Analytical Linear Elastic Analysis Of Lateral Buckling Of “Short” Pipelines

Christensen, Lars (INTEC Engineering)

OnePetro 

ABSTRACT

This paper gives a definition of a “short” pipeline and derives the analytical linear elastic equations governing the lateral buckling problem for “short” perfectly straight pipelines exposed to high temperature and pressure loading. The use of the equations is illustrated through an example.

INTRODUCTION

Prior to carrying out non-linear finite element analysis it is common industry practice first to assess the criticality of lateral buckling of pipelines subjected to high temperatures and pressures using linear elastic analytical equations. The equations commonly used are those developed by Hobbs (1984) who built on work by Martinet (1936) and Kerr (1978) for rail tracks. The equations were derived for “very long” straight pipelines with no imperfections using linear elastic material behavior. Several investigators have investigated the effects of initial imperfections (Tvergaard and Needleman, 1980 and 1981; Taylor and Gan, 1986; Spinazze, Vitali and Verley, 1999 and others). Tvergaard and Needleman (1980) studied the effects of initial imperfections and found that if imperfections exist, buckling can initiate before the axial force reaches the critical force derived analytically for straight pipelines. In the post buckled condition the behavior is similar to that expressed using the analytical expressions for straight pipelines. For submarine pipelines the localized post-buckling behavior is more important than the actual force under which the pipe buckles which justifies using the analytical expressions for straight pipelines without imperfections.

When the linear elastic analytical methods are insufficient to prove the structural integrity of the pipeline, non-linear analytical methods (Bruschi, Curti, Dumitrescu, Vitali and Leira, 1994), non-linear finite element analysis (FEA) (Bruschi, Spinazze, and Vitali, 1999; Mork, Collberg, Levold, and Bruschi, 1999; Torselleti, Luigino and Levold, 1999; Nystrom, Tornes, Bai and Damsleth, 1997; Bai, Nielsen and Damsleth, 1999 and others) or mitigation methods (Spinazze, Vitali, and Levold, 1999) have been used instead.