Integrity assessment of corroded pipelines using dynamic segmentation and clustering

Abstract

Corrosion defects impact the resistance of hydrocarbon pipelines by increasing the risk of failure and the resulting Loss of Containment (LOC). Different approaches have been proposed to estimate this risk of failure based on empirical approaches (e.g., API 579-1/ASME FFS-1, ASME B318S or API1160), and other focus on probabilistic evaluations. Nevertheless, few works are dealing with spatial variability of corrosion defects and how segmentation (required for reliability evaluation) may affect intervention decisions. In this paper, information obtained from In-Line Inspections (ILI) is used to build a corrosion degradation model under a pressure-stress failure criterion, which is used in turn, to develop a dynamic segmentation strategy. This strategy aims at identifying optimal intervention times and Locations. Results show that existing reliability evaluations using static segmentations are suboptimal and may hide critical zones. This result is illustrated by a real case study in which corrosion evolution is better estimated, and the problems associated with conventional static segmentation are stressed.