Analytical study of lateral thermal buckling for subsea pipelines with sleeper

Unburied subsea pipelines operating under high-temperature and high-pressure conditions tend to relieve their axial compressive force by forming lateral buckles. Uncontrolled lateral buckling may lead to pipeline failure. In order to control lateral buckling, a sleeper is often employed as a buckle-initiation technique. In this study, analytical solutions of lateral buckling for unburied subsea pipelines with sleeper are derived. An energy analysis is employed to investigate the stability of the buckled pipeline. The influence of sleeper height and sleeper friction on pipeline buckled configurations and typical lateral buckling behaviour is illustrated and analysed. The results are shown to be in very good agreement with experimental data in the literature. We also discuss the effect of imperfections and conduct an error analysis of one of the main assumptions of the proposed analytical method. Our results show that increasing the height of the sleeper or decreasing the friction between pipeline and sleeper can all be used to decrease the minimum critical temperature difference. However, only the sleeper height is effective in substantially reducing the maximum compressive stress