Fracture control - Offshore pipelines - Experimental studies on the effect of crack depth and asymmetric geometries on the ductile tearing resistance

Engineering critical assessment of offshore pipelines is usually very conservative if standardized single edge notch bend (SENB) specimens are used for the fracture mechanics testing. It is commonly accepted that the fracture toughness is dependent on the geometry constraint at the crack tip. The standardized SENB specimens have a high geometry constraint, and give lower bound fracture toughness for all geometries. For circumferential flaws in pipes the single edge notch tension (SENT) specimens is taken more into use, to establish more correct fracture toughness for the pipe in question. In this paper the effect of crack depth, misalignment and different wall thicknesses in SENT specimens have been studied. In addition the effect of crack depth and internal pressure in pipes have been studied with FE simulations.