The offshore industry is currently embarking upon new and challenging deepwater projects involving floating production systems using a range of steel riser configurations in vertically tensioned free-standing or catenary configurations. In service, these risers are subjected to a number of actions including dynamic wave and vortex induced loads.
For risers installed in deepwater and facing adverse environmental conditions these loads may lead to a critical situation for the structure due to over stressing, buckling, brittle fracture or fatigue.
In particular vortex induced vibrations (VIV) can be detrimental to slender tubular elements such as risers, due to the severe fatigue impact associated with the varying stresses resulting from large amplitude vibrations. To counteract such fatigue impact, VIV needs to be suppressed.
The most widely used technique to reduce VIV on cylindrical structure is a helical strake system.
BOE strakes are available in marine grade abrasion resistant polyurethane elastomer or a marine grade composite material and can be supplied to accommodate various installation methods including onshore, shipboard, stinger or diver/ROV retro fitting. They are supplied as interlocking circular half shells which are secured by a metallic strapping system.