GB2363439A - End fitting for a hose - Google Patents

Abstract

An end fitting 200 for sealing an end of a hose (10, fig 1) comprising a tubular body (12, fig 1) of flexible material arranged between inner and outer helically wound wires (22, 24, fig 1) comprises an inner member 202 disposed partially within the hose, and a sealing ring adapted to seal at least part of the tubular body between the sealing ring and the inner member. The sealing ring comprises a sealing member 204 and a compression member 206 for compressing the sealing ring into a sealing engagement with tubular body of the hose. The compression member is tightenable against the sealing member in order to selecitvely increase or decrease the compression force it exerts. Preferably the sealing ring is made of PTFE, and the compression member is made of stainless steel. The hose may be used at a variety of temperatures, from above 100{C, to below -200{C.

Description

2363439 END FITTING H"ING IMPROVED SEALING CAPABILITIES This invention

relates to an end fitting having improved sealing capabilities, and more particularly relates to an end fitting for a hose. The invention also relates to a 5 hose, per se, and to a method of making a hose. The invention particularly relates to hose intended for use 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

10 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 15 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 20 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 25 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 30 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.

007654OA1. 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.

This type of hose is usually formed by the following technique: an inner wire is 5 wrapped around a tubular mandrel to form an inner coil; an inner reinforcing layer is wrapped around the tubular mandrel and the inner coil; a sealing layer is wrapped around the inner reinforcing layer; an outer reinforcing layer is wrapped around the sealing layer; an outer wire is wrapped around the outer reinforcing layer to form an outer coil; the ends of the hose are secured by crimping; and the hose is removed from 10 the mandrel. In particular, the crimping creates an unrecoverable plastic deformation in the components of the ends of the hose.

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

According to one aspect of the invention there is provided an end fiffing for 15 sealing an end of a hose comprising a tubular body of flexible material arranged between inner and outer helically wound wires, characterised in that the end fitting comprises: an inner member adapted to be disposed at least partially within the hose; and a sealing ring adapted to sea[ at least part of the tubular body between the sealing ring and the inner member; wherein the sealing member comprises a sealing ring and 20 a compression member for compressing the sealing ring into sealing engagement with said part of the tubular body.

In one especially advantageous embodiment, the compression member is tightenable against the sealing member in order to selectively increase or decrease the compression force of the compression member against the sealing member In another especially advantageous embodiment, the compression member and the sealing ring are removably securable to the hose.

Thus, in accordance with the present invention there is no unrecoverable plastic deformation in the components of the end fitting.

Preferably, the compression member is adapted to compress the sealing ring equally in all directions.

Preferably, the compression member is of adjustable diameter, and further comprises a tightening means which can apply a force to reduce the diameter of the compression member, thereby compressing the sealing ring within the compression member. We prefer that the compression member comprises a split ring or a jubilee clip.

In a particularly preferred embodiment, the compression member is made of a 5 material which contracts less than the sealing ring when subjected to cooling. This provides an advantageous way of making the hose, as described below. The sealing ring and the compression member may be any suitable material. There are a number of materials which have the desired difference in contraction under cooling. We prefer that the compression member is stainless steel and the sealing ring is 10 polytetrafluoroethylene (PTFE). More preferably, the sealing ring comprises reinforced PTFE, such as glass filled PTFE, as this helps to prevent creep. The sealing ring preferably comprises 10 to 20 wt% of the glass filling.

It is preferred that the inner member is made of a material which contracts less than the sealing ring when subjected to cooling. This feature has the effect that when 15 the end fitting is cooled, the sealing ring contracts more than the inner member, thereby tightening the grip of the sealing ring on the inner member, and improving the seal. The inner member may be made of any suitable material. Stainless steel has been found to be particularly suitable.

Preferably the outer surface of the inner member is provided with at least one 20 formation thereon which is adapted to engage said part of the tubular member, below the sealing ring. The or each formation stretches the film, which acts to improve the seal of the tubular member and to make it more difficult for the tubular member to be pulled from between the inner member and the sealing ring; the stretching makes a more even and smoother film surface under the seal. It is preferred that the or each 25 formation comprises a projection extending circurnferentially around the outer surface of the inner member, Desirably, there are two or three of said formations.

It is preferred that the sealing ring is an interference fit with the inner member.

In a preferred embodiment, the end fitting further comprises a load transferring means adapted to transfer axial loads applied to the hose around the sealing member 30 in order to reduce the axial load on the hose between the sealing member and the inner member.

The load transferring means preferably comprises a hose engaging member, a load transmitting member and an end member secured to the inner member. The arrangement is such that the sealing member is disposed between the load transmitting member and the end member, and that the hose engaging member and the end member are connected through the load transmitting member.

5 The hose engaging member is adapted to engage the hose in such a manner that at least part of the axial forces within the hose are transferred from the hose to the hose engaging member. The hose engaging member transfers these forces to the load transferring member, and the load transferring member transfers these forces to the end member. In this way, at least part of the axial forces in the hose bypass the sealing 10 member, thereby improving the reliability of the seal provided by the sealing member.

It is preferred that the inner member and the load transferring means include a portion configured to receive the wires of the hose. The inner member can be provided with helical recesses adapted to receive the inner wire therein, and the load transferring means can be provided with helical recesses adapted to receive the outer wire therein.

15 Preferably, it is the hose engaging member of the load transferring means which is provided with the helical recesses.

The load transferring member preferably comprises a load transferring plate, which is typically disk shaped, having an aperture adapted to receive the hose therethrough; plate has a surface engageable with the hose engaging member, 20 whereby loads can be transferred from the hose engaging member to the plate. The load transferring member preferably further includes a load transferring rod secured between the plate and the end member for transferring loads from the plate to the end member. A tightening member, such as a nut, can be provided on the rod.

The inner member preferably has a hose end which is adapted to extend within 25 an end portion of the hose, and a tail end remote from the hose end. The end member is arranged on one side of the sealing member, adjacent the tail end, and the hose engaging member is arranged on the other side of the sealing member adjacent the hose end.

According to another aspect of the invention there is provided a hose comprising 30 a tubular body of flexible material arranged between an inner and an outer helically wound wire, the tubular body serving to transport fluid through the hose and to prevent fluid leakage through the body, characterised in that the hose further comprises an end fitting as described above.

The hose engaging member may transfer loads from the hose simply by virtue of the frictional forces between the hose and the hose engaging member. However, it is preferred that the hose engaging member is adapted to secure a part of the hose 5 which is folded back over an outer part of the hose engaging member. This arrangement makes it possible for the folded part of the hose to transmit loads to the hose engaging member. The folded part of the hose may be part of the tubular body, but it is preferably an axial strengthening means in the form of a braid, as described below.

10 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, 15 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 20 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.

25 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.

The materials of construction of the hose 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 30 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.

In the preferred embodiment each reinforcing layer comprises a fabric, most 5 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 10 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).

15 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.

20 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 25 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 greaterthan 50%, more usually greater than 30 70%. A crystallinity up to 85-90% is possible.

UHIVIWPE is described in, for example, US-A-4344908, US-A-4411845, USA4422993, US-A-4430383, US-A-4436689, EP-A-183285, EP-A-0438831, and EP-A0215507.

It is particularly advantageous that the or each reinforcing layer comprises a highly oriented UHMWPE, such as that available from DSM High Performance Fibres BV (a Netherlands company) under the trade name DYNEEMA, or that available from 5 the US corporation AlliedSignal Inc. under the trade name SPECTRA.

Additional details about DYNEEMA are disclosed in a trade brochure entitled "DYNEEMA; the top performance in fibers; properties and application" issued by DSM High Performance Fibers BV, edition 02/98. Additional details about SPECTRA are disclosed in a trade brochure entitled "Spectra Performance Materials" issued by 10 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 15 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.

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 20 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 25 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 30 film. Preferably there would be at 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 5 provided.

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

Preferably, the hose further comprises an axial strengthening means adapted to reduce deformation of the tubular body when the tubular body is subjected to axial 10 tension, More preferably, the axial strengthening means is further adapted to exert a radially inward force on at least part of the tubular body when axial strengthening means is subjected to axial tension.

By means of this arrangement, the axial strengthening means improves the ability of the hose to cope with axial stresses, and at the same time can contribute to 15 the structural integrity of the hose during axial tensioning by pressing against at least part of the tubular body.

Preferably the axial strengthening means comprises a generally tubular member formed of a sheet of material provided in a tubular shape, such that the tubular member can maintain the integrity of its tubular shape when subjected to axial tension. The hose 20 may be provided with two or more tubular members in order to further improve the performance of the hose under axial tension.

In a particularly advantageous embodiment the axial strengthening means is provided in the form of a generally tubular braid. In this specification the term "braid" refers to a material which is formed of two or more fibres or yarns which have been

25 intertwined to form an elongated structure. It is a feature of braid that it can elongate when subjected to an axial tension. It is a further feature of braid that, when provided in a tubular form, its diameter will reduce when the braid is subjected to axial tension. Thus 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 part of the tubular 30 body when subjected to axial tension.

The axial strengthening means is described in more detail in our copending United Kingdom patent application of even date entitled "Hose Having Improved Axial Strength."

The axial strengthening means may also be formed of the same material as the or each reinforcing layer.

The helices of inner and outer wires are typically arranged such that they are 5 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.

10 When the hose is intended for cryogenic applications, then it is desirable to provide insulation over the tubular body. The insulation could be provided between the outer wire and the tubular member andlor outside the outer wire. The insulation may comprise material conventionally used to provided insulation in cryogenic equipment, such as a synthetic foam material. One suitable form of insulation is described in our 15 copending United Kingdom patent application of even date entitled "Hose Having Improved Flexing Capabilities". This application also describes a way of improving the flexing capabilities of the hose, and this improvement may be used in the present invention.

It is preferred that the axial strengthening means is also provided around the 20 insulating layer to compress the insulation layers and maintain their structural integrity. The axial strengthening means around the insulation layer is preferably provided in addition to the axial strengthening means between the outer gripping member and the tubular body.

The hose according to the invention can be provided for use in a wide variety of 25 conditions, such as temperatures above 1 OOOC, temperatures from VC to 1000C and temperatures below OOC. With a suitable choice of material, the hose can be used at temperatures below -200C, below -50'C or even below - 1 OOOC. 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 30 liquid oxygen (bp -1183"C) or liquid nitrogen (bp -1960C), in which case the hose may need to operate at temperatures of -20WC 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 5 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 10 materials, such as strong acids, 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 15 order to provide a tubular body formed of the sheet material; (c) wrapping a wire around the tubular body to form an outer coil; and (d) removing the hose from the mandrel; characterised by the following steps:

(e) disposing an inner member in an open end of the hose; 20 (f) applying a sealing ring over an outer surface of the tubular body; and (g) applying a compression member over the sealing ring, and compressing the sealing member into sealing engagement with the tubular member and the inner member using the compression member.

Preferably, the compression member is made from a material which contracts 25 less than the sealing ring when subjected to cooling. Preferably also, the compression member includes a means for adjusting the compressive force applied to the sealing ring; a split ring is particularly suitable for use as the compression member. This arrangement makes possible a particularly preferred manufacturing process.

In this process, the compression member is applied to the sealing ring and 30 tightened, then the compression member and sealing ring are subjected to at least one cooling cycle. This causes the sealing member to contract relative to the compression member, whereby the compressive force applied by the compression member is reduced. While the cooling is maintained, the compressive force applied by the compression member is then readjusted to bring it back to approximately the same level as before the cooling, and then the temperature is increased. This cycle may be applied as many times as desired. It is preferred that the cooling cycle is applied at least two 5 or three times and that each time the end fitting is cooled to temperatures at least 50C below the intended operating temperature of the hose. This technique has three important benefits.

First, if the hose is operated at temperature above the cooling temperature, then the sealing ring will receive additional compression from the compression member by 10 virtue of the thermal expansion of the sealing member which will take place after the cooling is removed.

Second, the hose will have substantial seal energisation at temperatures at least as low as the cooling temperature. This is particularly useful when the hose is to be used in cryogenic applications. Thus, the temperature to which the hose is cooled is 15 preferably as low as the temperature to which the hose will be subjected in the use for which it is intended. In general, we preferthat the cooling temperature is -500C or less, more preferably-1 OO'C or less, and still more preferably -1 500C or less. Preferably, the cooling is carried out with liquid nitrogen, whereby the cooling temperature can be as low as about -1 96'C.

20 Third, the possibility of creep failure is much reduced, or even eliminated, by utilising the hydrostatic stress provided by the compression member.

We prefer that the inner member is made of a material which contracts less than the sealing ring when subjected to cooling. This has the effect that cooling the end fitting causes the sealing ring to grip the inner member more tightly, thereby improving 25 the sealing of the end fitting when the hose is operated at low temperatures.

Preferably the coils and the sheet material are applied under tension in order to provide the hose with good structural integrity.

Preferably the sheet material in step (b) comprises two reinforcing layers sandwiching a sealing layer, as described above. In the preferred embodiment, an inner 30 reinforcing layer, in sheet form, is wrapped helically around the inner coil and the mandrel; then the sealing layer, in sheet form, is wrapped helically around the inner reinforcing layer; then the outer reinforcing layer, in sheet form, is wrapped around the sealing layer. Usually a plurality of sealing layers would be applied.

Preferably the inner and outer coils are applied in a helical configuration having the same pitch, and the position of the coils of the outer coil are positioned half a pitch length offset from the position of the coils of the inner coil.

5 It is possible for the hose to be removed from the mandrel before the end fitting is disposed within it. Alternatively, the end fitting can be disposed within the rest of the hose by sliding the inner mandrel therealong up to an end of the hose, then securing the rest of the hose to the end fitting while the end fitting and the rest of the hose remain on the mandrel.

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

Reference is now made to the accompanying drawings, in which:

Figure 1 is a schematic cross-sectional view of a hose according to the invention, with the end fitting omitted; and Figure 2 is a schematic cross sectional view of an end fitting for a hose, according to the invention.

In Figure 1 a hose is generally designated 10. In order to improve the clarity the winding of the various layers in Figure 1 has not been shown. The hose 10 comprises a tubular bo - dy 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. A generally 20 tubular member 20, which provides axial strengthening, is disposed around the outer surface of the outer reinforcing layer 16. The tubular body 12 and the tubular member 20 are 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 25 corresponding to half the pitch length of the helix of the coils.

An insulation layer 26 is disposed around the outer wire 24. The insulation layer may be a conventional insulating material, such as a plastics foam, or may be a material described in our copending United Kingdom patent application entitled "Hose Having Improved Flexing Capabilities".

The tubular member 20 is formed of two sets of fibres which are braided to form a tubular braid. This is described in greater detail in our copencling 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 5 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 tubular axial strengthening member 20 is drawn over the outside of the outer reinforcing layer 16. The outer wire 24 is then 10 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 1, where the pitch length 15 is designated p. The insulation layer 26 may then be applied around the outer wire 24 and the tubular member 20.

The ends of the hose 10 are then sealed using the end fitting 200 shown in Figure 2. In Figure 2, the hose 10 has not been shown, in order to improve the clarity. The end fitting 200 comprises a substantially cylindrical tubular inner member 202 20 having a hose end 202a and a tail end 202b. The end fitting 200 further includes a sealing member which comprises a PTFE sealing ring 204 and a stainless steel split ring 206 around the PTFE sealing ring 204.

The end fitting 200 further includes a load transferring means comprises a hose engaging member 208, a load transferring member 210 and an end member in the form 25 of a disk-shaped plate 212. The load transferring member comprises a disk-shaped plate 214 and at least one load transferring rod 216. In figure 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 have apertures 212a and 214a respectively for receiving the rods 216.

The plates 212 and 214 may each be a Simonplate, 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 apertures 212b, and the tail end 202b of iiner member 202 is provided with apertures 202-c. Fixing bolts 220 extend through,e apertures 202b and 212b to secure the plate 212 to the tail end 202a of the inner member 202. 1 n Figure 2, there are two fixing bolts 220 and associated apertures, but it will be appreciated that fewer, or more, fixing bolts 220 and associated apertures 5 could be provided.

The hose engaging member 208 is provided with an inner helical recess in the form of grooves 208a which are adapted to receive the outer wire 24 of the hose 10 therein. The inner member 202 is provided with an outer helical recess in the form of grooves 202d which are adapted to receive the inner wire 22 therein. It will be seen 10 from Figure 2 that, like the inner and outer wires 22 and 24, the grooves 208a and 202d are spaced by half a pitch length p.

The inner member 202 is provided with two circumferential projections 202e which are located under the sealing ring 204. The projections 202e serve the improve the sealing of the tubular member 20 between the inner member 202 and the sealing 15 ring 204, and help to prevent the tubular member from inadvertently being pulled out of position.

The hose 10 is secured 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 wire 22 is received in the grooves 202d and the outer wire 24 is received in 20 the grooves 208a. The inner and outer wires 22 and 24 are cut back so that they do not extend along the inner member 202 beyond the grooves 202d and 208a. The insulation 26 is also cut back to this point. The inner reinforcing layer 14 is also cut back at this point, or at some point before the inner reinforcing layer 14 reaches the sealing ring 204. This means that the sealing layer 18 directly engages the outer surface of the 25 inner member 202. The rest of the tubular body 12, however, is allowed to extend along the inner member 202 between the inner member 202 and the sealing ring 204.

The hose engaging member 208 is then tightened to cause it to clamp down on the hose 10 bring it into firm engagement with the hose 10. The nuts 218 are then tightened, which induces some axial tension in the hose 10, thereby taking up any play 30 in the system. These forces are transmitted from 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 pulled back over the upper surface of the hose engaging member 208, and is secured to projections 208b extending from the upper surface of the hose engaging member 208.

The tubular body 12 extends underthe sealing ring 204. Afterthe hose engaging member 208 and the nuts 218 have been tightened, the split ring 206 is tightened in 5 order to increase the force applied on the tubular body 12 by the sealing ring 204.

The end fitting 200 is then cooled to a low temperature by liquid nitrogen. This causes the sealing ring 204 to contract relatively more than the split ring 206, whereby the compressive force applied on the sealing ring 204 by the split ring 206 is reduced. While the split ring 206 and the sealing ring 204 are at a relatively low temperature, the 10 split ring 206 is again tightened. The temperature is then allowed to rise to ambient conditions, whereby the compressive force on the sealing ring increases by virtue of the greater expansion of sealing ring 204 relative to the split ring 206.

This completes the end fitting for the hose 10. The hose engaging member 208 provides some sealing of the end of the hose 208, and helps to take axial forces in the 15 hose 10 around the sealing ring 204. The sealing ring 204 provides the remainder of the sealing of the hose 10.

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

Claims (23)

CLAIMS:

1. An end fitting for sealing an end of a hose comprising a tubular body of flexible material arranged between inner and outer helically wound wires, characterised in that 5 the end fitting comprises: an.inner member adapted to be disposed at least partially within the hose; and a sealing ring adapted to seal at least part of the tubular body between the sealing ring and the inner member; wherein the sealing member comprises a sealing ring and a compression member for compressing the sealing ring into sealing engagement with said part of the tubular body, and the compression member is 10 tightenable against the sealing member in order to selectively increase or decrease the compression force of the compression member against the sealing member

2. An end fitting according to claim 1, wherein the compression member and the sealing ring are removably securable to the hose.

3. A hose according to claim 1 or 2, wherein the compression member is adapted to compress the sealing ring equally in all directions

4. A hose according to claim 1, 2 or 3, wherein the compression member includes 20 a tightening means for adjusting the compressive force applied by the compression member to the sealing ring.

5. A hose according to claim 4, wherein the compression member is of adjustable diameter, and wherein the tightening means can apply a force to reduce the diameter 25 of the compression member, thereby compressing the sealing ring within the compression member.

6. A hose according to any preceding claim, wherein the compression member comprises a split ring or a jubilee clip.

7. A hose according to any preceding claim, wherein the compression member is made from a material which contracts less than the sealing ring when subjected to -17cooling.

8. A hose according to any preceding claim, wherein the compression member is stainless steel and the sealing ring is polytetrafluoroethylene.

9. A hose according to any preceding claim, wherein the outer surface of the inner member is provided with at least one formation thereon which is adapted to engage said part of the tubular member, underneath the sealing ring.

10 10. A hose according to any preceding claim, wherein the sealing ring is an interference fit with the inner member.

11. A hose comprising a tubular body of flexible material arranged between an inner and an outer helically wound wire, the tubular body serving to transport fluid through the 15 hose and to prevent fluid leakage through the body, characterised in that the hose further comprises an end fitting according to any preceding claim fitted to an end thereof.

12. A hose according to claim 8, wherein the tubular body comprises at least one reinforcing layer and at least one sealing layer.

13. 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 25 order to provide a tubular body formed of the sheet material; (c) wrapping a wire around the tubular body to form an outer coil; and (d) removing the hose from the mandrel; characterised by the following steps:

(e) disposing an inner member in an open end of the hose; 30 (f) applying a sealing ring over an outer surface of the tubular body; and (g) applying a compression member over the sealing ring, and compressing the sealing member into sealing engagement with the tubular member -18and the inner member using the compression member.

14. A method according to claim 13, wherein the compression member is made of material which contracts less than the sealing ring when subjected to cooling.

15. A method according to claim 13 or 14, wherein the compression member includes a tightening means for adjusting the compressive force applied to the sealing ring.

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16. A method according to claim 14 and 15, further comprising the following step after step (g):

(h) cooling the compression member and sealing ring to reduce the compressive force applied to the sealing ring by the compression member, then increasing the compressive force applied to the sealing 15 ring by the compression member by adjusting the tightening means.

17. A method according to claim 16, wherein in step (h) the compression member and the sealing ring are cooled to -100 "C or less.

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18. A method according to claim 16 or 17, wherein the compression member and sealing ring are cooled to by liquid nitrogen.

19. A method according to any one of claims 13 to 18, wherein the inner member is made of a material which contracts less than the sealing ring, when subjected to cooling.

20. A method according to claim 16, 17,18 or 19, wherein the inner member is also cooled with the compression member and the sealing ring.

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21. An end fitting for a hose substantially as herein described with reference to and as shown in the Figure 2.

22. A hose substantially as herein described with reference to and as shown in the accompanying drawings.

23. A method of making a hose substantially as herein described with reference to 5 and as shown in the accompanying drawings.