Bureau Veritas performs pipeline end expansion analysis with SAGE Profile

Daniel Cameiro and Adriano Castelo of Bureau Veritas explain how they use SAGE Profile 3D in their paper “Thermo-mechanical analyses of HP/HT pipelines with sliding foundation end structures”.

Non-buried subsea pipelines subjected to high internal pressures and high operational temperatures (HP/HT) might experience significant axial expansion. If this movement is restrained by an end structure, considerable loads can be imposed to the system. Sliding foundations have been used to minimize this effect, allowing free end displacement despite the equipment. However, thermo-mechanical behavior of HP/HT pipelines interacts with the end restrains in a complex manner. Axial displacements can accumulate over the operational cycles, in the phenomenon known as “pipeline walking”. If the sliding foundation design does not account for these accumulated displacements, axial loads (not considered in the pipeline design) might be imposed. As a result, the overall thermo-mechanical behavior in terms of lateral buckling and walking can change significantly.

This paper presents the results of finite element analyses performed to verify the importance of this interaction between the thermo-mechanical loads and the non-linear end restrain. The analyses were performed using highly non-linear tri-dimensional finite element models considering pipe-soil interaction with full 3D seabed bathymetry and load history maintained from pipe lay to operational cycles. The limited sliding range was imposed to the model ends. The results show that the pipeline global behavior after a few operational cycles is significantly different from the foreseen for the initial condition.

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