Assessment of Stress Concentration Factors of Dented Rigid Risers Under Fatigue Loadings

Abstract

In the development of oil and gas fields, subsea pipes are used in various applications, like pipelines and risers. During operation, risers can be subjected to accidents, such as collisions with other risers, anchors, rocks, or any heavy equipment or objects, which may lead to mechanical damages. These mechanical damages are commonly characterized as dents. The objective of this work is to study the effect of the introduction of plain dents on the fatigue life of rigid risers under fully reversed bending with the conduction of resonant bending tests. A three-dimensional finite element model was developed to estimate the stress concentration on dented risers under bending. Numerical simulations and experimental tests were carried out to evaluate the resulting stress concentration factors (SCFs). These SCFs can be used in the prediction of the remaining fatigue life of dented rigid risers.