Local Buckling of Tight Fit Liner Pipe

A promising possibility to reduce costs in pipelines that require corrosion resistant alloys (CRA) is the use of double wall pipe, consisting of a carbon steel outer pipe and a CRA liner pipe. During installation of such pipe, severe bending and normal force may occur, in particular during installation by reeling. Research has been carried out into the local buckling behaviour of 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. 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 theoretical models. The influence of the determining parameters for the different load cases is discussed. Research on TFP is ongoing.