Introduction: Global Buckling

Global Buckling ( Pipe buckles due to compressive force in a fully restrained pipeline )

There are two types of Global Buckling:

1. Lateral Buckling: pipe buckles horizontally
2. Upheaval Buckling: pipe bucles vertically

Fig 1: Lateral Buckling

Fig 2: Upheaval Buckling

Global Buckling is a load response mode due to compressive effective axial force but NOT a failure mode. Ultimate failure mode of Global buckling includes:

Fatigue.
Fracture.
Local Buckling.

In general, effective axial force, S exists in pipelines (OMAE 2005). If pipeline is fully restrained (especially for HP/HT), this will contribute to restrained effective force, S0 (compressive). As long as effective axial force needed to trigger buckle, Seff is greater than S0 , the pipe is safe from buckle globally. The level of axial force depends on soil resistance, environmental and trawling effects, cross section and out of straightness of pipe.