Patent ID: 8915674
Filing Date: 2014-12-23
Classification: B63B,F16L

Abstract:
1. A method for installing an accessory comprising a first pipe end portion at a bottom thereof and a second pipe end portion at a top thereof onto a pipeline to be laid on the seabed, comprising the steps of: using a marine pipeline installation system for laying an offshore pipeline, the marine pipeline installation system comprising: launching the pipeline from the first position of the tower in which the tower is at the angle α with respect to the vertical, in a pipeline launch trajectory corresponding to the tower firing line into the sea; stopping the launch of the pipeline, and hanging off the launched pipeline in the hang off module; positioning the accessory in the tower firing line; after the positioning step, attaching the first pipe end portion at the bottom of the accessory to the launched pipeline in the hang off module and attaching the second pipe end portion at the top of the accessory directly to the at least one A&R cable; after the attaching step, suspending the accessory and the launched pipeline from the A&R system; after the suspending step, disengaging the hang off module from the launched pipeline; after the disengaging step, pivoting the pipeline launch tower to an accessory launch position in which the tower is at an angle γ with respect to the vertical, and the angle γ differs substantially from the angle α, thereby creating a pipeline launch trajectory that extends at an angle (γ-α) with the tower firing line and at a distance from the hang off module, the pipeline launch trajectory being large enough to launch the accessory and the launched pipeline with the A&R system; and after the pivoting step, lowering the accessory with the launched pipeline by the A&R system.