Technical Blog

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John Houle: Senior Technical Consultant, PVC Pipe Industry

John Houle holds a Master’s Degree in Civil Engineering from the University of Missouri and an MBA from the University of Oregon. He has more than 25 years of experience in the plastic pipe industry in applications engineering, market development, forensic analysis, technical writing, and standards development.

Time to Redefine “Large Diameter” PVC Pressure Pipe

Posted By John Houle on Oct 1, 2014

In 1975 AWWA published the C900 standard for PVC pressure pipe and fittings. The standard’s product sizes ranged from 4-inch through 12-inch. In 1988 a second PVC pressure pipe standard was published – this standard, AWWA C905, included sizes from 14- through 24-inch.

The two standards differed markedly in their product design: C900 used a safety factor of 2.5, while C905 employed an SF of 2.0. Because of this distinctly different design approach, there was an obvious break between small diameter pipe (4- through 12-inch) and large-diameter pipe (14- through 24-inch.)

In the 35+ years since C905 was published, however, three major changes have occurred that make the transition point to large diameter less clear:

The design methods in the two standards have been harmonized.
In 2016, AWWA C900 and C905 were merged into a single standard: AWWA C900.
The largest size being produced has more than doubled to 60 inches.

What was considered “large-diameter” in 1988 is now relatively small. Unfortunately, some specifiers still consider 14-inch as a large pressure pipe – with 60-inch as the comparison, I think it is time to revisit the definition of “large-diameter.”

Click here for my Tech Brief on this subject.

PVC’s market share for potable water mains and sewer forcemains in North America has been growing steadily for more than 70 years. The large market share gained by smaller-diameter PVC pipe is a result of the product’s outstanding performance characteristics – the same advantages that are provided by larger-diameter products.