This paper presents a sequential integrated reeling and lateral buckling PIP Finite Element Analysis (FEA), using ABAQUS, which captures the full reeling history, and is then included in the operational analysis for lateral buckling. The FEA model is sufficiently long that both the reeling and lateral buckling analysis can be carried out using the same model. This is particularly complex to undertake, due to convergence issues, but these issues have been addressed. Using this reeling module, results show that the effects of reeling should be taken into account for high temperature pipelines.
The reeling installation process produces residual loading in the pipe-inpipe system, which has to be taken into account in any subsequent lateral, or upheaval buckling analysis. The effect of residual loads may have a significant effect at higher operational temperatures and, as a result, may reduce the ultimate loading capacity of the flowline. Presently, it is not uncommon for PIP designs to be considered now in water depths up to 3,050 meters (10,000 ft.) and flowline temperatures up to 177°C (350°F), and residual reeling strains should be taken into account in the design. Also, the residual loads may have an effect on the lateral buckling response if a thermal buckle management strategy is to be deployed in the design, such as using pre-lay sleepers or buoyancy, in order to alleviate high axial loads. In order to capture the strain history during installation, a detailed Finite Element Analysis (FEA) model has been developed that can replicate the reeling process, lay the pipeline down on the seabed, apply temperature and pressure, and then undertake lateral buckling. The analysis is performed using the commercial finite element program, ABAQUS. The significance of the FEA program described within this paper is that it undertakes an integrated reeling and lateral bucklinganalysis
