FIELD OF THE INVENTION

The present invention relates to a type of union mainly used for joining stainless steel pipes. The union is preferably designed in such a way that it has no horizontal surfaces or cavities having a horizontal opening whether it is installed in a vertical or horizontal pipeline. This design ensures that no water remains on the surface after cleaning has taken place BACKGROUND OF THE INVENTION

Ever since welding of stainless steel became possible the design of unions for joining the stainless steel pipes has followed the same trend. A welding liner placed against a welding male part pressed together by an external female nut. Illustrations of this trend can be seen in the enclosed figs. 1 to 5 illustrating various standards for unions.

Common for all the standards is that the units are suitable for installation in horizontal pipelines, but if installed in vertical pipelines some water will remain in the cavities e.g. between the nut and the welding liner/welding male part after cleaning. Thus, although great care is taken to clean the units, experience has shown that the known units are prone to accumulate dirt wherein bacteria can grow, often resulting in contamination in dairy installations where for instance milk and other components are dosed in open containers prior to sealing such containers.

In most up to date food factories processing takes place in ultra clean rooms, and in such rooms it is not acceptable to have water or dirt remaining on part of the equipment thus creating a source for bacteria growth.

Hence, an improved union would be advantageous, and in particular a more efficient and/or reliable union would be advantageous.

OBJECT OF THE INVENTION An object of the present invention is to provide an alternative to the prior art.

In particular, it may be seen as a further object of the present invention to provide a unioin that solves the above mentioned problems of the prior art with respect to water and/or dirt accumulation.

SUMMARY OF THE INVENTION

Thus, the above described object and several other objects are intended to be obtained in a first aspect of the invention by providing a union comprising

- a female part in the form of a tubular element having an inner diameter and comprising an annular outer end surface, an annular inner end surface and an inner recessed section extending from said outer end surface to said inner end surface, the first tubular element further comprising an internal thread provided in at least a part of the wall of the inner recessed section; - a tubular welding liner having an inner diameter being at least substantial equal to the inner diameter of the female part and comprising at one end an outwardly protruding flange extending through-out the circumference of the welding liner, the outer geometry of the flange mate the internal geometry of the recess at the inner end surface so as to provide the tubular welding liner to be accommodated in a snug-fit in the inner recessed section with a centre axis of the tubular welding liner aligned with a centre axis of the female part;

an inner tubular seal having an inner diameter being at least substantial equal to the inner diameter of the female part, and an outer geometry allowing arrangement of the inner tubular seal to abut said inner end surface;

a male part having an internal diameter being larger than an outer diameter measured outside the flange, of the welding liner, the male part having an external thread provided along a section of the male part, said external thread is configured to cooperate with the internal thread on the female part to screw the male part into the female part and to clamp said flange and said inner tubular seal in-between said inner end surface and an end surface of the male part. By "measured outside the flange" is typically meant the part of the flange 11 extending axially away from the flange and to which the pipe is to be welded (e.g. as illustrated in fig. 6). Further embodiments and aspects of the invention are presented in the following as well as in the accompanying claims.

BRIEF DESCRIPTION OF THE FIGURES

Known devices are discribed in figures 1-5 where:

Fig. 1 is an illustration of a union according the Danish standard "DS",

Fig. 2 is an illustration of a union according to the Swedish standard "SMS",

Fig. 3 is an illustration of a union according to the German standard "DIN",

Fig. 4 is an illustration of a union according the ISO standard "ISO/IDF", Fig. 5 is an illustration of a union according the ISO standard "ISO/RJI". The present invention and in preferred embodiments thereof will now be described in more detail with reference to the accompanying figures 6, 7 and 8. The figures show ways of implementing the present invention and are not to be construed as being limiting to other possible embodiments falling within the scope of the attached claim set. The dimensions indicated in the figures are not to be construed as limiting the scope of the invention.

Fig. 6 is a schematical illustration of a first preferred embodiment of a union according to the invention, and Fig. 7 is a schematical illustration of a second preferred embodiment of a union according to the invention.

Fig. 8 is a schematical illustration of a third preferred embodiment of a union according to the invention. Fig. 9 is a schematical illustration of a preferred embodiment of a device according to the invention.

Fig. 10 is a schematical illustration of a dovetail groove, which is a preferred shape of the longitudinally extending grooves.

Fig. 11 is an illustration of an embodiment, where the female part has a protrusion on an inner end surface. Fig. 12 is an illustration of an embodiment, where the male part has a protrusion on a inner surface of the male part, which clamps the end tubular seal, when the male part is screwed into the female part.

Fig. 13 is an illustration of an embodiment, where the welding liner has a protrusion on the outwardly protruding flange.

Figs. 14-16 illustrates the features disclosed in figs. 11-13 according to a specific embodiment. Fig. 17 is an illustration of an embodiment, where the male part has a protrusion on a inner surface of the male part and where the inner end surface has a mechanical stop having an abutment surface.

Figs. 18 and 19 is an illustration of an embodiment, where the inner end surface has a mechanical stop having an abutment surface.

Fig. 20 is an illustration of an embodiment, where the male part has a mechanical stop having an abutment surface allowing the flange to abut against the mechanical stop.

DETAILED DESCRIPTION OF EMBODIMENTS

A first embodiment of a union according to the invention can be seen in fig. 6, where 1 is the welding liner, 2 is the female part and 3 is the male part pressing 1 and 2 together when the male part 3 is screwed into the female part 2. In fig. 6 and 7, the numbers 4, 5 and 6 denote rubber gaskets as will be elucidated below.

Fig. 6 shows in detail, a union according to a first embodiment of the invention; it is noted that the upper part of fig. 6 (as well as in fig. 7 and 8) illustrates the union with a cutaway to reveal the interior of the union illustrated by cross- hatching. The following description covers both the embodiments shown in fig. 6 and 7 if not otherwise stated. The union in fig. 6 comprises a female part 2 in the form of a tubular element having an inner diameter Dl. The outer end 18 of the female part 2 is for being welded to a pipe to be united with the union. By "a pipe to be united with the union" is typically meant that the pipe is to be united with another pipe by use of the union. The female part 2 has an annular outer end surface 7 (distant to the outer end 18), an annular inner end surface 9 and an inner recessed section 8 extending from the outer end surface 7 to the inner end surface 9. As will be disclosed below, the inner end surface 9 is designed to form a sealing surface. The female part 2 further comprises an internal thread 10 provided in at least a part the wall of the inner recessed section 8.

The union also comprises a tubular welding liner 1 being a separate part of the union and is for being welded to another pipe to be united the union. The welding liner has an inner diameter being at least substantially equal to the inner diameter Dl of the female part 2 and comprises at one end an outwardly protruding flange 11, preferably having a constant outer diameter, extending through-out the circumference of the welding liner 1. This flange 11 cooperates with the inner end surface to form a seal (with a seal clamped in between as disclosed below).

The outer geometry of the flange 11 mate the internal geometry of the recess at the inner end surface 9 so as to provide for the tubular welding liner 1 to be accommodated in a snug-fit in the inner recessed section 8 with a centre axis of the tubular welding liner 1 aligned with a centre axis of the female part 2. By snug-fit is preferably meant that the flange 11 may be introduced into the female part 2 without the need for altering mechanically the flange 11 while at the same time being kept in a fixed position relatively to the female part 2 to align the centre axes of the female part 2 and the welding liner 1.

To provide a fluid tight seal, the union has an inner tubular seal 4, being a separate part, having an inner diameter being at least substantially equal to the inner diameter Dl of the female part 2, and an outer geometry allowing

arrangement of the inner tubular seal 4 to abut said inner end surface 9 of the female part 2 and an end surface of the welding liner 1. The seal 4 is preferably made from a resilient material, such as rubber.

The union further comprises a male part 3, being a separate part, having an internal diameter being larger than an outer diameter, measured outside the flange 11, of the welding liner 1 to allow the pipe to be welded to the welding liner 1 to extend within the male part 3. By "measure outside the flange 11" is typically meant the part of the flange 11 extending axially away from the flange and to which the pipe is to be welded (as illustrated in fig. 6). The male part 3 has an external thread 23 provided along a section of the male part 3. The external thread 23 is configured to cooperate with the internal thread 10 on the female part 2 to screw the male part 3 into the female part 2 and to clamp the flange 11 of the welding liner 1 and the inner tubular seal 4 in-between the inner end surface 9 of the female part 2 and an end surface of the male part 3.

As can be seen from figs. 6 and 7, water will drain from the surface of the assembled unions, whether the union is installed in a vertical or horizontal pipeline.

A further advantage by the design shown is that by using the male part for fastening instead of the female nut, the outer dimensions of the union can be reduced considerably compared to the dimensions of the conventional unions. This naturally reduces material cost as well as manufacturing cost.

In the dairy industry sterile products are becoming more and more popular, the union according to the invention is well suited for aseptic production as the inner surface of the rubber gasket (seal) item 4 in figs. 6, 7 and 8 is provided to be flush with the inner dimension of the pipeline. Herein, the term "flush" is typically used to mean that two or more surface are dimensioned or arranged so that the presence of cavities is aimed at being avoided - ideally - providing a seamless connection between two or more parts. Ideally refers to the production accuracy often setting a limit for when something is categorized as seamless.

Herein, the term "during use" is used frequently and is typically intended to mean the situation where the union is assembled to unite two pipes.

The male part 3 may preferably have a ring shaped section 12 defining an annular surface 13 facing, during use, the annular end surface 7 of the female part 2. This, ring shaped section 12, may advantageously be occupied by an outer tubular seal 6 being clamped, during use, in-between the annular surface 13 of the male part 3 and the outer end surface 7 of the female part 2. Also this seal 6 may preferably be made from a resilient material, such as rubber. The seal 6 is preferably shaped so that the transition between the male part and female part is flush. A section of the female part 2 extending from the outer end surface 7 and the ring shaped section of the male part 3 both have an outer cylindrical shape with at least substantially the same diameter, and the outer diameter of the outer tubular seal 6 is at least substantially equal to the diameter of said outer cylindrical shape, typically measured when the outer tubular seal 6 is being clamped. This is intended to provide a seamless transition between the female and male parts 2, 3 of the union as seen from the outside of the union.

To prevent liquid - or in general dirt - from entering into the union along the pipe being welded to the welding line 1, the union may further comprise an end tubular seal 5 arranged to create a seal between an outer surface of a pipe extending inside the male part 3 and an inner surface of the male part 3. Such an end tubular seal 5 is typically configured by its shape to provide a flush transition between the male part 3 and the outer surface of the pipe. The seal 5 may preferably be made from a resilient material, such as rubber. Reference is now made specifically to the first embodiment shown in fig. 6 illustrating the end tubular seal 5 which has an L-shaped cross section. The male part 3 comprises an inner groove 14 configured for receiving a section of the end tubular seal 5 - as illustrated the inner groove 14 receives the outwardly protruding part of the tubular seal 5.

Reference is now made specifically to the second embodiment shown in fig. 7 illustrating the end tubular seal 5 cylindrically extending internally in the male part 3, during use, from an end surface 15 of the male part 3. The opening in the male part distant from the threaded section may be tapered (with the least diameter at the outer most position of the opening) to producing a clamping action to clamp the tubular seal 5 in-between the male part 3 and the pipe welded to the welding liner 1. To allow a tool to grip on the male part 3 to ease assembly, the male part 3 comprises longitudinally extending grooves 16.

While such longitudinally extending grooves 16 may accumulate water and/or dirt depending on the orientation in which the union is installed, the male part 3 may be provided with a circular extending groove 17, preferably being arranged so that each of the longitudinal extending grooves 16 opens into the circular extending groove 17, preferably the depth of the circular extending groove 17 is bigger than or equal to the depth of the longitudinal extending grooves 16. As illustrated, such a circular extending groove 17 is typically wedge-shaped which further reduces the risk that water and/or dirt accumulates on the union.

Grooves like 16 and 17 may also be provided to the female part 2.

With reference to figs. 17, 18 and 19, the inner end surface 9 may preferably comprise a mechanical stop 25 comprising an abutment surface allowing the flange 11 to abut against the mechanical stop 25.

When the union is assembled, an abutment surface of the mechanical stop 25 and the flange 11 are pressed together, creating a space between part of the flange 11 and part of the inner end surface 9. The space created between part of the flange 11 and part of the inner end surface 9, ensures that the inner tubular seal 4 cannot be compressed to such a degree that its ability to function as a seal is compromised. A third preferred embodiment of a union according to the invention can be seen in fig. 8, where 1 is the welding liner, 2 the female part and 3 is the male part. The female part press 1 and 3 together when the female part 2 is screwed on to the male part 3. In fig. 8 the numbers 4, 5 and 6 denote rubber gaskets as will be further elaborated below.

Fig. 8 shows in details a union according to a third embodiment of the invention. As in fig. 6 and 7, the upper part of fig. 8 illustrates the union with a cutaway to reveal the interior of the union illustrated by cross-hatching. The union in fig. 8 comprises a female part 2 in the form of a tubular element having an annular outer end surface 7, which is designed to form a sealing surface as will be disclosed below. The female part 2 also has an annular inner end surface 9 and an inner recessed section 8, which extends from the outer end surface 7 to the inner end surface 9. Further, the female part 2 has an internal thread 10 provided in at least a part of the wall of the inner recessed section 8.

The union also comprises a tubular welding liner 1 with an inner diameter Dl. The tubular welding liner 1 is a separate part of the union and is meant to be welded to a pipe to be united by use of the union. The tubular welding liner 1 has at one end an outwardly protruding flange 11, preferably having a constant outer diameter, extending through-out the circumference of the welding liner 1.

The outer geometry of the flange 11 mate the internal geometry of the recess at the inner end surface 9 such that the tubular welding liner 1 can be

accommodated in a snug-fit in the inner recessed section 8 with a centre axis of the tubular welding liner 1 aligned with a centre axis of the female part 2. By snug-fit is preferably meant that the flange 11 may be introduced into the female part without the need for altering mechanically the flange 11 while at the same time being kept in a fixed position relatively to the female part 2 to align the centre axes of the female part 2 and the welding liner 1. To provide a fluid tight seal, the union has an inner tubular seal 4 with an inner diameter that is at least substantially equal to the inner diameter Dl of the welding liner 1, and an outer geometry allowing arrangement of the inner tubular seal 4 to abut said flange 11. The seal 4 is preferably made from a resilient material, such as rubber.

The union further comprises a male part 3, being a separate part, having an internal diameter at least substantially equal to the inner diameter Dl of the welding liner 1. The outer end 22 of the male part 3 is meant to be welded to a pipe that is to be united with another pipe by use of the union. The male part 3 has an external thread 23 provided along a section of the male part 3, which external thread 23 is configured to cooperate with the internal thread 10 on the female part 2 to screw the male part 3 into the female part 2 and to clamp the flange 11 of the welding liner 1 and the inner tubular seal 4 in-between the inner end surface 9 of the female part 2 and an end surface of the male part 3.

The male part 3 may preferably have a ring shaped section 12 defining an annular surface 13 facing, during use, the annular end surface 7 of the female part 2. This ring shaped section 12 may advantageously be occupied by an outer tubular seal 6 being clamped, during use, in-between the annular surface 13 of the male part 3 and the outer end surface 7 of the female part 2. The seal 6 may preferably be made from a resilient material, such as rubber, and is preferably shaped so that the transition between the male part 3 and female part 2 is flush.

A section of the female part 2 extending from the outer end surface 7 and the ring shaped section of the male part 3 both have an outer cylindrical shape with at least substantially the same diameter, and the outer diameter of the outer tubular seal 6 is at least substantially equal to the diameter of said outer cylindrical shape, typically measured when the outer tubular seal 6 being clamped. This is intended to provide a seamless transition between the female and male parts 2, 3 of the union as seen from the outside of the union.

To prevent liquid - or in general dirt - from entering into the union along the pipe being welded to the welding line 1, the union may further comprise an end tubular seal 5 arranged to seal between an outer surface of the welding liner 1 extending inside the female part 2 and an inner surface of the female part 2. Such an end tubular seal 5 is typically configured to provide a flush transition between the female part 2 and the outer surface of the pipe.

The end tubular seal 5 may preferably have an L-shaped cross section and the welding liner 1 may preferably comprise an inner groove 14 configured for receiving a section of the end tubular seal 5 - as illustrated in fig. 8 the inner groove 14 receives the outwardly protruding part of the tubular seal 5. The seal 5 may preferably be made from a resilient material, such as rubber.

To allow a tool to grip on the female part to ease assembly, the female part 2 comprises longitudinally extending grooves 16. While such longitudinally extending grooves 16 may accumulate water and/or dirt depending on the orientation in which the union is installed, the female part 2 may be provided with a circular extending groove 17, preferably being arranged so that each of the longitudinal extending grooves 16 opens into the circular extending groove 17, preferably the depth of the circular extending groove 17 is bigger than or equal to the depth of the longitudinal extending grooves 16. As illustrated, such a circular extending groove 17 is typically wedge-shaped which further reduces the risk that water and/or dirt accumulates on the union.

Grooves like 16 and 17 may also be provided to the male part 3.

The longitudinally extending grooves 16 of a union according to the present invention may preferably be dovetail grooves as shown in fig. 10. Dovetail grooves have a trapezoidal cross section with the bottom of the groove being wider than the top of the groove. The dovetail groove has the advantage that the groove can be made with less depth than the square grooves, as the fastening tool gets a better grip. Thus, the outer diameter of the union can be reduced which reduces the production cost. Advantageously, the bottom of the longitudinal groove of a union according to the present invention can have a slight angle with respect to the centre axis of the union. This allows for proper draining after cleaning. A union as illustrated in fig. 8 has the advantage that upon unscrewing the female part 2 and moving the female part away from the flange 11, the pipe welded to the tubular welding liner 1 may be moved vertically (with reference to the orientation of fig 8) without the need for a horizontal movememt (again with reference orientation of fig. 8). This is particular advantageous in relation to the embodiment shown in fig. 9, which is disclosed below.

With reference to fig. 20, the male part 3 may preferably comprise a mechanical stop 25 comprising an abutment surface allowing the flange 11 to abut against the mechanical stop 25.

When the union is assembled, an abutment surface of the mechanical stop 25 and the flange 11 are pressed together, creating a space between part of the flange 11 and part of the male part 3. The space created between part of the flange 11 and part of the male part 3, ensures that the inner tubular seal 4 cannot be compressed to such a degree that its ability to function as a seal is compromised.

Further embodiments are described with reference to figs. 11 - 17. In a further embodiment, one or more surfaces which comes into contact with a seal, when the male part 3 is screwed into the female part 2, may comprise a protrusion 24.

By surfaces is meant surfaces of a part comprised in the union such as e.g. the inner end surface 9, a surface on the outwardly protruding flange 11 or an inner surface of the male part 3. By inner surface of the male part 3 is meant a surface, which faces towards the centre axis of the union.

An effect of the protrusion 24 is to limit or counter movement of the seal with which it makes contact. In an embodiment, the surface which comes into contact with a seal, when the male part 3 is screwed into the female part 2, is the inner end surface 9 of the female part 2 and the seal is the inner tubular seal 4. In an embodiment the surface which comes into contact with a seal, when the male part 3 is screwed into the female part 2, is a surface on the outwardly protruding flange 11 and the seal is the inner tubular seal 4.

In an embodiment, the inner surface of the male part 3, which clamps the end tubular seal 5, when the male part 3 is screwed into the female part 2, has a protrusion 24.

In an embodiment, the protrusion 24 may be shaped such that it has one or more sharp edges, which come into contact with a seal. Preferably, the protrusion 24 will have a pointed shape.

In another embodiment, the protrusion 24 may have a blunt shape, i.e. without sharp edges. In a further embodiment, the protrusion 24 extends through-out the

circumferential surface defined by the surface which comes into contact with a seal.

A union according to the present invention is typically rotationally symmetric along a longitudinal direction except for the longitudinally extending grooves 16 and the pitch of the threads, thereby providing a union with at least internal circular cross sections (perpendicular to the longitudinal direction defined by the pipes united). A union according to the present invention is typically made from stainless steel and is typically produced by a turning process, and if considered necessary, followed by a polishing process.

The unions according to the present invention can be used in a device for transferring fluid, such as liquid in a dairy production facility, as shown in fig. 9. The device comprises a first fluid connection 19, a connection pipe 21 and a plurality of second fluid connections 20. The second fluid connections 20 are arranged along a perimeter of a circle having its centre coinciding with the centre of the first fluid connection. A fluid connection is a pipe, which can transport fluid and which is to be connected to a union by welding.

The connection pipe 21 is connected at one end to the first fluid connection and at the other end to one of the second fluid connections by use of unions. In such a device one can advantageously connect one end of the connection pipe 21 to a first fluid connection 19 by use of a union according to the first or second preferred embodiments and the other end of the connection pipe to one of the second fluid connections 20 by a union according to the third preferred

embodiment. Or in general, by use of a unit according to one of the embodiments at one end and according to one of the embodiments at the other end.

By loosening the male nut 3 at the first fluid connection A and unscrewing the female nut 2 at the second fluid connection the connection pipe 21 is free to rotate to another second fluid connection, e.g. from B to C in fig. 9.

As mentioned above, in embodiment where unions as disclosed in fig. 9 are used to connect the connection pipe 21 at position e.g. A, B and C in fig. 9, where male parts 3 are arragned at the various positions and female parts 2 are arranged on the connection pipe 21. To change the position of the connection pipe, the female part 2 can be loosened at connection A and unscrewed at position B. Then the pipe 21 can be rotated to position C (while the male and female parts 2, 3 remains threaded) at which position the female part 2 is screwed onto a male part 3 at position C, and the female part 2 at position A is fastened. Thereby, the connection pipe 21 can be positioned in the new position by a substantial rotational movement only. It is noted that the male parts 3 remain in their positions.

The dimensions, if not followed by a degrees sign, indicated in the figures may be interpreted as given in millimetres. Although the present invention has been described in connection with the specified embodiments, it should not be construed as being in any way limited to the presented examples. The scope of the present invention is set out by the accompanying claim set. In the context of the claims, the terms "comprising" or "comprises" do not exclude other possible elements or steps. Also, the mentioning of references such as "a" or "an" etc. should not be construed as excluding a plurality. The use of reference signs in the claims with respect to elements indicated in the figures shall also not be construed as limiting the scope of the invention. Furthermore, individual features mentioned in different claims, may possibly be advantageously combined, and the mentioning of these features in different claims does not exclude that a combination of features is not possible and advantageous.

LIST OF REFERENCE SYMBOLS USED

1 Tubular welding liner

2 Female part

3 Male part

4 Inner tubular seal

5 End tubular seal

6 Outer tubular seal

7 Outer end surface

8 Inner recessed section

9 Inner end surface

10 Internal thread

11 Outwardly protruding flange

12 Ring shaped section

13 Annular surface of male part

14 Inner groove

15 End surface of the male part

16 Longitudinal extending groove

17 Circular extending groove

18 Outer end of female part

19 First fluid connection

20 Second fluid connection

21 Connection pipe Outer end of male part External thread Protrusion

Mechanical stop