UNBONDED FLEXIBLE PIPE

Abstract

The present invention relates to an unbonded flexible pipe including a bore for transport of a fluid wherein the unbonded flexible pipe includes an internal pressure structure including a fluid-tight polymer sheath and a barrier layer on the inside of the fluid-tight polymer sheath and bonded thereto, wherein the internal pressure sheath further includes a permeable protection sheath inside the fluid-tight polymer sheath and, wherein the barrier layer is located between the fluid-tight polymer sheath and the permeable protection sheath.

Claims

1-18. (canceled)

19. An unbonded flexible pipe having a longitudinal axis and a bore for transport of a fluid, said unbonded flexible pipe comprises one or more external armouring layers wound around an internal pressure structure defining the bore, said internal pressure structure comprises from the inside and out a permeable protection sheath, a barrier layer and a fluid-tight polymer sheath, wherein the barrier layer is bonded to the fluid-tight polymer sheath.

20. An unbonded flexible pipe according to claim 19, wherein the barrier layer is bonded to the inner surface of the fluid-tight polymer sheath by means of physical or chemical bonding.

21. An unbonded flexible pipe according to claim 19, wherein the bonding is a coherent bonding.

22. An unbonded flexible pipe according to claim 19, wherein the barrier layer at least covers a part of the inner surface of the impermeable protection sheath.

23. An unbonded flexible pipe according to claim 19, wherein the barrier layer is an elongate strip or tape.

24. An unbonded flexible pipe according to claim 19, wherein the barrier layer is an elongate strip or tape wound with windings to form a tubular structure.

25. An unbonded flexible pipe according to claim 19, wherein the barrier layer is an elongate strip or tape wound with windings to form a tubular structure and wherein the there is an overlap between adjacent windings.

26. An unbonded flexible pipe according to claim 19, wherein the barrier layer is an elongate strip or tape wound with windings to form a tubular structure and wherein there is a distance d between the adjacent windings.

27. An unbonded flexible pipe according to claim 19, wherein the barrier layer is selected from a metal foil, a polymer film, a ceramic film, or a combination of two or more of these.

28. An unbonded flexible pipe according to claim 19, wherein the barrier layer has a thickness which is less than 1 mm.

29. An unbonded flexible pipe according to claim 19, wherein the barrier layer is a single layer.

30. An unbonded flexible pipe according to claim 19, wherein the permeability coefficient of the barrier layer is at least 10 times lower than the permeability coefficient of the fluid-tight layer.

31. An unbonded flexible pipe according to claim 19, wherein the permeable protection sheath is porous.

32. An unbonded flexible pipe according to claim 19, wherein the permeable protection sheath comprises holes.

33. An unbonded flexible pipe according to claim 19, wherein the permeable protection sheath comprises holes and wherein the holes in the permeable protection sheath are reinforced.

34. An unbonded flexible pipe according to claim 19, wherein the permeable protection sheath in the surface facing the metal layer comprises one or more indentations.

35. An unbonded flexible pipe according to claim 19, wherein the permeable protection layer has a permeability coefficient which is at least 10 times higher than the permeability coefficient of the fluid-tight layer.

36. An unbonded flexible pipe according to claim 19, wherein the unbonded flexible pipe comprises a carcass.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0087] The invention will now be described in further details with reference to the drawings in which:

[0088] FIG. 1 shows an embodiment according to the invention;

[0089] FIG. 2 shows an alternative embodiment according to the invention;

[0090] FIG. 3 shows details of the layers according to the invention;

[0091] FIG. 4 shows further details; and

[0092] FIG. 5 shows a permeable protection sheath with holes; and

[0093] FIG. 6 shows a permeable protection sheath with indentations.

[0094] The drawings are only intended to illustrate the principles of the invention and are schematical depictions. Details of the unbonded flexible pipe which are not part of the invention have been omitted. In the drawings the same reference numbers are used for the same parts.

[0095] FIG. 1 shows an internal pressure sheath 1 with sub-layers for an unbonded flexible pipe. The internal pressure sheath 1 comprises a fluid-tight sheath 2, a barrier layer 3 and a permeable protection sheath 4. The barrier layer 3 is with the outer surface 3b bonded to the inner surface 2a of the fluid-tight polymer sheath 2. However, the inner surface 3a of the barrier layer 3 is not bonded to the outer surface 4b of the permeable protection sheath 4. The inner surface 4a of the permeable protection sheath 4 forms a bore 5, in which fluid is transported.

[0096] The outer surface 2b of the fluid-tight polymer sheath 2 will suitably be surrounded by a not shown pressure armor and/or tensile armor.

[0097] FIG. 2 shows an alternative embodiment of the layered internal pressure sheath 1. In this embodiment the internal pressure sheath 1 also comprises a fluid-tight polymer sheath 2, a barrier layer 3 and a permeable protection sheath 4.

[0098] In this embodiment the barrier layer 3 is applied as a tape 6, which has been wound to a tubular shape which fits with the inner surface 2a of the fluid-tight polymer sheath 2. The tape 6 is wound so the windings have an inclination in respect of the longitudinal direction 8 of the internal pressure sheath. The tape 6 is bonded with the outer surface 3b to the inner surface 2a of the fluid-tight polymer sheath 2. The tape 6 is wound in such a way so a gap 7 is provided between each of the windings of the tape.

[0099] FIG. 3 shows further details of the layered internal pressure sheath 1. The fluid-tight polymer sheath 2 has a barrier layer 3 bonded to the inner surface 2a. Adjacent to the inner surface 3a of the barrier layer 3 is the permeable protection sheath 4. In this embodiment the internal pressure sheath 1 is reinforced with a carcass 9 located on the inner surface 4a of the permeable protection sheath 4.

[0100] The permeable protection sheath 4 comprises holes 10 through which a fluid, such as a gas, may penetrate through the permeable protection sheath and come into contact with the barrier layer 3, which in this embodiment is in the form of a wound tape 6.

[0101] FIGS. 4A and B show a section of a permable polymer sheath 4 according to the invention. FIG. 4A shows a cross section of the permeable protection sheath 4 and FIG. 4B shows a part of the permeable protection sheath 4 seen towards the surface 4a.

[0102] In the cross section of FIG. 4A the permeable protection sheath 4 is seen with a hole 10 which passes through the permeable protection sheath 4 from the inner surface 4a to the outer surface 4b. As previously explained the inner surface 4a is facing the bore and is in contact with a carcass and the outer surface 4b is facing the barrier layer (in this figure the carcass and the barrier layer are not shown). The hole 10 is reinforced with a metal ring 11, which may be a bush.

[0103] In FIG. 4B the hole 10 is seen from the surface 4a of the permeable protection sheath 4 where the ring shaped metal bush 11 is also seen. The reinforcement 11 serves to prevent the polymer material in the permeable protection sheath 4 from flowing and blocking the hole 10.

[0104] FIG. 5 shows an embodiment of the permeable protection sheath 4. The permeable protection sheath 4 comprises a pattern of holes 10 distributed in the sheath. Each hole 10 passes through the permeable protection sheath from the inner surface 4a to the outer surface 4b.

[0105] FIG. 6 shows an embodiment in which the permeable protection sheath 4 comprises indentations 12. The indentations 12 have the effect that the fluid-tight polymer sheath 2 with the barrier layer 3 bonded thereto will form a bulge 13 which will penetrate into the indentation 12. In this way the permeable protection sheath 4 will be locked in respect of the barrier layer 3 and the fluid-tight polymer sheath 2, and axial displacement of the permeable protection sheath 4 is inhibited. The indention 12 may continue around the permeable protection sheath 4 thereby forming an annular groove in the permeable protection sheath.

[0106] In this embodiment the barrier layer 3 is applied as a tape 6 wound with overlapping sections 14.