Patent ID: 7341686

Claim:
A method of manufacturing a reelable double-walled rigid pipe for underwater transportation of fluids, wherein the pipe comprises an inner flow pipe, the interior of which defines a passage for transporting the fluid, an outer carrier pipe which surrounds the flow pipe, and a plurality of longitudinally spaced separating elements between the inner and outer pipes which define an annular space therebetween, the method comprising: selecting dimensions and properties of the inner pipe and the carrier pipe according to an intended fluid transportation application, and an intended pipeline location, and to have suitable mechanical properties which permit the double walled pipe to be plastically deformed for reeling on a vessel reel and then straightened while being laid offshore; assembling a double walled pipe using the selected carrier and flow pipes, and the separating elements; and forming a device within the double-walled pipe for arresting longitudinal propagation of buckling of the outer carrier pipe, by: placing at least one pair of sealing blocks axially spaced apart between the outer wall of the flow pipe and the inner wall of the carrier pipe; the sealing blocks having a first circumferentially extending face and a second radially opposite face, the faces being dimensioned to be in contact respectively with the outer and inner walls of the flow pipe and the carrier pipe, to define a sealed annular region within the annular space; spacing the sealing blocks so that the axial length of the annular region is at least equal to 0.5 times the external diameter of the carrier pipe, but occupies substantially less than the entire annular space; placing a curable compound in the annular region; curing the compound in the annular region; and winding the pipe on a reel after placing and curing the compound.