How Corroded Pipelines Fail and How Are They Modeled?

Corrosion represents a reduction of the effective wall thickness designed to support the operating conditions of the pipeline. This metal loss may trigger a loss of containment of the transporting fluid, leading to further socioeconomic or environmental consequences. In this regard, the pipe inspection and their evaluation results are central to defining a condition-based maintenance policy. The information obtained from In-Line Inspections is relevant because it supports decisions about future interventions upon acceptability criteria. However, the level of conservatism may lead to economic losses. ILI inspections commonly report metal loss concerning corrosion defects, cracks, gouges, and dents. These flaws reduce pipe resistance to withstand the intended operation and surrounding loads, which makes it more prone to failure to plastic deformation, leak, or burst depending on the wall thickness consumption and the material strength. In engineering design, the distinction between failure and safe condition is typically defined in terms of a limit state function using the systems resistance and applied load. This chapter presents the main approaches for evaluating a permanent deformation and burst for intact and corroded pipelines, considering their relevance in maintenance and risk assessment decisions. This chapter evaluates the main available approaches concerning their conservatism level regarding each models assumptions.