Numerical Analysis of Deteriorated Sub-sea Pipelines under Environmental Loads

The significant point is the bidirectional interaction technique in FSI analysis while investigating subsea corrosion effect. By this way, pipe environment is accurately modelled and fluid effects are also considered. The effect of external corrosion defects on structural behaviour of a pipeline is studied by creating a nonlinear numerical model based on the finite element method according to ABAQUS analysis program. Corrosion losses of sections are obtained from experimental results and applied to the model. Numerical model is formed by a span of sub-sea pipeline that is subjected to environmental loads. Seismic and wind-generated irregular wave loads are considered as environmental loads. Irregular wave is represented with equivalent eight regular waves via FFT. The pipe is modelled according to two different types which are non-corroded(intact) and corroded (deteriorated) to demonstrate corrosion effects on it. The visible type of corrosion in marine environment is named 'pitting' corrosion, in which the material loss is locally interpenetrated over the surface. By considering this situation, the corroded and non-corroded pipes are modelled as 3D solid elements. The main point is revealing how the subsea corrosion affects the structural behaviour of pipelines on the basis of implementation of experimental results to a model structure due to changes of stresses and displacement.