Pipeline girth welds may be subjected to high plastic deformation, for instance, when installed by reeling or subject to ground movements during operation in offshore applications. Conventional stress-based design methodologies based on fracture mechanics may not be the optimum assessment methods depending on the installation or operational conditions. Therefore, a number of research programmes have been devoted to the development of new strain-based design (SBD) techniques with the view of reducing inherent conservatism in the stress-based assessment methodologies. SBD becomes more complicated when yield discontinuity also known as Lüders plateau is considered. Lüders plateau is manifested with localised plastic deformation that propagates gradually through the strained body. It has been found to impose detrimental effects on the bending capacity and fracture behaviour of pipelines.
This study aims at investigating the effect of Lüders plateau on fracture behaviour of pipeline girth welds containing flaws subject to tensile and bending loads and also internal pressure. Improved methods for assessing pipeline girth weld flaws incorporating these effects are expected to be developed.