High-pressure pipe with pultruded elements and method for producing the same

Abstract

High-pressure flexible pipe, comprising an inner liner and a tape, wrapped around and bearing against the inner liner, wherein the tape comprises a polymer matrix and a plurality of pultruded elements embedded in the polymer matrix, wherein the pultruded elements each comprise a plurality of elongated filaments covered by polymer resin.

Claims

1. A high-pressure flexible pipe, comprising an inner liner; a tape, wrapped around and bearing against the inner liner, wherein the tape comprises: a polymer matrix; and a plurality of pultruded elements embedded in the polymer matrix, wherein the pultruded elements each comprise a plurality of elongated filaments covered by polymer resin, wherein the polymer matrix and polymer resin are made of different materials; and wherein the inner liner consists of a polymer and a gas barrier layer; or the inner liner is made of a polymer.

2. (canceled)

3. The high-pressure flexible pipe according to claim 1, wherein the polymer matrix is made of a thermoplastic polymer.

4. The high-pressure flexible pipe according to claim 1, wherein the tape is adapted for having hydrostatic strength of at least 150 bar.

5. The high-pressure flexible pipe according to claim 1, wherein the tape is wrapped helically around the inner liner.

6. The high-pressure flexible pipe according to claim 1, wherein the tape is welded to the inner liner.

7. (canceled)

8. The high-pressure flexible pipe according to claim 1, wherein the polymer matrix and the inner liner comprise materials which are from the same polymer class.

9. The high-pressure flexible pipe according to claim 1, comprising at least two layers of tape, oppositely wound in pairs.

10. (canceled)

11. The high-pressure flexible pipe according to claim 1, wherein the filaments are made of carbon.

12. The high-pressure flexible pipe according to claim 1, wherein a thickness of a single layer of tape is between 1% and 3% of the diameter of the pipe.

13. The high-pressure flexible pipe according to claim 1, wherein the polymer resin is a thermosetting resin.

14. The high-pressure flexible pipe according to claim 1, wherein the polymer resin comprises epoxy and/or a phenol.

15. (canceled)

16. The high-pressure flexible pipe according to claim 1, further comprising a polymer outer sheet surrounding the tape.

17. The high-pressure flexible pipe according to claim 1, wherein the polymer matrix comprises an additive to increase friction and adhesion with the pultruded elements.

18.-19. (canceled)

20. The high-pressure flexible pipe according to claim 1, wherein the inner liner is made of PE.

21. A method for producing a high-pressure flexible pipe, the method comprising the steps of: providing filaments; dipping the filaments in polymer resin; pulling the dipped filaments through a hole in a plate so as to form pultruded elements; embedding the pultruded elements in a polymer matrix so as to form tape; providing an inner liner which is tube-shaped; wrapping the tape around the inner liner, such that the tape bears against the inner liner wherein the polymer matrix and polymer resin are made of different materials; and wherein: the inner liner consists of a polymer and a gas barrier layer; or the inner liner is made of a polymer.

22. The method according to claim 21, wherein wrapping the tape around the inner liner comprises helically wrapping the tape around the inner liner.

23. The method according to claim 21, wherein wrapping the tape around the inner liner comprises welding the tape to the inner liner.

24.-25. (canceled)

26. A high-pressure flexible pipe, comprising an inner liner; a strength layer, arranged around and bearing against the inner liner, wherein the strength layer comprises: a polymer matrix; and a plurality of pultruded elements embedded in the polymer matrix layer, wherein the pultruded elements each comprise a plurality of elongated filaments covered by polymer resin; wherein the polymer matrix and polymer resin are made of different materials; and wherein the inner liner consists of a polymer and a gas barrier layer; or the inner liner is made of a polymer.

27. The high-pressure flexible pipe according to claim 26, wherein the polymer matrix layer is made of a thermoplastic polymer.

28. The high-pressure flexible pipe according to claim 26, wherein the polymer matrix and the inner liner comprise materials which are from the same polymer class.

29. The high-pressure flexible pipe according to claim 26, wherein the polymer matrix has been heated to a temperature above the melting temperature of the matrix.

30. The high-pressure flexible pipe according to claim 26, wherein the filaments are made of carbon.

31. The high-pressure flexible pipe according to claim 26, wherein the polymer resin is a thermosetting resin.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0042] Embodiments will now be described, by way of example only, with reference to the accompanying schematic drawings in which corresponding reference symbols indicate corresponding parts.

[0043] FIG. 1 shows a sectional view of a high-pressure flexible pipe;

[0044] FIG. 2 shows a sectional view of a tape.

[0045] The figures are meant for illustrative purposes only, and do not serve as restriction of the scope or the protection as laid down by the claims.

DETAILED DESCRIPTION

[0046] Further advantages, features and details of the present invention will be explained in the following description of some embodiments thereof. In the description, reference is made to the attached figures.

[0047] FIG. 1 shows a sectional view of a tubular-shaped high-pressure flexible pipe 1, where some components are shown partially to show the underlying components. The pipe 1 includes an inner liner 10, first layer of tape 20, second layer of tape 21 and outer sheet 30. A flexible pipe 1 can be used for a variety of different purposes and industries, for example, the transport of high pressure fluids. The shown part of the pipe 1 extends along a longitudinal axis a1, although it is flexible and does not need to extend along the longitudinal axis a1 for a long distance. Typically, the pipe has a diameter of between 100 and 200 millimetres, although this may be different depending on the specific application requirements.

[0048] Inner liner 10 is typically formed of polyethylene, though can be formed of other materials depending on the intended use of pipe 1. Inner liner 10 functions as a protective layer, and can protect pipe 1 at the inner side, particularly when transporting corrosive, abrasive or volatile fluids. The inner liner 10 may comprise a very thin gas barrier foil, at the inside, at the outside, and/or in between, which avoids or reduces leaking of gases from the pipe to the outside. The gas barrier foil may be made essentially of aluminium. Alternatively, it may be made of different metals or even gas-tight polymers.

[0049] Tape layers 20, 21 are helically wound tapes formed of pultruded elements 22 within a polymer matrix 25, which will be discussed more in detail in relation to FIG. 2. The tape layers 20, 21 reinforce the pipe 1 and provide hydrostatic pressure strength to the pipe 1, such that the pipe 1 can withstand pressures of at least 150 bar because of the reinforcement provided by the tape layers 20, 21. Each tape layer 20, 21 may be wound at a specific winding angle with respect to the longitudinal axis a1 of the pipe 1, for example, 40 degrees to 60 degrees, though it can be outside this range when suitable. Wrapping helically can ensure all parts of the inner liner 10 are adequately and consistently covered by the tape 20 without requiring cutting of the tape 20. The tape layers 20, 21 are wound in opposite directions to further promote adequate coverage of the inner liner 10 by the tape layers 20, 21. The opposite winding also increases the radial strength of the pipe 1. The strength of the tape layers 20, 21 allows the use of only two layers in most conditions, making the pipe 1 easier to form than other pipes which need many winding layers to provide sufficient strength. The tape layers 20, 21 may be supplied in very long stretches in order to provide a strong and well-connected reinforcement layer.

[0050] In forming pipe 1, tape layers 20, 21 are wound around inner liner 10 to bear directly against the inner liner 10, with no layers in between. In this manner the tape layers 20, 21 directly reinforce the pipe 1, while no further layers may be necessary. The tape layers 20, 21 can be welded to each other and to the inner liner 10 to ensure a strong connection between tape layers 20, 21 and with the inner liner 10. In this way, the tape layers 20, 21 directly provide additional hydrostatic pressure strength to the inner liner 10. Typically, the tape layers 20, 21 and inner liner 10 are made of materials that are weldable to each other, to promote a strong connection without the need of adhesives or bonding layers.

[0051] Outer sheet 30 is typically polyethylene, and functions as a protective barrier around tape layers 20, 21. The outer sheet 30 can protect and shield the pipe 1 against any outside damage or contamination. This increases the durability of the pipe 1. The outer sheet 30 is typically made of a material which is compatible with the tape 20, 21, such that they stick well together and cracks are avoided as much as possible.

[0052] Advantages of the pipe 1 include larger strength compared to other pipes, without risking corrosion or rust. This is caused by the pultruded elements 22 in the tape 20, 21 which do not contain any metal. Further advantage due to the strength of the tape 20, 21 is that only two layers of tape may be sufficient to ensure sufficient hydrostatic pressure strength such that the pipe walls remain relatively thin. This results in a relatively light weight pipe 1.

[0053] FIG. 2 shows a sectional view of a small part of tape 20, comprising three pultruded elements 22 embedded in a polymer matrix 25. The pultruded elements 22 comprise a plurality of filaments 23 covered in epoxy resin 24. The filaments 23 can be made of carbon, which combines a high tensile strength with a high flexibility. Alternatively, glass or aramid may be used. There may be 24000 to 100000 filaments 23 embedded in a single pultruded element 22, or even more. The pultruded elements 22 are formed by a pultrusion process which includes covering elongated filaments 23 in the epoxy resin 24 and pulling through a die or plate to give the pultruded elements 22 a constant cross-section. Using epoxy resin 24 results in a light and strong pultruded element which is easy to process. Alternatively, the polymer resin 24 may comprise a polyester or a vinylester.

[0054] The resin 24 surrounding the pultruded elements 23 may subsequently be cured to further increase the friction between the filaments 23. Increased friction allows for a higher tensile strength of the pultruded elements 22. After curing or heating, the pultruded elements 22 may have a tensile strength of, for example, double the tensile strength of a coated fibre with the same diameter.

[0055] The pultruded elements 22 are typically much harder than the polymer matrix 25. For example, the pultruded elements 22 may have a tensile modulus of at least 100 GPa while the polymer matrix 25 may have a tensile modulus of between 0.2 GPa and 5 GPa. The pultruded elements 23 may have a tensile strength of at least 2000 MPa. This allows the pultruded elements 23 to provide strength to the tape 20, but the polymer matrix 25 allows the tape 20 to remain flexible for easy wrapping around pipes 1 of all different sizes as well as transport and storage, for example on a bobbin.

[0056] The pultruded elements 22 are all generally aligned and parallel in a single row when they are embedded in the polymer matrix 25. The single row can ensure that the tape 20 maintains the desired flexibility for the application. In other embodiments, there could be multiple rows of pultruded elements 22 in the tape 20 and/or non-parallel pultruded elements 22 depending on the specific tape and pipe requirements.

[0057] The polymer matrix 25 is typically made of a thermoplastic, which allows for an easy to form the matrix for embedding the pultruded elements 22 for forming the tape 20. It needs to be thin enough to be flexible, but strong enough to hold the pultruded elements 22 together in the tape 20, and make sure the pultruded elements 22 do not break out of the tape 20. Typically the thickness of a single tape layer is between 1% and 3% of the diameter of the pipe 1, which keeps the pipe 1 light and flexible, while providing sufficient hydrostatic pressure strength.

[0058] The advantages of the tape 20 include a tensile strength of the tape 20 which is 50% to 100% larger compared to tape with non-pultruded carbon fibres. Furthermore, no metal is needed in the tape 20, which removes the risk of corrosion in the tape and overall pipe, leading to a strong pipe with a long working lifespan.

[0059] The present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. It will be apparent to the person skilled in the art that alternative and equivalent embodiments of the invention can be conceived and reduced to practice. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.