Tool apparatus and related method for forming a vessel

Abstract

There is provided a tool apparatus for forming a mould for a vessel, a vessel mould, and a method for forming a vessel using composite material. The tool apparatus comprises a shaft; a rollable sheet couplable to the shaft and rollable into a cylinder; and a sleeve within which the shaft is rotatable. The vessel mould comprises a main body template; an end-boss at an end of the body template; an annular inlay, in contact with a portion of the boss; and a seal between the inlay and end-boss. The method of forming a vessel comprises: forming a cylinder by rolling a sheet; coupling a shaft to the sheet along its edge; coupling an end formation to each end of the cylinder, the end formations engaging with a sleeve in which the shaft is rotatably mounted, the external facing surface of the cylinder and end formations forming a vessel mould; applying composite material to form a vessel; once the composite has cured, rotating the shaft to wind the rollable sheet; and removing the sleeve complete with shaft and sheet.

Description

[0001] TOOL APPARATUS AND RELATED METHOD FOR FORMING A VESSEL

[0002] The present invention relates to tool apparatus for use in forming a mould for a vessel, a vessel mould, and a method for forming a vessel. In particular, the present invention concerns to tool apparatus for use in forming a fluid retaining vessel formed using composite material.

[0003] BACKGROUND

[0004] In this regard, current state-of-the-art fully wrapped composite vessels such as hydrogen tanks employ the use of an internal liner to contain the compressed gas and are either classified as type III vessels which have a metallic liner, or type IV vessels which have a non-metallic liner.

[0005] Type III vessels for hydrogen containment use seamless aluminium liners to limit hydrogen embrittlement and to minimise the weight of the liner when compared to a steel liner. A disadvantage of this approach is the poor structural compatibility between aluminium alloys and carbon fibre reinforced plastic (CFRP). CFRP using standard modulus fibres will be subjected to higher degrees of strain under load compared to what the aluminium can withstand, particularly when subjected to cyclic loading. This can be reduced to a certain degree by allowing the aluminium liner to plastically deform on the very first pressure cycle, a process known as autofrettage, thereby placing the aluminium in a state of compressive strain when the tank is not pressurised. This extends the range of strain the aluminium can withstand over a pressure cycle. However, the aluminium is still cycled beyond its fatigue limit resulting in a tank which is limited in lifespan compared to Type IV tanks. The other drawbacks of Type III vessels are their higher overall cost driven by the high cost of manufacturing the seamless aluminium liner, higher weight compared to non-metallic solutions and the risk of galvanic corrosion between the aluminium alloy liner and the carbon fibre.

[0006] Type IV vessels for hydrogen containment use a polymer liner, typically HDPE, due to its good toughness and relatively low gas permeability. Using a polymer liner is attractive due to its lower cost and lower weight compared to metallic liners. Polymer liners can also have a longer lifespan due to their superior corrosion and fatigue resistance. However, there are drawbacks, principally that the liner is not lossless, particularly with hydrogen gas. As well as the obvious disadvantage of losing hydrogen through the walls of the tank, as the gas permeates through the liner, it builds up between the liner and the CFRP overwrap causing delamination and inward buckling of the liner if the pressure in the tank is too low. This prohibits the tank from being fully emptied. In addition, the polymer liner can potentially complicate the vessel end-of-life recycling process by introducing a mix of polymer materials within the liner and composite matrix.

[0007] An objective of the present invention is as such to seek to alleviate issues with existing tanks and to provide a composite, liner-less vessel / tank.

[0008] SUMMARY OF THE INVENTION

[0009] According to a first aspect of the present invention, there is provided tool apparatus for use in forming a vessel mould, the apparatus comprising: - a shaft; a rollable sheet couplable to the shaft and rollable into a cylinder configuration; and a sleeve member within which the shaft is rotatable; wherein rotation of the shaft in a first direction winds the rollable sheet onto the shaft. In this regard, the tool apparatus affords a rollable sheet that can be formed into a cylinder which can be collapsed when wound onto the shaft.

[0010] Preferably, the sleeve member extends longitudinally along the length of the shaft, the sleeve member having a slot through which the rollable sheet can extend. The slot in the sleeve allows the rollable sheet to pass therethrough onto the shaft so that it can be confined within the sleeve as it is wound onto the shaft.

[0011] Optionally, an edge of the rollable sheet and the shaft are couplable by way of a plurality of inter-engaging cut-outs and projections.

[0012] Preferably, the rollable sheet is rollable to form a cylinder, one or more fastenings being provided at the overlapping faces of the rollable sheet to hold the rollable sheet in the cylindrical configuration. These fastenings can be readily formed in the material of the rollable sheet.

[0013] Optionally, the edge of the rollable sheet coupled to the shaft is a free edge of the sheet running longitudinally internal to the formed cylinder. In this regard, the fastenings can be provided in the rollable sheet to create an amount of overlap of rollable sheet to afford a workable free edge for coupling to the shaft. Preferably, the one or more fastenings prevent unrolling of the rollable sheet to thereby retain the cylindrical configuration but allow the overlapping faces of the rollable sheet to be unfastened as the rollable sheet is wound onto the shaft. In this way the fastenings are unidirectional allowing release only under forces applied when the shaft is rotated to wind the rollable sheet onto the shaft.

[0014] Optionally, rotating the shaft in the first direction winds the rollable sheet onto the shaft, the rollable sheet passing through the slot in the sleeve member.

[0015] Preferably, when in a cylindrical configuration, end formations are provided at respective ends of the formed cylinder to form an at least substantially closed vessel mould profile.

[0016] Optionally, the end formations each comprise a domed component engaging an end boss component coupled to the sleeve member. The end boss component may become part of the finished vessel. The end boss component may define an opening to the vessel.

[0017] There may be castellations between the rolled sheet and the domed component to prevent the rolled sheet from rotating relative to the domed components and end-boss components.

[0018] Preferably, the rollable sheet and sleeve member are configured such that the rollable sheet can be accommodated within the sleeve member when wound onto the shaft.

[0019] Preferably, each end formation comprises a ring-like inlay in contact with the end boss component. The inlays avoid the need for structurally bonding the end boss components within the formed vessel. Optionally, each inlay is formed from metal, preferably grade 5 titanium.

[0020] According to a second aspect of the present invention, there is provided a vessel mould apparatus comprising: a main body template; an end-boss component at an end of the main body template; an inlay, especially an annular inlay, in contact with a portion of the boss component; a seal between the inlay and said end-boss. A vessel may be made from the mould. Composite materials, for example include filament winding, automated fibre placement or a combination of methods may be applied to the mould, over the main body template and inlay.

[0021] The main body template may be removed after the vessel material has been layed thereon (usually after at consolidation / curing step). Normally, the end boss remains as part of the vessel.

[0022] An advantage of embodiments according to the second aspect of the invention is that the shear stresses between the composite material deposited on the inlay, is less than the shear stresses if the composite material was deposited on the end boss directly.

[0023] Oftentimes, there is an end boss at each end of the vessel. The described inlay arrangement of the second aspect of the invention may therefore also be provided in the same way at each end.

[0024] The inlay is preferably very thin, such as less than 1mm thick. It is preferably ring-shaped or annular.

[0025] Normally there is a groove defined in the / each end-boss to receive, at least in part, the o-ring seal.

[0026] The inlay is preferably metallic, such as titanium.

[0027] The end boss may define an opening to the formed vessel, especially for the second aspect of the invention.

[0028] The main body template may be a soluble template, a mechanically collapsible template, the tool apparatus according to the first aspect of the invention or any other suitable template.

[0029] According to a further aspect of the present invention, there is provided a vessel or vessel mould formed from the apparatus as set out in the statements above.

[0030] According to a further aspect of the present invention there is provided a method of forming a vessel, the method comprising the following steps: forming a cylinder by rolling a rollable sheet upon itself and inter-engaging overlapping faces of the rolled sheet; coupling a shaft to the rollable sheet along an edge of the rollable sheet; coupling an end formation to each end of the cylinder, the end formations engaging with a sleeve in which the shaft is rotatably mounted, the external facing surface of the cylinder and end formations forming a vessel mould; applying composite material to form a composite vessel over the vessel mould; once the composite material has cured or consolidated, rotating the shaft to wind the rollable sheet on to the shaft; and removing the sleeve complete with shaft and rollable sheet through one of the end formations. In this way, a vessel can be readily and economically formed using the vessel mould.

[0031] Preferably, a fluid barrier coating is applied over the vessel mould, the coating optionally being a hydrogen barrier coating. The fluid barrier coating allows the predominate use of composite materials without compromising the hermetic seal of the vessel.

[0032] Optionally, one or more fastenings are provided for holding the rolled rollable sheet in a cylindrical configuration, the fastenings being configured to allow unfastening of the overlapping faces of the rolled rollable sheet, when the shaft is rotated in a first direction to wind the rollable sheet onto the shaft.

[0033] The rolled sheet may be made of two parts, for example an outer cylinder and an inner overlapped portion. Each part is may therefore be rolled into a constant curve or radius.

[0034] Preferably, annular inlays are provided within each end formation, in contact with an end boss component. These avoid the requirement of structurally bonding the end boss components within the formed vessel.

[0035] Optionally, the end formations are movable inwardly of the formed vessel for access.

[0036] According to a further aspect of the present invention there is provided a vessel formed by the method defined above wherein optionally the end formations are movable inwardly of the formed vessel for access. It will be appreciated that providing a vessel without a liner not only reduces the weight of the vessel or tank directly through its removal, but also reduces the inside diameter of the composite, thereby reducing the hoop stress. This allows a reduction in the composite laminate thickness, further reducing weight.

[0037] The present invention hence provided a practical means of producing a low cost, recyclable, single or multiple use tool that can inwardly collapse and be extracted through an opening in the end boss, following the composite wrapping and curing process. A practical means of applying a lossless hydrogen barrier coating system as well as a novel end boss interface and sealing method are also encompassed by the invention. The processes for the fabrication and extraction of the tool, as well as the application of the hydrogen barrier coating, can be automated for high volume production.

[0038] The vessel formed from the apparatus and / or method described herein may be a composite cryogenic tank.

[0039] BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the inventions and together with the detailed description herein, serve to explain the principles of the inventions. It is emphasized that, in accordance with the standard practice in the industry, various features may or may not be drawn to scale. In fact, the dimensions of the various features may be arbitrarily increased or reduced for clarity of discussion. The drawings are only for purposes of illustrating embodiments of inventions of the disclosure and are not to be construed as limiting the inventions.

[0041] FIG. 1 (1.1 and 1.2) are perspective views illustrating a rollable sheet element of the present invention as rolled into a cylindrical configuration, with FIG 1.2 showing an enlarged view of a fastening;

[0042] FIG. 2 (2.1 and 2.2) are perspective views of shaft and slotted sheet components of the present invention, with FIG 2.2 showing an enlarged view of a slot in the sheet component;

[0043] FIG. 3.1 shows a cross-sectional view of a vessel mould;

[0044] FIGs. 3.2 -3.6 show enlarged views of elements of the end formations of the vessel mould; FIGs. 4.1-4.3 show perspective and cross-sectional views of vessel mould without end formations to illustrate connection of the rollable sheet to the shaft;

[0045] FIGs. 5 and 6 show perspective views of the vessel mould, and the formed composite vessel over the mould respectively;

[0046] FIGs. 7.1 and 7.2 show a cross-sectional views of the vessel, in particular the end formation;

[0047] FIG. 8 shows a perspective view of the finished vessel;

[0048] FIG. 9 shows further embodiment of the vessel forming process; and, FIG. 10 shows a perspective view of the finished vessel.

[0049] DETAILED DESCRIPTION

[0050] Referring to the drawings, like reference numerals are used to indicate like or analogous components throughout the several views.

[0051] As shown in FIGS.1.1 -1.2, there is illustrated a rollable sheet (1), over which the cylindrical portion of the composite tank is ultimately formed.

[0052] The sheet (1) is fabricated from thin (e.g. 1mm thick) sheet metal (e.g. 304 stainless steel). In this regard, the sheet flat pattern can be CNC waterjet or laser cut to include key-hole cutouts (2) and slotted cutouts (3).

[0053] The sheet (1) can be formed into a rolled configuration using, for example, a CNC roller bending machine. Tabs (4) can be spot welded to the sheet (1) following the bending process. The tabs (4) are arranged to engage into the slotted cutouts (3), whereby flap (5) which is formed by the slotted cutout (3) is snapped into position as shown, thereby locking the connection between the tab and cutout.

[0054] As shown in FIGS.2.1-2.2, there is illustrated a mandrel -like tool (6) for supporting the rollable sheet (1) during the manufacturing process (e.g. during the forming of the composite tank, typically by method of filament winding as discussed later).

[0055] The tool (6) comprises a sleeve-like casing (7) and a shaft (8). The tool (6) is moreover formed to include a slot feature (10). The shaft (8) is supported by bearings (11) near each end of the casing (7) (only one is shown in Figure 2.1) and can be driven to rotate about the casing’s longitudinal axis. The shaft (8) can be driven by manual or powered means. The shaft includes a number of projections or buttons (9) which can align and engage with the key-hole cutouts (2) in the sheet (1).

[0056] As shown in FIGS. 3.1-3.6, there is illustrated a pair of end-domes (12.1,12.2) connected to end-bosses (13.1, 13.2), over which the two end-domed portions of the composite tank are ultimately formed. The sheet (1) is sandwiched between the two end domes, over which a cylindrical portion of the tank is formed. This assembly is supported by the casing (7) by means of the contact between the outside diameter of the casing and the inside diameter of the end-bosses (i.e. D in FIG. 3.3). The end-bosses (13.1 , 13.2) are formed from high strength material, for example they are metallic, and form part of the finished vessel.

[0057] The end-bosses (13.1, 13.2) are threaded on the inside (14) for attaching tank piping, TPRDs, etc, or blanking off the opening. Moreover, the end bosses are threaded on the outside (15) for fitting of the end-boss retaining nut (25), shown in FIG. 8. For certain embodiments, the end-bosses have a groove (16) for fitting a hydrogen gas rated O-ring complete with back-up ring. The end-domes (12.1,12.2) can be formed from lightweight polymer and may be moulded or 3D printed. They can be attached to the end bosses (13.1, 13.2) by threaded fasteners. The sheet (1) is supported by a lip feature (17 in FIG.3.4) on each end dome.

[0058] Of note, the end-domes include at their edge a lip feature (17) which can flex inwards under a concentrated edge load when the sheet (1) is collapsed inwards for removal.

[0059] The slot (18 in FIG.3.2) cuts through the lip making it discontinuous. This slot allows the overlapped portion of the sheet (1) to pass through the lip feature (17) before the sheet is collapsed inwards for removal.

[0060] As shown in FIGS. 4.1-4.3, the inside free edge (19) of the sheet (1) posts through the slot (10) in the sleeve-like casing (7) and engages the shaft (8). The shaft is rotated until the buttons (9) on the shaft engage with the key-hole cutouts (2) in the sheet (1).

[0061] In this regard, following the forming of the composite tank around the mould formed by the sheet (1) and end formations (12.1, 12.2), the casing (7) is fixed from rotating, with the tank being free to rotate about the casing (7). The shaft (8) is driven to rotate, winding the sheet (1) around the shaft (8), pulling the sheet (1) inside the casing (7). During this process, the tabs (4) automatically release from the slotted cut-outs (3) on the sheet (1). In this connection, the tabs (4) release by virtue of the fact that the force applied by the rotating shaft acts with a radial inward component, the engagement configuration of the tabs and cut-outs permitting release on application of such a force.

[0062] The longitudinal seam (20 in FIG.1.1 and FIG. 5) along the sheet overlap can be filled to form a smooth profile. A filler material is applied, cured, and sanded smooth. The filler can be lightweight, epoxy or polyester based, and sandable. The filler can be cured by a UV lamp. The filler can be applied without removing the oxide layer on the sheet, so a strong bond is not achieved. Mould release is applied to the entire outside surface of the assembly, including the sheet, end-domes, and end-bosses.

[0063] A pair of annular inlays (21.1 - see FIGS. 3.5-3.6) are formed from thin sheet metal. The sheet metal is cut to form a flat ring. Each inlay is formed into a shallow dish to match the profile of its respective end-boss (13.1, 13.2). Each inlay can be made from grade 5 titanium. The inlay can be formed from material which is sub mm thick. The inlay is prepared for structural bonding on its outside (convex) surface. This preparation may be anodising followed by the application of a bonding primer. The inlays are placed in contact with the end-bosses (13.1, 13.2). By virtue of their large surface area and low weight, they are held in position by the tackiness of the mould release. Alternatively, a thin layer of non-curing, wax like material is used to aid the temporary attachment of the inlays. As a result of forming and curing of the composite vessel, the inlays are inlaid and bonded to the inside surface of the composite tank. As such, they prevent uncured composite material entering the seal or gasket groove and form a sealing surface for the o-ring seals or whatever type of seals / gaskets which may be used.

[0064] The inlays (21.1) avoid the need for structurally bonding the end-bosses (13.1, 13.2) to the main composite tank. Such a bonded interface would be difficult to achieve due to excessive shear stress in the bond. The inlays (21.1), on the other hand, have a small cross section area relative to the bond surface area due to their fabrication from thin sheet metal. This results in a shear stress at the bonded joint which can be resisted by the structural adhesive. Moreover, the use of high strength titanium alloys is not prohibited by cost due to the low use of sheet metal and the absence of machining. The use of titanium alloys can provide a high strength to stiffness ratio (springiness) which allows the inlay to resist the high degrees of strain associated with Carbon Fiber-Reinforced Polymers (CFRPs) with standard modulus fibres. A hydrogen barrier coating may be applied to all the surfaces prepared with mould release. If a hydrogen barrier coating is applied, it may serve as a structural adhesive, in which case, it is also applied over the inlays (21.1). Indeed, in accordance with the second aspect of the invention, the inlays can be used with other templates for the vessel, such as a dissolvable template, instead of the rollable sheet apparatus described in the above embodiment.

[0065] As shown in FIGS. 5-6, the composite tank (28, FIG. 6) is formed over the assembly (FIG. 5). The composite materials may for example include a thermoset or thermoplastic matrix. The composite materials may inherently form a barrier to the hydrogen gas or may not contain the hydrogen gas. The process of laying up the composite materials may for example include filament winding, automated fibre placement or a combination of methods. The consolidation / curing process may include all known methods. A separate curing process may be eliminated all-together by method of in-situ consolidation or by any other means.

[0066] Following the forming of the composite tank, the sheet (1) can be collapsed inwards and can be extracted through an opening in one of the two end-bosses (13.1, 13.2).

[0067] As shown in FIGS. 7.1-7.2, the end-bosses (13) together with end-domes (12) are pushed slightly inwards of the tank. This can be done since they were prepared with mould release. This allows access for the fitting of hydrogen rated O-rings and back-up rings (22) into the groove (16) in the end-boss. This can allow the replacement of the O-rings and back-up rings during the service life of the tank; however, it is expected that the O-rings and back-up rings will have a working life to match that of the tank. Following the fitting of the O-rings and back-up rings, the end-bosses are pulled back into position. As shown in FIG 8, the endboss retaining nuts (25) are fitted by threading onto the end-boss external thread and tightened to the required torque. This pulls each end-boss firmly into contact with the inlay, thereby squeezing the O-rings. A composite tank 28 is thus formed, having an opening 29 for access for fluid storage during use.

[0068] As shown in Fig. 9, for certain embodiments, the end-domes (12) may be detached from the end-bosses and pushed inwards of the tank 38, as described, leaving the end-bosses (13) in place. A cutter (not shown) may then be inserted into the tank 38, and the end-domes (12) cut into pieces small enough to be removed from the opening 29.

[0069] It will be understood that the various aspects of the present invention can be practiced alone or in combination with one or more of the other aspects, as will be appreciated by those skilled in the relevant arts. The various aspects of the invention can optionally be provided in combination with one or more of the optional features of the other aspects of the invention. Also, optional features described in relation to one aspect can typically be combined alone or together with other features in different aspects of the invention. Any subject matter described in this specification can be combined with any other subject matter in the specification to form a novel combination.

[0070] Various aspects of the invention are described in detail with reference to the accompanying figures. Still other aspects, features, and advantages of the present invention are readily apparent from the entire description thereof, including the figures, which illustrates a number of exemplary aspects and implementations. The invention is also capable of other and different examples and aspects, and its several details can be modified in various respects, all without departing from the scope of the present invention. Accordingly, each example herein should be understood to have broad application, and is meant to illustrate one possible way of carrying out the invention, without intending to suggest that the scope of this disclosure, including the claims, is limited to that example. Furthermore, the terminology and phraseology used herein is solely used for descriptive purposes and should not be construed as limiting in scope. In particular, unless otherwise stated, dimensions and numerical values included herein are presented as examples illustrating one possible aspect of the claimed subject matter, without limiting the disclosure to the particular dimensions or values recited. All numerical values in this disclosure are understood as being modified by "about". All singular forms of elements, or any other components described herein are understood to include plural forms thereof and vice versa.

[0071] Language such as "including", "comprising", "having", "containing", or "involving" and variations thereof, is intended to be broad and encompass the subject matter listed thereafter, equivalents, and additional subject matter not recited, and is not intended to exclude other additives, components, integers or steps. Likewise, the term "comprising" is considered synonymous with the terms "including" or "containing" for applicable legal purposes. Thus, throughout the specification and claims unless the context requires otherwise, the word “comprise” or variations thereof such as “comprises” or “comprising” will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers.

[0072] Any discussion of documents, acts, materials, devices, articles and the like is included in the specification solely for the purpose of providing a context for the present invention. It is not suggested or represented that any or all of these matters formed part of the prior art base or were common general knowledge in the field relevant to the present invention. In this disclosure, whenever a composition, an element or a group of elements is preceded with the transitional phrase "comprising", it is understood that we also contemplate the same composition, element or group of elements with transitional phrases "consisting essentially of’, "consisting", "selected from the group of consisting of’, “including”, or "is" preceding the recitation of the composition, element or group of elements and vice versa. In this disclosure, the words “typically” or “optionally” are to be understood as being intended to indicate optional or non-essential features of the invention which are present in certain examples but which can be omitted in others without departing from the scope of the invention.

[0073] References to directional and positional descriptions such as upper and lower and directions e.g. “up”, “down” etc. are to be interpreted by a skilled reader in the context of the examples described to refer to the orientation of features shown in the drawings and are not to be interpreted as limiting the invention to the literal interpretation of the term, but instead should be as understood by the skilled addressee.

[0074] Whilst the present invention has been described in relation to a tank or vessel for containing fluids, it will be understood that the tank or vessel may be utilised in other appropriate environments.

Claims

CLAIMS1 . Tool apparatus for use in forming a vessel mould, the apparatus comprising:- a shaft; a rollable sheet couplable to the shaft and rollable into a cylinder configuration; and a sleeve member within which the shaft is rotatable; wherein rotation of the shaft in a first direction winds the rollable sheet onto the shaft.

2. Tool apparatus as claimed in claim 1 , where the sleeve member extends longitudinally along the length of the shaft, the sleeve member having a slot through which the rollable sheet can extend.

3. Tool apparatus as claimed in claim 1 or 2, wherein an edge of the rollable sheet and the shaft are couplable by way of a plurality of inter-engaging cut-outs and projections.

4. Tool apparatus as claimed in any one of claims 1 to 3, wherein the rollable sheet is rollable to form a cylinder, one or more fastenings being provided at the overlapping faces of the rollable sheet to hold the rollable sheet in a cylindrical configuration.

5. Tool apparatus as claimed in claim 4, wherein the edge of the rollable sheet coupled to the shaft is a free edge of the sheet running longitudinally internal to the formed cylinder.

6. Tool apparatus as claimed in claim 4 or 5, wherein the one or more fastenings prevent unrolling of the rollable sheet to retain the cylindrical configuration, but allow the overlapping faces of the rollable sheet to be unfastened as the rollable sheet is wound onto the shaft.

7. Tool apparatus as claimed in any preceding claim, wherein rotating the shaft in the first direction winds the rollable sheet onto the shaft, the rollable sheet passing through the slot in the sleeve member.

8. Tool apparatus as claimed in any preceding claim, wherein when in a cylindrical configuration, end formations are provided at respective ends of the formed cylinder to form an at least substantially closed vessel mould profile.

9. Tool apparatus as claimed in claim 8, wherein the end formations each comprise a domed component engaging an end boss component coupled to the sleeve member.

10. Tool apparatus as claimed in claim 9, wherein each end formation comprises a ring-like inlay in contact with the end boss component.11 . Tool apparatus as claimed in claim 10, wherein each inlay is formed from metal and optionally grade 5 titanium.

12. Tool apparatus as claimed in any preceding claim, wherein the rollable sheet and sleeve member are configured such that the rollable sheet can be accommodated within the sleeve member when wound onto the shaft.

13. A vessel mould formed from the apparatus as claimed in any preceding claim.

14. A method of forming a vessel, the method comprising the following steps: forming a cylinder by rolling a rollable sheet upon itself and inter-engaging overlapping faces of the rolled sheet; coupling a shaft to the rollable sheet along an edge of the rollable sheet; coupling an end formation to each end of the cylinder, the end formations engaging with a sleeve in which the shaft is rotatably mounted, the external facing surface of the cylinder and end formations forming a vessel mould; applying composite material to form a composite vessel over the vessel mould; once the composite material has cured or consolidated, rotating the shaft to wind the rollable sheet on to the shaft; and removing the sleeve complete with shaft and rollable sheet through one of the end formations.

15. A method as claimed in claim 14, wherein a fluid barrier coating is applied over the vessel mould, the coating optionally being a hydrogen barrier coating.

16. A method as claimed in claim 14 or 15, wherein one or more fastenings are provided for holding the rolled rollable sheet in a cylindrical configuration, the fastenings being configured to allow unfastening of the overlapping faces of the rolled rollable sheet, when the shaft is rotated in a first direction to wind the rollable sheet onto the shaft.

17. A method as claimed in any one of claims 14 to 16, wherein annular inlays are provided within each end formation, in contact with an end boss component.

18. A method as claimed in any one of claims 14 to 17, wherein the end formations are movable inwardly of the formed vessel for access.

19. A vessel formed by the method of any one of claims 14 to 18.

20. A vessel as claimed in claim 19, wherein the end formations are movable inwardly of the formed vessel for access.

21. A vessel mould apparatus comprising: a main body template; an end-boss component at an end of the main body template; an inlay, especially an annular inlay, in contact with a portion of the boss component; a seal between the inlay and said end-boss.

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