Cryogenic fluid transfer

Abstract

A hose comprises a tubular inner hose 1 for fluid transport and an outer hose part 4. The tubular inner hose has a corrugated inner surface defining a bore of the inner hose. The inner hose further co

Description

FIELD OF THE INVENTION The present invention relates to cryogenic fluid transfer. In embodiments, the present invention provides methods and apparatus for effective transfer of cryogenic fluids. DESCRIPTION OF THE RELATED ART Cryogenic fluid transfer techniques have been used for some time in relation to subsea pipelines. Originally, this use was driven by the desire to obtain natural gas from remote locations. A large amount of natural gas (mainly methane) is present in remote locations around the world. This gas is of significant value if it can be economically marketed. If the stored gas is reasonably close to the places where it is to be consumed and the terrain between the locations allows, then the gas is generally extracted and transported in gaseous form to those end locations. Transportation is achieved via underwater and / or onshore pipelines. However, if gas is produced where it is not economically feasible or where it is not permitted to lay a pipeline, then other techniques to transport the gas need to be employed. A commonly used technique for transporting gas without a pipeline is to liquefy the gas at or near the production site and then to transfer the liquefied gas into a specially designed storage tank on a carrier, such as a ship. Liquefying the gas significantly reduces its volume and increases the mass of gas that can be stored and transported. In order to achieve this, the natural gas is cooled and condensed to a liquid state to produce liquefied natural gas (LNG). LNG is typically (but not always) stored and transported at substantially atmospheric pressure and at a temperature of about -162 0 C. When an LNG carrier arrives at a destination, typically the LNG is unloaded into other storage tanks. A regassification processes is then performed, as needed, to convert the LNG back into gaseous form, after which it may be transported, for example via pipelines, to end locations to be used. LNG is an increasingly popular transportation method for supplying natural gas to major energy consuming countries. The piping used to transport liquefied gases, such as LNG or the liquefied components of air, must be capable of withstanding very low temperatures, typically below -150°C. One type of piping used for such transport is a reeled corrugated hose with a vacuum between an inner and an outer corrugated hose. Transfer of LNG is not the only use case for cryogenic fluid transfer, however. An increasingly important use of such hoses is in connection with superconducting cabling. There are now superconducting materials available that are capable of superconducting operation (with significant current flow) at liquid nitrogen temperatures, and which can be manufactured as structurally stable tapes or wires - examples of such materials are BisSraCaaCuaOio (BSCCO) with a critical temperature of -160°C and YBa2Cu3O? (YBCO) with a critical temperature of -180°C. Hoses of the type indicated above may be used to convey liquid nitrogen to support such superconducting uses. However, such hoses may also be used for superconducting cables in use. Reeled corrugated hoses manufactured from stainless steel are an established means of transporting cryogenic fluids - stainless steel hoses can be used to carry fluids at such temperatures without becoming brittle. Figures 1 and 2 show a prior art hose of this type (such hoses are provided, for example, by Nexans). The cryogenic fluid is carried within a corrugated stainless steel inner tube 1. This tube is longitudinally welded to form desired hose lengths. The inner tube 1 is surrounded by a number of layers 2 of superinsulation - individual layers are separated by a polypropylene spacer fleece (not shown). A low loss spacer 3 holds the inner tube 1 in position and a vacuum layer 5 is defined between the insulated inner tube 1 and a further corrugated stainless steel outer tube 4, also longitudinally welded to form a desired hose length. This outer tube 4 is retained within a protective outer polyethylene jacket 6. The tubes shown here are helically corrugated, although in other embodiments corrugations may be circular and not helical. Figure 3 shows an example of how this arrangement can be used in connection with superconducting cable 8 (comprising, for example, superconducting wire in a sheath). Using a hose of this type with a flow of liquid nitrogen in the central bore of the hose enables the superconducting cable to be kept at operating temperature even if the outer jacket of the hose is at ambient temperature. While such hose structures are robust and can achieve well insulated cryogenic flow, another technical problem arises. Fluid flow through the inner hose can easily become turbulent, and there are significant friction effects between the transported liquid and the hose. Agitation and turbulence can also lead to ‘boil off’, in which the liquid changes phase to gas. Such gas must then be either consumed, re-liquified (at significant cost) or vented (which may be environmentally damaging) This can lead to use of such corrugated hoses becoming problematic in certain conditions. It is against this background that the present invention has been devised. SUMMARY OF THE INVENTION According to a first aspect, the invention provides a hose for fluid transfer, the hose comprising a tubular inner hose for fluid transport and an outer hose part, wherein the tubular inner hose has a corrugated inner surface defining a bore of the inner hose, the inner hose further comprising a tubular sleeve located within the bore of the inner hose, wherein an inner wall of the tubular sleeve is substantially smooth, wherein the tubular sleeve has a longitudinally extending slot and wherein an outer wall of the tubular sleeve forms a compression fit with the corrugated inner surface of the inner hose. Using such an approach, flow of fluid - such as cryogenic fluid - within the inner hose can be stabilized by the smooth inner wall of the liner and the permeation of fluid into the corrugations, but without movement of the liner as the liner is held in place by its compression fit with the inner hose. This longitudinally extending slot may extend along the whole length of the tubular sleeve. In such a case, the tubular sleeve may extend along substantially the whole bore of the inner hose. The slot may have a uniform width along the length of the tubular hose. The slot may have a width of 0.67 to 2 per cent of a circumference of the tubular sleeve. The tubular sleeve may be formed of a single polymer composite. The tubular sleeve may comprise polypropylene, or may comprise polyetherimide. The tubular sleeve may comprise a carbon reinforcement. In embodiments, the tubular sleeve may be between 1 and 2 mm in thickness. In embodiments, the tubular sleeve may be formed with a diameter greater than the diameter of the bore of the inner hose, wherein the tubular sleeve is radially compressed for insertion into the inner hose, and wherein a restoring force to expand the tubular sleeve to its formed size provides a compression fit with the corrugated inner surface of the inner hose. Using this approach, a liner with the necessary properties to stabilize fluid flow within the inner hose can be formed simply, and fabrication of the lined hose itself is also straightforward. Hoses of this type may be adapted for flow of cryogenic fluids. In such cases, the inner hose may be wrapped in one or more layers of superinsulation. The tubular inner hose may have both corrugated inner and outer surfaces, and the tubular inner hose may be located within an outer hose part bore, with a corrugated inner surface of the outer hose part defining the outer hose part bore. The outer hose part bore may then be adapted to provide a vacuum space between the outer hose part and the inner hose. According to a second aspect, the invention provides insulated superconducting cable comprising a hose for fluid transfer as described in the first aspect, with a superconducting cable disposed within the inner permeable tubular sleeve such that the inner hose is adapted for a conveying a low temperature fluid in the bore of the inner hose for cooling the superconducting cable. According to a third aspect, the invention provides the use of a hose for fluid transfer according to the first aspect for conveying a fluid having a temperature below -150°C. According to a fourth aspect, the invention provides a method of lining a hose for fluid transfer, the hose comprising a tubular inner hose for fluid transport and an outer hose part, wherein the tubular inner hose has a corrugated inner surface defining a bore of the inner hose, the method comprising: forming a longitudinal slot in a length of tubing having a diameter greater than a diameter of the bore of the inner hose; compressing the length of slotted tubing radially to pass into the bore of the inner hose; and passing the length of slotted tubing into the bore of the inner hose to form a tubular sleeve as a liner for the bore of the inner hose, wherein an inner wall of the tubular sleeve is substantially smooth, wherein the tubular sleeve has a longitudinally extending slot and wherein an outer wall of the tubular sleeve forms a compression fit with the corrugated inner surface of the inner hose. Compressing the length of slotted tubing radially may comprise passing the length of slotted tubing through a forming cone. In one approach, compressing the length of slotted tubing radially may comprise compressing the length of slotted tubing to substantially the diameter of the bore of the inner hose, and passing the length of slotted tubing into the bore of the inner hose may comprise moving the length of slotted tubing against friction with the corrugated inner surface. In another approach, compressing the length of slotted tubing radially may comprise compressing the length of slotted tubing to a new diameter less than the diameter of the bore of the inner hose, retaining the length of slotted tubing at the new diameter, passing the length of slotted tubing into the bore of the inner hose comprises moving the length of slotted tubing substantially without friction, and may then further comprise releasing the retaining of the length of slotted tubing at the new diameter when in a final position to provide the compression fit with the corrugated inner surface. The longitudinal slot may be formed by cutting the length of tubing with one or more knives. The lining of the hose may in some embodiment takes place in line with the manufacture of the hose. The longitudinally extending slot may be formed along a whole length of the slotted tubing. The tubing may be formed of a single polymer composite. In embodiments, the tubing may have a diameter greater than the diameter of the bore of the inner hose, wherein a restoring force to expand the tubular sleeve to its formed size then provides the compression fit with the corrugated inner surface of the inner hose. The diameter of the tubing may be 1.02 to 1.06 times the diameter of the bore of the inner hose. In embodiments, the hose may be adapted for flow of cryogenic fluids. In such a case, the inner hose may be wrapped in one or more layers of superinsulation. The tubular inner hose may have both corrugated inner and outer surfaces, and the tubular inner hose may be located within an outer hose part bore, with a corrugated inner surface of the outer hose part defining the outer hose part bore. The outer hose part bore may be adapted to provide a vacuum space between the outer hose part and the inner hose. According to a fifth aspect, the invention provides a method of manufacturing an insulating hose for a superconducting cable, comprising manufacturing and lining a hose according to the fourth aspect, and disposing a superconducting cable disposed within the inner permeable tubular sleeve such that the inner hose is adapted for a conveying a low temperature fluid in the bore of the inner hose for cooling the superconducting cable. BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be further described, by way of example only, and with reference to the accompanying drawings, in which: Figure 1 shows a view of separate layers of a corrugated hose known in the prior art; Figure 2 shows a longitudinal sectional view of the corrugated hose of Figure 1; Figure 3 shows a corrugated hose of the type shown in Figures 1 and 2 adapted for carrying a superconducting cable; Figure 4 shows a modified corrugated hose, with an internal liner, according to an embodiment of the invention; Figure 5 shows an internal liner according to an embodiment of the invention before insertion into a corrugated hose; Figure 6 shows a corrugated hose according to an embodiment of the invention with the internal liner of Figure 5 inserted; Figures 7A and 7B show different views on inserting an inner sleeve into a corrugated hose in accordance with an embodiment of the invention; Figure 8 shows apparatus for constructing a corrugated hose with an inner sleeve according to an embodiment of the invention; Figure 9 shows a process of compressing an inner sleeve for insertion into a corrugated hose in accordance with an embodiment of the invention; Figures 10A to 10C show a first method of assembling a corrugated hose with an inner sleeve according to embodiments of the invention; Figures 11A to 11C show a second method of assembling a corrugated hose with an inner sleeve according to embodiments of the invention; and Figure 12 illustrates compression forces in a liner as shown in Figure 5 into the corrugated hose of Figure 6 for different oversizes of liner. DETAILED DESCRIPTION A detailed description of the invention will now be provided with reference to the above figures. A given reference number is always used to denote the same feature in each of the accompanying drawings. Figure 4 shows the basic approach taken to address the issue of turbulent flow in the corrugated inner pipe. An inner sleeve or liner 7 is located within the corrugated inner pipe (hose) 1. This inner sleeve 7 has a substantially, or comparatively, smooth inner surface, and so does not create turbulence in the same way as the corrugated inner pipe 1. The inner sleeve 7 is here disposed so that the main flow of fluid takes place within the internal sleeve. However, it is not intended to form the boundary of the flow channel - it is desirable for the inner sleeve 7 to be permeable so that there is fluid disposed to either side of it, that is, as well as fluid flowing within the internal sleeve, there should be fluid in the corrugations of the inner hose. This prevents a pressure buildup which could cause the inner sleeve 7 to collapse. This can be achieved by formation of a longitudinally extending slot 9 along the length of the inner sleeve 7. This allows fluid to pass through the slot 9 into the corrugations of the inner hose, preventing the pressure imbalance. Location of the inner sleeve 7 within the inner hose may be challenging. One option is to attempt to locate the inner sleeve 7 with spacers, but pressure and fluctuations in the fluid flow may cause the inner sleeve 7 to move with respect to the corrugated inner pipe 1. This can lead to turbulence and other flow irregularities. This problem is addressed in embodiments of the invention by forming an oversized inner sleeve 7. When inserted into the corrugated inner pipe 1, such an inner sleeve 7 will form an compression fit with the corrugated inner pipe 1, holding it in place. Moving the inner sleeve 7 against this compression requires the force to be overcome, in a similar manner to an interference fit. To achieve this compression fit, the inner sleeve 7 is formed to be oversized for the inner bore of the corrugated inner pipe 1, and provided with an initial slot 9a - this is as shown in Figure 5. The initial slot 9a has a width wOpen significantly wider than the width Wciosed of the longitudinally extending slot 9 of the inner sleeve 7 when in place. This configuration is shown in Figure 6. The inner sleeve 7 is compressed to fit into the bore of the inner hose 1, at which point there is a compression fit between the outer wall of the inner sleeve 7 and the corrugated inner wall 11 of the corrugated inner pipe 1 and a reduced width slot 9 allowing fluid to permeate the corrugation zone 10 between the inside of the inner linerand the corrugations of the inner hose. As the slot 9 in the liner extends longitudinally, fluid will be able to permeate into the corrugation zone 10 whether the inner pipe is helically corrugated or circularly corrugated. Methods for formation of the inner liner 7 and its insertion into the inner hose 1 will be described further below. Using this approach, the issue of turbulence can be addressed effectively. As the main flow of fluid is along the smooth inner bore of the inner sleeve 7, turbulence is largely prevented. Otherwise, for cryogenic fluid flow along a long pipe - in practice, pipes of this type may be several kilometres in length - turbulence may be a significant limiting factor in the flow rate achievable through the pipe. While Figure 4 illustrates this approach in the context of the pure fluid carrying hose of Figure 1, it is equally applicable to the superconducting cable carrying hose of Figure 3 - here the superconducting cable will simply slide within the inner sleeve 7. The cable may be provided with periodic axial centralizers to keep the cable centralized within the inner pipe 1 and the inner sleeve 7. Another possible mechanism for providing superconducting cable in this arrangement is to wrap it around the inner corrugated pipe within the annulus under vacuum. As previously noted, a suitable corrugated hose structure for use with embodiments of the invention is known, and is shown in Figure 1 - further discussion of hoses of this general type may be found in, for example, US 2020 / 224816 A1 (Nexans) - and this will not be discussed in further detail here. Different types of internal sleeve 7 suitable for use in embodiments of the invention will now be described, together with methods for manufacturing such sleeves and for integrating them into a hose. The internal sleeve 7 needs to be manufacturable into a tube with a longitudinal slot, sufficiently elastic and resilient that it can be compressed for insertion into a corrugated inner hose, and capable of maintaining its structural integrity while adjacent to or surrounded by liquid nitrogen or a similarly cold fluid. Suitable materials may be single polymer composites (in which the same polymer, or a polymer of the same type, is provided as both a polymer matrix and a support) or other composites involving polymers with suitable thermal properties. Suitable polymers may be polypropylene (PP) or polyetherimide (PEI) - though other polymers, or polypropylene hybrid systems may be used, and carbon may be used as a reinforcement. With respect to liner tubing manufacture, a suitable method for manufacturing a composite pipe for transporting cryogenic fluid is set out in the applicant’s earlier UK Patent Application No. 2304622.0, the contents of which are incorporated by reference to the extent permitted by applicable law. For inclusion in a nominally 50mm diameter inner hose - with corrugations, the internal diameter will be slightly below 50mm - a suitable liner thickness would be 1-2 mm. Here, for satisfactory leakage between the inner surface of the liner and the corrugated region 10, the width Wciosed of the slot 9 after insertion should be 1 -3 mm. To achieve this width, the uncompressed liner 7 is formed with a width wOpen of 4-13mm - this equates an oversize of roughly 2-6% compared to the internal diameter of the inner hose. It should be noted that for the use cases indicated here, such as providing a hose for superconducting cable, the overall hose length may be from several metres to hundreds of metres. If the oversize is too low, this will result in an insufficiently strong compression fit with the inner surface of the inner hose, and the liner will move relative to the inner hose. If the oversize is too high, the frictional forces involved in insertion will be too great, and it will be too difficult to manufacture the lined inner hose - the forces required will either be impractically large or will create too great a risk of damage to the hose or the liner. This is particularly significant for longer lengths of hose (which may as indicated be 100m or significantly longer). Exemplary values are given in Table 1 below - this indicates requirements for a range of embodiments of the invention including a case close to a lower bound for oversize, a case close to an upper bound for oversize, and an intermediate case. Liner thickness (mm) % Oversized Oversize circumference (mm) Drag force per m (N) 100m total drag force (N) Open slot length (mm) Open slot length % of circumference Closed slot length (mm) Average Liner Tensile Stress (MPa) 1.5 2 155.5 29 2900 5.1 3.2 2.0 12.9 1.5 4 158.7 112 11200 8.3 5.2 2.0 49.6 1.5 6 161.8 200 20000 11.4 7.0 2.0 88.7 The strength of thecompression fit and the drag force required will be closely related (as that is effectively what the drag force is pulling against). The difference between the 2% oversize case, where the compression fit is barely sufficient, and the 6% oversize case, where the drag force required is too likely to cause damage, can be seen to be significant. Figure 12 illustrates the liner radial compression per metre for these three cases and the associated compression force. Insertion of such an inner sleeve 7 into the corrugated inner pipe 1 can be carried out by adapting known processes, such as pigging. Figures 7A and 7B show how pigging can be used to achieve insertion of an inner sleeve 7 into a corrugated inner pipe 1 of a corrugated hose. Pigs 111 (“pig” is a backronym for pipeline inspection gauge, or gadget) are commonly used for a variety of purposes in relation to pipelines - originally for inspection and maintenance, but other uses are known. The pig 111 is urged by pressure from one end of the pipeline to another - typically the pig 111 will be driven by compressed air or water. Here the pig 111 is used to insert the inner sleeve 7 in a two stage process. It is practical to fit the inner sleeve 7 this way as it has a clearance fit to the corrugated inner pipe 1, so the operation will not meet varied or excessive resistance. The pig 111 is attached to a cable 112, and then the pig 111 is driven (Figure 7A) through the corrugated inner pipe 1 by an appropriate pressure medium (for example compressed air, or water), pulling the cable 112 behind it. The cable 112 can then be used to drag (Figure 7B) the inner sleeve 7 through the corrugated inner with the drag force described above, and to position the ends of the inner sleeve 7 correctly with respect to the ends of the corrugated inner pipe 1 for final assembly. Manufacture of the inner sleeve 7 and its assembly into corrugated inner pipe 1 will now be described in more detail with reference to Figures 8 to 11. Figure 8 shows elements of a manufacturing system for forming an inner liner and inserting it into an inner hose of a pipe for carrying cryogenic fluid (sometimes described here as a cryostat - this is used particularly where the cryogenic fluid is used to cool another element within the cryostat, such as a superconducting cable). The inner liner 7 is formed from cylindrical tubing 86 of the appropriate material through any appropriate manufacturing mechanism - such as plastic extrusion - which is provided as in input to the process on a storage reel 84. This original tubing 86 is unreeled and passed through a cutting box 82, where the longitudinal slot is introduced into the tubing by an appropriate cutting mechanism 81. The slotted tubing is then passed into a forming cone 85, where it is introduced into the inner hose of the corrugated cryostat 83. The slotted tubing is attached (not shown) to a towline pulled by a winch 87, as shown in Figure 7B. As can be seen from Figure 8, the cutting of the slot can be achieved inline between the transport reel and before installation into the cryostat. This can be achieved by standard cutting methods - for example by saws, blades / knives (heated or unheated), lasers or waterjets, or any other established cutting method - and if carried out inline, appropriate tension for cutting can be maintained. The cutting process removes a longitudinally extending strip of material, resulting a length of uncompressed tubing with a longitudinally extending slot of predetermined width. Such a cutting mechanism will work irrespective of orientation to line along the pipe - the blades can be placed above the pipe in line for cutting the slot or underneath. For a single polymer composite, a hot knife would be a particularly suitable cutting mechanism - for a material containing significant carbon, a different form of blade may be used. Figure 9 shows a suitable approach for compressing the slotted uncompressed tubing for insertion into the cryostat. The slotted tubing 86’ with longitudinal slot 89’ is inserted (here, dragged) into the forming cone 85, at which point it is compressed to close the longitudinal slot 89’. The forming cone 85 bends the slotted tubing 86’ into a compressed tubing annulus 86”. In different arrangements here, the slot may be closed (with the cut walls of the compressed tubing annulus 86” abutting each other), one cut tubing wall may overlap another, or alternatively there may still be a slot present - though smaller. Common to all these approaches is that the outer diameter of the compressed tubing annulus 86” is sufficiently less than the inner diameter of the inner hose of the cryostat 83 that the compressed tubing annulus 86” can be pulled into the cryostat 83. Different methods of assembling the cryostat with an inner sleeve are available. These may also take place after the cryostat is otherwise assembled, or can take place as an intermediate step in the manufacture of the cryostat, or as an inline process directly after the manufacture of the cryostat. One exemplary method of tow (pigging to route a towline through the cryostat, followed by attachment of the towline to the inner sleeve for subsequent winched tow) is shown in Figures 7A and 7B, though it should be noted that pigging only and tow only processes are also possible. In any approach, the liner needs to be compressed at least to the point where its outer diameter is no more than the inner diameter of the inner hose so that the liner can enter the inner hose to be pulled through it. However, at this point there are (at least) two possible options: compression may be just sufficient for the liner to enter the inner hose so that it can be dragged through it against friction, or the liner may be compressed further so that it can be inserted without friction. These two cases are discussed below with respect to Figures 10A to 10C and Figures 11A to 11C respectively. In the first case as shown in Figures 10A to 10C, the cut edges 91 of the annulus forming the liner 86’ define the original slot 9a. As shown in Figure 10A, these cut edges 91 are brought together in the forming cone only sufficiently for the liner 86’ to enter the inner hose, so that the outer surface of the liner 86’ abuts the corrugations 93 of the inner hose, as shown in Figure 10B. The slot between the cut edges 91 reduces to essentially its final in-use dimension (slot 9) and the liner 86’ is pulled through the inner hose until it is its final position as shown in Figure 10C. The liner 86’ is now fully in position, and the only step required is to finish the ends of the lined inner hose (for example, but detaching the tow line or by cutting away the end part engaged with the tow line). In the second case as shown in Figures 11A to 11C, the cut edges 91 of the annulus forming the liner 86’ again define the original slot 9a. As shown in Figure 11 A, these cut edges 91 are brought together more closely, here so that the cut edges 91 abut, so that there is positive clearance between the outer surface of the liner 86’ and the corrugations 93 of the inner hose, as shown in Figure 11B. This may means such as a restrictor (not shown) to hold the liner 86’ in its compressed position, or centralizers (not shown) in the inner hose. The liner 86’ can now be pulled through as before, though this is now an easier process as there is no need to pull against tension between the outer edge of the liner 86’ and the corrugations 93. However, when in position, an additional step is needed to release the compressed tube so that it engages with the corrugations as shown in Figure 11C - the position at this point is essentially the same as for the first case (Figure 10C). On this release (by removal of restrictor, or of centralizers), the compressed liner 86’ springs back to a position where it is still compressed to some degree, with this providing frictional engagement with the corrugations, but where the slot 9 between the cut edges 91 has opened to its in-use dimension, which is sufficient to allow fluid to pass between the inner part of the inner hose and the volume adjacent to the corrugations 93. Using this approach, the cryogenic hose of Figure 3 (with inner sleeve 7) can be used for transfer of cryogenic fluid with the risk of turbulence effectively addressed. The smooth inner bore of the inner sleeve prevents turbulent conditions from arising in the cryogenic fluid as transferred, and the leakage path prevents structural instability in the inner sleeve itself that would result from a pressure imbalance across the sleeve - at typical operating pressures, the pressure differential that would result without such a leakage path would be likely to lead to collapse of the liner layer. The diameter reduction of the inner sleeve to form a compression fit with the inner diameter of the inner hose fixes the inner sleeve in position in the cryogenic hose, so that inner sleeve movement will not contribute to instability. 5 Further embodiments of the hose and the inner sleeve, of methods of manufacture of both hose and inner sleeve and of cryogenic fluid transfer, will be apparent to the skilled person in accordance with the invention as here defined.

Claims

1. A hose for fluid transfer, the hose comprising a tubular inner hose for fluid transport and an outer hose part, wherein the tubular inner hose has a corrugated inner surface defining a bore of the inner hose, the inner hose further comprising a tubular sleeve located within the bore of the inner hose, wherein an inner wall of the tubular sleeve is substantially smooth, wherein the tubular sleeve has a longitudinally extending slot and wherein an outer wall of the tubular sleeve forms a compression fit with the corrugated inner surface of the inner hose.

2. The hose of claim 1, wherein the longitudinally extending slot extends along the whole length of the tubular sleeve.

3. The hose of claim 2, wherein the tubular sleeve extends along substantially the whole bore of the inner hose.

4. The hose of any preceding claim, wherein the slot has a uniform width along the length of the tubular hose.

5. The hose of any preceding claim, wherein the slot has a width of 0.67 to 2 per cent of a circumference of the tubular sleeve.

6. The hose of any preceding claim, wherein the tubular sleeve is formed of a single polymer composite.

7. The hose of any preceding claim, wherein the tubular sleeve comprises polypropylene.

8. The hose of any preceding claim, wherein the tubular sleeve comprises polyetherimide.

9. The hose of any preceding claim, wherein the tubular sleeve comprises a carbon reinforcement.

10. The hose of any preceding claim, wherein the tubular sleeve is between 1 and 2 mm in thickness.

11. The hose of any preceding claim, wherein the tubular sleeve is formed with a diameter greater than the diameter of the bore of the inner hose, wherein the tubular sleeve is radially compressed for insertion into the inner hose, and wherein a restoring force to expand the tubular sleeve to its formed size provides a compression fit with the corrugated inner surface of the inner hose.

12. Hose for fluid transfer as claimed in any preceding claim, wherein the hose is adapted for flow of cryogenic fluids.

13. Hose for fluid transfer as claimed in claim 12, wherein the inner hose is wrapped in one or more layers of superinsulation.

14. Hose for fluid transfer as claimed in claim 12 or claim 13, wherein the tubular inner hose has both corrugated inner and outer surfaces, and wherein the tubular inner hose is located within an outer hose part bore, a corrugated inner surface of the outer hose part defining the outer hose part bore.

15. Hose for fluid transfer as claimed in claim 14, wherein the outer hose part bore is adapted to provide a vacuum space between the outer hose part and the inner hose.

16. Insulated superconducting cable comprising a hose for fluid transfer as claimed in any of claims 1 to 15, with a superconducting cable disposed within the inner permeable tubular sleeve such that the inner hose is adapted for a conveying a low temperature fluid in the bore of the inner hose for cooling the superconducting cable.

17. The use of a hose for fluid transfer as claimed in any of claims 1 to 15 for conveying a fluid having a temperature below -150°C.

18. A method of lining a hose for fluid transfer, the hose comprising a tubular inner hose for fluid transport and an outer hose part, wherein the tubular inner hose has a corrugated inner surface defining a bore of the inner hose, the method comprising:forming a longitudinal slot in a length of tubing having a diameter greater than a diameter of the bore of the inner hose;compressing the length of slotted tubing radially to pass into the bore of the inner hose; andpassing the length of slotted tubing into the bore of the inner hose to form a tubular sleeve as a liner for the bore of the inner hose, wherein an inner wall of the tubular sleeve is substantially smooth, wherein the tubular sleeve has a longitudinally extending slot and wherein an outer wall of the tubular sleeve forms a compression fit with the corrugated inner surface of the inner hose.

19. The method of claim 18, wherein compressing the length of slotted tubing radially comprises passing the length of slotted tubing through a forming cone.

20. The method of claim 18 or claim 19, wherein compressing the length of slotted tubing radially comprises compressing the length of slotted tubing to substantially the diameter of the bore of the inner hose, and passing the length of slotted tubing into the bore of the inner hose comprises moving the length of slotted tubing against friction with the corrugated inner surface.

21. The method of claim 18 or claim 19, wherein compressing the length of slotted tubing radially comprises compressing the length of slotted tubing to a new diameter less than the diameter of the bore of the inner hose, retaining the length of slotted tubing at the new diameter, passing the length of slotted tubing into the bore of the inner hose comprises moving the length of slotted tubing substantially without friction, and further comprising releasing the retaining of the length of slotted tubing at the new diameter when in a final position to provide the compression fit with the corrugated inner surface.

22. The method of any of claims 18 to 21, wherein the longitudinal slot is formed by cutting the length of tubing with one or more knives.

23. The method of any of claims 18 to 22, wherein the lining of the hose takes place in line with the manufacture of the hose.

24. The method of any of claims 18 to 23, wherein the longitudinally extending slot is formed along a whole length of the slotted tubing.

25. The method of any of claims 18 to 24, wherein the tubing is formed of a single polymer composite.

26. The method of any of claims 18 to 25, wherein the tubing has a diameter greater than the diameter of the bore of the inner hose, wherein a restoring force to expand the tubular sleeve to its formed size provides the compression fit with the corrugated inner surface of the inner hose.

27. The method of claim 26, wherein the diameter of the tubing is 1.02 to 1.06 times the diameter of the bore of the inner hose.

28. The method of any of claims 18 to 27, wherein the hose is adapted for flow of cryogenic fluids.

29. The method of claim 28, wherein the inner hose is wrapped in one or more layers of superinsulation.

30. The method of claim 28 or claim 29, wherein the tubular inner hose has both corrugated inner and outer surfaces, and wherein the tubular inner hose is located within an outer hose part bore, a corrugated inner surface of the outer hose part defining the outer hose part bore.

31. The method of claim 30, wherein the outer hose part bore is adapted to provide a vacuum space between the outer hose part and the inner hose.

32. A method of manufacturing an insulating hose for a superconducting cable, comprising manufacturing and lining a hose according to any of claims 28 to 31, and disposing a superconducting cable disposed within the inner permeable tubular 5 sleeve such that the inner hose is adapted for a conveying a low temperature fluid in the bore of the inner hose for cooling the superconducting cable.

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