Enhancing Fracture Assessment of Pipe Girth Welds with Root Cracks

Abstract

Despite the widespread use of the failure assessment diagram, accurately evaluating girth weld joints with cracks remains a significant challenge within the pipeline industry, due to the mismatched strength between the parent metal and weld metal. To Address this issue, an innovative approach was proposed by converting the heterogeneous girth welds as an equivalent homogeneous structure and deriving an equivalent stress-strain relation, thereby enabling the construction of a failure assessment curve for girth welds. This study aims at enhancing the precision of defect assessment in girth welded joints. Firstly, a finite element model is developed to characterize the crack driving force in high-grade pipeline girth welds. Furthermore, an optimized calculation method is proposed for determining the reference stress and limit load of pipeline girth welds with root cracks by introducing a correction factor. Moreover, a predictive formula for the correction factor has been established based on finite element simulation results. Through rigorous numerical simulations and methodical calculation techniques, this study aims to provide guidance for the accurate evaluation of girth weld root cracks in pipeline engineering applications.