Technical Blog

The Ductile Iron Pipe Research Association (DIPRA) states that ductile iron (DI) pipe does not experience a decline in hydraulic performance over time. However, the very document that makes this statement is full of data that contradicts the claim.

AWWA standards for PVC pipe have been around since 1975. These standards are developed by committees comprised of three groups: • Product user members (water utilities) • Product manufacturer members • “General interest” members (from consulting engineers, certifying agencies, etc.)

In my three decades in the PVC pipe industry, I have noticed that many design engineers and utility personnel are surprised when they learn about the testing regimen that is followed by PVC pipe manufacturers.

The International Standards Organization (ISO) has developed a series of standards on environmental management. These standards, known collectively as the “14000 series,” were first published almost twenty years ago and have become the “go-to” standards for environmental topics.

My tech brief on PVC sewer-pipe fittings begins by comparing outside-diameter controlled dimensions (“OD-controlled”) to inside-diameter controlled dimensions (“ID-controlled”). While this discussion is somewhat dry, it provides essential background information.

There are two materials used for fittings for municipal PVC pipelines: PVC and ductile iron (DI). This tech brief examines both product types.

AWWA has recently published the sixth edition of its C900 standard for PVC pipe. This Tech Brief looks at milestones in the progression of the C900 and C905 standards, culminating in the combining of the two standards into AWWA C900-16.

Question – one question that I hear quite often about testing of installed PVC pressure pipe is: “What is the maximum test pressure I can use?” Answer – since every component of a pressure pipeline has a pressure rating, the simple reply is: Do not exceed the pressure rating of any of the pipeline components.

In July 2016 a study was published titled “A Framework to Evaluate the Life Cycle Costs and Environmental Impacts of Water Pipelines.” The study, funded by the Ductile Iron Pipe Association (DIPRA), “aims to develop a Pipe Material Life Cycle Assessment tool (PMLCA) that is capable of analyzing different pipe material scenarios and suggesting the best option to the various decision makers.”

Questions sometimes arise about which way the bell should be positioned in a PVC pipeline. Typically there are two concerns: 1. Does bell direction make a difference in pipeline hydraulics? 2. Does it make a difference during installation?