Evaluating the Effects of Damage in Ductile Iron Pipelines Identifying the Critical Defect Size

The majority of ductile iron (DI) pipelines were installed in the United States in the mid-late 20^th century. Most of these pipes are in a sustainable working condition; however, any failure of these pipelines could be problematic due to the social, political, and environmental impacts of the failure. To facilitate better decision making for capital expenditures and to address the risk associated with these assets, the failure mechanisms of DI pipe must be understood. In addition, for planning and capital budgeting, it is important to determine the current condition of a deteriorated pipeline and its risk of failure. For the case study, the structural evaluation of damaged 60.96-cm (24-inch) DI pipes is discussed considering external corrosion of the pipe (the most common failure mode of DI pipe). This paper provides a clear and concise picture of how to determine the remaining strength of damaged DI pipelines by considering different pipe and soil interaction. The number size and severity of defects were randomly selected based on our previous field verification. This helps clients to determine which tool needs to be selected for condition assessment of their pipeline and will allow decision makers to enhance their asset management strategy based on inspection results and advanced computational modeling.