Subsea Arch
The Subsea Arch comprises of three main elements: Arch Structure, Mooring System and Seabed Anchor Base. The Arch Structure is a steel framework within which sits a composite or steel buoyancy element. Risers are laid over the Arch into gutters which prevent their MBR being violated, and are held in position in the gutter by a clamping system. The Mooring System tethers the buoyant Arch to the seabed and usually comprises lengths of chain, steel wire, man-made rope/fibres and various shackles, triplates etc. for connection at each end. The Seabed Anchor Base is a gravity base, suction assisted or piled structure used to hold the buoyant Arch in position on the seabed.
More specifically in Floating Production scenarios dynamic risers, cables and umbilicals often require to be held subsea in a geometric configuration known as a wave from vessel or platform to the riser base. For particular applications where some lateral restraint of risers is also required due to hydrodynamic conditions and seabed layout, a Subsea Arch System is required to provide buoyant upthrust to the risers.