Piggable Pipeline WYE Connection - Development and Design
This paper considers the design and development of a 30-inch piggable subsea pipeline Y-connection which a major operator intends to install in a central North Sea gas pipeline. A Y- connection of this type enables two pipelines of the same diameter to be tied-in whilst maintaining full piggability. This will be the first known fully piggable Y-connection for a subsea gas pipeline and as such offers significant advantages over other tie-in methods, such as tee connections and riser platforms, both of which require some degree of intervention.
General aspects relating to the overall arrangement such as valving, piping layout requirements and protection and installation requirements are discussed although emphasis is placed on the Y-connection itself. The major stages in the design and development of the Y-connection are explained. These include design of the internal geometry to allow unhindered passage of pigs, structural analysis and material selection. A method developed for predicting minimum flow velocities required in the pipeline to achieve successful pigging is also presented.
KeywordsInternal Geometry SUBSEA Pipeline Maximum Equivalent Stress Minimum Fluid Velocity Dimensional Finite Element Analysis
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