The water distribution pipelines managed by the Bureau of Waterworks of the Tokyo Metropolitan Government are approximately 27,000 kilometers long, and upgrading all of the pipelines to earthquake-resistant joint pipes is expected to take many years and require great expense. Therefore, it is necessary to implement the renewal of pipelines in an effective and systematic manner from a medium-to long-term perspective. On the other hand, the legal durable years of water pipelines is 40 years, but the results of past surveys have confirmed that there had been many pipelines with durability of more than 40 years. In this study, we focused on the fact that the main cause of deterioration is pitting corrosion, and attempted to analyze the prediction of deterioration of ductile iron pipes based on the results of investigations of the pipe bodies and surrounding soil. The results of this analysis indicate that ductile iron pipes have service life of 50 to 90 years, which exceed the legal service life.

View full abstract

[in Japanese]

View full abstract