Technical Blog

The presence of air in a pressure pipeline is unavoidable, since dissolved air is present in the fluid being transported. This entrained air comes out of the fluid during certain operating conditions and gathers in pockets at high spots in the pipeline.

Last week’s blog entry described the importance of correctly installing PVC pipe spigots to the insertion line. This week we will look at what happens inside the pipe when the joint is assembled correctly.

Many pipe installers think that a PVC pipe spigot is correctly installed if its insertion line has disappeared into the pipe bell. They believe that the purpose of the line is to ensure that the spigot has been installed far enough to allow the gasket to seal properly. This is only partly correct.

As with many subjects, there is a germ of truth to the allegation: it is true that UV radiation from sunlight can affect the outermost surface of PVC pipe. However, even after prolonged exposure, there is no practical effect on the pipe’s performance characteristics.

PVC pipe has been in service in North America since the 1950s and has proven its ability to function well when exposed to the rigors of cold-temperature installation and operation. PVC is widely used in Canada, Minnesota, and the Dakotas, so cold weather is not a limiting factor for PVC pipe projects.

During 700 years of sustained growth for PVC water pipe, iron pipe’s market share has decreased dramatically. The iron industry has reacted by negative attacks and by spreading misinformation about PVC pipe. We thought it was time to provide a more-balanced view.

Your quick reference guide of applicable standards for PVC pressure, sewer and reclaimed water pipe.

A recent article by Indianapolis Mayor Gregory A. Ballard, which appeared in the U.S. Conference of Mayors Water Council Newsletter, discusses how water main breaks declined in his city through the use of green, durable and cost-effective PVC pipe, realizing significant savings for rate payers.

In his recent book, Confessions of a Greenpeace Dropout, Co-founder and former Leader of Greenpeace, Dr. Patrick Moore discusses the importance and usefulness of PVC pipe to our society as well as its environmental and safety attributes. He says: “It is far superior to concrete or steel pipes as it seldom breaks down and does not corrode. Vinyl pipe that has been buried for 50 years shows no sign of corrosion or decay. It is likely it could remain in service for 500 years or more…”

Recent introduction of PP into the sanitary sewer market should be cause for concern to wastewater utilities. Unsupported claims about performance, lack of rigorous studies and testing, questions regarding joint integrity, reduced safety factor, limited options for fittings and lateral connections, all point to the need for caution when considering PP alternatives over PVC pipe.