An Analytical Interaction Rule for Corrosion Flaws

Corrosion is a degradation mechanism that is very common in pipelines and frequently the corrosion flaws develop close one to another. Since a defect causes a perturbation in its neighboring stress field, it is a common procedure to treat close by flaws as a single one, a cluster whose dimensions envelop the whole group of defects, and some criterion must be employed to determine if two flaws are close enough to justify its clustering. The defect interaction rules available at present have practical or experimental foundations and, sometimes, one is substantially different from another. The objective of this article is to present an interaction rule based on analytical solutions for stress and strain around a volumetric flaw in a pressurized thin wall cylinder. The two possible straining modes are identified and how strain and stress propagates from a flaw into the undamaged region of the pipe is solved in the linear elastic domain. Based in this solution, a defect interaction rule is developed. This analytical interaction rule is compared to selected interaction rules commonly employed by the industry nowadays.