Investigation on the strain capacity of girth welds of X80 seamless pipes with defects

An experimental and numerical study has been carried out on the strain capacity of girth-welded X80 pipes subject to displacement-controlled conditions. The focus of this research is fracture limit state. This paper contains details of small-scale and full-scale experiments on X80 line pipe specimen containing girth welds and different initial defect dimensions in order to understand their fracture behaviour. The effect of internal pressure on strain capacity is also investigated through full-scale bending tests. Extensive accompanying Finite Element Analysis has been carried out with a focus on weld overmatch combined with Heat Affected Zone. The analysis results are compared with experimental results and the current Engineering Critical Assessment procedures.