Several studies have been performed in order to better understand the local buckling of pipes subjected to internal pressure, axial load and bending moment. Experimental tests have been carried out and simplified analytical solutions have been developed in order to predict the pipe bending moment capacity and the allowable level of deformation. In recent years, the comparison of experimental tests and Finite Element Analysis (FEA) results, obtained with standard finite element structural codes available on the market such as ABAQUS, ADINA, ANSYS, etc., has demonstrated the capability of FEA to give robust and reliable results. This paper describes the main findings of the study performed in the HOTPIPE project aiming at establishing the failure mechanisms and limit state formulations of pipes subjected to internal pressure, bending moment and axial compression.
Recent development plans envisage the transport of hydrocarbons at temperature and pressure conditions far more severe than in past projects. Indeed, technical feasibility of certain inter-field lines has been questioned as a consequence of direct application of design guidelines currently in force. This fact gave rise to a critical review of design criteria developed in the early seventies. Euler-bar buckling may be a potential hazard for in-service pipelines/flowlines at high pressure-high temperature conditions. The Euler-bar buckling is induced by the frictional restraint of thermal expansion due to the change in temperature or internal pressure and may occur for both buried and unburied pipelines. Lines placed above ground or buried in relatively shallow trenches present two different modes of buckling: lateral/snaking and vertical/upheaval. In the late seventies and early eighties, a few experimental tests were carried out to investigate the buckling mechanisms of pipes subject to internal pressure, axial force and bending moment, see e.g. Bouwkamp and Stephen (1973), Sherman (1976) and Gresnigt (1986).
