GB2366344A

GB2366344A - Hose

Info

Publication number: GB2366344A
Application number: GB0014350A
Authority: GB
Inventors: Matthew Vernon Ridolfi; Eric Joseph Davis; Gerard Anthony Hall; Simon Peter Alexander Thorp; Joel Aron Witz; Raymond Nicholas Burke
Original assignee: BHP Petroleum Pty Ltd
Current assignee: BHP Petroleum Pty Ltd
Priority date: 2000-06-12
Filing date: 2000-06-12
Publication date: 2002-03-06
Anticipated expiration: 2020-06-12
Also published as: GB2366347A; GB2366347B; GB2366344B; GB0014350D0; GB0109012D0

Abstract

A hose 10 comprises a tubular body 12 of flexible material arranged between an inner and an outer helically wound wire 22,24. The hose 10 further comprises a cured resin matrix (26a, figure 3) forming part of an insulation layer 26 within which the outer wire 24 is at least partially embedded. The matrix (26a, figure 3), improves the flexing capabilities of the hose, as it helps to maintain the outer wire 24 in the correct position. The resin matrix (26a, figure 3) is preferably a polyurethane. The hose 10 is preferably used for transporting cryogenic fluids.

Description

<Desc/Clms Page number 1> HOSE HAVING IMPROVED FLEXING CAPABILITIES This invention relates to hose. More particularly, the invention relates to hose having improved flexing capabilities. The invention is especially concerned with hose which can be used in cryogenic conditions.

Typical applications for hose involve the pumping of fluids from a fluid reservoir under pressure. Examples include suppling of domestic heating oil or LPG to a boiler; transporting produced oilfield liquids and/or gases from a fixed or floating production platform to the cargo hold of a ship, or from a ship cargo hold to a land-based storage unit; delivering of fuel to racing cars, especially during refuelling in formula 1; and conveying corrosive fluids, such as sulphuric acid.

It is well known to use hose for the transport of fluids, such as liquefied gases, at low temperature. Such hose is commonly used to transport liquefied gases such as liquefied natural gas (LNG) and liquefied propane gas (LPG).

In order for the hose to be sufficiently flexible, any given length must be at least partially constructed of flexible materials, i.e., non-rigid materials.

The structure of such hose generally comprises a tubular body of flexible material arranged between an inner and outer helically wound retaining wires. It is conventional for the two wires to be wound at the same pitch, but to have the windings displaced by half a pitch width from one another. The tubular body typically comprises inner and outer layers with an intermediate sealing layer. The inner and outer layers provide the structure with the strength to carry the fluid therein. Conventionally, the inner and outer layers of the tubular body comprise fabric layers formed of a polyester such as polyethylene terephthalate. The intermediate sealing layer provides a seal to prevent the fluid from penetrating the hose, and is typically a polymeric film.

The retaining wires are typically applied under tension around the inside and outside surfaces of the tubular body. The retaining wires act primarily to preserve the geometry of the tubular body. Furthermore, the outer wire may act to restrain excessive hoop deformation of the hose under high pressure. The inner and outer wires may also act to resist crushing of the hose.

A hose of this general type is described in European patent publication no. 0076540A1. The hose described in this specification includes an intermediate layer of

biaxially oriented polypropylene, which is said to improve the ability of the hose to resist the fatigue caused by repeated flexing.

In hose of this type it is important that the wires are maintained in the correct position. In general the inner and outer helical wires are longitudinally displaced relative to one another by a distance equal to about half a pitch length. This arrangement has been found to provide the best structural integrity. However, one of the problems with this sort of hose is that repeated flexing can cause the coils of the wire to be displaced out of the proper alignment.

We have now found a way to improve the flexing capabilities of the hose. Broadly, our invention involves providing a means to hold the outer wires in position, without compromising the flexing abilities of the hose.

According to one aspect of the invention we provide a hose comprising a tubular body of flexible material arranged between inner and outer gripping members, characterised by a cured resin matrix disposed around the tubular body, the outer gripping members being at least partially embedded in the resin matrix in order to restrict relative movement between the outer gripping members and the rest of the hose.

The cured resin matrix must have sufficient flexibility to allow the hose to bend to the extent that is required for the specific applications of the hose. Clearly, some applications may require more flexibility than others.

The resin matrix preferably comprises a synthetic polymer, such as polyurethane. It is especially preferred that the resin matrix is made of a material that, prior to curing, is capable of being applied in liquid form to the hose. Typically, the uncured resin may be applied to the hose by spraying, pouring or painting. This enables the uncured resin to be applied over the outer surface of the tubular body and the outer gripping members, and then cured in-situ to form a solid, flexible coating. The mechanism of curing may be light, moisture, etc.

The resin matrix may bond to a layer under the outer gripping member and also to any layer provided on the outer surface of the resin matrix. It is preferred that at least one of the layers adjacent the cured resin matrix is capable of withstanding cryogenic temperatures, so that, if the resin matrix cracks owing to the cryogenic temperatures, the adjacent layer holds the resin matrix together by virtue of the adhesion between the

resin matrix and the adjacent layer. The most stable structure is achieved when both sides of the resin matrix are bonded to adjacent layers.

We have also found that certain materials can provide hose with especially good insulation, particularly at cryogenic temperatures, In particular, we have found that fabrics formed of basalt fibres provide particularly good insulation.

Thus, according to another aspect of the invention we provide a hose comprising a tubular body of flexible material arranged between inner and outer gripping members, and an insulation layer disposed around the tubular body, characterised in that the insulation layer includes a fabric formed of basalt fibres.

Suitable basalt fibre fabrics are available from the Sudaglass Fiber Company under the trade designations BT-5, BT-8, BT-10, BT-11 and BT-13. The preferred thickness of the fabric is from about 0.1 mm up to about 0.3 mm. If desired, a plurality of layers of the basalt fabric may be employed.

We have also found that the insulation properties of basalt fabrics improve under compression, therefore we prefer to provide a compression layer around the basalt fabric, which serves to compress the basalt layer.

The insulation layer may further include layers made of other insulation material, such as polymeric foams, in addition to the layer(s) of basalt fabric.

We prefer that the insulation layer further includes at least one reinforcement layer, The reinforcement layer may comprise a synthetic polymer, such as a polyester, a polyamide or a polyolefin. The reinforcement layer may be made of the same materials as the inner and outer reinforcing layers of the tubular body, which are

described below. It is particularly preferred that the reinforcement layer of the insulation @C1.TM, layer is an ultra hgh molecular weight polyethylene (UHMWPE), such as DYNEEMA A CR.-c or SPECTRA as described below. The materials of construction of the tubular body should be selected to enable the hose to perform in the environment for which it is intended. Thus, there is a need for the hose to be able to transport pressurised fluids therethrough without leakage of the fluid through the walls of the hose. There is also a need for the hose to withstand repeated flexing, and to withstand the axial stresses caused by the combination of the hose and fluid weight. Also, if the hose is intended for use in transporting cryogenic fluids, the materials should be capable of operating at extremely cold temperatures

without any significant reduction in performance.

The tubular body preferably comprises at least one reinforcing layer and at least one sealing layer. More preferably, there are at least two reinforcing layers with the sealing layer sandwiched therebetween.

The main purpose of the or each reinforcing layer is to withstand the hoop stresses which the hose is subjected to during transport of fluids therethrough. Thus, any reinforcing layer which has the required degree of flexibility, and which can withstand the necessary stresses, will be adequate. Also, if the hose is intended for transporting cryogenic fluids, then the or each reinforcing layer must be able to withstand cryogenic temperatures.

We prefer that the or each reinforcing layer is formed of a sheet of material which has been wound into a tubular form by winding the sheet material in a helical manner. This means that the or each reinforcing layer does not have much resistance to axial tension, as the application of an axial force will tend to pull the windings apart. The or each reinforcing layer may comprise a single continuous layer of the sheet material, or may comprise two or more single continuous layers of the sheet material. However, more usually (and depending on the length of the hose) the or each layer of the sheet material would be formed of a plurality of separate lengths of sheet material arranged along the length of the hose.

In the preferred embodiment each reinforcing layer comprises a fabric, most preferably a woven fabric. The or each reinforcing layer may be a natural or synthetic material. The or each reinforcing layer is conveniently formed of a synthetic polymer, such as a polyester, a polyamide or a polyolefin. The synthetic polymer may be provided in the form of fibres, or a yarn, from which the fabric is created.

When the or each reinforcing layer comprises a polyester, then it is preferably polyethylene terephthalate.

When the or each reinforcing layer comprises a polyamide, then it may be an aliphatic polyamide, such as a nylon, or it may be an aromatic polyamide, such as an aramid compound. For example, the or each reinforcing layer may be a poly-(p- phenyleneterephthalamide) such as KEVLAR (registered trade mark).

When the or each reinforcing layer comprises a polyolefin, then it may be a polyethylene, polypropylene or polybutylene homopolymer, or a copolymer or

terpolymer thereof, and is preferably monoaxially or biaxially oriented. More preferably, the polyolefin is a polyethylene, and most preferably the polyethylene is a high molecular weight polyethylene, especially UHMWPE.

The UHMWPE used in the present invention would generally have a weight average molecular weight above 400,000, typically above 800, 000, and usually above 1,000,000. The weight average molecular weight would not usually exceed about 15,000,000. The UHMWPE is preferably characterised by a molecular weight from about 1,000,000 to 6,000,000. The UHMWPE most useful in the present invention is highly oriented and would usually have been stretched at least 2-5 times in one direction and at least 10-15 times in the other direction.

The UHMWPE most useful in the present invention will generally have a parallel orientation greater than 80%, more usually greater than 90%, and preferably greater than 95%. The crystallinity will generally be greater than 50%, more usually greaterthan 70%. A crystallinity up to 85-90% is possible.

UHMWPE is described in, for example, US-A-4344908, US-A-4411845, US-A- 4422993, US-A-4430383, US-A-4436689, EP-A-183285, EP-A-0438831, and EP-A- 0215507.

It is particularly advantageous that the or each reinforcing layer comprises a

highly oriented UHMWPE, such as that available from DSM High Peqormance Fibres CZMh BV (a Netherlands company) under the trade name DYNEEM4 or that available from the US corporation AlliedSignal Inc. under the trade name SPECTRA. CZT rt) Additional details about DYNEEMAjare disclosed in a trade brochure entitleo "DYNEEMA; the top performance in fibers; properties and application" issued by a SMm) High Performance Fibers BV, edition 02/98. Additional details about SPECTRAAare disclosed in a trade brochure entitled "Spectra Performance Materials" issued by AlliedSignal Inc., edition 5/96. These materials have been available since the 1980s.

The purpose of the sealing layer is primarily to prevent the leakage of transported fluids through the tubular body. Thus, any sealing layer which has the required degree of flexibility, and which can provide the desired sealing function, will be adequate. Also, if the hose is intended fortransporting cryogenic fluids, then the sealing layer must be able to withstand cryogenic temperatures.

The sealing layer may be made from the same basic materials as the or each

reinforcing layer. As an alternative, the sealing layer may be a fluoropolymer, such as: polytetrafluoroethylene (PFTE); a fluorinated ethylene propylene copolymer, such as a copolymer of hexafluoropropylene and tetrafluoroethylene (tetrafluoroethylene- perfluoropropylene) availablefrom DuPont Fluoroproducts underthetrade name Teflon FEP; or a fluorinated hydrocarbon - perfluoralkoxy - available from DuPont Fluoroproducts under the trade name Teflon PFA. These films may be made by extrusion or by blowing.

Since the sealing layer is intended to provide a sealing function, the sealing layer should be provided in the form of a film which is substantially impermeable to the transported fluids.

We prefer that the sealing layer is formed of a sheet of material which has been wound into a tubular form by winding the sheet material in a helical manner. As with the reinforcing layers, this means that the or each sealing layer does not have much resistance to axial tension, as the application of an axial force will tend to pull the windings apart. The sealing layer may comprise a single continuous layer of the sheet material, or may comprise two or more single continuous layers of the sheet material. However, more usually (and depending on the length of the hose) the or each layer of the sheet material would be formed of a plurality of separate lengths of sheet material arranged along the length of the hose. If desired the sealing layer may comprise one or more heat shrinkable sealing sleeves (i.e. tubular in form) which are arranged over the inner reinforcing layer.

We prefer that the sealing layer comprises a plurality of overlapping layers of film. Preferably there would be a: least 2 layers, more preferably at least 5 layers, and still more preferably at least 10 layers. In practice, the sealing layer may comprise 20, 30, 40, 50, or more layers of film. The upper limit for the number of layers depends upon the overall size of the hose, but it is unlikely that more than 100 layers would be required. Usually, 50 layers, at most, will be sufficient: The thickness of each layer of film would typically be in the range 50 to 100 micrometres.

It will, of course, be appreciated that more than one sealing layer may be provided.

One suitable sealing layer is described in our copending UK patent application of even date entitled "Hose incorporating an improved Sealing Layer".

The tubular body may further include one or more insulation layers made of conventional insulation material and/or made of the basalt fibre fabric described above.

It is preferred that the hose is also provided with an axial strengthening means as described in our copending United Kingdom patent application of even date entitled "Hose Having Improved Axial Strength". The axial strengthening means may also serve as the compression layer.

The gripping members typically each comprise a helically wound wire. The helices of the wires are typically arranged such that they are offset from one another by a distance corresponding to half the pitch of the helices. The purpose of the wires is to grip the tubular body firmly therebetween to keep the layers of the tubular body intact and to provide structural integrity for the hose. The inner and outer wires may be, for example, mild steel, austenitic stainless steel or aluminium. If desired, the wires may be galvanised or coated with a polymer.

It will be appreciated that although the wires making up the gripping members may have a considerable tensile strength, the arrangement of the wires in coils means that the gripping members can deform when subjected to relatively small axial tension. Any significant deformation in the coils will quickly destroy the structural integrity of the hose.

According to another aspect of the invention there is provided a method of making a hose comprising: (a) wrapping a wire around a tubular mandrel to form an inner coil; (b) wrapping a sheet material around the tubular mandrel and the inner coil order to provide a tubular body formed of the sheet material; (c) wrapping a wire around the tubular body to form an outer coil; (d) applying a curable liquid resin over the outer surface of the tubular body and the outer wire; (e) allowing the resin to cure; (f) securing the ends of the hose produced in step (e); and (g) removing the hose from the mandrel.

Preferably, the method further comprises applying an insulation layer over the cured resin. The insulation layer preferably comprises a fabric formed of basalt fibres, as described above.

In step (c), the tubular body may comprise a tubular body as described above. In particular, the tubular body may include one or more insulation layers made of conventional insulation material and/or made of the basalt fibre fabric described above.

The hose according to the invention can be provided for use in a wide variety of conditions, such as temperatures above 100 C, temperatures from 0 C to 100 C and temperatures below 0 C. With a suitable choice of material, the hose can be used at temperatures below -20 C, below -50 C or even below -100 C. For example, for LNG transport, the hose may have to operate at temperatures down to -170 C, or even lower. Furthermore, it is also contemplated that the hose may be used to transport liquid oxygen (bp -183 C) or liquid nitrogen (bp -196 C), in which case the hose may need to operate at temperatures of -200 C or lower.

The hose according to the invention can also be provided for use at a variety of different duties. Typically, the inner diameter of the hose would range from about 2 inches (51 mm) to about 24 inches (610 mm), more typically from about 8 inches (203 mm) to about 16 inches (406 mm). In general, the operating pressure of the hose would be in the range from about 500 kPa gauge up to about 2000 kPa gauge, or possibly up to about 2500 kPa gauge. These pressures relate to the operating pressure of the hose, not the burst pressure (which must be several times greater). The volumetric flow rate depends upon the fluid medium, the pressure and the inner diameter. Flowrates from 1000 m3/h up to 12000 m3/h are typical.

The hose according to the invention can also be provided for use with corrosive materials, such as strong acids, Reference is now made to the accompanying drawings, in which: Figure 1 is a schematic diagram showing the principle stresses to which the hose according to the invention may be subjected in operation; Figure 2 is a schematic cross-sectional view of a hose according to the invention; and Figure 3 shows an insulation layer of the hose of Figure 2; in greater detail. Figure 1 shows the stresses to which a hose H is normally subjected to during use. The hoop stress is designated by the arrows HS and is the stress that acts tangentially to the periphery of the hose H. The axial stress is designated by the arrows AS and is the stress which acts axially along the length of the hose H. The flexing stress

is designated FS and is the stress which acts transverse to the longitudinal axis of the hose H when it is flexed. The torsional stress is designated TS and is a twisting stress which acts about the longitudinal axis of the hose. The crushing stress is designated CS and results from loads applied radially to the exterior of the hose H.

The hoop stress HS is generated by the pressure of the fluid in the hose H. The axial stress AS is generated by the pressure of the fluid in the hose and also by the combination of the weight of the fluid in the hose H and by the weight of the hose H itself. The flexing stress FS is caused by the requirement to bend the hose H in order to position it properly, and by movement of the hose H during use. The torsional stress TS is caused by twisting of the hose.

The present invention is primarily concerned with improving the resistance of hose to the flexing stress FS. In Figure 2 a hose in accordance with the invention is generally designated 10. In order to improve the clarity the winding of the various layers in Figure 2, and in the other Figures, has not been shown.

In Figure 2 a hose in accordance with the invention is generally designated 10. The hose 10 comprises a tubular body 12 which comprises an inner reinforcing layer 14, an outer reinforcing layer 16, and a sealing layer 18 sandwiched between the layers 14 and 16.

The tubular body 12 is disposed between an inner helically coiled wire 22 and an outer helically coiled wire 24. The inner and outer wires 22 and 24 are disposed so that they are offset from one another by a distance corresponding to half the pitch length of the helix of the coils. An insulation layer 26 is disposed around the outer wire 24.

The reinforcing layers 14 and 16 comprise woven fabrics of a synthetic material, such as aramid fibres. The sealing layer 18 comprises a plurality of layers of plastics film which are wrapped around the outer surface of the inner reinforcing layer 14 to provide a fluid tight seal between the inner and outer reinforcing layers 14 and 16.

Figure 3 shows the insulation layer 26 in greater detail. The insulation layer 26 comprises an inner layer 26a which is formed of a polyurethane which has been sprayed, poured, or otherwise applied, over the tubular body 12 and the outer wire 24. After hardening, the polyurethane layer 26a forms a solid matrix within which the outer wire 24 is embedded. This helps to keep the outer wire 24 fixed in position.

The insulation layer 26 includes a layer 26b over the layer 26a. The layer 26b comprises a fabric formed of basalt fibres. The layer 26b provides most of the insulating properties of the hose 10.

The insulation layer 26 further includes a layer 26c over the layer 26b. The layer [ic,TM)- crtxr#) 26c comprises an UHMWPE such as DYNEEMA@ior SPECTRA The purpose of the layer 26c is primarily to provide strengthening against hoop and flexing stresses. Finally, the insulation layer 26 further includes a compression layer 26d. The purpose of the compression layer 26d is to compress the layer 26b, as we have found that the insulation properties of the basalt fabric layer 26b are much improved under compression. The compression layer 26d may, for example, comprise a rope or cord which is wrapped tightly around the layer 26c. Preferably, the compression layer 26d comprises an axial strengthening layer as described in our copending United Kingdom patent application of even date entitled "Hose Having Improved Axial Strength".

The hose 10 can be manufactured by the following technique. As a first step the inner wire 22 is wound around a support mandrel (not shown), in order to provide a helical arrangement having a desired pitch. The diameter of the support mandrel corresponds to the desired internal diameter of the hose 10. The inner reinforcing layer 14 is then wrapped around the inner wire 22 and the support mandrel. A plurality of layers of the plastics film making up the sealing layer 18 are then wrapped around the outer surface of the inner reinforcing layer 14. The outer reinforcing layer 16 is then wrapped around the sealing layer 18. The outer wire 24 is then wrapped around the tubular member 20, in order to provide a helical arrangement having a desired pitch. The pitch of the outer wire 24 would normally be the same as the pitch of the inner wire 22, and the position of the wire 24 would normally be such that the coils of the wire 24 are offset from the coils of the wire 22 by a distance corresponding to half a pitch length; this is illustrated in Figure 2, where the pitch length is designated p. A polyurethane resin is then be sprayed over the outer surface of the outer reinforcing layer 16 to form a resin coating over the outer reinforcing layer 16 and the outer wire 24. The resin may then be left to harden, in order to form the layer 26a. The basalt fabric layer 26b is then wrapped around the polyurethane layer 26a, and the UHMWPE layer 26c is then wrapped around the layer 26b. Finally, the compression layer 26d is applied over the layer 26c.

The ends of the hose 10 may be sealed by crimping a sleeve onto an insert inside the hose 10. This termination is generally applied after the hose 10 as been removed from the mandrel. An improved technique for sealing the ends of the hose 10 is disclosed in our copending United Kingdom patent applications of even date entitled "End Fitting for a Hose" and "End Fitting Having Improved Sealing Capabilities".

It will be appreciated that the invention described above may be modified.

Claims

CLAIMS: 1. A hose comprising a tubular body of flexible material arranged between inner and outer helically wound wires, characterised by a cured resin matrix disposed around the tubular body, the outer wire being at least partially embedded in the resin matrix in order to restrict relative movement between the outer wire and the rest of the hose.
2. A hose according to claim 2, wherein the uncured resin forming the resin matrix is a material which can be applied to the tubular member in liquid form.
3. A hose according to claim 1 or 2, wherein the resin matrix is a polyurethane.
4. A hose according to any preceding claim, further comprising an insulation layer comprising a fabric formed of basalt fibres.
5. A hose according to claim 4, further comprising a compression layer around the basalt fabric, which serves to compress the basalt fabric.
6. A hose according to claim 5, wherein the compression layer comprises an ultra high molecular weight polyethylene.
7. A hose according to any preceding claim, wherein the tubular body comprises at least one reinforcing layer and at least one sealing layer.
8. A hose according to claim 7, wherein the tubular body comprises two of said reinforcing layers with the sealing layer sandwiched therebetween.
9. A hose according to claim 7 or 8, wherein the or each reinforcing layer comprises an ultra high molecular weight polyethylene.
10. A hose according to claim 7, 8 or 9, wherein the sealing layer comprises an ultra high molecular weight polyethylene or a fluoropolymer.

<Desc/Clms Page number 13>
11. A method of making a hose comprising: (a) wrapping a wire around a tubular mandrel to form an inner coil; (b) wrapping a sheet material around the tubular mandrel and the inner coil order to provide a tubular body formed of the sheet material; (c) wrapping a wire around the tubular body to form an outer coil; (d) applying a curable liquid resin over the outer surface of the tubular body and the outer wire; (e) allowing the resin to cure; (f) securing the ends of the hose produced in step (e); and (g) removing the hose from the mandrel.
12. A method according to claim 11, further comprising applying an insulation layer over the cured resin.
13. A method according to claim 12, wherein the insulation layer comprises a fabric formed of basalt fibres.
14. The use of a hose according to any one of claims 1 to 10 to transport fluids at cryogenic temperatures therethrough.
15. A hose substantially as herein described with reference to and as shown in the accompanying drawings.
16. A method of making a hose substantially as herein described with reference to and as shown in the accompanying drawings.