This invention relates to a seal arrangement, and in particular to a seal arrangement whereby a tubular component of metallic form can be connected in a gas tight, sealed manner to a composite material, tubular component.

A number of applications exist in which it is desired to sealingly connect a composite material tubular component to a metallic material tubular component to allow the passage of fluids along a flow passage defined, at least in part, by the tubular metallic material component and the tubular composite material component. Where an assembly of this type is subject to temperature variations, then the differential thermal expansion that can occur when such changes in temperature take place can result in seals formed between the components leaking which, obviously, is undesirable. Variations in the applied pressures can also impact upon the seal quality. Such leakage issues can be especially problematic where significant temperature changes are experienced, for example in devices which, when operating, are at extremely low, cryogenic temperatures but which, when out of use, for example to allow servicing or maintenance operations to be performed, are allowed to increase to room temperature. It is an object of the invention, therefore, to provide a seal arrangement suitable for use in such applications and in which at least some of the disadvantages associated with known arrangements are overcome or are of reduced effect.

According to an aspect of the invention, therefore, there is provided a seal arrangement comprising a first tubular component, an annular recess formed in a surface of the first component, an O-ring located within the annular recess, the O-ring engaging a surface of a second tubular component, a passage formed in one of the first and second components and opening into the annular recess, and a resin material element located within the annular recess, the resin material deforming the O-ring to pressurise the O-ring into engagement with the first and second components, forming a seal therebetween. By pressurising the O-ring in this manner, a good seal can be formed between the first and second components which is able to be maintained even in the event of differential thermal expansion occurring therebetween or in the event of significant variations in applied pressures. The passage is preferably provided in the first component. A plurality of such passages may be provided, if desired, assisting in ensuring that the annular recess is completely filled with the resin material.

Preferably a pair of O-rings are located within the annular recess. Conveniently, the passage opens into a part of the annular recess between the O-rings.

An end part of the second component is conveniently received within an end part of the first component. However, this need not always be the case and the reverse is also possible. The second component is conveniently of a metallic material, and the first component is preferably of a composite material such as a fibre reinforced plastics material. However, arrangements are possible in which the structure is reversed such that the annular recess is formed in the metallic material component. A collar may be provided, the collar engaging the end part of the first component to prevent or resist radial expansion thereof. Such an arrangement is advantageous as the sealing forces which could otherwise result in radial expansion of the first component can be reacted to the collar. Furthermore, the collar may aid in maintaining the sealing engagement during cooling of the assembly.

The resin material conveniently takes the form of an adhesive material, and preferably incorporates a quantity of a ceramic or other material filler. The presence of the filler may reduce shrinkage of the resin material upon cooling or curing, aiding in ensuring that the deformation and prestressing of the O-ring is maintained.

A second, similar sealing arrangement may be provided at the opposite end of the first component, sealing the first component to a third component. Such an arrangement may be used to, for example, form an electrically insulating break within a metallic material tube. According to another aspect of the invention there is provided a method for forming a seal arrangement comprising providing a first tubular component, an annular recess being formed in a surface of the first component, an O-ring being located within the annular recess, the O-ring engaging a surface of a second tubular component, and a passage being formed in one of the first and second components and opening into the annular recess, and supplying a resin material to the annular recess via the passage, the resin material deforming the O-ring to pressurise the O-ring into engagement with the first and second components, forming a seal therebetween, and curing or allowing the resin material to cure.

The method may incorporate a number of the features recite hereinbefore.

According to a further aspect of the invention there is provided a seal arrangement comprising a first tubular component, a second tubular component, an end part of which is located within an end part of the first component, and a collar engaging the end part of the first component to prevent or resist radial expansion thereof, applying a radially inwardly directed load thereto, in use.

As set out hereinbefore the first component may be provided with an annular recess within which a resin material is located, under pressure, the collar resisting radial expansion of the first component as a result of the presence of the resin material under pressure.

Alternatively, between the first and second components may be located a liner element in the form of a tubular member, the collar applying a compressive load to the liner element to urge the liner element into sealing engagement with the second component.

The liner element may take the form of an ultra high molecular weight polyethylene material or the like. Such an arrangement is advantageous as the sealing forces which could otherwise result in radial expansion of the first component can be reacted to the collar. In an arrangement of this type, a resin filled annular recess as described hereinbefore may be provided in the liner element or in the second component, the resin being supplied under pressure as described hereinbefore to aid prestressing of an O-ring located within the annular recess. The invention will further be described, by way of example, with reference to the accompanying drawings, in which:

Figure 1 is a diagrammatic representation of a seal arrangement in accordance with an embodiment of the invention;

Figure 2 is an enlarged view illustrating part of the arrangement of Figure 1; Figure 3 is a view similar to Figure 1 illustrating a variant; Figure 4 is a view similar to Figure 1 illustrating an alternative embodiment; and Figure 5 is a view similar to Figure 4 illustrating a variant.

Referring to Figures 1 and 2, a seal arrangement 10 is illustrated whereby a seal is formed between a first tubular component 12 of composite material form, for example of wound fibre reinforced resin material, and a second tubular component 14 of metallic, for example steel, form. By way of example, the first component 12 may be of glass fibre reinforced plastics material form. As illustrated, an end part of the second component 14 is received within the end part of the first component 12, the dimensions of the first and second components 12, 14 being such that the second component is a close fit within the first component 12. If required, machining of the first and second components 12, 14 may be undertaken to achieve the desired fit.

The inner surface of the first component 12 is shaped to define an annular recess 16. The profile of the recess 16 is such that it includes, adjacent opposite axial ends thereof, relatively deep parts 16a separated by a shallower central part 16b. A pair of O-rings 18 are located within the annular recess 16, each being located within a respective one of the relatively deep parts 16a. Radial passages 20 extend through the wall of the first component 12, interconnecting the central part 16b with the exterior of the first component 12. An annular collar 24 of metallic construction encircles an end part of the second component 14, defining a space between a wall of the collar 24 and the outer surface of the second component 14 of radial thickness sufficient that the end part of the first component 12 can be received therein. Passages 26 are formed in the collar 24 which align with the passages 20. The collar 24 is conveniently an interference fit with the second component 14, but this need not always be the case.

During assembly, the end part of the second component 14 is introduced into the end part of the first component 12, the O-rings 18 carried by the first component 12 bearing against the outer periphery of the second component 14. With the O-rings 18 present, the fit of the second component 14 within the first component 12 is an interference fit, and so the O-rings 18 are deformed or prestressed in this condition. The collar 24 is fitted around the end part of the second component 14, the end of the first component 12 being received between the second component 14 and the collar 24. The presence of the collar 24 serves to resist radial expansion of the first component 12. A resin material is supplied to the annular recess 16 via the passages 20, through the passages 26 provided in the collar 24, the resin material being supplied under pressure such that the resin material serves to further resiliently deform the O-rings 18, forcing the O-rings 18 into intimate, sealing contact with the first and second components 12, 14, thus sealing the first and second components 12, 14 to one another. By way of example, the resin material may be introduced at a pressure in the region of 50bar. The sealing force resulting from the presence of the O-rings 18 and the resin material is reacted, at least in part, to the collar 24, avoiding significant radial expansion of the first component 12. Where the pressure with which the resin material is supplied is relatively low then the collar 24 may not be required. However, in many applications it is thought that they will preferably be provided. In addition, the resin material bonds to the first and/or second components 12, 14.

Another benefit of the presence of the collar 24 is that, upon cooling of the assembly and associated differential thermal expansion/contraction of the parts of the arrangement, the collar 24 will aiding in ensuring that sealing contact is maintained between the O-rings 18 and the second component 14. The resin material conveniently takes the form of an adhesive material which, preferably, contains a quantity of a ceramic or other suitable material filler. The presence of the filler is advantageous in that shrinkage of the resin material during cooling or curing is reduced, aiding in maintaining the stressing of the O-rings 18, and thus in the formation of a good, leak resistant assembly.

After introduction of the resin material, the material is cured or allowed to cure, whilst still under pressure, and hence with the O-rings 18 maintained in their resiliently deformed condition, forming a solid resin material element 28 located within the annular recess 16. It will be appreciated that the seal arrangement described hereinbefore is advantageous in that, if used in applications in which differential thermal expansion of the first and second components 12, 14 occurs, the pressurisation and resilient deformation of the O-rings 18 allows the O-rings 18 to continue to maintain a good seal between the first and second components 12, 14. Even if the resin material element 28 were to soften, its presence within the annular recess 16 will ensure that pressurisation and the associated resilient deformation of the O-rings 18 will be maintained, and so the seal between the components will be maintained in a functioning condition.

As illustrated, an opposite end of the first component 12 is sealed to a third component 30 in a similar manner to that described hereinbefore. The seal arrangement of the invention thus allows a composite material component to be incorporated part way along the length of a metallic material tube. This may be advantageous in that it may allow weight reductions to be made, reduced quantities of metallic materials being used. Furthermore, an electrically insulating break may be formed part way along the length of the metallic material tube. The seal arrangement is able to withstand wide fluctuations in temperature whilst maintaining a good quality seal between the components. By way of example it may be used in cryogenic applications in which extremely low temperatures are experienced, but in which the arrangement may periodically be brought to room temperature, for example to allow servicing or maintenance operations to be performed. The sealing quality is sufficiently good that the escape of helium or other gasses through the seal arrangement can be avoided.

The materials and designs of the first and second components 12, 14 are conveniently selected such that, at around room temperature, the first and second components 12, 14 are of matched or substantially matched coefficients of thermal expansion in the axial direction of the arrangement so that minimal shear loads are experienced by the bond between the resin material and the first and/or second components 12, 14.

Although as described hereinbefore the annular recess 16 is formed in the first component 12, as shown in Figure 3 embodiments are also possible in which the recess 16 is formed in the second component 14. In such an arrangement, the resin material supplied to the recess 16 bears against a resin rich surface of the first component, assisting in the formation of a leak resistant structure.

If desired, annular recesses 16 could be formed in both the first component 12 and the second component 14.

Figure 4 illustrates an alternative embodiment of the invention, and like reference numerals are used where appropriate to denote like parts. In the arrangement of Figure 3, a liner element 32 of tubular form is located at the inner periphery of the first component 12, the liner element 32 being disposed, in use, between the first and second components 12, 14. The collar 24 applies a radially inwardly directed load to the collar 24, compressing the liner element 32 against the first and second components 12, 14, forming a gas tight seal therebetween.

Whilst the liner element 32 may be of a range of materials, one suitable material takes the form of an ultra high molecular weight polyethylene or the like material.

In order to achieve a good bond between the liner element 32 and the first component 12, suitable coatings may need to be applied to one or other or both of the engaging surfaces of the first component 12 and the liner element 32.

As with the arrangements of Figures 1 to 3, the arrangement of Figure 4 is advantageous in that an electrically insulating break may be incorporated into a metallic tube, the seal arrangement being such that gases are retained within and unable to escape from the tube. The seal arrangement is sufficiently robust that it is able to withstand variations in the applied pressure, and to accommodate movements as a result of differential thermal expansion.

As shown in Figure 5, the arrangement of Figure 4 may be modified in line with the arrangements of Figures 1 to 3 to include annular recesses 16 containing O-rings 18, a resin material being supplied under pressure to the recess 16 to resiliently deform the O-rings 18. The arrangement may thus enjoy the benefits of the embodiments of Figures 1 to 3.

It will be appreciated that the seal arrangements described hereinbefore represents just a few embodiments of the invention and that a wide range of modifications or alterations may be made thereto without departing from the scope of the invention as defined by the appended claims.