Document Type

Report

Publication Date

January 1979

Abstract

Performance testing of direct-tapped PVC pressure pipe was conducted at the Utah Water Research Laboratory to verify and document its capabilities under cyclic pressure conditions. Twelve samples of nominal six-inch diameter, pressure class 150 PVC pipe, manufactured to satisfy the requirements of AWWA Standard C900, were obtained from Uni-Bell Member producers. Five pipe samples were tapped and fitted with ¾ inch corporation stops under a line pressure of 80 +- 5psi. Another five samples were tapped fitted with one inch corporation stops under a pressure of 150 psi. Only corporation stops complying with AWWA Standard C800 were used. The remaining two pipe samples were not tapped, for use as controls. All twelve pipe samples were subjected to 1.5 million pressure cycles ranging from 100 to 200 psi. A continuous record of the pressure cycles was kept and a red dye was added to the water in the test pipes so that even the smallest amount of leakage could easily be detected. These cyclic tests represent an extreme condition that pressure class 150 psi, C900 PVC pressure pipe, would rarely be subjected to in service. To reach 1.5 million pressure surges, the pipe would need to be in service 171 years if such surges occurred once every hour on the average. A nearly instantaneous 5.7 fps flow velocity change would be needed to increment the internal pressure by 100 psi. This velocity change would occur, for example, if a flow rate of 525 gpm were stopped by complete closure of a valve in a nominal six-inch diameter PVC pipe line. No leakage or seepage developed around any of the threaded corporation stops during the testing through 1.5 million cycles of pressures varying from 100 to 200 psi at two second intervals.

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