Technical field

The invention relates to a lining device for lining a porthole in an end plate of a heat exchanger and a heat exchanger comprising such a lining device.

Background art

Different kinds of heat exchangers exist, for example plate heat exchangers, shorter referred to as PHEs. PHEs typically consist of two end plates in between which a number of heat transfer plates are arranged in an aligned manner, i.e. in a stack or pack. In one type of well-known PHEs, the so called gasketed plate heat exchangers, gaskets are arranged between the heat transfer plates. The end plates, and therefore the heat transfer plates, are pressed towards each other by some kind of tightening means, whereby the gaskets seal between the heat transfer plates. Parallel flow channels are formed between the heat transfer plates, one channel between each pair of heat transfer plates. Two fluids of initially different temperatures, which are fed to/from a PHE through inlet/outlet portholes in the end plates, can flow through every second channel for transferring heat from one fluid to the other. The fluids enter/exit the channels through inlet/outlet portholes in the heat transfer plates communicating with the inlet/outlet portholes in the end plates.

The fluids flowing through a PHE can be more or less corrosive and the heat transfer plates are typically adapted to the characteristics of the fluids. For example, the heat transfer plates of a PHE arranged to receive less corrosive fluids may be made of stainless steel while the heat transfer plates of a PHE arranged to receive more corrosive fluids may be made of titanium.

Typically, the end plates are much thicker than the heat transfer plates and therefore made of a less expensive and less corrosion resistant material than the heat transfer plates, for example carbon steel. To protect the portholes in the end plates from the fluids to prevent corrosion of the end plates, the portholes are typically lined by means of lining devices. A known lining device for a plate heat exchanger is illustrated in

US 6775909. It includes first and second deep-drawn parts which each has a pipe portion and an abutment portion. The first and second parts are inserted into a porthole of an end plate from opposite sides of the end plate such that their pipe portions overlap inside the porthole. The pipe portions are connected to each other by a weld joint. The first part has a greater material thickness than the second part at the overlap. Even if this lining device is widely used and fill the desired purpose, there is still room for improvements. Summary

An object of the present invention is to provide a lining device for lining a porthole in an end plate of a heat exchanger which is improved as compared to prior art lining devices. The basic concept of the invention is to provide a lining device comprising more than two parts such that the parts corresponding to the first and second parts of the prior art lining device above can be made shorter. Another object of the present invention is to provide an improved heat exchanger comprising such a lining device. The lining device and the heat exchanger for achieving the objects above are defined in the appended claims and discussed below.

A lining device for lining a porthole in an end plate of a heat exchanger according to the present invention comprises a first part and a second part. The first part includes a tubular inner portion having an inside. The tubular inner portion is arranged to extend inside the porthole. The first part further includes an outer portion arranged to extend on an outside of the end plate. The second part includes a tubular inner portion having an inside. The tubular inner portion is arranged to extend inside the porthole. The second part further includes an outer portion arranged to extend on an inside of the end plate. The lining device is characterized in further comprising a tubular third part having a wall thickness and being arranged to extend inside the porthole. The third part is arranged to engage with the tubular inner portions of the first and second parts to couple the first and second parts. A first section of the third part is arranged to overlap an overlap section of the tubular inner portion of the first part in a first overlap, and a second section of the third part is arranged to overlap an overlap section of the tubular inner portion of the second part in a second overlap.

By the provision of the third part for coupling the first and second parts to each other, the first and second parts need not be arranged to overlap or even contact each other. Accordingly, looking at lining devices arranged to fit one and the same end plate, the tubular inner portions of the first and second parts may be made shorter than the pipe portions of the first and second parts of the prior art lining device above. The longer the third part is, the shorter the tubular inner portions of the first and second parts may be.

Draw-pressing and stretch-forming are two different deep-drawing techniques. Typically, stretch-forming is cheaper and results in better shape control than draw-pressing. However, draw-pressing may have to be used when relatively long objects are to be made. Since the tubular inner portions of the first and second parts may be made relatively short in accordance with the present invention, the first and second parts of the lining device according to the present invention may be stretch -formed, rather than draw-pressed, which is an economical advantage and which also results in better shape control and therefore a better fit. The known lining device mentioned above may however demand draw-pressing depending on its desired final dimensions.

Further, the tubular inner and outer portions of the first part may be integrally formed, and the tubular inner and outer portions of the second part may be integrally formed.

The first and second parts of the known lining device mentioned above are permanently connected, more particularly connected to each other by a welding joint. Such welding joints are relatively costly. Also, the welding requires that at least one of the first and second parts has a relatively large wall thickness. According to an embodiment of the present invention, the third part may be arranged to engage non-permanently with the tubular inner portion of the first part and the tubular inner portion of the second part. Thus, according to the present invention, the first, second and third parts may be arranged to releasably, detachably or removably engage with each other, i.e. they may be repeatedly and non-destructively mountable/connectable and demountable/disconnectable. Thereby, a less expensive connection of the lining device parts, requiring no or relatively simple tools or equipment, is enabled. Thus, mounting of the lining device to the end plate porthole, and maintenance and/or replacement of the lining device, may be facilitated and faster. Also, since no welding is involved, it is not necessary that at least one of the first and second parts has a relatively large wall thickness, which is also economically beneficial.

The lining device may further comprise a first sealing means arranged to seal between the tubular inner portion of the first part and the third part, and a second sealing means arranged to seal between the tubular inner portion of the second part and the third part. Thereby, a tight lining device able to fully protect the porthole may be achieved.

The first and second sealing means may be of different kinds. For example, the first sealing means may comprise an annular first gasket arranged to extend between the first and third parts within the first overlap. Similarly, the second sealing means may comprise an annular second gasket arranged to extend between the second and third parts within the second overlap.

The lining device may be such that the section of 1 ) the first section of the third part, and 2) the overlap section of the first part, that is arranged to be positioned closest to a cylindrical inner wall of the end plate defining the porthole, comprises an annular recess for receiving the first gasket. Similarly, the section of 1 ) the second section of the third part, and 2) the overlap section of the second part, that is arranged to be positioned closest to the cylindrical inner wall, may comprise an annular recess for receiving the second gasket. In other words, either the first or the third part may comprise a recess for receiving the first gasket, while either the second or the third part may comprise a recess for receiving the second gasket. It is also conceivable that the first and third parts both comprise a recess for receiving the first gasket, and/or that the second and third parts both comprise a recess for receiving the second gasket. These recesses facilitate arranging and maintaining the first and second gaskets in the correct positions. The first and second gaskets may be of different types. For example, they may be o-rings whereby reliable and mechanically simple seals may be achieved.

The first, second and third parts of the lining device may be positioned differently in relation to each other. The third part may be arranged to at least partly surround the tubular inner portions of the first and second parts.

Alternatively, the tubular inner portions of the first and second parts may be arranged to at least partly surround the third part. According to the latter embodiment, an outside of the third part may be arranged to face the inside of the tubular inner portion of the first part within the first overlap, and the inside of the tubular inner portion of the second part within the second overlap. This means that the tubular inner portions of the first and second parts will be arranged between the third part and the cylindrical inner wall of the end plate defining the porthole when the lining device is fitted to the end plate.

The lining device may be such that the first part comprises a first locking means and the third part comprises a first locking means. The first locking means of the first and third parts may be arranged to engage with each other so as to limit movement of the first and third parts in relation to each other in a direction parallel to a longitudinal center axis of the third part.

Alternatively/additionally the lining device may be such that the second part comprises a second locking means and the third part comprises a second locking means. The second locking means of the second and third parts may be arranged to engage with each other so as to limit movement of the second and third parts in relation to each other in a direction parallel to the longitudinal center axis of the third part. By means of these locking means, a correct assembly of the parts of the lining device may be obtained and maintained.

The locking means may be formed in different ways. For example, the first locking means of the first part may comprise an annular first bulge on the inside of the tubular inner portion of the first part, the second locking means of the second part may comprise an annular second bulge on the inside of the tubular inner portion of the second part, the first locking means of the third part may comprise an annular first edge of the third part and the second locking means of the third part may comprise an annular second edge of the third part. This embodiment enables locking of the third part between the annular first and second bulges of the first and second parts in a stable and mechanically straightforward way.

A height of the first and second bulges may be essentially equal to the wall thickness of the third part. Thereby, a top surface of the first and second bulges may be arranged flush with an inner surface of the third part when the lining device is assembled, which may result in a relatively small disturbance of a fluid flow through the lining device and which may also be beneficial from a hygienic point of view.

The lining device may be such that a wall thickness of the tubular inner portion of the first part, a wall thickness of the tubular inner portion of the second part and the wall thickness of the third part are essentially the same. This may enable use of the same tool for manufacturing the first and second parts.

The outer portions of the first and second parts of the lining device may have different shapes, e.g. be shaped for connection to pipe conduits or the like, and include threads, bayonet mountings etc. According to one embodiment at least one of the outer portion of the first part and the outer portion of the second part comprises a flange extending substantially radially outwardly from the respective tubular inner portion.

The lining device may be such that at least one of the outer portion of the first part and the outer portion of the second part is arranged to abut a respective one of an outside wall and an inside wall of the end plate. Such an embodiment may enable automatic fixing of at least one of the first and second parts to the endplate when the corresponding tubular inner portion is inserted into the porthole of the end plate and engages with the third part. If said at least one of the outer portion of the first part and the outer portion of the second part comprises a flange, an inside of this flange may be arranged to abut the inside or outside wall of the end plate. A heat exchanger according to the present invention includes a lining device according to any of the preceding claims and an end plate comprising a porthole, wherein the porthole is lined with the lining device.

Of course, the advantages associated with the different embodiments of the lining device discussed above are advantageous also for a heat exchanger comprising the lining device.

Still other objectives, features, aspects and advantages of the invention will appear from the following detailed description as well as from the drawings.

Brief description of the drawings

The invention will now be described in more detail with reference to the appended schematic drawings, in which

Fig. 1 is a front view of a heat exchanger,

Fig. 2 is a side view of the heat exchanger of Fig. 1 ,

Fig. 3 is a front view of a part of an end plate provided with a lining device,

Fig. 4 is a cross-section through the part of the end plate and the lining device of Fig. 3, taken along line A-A in Fig. 3, and

Fig. 5 is an enlargement of a part B of the cross section of Fig.4.

Fig. 6 corresponds to Fig. 5 for an alternative lining device.

Fig. 7 is a cross-section through an alternative lining device.

Detailed description

In Figs. 1 and 2 a gasketed plate heat exchanger 2 is illustrated. It comprises a first end plate 4 and a second end plate 6, which sometimes are referred to as frame plate and pressure plate, respectively. The end plates 4 and 6 are made of carbon steel. The end plate 4, which has an inside wall 5 on an inside I and an outside wall 7 on an outside O, comprises four portholes 8, 10, 12 and 14. A portion of the end plate 4 comprising the porthole 8 is also visible in Figs. 3, 4 and 5.

The heat exchanger further comprises a pack 16 of mutually aligned stainless steel heat transfer plates 18 arranged between the end plates 4 and 6. An outermost one of the heat transfer plates 18 is arranged to face the inside wall 5 of the end plate 4. The heat transfer plates are each provided with a corrugation pattern of ridges and valleys in relation to a central extension plane c-c of the heat transfer plates. Further, each of the heat transfer plates 18 comprises four portholes, except for the heat transfer plate closest to the end plate 6, which has no portholes. The portholes of the heat transfer plates 18 and the end plate 4 are aligned with each other so as to create four ports extending inside the plate heat exchanger 2.

In the plate pack 16 the heat transfer plates 18 are separated from each other by gaskets (not visible in the figures) arranged in gasket grooves in the heat transfer plates extending along longitudinal outer edges and around the portholes of the heat transfer plates. The heat transfer plates together with the gaskets form parallel channels communicating with the ports and arranged to receive two fluids for transferring heat from one fluid to the other. To this end, a first fluid is arranged to flow in every second channel and a second fluid is arranged to flow in the remaining channels. For the channels to be leak-proof, the heat transfer plates 18 must be pressed against each other whereby the gaskets seal between the heat transfer plates. To this end, the plate heat exchanger 2 comprises a number of tightening means 20 arranged to press the end plates, 4 and 6, respectively, towards each other.

The first fluid enters and exits the plate heat exchanger 2 through an inlet 22 and an outlet 24, respectively. Similarly, the second fluid enters and exits the plate heat exchanger 2 through an inlet 26 and an outlet 28, respectively. The inlets 22, 26 and outlets 24, 28 are arranged on the same side of the plate heat exchanger. The inlets and outlets 22, 24, 26 and 28

communicate and are aligned with a respective one of the portholes 8, 10, 12 and 14 of the end plate 4. Thus, each of the fluids is fed through one of the inlets, one of the ports, every second one of the channels, another one of the ports and through one of the outlets.

The inlets and outlets each comprises a pipe provided with an annular flange extending around the pipe and radially outwards from an edge thereof. The pipe and the flange for the inlet 22 are indicated by reference numerals 22a and 22b, respectively, in Fig. 2.

To protect the end plate 4 from the fluids which otherwise could cause corrosion of the end plate 4 in the area of the portholes 8, 10, 12 and 14, the plate heat exchanger 2 further comprises four similar lining devices, each of the lining devices being arranged in a respective one of the port holes for lining it. The lining device arranged in the porthole 8 is indicated by reference numeral 30 and illustrated most clearly in Figs. 3-5.

The lining device 30 comprises a first part 32, a second part 34 and a tubular third part 36. The first and second parts 32 and 34 are similar and formed by stretch-forming of a sheet of sheet stainless steel. The first and second parts 32 and 34 each comprise a tubular inner portion 42 and 44, respectively, having a varying diameter as will be described in more detail later, and an outer portion 46 and 48, respectively, in the form of a flange extending radially outwardly from the respective tubular inner portion. The tubular inner and outer portions of the first part are integrally formed, just like the tubular inner and outer portions of the second part. The tubular third part 36, which has a constant diameter, is also formed of sheet stainless steel, formed and welded into a tube. The first, second and third parts 32, 34 and 36 have the same, essentially constant, wall-thickness t.

When the lining device 30 is mounted to the end plate 4, the tubular inner portions 42 and 44 of the first and second parts 32 and 34, respectively, extend inside the porthole 8 which is defined by a cylindrical inner wall 49 of the end plate. Further, the flange-shaped outer portion 46 extends on the outside O of the end plate 4 such that an inside of the flange-shaped outer portion 46 abuts the outside wall 7, while the flange-shaped outer portion 48 extends on the inside I of the end plate 4 such that an inside of the flange-shaped outer portion 48 abuts the inside wall 5 of the end plate 4. Further, the tubular third part 36 extends inside the porthole 8 and within the tubular inner portions 42 and 44 of the first and second parts 32 and 34. Arranged like this, the third part 36 engages with the tubular inner portions 42 and 44 of the first and second parts 32 and 34 so as to couple them and fix the lining device 30 to the end plate 4. More particularly, a first section 50 of the third part 36 overlaps an overlap section 52 of the tubular inner portion 42 (sections delimited by dashed lines L1 and L2 in Fig. 5) in a first overlap 54, while a second section 56 of the third part overlaps an overlap section 58 of the tubular inner portion 44 (sections delimited by dashed lines L3 and L4 in Fig. 5) in a second overlap 60. Thus, an outside 57 (Fig. 5) of the third part 36 faces an inside 59 (Fig. 4) of the tubular inner portion 42 within the first overlap 54, and an inside 61 (Fig. 4) of the tubular inner portion 44 within the second overlap 60. Within the first and second overlaps 54 and 60, a nominal inside diameter of the tubular inner portions 42 and 44 of the first and second parts 32 and 34 is essentially equal to an outside diameter of the third part 36 to enable a tight fit between the third part and each of the first and second parts.

To seal between the first, second and third parts 32, 34 and 36, respectively, and achieve a tight lining device 30 that fully protects the porthole 8 from fluid exposure, the lining device 30 further comprises a first sealing means 62 for sealing between the first and third parts 32 and 36, and a second sealing means 64 for sealing between the second and third parts 34 and 36. The first and second sealing means 62 and 64 are similar and formed as first and second annular gaskets, more particularly first and second rubber o-rings. To receive the first o-ring 62, the tubular inner portion 42 of the first part 32 is provided with an annular recess 66 extending within the overlap section 52 and giving the tubular inner portion 42 a locally increased diameter. Similarly, to receive the second o-ring 64, the tubular inner portion 44 of the second part 34 is provided with an annular recess 68 extending within the overlap section 58 and giving the tubular inner portion 44 a locally increased diameter.

Thus, when the lining device 30 is mounted to the end plate 4, the first o-ring 62 is arranged in the recess 66 so as to extend and seal between the first and third parts 32 and 36 within the first overlap 54, while the second o-ring 64 is arranged in the recess 68 so as to extend and seal between the second and third parts 34 and 36 within the second overlap 60.

For the lining device 30 to work properly, its parts and o-rings should be arranged in relation to each other and the end plate 4 as above described. To maintain this arrangement of the parts and o-rings of the lining device 30, the first part 32 comprises a first locking means 70 in the form of an annular first bulge on the inside of the tubular inner portion 42 of the first part 32, which first bulge is arranged outside the first overlap section 52 of the tubular inner portion 42 and close to the flange-shaped outer portion 46. The first bulge 70, having a height h, gives the tubular inner portion 42 a locally decreased inside diameter which is smaller than the outside diameter of the third part 36. Similarly, the second part 34 comprises a second locking means 72 in the form of an annular second bulge on the inside of the tubular inner portion 44 of the second part 34, which second bulge is arranged outside the second overlap section 58 of the tubular inner portion 44 and close to the flange-shaped outer portion 48. The second bulge 72, having a height h, gives the tubular inner portion 44 a locally decreased inside diameter which is smaller than the outside diameter of the third part 36. Further, the third part 36 comprises first and second locking means 74 and 76, respectively, in the form of annular opposing first and second edges and of the tubular third part.

Thus, as is clear from Fig. 5, when the lining device 30 is mounted to the end plate 4, the third part 36 is arranged between the bulges 70 and 72 of the first and second parts 32 and 34. The annular first and second edges 74 and 76, respectively, of the third part is arranged to engage with the bulges 70 and 72, respectively, to delimit displacement of the third part 36 in relation to the first and second parts 32 and 34 in a direction parallel to a longitudinal center axis X of the third part 36 and the assembled lining device 30 (Fig. 4). For an inside of the lining device 30 to be as even as possible, the height h of the bulges 70 and 72 is essentially equal to the wall thickness t of the third (and thus also the first and second) part 36 of the lining device.

Thus, the first, second and third parts 32, 34 and 36 of the lining device 30 are arranged to engage non-permanently with each other so as to enable simple, repeated and non-destructive assembly and disassembly of the lining device without the need for special tools or equipment. Typically, when the lining device 30 is to be mounted to the end plate 4, the o-rings 62 and 64 are arranged in the recesses 66 and 68 of the first and second parts 32 and 34, the third part 36 is pushed into the tubular inner portion 42 of the first part 32 so as to form the first overlap 54, the third part is inserted into the porthole 8 from the outside O of the end plate 4 until the flange-shaped outer portion 46 of the first part 32 contacts the outside wall 7 of the end plate, and the tubular inner portion 44 of the second part 34 is inserted into the porthole 8 from the inside I of the end plate 4 and pushed onto the third part until the flange-shaped outer portion 48 of the second part contacts the inside wall 5 of the end plate 4 so as to form the second overlap 60.

It should be said that the recesses 66 and 68, just like the bulges 70 and 72, besides for receiving the o-rings and limiting the relative movement of the first, second and third parts, respectively, also makes the lining device 30 more rigid and less prone to deformation, e.g. as a result of a high fluid pressure in the porthole 8.

A gasket (not illustrated) is arranged between the flange-shaped outer portion 48 of the second part 34 of the lining device 30 and the heat transfer plate arranged most adjacent to the end plate 4. Further, by means of fastening means not illustrated, the inlet 22 is fastened to the end plate 4 with a gasket (not illustrated) arranged between the flange 22b of the inlet 22 and the flange- shaped outer portion 46 of the first part 32 of the lining device 30.

The pipe and the flange for the inlet 22 are indicated by reference numerals 22a and 22b, respectively, in Fig. 2.

Fig. 6 illustrates a lining device 30' according to an alternative embodiment of the present invention. Here, the tubular third part 36' partly encloses the tubular inner portions 42' and 44' of the first and second parts 32' and 34', respectively, instead of the other way around as in the previously described embodiment. Further, the annular recesses 66' and 68' for receiving the annular gaskets 62' and 64' result in a locally decreased, instead of locally increased, diameter of the inner portions 42' and 44'. Here, a transition between the inner portions 42' and 44' and the outer portions 46' and 48' of the first and second parts 32' and 34' constitutes the first and second locking means 70' and 72', respectively, of the first and second parts, while the first and second locking means 74' and 76' of the third part 36' are constituted of the annular edges of the third part just like in the previously described embodiment.

Fig. 7 illustrates a lining device 30" according to yet another

embodiment of the present invention. Here, the third part 36" is arranged on the outside of the tubular inner portions 42" and 44" of the first and second parts 32" and 34", just like in Fig. 6. Further, the first sealing means 62" sealing between the first and third parts 32" and 36", respectively, and the second sealing means 64" sealing between the second and third parts 34" and 36", respectively, are not o-rings but annular gaskets provided with a respective annular groove 78" and 80" for receiving a respective inner edge 82" and 84" of the tubular inner portions 42" and 44" of the first and second parts 32" and 34". Thus, in the lining device 30", the gaskets 62" and 64" enclose the inner edges 82" and 84" of the tubular inner portions 42" and 44". Accordingly, the inner portions 42" and 44" need not be provided with gasket receiving recesses.

The above described embodiments of the present invention should only be seen as examples. A person skilled in the art realizes that the embodiments discussed can be varied and combined in a number of ways without deviating from the inventive conception.

As an example, in the above described embodiments, the gasket receiving recesses are comprised in the tubular inner portions of the first and second parts of the lining device. The gasket receiving recesses could instead be comprised in the third part of the lining device.

The lining devices described above are designed to have a circular cross section. Naturally, other designs of the lining device giving non-circular cross sections, e.g. an oval cross section, are conceivable.

The first and second parts of the lining device need not be equal like above but can have different designs. Further, the first, second and third parts need not have a constant and/or the same wall thickness. As an example, the gasket receiving recesses may be grooves milled in the first and second parts resulting in a varying wall thickness of the first and second parts and possibly a diameter not locally decreased/increased. The lining device can be used for other heat exchangers than gasketed plate heat exchangers, basically any heat exchanger comprising lining devices, for example permanently joined plate heat exchangers.

The first, second and third parts and the o-rings of the lining device need not be made of the materials given above but can be made of any suitable materials. The first, second and third parts may for example instead be made of titanium or aluminum, depending, for example, on the characteristics of the fluids to be fed through the lining device and the operating conditions.

The bulges of the first and second parts in between which the third part is arranged to extend, may have a height h not equal to the wall thickness of the first, second and third parts.

The lining device described above is arranged in the end plate 4 or the so-called frame plate. Naturally, the lining device could instead be arranged in the other end plate 6, the co-called pressure plate, depending on how the inlets and outlets of the heat exchanger are positioned .

Figs. 5 and 7 illustrate two different types of gasket solutions for the lining device according to the invention. Naturally, other gasket solutions are conceivable, for example solutions with gaskets having other cross sections than the ones illustrated herein. Also, other types of sealing means than gaskets are conceivable, such as sealants, adhesives or tapes fastened to, and covering, the joints between the third part and the first and second parts.

Furthermore, the lining device need not comprise the first and second sealing means. The first, second and third parts may instead be permanently connected by welding, brazing, gluing, etc.

The locking means of the lining device 30 comprise bulges and edges arranged to engage with each other to limit the relative movement of the first, second and third parts. As is clear form Fig. 5, the distance between the bulges is longer than the length of the third part which enables the third part to be displaced somewhat before one of the bulges comes in its way. Naturally, the distance between the bulges could instead be equal to the length of the third part so as to completely prevent displacement of the third part in relation to the first and second parts. Further, locking means of other types than bulges and edges may of course be used in the lining device according to the invention. As an example, the locking means of the first and second parts could each comprise a protrusion, and the locking means of the third part could comprise recesses, the protrusions being arranged to engage with a respective one of the recesses so as to limit or completely prevent movement of the third part in relation to the first and second parts. Also, it is also conceivable that only one of the first and second parts comprises a locking means, that the third part comprises one locking means only, and that said locking means are arranged to engage with each other to limit the displacement of the third part in relation to the first and second parts in, not only one direction like above, but in both directions.

The tubular inner portions of the first and second parts may be flared, i.e. have an innermost portion with a diameter differing from the nominal diameter to facilitate assembly of the lining device. If the third part is to be arranged on the outside of the inner portions of the first and second parts, the diameter of their innermost portions may be slightly smaller than the nominal diameter. Further, if the third part is to be arranged on the inside of the inner portions of the first and second parts, the diameter of their innermost portions may be slightly larger than the nominal diameter.

The above described lining devices are arranged to "clamp" the end plate between the outer portions of the first and second parts. Naturally, alternative/additional means, such as adhesive, for fixing the lining device to the end plate may be provided.

Finally, the first and second parts need not be integrally formed. For example, they may instead be composed of a pipe portion and a flange portion joined together, e.g. by welding.

It should be stressed that a description of details not relevant to the present invention has been omitted and that at least some of the figures are just schematic and not drawn according to scale. It should also be said the that some of the figures have been more simplified than others. Therefore, some components may be illustrated in one figure but left out or simplified in another figure.