NO336326B1 - End fitting for a hose, hose and method for making a hose - Google Patents

Description

The present invention relates to an end fitting for a hose, a hose and a method for producing a hose, as can be seen from the introductory part of patent claims 1, 10 and 15 respectively.

Background

Typical applications for hoses involve pumping fluid from a fluid reservoir under pressure. Examples include supplying light fuel oil or LPG to a boiler; transport produced oilfield fluids and/or gases from a fixed or floating production platform to the hold of a ship, or from a hold of a ship to a land-based storage unit; supply fuel to racing cars, especially during refueling in Formula 1; and transport of corrosive fluids, such as sulfuric acid.

It is known to use hoses for the transport of fluid, such as liquefied gas at low temperature. Such hoses are usually used for the transport of liquefied gases such as LNG (condensed methane mixture) and LPG (condensed hydrocarbon gas).

For the hose to be sufficiently flexible, any given length must be at least partially constructed of flexible materials, that is, non-rigid materials.

The construction of the hose generally comprises a tubular body of flexible material arranged between an inner and outer helically bonded supporting wire. It is common for two strands to be tied with the same pitch, but to have the windings offset by half a pitch's width apart. The tubular body typically comprises inner and outer layers with a barrier layer in between. The inner and outer layers provide a structure with the strength to carry the fluid in it. Typically, the inner and outer layers of the tubular body comprise fabric layers formed from a polyester, such as polyethylene terephthalate. The barrier layer in between provides a barrier to prevent the fluid from penetrating the hose, and is usually a polymer film.

The supporting threads are generally applied under tension around the inner and outer surfaces of the tubular body. Furthermore, the outer thread can function to limit undue deformation of the hose under high pressure. The inner and outer threads can also act to resist pinching the hose.

A hose of this common type is described in European Patent Publication 0076540A1. The hose described in this specification includes an interlayer of biaxially oriented polypropylene, which is said to improve the ability of the hose to resist material fatigue caused by repeated bending.

Another hose is described in GB 2223817A. The hose described in this publication is a composite hose comprising an inner helical metal core, a plurality of layers of plastics material fibers and films bonded to the core, at least one layer of glass cloth and at least one layer of aluminum foil placed close together and bonded to the plastic material, and an outer spiral-shaped metal form. This hose is said to be suitable for transporting flammable fuels and oils.

Another hose is described in GB 1034956 A. This hose is an electrical hose or channel, that is to say it is intended for carrying electrical cables rather than transporting fluid. As a result, the considerations involved in this design are completely different to the considerations involved in the tubing described in EP 0076540A1 and GB 2223817A. The hose described in GB 2223817 A comprises: (i) an internally arranged helically bonded thread; (ii) an extruded neoprene tube surrounding the inner thread; (iii) a braided metal sheath surrounding the neoprene tubing; (iv) a nylon cord applied helically to the sheath;

(v) a cloth wrapped around the nylon cord and sheath; and

(vi) an outer helically bonded thread arranged around the cloth wrap.

The braided metal jacket is made to follow the winding of the inner thread by further temporarily tying a thread around the jacket during the manufacture of the hose.

GB 323352 describes a pipe coupling for use with flexible externally reinforced hoses.

Many hose applications require the hose to be supported along its length. This particularly applies to the transport of produced liquids and/or gases as mentioned above. Without additional support, conventional hoses are often unable to support their own weight or the weight of the fluid contained therein.

The present invention also relates to an improvement in the termination of the ends of the hose.

The invention

According to one aspect of the invention, an end fitting for a hose has been provided, according to the characterizing part of patent claim 1.

According to another aspect of the invention, a hose has been provided which incorporates the end fitting, as appears from the characterizing part of patent claim 10.

According to another aspect of the invention, a method for producing a hose incorporating the end fitting is indicated, as appears from the characterizing part of patent claim 15.

Further features of the invention appear from the respective independent claims.

Further preferred features of the hose incorporating the end fitting will now be described.

The hose preferably comprises a tubular body of flexible material which is arranged between inner and outer gripping means, where the hose further comprises an axial strengthening means adapted to reduce the deformation of the tubular body when the tubular body is subjected to axial stress, and the axial strengthening means is further adapted to exert a radially inward force on at least portions of the tubular body when the axial reinforcing means is subjected to axial stress. In a particularly preferred embodiment, the failure stress for the tubular body and the axial reinforcing means is in the range of 1% to 10%. More preferably, the error voltage is in excess of 50% at ambient and cryogenic temperatures.

By means of this arrangement, the axial reinforcing means improves the ability of the hose to withstand axial stresses, and at the same time may contribute to the structural integrity of the hose under axial stress by pressing against at least portions of the tubular body. In addition, the materials of the tubular body and the axial strengthening means are preferably so compatible that they each behave in the same way during operation, so that no single component is subjected to unreasonable stresses and strains. This means that the materials of the tubular body and the axial reinforcement respond to pre-tension in a similar way. A bending strain (for a cylindrical component) of at least 3% is generally required for the type of hose applications contemplated for the present invention. While the intervening strip and straightening of the helically oriented components will compensate for some of this misalignment, there will still be a resultant prestretch of the order of 1% following those components of the tubing wall. This compares to a typical resulting strain of 0.2% for metals.

It is particularly preferred that the axial reinforcing means is made of a non-metallic material, particularly a plastic material - suitable materials are discussed in detail below. This is because metallic materials probably do not have the desired prestretch properties.

It is preferred that the tubular body and the axial reinforcing means comprise the same material, preferably ultra-high molecular weight polyethylene (UHMWPE), as described further in detail below.

The tubular body preferably comprises at least one reinforcement layer and at least one barrier layer. It is even more preferred that there are at least two reinforcement layers with the barrier layer in between.

Preferably, a further reinforcement layer is provided between the outer gripping member and the axial reinforcement means.

The maximum strength of the reinforcement layer or layers is preferably between 100 and 700 kN for a hose diameter of 200 mm. It is preferred that the bending strain in case of failure of the reinforcing layer or layers is in the range of 2% to 15%. It is further desirable that the reinforcement layer or layers are of the same material as the axial reinforcement, preferably UHMWPE.

Preferably, the axial reinforcing means comprises a substantially tubular jacket formed from a layer material provided in tubular form, so that the jacket can maintain the integrity of its tubular shape when subjected to axial stress. The hose may be provided with two or more jackets to further improve the performance of the hose under axial tension.

In a particularly advantageous embodiment, the axial reinforcing means is provided in the form of a substantially tubular braid. In this specification, the term "braid" refers to a material formed from two or more fibers or yarns that are braided together to form an elongated structure. It is a characteristic of braids that they can be elongated when subjected to an axial tension. It is a further property of braids that when provided in tubular form, the diameter will decrease when the braid is subjected to axial tension. In this manner, by providing a tubular braid around the tubular body, or within the structure of the tubular body, the braid will exert a radially inward force on at least portions of the tubular body when subjected to axial tension.

It is preferred that the entire tubular sheath is provided in the form of a braid. However, it is possible that only one or some of the parts of the length of the tubular sheath are provided in the form of a braid.

It is also preferred that the braid extends all the way around the circumference of the tubular sheath. However, it is possible that only parts of the circumference of the tubular sheath are provided in the form of the braid.

The braid can be produced in biaxial form (that is, where the braid is formed from only two twisted fibers or yarns) or in triaxial form (that is, where there are also fibers or yarns that extend in the longitudinal direction, for increased axial strength).

Although it is preferred to provide the axial reinforcing means in the form of a braid, it can be provided in other forms that meet the functional requirements mentioned above. In this way, the reinforcing means can be provided as a suitable arrangement of tape or rope wrapped spirally around a tubular body.

The materials for the construction of the hose should be chosen so that it is possible for the hose to function in the environment for which it is intended. Therefore, there is a need for the hose to be able to transport fluid under pressure without leakage of fluid through the walls of the hose. There is also a need for the hose to withstand repeated bending, and to withstand the axial stresses caused by the combination of hose and fluid weight. If the hose is intended for the transport of cryogenic fluids, the materials should also be able to be used at extremely low temperatures without significant reduction in performance.

The main purpose of that or each of the reinforcement layers is to withstand the band stresses to which the hose is exposed during the transport of fluid. Thus, any reinforcement layer which has the required degree of flexibility and which can withstand the required stresses will be suitable.

If the hose is also intended for the transport of cryogenic fluids, then the reinforcement layer or layers must be able to resist/tolerate cryogenic temperatures.

We prefer that the or each of the reinforcement layers is formed from a layer material which is bound in a tubular shape by winding the layer material in a spiral fashion. This means that it or each of the reinforcing layers does not have as much resistance to axial tension, as the application of an axial force will tend to pull the windings apart. The or each of the reinforcement layers may comprise a single continuous layer of sheet material, or may comprise two or more simple layers of layer material. However, typically (and depending on the length of the tubing) the or each layer of sheet material will be formed from a plurality of separate lengths of sheet material arranged along the length of the tubing.

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

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

When the or each reinforcing layer comprises a polyamide, it may be an aliphatic polyamide, such as nylon, or it may be an aromatic polyamide, such as an aramid composition. For example, the reinforcement layer may be a poly-(phenylene terephthalamide), such as KEVLAR (registered trademark).

When it or each reinforcing layer comprises a polyolefin, it can be a polyethylene, polypropylene or polybutylene homopolymer, or a copolymer or terpolymer of this type, and is preferably monoaxially or biaxially oriented. Even more preferred is if the polyolefin is a polyethylene, and most preferred is if the polyethylene is a high molecular weight polyethylene, especially UHMWPE.

The UHMWPE used in this invention will 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 will usually not exceed 15,000,000. UHMWPE is preferably characterized as having a molecular weight of from about 1,000,000 to 6,000 000. The UHMWPE most useful in the present invention is highly aligned and will 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 alignment greater than 80%, more typically greater than 90% and preferably greater than 95%. The crystallinity will generally be greater than 50%, more usually greater than 70%. A crystallinity of up to 85-90% is possible.

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

It is particularly advantageous that the reinforcing layer(s) comprise an oriented UHMWPE, such as is available from DSM High Performance Fibers BV (a Dutch company) under the trade mark DYNEEMA, or available from the American company AlliedSignal Inc, under the trade mark SPECTRA.

Additional details on DYNEEMA are shown in the brochure entitled "DYNEEMA; the top performance in fibers; properties and application" published by DSM High Performance Fibers BV, issue 02/98. Additional details on SPECTRA are shown in a brochure entitled "Spectra Performance Materials" published by AlliedSignal Inc., Issue 5/96. These materials have been available since the 1980s.

In the preferred embodiment, the reinforcing layer comprises a woven fabric formed of fibers arranged in a "weft and warp" direction. We have found that this is particularly advantageous if the reinforcement layer is arranged so that the warp direction of the fabric is at an angle of less than 20° to the axial direction of the hose; we also prefer this angle to be greater than 5°. In the preferred embodiment, the reinforcement layer is arranged so that the warp direction of the fabric is at an angle between 10° and 20°, preferably 15° in relation to the axial direction of the hose.

The purpose of the barrier layer is primarily to avoid leakage of transported fluid through the tubular body. In this way, any barrier layer which has the appropriate degree of flexibility and which can provide the desired barrier function will be suitable. Even if the hose is intended to transport cryogenic fluids, the barrier layer must be able to withstand cryogenic temperatures.

The barrier layer may be made of the same basic materials as the reinforcement layer. Alternatively, the barrier layer may be made of a fluoropolymer, such as: polytetrafluoroethylene (PFTE); fluoroethylene propylene copolymer, such as a copolymer of hexafluoropropylene and tetrafluoroethylene (tetrafluoroethylene perfluoropropylene) available from DuPont Fluoroproducts under the trademark Teflon REP; or fluorohydrocarbon-perfluorooxy - available from DuPont Fluoroproducts under the trademark Teflon PFA. These films can be made by extrusion or by blowing.

We prefer that the barrier layer is formed from a sheet material that has been spun into a tubular shape by rolling the material in a spiral fashion. As with the reinforcement layers, this means that the barrier layer does not have much resistance to axial tension, as the application of an axial force will try to pull the windings apart. The barrier layer may comprise a single continuous layer of the layer material, or may comprise two or more simple continuous layers of the layer material. However, and more commonly (and depending on the length of the tubing), each layer of sheet material is formed from a plurality of separate lengths of sheet material arranged along the length of the tubing. If desired, the barrier layer may comprise one or more heat-shrinkable barrier sleeves (ie in tubular form) which are arranged over the inner reinforcement layer.

We prefer that the barrier layer includes a majority of overlying layers. Preferably there will be at least two layers, more preferably at least five layers and even more preferably 10 layers. In practice, the barrier layer will comprise 20, 30, 40, 50 or more layers of film. The upper limit of the number of layers depends on the overall size of the hose, but it is unlikely that more than 100 layers will be required. Usually 50 layers will be sufficient. The thickness of each layer will typically be in the range of 50 to 100 micrometres.

The axial reinforcement may also be made of the same material as the reinforcement layer. It is therefore clear that the axial reinforcing means, the reinforcing layers and the barrier layer can be made of the same basic compound. However, the shape of the connection must be different to provide the desired function, that is, the axial reinforcing means provides axial reinforcement, the or each of the reinforcing layers provides reinforcement against band stresses, and the barrier layer provides a barrier function. We have found UHMWPE materials to be most suitable, especially the DYNEEMA and SPECTRA products. These materials have also been found to perform well under cryogenic conditions. The preferred parameters of UHMWPE (molecular weight range, etc.) discussed above in connection with the reinforcing layers are also appropriate for the axial reinforcing means. In this context, however, it should be noted that the parameters for the UHMWPE used in the axial reinforcement do not have to be the same as the parameters for the UHMWPE used in the reinforcement layers.

It will be possible for the axial reinforcing means to be provided in the layers of the tubular body. However, we prefer that the axial reinforcing means is positioned between the tubular body and the outer gripping member. In another preferred embodiment, the axial reinforcement means is provided within the layers of the tubular body, and a further axial reinforcement means is also provided between the tubular body and the outer gripping member.

When the tubing is intended for cryogenic applications, it is desirable to provide insulation over the tubular body. The insulation can be provided between the outer wire and the tubular sheath and/or on the outside of the outer wire. The insulation may comprise material commonly used to provide insulation in cryogenic equipment, such as a synthetic foam material. It is preferred that the axial reinforcing means is provided around the insulation layer to compress the insulation layer and maintain their structural integrity. The axial reinforcement around the insulation layer is preferably provided in addition to the axial reinforcement between the outer gripping member and the tubular body. A particularly suitable form of insulation is provided in detail below.

The hose according to the invention can further comprise an insulating layer. The tubing may further comprise a hardened resin matrix disposed around the outer thread, wherein the outer thread is at least partially enveloped in the resin matrix to limit relative movement between the outer thread and the remainder of the tubing. The uncured resin constituting the resin matrix may be a material such as polyurethane, which may be applied to the tubular member in liquid form

In one embodiment, the hose additionally comprises an insulating layer comprising a substance formed from basalt fibres. A compression layer can be provided around the basalt material, which serves to compress the basalt material. The compression layer may comprise ultra-high molecular weight polyethylene.

In one embodiment, the hose additionally comprises a layer of plastic material around the tubular body, where the plastic material comprises gas bubbles in the same. Plastic material may be applied to the tubular body by spraying the plastic material in liquid form over the surface of the tubular body followed by curing. The gas bubbles can be incorporated by injecting the gas into the plastic material before spraying, while it is still in liquid form. The hose may additionally comprise a further layer of plastic material, which does not contain any significant amounts of gas bubbles, arranged over the gaseous plastic material; this further layer of plastic material may be polyurethane.

In one embodiment, the snake has a specific gravity of less than 0.8.

A separate end fitting can of course be applied to each end of the hose.

It is possible for the hose to be removed from the spindle before the end fitting is placed inside it. Alternatively, the end fitting can be placed inside the rest of the tubing by sliding the inner spindle up and along to one end of the tubing, then attaching the rest of the tubing to the end fitting while the end fitting and the rest of the tubing remain on the spindle.

In the above-described aspects of the invention, each of the gripping members typically comprises a spirally bound wire. The spiral of the threads is typically arranged so that they are offset from each other by a distance corresponding to half the pitch of the spiral. The purpose of the threads is to grip the tubular body firmly in between to keep the layers of the tubular body intact and to provide structural integrity for the tubing. The inner and outer threads can be, for example, mild steel, austenitic stainless steel or aluminium. If desired, the wires can be galvanized or covered with a polymer.

It will be appreciated that although the threads which make up the gripping means may have considerable tensile strength, the arrangement of the threads in the rolls means that the gripping means can deform when subjected to relatively small axial stresses. Any significant deformation of the rollers will quickly destroy the structural integrity of the hose.

The hose according to the invention can be provided for use under many changing environments, such as temperatures above 100 °C, temperatures from 0 °C - 100 °C and temperatures below 0 °C. With the appropriate choice of materials, the hose can be used below -20 °C, below 50 °C and also below 100 °C. For example, for LNG transport, the hose may have to be operated at temperatures below -170 °C, or even lower. Furthermore, it is also assumed that the hose can be used to transport liquid oxygen (boiling point -183 °C) or liquid nitrogen (boiling point -196 °C), where the hose in these cases must be operated at temperatures of -200 °C or lower.

The hose according to the invention can also be provided for a number of other services. Typically, the inner diameter of the hose will vary from 51 mm to 610 mm, more typically from 203 mm to 406 mm. In general, the operating pressure in the hose will be in the range of 500 KPa up to 2000 kPa, or perhaps also up to around 2500 kPa. These pressures are related to the operating pressure in the hose, not the burst pressure (which must be several times greater). The volumetric flow rate depends on the fluid medium, the pressure and the internal diameter. Flow rates from 1000 m<3>/n to 12,000 m<3>/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 attached drawings, where:

Fig. 1 is a schematic diagram showing the principal stresses to which the hose according to the invention can be subjected in operation; Fig. 2 is a schematic cross-section of a hose in accordance with the invention; Fig. 3 is a section showing the arrangement with a reinforcement layer in the hose in accordance with the invention; Fig. 4A is a section showing the arrangement with a tubular axial reinforcement jacket of the hose, where the axial reinforcement jacket is in the loosened position; Fig. 4B is a section showing the arrangement with a tubular axial reinforcement jacket of the hose, where the axial reinforcement jacket is in a tightened position; Figures 5A, 5B, 5C and 5D show four applications of the hose in accordance with the invention; Fig. 6 is a cross-section showing the barrier layer of the hose;

Fig. 7 is a cross-section showing an insulation layer in the hose in fig. 2 in detail; and

Fig. 8 is a schematic cross-section of an end fitting for a hose in accordance with the invention.

Fig. 1 shows the stresses to which a hose H is usually exposed in use. The strip stress is marked with the arrows HS and are the stresses that act tangentially on the periphery of the hose H. The axial stress is marked FS and are the stresses that act across the longitudinal axis of the hose H when it is bent. The torsional stress is marked TS and is the twisting stress that acts about the longitudinal axis of the hose. The compressive stress is marked CS and results from the load applied radially on the outside of the hose H.

The band tension HS is generated by the pressure of the fluid in the hose H. The axial tension 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 the weight of the hose H itself. The bending 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. Known hoses are usually able to withstand band stresses HS, bending stresses FS and torsional stresses TS, but are less able to withstand axial stresses AS. For this reason, known hoses have usually had to be supported when subjected to axial stresses AS in order to minimize the axial stresses AS.

The problem of resisting the axial stresses AS is solved by the present invention. In fig. 2, a hose in accordance with the invention is marked 10. To improve clarity, the winding of the various layers in fig. 2 and in the other figures, not shown.

The hose 10 comprises a tubular body 12 comprising an inner reinforcement layer 14, an outer reinforcement layer 16, a barrier layer 18 between the layers 14 and 16. A substantially tubular jacket 20, which improves axial strength, is placed around the outer surface of the outer reinforcement layer 16.

The tubular body 12 and the tubular jacket 20 are placed between an inner spirally coiled thread 22 and an outer helically coiled thread 24. The inner and outer threads 22 and 24 are positioned so that they are offset from each other by a distance corresponding to half a pitch length for the spiral angle of the rollers.

An insulating layer 26 is placed around the outer wire 24. The insulating layer can be a common insulating material, such as plastic foam, or can be a material described below in relation to fig. 7.

The reinforcement layers 14 and 16 comprise woven fabrics or a synthetic material, such as UHMWPE or aramid fibres. Fig. 3 illustrates the inner reinforcement layer 14, where it can be seen that the inner reinforcement layer 14 comprises fibers 14a arranged in the warp direction W and fibers 14b arranged in the weft direction F. In fig. 3, only layer 14 is shown, to improve clarity. We have unexpectedly found that the axial reinforcement of the hose 10 can be improved by arranging the reinforcement layer 14 so that the warp direction W has a low angle of less than 20°C and typically around 15°C to the longitudinal axis of the hose 10. This angle is marked with a in fig. 3 The structure and direction of the outer reinforcement layer 16 is substantially identical to the inner reinforcement layer 14; the angle a for the outer reinforcement layer 16 can be the same as, or different from, the angle a for the inner reinforcement layer 14.

The barrier layer 18 comprises a plurality of layers of plastic film wrapped around the outer surface of the inner reinforcement layer 14 to provide a fluid tight barrier between the outer and inner reinforcement layers 14 and 16.

The hose 10 further comprises a reinforcement layer 21 placed between the jacket 20 and the outer threads 24. The reinforcement layer 21 can have similar characteristics to the jacket 20 and the tubular body 12.

The tubular sheath 20 is formed from two sets of fibers 20a and 20b, which are braided to form a tubular braid. This is shown in fig. 4A and 4B - in these figures only the tubular sheath 20 is shown to improve clarity. There are spaces 28 between the sets of fibers 20a and 20b so that when the tubular jacket 20 is subjected to axial tension, the fibers 20a and 20b can contract by moving into the spaces 28. This works in a way to try to reducing the diameter of the tubular jacket 20, which causes it to tighten around the tubular body 12, again increasing the structural integrity and burst pressure of the hose 10. Fig. 4B shows the tubular jacket 20 in a tightened condition.

The barrier layer 18 is shown in greater detail in fig. 6. The acquisition of the barrier layer 18 improves the resistance of the hose to bending stresses FS and band stresses HS.

As shown in fig. 6, the barrier layer 18 comprises a plurality of layers 18a of a film made of a first polymer (such as highly oriented UHMWPE) interspersed with a plurality of layers 18b of a film made of a second polymer (such as PFTE or FEP), where the two the polymers have different stiffness. The layers 18a and 18b are wrapped around the outer surface of the inner reinforcement layer 14 to provide a fluid tight barrier between the inner and outer reinforcement layers 14 and 16. As mentioned above, the layers 18a and 18b need not necessarily be arranged in an alternating manner. For example, all layers 18a may be arranged together, and all layers 18b may be arranged together.

The insulation layer 26 is shown in greater detail in fig. 7, which shows the insulation layer 26 in greater detail. The insulation layer is primarily concerned with improving the hose's resistance to the bending stresses FS and with insulating the hose.

The insulating layer 26 comprises an inner layer 26a which is formed of a polyurethane that is sprayed, completely or otherwise applied over the tubular body 12 and the outer thread 24. After curing, the polyurethane layer 26a forms a solid matrix in which the outer thread 24 is incorporated . This helps to keep the outer thread 24 in a fixed position.

The insulation layer 26 comprises a layer 26b above the layer 26a. Layer 26b comprises a material formed from basalt fibres. The layer 26b provides most of the insulating properties of the hose 10.

The insulation layer 26 further comprises a layer 26c above the layer 26b. The layer 26c comprises a UHMWPE such as DYNEEMA or SPECTRA. The purpose of layer 26c is primarily to improve the reinforcement against band stresses and bending stresses.

The insulation layer 26 further comprises a compression layer 26d. The purpose of the compression layer 26d is to compress the layer 26b, as we have found that the insulating properties of the basalt fiber layer 26b are greatly improved under compression. The compression layer 26d can, for example, comprise a rope or string that is wrapped tightly around the layer 26c. Preferably, the compression layer 26d comprises an axial reinforcement jacket like the jacket 20 described above.

A further layer (not shown) containing gas bubbles may be provided over the layer 26 to further improve the insulation and buoyancy properties of the hose 10. A further polyurethane layer (not shown) which does not contain gas bubbles may be provided over the gas containing polyurethane layer. The further polyurethane layer can additionally, or instead, be provided in layer 26d. It is also possible that the layer 26a itself contains gas bubbles.

The hose 10 can be produced by the following technique. As a first step, the inner thread 22 is wound around a support spindle (not shown) to provide a helical arrangement with a desired pitch. The diameter of the support spindle corresponds to the desired inner diameter of the hose 10. The inner reinforcement layer 14 is then wrapped around the inner thread 22 and the support spindle, so that the warp direction W is set to the desired angle a.

A plurality of layers of plastic films 18a and 18b constituting the barrier layer 18 are then wrapped around the outer surface of the inner reinforcement layer 14. Typically, the films 18a and 18b will have a length substantially less than the length of the hose 10, so that a plurality of separate lengths of the films 18a and 18b will have to be wrapped around the inner layer 14. The films 18a and 18b are preferably arranged in an alternating manner through the thickness of the barrier layer 18. Typically there may be five separate layers of films 18a and 18b through the thickness of the barrier layer.

The outer reinforcement layer 16 is then wrapped around the barrier layer 18, so that the warp direction E is set to the desired angle (which may be a, or another angle close to a). The tubular reinforcement jacket 20 is pulled over the outside of the outer reinforcement layer 16. The further reinforcement layer 21 is then wrapped around the jacket 20.

The outer thread 24 is then wrapped around the further reinforcement layer 21 to provide a helical arrangement with a desired pitch. The pitch of the outer thread 24 will normally be the same as the pitch of the inner thread 22, and the position of the thread 24 will normally be such that the rollers on the thread 24 are offset from the rollers on the thread 22 by a distance corresponding to half the pitch length, this is shown in fig. 2, where the rise length is marked with p.

A polyurethane resin is then sprayed over the outer surface of the reinforcing layer 21 to form a resin coating over the reinforcing layer 21 and the outer thread 24. The resin can then be left to cure to form the layer 26A. The resin can be aerated before curing (typically before spraying or painting, in order to create gas bubbles in it). The base layer 26b is then wrapped around the polyurethane layer 26a, and the UHMWPE layer 26c is then wrapped around the layer 26c.

The ends of the hose 10 can be blocked by crimping a sleeve on an insert on the inside of the hose 10. This termination is generally done after the hose 10 has been removed from the spindle.

The ends of the hose 10 can be blocked using the end fitting 200 as shown in fig. 8. In fig. 8, the hose 10 is not shown to improve clarity. The end fitting 200 comprises a tubular inner member 202 with a hose end 202a and a tail end 202b. The end fitting 200 further comprises a locking device comprising a PTFE locking ring 204 and a split ring 206 of stainless steel around the PTFE locking ring 204.

The end fitting 200 further comprises a load transferring means comprising a hose engaging member 208, a load transferring member 210 and an end member in the form of a disc-shaped plate 212. The load transferring member comprises a disc-shaped plate 214 and at least one load transferring rod 216. In fig. 2 there are two of the rods 216, but it is possible to provide three or more of the rods 216. A tightening nut 218 is provided on each rod 216. The plates 212 and 214 respectively have openings 212a and 214a to receive the rods 216.

The plates 212 and 214 may be a Simon plate, the hose engaging member 202 may be a Gedring and the split ring 206 may be an Ericring.

The plate 212 is further provided with openings 212b and the tail end 202b of the inner member 202 is provided with openings 202c. Attachment bolts 220 extend through openings 202b and 212b to attach plate 212 to tail end 202a of inner member 202.1 fig. 2 there are two fastening bolts 220 and associated openings, but it would be appreciated if fewer or more fastening bolts 220 and associated openings could be provided.

The hose engaging member 208 is provided with internal helical recesses in the form of grooves 208a adapted to receive the outer thread 24 of the hose 10. The internal member 202 is provided with an outer helical recess in the form of grooves 202d adapted to receive the inner thread 22 in itself. It will be seen from fig. 2 that, as with the inner and outer threads 22 and 24, the grooves 208a and 202d have spaces with one and a half pitch lengths p.

The inner member 202 is provided with two projections 202e around the circumference, which are located below the barrier 204. The projections 202e serve to improve the blocking of the tubular member 20 between the inner member 202 and the barrier 204, and help to prevent the tubular member from in default is pulled out of position.

The hose 10 is attached to the end fitting 200 as follows. The inner member 202 is threaded into the end of the hose 10, so that the hose 10 lies close to the plate 212. The inner thread 22 is received in the grooves 202d and the outer thread 24 is received in the grooves 208a. The inner and outer threads 22 and 24 are shortened so that they do not extend along the inner member 202 beyond the grooves 202d and 208a. The insulation 26 is also shortened to this point. The inner reinforcement layer 14 is also cut back at this point or at a point before the inner reinforcement layer 14 reaches the barrier 204. This means that the barrier layer 18 directly engages the outer surface of the inner member 202. However, the rest of the tubular body 12 is allowed to extend along the inner member 202 between the inner member 202 and the locking ring 204.

The hose engaging member 208 is then tightened to cause it to clamp down on the hose 10 to bring it firmly into engagement with the hose 10. The nuts 218 are then tightened, which induces some axial tension in the hose 10, thereby taking up slack in the system. These forces are transmitted to the hose engaging member 208, to the plate 214, to the rod 216, to the plate 212 and to the tail end 202b of the inner member 202. The tubular member 20 is retracted over the upper surface of the hose engaging member 208 and attached to the projections 208b extending from the upper surface of the hose engaging member 208.

The tubular body 12 extends below the locking ring 204. After the hose engaging member 208 and nuts 218 are tightened, the split ring 206 is tightened to increase the force applied to the tubular body 12 by the locking ring 204.

The end fitting 200 is then cooled to a low temperature with liquid nitrogen. This causes the locking ring 204 to contract more than the splitting ring 206, whereby the compression force applied to the locking ring 204 by the splitting ring 206 is reduced. While the split ring 206 and the locking ring 204 are at a relatively low temperature, the split ring 206 is tightened again. The temperature is then allowed to rise to ambient temperature, whereby the compression force on the locking ring increases due to greater expansion of the locking ring 204 relative to the splitting ring 206.

This completes the end fitting for the hose 10. The hose engaging member 208 provides some locking of the end of the hose 208 and helps to take axial forces in the hose 10 around the locking ring 204. The locking ring 204 provides the remaining locking of the hose 10.

Figs. 5A to 5D show three uses for the hose 10. In each of Figs. 5A to 5C, a floating production, storage and offloading (FPSO) vessel 102 is connected to an LNG tanker 104 by means of a hose 10 in accordance with the invention. The hose 10 transports LNG from a storage tank at the FPSO 102 to a storage tank at the LNG tanker 104. In fig. 5A, the hose is above sea level 106. In fig. 5b, the hose 10 is lowered below sea level 106. In fig. 5c the snake floats near the surface of the sea. In each case, the hose carries 10 LNG without intermediate support. In fig. 5d, the LNG tanker is connected to a land-based storage facility 108 via the hose 10.

The hose 10 can be used for many other applications than shown in fig. 5a - 5c. The hose can be used in cryogenic and non-cryogenic environments.

It will be appreciated that the invention can be modified. For example, the tubular sheath 20 may be located on the outside of the outer thread 24. The hose 10 may also comprise additional reinforcing layers 14, 18, barrier layers 16 and/or tubular sheaths 20. One or more of, or all, the barrier layers 18a may be a polymer-coated metallic film, or metallized polymer film. In the same way, one or more of, or all, the barrier layers 18b can be polymer-covered metallic film, or metallized polymer film.

Claims (18)

1. End fitting (200) for terminating an end of a hose (10) comprising a tubular body (12) of flexible material arranged between inner and outer gripping means (22,24), whereby the end fitting comprises: an inner member (202) adapted to to be placed at least partially inside the hose; a locking member (204,206) adapted to lock at least portions of the tubular body completely around the circumference between the locking member and the inner member; and a separate load transferring means (208,210,212) adapted to transfer axial loads applied to the hose around the locking member to reduce or eliminate the axial load on the hose between the locking member and the inner member, characterized in that the locking member comprises an inner locking ring (204) and an outer split ( 206) which can be tightened to force the lock into engagement with the tubular body and internal organ. 2. End fitting in accordance with claim 1, wherein the inner member is substantially cylindrical, and the locking member is in the form of a ring adapted to receive the inner member, so that the tubular body can be clamped between the outer surface of the inner member and the inner surface of the ring. 3. End fitting in accordance with patent claim 1 or 2, where the split is made of stainless steel and the locking ring is polytetrafluoroethylene. 4. End fitting in accordance with one of claims 1 to 3, wherein the load transferring means comprises a hose engaging member (208), a load transferring member (210) and an end member (212), attached to the inner member, the arrangement being such that the locking member is placed between the load transmitting member and the end member, and that the hose engaging member and the end member are connected via the load transferring member. 5. End fitting in accordance with patent claim 4, where the hose engaging member is adapted to engage the hose in such a way that at least parts of the axial forces inside the hose are transferred from the hose to the hose engaging member. 6. End fitting in accordance with claim 4 or 5, wherein the load transmitting means comprises a load transmitting plate (214) with an opening (212b) adapted to receive the hose, the plate having a surface capable of engaging the hose engaging means, whereby load can be transferred from the hose engaging member to the plate. 7. End fitting in accordance with patent claim 6, where the load-transmitting member further comprises a load-transmitting rod (216) attached between the plate and the end member for transferring load from the plate to the end member. 8. An end fitting according to one of claims 1 to 7, wherein the inner member has a hose end (202a) adapted to extend within an end portion of the hose, and a tail portion (202b) remote from the hose end, and wherein the end portion is arranged on one side of the locking member near the tail ends, and the hose engaging member is arranged on the other side of the locking member near the hose end. 9. End fitting in accordance with one of claims 1 to 8, whereby the locking member is adapted to seal against the tubular body regardless of the application of axial load between the hose and the inner member. 10. Hose comprising a tubular body of flexible material arranged between an inner and an outer spirally wound wire, where the tubular body serves to transport fluid through the hose and to avoid fluid leakage through the body, characterized in that the hose further comprises an end fitting in accordance with one of patent claims 1 to 8 adapted to the end thereof. 11. A hose in accordance with claim 10, wherein the hose engaging means is adapted to secure a part of the hose which is folded back over an outer part of the hose engaging means. 12. Hose in accordance with patent claim 11, further comprising an axial reinforcement member in the form of a braid (20) around the tubular body, and where the braid is the part of the hose that is folded back over the outer part of the tubular body. 13. Hose according to one of claims 10 to 12, wherein the tubular body extends between the inner member and the blocking member. 14. Hose in accordance with one of the patent claims 10 to 13, where the tubular body comprises at least one reinforcement layer and at least one barrier layer. 15. A method of making a hose, comprising: (a) wrapping a thread around a tubular mandrel so as to form an inner roll; (b) wrapping a sheet material around the tubular mandrel and the inner roll to provide a tubular body formed from the sheet material; (c) wrapping a thread around the tubular body so as to form an outer roll; and (d) removing the tube from the spindle; characterized by the following steps: (e) placing an internal member in an open end of the tube; (f) clamping a load transferring member on an outer surface of the hose; and (g) clamping a locking member comprising an inner locking ring and an outer split to an outer surface of the tubular body, and tightening the split to force the sealing ring into engagement with the tubular body and the inner member. 16. Method according to claim 15, whereby the load transmitting member serves to transfer axial loads applied between the hose and the internal member in such a way that the axial loads are redirected around the locking member to reduce, or eliminate, any axial load on the hose between the locking member and the inner member, and whereby in step (g) the clamping of the locking member to the outer surface of the tubular body seals the locking member against the tubular body regardless of the application of axial loads between the hose and the inner member. 17. Method according to patent claim 15 or 16, further comprising the following steps between steps (b) and (c): (h) pulling a tubular axial reinforcement member over a free end of the spindle, so that the spindle extends within the axial reinforcement member, for then drawing the axial reinforcement member along the spindle so that it at least partially covers the tubular body. 18. A method in accordance with claim 17, wherein the axial reinforcement member is clamped by means of the load transmitting member, and further comprising the following steps after step (f): (i) folding back the tubular axial reinforcement member over a portion of the axial reinforcement means.