Buckling resistance of an X80 steel pipeline at corrosion defect under bending moment

Abstract

This work investigated the resistance of a corroded X80 steel pipe to local buckling at a corrosion defect under bending moment. A nonlinear finite element model was developed to study buckling behavior of the pipe and determine critical bending moment. Parametric effects, including geometry of the corrosion defect (shape, depth, length and width), pipe geometry (pipe outer diameter and wall thickness) and operating pressure, were determined. Results show that pipeline buckling at the corrosion defect depends on the defect geometry. A rectangular corrosion feature results in a lower buckling resistance than a semispherical corrosion pit or a cylindrical grooved corrosion. The depth and width of the corrosion defect are primarily factors affecting the buckling resistance, while the effect of defect length is negligible. The critical bending moment to cause buckling of the pipe, i.e., the critical buckling moment, decreases as the defect depth and width increase. The buckling resistance of the corroded pipe can be improved by increasing the pipe outer diameter and wall thickness. The role of internal pressure in buckling resistance depends on whether a constraint condition is applied at both ends of the pipe. For buried pipelines without sealing ends, the critical buckling moment decreases as the internal pressure increases.