Flexible pipe body and method

1. Flexible pipe body for transporting fluids from a sub-sea location, comprising:

a layer comprising a helically wound tape, wherein the tape is preformed prior to winding, such that it is formed from at least a first sub-layer sandwiched between two further sub-layers, wherein the first sub-layer has a lower density than at least one of the two further sub-layers and wherein the first sub-layer comprises (i) a plurality of filaments of metal, composite, glass, or carbon fibre, or (ii) cloth of woven, braided or knitted fibres.

2. Flexible pipe body as claimed in claim 1 , wherein the first sub-layer has a lower density than both the two further sub-layers.

3. Flexible pipe body as claimed in claim 1 , wherein the further sub-layers are each of homogenous material.

4. Flexible pipe body as claimed in claim 1 wherein the first sub-layer comprises the plurality of filaments, which are randomly or semi-randomly orientated.

5. Flexible pipe body as claimed in claim 1 wherein the first sub-layer comprises the plurality of filaments, which are sintered or brazed or otherwise adhered to the further sub-layers.

6. Flexible pipe body as claimed in claim 1 wherein the first sub-layer comprises the plurality of filaments, which define one or more holes between the filaments and between the further sub-layers.

7. Flexible pipe body as claimed in claim 1 wherein the first sub-layer comprises the plurality of filaments, which are of stainless steel.

8. Flexible pipe body as claimed in claim 1 wherein the two further sub-layers are of stainless steel.

9. Flexible pipe body as claimed in claim 1 , wherein the first sub-layer comprises the plurality of filaments, which are of a nickel alloy.

10. Flexible pipe body as claimed in claim 1 wherein at least one of the two further sub-layers is of a nickel alloy.

11. Flexible pipe body as claimed in claim 1 wherein the first sub-layer comprises the plurality of filaments, which are of a titanium alloy.

12. Flexible pipe body as claimed in claim 1 wherein at least one of the two further sub-layers is of a titanium alloy.

13. Flexible pipe body as claimed in claim 1 wherein the tape is helically wound and the tape element has a cross-sectional profile such that adjacent windings of the tape interlock.

14. Flexible pipe body as claimed in claim 13 wherein the cross-sectional profile of the tape is configured such that interlocked adjacent windings are allowed a degree of lateral movement.

15. Flexible pipe body as claimed in claim 1 wherein the tape is helically wound such that adjacent windings of the tape do not interlock and the tape has a cross-sectional profile that has a width greater than a thickness.

16. Flexible pipe body as claimed in claim 1 wherein the tape is helically wound such that adjacent windings of the tape do not interlock and the tape has a stepped cross-sectional profile such that adjacent windings of the tape have a degree of overlap.

17. Flexible pipe body as claimed in claim 1 wherein the layer is a carcass, armour layer or outer layer.

18. A method of providing a flexible pipe body for

transporting fluids from a sub-sea location, comprising:

providing a layer comprising a helically wound tape,

preforming the tape prior to winding such that it is formed from at least a first sub-layer sandwiched between two further sub-layers, wherein the first sub-layer has a lower density than at least one of the two further sub-layers layers, and wherein the first sub-layer comprises (i) a plurality of filaments of metal, composite, glass, or carbon fibre, or (ii) cloth of woven, braided or knitted fibres.

19. A method as claimed in claim 18 further comprising the steps of winding the tape helically and interlocking adjacent windings.

20. A method as claimed in claim 18 further comprising the steps of winding the tape helically and overlapping adjacent windings.