Ductile Iron Pipe Hazen-Williams Flow Coefficient Declines Over Time

Welcome to John’s Blog. Answers to frequently asked questions are periodically posted here. The objective is to share information about PVC pipe with readers as well as with utilities, design engineers and pipe installers. The blog provides the latest information on PVC pipe design, installation, and application for water and wastewater infrastructure projects.

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John Houle: Senior Technical Consultant, PVC Pipe Industry

John Houle holds a Master’s Degree in Civil Engineering from the University of Missouri and an MBA from the University of Oregon. He has more than 25 years of experience in the plastic pipe industry in applications engineering, market development, forensic analysis, technical writing, and standards development.

PVC Pipe Accommodates Dynamic Ground Movement

Posted By John Houle on Mar 12, 2019

Ground movement is one of the items utilities should consider when choosing pipe materials for their water and sewer systems. Movement can be caused by a slowly eroding hillside, intermittent freeze/thaw and wet/dry cycles, or a sudden cataclysmic earthquake. Whatever the cause, a pipeline that can accommodate movement has a much better chance of providing uninterrupted service.

A study by The European Plastic Pipes and Fittings Association titled “Behavior of Plastic Pipe Systems in Response to Dynamic Ground Movements” was published in 2017. More than one hundred independent sources from around the world were referenced. The paper discusses the types of movement that can occur and provides guidance on which pipe materials perform best in ground-movement situations. The conclusion was that flexible plastic pipe systems withstand the stresses and strains of dynamic ground movements much better than rigid non-plastic pipe materials.

Similar results were reported in the aftermath of large earthquakes: the Northridge (U.S.A.) quake of 1994 and the Christchurch (New Zealand) quakes of 2010 and 2011. In both cases, PVC pipe outperformed the other materials in use.

The bottom line is that PVC pipe is an excellent choice for pipes that are subject to ground movement.

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PVC water pipe was in widespread use in North America 20 years ago, but has now become the product of choice – it is a well-engineered product that provides exceptional service for water transmission and distribution systems.