder Pipe (PCCP) is the most inspected pipe in the world, with a proven track record of very low distress rates in most cases. Despite its reliable performance, just one bad pipe section can result in a pipeline failure. PCCP failures are often sudden and catastrophic. The explosive force of a failure and resulting flooding can damage property, bring traffic to a standstill, and even endanger human lives. Failures also disrupt critical services, and emergency repairs can easily cost a community well over US$1 million.1
With a proactive PCCP management strategy in place, utilities can avoid pipeline failures and optimize capital costs. Using this approach, utilities can safely manage their PCCP for less than 10 percent of full replacement costs, in most cases.
Why and How PCCP Fails
Prestressing wires give PCCP its strength. As wire wraps break, the structural integrity of the pipe decreases, and the likelihood of failure grows.
Prestressing wire wraps can corrode and break when the pipe’s protective mortar coating is damaged. Some wires are also susceptible to hydrogen embrittlement, which results from poor manufacturing practices and improper cathodic protection.
PCCP deterioration can be exacerbated by the environment, operating conditions, third-party damage, and other factors. Joint breaks, steel cylinder deterioration, and leaks can accelerate failure.
The Need for Proactive PCCP Management
Pure Technologies, a Xylem brand has inspected over 5,000 miles (3,100 km) of PCCP. Overall distress rates remain low at about four percent. However, distress rates are increasing on PCCP installed in the late 1950s and throughout the 1980s.2
We’ve long known that PCCP manufactured from 1972 to 1978 has the highest distress rates per American Water Works Association (AWWA) vintage due to the thinner mortar coatings and Class IV wire permitted during this period.2 AWWA has introduced various PCCP design and manufacturing standards over the years. An AWWA vintage is a pipe manufactured to meet a particular standard.
Failure isn’t exclusive to old PCCP or to pipes installed in the 1970s. Sometimes failures occur on relatively new PCCP pipelines, often due to issues during installation. Over 350 failures have been reported on PCCP in the ground for less than 20 years. Of those failures, 150 occurred on pipe less than 10 years old.2
Most PCCP in the ground today is still in good condition. However, pipelines installed in any decade can have wire damage. This reinforces the need for proactive PCCP management, no matter what the age of your PCCP.
Proactive PCCP Management
A proactive PCCP management approach typically consists of four steps.
- Understanding risk. An initial assessment is conducted to estimate the consequence of failure. An understanding of risk informs which pipes to inspect and what assessment methods to use.
- Next, inline leak detection and pipe wall inspection provide data on the pipeline’s actual condition. Utilities can use this data to make more informed decisions aimed at preventing failures and extending the life of their PCCP assets.
- Inspections may be followed by advanced engineering analysis to better understand likelihood of failure. Advanced analysis provides a clearer picture of risk that informs short- and long-term repair and replacement strategies.
- For critical pipelines, structural health monitoring further reduces risk by acting as an early warning system. Continuous monitoring data also strengthens advanced analyses and benefits long-term capital planning.
Understanding risk of failure helps utilities make the best possible short- and long-term PCCP management decisions. With actionable data, utilities can detect problems early and make precise repairs that prevent catastrophic failure, minimize costs, and limit disruption. Proactive PCCP management also helps utilities optimize capital budgets and extend the life of their PCCP assets.
1 Kalyan R. Piratla, Sreeganesh R. Yerri, Sepideh Yazdekhasti, Jinsung Cho, Dan Koo, John C. Matthews (2015) “Empirical Analysis of Water-Main Failure Consequences”
2 The Water Research Foundation (2020) “Managing Prestressed Concrete Cylinder Pipe (PCCP) to Extend Asset Life (5069)”