Fracture Assessment of the High Strength Super-Martensitic Stainless Steel Welds by SINTAP Defect Assessment Procedure

Abstract

13% Cr supermartensitic stainless steel is an adequate substitute material for the conventional carbon and duplex stainless steel pipes for mild corrosive environments in the oil and gas industries. By development of these new steel and respective welding technologies, structural integrity analysis of the welded pipes, is essential and a challenging task. Depending on the welding process, filler wire used, the deformation and failure behaviours of the welded pipes could be different. In this study, fitness for service analysis verified with Submerged Arc welded Middle Tension, M(T), plates as well as for the reeling deformation during the pipe-laying process. This was done by applying analysis Levels 0, I, II and III of a recently developed European Structural Integrity Assessment Procedure (SINTAP). The goal was first of all to verify SINTAP’s load-carrying capacity predictions for welded M(T) specimens (wide plates) by comparing them with corresponding experimental data. SINTAP was also used for estimating the maximum tolerable crack size within the base or weld regions under about 2.7% applied strain, which is the strain equal to the reeling process. The estimated load-carrying capacity of the plates were found on the safe side with acceptable conservatism for all the SINTAP analysis Levels.