Patent ID: 8888411

Claim:
A three-dimensional damping arrangement device mounted on a subsea line, whereas said three-dimensional damping arrangement device mounted on said subsea line is used to suppress dynamic motions of said subsea line by utilizing shaped surfaces designed to enhance hydrodynamic drag: whereas said shaped surfaces designed to enhance hydrodynamic drag are also referred to herein as damping shapes; said subsea line including at least one of a catenary line, or a riser line, or a catenary riser, or a rigid catenary riser, or a metal catenary riser, or a steel catenary riser, or a titanium catenary riser, or an aluminum catenary riser, or a flexible catenary riser, or an umbilical line, or a tendon line, or a cable, or a tether, or a hose, or a jumper, or a tensioned riser, or a free standing riser, or a hybrid riser tower; whereas a plurality of said three-dimensional damping arrangement devices mounted on said subsea line are mounted on said subsea line, including a single said three-dimensional damping arrangement device mounted on said subsea line; said three-dimensional damping arrangement device mounted on said subsea line incorporating said damping shapes that are mounted on said subsea line so that their combined drag per unit length of said subsea line is simultaneously enhanced by design in three mutually perpendicular directions: axial, in-plane and out-of-plane; implementations of said damping shapes having smooth edges or said damping shapes having jagged edges; said three-dimensional damping arrangement device mounted on said subsea line having implementations utilizing planar damping shapes, or said three-dimensional damping arrangement device mounted on said subsea line utilizing curved damping shapes, or said three-dimensional damping arrangement device mounted on said subsea line utilizing damping shapes incorporating curvatures and twists; whereas in particular implementations of said three-dimensional damping arrangement device mounted on said subsea line said damping shapes are oriented so that their combined drag per unit length of said subsea line is simultaneously enhanced by design in three mutually perpendicular directions: axial, in-plane and out-of-plane, whereas said dragger unit length in-plane and said drag per unit length out-of-plane are provided by helicoidal fins; whereas the helixes of said helicoidal fins form small angles with the axis of said subsea line that are defined by the design pitch values of said helicoidal fins and whereas said helicoidal fins essentially form strakes, and whereas said axial damping shapes added to said strakes are oriented so, that vectors normal to the surfaces of said axial damping shapes are essentially aligned with said axis of said subsea line at the mounting locations of said axial shapes on said subsea line; whereas said axial damping shapes are combined with said strakes, or said axial damping shapes are mounted on said subsea line independently in the vicinity of said strakes.