Abstract
Pipelines exposed to high temperature, high pressure (HTHP) may be susceptible to the phenomenon of lateral buckling. In some cases, engineered buckle initiators (such as sleepers and Zero Radius Bends) are introduced to initiate planned lateral buckles in the pipeline at specific locations in order to ensure the loading in each lateral buckle remain acceptable. Although this is a reliable method of buckle initiation this requires buckle intiator fabrication and installation which is expensive. Therefore, there are benefits to reduce the number of buckle initiators required for such a project.
The number and location of lateral buckle initiators are typically determined during the design phase based on simulations from lateral buckling response models using finite element analysis. The predicted response of these models is dependent on a number of factors including the initial pipeline out-of-straightness, operational conditions and pipeline-seabed interaction (and pipe-structure friction where applicable).
This paper demonstrates the importance of modelling the pipeline-seabed interaction in the buckle initiator touchdown zone appropriately through the presentation of a case study. The case study shows that by appropriately considering the specific pipeline-seabed interaction in the touchdown zone and/or the potential changes in pipeline span length over a buckle initiator, lower pipeline axial strains is predicted. This implies that the potential of reducing the number of buckle initiator structures required to control the pipeline lateral buckle during operation can be demonstrated, thereby potentially saving project cost.
