Abstract: A device and method are disclosed for suppressing vortex induced vibration of a submerged elongate member such as a marine riser. Also disclosed is a marine riser having VTV suppression features. The VIV suppression features comprise multiple circumferential de-correlation rings at intervals along the member's length, each ring comprising multiple vortex tripping features at intervals around the member. The ring may for example take the form of a clamp (10) used to locate fairing units (108). However it may alternatively be a loose ring mounted on the member, or may comprise discrete features at intervals around the circumference of the member. By reducing correlation between shed vortices at different locations on the pipe, embodiments of the invention serve to prevent or reduce the coherent action of shed vortices which lead to VIV.

Abstract: A device and method are disclosed for suppressing vortex induced vibration of a submerged elongate member such as a marine riser. Also disclosed is a marine riser having VTV suppression features. The VIV suppression features comprise multiple circumferential de-correlation rings at intervals along the member's length, each ring comprising multiple vortex tripping features at intervals around the member. The ring may for example take the form of a clamp (10) used to locate fairing units (108). However it may alternatively be a loose ring mounted on the member, or may comprise discrete features at intervals around the circumference of the member. By reducing correlation between shed vortices at different locations on the pipe, embodiments of the invention serve to prevent or reduce the coherent action of shed vortices which lead to VIV.