Technical Blog

In trenchless installations, pipes are typically pushed or pulled into position. This pushing or pulling causes loads on the pipes that are not encountered during open-cut construction. As a result, the PVC pipe industry has developed four types of restrained-joint systems for trenchless projects.

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

Lessons Learned from Ductile Iron Pipe is a six-volume study of iron pipe corrosion. The study was undertaken by the American Concrete Pressure Pipe Association in conjunction with several large consulting engineering companies.

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.”

In August 2016, AWWA published the latest edition of its C900 standard. C900-16 is more complicated than most standards, primarily because it now includes the large-diameter sizes previously found in the C905 standard.

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.

The iron pipe industry likes to brag about pipe that has been in service for a long time – some for more than 100 years. However, it’s important to put this into proper context.

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.

“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.

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?