Technical Blog

Welcome to John’s Blog. Answers to frequently asked questions are periodically posted here. The objective is to share information about PVC pipe with readers as well as with utilities, design engineers and pipe installers. The blog provides the latest information on PVC pipe design, installation, and application for water and wastewater infrastructure projects.

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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.

Many Lessons Have Been Learned About DI Pipe

Posted By John Houle on Sep 20, 2017

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. Several of the study’s findings are described below.


Analysis: DIPRA’s Ten-Point System Not Reliable

Sixty incidents of ductile iron (DI) pipe corrosion were evaluated using DIPRA’s “Ten-Point Soil Test Evaluation Method.” The conclusion: the “Ten-Point” system is not a reliable method for determining soil corrosivity. 

Products: Ductile Iron Pipe’s Thinner Walls Mean Faster Corrosion 

Ductile iron corrodes at the same rate as cast iron, but DI pipe has much thinner walls. Thinner walls mean quicker corrosion penetration.

Corrosion Prevention: Methods Are Problematic

Commonly used corrosion-prevention methods do not always function as advertised:

DI’s asphaltic coating does not provide corrosion protection

PE encasement can sometimes do more harm than good

Conclusion: DI Pipe Corrosion Is A Large Problem, But May Be Much Larger Than Thought!

For my tech brief on "Lessons Learned, " click here.