Development of End-fitting for the NKT Flexible Pipe

The flexible pipes studied in this project are designed for
transportation of fluids like oil and gas under high pressure. Pipes used for transportation of fluid from seabed to sea level are called risers, while pipes placed on the seabed are called flowlines. Flowlines and risers are designed slightly differently due to the different loadings. While the risers are designed for dynamic loadings, the flowlines may appear is a static loaded construction. In addition to the static loading, the risers also undergo hydrodynamic loadings and, due to the flexibility of the pipe, the determination of the load reactions and deformations in the riser is governed by a complex non-linear hydroelastic problem. Especially, self-induced vibrations and complex resonance are considered. The reaction forces from the flexible riser are transferred to the production vessel through the end-fitting, which is designed to transfer these reactions during the expected lifetime of the pipe without occurrence of rupture or lack of sealing.
From a scientific point of view, the project contains several difficult problems: 1.Determination of the forces and deformations in a flexible riser undergoing static and dynamic loading. 2.Determination of the stresses and strains in the different layers of a flexible riser. 3.Construction of an end-fitting, which is able to carry the stresses from the different layers in a rational way. 4.Evaluation of the reliability of the end-fitting as regards both extreme loadings and fatigue