Investigation of pressurized elbows containing interacting corrosion defects

• The interaction of corrosion defects, in pressurized elbows was investigated.
• More than 5000 nonlinear 3D finite element analyses were conducted.
• An artificial neural network was developed for assessing corroded elbows.
• The depth and the distance between defects, have major effects on the interaction.
• The circumferential position affects the behavior of interacting defects.

The effect of single and interacting LTAs (Local Thinned Areas, caused by erosion or corrosion) on the plastic collapse pressure of straight pipes has been studied in many researches. But in case of elbows, only those with single LTAs have been studied yet. This research investigates the effect of interaction of the longitudinally aligned LTAs on the elbow failure pressure. The effects of different geometric parameters and material properties on the interaction of the LTAs were investigated through parametric finite element analyses and verified by well-known codes and formulas. It was found that in case of deeper, longer and more closely spaced LTAs, the amount of interaction is greater. Intrados LTAs had the most interacting behavior. The results of the parametric study provided a wide database, which was used for developing an artificial neural network, leading to an accurate solution for predicting the failure pressure of elbows with interacting LTAs.