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.
On its website the Plastics Pipe Institute (PPI) has a design tool called "PACE" (Pipeline Analysis and Calculation Environment), for the design of surge pressures for plastic pipes. The tool includes comparison of PE and PVC pipes. However, it is important to realize that although the word "Plastics" appears in its name, PPI does not speak for PVC. In fact, PPI has misrepresented PVC in favor of PE. PACE is an example. While the tool itself is functional, restrictions placed on the input variables force the results to be skewed in favor of PE. I tried to use PACE to verify the design example in the AWWA C900 standard for PVC pipe, but could not because PACE will not allow the use of the standard's inputs! To find out more, click here to read the Tech Brief. The Irony of It All The PVC pipe industry has procedures for determination of allowable surge pressures based on safety factors, material properties, and cyclic pressure research. This point is clarified by reviewing:
By contrast, PE has less rigorous justification for its cyclic-surge design methodology. AWWA Standard C906 for polyethylene pipe contains only design values without any technical explanations. The Bottom Line Driven by PPI's interest to develop design tools that favor PE, PPI has intentionally mandated that only highly unlikely design assumptions and inputs be used for PACE when it comes to PVC pipe. The flawed results produced for PVC pressure pipe are not consistent with its performance in the field over many decades or studies confirming PVC pipe longevity at more than 100 years.
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