Technical Blog

In 1980 ASTM published its F679 standard for solid-wall PVC pipe and fittings. The standard’s title, “Polyvinyl Chloride (PVC) Large-Diameter Plastic Gravity Sewer Pipe and Fittings,” was appropriate at the time, because the product sizes ranged from 18-inch to a maximum size of 27-inch.

This tech brief focuses on the third method, axial deflection. Mathematically the idea is simple. For example, if you want to change direction by 5° and the allowable change in direction at each joint is 1°, then you need to deflect 5 joints.

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!

Find out how to objectively evaluate sustainability and environmental claims for underground infrastructure.

PVC pipe — an excellent choice for ground-movement situations

Calculator for designing PVC pipe for internal pressures.

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.

Some project specs require Ductile Iron (DI) pipe because of its supposed “strength” in resisting external loads. In the past it was true that iron pipe had plenty of pipe stiffness, but that was before the iron industry converted from thicker-walled Class pipe to thinner-walled Pressure Class pipe.

“Conservative” design is taught continually to all engineers during college and throughout their employment. I think we can all agree that this is a good idea – we don’t want engineers to cut corners and cause potential problems.

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.