Changes to North American PVC Pressure Pipe Standards

In the United States, the American Water Works Association Standard AWWA C900, Polyvinyl Chloride (PVC) Pressure Pipe and Fabricated Fittings, 4 In. Through 12 In. (100 mm Through 300 mm), for Water Transmission and Distribution, is arguably the most widely used of all pipe material standards for water distribution and transmission, as well as for sewer force main applications. Approved by the AWWA Board of Directors in June 2007, the latest version of the standard, AWWA C900-07, became effective on September 1, 2007. The new edition is significantly different from all previous updates in that it departs from status quo with regard to factors of safety, built-in surge allowance, treatment of occasional surges, and the treatment of recurring (cyclic) surges. The goal of the AWWA PVC subcommittee was to harmonize the new revision with other thermoplastic pressure pipe standards from AWWA and ASTM International. Other goals were to improve the design approach in order to more accurately reflect the material's capabilities and to allow greater precision when comparing AWWA C900 to other thermoplastic pressure pipe standards. The primary effect of these changes will be felt by the design engineering community in North America. This paper discusses thermoplastic pressure pipe design, and provides specific examples that compare C900-07 to the previous edition.