On the fracture mechanics based development of cleavage fracture resistance criteria for the materials of large-size welded structures

Critical large-size structures are commonly made of low-alloyed steels due to their outstanding strength to weight ratio, suitable weldability and reparability for a reasonable price. Recent development of Russian sea shelf takes place in conditions of low climatic temperatures, ice and earthquake hazard. The increased operational parameters as loads, pressure, pipe diameters and so on combined with longer distance from coastal bases highly increase the engineering responsibility. Safe operation of large-size welded structures is a main aim of the developed procedures and criteria. Improved procedures are suggested to determine allowable flaw sizes taking into account their probable propagation under operational loads. Flaw size is inevitably related to the applicable procedure, criteria and amount of nondestructive inspection. The study highlights the principles for welded structures structural integrity assessment, peculiarities of test methods to evaluate the fracture toughness and ductile-to-brittle transition temperatures as well as examples of their practical application and offer to take part in the development of related standard documents.