阴APP导航

Pipelines are a safe, reliable mode of transport to deliver hydrocarbon products over long distances. A circumferential girth weld joins pipe segments together that introduces local discontinuities including differences in material strength, heat affected zone (HAZ) and residual stress. The pipeline may be subject to large deformations due to ground movement events associated with geohazards such as long-term slope movement, or subsidence, and, for arctic pipelines in regions with discontinuous permafrost, the effects of frost heave and thaw settlement. The pipeline mechanical integrity is directly related to attributes of the HAZ and weldment that may influence limit state criteria such as strain capacity to resist fracture, rupture and local buckling. In this study, the residual stress and microstructure evolution due to welding processes, for joining Carbon-Manganese steel pipeline segments, is examined using nonlinear transient finite element analysis (FEA). A parametric analysis was conducted using finite element analysis to evaluate the effects of welding residual stress, joint-to-joint misalignment associated with the girth weld, internal pressure, axial forces and diameter to wall thickness ratio on the local buckling response of the pipeline. The significance of residual stress and microstructure state, joint-to-joint misalignment and internal pressure on the local buckling response and compressive strain capacity is examined.