Thermoplastic composite

Abstract

A method of making a flexible pipe layer, which method comprises: commingling polymer filaments and carbon fibre filaments to form an intimate mixture, forming yarns of the commingled filaments, forming the yarns into a tape, and applying the tape to a pipe body to form a flexible pipe layer.

Claims

1. A thermoplastic composite comprising fluoropolymer filaments and carbon fibre filaments, wherein the fluoropolymer filaments and carbon fibre filaments are commingled to form an intimate mixture, and wherein the fluoropolymer has a melt flow index (230° C./2.16 kg) in the range of 50 to 80 g/10 min, wherein the carbon fibre filaments have a tow size of 3000 to 12000.

2. A composite according to claim 1, wherein the fluoropolymer has a melt flow index (230° C./2.16 kg) in the range of 60 to 70 g/10 min.

3. A composite according to claim 1, wherein the fluoropolymer is selected from at least one of perfluoroalkoxy alkanes (PFA), poly(ethene-co-tetrafluoroethene) (ETFE), polytetrafluoroethylene (PTFE), fluorinated ethylene propylene (FEP) and polyvinylidene fluoride (PVDF).

4. A composite according to claim 1, wherein the fluoropolymer is polyvinylidene fluoride (PVDF).

5. A composite according to claim 1, wherein the fluoropolymer is present in an amount of 30 to 70 weight % of the total weight of the fluoropolymer and carbon fibre.

6. A composite according to claim 1, which is in the form of a yarn.

7. A composite according to claim 6, wherein the composite is a tape formed from a plurality of yarns.

8. A composite according to claim 7, wherein the tape comprises a first region formed from a plurality of yarns having a first concentration of carbon fibre, and a second region formed from a plurality of yarns having a second concentration of carbon fibre, wherein the first and second concentrations are different.

9. A composite according to claim 7, wherein the tape comprises a region formed from a plurality of yarns, and a different region formed from a plurality of yarns consisting essentially of the fluoropolymer filaments.

10. A flexible pipe comprising at least one pipe layer formed from a tape of a composite according to claim 1.

11. A pipe as claimed in claim 10, wherein the at least one pipe layer formed from a tape of the composite is a pressure armour layer, which is positioned adjacent to a tubular polymer layer.

12. A pipe according to claim 11, wherein the tubular polymer layer is formed on the inside of the pressure armour layer as a fluid barrier layer.

13. A pipe according to claim 10, wherein the pipe layer is obtainable by wrapping the tape around a pipe body to form a pipe layer, and heating the tape so that the fluoropolymer filaments melt around the carbon filaments to form a fluoropolymer matrix.

14. A method of making a thermoplastic composite according to claim 1, wherein the method comprises commingling fluoropolymer filaments and carbon fibre filaments to form an intimate mixture.

15. A method according to claim 14, wherein the filaments are commingled using a compressed gas or a series of combs to form the intimate mixture of the filaments.

16. A method according to claim 14, wherein the method comprises forming yarns of the commingled filaments, and compressing or extruding the yarns to form a tape of the thermoplastic composite.

17. A method according to claim 16, wherein the method comprises: arranging a first region of yarns having a first concentration of carbon fibre adjacent to a second region of yarns having a second concentration of carbon fibre, and compressing or extruding the yarns to form a tape, whereby the tape has a first region having a first concentration of carbon fibre, and a second region having a second concentration of carbon fibre.

18. A method according to claim 16, wherein the method comprises arranging a first region of yarns that contain carbon fibre adjacent to a second region of yarns consisting essentially of fluoropolymer, and compressing or extruding the yarns to form a tape, whereby the tape has a first region containing carbon fibre, and a second region consisting essentially of fluoropolymer.

19. A method as claimed according to claim 16, wherein the method comprises wrapping the tape around a pipe body, and heating the wrapped tape so that the fluoropolymer filaments melt around the carbon filaments to form a fluoropolymer matrix.

20. A method according to claim 19, wherein the pipe body comprises an extruded tubular polymer layer.

Description

(1) Embodiments of the invention are further described hereinafter with reference to the accompanying drawings, in which:

(2) FIG. 1 illustrates a flexible pipe body; and

(3) FIG. 2 illustrates a riser, flowline and jumper.

(4) In the drawings like reference numerals refer to like parts.

(5) Throughout this description, reference will be made to a flexible pipe. It will be understood that a flexible pipe is an assembly of a portion of pipe body and one or more end fittings in each of which a respective end of the pipe body is terminated. FIG. 1 illustrates how pipe body 100 is formed in accordance with an embodiment of the present invention from a combination of layered materials that form a pressure-containing conduit. Although a number of particular layers are illustrated in FIG. 1, it is to be understood that the present invention is broadly applicable to coaxial pipe body structures including two or more layers manufactured from a variety of possible materials. For example, the pipe body may be formed from polymer layers, metallic layers, composite layers, or a combination of different materials. It is to be further noted that the layer thicknesses are shown for illustrative purposes only.

(6) As illustrated in FIG. 1, a pipe body includes an optional innermost carcass layer 101. The carcass provides an interlocked construction that can be used as the innermost layer to prevent, totally or partially, collapse of an internal pressure sheath 102 due to pipe decompression, external pressure, and tensile armour pressure and mechanical crushing loads. The carcass layer is often a metallic layer, formed from stainless steel, for example. The carcass layer could also be formed from composite, polymer, or other material, or a combination of materials. It will be appreciated that certain embodiments of the present invention are applicable to ‘smooth bore’ operations (i.e. without a carcass layer) as well as such ‘rough bore’ applications (with a carcass layer).

(7) The internal pressure sheath 102 acts as a fluid retaining layer and comprises a polymer layer that ensures internal fluid integrity. It is to be understood that this layer may itself comprise a number of sub-layers. It will be appreciated that when the optional carcass layer is utilised the internal pressure sheath is often referred to by those skilled in the art as a barrier layer. In operation without such a carcass (so-called smooth bore operation) the internal pressure sheath may be referred to as a liner.

(8) A pressure armour layer 103 is a structural layer that increases the resistance of the flexible pipe to internal and external pressure and mechanical crushing loads. The layer also structurally supports the internal pressure sheath. In a preferred embodiment, the pressure armour layer 103 is formed from the thermoplastic composite described herein.

(9) The flexible pipe body also includes an optional first tensile armour layer 105 and optional second tensile armour layer 106. Each tensile armour layer is used to sustain tensile loads and internal pressure. The tensile armour layer is often formed from a plurality of (e.g. metallic) wires (to impart strength to the layer) that are located over an inner layer and are helically wound along the length of the pipe at a lay angle typically between about 10° to 55°. The tensile armour layers are often counter-wound in pairs. The tensile armour layers are often metallic layers, formed from carbon steel, for example. The tensile armour layers could also be formed from composite, polymer, or other material, or a combination of materials.

(10) The flexible pipe body shown also includes optional layers of tape 104 which help contain underlying layers and to some extent prevent abrasion between adjacent layers, or indeed as an outer surface of the flexible pipe in areas which may experience abrasion during service. The tape layer may be a polymer or composite or a combination of materials. The tape layer 104 may be formed of the thermoplastic composite described herein.

(11) The flexible pipe body also typically includes optional layers of insulation 107 and an outer sheath 108, which comprises a polymer layer used to protect the pipe against penetration of seawater and other external environments, corrosion, abrasion and mechanical damage.

(12) Each flexible pipe comprises at least one portion, sometimes referred to as a segment or section of pipe body 100 together with an end fitting located at at least one end of the flexible pipe. An end fitting provides a mechanical device which forms the transition between the flexible pipe body and a connector. The different pipe layers as shown, for example, in FIG. 1 are terminated in the end fitting in such a way as to transfer the load between the flexible pipe and the connector.

(13) FIG. 2 illustrates a riser assembly 200 suitable for transporting production fluid such as oil and/or gas and/or water from a sub-sea location 201 to a floating facility. For example, in FIG. 2 the sub-sea location 201 includes a sub-sea flow line. The flexible flow line 205 comprises a flexible pipe, wholly or in part, resting on the sea floor 204 or buried below the sea floor and used in a static application. The floating facility may be provided by a platform and/or buoy or, as illustrated in FIG. 2, a ship 200. The riser assembly 200 is provided as a flexible riser, that is to say a flexible pipe 203 connecting the ship to the sea floor installation. The flexible pipe may be in segments of flexible pipe body with connecting end fittings.

(14) It will be appreciated that there are different types of riser, as is well-known by those skilled in the art. Embodiments of the present invention may be used with any type of riser, such as a freely suspended (free, catenary riser), a riser restrained to some extent (buoys, chains), totally restrained riser or enclosed in a tube (I or J tubes).

(15) FIG. 2 also illustrates how portions of flexible pipe can be utilised as a flow line 205 or jumper 206.

(16) It will be clear to a person skilled in the art that features described in relation to any of the embodiments described above can be applicable interchangeably between the different embodiments. The embodiments described above are examples to illustrate various features of the invention.

(17) Throughout the description and claims of this specification, the words “comprise” and “contain” and variations of them mean “including but not limited to”, and they are not intended to (and do not) exclude other moieties, additives, components, integers or steps. Throughout the description and claims of this specification, the singular encompasses the plural unless the context otherwise requires. In particular, where the indefinite article is used, the specification is to be understood as contemplating plurality as well as singularity, unless the context requires otherwise.

(18) Features, integers, characteristics, compounds, chemical moieties or groups described in conjunction with a particular aspect, embodiment or example of the invention are to be understood to be applicable to any other aspect, embodiment or example described herein unless incompatible therewith. All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive. The invention is not restricted to the details of any foregoing embodiments. The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

(19) The reader's attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.