Comparison of Technologies for Condition Assessment of Small-Diameter Ductile Iron Water Pipes

Abstract

Among the various diameter classes of ductile iron pipe (DIP) used in water distribution systems, small-diameter pipes [i.e., pipes with a diameter less than or equal to 305 mm (12 in.)] represent the largest proportion in use by length. Because small-diameter DIPs have thinner pipe walls, penetrations attributable to corrosion occur more rapidly, resulting in a higher susceptibility to corrosion-related failures compared to DIPs of larger diameters. Condition assessment (CA) technologies can provide vital information about the integrity of pipes, facilitating decision making on pipeline rehabilitation. Previous studies have demonstrated the benefits of CA technologies on medium- and large-diameter water mains that are known to have a high consequence of failure. However, there is an uncertainty about the cost-effectiveness of similar technologies on small-diameter DIPs. This study extends the discussion of condition assessment on water mains by evaluating commercially available CA technologies that are applicable specifically to small-diameter DIPs. The findings from this study could help water utilities make better informed selections of CA technologies and alleviate the skepticism regarding the value provided by these technologies.