Allows designers to easily determine long-term deflection of PVC pipe given specified embedment (backfill) and pipe material properties. Users can vary inputs such as pipe size, wall thickness, soil properties, live loading conditions and depths of cover. PVC pipe has a long-term deflection limit of 7.5%.
This Canada-specific comparison of PVC and polypropylene (PP) sewer pipes is based on: (1) For PVC sewer pipe – decades of research and field experience: (2) For PP’s new sanitary-sewer pipe – brief history of usage with unknown longevity
Recent hydraulic research on new and in-service PVC pipe has confirmed that industry-recommended flow coefficients are conservative for design of pressure and non-pressure pipes.
Like other flexible pipe materials, PVC experiences ring deflection in response to external loads. Two PVC Pipe News articles review the deflection-response mechanism. The first article is "Back to Basics: Time Dependent Variables for Flexible Sewer Pipe." The article reviews the key elements that determine the long-term ring deflection that a flexible pipe will experience. It will also show that the time-dependent elements do not include creep. The second article is "A More Typical Deflection Response."
This Uni-Bell Technical Report, "UNI-TR-1, Deflection: The Pipe/Soil Mechanism," details design procedures for predicting the long-term deflection of buried PVC pipe.
See the "Urban Myths Die Hard" article for use of PVC gravity sewer applications at depths of 30 feet and more. Many sewer utilities have arbitrarily set depth limits for PVC which are not based on engineering knowledge.
This document has been developed by the Uni-Bell PVC Pipe Association for design and installation of PVC fittings where solid-wall PVC pipe is used in non-pressure applications. The guide provides information on the wide range of fittings that are available for various dimension ratios and outside diameters of PVC pipe through 60-inch. Also included is information on installation practices.
PVC Sanitary Sewer Pipe Standards are summarized on a single sheet.
ASTM standards limit ring deflection to 7.5%. The PVC Pipe News article, "Deflection: What Are the Limits?" looks at performance issues when ring deflection exceeds 7.5%.
How does ring deflection affect the hydraulic capacity of buried PVC sewer pipe? Read "The Effects of Deflection on Sewer Hydraulics, The Sequel," from PVC Pipe News.
Uni-Bell's "UNI-B-9-90, Recommended Performance Specifications for Polyvinyl Chloride (PVC) Profile Wall Gravity Sewer Pipe and Fittings Based on Controlled Inside Diameter (Nominal Pipe Sizes 4-48 inches)" covers all the structured wall options available for gravity sewer applications.
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