Inventors: Stephen Owen Mast

[0001] This application claims the benefit of, and priority through, United States Provisional

Application 62/065,347, titled "Composite Wrapped Steel Tubes for Use in Umbilicals," filed October 14, 2014.

BACKGROUND

[0002] Carbon fiber composites have been used in the pressure vessel industry and have started to be used subsea for subsea pipe and repair. Such uses, however, have been limited to pipe usage rather than tubes for umbilicals.

[0003] There is a need for higher pressures to service the higher pressure reservoirs, and subsea equipment is now demanding hydraulic and chemical injection lines up to 20 psi. Steel tubes to this pressure require the use of more expensive steel, especially as current super duplex steels cannot be manufactured thick enough to meet customer demands. The alternatives have led to the proposed use of Hyper Duplex (SAF 3207), but this is even limited to use less than 1 inch in diameter. Moreover, the wall thicknesses required can make the umbilicals heavy, stiff and expensive to produce.

FIGURES

[0004] Various figures are included herein which illustrate aspects of embodiments of the disclosed inventions.

[0005] Fig. 1 is a cutaway view in partial perspective of an illustrative embodiment of a composite wrapped steel tube disposed in an umbilical;

[0006] Fig. 2 is a cutaway view in partial perspective of an illustrative embodiment of a composite wrapped steel tube; and

[0007] Fig. 3 is a block diagram of an exemplary system for producing a composite wrapped steel tube. DESCRIPTION OF EXEMPLARY EMBODIMENTS

[0008] Referring to Fig. 1, in an embodiment umbilical cable 100 comprises outer umbilical sheath 2, one or more conduits 1 disposed within outer umbilical sheath 2; one or more conductors 3 disposed within a first predetermined set of conduits 1; and one or more fillers 4 disposed proximate a predetermined set of conduits 1 within outer umbilical sheath 2. One or more of the conduits 1 may be a signal conduit.

[0009] Referring additionally to Fig. 2, each conduit 1 typically comprises metallic inner wall 40 and carbon fiber composite outer wall 30 disposed substantially continuously about outer surface 5 of metallic inner wall 40. As carbon fiber is significantly stronger than steel, it can typically help reduce the outer diameter dimension of and the amount of material used for conduit 1.

[0010] Metallic inner wall 40 may comprise a super duplex material, a lean duplex material, a hyper duplex material, or the like, or a combination thereof. In certain embodiments, metallic inner wall 40 comprises steel, by way of example and not limitation such as stainless steel, and, typically, comprises both steel and carbon fiber composite. As a driving design feature for pressure of steel tubes is in the hoop direction, using steel to take up the tensile allows conductors such as fiber can be laid at high lay angles to provide the required hoop strength.

[0011] Referring back to Fig. 1, conductors 3 may comprise an electrical conductor, which may be a low voltage electrical conductor or a medium voltage electrical conductor; a fiber optic conductor; or the like; or a combination thereof.

[0012] Conduit 1 may further comprise one or more welded, reinforced interfaces 11 ,12 disposed about one or more ends 6,7 of conduit 1. Typically, interfaces 11,12 are welded and then reinforced by any convenient means, allowing such welds to be inspected and/or X-rayed.

[0013] In the operation of exemplary embodiments, referring now to Fig. 3, umbilical cable 100 may be manufactured by providing a predetermined length of conduit 1 , which, as descried above comprises a metal, from source 201 to coating station 200 where outer surface 5 of conduit 1 is coated with a carbon fiber in or at coating station 200 to create a substantially continuous composite outer wall disposed about outer surface 5 of conduit 1 and, thereby, create a coated conduit, referred to herein as coated conduit la. Coated conduit la may be taken up from coating station 200 such as at bobbin 202 after which it may be disposed within outer umbilical sheath 2 of umbilical 100. By way of example and not limitation, a plurality of coated conduits la may be disposed within one or more such outer umbilical sheaths 2.

[0014] At any convenient time, one or more conductors 3 (Fig. 2) may be disposed within conduit 1.

Additionally, at any convenient time, one or more fillers 4 may be disposed within the outer umbilical sheath proximate one or more coated conduits 1 a.

[0015] Takeup bobbin 202 may be inserted in a cabler and umbilical 100 then built as is common practice for such construction.

[0016] The foregoing disclosure and description of the inventions are illustrative and explanatory.

Various changes in the size, shape, and materials, as well as in the details of the illustrative construction and/or an illustrative method may be made without departing from the spirit of the invention.