TPi October 2012

plast ic pipes

Corrosion a problem for 75% of water utilities The Utah State University (USU) Buried Structures Laboratory has published a comprehensive study on water main break rates for the United States and Canada. The study will help prudent decision- making as it relates to repairing and replacing underground pipes.

of all water mains are over 50 years old. The study also found that 8 per cent of all installed water mains are beyond their useful life and the use of trenchless technologies will continue to increase with directional drilling as the most widely accepted technology with a higher satisfaction rating, and 74 per cent of utilities are considering it in the near future. The study contributes to the continuing efforts of the EPA’s Aging Water Infrastructure (AWI) research and the American Water Works Association (AWWA). The Water Main Break Rates In the USA and Canada: A Comprehensive Study can be found at: www.neng.usu.edu/mae/faculty/stevef/ UtahStateWaterBreakRatesHR.pdf

A major finding of the study is that PVC pipe has the lowest overall failure rate when compared to cast iron, ductile iron, concrete, steel and asbestos cement pipes. Another major finding is that corrosion is a major cause of water main breaks: 75 per cent of all utilities have corrosive soil conditions and combined with a high portion of old cast iron and ductile iron pipes, corrosion is ranked the second highest reason for water main pipe failure in the United States. When comparing older cast iron and newer ductile iron, thinner-walled ductile iron is experiencing failures more rapidly. Other findings include a new national metric of 264 people per mile of pipe connections, regardless of utility size. The average age of the failing water mains is 47 years old and 22 per cent

USU, located in Logan, Utah, is also home to the Utah Water Research Laboratory and has significantly contributed to water and wastewater research internationally for the last 50 years. The Buried Structures Laboratory is one of two locations in the United States that has a large scale testing facility for pipe materials and structures. Dr Steven Folkman, co-author of Buried Pipe Design, has completed the pipe materials study in which 188 utilities representing approximately 10 per cent of the nation’s installed water main pipe network responded. Water main break rates are calculated for all pipe materials used in the transport of water to create a measurement to judge pipe performance and durability.

Dr Steven Folkman, Utah State University – USA

steven.folkman@usu.edu www.engineering.usu.edu

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October 2012 Tube Products International