Fracture Analysis Of Butt Joint Girth Welds Of Pipelines With Different Wall Thickness

Pipeline transportation has become the main way of transporting oil and natural gas in various countries in the world,and long-distance pipelines are made of a large number of steel pipes or pipe fittings connected by girth welds,so girth welds are an indispensable part of long-distance pipelines.However,due to the limitation of welding technology and the influence of the on-site construction environment,some defects such as cracks,pores,slag inclusions,under-welding,etc.inevitably appear in the girth welds,which are particularly serious when welding girth welds of pipes with different wall thicknesses.In this paper,the main research object of the butt-weld girth welds of unequal-wall pipes is to establish a plane axisymmetric finite element model of the internal staggered edge,the internal staggered edge and the external staggered edge after the transition process of the trimming edge.The internal pressure,axial tension and axial displacement were used to analyze the stress and strain of the girth welds of pipelines with different wall thicknesses.The stress concentration factor and strain concentration factor of the girth welds were calculated to study the internal pressure load,pipeline The influence of wall thickness difference,strength matching coefficient,and the angle of edge-cutting transition on the stress concentration and strain concentration degree of butt-welded girth welds of pipes of unequal-wall thickness provides for the design and safety evaluation of butt-welded girth welds of pipes of unequal-wall thickness guide.