Design and testing of deep water sealine connector with non‐linear finite element analysis

Analyses were performed during the conceptual design stage of a 20in. threaded connector for deep water J‐pipe lay, as part of a research project developed by Tecnomare and partly funded by the EEC. The joint consists of two parts, namely a pin and a box, provided with cylindrical threads. It was essential for the joint design to be fully leak‐proof for both internal and external pressure and this requirement had to be satisfied also under the maximum bending moment allowable for the sealine. Sealing was accomplished on a cone surface by screwing the pin into the box until yield was reached. The FEM analysis was carried out primarily to check that the pin and box remain pressed to one another over the sealing surface in every design condition with adequate pressure to prevent leakage. For this purpose, the analysis was a powerful design technique, as it gave an easy understanding of the structural behaviour and provided proper stiffness by making the joint either larger or thinner wherever required. The m...