Tensile strain capacity of energy pipelines with flawed girth welds

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In the presence of girth weld flaws, pressurized pipelines exhibit a reduction in their tensile strain capacity under tensile axial and bending loads. Research conducted to understand this reduction is based on wide plate tests with prefabricated flaws. In addition, the objective of the recent research in this area has been to test the tensile strain capacity of high strength steels of grades X80 and higher. The results of this research has culminated in equations in the Canadian standards association code of practice CSA Z662.07 to predict the tensile strain capacity with a warning indicating that they are based on wide plate tests and do not include the effect of internal pressure. In addition, they only apply to modern high strength steel pipelines with high toughness. However, recent research on X80 pipelines have shown that tests conducted on wide plate tests dramatically over predict the tensile strain capacity of welded pipeline steel compared to the combined effect of internal pressure and axial tensile or bending stress.