What does NDE need to achieve for cast iron pipe networks?

Abstract

Grey cast iron water pipe networks have been installed around the world, often 100–180 years ago. Cohorts (which can be defined by age, size, casting technology and geographical location, to specify but a few groups) degrade at different rates due to environmental and in-service issues, which can lead to a significant loss in mechanical performance. Hence, the management of these assets can be extremely problematic in terms of identifying priorities. The current paper considers the causes of such degradation, the consequences for defining accurate and up-to-date condition assessment protocols and hence the type and urgency of rehabilitation strategies. It follows that understanding the integrity/life expectancy of water networks requires non-destructive evaluation (NDE) of large-diameter cast iron trunk mains, with particular reference to the kinds of defects that are likely to be present and the issues that make assessment difficult. From this, recommendations are outlined for asset managers required to specify NDE protocols, based on an understanding of the nature of the material and conditions in the field.