Modeling of local buckling of corroded X80 gas pipeline under axial compression loading

Abstract

This work investigated buckling resistance of an X80 steel pipe containing a corrosion defect under axial compressive loading by finite element analysis. A 3-dimensional numerical model was developed to determine parametric effects on buckling behavior of the corroded pipeline. These included dimension of the corrosion defect (i.e., length, depth and width), pipeline geometry (i.e., outer diameter and wall thickness), internal pressure and mechanical properties of the steel (i.e., yielding strength, tensile strength and strain hardening exponent). The critical buckling load of the corroded pipeline is primarily affected by the depth and width of the corrosion defect, while the defect length is the least important. As the defect depth and width increase, the critical buckling load decreases, but the effect of corrosion width is not apparent when the dimensionless corrosion width wπD(w is width of corrosion defect and D is the pipe outer diameter) is greater than 0.5. The threshold defect length affecting the critical axial load of the pipeline is LDt=4.86(t is pipe wall thickness). When LDt>4.86, the influence of the defect length is ignorable. Pipeline containing a long corrosion defect feature of double buckling wave peaks, and a short corrosion defect contains a single buckling wave peak. The critical buckling load of the corroded pipeline subjected to the axial compression load increases with increased pipe outer diameter and wall thickness, but decreases with internal pressure. The increased yield and tensile strengths of the steel can improve the capacity to prevent local buckling of the corroded pipeline. The strain hardening exponent has a limited effect on the critical buckling load, which shows a significant decrease when the operating pressure is up to the critical internal pressure, resulting in yielding of the pipeline.