Effect of Crack Face Loading on Reference Stress for High Pressure Risers and Flowlines

A methodology is developed to account for the effect of crack face pressure on the reference stress in high pressure, thick walled, flowlines and risers. A detailed finite element analysis (FEA) is conducted over a range of crack depths (a/t) for long flaws (large crack aspect ratios (2c/a)) for a thick walled pipe (wall thickness/average radius = 0.28). The results from this analysis allows for the implementation of an accurate calculation of the reference stress, for thick walled pipes under high service pressures and temperatures, thereby, allowing an improved fracture prediction.