A Design Basis for the J-Tube Method of Riser Installation

Economic and technical factors have lead to the use of J-tubes for the connection of subsea pipelines to fixed offshore production platforms. This paper describes some of the technical aspects of this method of installation. The design analysis presented provides basic information for the prediction of pull-in loads and associated support loadings for practical installations. The analysis is based on the results of, and observations made during, a series of tests on small-scale pipelines and J-tubes. Using the knowledge of the geometrical arrangement of the contact points between the riser and J-tube, the pull-in loads and riser strains can be estimated using simple mechanics. Use of the analysis is demonstrated by means of an example of its application to a typical J-tube design.