Protection of underwater elongate members

Abstract

An underwater cladding ( 10 ) for an elongate member such as a pipe, has a substantially cylindrical outer surface with a plurality of depressions ( 18 ) therein. The provision of depressions in an otherwise cylindrical outer surface of a cladding interrupts or reduces vortex induced vibrations and the absence of projections facilitates use with conventional pipe-laying equipment.

1 . An elongate underwater vortex shedding cladding ( 10 ) for an elongate member, comprising 
 an outer surface having a plurality of depressions ( 18 ) therein.    
     
     
         2 . An underwater cladding as claimed in  claim 1 , wherein the depressions ( 18 ) are arranged around the whole periphery or circumference of the cladding ( 10 ).  
     
     
         3 . An underwater cladding as claimed in  claim 1  or  claim 2 , comprising a plurality of depressions ( 18 ) having a generally circular periphery.  
     
     
         4 . An underwater cladding as claimed in  claim 3 , wherein the diameter of the circular depressions is from 1 cm to 30 cm.  
     
     
         5 . An underwater cladding as claimed in  claim 4 , wherein the diameter of the circular depressions is from 10 cm to 20 cm.  
     
     
         6 . An underwater cladding as claimed in any of the preceding claims, comprising a plurality of depressions having an elliptical periphery.  
     
     
         7 . An underwater cladding as claimed in  claim 6 , wherein the length of the major axis of the elliptical depressions is from 1 cm to 30 cm.  
     
     
         8 . An underwater cladding as claimed in  claim 7 , wherein the length of the major axis of the elliptical depressions is from 10 cm to 20 cm.  
     
     
         9 . An underwater cladding as claimed in any of  claims 6  to  8 , wherein the length of the minor axis of the elliptical depressions is from 0.5 cm to 20 cm.  
     
     
         10 . An underwater cladding as claimed in  claim 9 , wherein the length of the minor axis of the elliptical depression is from 5 cm to 15 cm.  
     
     
         11 . An underwater cladding as claimed in any of the preceding claims, comprising an external circular cross-section and wherein the largest diameter of a depression is from 5% to 50% of the external diameter of the cladding.  
     
     
         12 . An underwater cladding as claimed in  claim 11 , wherein the largest diameter of a depression is from 10% to 30% of the external diameter of the cladding.  
     
     
         13 . An underwater cladding as claimed in any of the preceding claims, comprising a plurality of depressions having a smooth depressed or recessed surface.  
     
     
         14 . An underwater cladding as claimed in  claim 13 , comprising a plurality of depressions which are smoothly concave or dished in cross-section.  
     
     
         15 . An underwater cladding as claimed in  claim 13 , comprising a plurality of depressions having a planar base wall.  
     
     
         16 . An underwater cladding as claimed in  claim 15 , wherein the depressions further comprise a side wall inclined to the planar base wall and extending to the periphery of the depression.  
     
     
         17 . An underwater cladding as claimed in  claim 16 , wherein the side wall extends perpendicularly to the planar base wall.  
     
     
         18 . An underwater cladding as claimed in any of the preceding claims, wherein the depressions are substantially identical.  
     
     
         19 . An underwater cladding as claimed in any of the preceding claims, wherein the depressions are randomly spaced over the surface of the cladding.  
     
     
         20 . An underwater cladding as claimed in any of  claims 1  to  18 , wherein the depressions are regularly spaced over the surface of the cladding.  
     
     
         21 . An underwater cladding as claimed in  claim 20 , wherein the depressions are arranged in a plurality of rows and/or columns.  
     
     
         22 . An underwater cladding as claimed in  claim 21 , wherein the depressions of the row or column are offset from those in an adjacent row or column.  
     
     
         23 . An underwater cladding as claimed in  claim 20 , wherein the depressions are arranged in a plurality of waves.  
     
     
         24 . An underwater cladding as claimed in  claim 23 , wherein adjacent waves of depressions are in phase with one another.  
     
     
         25 . An underwater cladding as claimed in  claim 23 , wherein adjacent waves of depressions are out of phase with one another.  
     
     
         26 . An underwater cladding as claimed in any of the preceding claims, comprising positively buoyant material.  
     
     
         27 . An underwater cladding as claimed in  claim 26 , wherein the buoyant material comprises syntactic foam.  
     
     
         28 . An underwater cladding as claimed in  claim 26  or  claim 27 , wherein the cladding comprises solely syntactic foam.  
     
     
         29 . An underwater cladding as claimed in  claim 26  or  claim 27 , further comprising macrospheres.  
     
     
         30 . An underwater cladding as claimed in any of the preceding claims, comprising a plurality of preformed sections assembled on, and secured to, the elongate member to be protected.  
     
     
         31 . An underwater cladding as claimed in  claim 30 , wherein the preformed sections comprise semi-tubular sections.  
     
     
         32 . An underwater cladding as claimed in  claim 30 , wherein the preformed sections comprise tubular sections.  
     
     
         33 . An underwater cladding as claimed in  claim 32 , wherein the tubular sections are split along their length.  
     
     
         34 . An underwater cladding as claimed in  claim 33 , wherein the split is longitudinal.  
     
     
         35 . An underwater cladding as claimed in  claim 33 , wherein the split is helical.  
     
     
         36 . An underwater cladding as claimed in any of  claims 1  to  29 , wherein the cladding is moulded directly onto the outer surface of the elongate member to be protected.  
     
     
         37 . An underwater cladding as claimed in any of the preceding claims, wherein the depressions are moulded into the cladding.  
     
     
         38 . An underwater cladding as claimed in any of  claims 1  to  36 , wherein the depressions are cut, machined or otherwise formed into the outer surface of the cladding after moulding the cladding.  
     
     
         39 . An underwater cladding as claimed in any of the preceding claims, wherein the cladding is profiled to receive objects other than the elongate member being protected.  
     
     
         40 . An underwater cladding as claimed in any of the preceding claims, wherein the outer surface is substantially cylindrical.