Flexible pipe having a carcass layer

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

a carcass layer comprising adjacent interlocked annular elements, wherein each annular element comprises a body portion that extends around an inner circumference of a bore region and a channel region encapsulated by the body portion and provided within the body portion;

wherein the body portion comprises a first plate element and a further plate element, the first plate element and further plate element being disposed in a spaced apart and substantially parallel relationship at a centre region of each plate element and secured together at either side of the centre region to thereby define said channel region between the plate elements;

wherein the annular elements comprise a plurality of independent hoop elements disposed in a side-by-side coaxial relationship along the bore region, the body portion of each hoop element comprising means to interlock adjacent hoop elements together.

2. The flexible pipe body as claimed in claim 1 , wherein the channel region is hollow or is substantially filled with a material that dissolves within a predetermined period of time.

3. The flexible pipe body as claimed in claim 1 , wherein the channel region is substantially filled with an insulating material or a strengthening material.

4. The flexible pipe body as claimed in claim 1 , wherein the body portion of each hoop element is a closed ring having a circular outer surface.

5. The flexible pipe body as claimed in claim 1 , wherein the means to interlock adjacent hoop elements together comprises a male connection region and a female connection region disposed on either side of the centre region encasing said channel region, the male connection region of a first hoop element being locatable in the female connection region of an adjacent hoop element to thereby interlock adjacent hoop elements.

6. The flexible pipe body as claimed in claim 1 , wherein a cross section of each plate element has a substantially constant thickness.

7. The flexible pipe body as claimed in claim 1 , wherein a width to thickness ratio of each hoop element is more than 2:1.

8. The flexible pipe body as claimed in claim 1 , wherein the body portion of each hoop element in the carcass layer is formed from an identical material.

9. The flexible pipe body as claimed in claim 1 , wherein the body portion of a first plurality of hoop elements in the carcass layer is formed from a first material different from a material used to form a further plurality of hoop elements in the carcass layer.

10. The flexible pipe body as claimed in claim 1 , wherein a channel region of a first plurality of hoop elements is filled with a first material and a channel region of a further plurality of hoop elements is filled with a further material different from said first material.

11. A flexible pipe for transporting fluids from a sub-sea location, comprising:

the flexible pipe body as claimed in claim 1 ; and

one or more end fittings.

12. A jumper, riser or flow line comprising the flexible pipe as claimed in claim 11 .

13. The flexible pipe body as claimed in claim 1 , wherein the body portion is a substantially Z-shaped housing encasing said channel region, a nose region on each end of a first and further end of the Z-shape being turned inwardly towards an imaginary centre line running across a cross section of the body portion.

14. The flexible pipe body as claimed in claim 13 , wherein the carcass layer further comprises a plurality of connecting rings having a substantially H-shaped cross section, a respective connecting ring being located between adjacent hoop elements.

15. The flexible pipe body as claimed in claim 14 , wherein a downwardly turned nose region of a first hoop element rides within a substantially U-shaped channel defined by an upper surface of the H-shaped connecting ring and an upwardly turned nose region of an adjacent hoop element rides in a substantially inverted U-shaped channel defined by a lower surface of the H-shaped connecting ring.

16. The flexible pipe body as claimed in claim 1 , wherein the first and further plate elements are secured together at a first side of the channel region via an edge region of the further plate element and an intermediate region of the first plate element, said intermediate region extending to a hooked region of the first plate element.

17. The flexible pipe body as claimed in claim 16 , wherein the first and further plate elements are secured together at a second side of the channel region via an edge region of the first plate element and an intermediate region of the further plate element, said intermediate region of the further plate element extending to a hooked region of the further plate element.

18. The flexible pipe body as claimed in claim 17 , wherein the hooked regions of the first plate element and the further plate element are turned towards an imaginary centre line running across the cross section of the carcass tape whereby the hooked region of the first plate element of a first hoop element interlocks with the hooked region of the further plate element in an adjacent hoop element.

19. A method of manufacturing flexible pipe body, comprising the steps of:

locating independent hoop elements in a side-by-side coaxial relationship;

interlocking adjacent hoop elements by urging adjacent hoop elements together to form a carcass layer; and

via each hoop element comprises a body portion that extends around an inner circumference of a bore region of the flexible pipe body and a channel region encapsulated by the body portion and provided within the body portion;

wherein the body portion of each hoop element comprises a first plate element and a further plate element, the first plate element and further plate element being disposed in a spaced apart and substantially parallel relationship at a centre region of each plate element and secured together at either side of the centre region to thereby define said channel region between the plate elements, the body portion of each hoop element further comprising means to interlock adjacent hoop elements together.

20. The method as claimed in claim 19 , further comprising the steps of: interlocking adjacent hoop elements in which a respective channel region is substantially filled with an insulating material or a strengthening material.