The present invention concerns a metal sleeve coupling and joints comprising a metal sleeve coupling. The joints are between ventilation ducts and/or accessories. In a special embodi- ment the joint is between heat resisting elongated ventilation ducts or heat resisting ventilation duct connector pieces and standard ventilation ducts or standard accessories, wherein the heat resisting ducts/connectors are capable of resisting high temperatures for a long period of time. There are classifications for the possibility of withstanding high temperatures for ducts. The ducts transfer flue gas and must withstand temperatures between 900 and 1000 degrees Celsius for at least half an hour or at least an hour to fulfil a European classification EN1366 according to EI30/60. This will give people time to evacuate a burning building. According to this classification the cross section must be intact, and the outside temperature of the duct must not exceed 140 degrees Celsius in average and not over 180 degrees Celsius in one point.

At the moment, according to prior art, steel ducts are arranged in buildings, which thereafter are provided with mineral wool to insulate the ducts. The mineral wool is usually at- tached by means of chicken wire around the ducts and mineral wool. Joints are carried out with short cylindrical pieces of metal, having a smooth perimeter wall, without grooves and notches. Ventilation ducts are provided over an outer perimeter wall of the cylindrical piece and/or standard accessories are provided inside the perimeter wall of the cylindrical piece. A sealing material, commonly a foam, which will harden is provided in between the cylin- drical piece and the ventilation duct/accessory. There is a risk that the hardened sealing material will crack during installation of the ventilation system. The cracks will increase the risk of leaking flue gases. It is also common to seal with a rubber, but the rubber will burn away in case of fire. One aim is to provide a metal sleeve coupling for use in joints, wherein the metal sleeve coupling is provided to seal a joint from leaking flue gases. Another aim of the present invention is to provide an easily handled joint for lightweight ventilation duct systems fulfilling at least the classification EN1366 according to EI30/60. Summary of the invention

According to a first aspect of the invention the aim can be met by means of a metal sleeve coupling for use in a joint between ventilation ducts and/or accessories provided. The ventilations ducts may be, for example, standard ventilation ducts or connectors of metal (often called spiro) having a standardised opening size or heat resisting ventilation ducts or con- nectors according to previous patent applications of the present applicant (see SE2151234- 8 and SE2151233-O) The sleeve coupling has a central axis providing a length of the metal sleeve coupling and sleeve boundary providing a perimeter wall radially of the central axis along the length surrounding an inner sleeve space. The length of the metal sleeve coupling is made up by a first end portion and a second end portion and therebetween an interme- diate portion. Each end portion is provided with at least one groove in the perimeter wall for expandable fire sealing material, the groove is protruding radially inwards or outwards, in the event of a fire the expandable fire sealing material will expand and due to grooves, especially its walls, the expandable fire sealing material will expand radially and thus securely sealing a joint using the metal sleeve coupling and will not leak any flue gases.

According to some embodiments at least one end portion is to be provided inside a flow space of a ventilation duct or connector piece. Said at least one end portion has at least one groove which is protruding radially inwards. Expandable fire sealing material is provided in the groove on an outside of the perimeter wall which is to be facing an inside of a flow space of a ventilation duct or connector piece.

According to some embodiments both end portions are to be provided inside a flow space of a ventilation duct or connector piece and both end portions are having at least one groove which is protruding radially inwards. Expandable fire sealing material is provided in the groove on the outside of the perimeter wall which is to be facing an inside of a flow space of a ventilation duct or connector piece. According to some embodiments at least one end portion is to be provided outside a perimeter of a ventilation accessory, and the at least one end portion having at least one groove which is protruding radially outwards. The expandable fire sealing material is pro- vided in the groove on an inside of the perimeter wall which is to be facing an outside of the ventilation accessory.

According to some embodiments both end portions are to be provided outside a perimeter of a ventilation accessory, and both end portions are having at least one groove which is protruding radially outwards. Expandable fire sealing material is provided in the groove on an inside of the perimeter wall which is to be facing an outside of the ventilation accessory.

According to some embodiments at least one notch is provided in the intermediate portion in the perimeter wall, the at least one notch is protruding radially outwards or inwards; or one inwards and one outwards. Due to the at least one notch a duct or an accessory cannot use more than the portion of the metal sleeve coupling on its end, respectively. Thus, a duct cannot be pushed over the metal sleeve coupling more than into the notch or an accessory cannot be pushed into a metal sleeve coupling more than into the notch. The notch will thus control the joint so that it will be steady and balanced.

According to a second aspect of the invention a joint is provided, the joint comprises a metal sleeve coupling for the joining of either two standard ventilation accessories ; or a standard ventilation accessory and a standard ventilation duct or standard connector piece; or a standard ventilation accessory and a heat resisting ventilation duct or heat resisting con- nector piece, having a mineral fibre layer and an inner layer of steel foil; or a standard ventilation duct or standard connector piece and a heat resisting ventilation duct or heat resisting connector piece; or a heat resisting ventilation duct or connector piece and a heat resisting ventilation duct or connector piece. According to some embodiments the joint between heat resisting elongated ventilation ducts or heat resisting ventilation duct connecting pieces having a mineral fibre layer and an inner layer of steel foil and a standard ventilation duct or standard accessory, the joint comprises a metal sleeve coupling having a first end portion of it attachable in an open end opening of a flow space of a heat resisting ventilation duct or heat resisting connector piece, at an inner side of the inner layer facing the flow space.

According to some embodiments fastening means, such as screws or rivets, are provided for the fastening of the metal sleeve coupling and respectively duct or accessory, preferably the fastening means are provided at the expandable fire sealing material. According to some embodiments the cross-sectional shape is circular for the metal sleeve coupling and the ducts or accessories of the joint.

According to some embodiments a metal flange is positioned inside the open end of a heat resisting ventilation duct or heat resisting connector piece, at an outer side of the inner layer facing the fibre layer or at an inner side of the inner layer facing the flow space. A rim of the flange protrudes radially outwards and is being positioned adjacent an open end of the fibre layer. By having a flange at the open end, the open end is stabilised and if the flange Is positioned on the inner side of the inner layer, it covers the sharp end of the inner layer.

According to some embodiments perforated metal band is provided at the connection between the inner layer and the sleeve coupling, preferably closest to the fibre layer. By means of this band the attachment will be stronger. According to some embodiments the inner layer is clamped between the perforated metal band and the sleeve coupling, or the flange if present.

According to some embodiments the fibre layer comprises mineral fibres and a binder. The mineral fibres should have a melting point over 800 degrees Celsius, compressed into a de- sired duct or connector piece shape, and the inner layer is a steel foil having a thickness of 0,01-0,3 mm, facing the flow space. Thus, the duct or connector piece will be resistant to high temperatures but still have a low weight and be ready for transport and installation.

According to some embodiments an outer layer is provided on an outer side of the fibre layer. The outer layer comprises an aluminium foil and a polyethene layer for attachment to the fibre layer. This make the ducts easier and safer to handle since the fibres are encap- suled inside the outer layer.

According to a third aspect of the invention a method for providing a joint between heat resisting elongated ventilation ducts or heat resisting ventilation duct connecting pieces having a mineral fibre layer and an inner layer of steel foil and a ventilation duct or accessory is provided. One step is positioning a metal sleeve coupling in an open end opening of a flow space of a heat resisting ventilation duct or heat resisting connector piece, at an innermost side facing the flow space and attaching the inner layer to the sleeve coupling by attaching fastening means. Expandable fire sealing material is present in the joint, at least between the inner layer and sleeve coupling, due to the metal sleeve coupling. Another step is connecting a standard ventilation duct or accessory at a portion of the metal sleeve coupling which is protruding out from the open end and which is provided with an expandable fire sealing material at a side facing the standard ventilation duct or accessory.

According to some embodiments, before positioning the sleeve coupling, the step positioning a metal flange inside the open end of a ventilation duct or connector piece, at an outer side of the inner layer facing the fibre layer or at an inner side of the inner layer facing the flow space is provided. A rim of the flange protrudes radially outwards and is positioned adjacent an open end of the fibre layer.

According to some embodiments, before positioning the sleeve coupling, the step positioning a perforated metal band at the open end on an inner side of the fibre layer is provided.

Short description of the drawings The present invention will be described in more detail under referral to the drawings, in which

Fig. la shows a metal sleeve coupling positioned in a joint between a heat resisting elongated ventilation duct or a heat resisting ventilation duct connector piece and a standard ventilation duct or connector piece according to an embodiment of the invention in a sectional, partial view.

Fig. lb shows a metal sleeve coupling positioned in a joint between heat resisting elongated ventilation ducts and/or a heat resisting ventilation duct connector pieces according to an embodiment of the invention in a sectional, partial view. Fig. 2 shows a metal sleeve coupling positioned in a joint between a heat resisting elongated ventilation duct or a heat resisting ventilation duct connector piece and a standard ventilation accessory according to an embodiment of the invention in a sectional, partial view.

Fig. 3 shows a metal sleeve coupling positioned in a joint between a standard elongated ventilation duct or ventilation duct connector piece and a standard ventilation accessory according to an embodiment of the invention in a sectional, partial view.

Fig. 4 shows a metal sleeve coupling positioned in a joint between a standard ventilation accessory or and a standard ventilation accessory according to an embodiment of the invention in a sectional, partial view.

Fig. 5 shows a close-up sectional view showing ingoing layers of a heat resisting elongated ventilation duct or heat resisting ventilation duct connecter piece in more detail.

Fig. 6 shows an embodiment of a metal sleeve coupling having an elongated intermediate portion.

Detailed description of embodiments of the invention In the figures an inventive metal sleeve coupling 16 is shown in different embodiments. The metal sleeve coupling 16 for use in a joint between ventilation ducts/connector pieces 1 and/or ventilation accessories 20. The ventilations ducts 1 may be, for example, standard ventilation ducts 1” or ventilation connector pieces 1” of metal (often called spiro) having a standardised opening size or heat resisting ventilation ducts 1' or heat resisting connector pieces 1' according to previous patent applications of the present applicant (see SE2151234- 8 and SE2151233-0). The metal sleeve coupling 16 has a central axis 21 providing a length of the metal sleeve coupling 16 and sleeve boundary providing a perimeter wall 22 radially of the central axis 21 along the length surrounding an inner sleeve space 23.

The length of the metal sleeve coupling 16 is made up by a first end portion 24 and a second end portion 25 and therebetween an intermediate portion 26. The first end portion 24 is about 30-60%, preferably up to 50 % of the length seen from a first end 27. The second end portion 25 is about 30-60%, preferably up to 50 % of the length seen from a second end 28. The intermediate portion 26 is about 5-60% of the length, for example symmetrically situated, but not necessarily.

Each end portion 24, 25 is provided with at least one groove 30 in the perimeter wall 22. The groove 30 is for expandable fire sealing material 19. Expandable fire sealing material 19 is positioned in the grooves 30. The groove 30 is protruding radially inwards or outwards, as shown in the below described embodiments. In the event of a fire the expandable fire sealing material 19 will expand and due to grooves 30, especially its walls 31, the expandable fire sealing material 19 will expand radially and thus securely sealing a joint using the metal sleeve coupling 16 and will thus not leak any flue gases.

According to some embodiments, such as shown in Figs, la, lb, 2 and 3, at least one end portion, for example the first end portion 24, is to be provided inside a flow space 4 of any type of ventilation duct 1 or connector piece 1. Said at least one end portion has at least one groove 30 which is protruding radially inwards. Expandable fire sealing material 19 is provided in the groove 30 on an outside of the perimeter wall 22 which is to be facing an inside of a flow space 4 of a ventilation duct 1 or connector piece 1.

According to some embodiments, see for example Fig. la and lb, both end portions 24, 25 are to be provided inside a flow space 4 of a ventilation duct 1 or connector piece 1 and both end portions 24, 25 are having at least one groove 30 which is protruding radially inwards. Expandable fire sealing material 19 is provided in the groove 30 on the outside of the perimeter wall 22 which is to be facing an inside of a flow space 4 of a ventilation duct or connector piece. According to some embodiments, such as shown in Figs. 2, 3 and 4, at least one end portion 25 is to be provided outside a perimeter of a ventilation accessory 20, and the at least one end portion 25 having at least one groove 30 which is protruding radially outwards. The s expandable fire sealing material 19 is provided in the groove 30 on an inside of the perimeter wall which is to be facing an outside of the ventilation accessory 20.

According to some embodiments, for example Fig. 4, both end portions 24, 25 are to be provided outside a perimeter of a ventilation accessory 20, and both end portions 24, 25 w are having at least one groove 30 which is protruding radially outwards. Expandable fire sealing material 19 is provided in the groove 30 on an inside of the perimeter wall which is to be facing an outside of the ventilation accessory 20.

According to some embodiments at least one notch 31 is provided in the intermediate por- 15 tion 26 in the perimeter wall 23, the at least one notch 31 is protruding radially outwards or inwards, as shown in the figures. It is also conceivable to have one protruding inwards and one outwards (not shown). Due to the at least one notch 31 a duct 1 or an accessory 20 cannot use more than the portion of the metal sleeve coupling on its end, respectively. Thus, a duct 1 cannot be pushed over the metal sleeve coupling 16 more than into the notch0 31 or an accessory 20 cannot be pushed into a metal sleeve coupling 16 more than into the notch 31. The notch 31 will thus control the joint so that it will be steady and balanced.

In Fig. 6 an embodiment of a metal sleeve coupling 16 is shown. In the shown embodiment the intermediate portion 26 is an elongated intermediate portion 32. This elongated inter-5 mediate portion 32 can be provided in any type of the metal sleeve couplings of this invention. By means of this elongated intermediate portion 32 it is possible to take up any length adjustments needed between ingoing parts (ducts, connector pieces pr accessories) in a ventilation system. In Fig. 6 all the length of the intermediate portion 32 is used. In other cases, just a portion is suitable to be used or, as is shown in broken lines, none of the extra0 portion of the intermediate portion 32 is used. This makes the system more flexible and minimises the need of cutting ducts and so on. In Fig. la a joint between a heat resisting elongated ventilation duct 1' or a heat resisting ventilation duct connecting piece 1' and a standard ventilation duct 1” or a standard ventilation connector piece 1” is shown. The heat resisting elongated ventilation duct 1' or heat s resisting ventilation duct connector piece 1' has a fibre layer 2 and an inner layer 3 of steel foil. The joint comprises a metal sleeve coupling 16 attachable in an open end 12, opening to a flow space 4, of a ventilation duct or connector piece. The sleeve coupling 16 is positioned on an inner side of the inner layer 3, facing the flow space 4. The attachment between the inner layer 3 and the sleeve coupling 16 is provided by means of fastening means w 9, for example rivets or screws 9. Preferably, the attaching of the fastening means, such as the riveting or screwing, is performed through the fibre layer 2, from the outside, through the inner layer 3 and the sleeve coupling 16.

The sleeve coupling 16 is positioned with maximum half of its length within the open end is 12. A protruding portion of the sleeve coupling 16 is to be introduced into a second elongated ventilation duct 1 or ventilation duct connector piece 1, for example being of standard type and attached by means of fastening means, such as rivets or screws 9. Thus, the joint forms a united flow space 4 of the two connected elongated ventilation ducts and/or ventilation duct connector pieces. 0

The fibre layer 2 is made of mineral fibres being compressed with a binder. The mineral fibres should have a melting point over 800 degrees Celsius. The fibres may have a length of at least 10 mm, preferably at least 20 mm or at least 30 mm. In one embodiment the fibre fulfils the classification RAL/40. 5

The mineral fibres are sprayed with a binder solution, which preferably is based on a water- soluble phenolic resin. Thereafter the mineral fibres are compressed and heated in a form to reach its final shape. During the compression and heating the water in the binder solution evaporates and the phenolic resin cures at a temperature around 200 degrees Celsius. The0 amount of binder solution before the forming procedure, i.e., the compression and heating, is between 1-5% by weight. The amount of binder is kept to a minimum in order to avoid adding too much energy into the ventilation duct connector piece, which energy would increase the temperature in case of fire. It is also conceivable to use other binders than phenolic based.

5 After the compression and heating step of the fibre layer, the fibre layer is stiff enough to be self-supported so the ventilation duct or connector piece is self-supported.

The inner layer is a steel foil having a thickness of 0,01-0,3 mm, preferably 0,01-0,2 mm and most preferred 0,03-0,1. In one embodiment the steel foil is a stainless steel foil. As an ex- w ample, AISI 304 may be a suitable steel.

According to an embodiment the heat resisting ventilation duct/connector piece comprises a fibre layer 2, an inner layer 3 and an outer layer 5. The outer layer 5 comprises at least an aluminium foil and a layer of polyethene. The amount of aluminium may be 15-25 gram/m ² . is The amount of polyethene may be 10-50 g/m ² , preferably 15-30 g/m ² .

In Fig. 5 a section of an embodiment of a heat resisting ventilation duct/connector piece 1' is shown. In this embodiment the heat resisting ventilation duct/connector piece 1' is built up by an inner layer 3, a fibre layer 2 and an outer layer 5. The outer layer 5 comprises a0 layer of polyethene 6 closest to the fibre layer 2. The polyethene layer 6 functions as a binder and will stick to the fibre layer 2 by a heating step during production where the polyethene melts and thus bonds the outer layer 5 to the fibre layer 2. Outermost is a layer of aluminium 8 provided. In between a mesh, net or spread glass fibres 7 is provided. The layer of glass fibres 7 increases the strength of the outer layer 5. Preferably, the aluminium 8 is5 black on its outside, which promote heat dissipation. Generally, the outer layer 5 is arranged to enhance the look of the ventilation duct and to encapsule the fibre, which increases health standards when working with the ducts and the possibility to keep clean.

In Fig. la an embodiment of a joint is shown in a cross-sectional detail view. A first end0 portion 24 of a sleeve coupling 16 is arranged in an open end 12 in a heat resisting ventilation duct/connector piece 1' having a fibre layer 2, an inner layer 3 and an outer layer 5. A standard ventilation duct/connector piece 1” is shown in the opposite end portion 25. The sleeve coupling 16 is provided with stiffening grooves 30 and at least one notch 31.

A perforated metal band 11 may be provided between the fibre layer 2 and the inner layer s 3, preferably close to the open end 12. Through any of the perforations fastening means 9, such as a screw or rivet will pass and go through the sleeve coupling 16 to attach the sleeve coupling 16 at the open end 12 of the heat resisting ventilation duct/connector piece by clamping the inner layer 3 between the perforated metal band 11 and the sleeve coupling 16. The perforated metal band 11 reinforces the attachment and is preferably made of steel, w for example stainless steel. It is also possible to position the perforated metal band 11 between the sleeve coupling 16 and the inner layer 3. The perforated metal band 11 may also be dismissed.

A metal flange 10 may be arranged at the open end 12 so that an inner portion 10a pro- 75 trudes into the open end 12 and having a cross-sectional shape corresponding with the cross-sectional shape of the heat resisting ventilation duct/connector piece 1'. An outer portion forms a rim 10b which covers partially an end surface 12a of the fibre layer 2 at the open end 12. The inner portion 10a is positioned either on outer side of the inner layer 3 facing the fibre layer 2, or preferably on an inner side of the inner layer 3, facing the flow0 space 4. In the figures a circular cross-sectional shape has been shown but it is conceivable to have any cross-sectional shape, such as quadratic, hexagonal and so on.

In Fig. la an embodiment is shown where an open end 12 of a heat resisting elongated ventilation duct 1' or a heat resisting ventilation duct connector piece 1' is provided with a5 flange 10 positioned with its inner portion 10a on the inner side of the inner layer 3. In such a way the open end is protected from an edge of the inner layer 3, which can be sharp. In this embodiment a perforated metal band 11 is provided between the inner layer 3 and the fibre layer 2. This embodiment is also provided with an outer layer 5 which reaches over at least a portion of the open end surface 12a, comprising at least a polyethene layer 6 and an0 aluminium layer 8. The outer layer 5 may also comprise a glass fibre layer 7. Up to half of the length of the sleeve coupling 16, the first end portion 24, is present within the open end 12 and is screwed or riveted to the flange 10, inner layer 3 and the perforated metal band 11. A second end portion 25 of the remaining protruding sleeve coupling 16 may be introduced into an open end 12 of another ventilation duct 1 or connector piece 1 and s attached by means of screws or rivets 9.

A sealing material 19 is provided in order to seal the joint. For example, an expandable fire acrylic sealing material may be positioned between the inner layer 3 and the sleeve coupling 16 and any therebetween ingoing layers, such as a flange 10. It is also possible to provide a w sealing material where the screws or rivets 9 are to be provided.

As a matter of fact, it is possible to produce all or some of the heat resisting elongated ventilation ducts l'and/or heat resisting ventilation duct connector pieces 1' with a flange 10 and possible perforated metal band 11 at at least one of the open ends 12. Thus, the is heat resisting ventilation duct/connector piece is readyfor attachment to build up a system.

A joint according to the invention may use none, one or more of the above described parts more than the inner layer 3, the sleeve coupling 16 and fastening means 9. It is also conceivable to arrange the ingoing parts in any order seen from a centre of the open end and0 radially outwards, unless contradictory. The shown embodiments are only exemplifying the invention.