Technical Blog

The PE industry has developed a new pressure-pipe material that has been described as “high-strength.” Although the words “high-strength” sound reassuring, the reality is that pipe made from PE4710 is anything but.

Plastics have a material property that sets them apart from the traditional materials that most engineers studied in school. For traditional materials, there is no distinction between short-term loading and long-term loading – the material responds the same in either case. For plastics, however, there is a significant difference: plastics can handle much higher short-term loads than long-term.

Rumors have been circulating that AWWA standards allow gasketed pipe to leak. In fact, some websites for fused HDPE pipe include calculators that show huge “allowable” water-loss quantities based on this misperception.

Attached is a two-page material comparison sheet that addresses some important issues in sanitary sewer pipe selection. The document also serves as a quick reference for comparing PVC and PP non-pressure pipe.

In the sustainability world, many manufacturers claim that their products are “green.” Often the evidence supporting these claims is flimsy at best. The recently published Environmental Product Declaration (EPD) for PVC pipe does not fall into this category.

External loads usually govern the design of non-pressure pipes. For PVC sewer pipelines, one of the acceptance tests to ensure proper installation has occurred involves pulling a deflection mandrel through the pipe. Product standards for PVC gravity sewer pipes typically provide calculation methods and tables for sizing of these mandrels

Internal pressure causes longitudinal thrust forces in pipe systems. These forces are developed at changes in flow direction or pipe size, as well as at dead ends. To keep pipe joints from pulling apart, either joint restraint or concrete thrust blocking is required.

When it is necessary to transition between PVC and DI pipe, there are several considerations to keep in mind.

It is estimated that there are more than a million miles of installed PVC water pipe in rural communities across America – enough to go to the moon and back twice. At an average of say $25 per foot installed, that’s more than $125 billion in pipe value!

SHARE 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.