Subsea pipelines carrying high temperature and high pressure hydrocarbon fluids are prone to failure due to global buckling. The design of such pipeline should essentially consider the effect of seabed profile (flat or uneven), types of soil on the mudline (sand or clay) and pipeline route layout. To check pipeline integrity a two step approach has been applied. In the first step, buckling susceptibility is estimated based on empirical formulation provided in research papers and code. In the next step, the buckle prone pipeline has been studied through a rigorous approach, where Finite Element Analysis tool is utilized to simulate the actual in-place scenario i.e. considering the pipeline as installed on the uneven sea bed and the effect of pipe soil interaction.
It is observed that the assumptions applied in empirical formulation result in over conservative design. Such designs have a cascading impact on the material requirement, offshore construction time and overall project cost. The FEA approach is effectively utilised to have an optimized boundary condition i.e. by allowing actual seabed modelling based on bathymetry data at close intervals, pipeline layout and a refined pipe soil contact modelling.
This paper focuses on the application of research work and code guideline for determination of susceptibility of high pressure high temperature submarine pipeline to lateral buckling and application of Finite Element Analysis (FEA) methods to assess the integrity of the pipeline system for the maximum operating condition. FE Approach can be effectively utilized to simulate the actual pipeline behaviour on seabed. It also provides the necessary design inputs for designing pipeline buckle mitigation solutions.