Buckling of clad pipes under bending and external pressure

Abstract

The present paper concerns the structural behaviour of clad pipes. This is a double wall pipe, composed by two pipes that are in contact through an appropriate manufacturing procedure; a thick-walled carbon steel "outer pipe", and a thin-walled corrosion-resistant inner pipe, referred to as "liner" pipe. To predict the bending response and the buckling curvature of the thin-walled liner, it is necessary to account for its contact with the confining thick-walled outer pipe. Because of this confinement, existing numerical solutions or analytical predictions for the bending buckling resistance of unconfined thin-walled tubes are inadequate to predict the buckling resistance of the bent liner. In the present work, the problem is solved numerically, using nonlinear finite elements to simulate the clad pipe, accounting for the interaction between the liner and the outer pipe. First, the manufacturing process of the clad pipe is simulated to determine the liner hoop prestressing. Subsequently, bending curvature is applied (with and without the presence of external pressure). Stresses and strains are monitored throughout the deformation stage with emphasis on possible detachment of the liner from the outer pipe and the formation of local buckling on the liner wall. Copyright © 2011 by ASME.