Structural Integrity Assessment of Welded Pressure Vessel Produced of HSLA Steel

Welded joint is a critical region of a welded structure. The operational safety of welded pressure equipment mostly depends on the behaviour of loaded weldments. Safety of welded structure is dependent on the properties of welded joint as whole and of its constituents (parent metal, heat affected zone and weld metal). In this paper the behaviour of welded joint cracked constituents is considered. Structural integrity assessment procedure is applied to welded pressure vessel produced of high-strength low-alloyed steel, operating at -40 degrees C, comparing crack driving force and material crack resistance, using path-independent contour J-integral as fracture mechanics parameter. The comparison of crack driving force, expressed by J-integral and material resistant curve, J-R curve, provide the possibility to determine the extent of the stable crack as well as the critical crack size for its final fast propagation and also to assess the structural integrity of a cracked pressure vessel