A Modified Engineering Critical Assessment Approach for Offshore Pipelines

Environmentally assisted sub-critical static crack growth can occur in offshore pipelines exposed to aggressive production environments. Recent advances in fracture mechanics testing methods have shown that slow static crack growth rates can be reliably measured in sweet and sour environments under constant stress intensity factor (K) conditions. This has potential implications for the engineering critical assessment (ECA) of pipe girth welds subject to low cycle fatigue loading with long periods of operation under constant static load between cycles, e.g. lateral buckling. This paper demonstrates the influence of including static (i.e. time dependent) crack growth as well as fatigue crack growth in a modified pipeline ECA approach.