Fatigue Crack Growth in Steel used in Oil and Gas Pipelines

Oil and gas pipelines are subject to cyclic loads and can develop fatigue cracks. Particularly, pipes with longitudinal fatigue cracks are of utmost importance since they are associated with bursting. With this issue in mind a method to predict fatigue crack growth was sought out. Hence, the objective of the current study was to develop a model to conservatively estimate fatigue life of a full-scale pipe specimen with a longitudinal fatigue crack. Fracture mechanics concepts in conjunction with a statistical model and both experimental and numerical techniques were used to construct this model. Nine compact tension specimens, one full-scale pipe specimen with longitudinal crack and a finite element model were used in this study. The fatigue life predicted by the model was compared to the fatigue life of a full-scale pipe specimen and reasonable results were found