The invention also relates to a vessel for containing a fluid under pressure, comprising such a jacket, and a process of manufacturing a jacket, as well as a process of manufacturing a vessel.

TECHNICAL BACKGROUND Such a jacket and such a vessel are known from DE-A-195 06 124, which document describes an oil drum, the gables of which are to be welded on the inside of the drum, but the welding operation is to be performed from the outside of the jacket.

Such a welding method is complicated and may result in low precision regarding the weld seam, and therefore requires high demands regarding the tolerances of the measurements of the gable. This contributes to high manufacturing costs.

Furthermore, the described jacket is provided with a support edge, which has a very small transverse extension. If, during manufacture, the gable becomes too small or warped, it will pass the support edge and fall into the interior of the oil drum. Thus, high demands in tolerances of the measurements of the gable and the support edge are required to avoid this. Furthermore, if the whole support surface, i. e. the circle formed by the edge of the gable, is not allowed to bear against the support edge of the jacket simultaneously, the gable may also in this case pass the support edge and fall into the oil drum. Consequently, a very exact assembly method is required.

FR-A-2 304 022 describes a pressure vessel for a gas, generally called a bottled gas cylinder. During use, a burner is connected to the bottled gas cylinder. By means of a valve, the amount of gas that is to be let out of the cylinder is adjusted, i. e. the gas flame can in this way be adjusted.

During manufacture of the bottled gas cylinder described therein, an annular depres- sion is formed on the outside of a bell-shaped body. The annular depression forms on the inside of the bell-shaped body a protrusion, which forms a stop for a closure member. The closure member is a dome-shaped disc with a peripheral rearwardly folded annular wall, which extends in a direction away from the continued spherical extension of the dome. The annular wall of the closure member is adapted to bear against the inner wall of the dome-shaped body from the protrusion all the way to the end surface. Thereafter they are welded or soldered together.

Such a design requires a great deal of accuracy during manufacture as regards the dimensions of the parts, since the annular cylindrical wall of the closure member is to be pressed until it bears against the inner, cylindrical wall of the bell-shaped body along its whole surface. This requires in turn special tools for allowing the fitting to be performed. Furthermore, there is a risk of crevice corrosion at the welded or soldered joint.

GB-A-191 796 describes a lamp of the acetylene gas kind for a bicycle. A tube for storing acetylene gas is arranged on the frame of the bicycle. A tubing or a hose supplies acetylene gas to the lamp.

The tube is provided with an annular depression, which forms a stop member on the inside of the tube. A closure member is soldered against the respective stop member. The soldering is performed in such a way that there is a risk of crevice

corrosion. Furthermore, the solderings shown herein cannot resist any larger stress, but can only be seen as sealing seams.

During manufacture of a pressure vessel it is also common that a circular-cylindrical jacket is provided with dome-shaped ends, which are welded edge-to-edge with the respective end edges of the cylinder. This requires great precision during manufac- ture of dome and jacket, since the edges must bear against each other about the whole circumference of the end edge of the jacket. If the periphery of the dome, i. e. the circumferential edge is larger than the end edge of the jacket, a part of all of the end edge of the jacket will bear against the inside of the dome instead of against the circumferential edge of the dome. If, on the contrary, the circumferential edge of the dome is smaller than the end edge of the jacket, the circumferential edge of the dome will not reach the end edge of the jacket about all of the end edge of the dome.

Jackets having a small thickness of material often take a non-circular-cylindrical form, for which reason adjustment of the dome against the jacket before connection, by means of e. g. welding, will become more difficult.

OBJECT OF THE INVENTION The object of the present invention is to provide a semi-finished product of a vessel, i. e. a jacket and a finished vessel for a fluid under pressure, which are simpler and cheaper to manufacture.

SUMMARY OF THE INVENTION This has been achieved by a jacket as initially defined, which is characterised in that the end portion forms a portion, at least partially diverging towards the end surface in a direction along the central axis and in a direction from said central portion, against which portion a closure member is intended to be unreleasably connected.

The object has also been achieved by a vessel of the initially defined kind, comprising such a jacket and a closure member mounted at said at least partially diverging portion.

The object has also been achieved by a process of manufacturing such a jacket a, including providing a rectangular sheet of metal or plastic having a substantially rectangular form, profiling of said at least partially diverging portion of at least one of the end portions for achieving a desired form thereof, by applying at least one profiling tool to the inside of the jacket and at least one profiling tool to the outside of the jacket, wherein at least one of the profiling tools is actively brought to rotate.

The object has also been achieved by a process of manufacturing such a vessel, including placing of the closure member against said at least partially diverging portion, and connection of the closure member and said diverging portion.

Hereby, a jacket and a vessel, respectively, have been achieved, the manufacture and assembly of which does not require high precision, and can therefore be automated, which in turn contributes to low manufacturing costs. Further there is provided a jacket and a vessel, respectively, with a support, on which one can put the semi-finished or finished product. A further advantage is that reduced thickness of material can be used than what is the case at a vessel or a jacket according to previously known technology for the corresponding working pressure.

Suitably, the end portion comprises a guiding member. Hereby is achieved guiding of the closure member before its connection.

Preferably, the inner side of the jacket at the level of the end portion is provided with at least one stop member about its inner circumference. Hereby is prevented that the closure member as a whole or partially passes the end portion, for example by obliqueness.

Suitably, the end portion is provided with a boundary area between said stop member and guiding member. Hereby is achieved an ideal portion for placing and connection of the closure member.

Preferably, the stop member comprises at least one projection. In particular, its outer side is provided with at least one depression about its exterior circumference forming said projection. Hereby is achieved stiffening of the jacket.

Of course, the projection can also be achieved by welding of a number of protru- sions, a ring or the like, depending on the form of the jacket. This, however, results in more sub-operations during manufacture.

Suitably, the projection is directed substantially towards the central axis.

Preferably, the divergence of the guiding member is substantially constant. Hereby is achieved an edge about the circumference of the jacket, against which the closure member can slide such that it can take a suitable centred position.

Suitably, the divergence of the guiding member has an angle a between 5° and 60° relative to the central axis. Preferably, the divergence of the guiding member has an angle between 10° and 45° relative to the central axis. It is, however, advantageous that the angle a is between 20° and 27°. Even more advantageous the angle is 23°.

Hereby is achieved an end portion which provides ready handling during mounting of the closure member.

Preferably, the jacket is symmetric about said central axis. In particular, the jacket is substantially circular-cylindrical. Said stop member is in this case suitably annular- shaped. Of course, the jacket may have another cross section than circular, for example square or some other polygon form.

Advantageously, said boundary portion forms a circle. Furthermore, said stop member is annular.

Suitably, the at least partially diverging portion has a part, which is closest to the central axis.

Preferably, the stop member has at least partially a diameter, which is larger than the principal diameter of the jacket. Suitably, the guiding member has at least partially a diameter which is larger than the principal diameter of the jacket. Hereby is achieved a broader support, when the jacket is placed vertically, e. g. on a floor.

Alternatively, the stop member has at least partially a diameter, which is smaller than the principal diameter of the jacket. Suitably, said guiding member has at least partially a diameter which is smaller than the principal diameter of the jacket.

Hereby is achieved a jacket, which can readily be built into a shell.

Preferably, the closure member is dome-shaped. Hereby is achieved a form which is suitable for a pressure vessel. The closure member is thus convex and has a circumferential edge, whereby the circumferential edge meets said diverging portion in a substantially parallel relation. The form of the closure member allows the use of a thinner material. When using thicker material, preparation of the joint, i. e. preparation of a wedge-formed (diverging) opening towards the exterior of the vessel, may be necessary for achieving an excellent weld joint.

Preferably, the closure member is connected to the jacket by a weld joint directly applied to the periphery of the closure member, where it bears against the inside of the jacket. Hereby, a simple, reliable and non-expensive welding method for the vessel is achieved.

Preferably, the jacket and/or the closure member are provided with at least one opening intended for mounting of means for heating or cooling of a fluid contained in the vessel, and/or for conveying fluids to or from the vessel. Hereby is achieved a possibility of preparing the container for several alternative fields of use.

More precisely, said means for heating a fluid contained therein comprises a thermal means, such as an electric immersion heater, an oil burner, a gas burner or a tube coil for heating or cooling. Alternatively, or in addition, said means for heating or cooling of a fluid contained in the vessel, comprises control equipment, such as a thermostat or a shunt.

Advantageously, the process of manufacturing a jacket includes profiling of said substantially diverging portion of at least one of the end portions by applying at least one profiling tool to the inside of the jacket and at least one profiling tool to the outside of the jacket, wherein at least one of the profiling tools is actively brought to rotate.

Suitably, the process includes bending a rectangular sheet of metal or plastic to a substantially circular-cylindrical shape with a longitudinal slit, which is welded together, whereby said bending and welding precede the provision of said substantially diverging portion.

Advantageously, the process of manufacturing a vessel includes placing the closure member against said substantially diverging portion, and connecting the closure member and said diverging portion.

Suitably, the connection is performed by welding of the side of the closure member which faces the end portion.

During manufacture of jacket, gables and/or complete vessels in other materials than sheet metal, completely different methods of forming of the end portion may be used, including moulding, thermal forming etc. Connection of the parts may then be performed by means of accessible methods for the respective material, by using e. g. glue or thermoset plastics.

DRAWING SUMMARY In the following, the invention will be described in detail by reference to annexed drawings, in which Figure la is an exploded view of a pressure vessel with a jacket and two closure members, Figure lb is a partial cut out with a cross section of the end portion and the closure member of the pressure vessel, Figure 2 illustrates the placing of the closure member before connection, Figure 3 illustrates the jacket with the closure member welded thereon.

Figs. 4a-4h illustrate alternative cross-sections of the end portion, Figure 5 illustrates a profiling device for profiling of end portions, Figure 6 illustrates a profiling tool of the profiling device shown in Figure 5.

Figure 7 illustrates an alternative embodiment of the vessel, and.

Figure 8 illustrates the vessel with auxiliary equipment mounted thereon.

DETAILED DESCRIPTION Fig. la is an exploded view of a pressure vessel 1, comprising a jacket 2, which has been manufactured by bending of a thin (about 2 mm) rectangular sheet of steel, aluminium or the like, by means of a bending roller until the two opposite edges bear against each other. The sheet obtains by this procedure a substantially circular- cylindrical form. In order to maintain this form and to create a continuous jacket, the opposite edges are welded together. The circular-cylindrical form is substantially symmetric about a central axis A.

Alternatively, a suitable polymer material, such as thermoset plastics, is formed to the desired form.

Closure member 3 in the form of a gable or a bottom is dome-shaped for reception of a pressure of a fluid, i. e. a gas or a liquid, contained in the vessel. Such closure members are also called"dome-shaped gables". Each closure member 3 has been made, for example, by pressing or pressure-turning of a circular sheet with a circular edge 4. Of course, the closure member may also be made of a suitable polymer material.

The partial cut out according to Fig. lb is a cross section of a part of the dome and an end portion 5 of the jacket. The end portion 5 comprises a stop member 6 in the form of a depression 6a, which corresponds to a projection 6b on the other side of the sheet, i. e. the inside of the jacket 2. A cross-section of the depression 6a as well as of the projection 6b is at least partially substantially U-shaped and has a point 6c, which lies closest to the central axis A, i. e. where the jacket has its smallest radius.

The portion between the central part of the jacket 2 and the point 6c is denoted by 6d. The end portion 5 also comprises a guiding member 7, which extends towards the opening from the stop member 6. The portion between the point 6c and the

guiding member 7 is denoted by 6e. A cross section of the guiding member 7 is straight or rectilinear. A boundary portion, in the form of a discontinuity, where the U-shaped stop member 6 is transformed to the rectilinear form of the guiding member, has been denoted by 8.

The end portion 5 comprises a diverging portion 8a including the part of the projection 6b, defined by the point 6c and the guiding member 7. The diverging portion thus diverges from the point 6c towards the opening and to an end surface 5a, in the form of a circle, which defines an opening 5b. More precisely, the guiding member 7 has an angle a towards the central line A, i. e. towards the surface of the jacket, which is smaller than the angle of the stop member 6, where the U-formed stop member is transformed to a straight, i. e. rectilinear form, via the boundary portion 8. This angle may be between 5° and 60° but practical tests have shown that an angle between 10° and 45° results in a better precision during mounting, and that an angle between 20° and 27° is more advantageous for fitting of the closure member 3 during mounting. The best result was achieved at the angle 23°.

It should be noted that the lateral extension of the end surface 5a may be very small.

It may be so small, that it forms an edge, in the case of a circle, the edge is an annular line.

Since the jacket 2 is circular-cylindrical, the end portion 5 is annular, which in turn means that the guiding member 7 and the stop member 6-i. e. the depression 6a and the projection 6b-are annular. In a corresponding way, the point 6c as well as the boundary portion 8 constitute a cross section of an annular line.

Profiling of the end portion 5 stabilises the jacket, which means that it can better take its circular-cylindrical form.

Below the end portion, along the central axis A, there is a central portion 9, and on the other side of the central portion 9, still in the direction of the central axis A, there is a further end portion, which is mirror-inverted to the former end portion.

Also this end portion 5 has an end surface Sa, which defines an opening 5b.

The jacket 2 and the gables 3 are further provided with openings 10, which are intended for receiving temperature-affecting means, such as heating or cooling coils, thermostat, shunt, feed and return lines for fluids etc.

In practical tests, the diameter of the jacket has varied between 500 mm and 1600 mm, while the length has varied between 500 mm and 2000 mm, but of course the invention is not limited to these dimensions.

Fig. 2 shows how the gable 3 is placed with its edge 4 against the end portion 5 at the boundary portion 8. This is the ideal relationship, i. e. when the manufacture has resulted in a dome 3 of a desired size. If the dome or the jacket during manufacture obtains a size which does not correspond to the respective ideal size, the gable or dome 3 will bear with its edge 4 along the stop member 6, i. e. on the projection 6b down to the portion 6c, or along the guiding member 7 up to the end surface 5 a.

Hereby is achieved low demands regarding tolerances during manufacture of the gables 3 and the jacket 2. This will make the manufacture less expensive at the same time as an automation will be easier to perform.

When the jacket 2 is placed with the axis A in a vertical position, the gable 3 is lifted in place at the end portion of the jacket. For this purpose, no large precision is required, but the guiding member 7 is self-adjusting against the boundary portion 8, since the shape of the guiding member 7 will result in that the gable or dome 3 strives for taking a position substantially perpendicular to the central axis A of the jacket. For this purpose, an force is applied in the axial direction of the cylinder.

Simultaneously, the jacket 2 is stabilised and takes a substantially circular-

cylindrical form, owing to the circular edge 4 of the dome, which bears against the boundary portion 8. If the dome 3 would be warped, it will be pressed about the whole periphery and will simultaneously be aligned, such that an even contact is achieved, and undesired slits between the gable 3 and the end portion 5 will be avoided. When mounting the gable 3 onto the opposite side, the jacket is first turned, such that said opposite side is directed upwards.

Alternatively, the jacket 2 is placed with the central axis A directed horizontally, i. e. with the two end portions 5 on each side of a vertical plane. In this case, the two closure members or gables 3 are simultaneously applied from the respective direc- tion. When they are pressed against the respective boundary portion 8, the form of the jacket is at the same time adjusted such that it becomes substantially circular- cylindrical and undesired slits between the gable and the jacket are minimised. Such simultaneous applying of the gables 3 is of course applicable with the central axis directed in another direction desired for mounting, whereby a suitable fixture for the jacket is used.

If the diameter of the circular edge 4 of the gable 3 does not correspond to the diameter 8 of the boundary portion, the edge 4 will bear against the stop member 6 or against the guiding member 7, depending on whether the diameter of the edge 4 is too small or too large.

Owing to the form of the stop member 6, the gable 3 does not risk to slide inside the inner portion 6c and owing to the form of the guiding member 7, a gable 3, disregarding whether the edge 4 has too large or too small a diameter (of course within certain limits), can be fitted in such a way that it can be fixed to the stop member 6 or to the guiding member 7.

Thus, the manufacture of the jacket 2 and the closure member 3 does not require any high precision.

Fig. 3 shows together with two partial enlargements how the gable 3 has been connected to the jacket 2 by a weld joint 11, which has been directly. where the edge 4 of the dome-shaped closure member 3 meets the diverging portion 8a in a substantially parallel relation (cf. the partial cut out), however, with a small slit (not to be mixed up with the above mentioned undesired slits). This results during welding in an excellent burning-through and material combination och in a complete filling of the slit. Hereby is also crevice corrosion avoided, at the same time as the underlying continuously diminishing diameter of the diverging portion 8a counter-acts that the melted or fluid material penetrates into the vessel 1 during the connection operation.

In this context it should be indicated that it is not necessary before welding of the gable to connect it to the jacket by spot-welding. Hereby a welding operator or a welding robot instantaneously will be able to perform a continuous weld joint along the whole joint between the gable 3 and the jacket 2. Owing to the fact that the spot welds are no longer necessary, a better weld joint is also achieved.

Of course, connection of the closure members 3 and the jacket 2 is not limited to welding, but could of course be performed by soldering, gluing or sealing of joints by thermosetting polymers, etc., depending on the material chosen for the vessel.

Please note that the closure member 3 may be made of another material than the jacket 2.

Hereby the whole process can be easily automated by use of conventional conveying, holding, and welding machines or other connection machines.

When the closure member 3 has been attached to the jacket, is also achieved stiffening and securing of the substantially circular-cylindrical form of the jacket obtained during fitting.

Please also note that when manufacturing at least the jacket in a polymer material, it is possible to directly achieve the desired profile of the end portions by means of for example blow-moulding or dye-casting of the whole jacket 2. What has been said about continuous weld joint is of course suitable also for these materials, however, adapted to the connection method used.

Fig. 4a shows a first alternative cross section of the end portion 5, which only includes the diverging end portion 8a according to Fig. 1, i. e. which does not include the portion 6d described in Fig. 1, and which is inside the portion 6c. The continuation of the jacket 2 has been indicated by broken lines. According to this embodiment the end portion 5 has a larger diameter than the rest of the jacket 2.

Fig. 4b shows a second alternative cross section of the end portion 5, where the diverging portion 8a includes a substantially arched portion 6b, and a further arched portion 7, which has a bending opposite to the bending of the portion 6e. This implies that the angle between the portion 7 and the central axis A is reduced in the direction towards the end surface 5a.

Fig. 4c shows a third alternative cross section of the end portion 5, where the diverging portion 8a solely consists of a guiding member 7, which-depending on the angle of the guiding member in relation to the central axis-also constitutes a stop member. The larger the angle a, the better the guiding member acts as stop member, but at the same time its guiding ability is reduced. In this embodiment, the end surface 5a is in line with the circular-cylindrical portion of the jacket 2. Since there is no boundary portion 8, a is in this case defined as the angle between the guiding member 7 and the central axis A at the point 6c.

Fig. 4d shows a fourth alternative cross section of the end portion 5. In this case the jacket 2 has been provided with an endportion 5, which functions in the same way

as in Fig. 4c, but the end portion 5 of which has a larger diameter than the circular- cylindrical portion of the jacket 2. Also in this case, a is defined as the angle between the guiding member 7 and the central axis A at the point 6c.

Fig. 4e shows a fifth alternative cross section of the end portion 5, where the guiding member 7, outside the diverging portion 8a, is provided with an annular portion 12, which is parallel to and is in line with the circular-cylindrical portion of the jacket 2. The portion 12 facilitates vertical placing of the vessel 1 on a floor or placing of other equipment on top of the vessel.

Fig. 4f shows a variant of the end portion 5 according to Fig. 4a, in which the diverging portion 8a is arched and has a diameter which is larger than the main part of the jacket 2.

Fig. 4g shows a variant of the end portion 5 according to Fig. 4a. In this case the guiding member 7 has been provided with an annular portion, in a way correspond- ing to what is described in connection with Fig. 4c.

Fig. 4h shows a variant of the end portion 5 according to Fig. lb. In this case the cross section is rounded and has substantially the form of a V.

In this connection it should be added that the stop member 6 does not have to be formed in the sheet but could as well be welded thereon, in the form of a plurality of protrusions or a ring, on the inside of the sheet. Thus, it would be possible to provide the end portions shown in Figs. 1 and 4a-4h with such a stop member 6.

The same applies to the guiding member 7.

The angle a has in the Figs. 4a-4h a value in accordance with what has been described in connection with Fig. lb.

Of course, the different shapes of the portions 6e and/or 7 shown in Figs. 1 and 4a-4h may be combined in a suitable way. This also includes the portion 12 shown in Figs. 4e and 4g. Furthermore, the point 6c may of course be flattened out and thereby achieve another form than a point, e. g. a surface.

Fig. 5 shows schematically how the jacket 2 is placed on two support rollers 20,21 and a pair of opposite rotatable profiling tools in the form of a male member 22 and a female member 23, which has the form that gives the desired cross section of the shaped end portion 5, cf. Figs. lb and 4a-4h above. A driving means 24 drives the male member 22 and/or the female member 23.

Instead of tools profiled for the angled shape of the end portion, more than two rotatable tools profiled in another way may be used.

Fig. 6 shows schematically the male member 22 and the female member 23 with driving means 24 having driving axles 25,26 and power transmission in the form of cog wheels 27,28.

Profiling of the stop member 6 and the guiding member 7 is performed by applying the male member 22 and the female member 23 with suitable mechanisms against the outside and the inside, respectively, of the jacket 2. The driving means 24 drives the tools 22,23 in the opposite direction, causing the jacket 2 to rotate. The support rollers 20,21 have no driving of their own but are brought to rotate when the jacket 2 is caused to be rotated by the tools, and rolls the jacket 2 a suitable number of turns, whereby the desired profile of the end portion 5 is achieved.

Profiling of the opposite side of the jacket 2 is preferably performed at the same time as another pair of tools 22,23 are placed on suitable mechanisms at the opposite end of the rollers 20,21.

The jacket 2 is before the profiling not guaranteed a circular-cylindrical form, since the sheet is thin. Profiling achieves stiffening of the cylinder and improves the geometry of the jacket.

Fig. 7 shows a second embodiment of the vessel 1, the jacket 2 of which having an integrated gable and is made in one piece, e. g. by deep-drawing, and with only one end portion 5, i. e. with only one opening 5b. In this case, only this end portion 5 is profiled for reception of a dome-shaped closure member 3. This achieves vessel 1 suitable for storing for example liquefied petroleum gas or for use as a water heater.

A suitable profile of the end portion 5 can be chosen according to anyone of the alternatives presented above.

Fig. 8 shows a so-called accumulator tank 30 comprising a vessel 1 according to the invention, for heating of water by an electric immersion heater 31 or a tube coil 32 leading to a not shown sun panel or another producer of hot or cold fluid. The accumulator tank may of course be connected to a wood or oil boiler. The over- pressure is 1-10 bars in the accumulator tank, which has connections 33, 34, for connection to radiators. A shunt 35 is provided for regulation of the flow to the radiators.

The accumulator tank 30 is moreover provided with a water heater 36 comprising a vessel 1 according to Fig. 7 for heating of tap water. The overpressure in this vessel is normally 5-10 bars or more. Of course, the water heater 36 may alternatively comprise a vessel 1 according to Fig. 3 or a vessel of another kind.