Increasing the Life of Your Ductile Iron Pipe with “Hot Spot” Protection

The Ductile Iron Pipe Research Association (DIPRA) has nearly 100 years of data for cast iron pipe (CI) and ductile iron pipe (DI). Thousands of DI specimens have been buried in varying corrosive soils at DIPRA test sites across the US, with testing occurring for decades. From this research, the Design Decision Model (DDM), a risk-based model for new pipe installations that scores consequence and likelihood factors, identifies criticality "zones" and provides recommendations for DI was developed. Prior to the DDM, a 10-point system was used to determine if corrosion protection was recommended. Based on this research, and working with utility owners and consulting engineers for 110 years, it is known that DI has been installed in aggressive environments without the recommended supplemental corrosion control measures. Unfortunately, this means that the pipe can require repairs or replacement prior to its minimum average service life of 100 years. What can utility owners do to address these concerns once the pipe has been installed, and these issues occur in their system? This paper will discuss a cost-effective remedial option for existing CI or DI, known as "hot spot" protection, provide options for installation methods, and discuss their advantages and disadvantages.