Local Buckling of Tight Fit Liner Pipe

Abstract

A promising possibility to reduce costs in pipelines that require corrosion resistant alloys (CRAs) is the use of lined pipe, consisting of a carbon steel outer pipe and a CRA liner pipe. Research has been carried out into the local buckling behavior of the thin walled liner pipe. Important parameters are the wall thickness and material properties of the liner pipe, the contact force between the liner pipe and the outer wall, the coefficient of friction between the two walls, and the imperfections. Local buckling of the liner pipe due to combinations of bending and normal force is one of the failure modes to be considered in offshore installation of line pipe. The results of axial compression tests are presented: on liner pipe only (I), on liner pipe while positioned in the outer pipe (II), and on the joined liner and outer pipe (III). Thanks to the support of the outer pipe, local buckling of the liner pipe occurs at much higher stresses and strains than without that support. The measured buckling strains of the tests on liner pipe only (I) are in reasonable agreement with local buckling equations. Finite element calculation results are presented and compared with test results. The influence of the determining parameters for the different load cases is discussed.