WO2000014446A1

WO2000014446A1 - Compensator

Info

Publication number: WO2000014446A1
Application number: PCT/DK1999/000468
Authority: WO
Inventors: Benny Callesen
Original assignee: Ke-Burgmann A/S
Priority date: 1998-09-07
Filing date: 1999-09-03
Publication date: 2000-03-16
Also published as: AU5408799A

Abstract

The invention consists of a compensator comprising at least one elongated bending/bulb (2; 42) for the provision of a variable pipe length where the wall of the compensator has at least one wire mesh (12) and a fluoroplastic material joined together by melting of the fluoroplastic material. According to the invention, a particularly suitable compensator material is achieved for a variety of purposes while the wall properties provide a satisfactory combination of dimensional stability and flexibility.

Description

Compensator

Background of the invention

Flexible and heat resistant compensators with great flexibility in e.g. the longitudinal direction of the piping are known in many embodiments and a for wide range of applications. Within the chemical industry, they are e.g. specifically used as compensators and similar devices designed to absorb expansions in e.g. exhaust gas canals, among other things.

Compensators of e.g. corrosion-resistant steel are applied for particular purposes and are made by moulding in a matrix or a similar shaping tool.

The advantage of steel compensators is that they are relatively stable dimensionally.

Meanwhile, the disadvantage of these steel compensators is that they are relatively inflexible. Another disadvantage of the steel compensators is that they are relatively complex to manufacture since even minor variations of e.g. the diameter of the pipe, the number of bulbs, bulb length etc. require specific manufacturing equipment for each single variation. This, in turn, results in a quite limited range of products.

Compensators for other purposes may also be made of e.g. laminated wire mesh material. A compensator reinforced with a woven material such as aramid or mineral fibres is known from DE-Al-38 20 922. The compensator is moreover coated with an elastomeric material. However, such elastomer coating tends to develop cracks in the surface. These cracks increase in the depth as the compensator is used and can eventually result in an exposure of the wire mesh leaving the wire mesh exposed to e.g. corrosion. From DE-A1-196 33 158 a steel compensator coated with a protective layer and a method of manufacture of such is known. The advantage of these compensators is that they possess the necessary flexibility in relation to e.g. mechanical travel between the mounting ends. However, one disadvantage of this type of compensator is that the dimensional stability is not quite as good as that of the steel compensator mentioned above. This may e.g. result in the piping collapsing by negative pressure.

Massive PTFE compensators are also known from other application. These compensators are made by turning massive blocks of Teflon hollow resulting in a significant waste of material following from that process.

The object of the invention is to create a dimensionally stable, chemically resistant and flexible type of piping that may be manufactured by random sectional designs in a simple manner with only a limited use of material.

The invention

The invention consists of a compensator comprising at least one elongated bend/bulb for the provision of a variable pipe geometry characterized in that the wall of the compensator comprises at least one wire net and a fluoroplastic material joined together by melting of the fluoroplastic material.

According to the invention, it is possible to create individually tailored compensator material for a variety of purposes that offers wall properties with a satisfactory combination of dimensional stability and flexibility. This applies irrespective of whether the material consists of one or more layers.

The improved resistance of the interconnected material is due to the use of fluoroplastic laminate which is melted through the wire mesh so that each single wire is essentially fixed by surrounding fluoroplastic laminate.

Another and quite significant advantage of the invention is that e.g. steel, wire mesh, elastomer compensators etc. may be lined with a pipe wall, according to the invention. The invention also results in the elongation bend of the material being provided with a permanent and desired deformation so that the allocation of applied movements may be carried out as desired.

Previously, it has been necessary to line e.g. steel pipes with loosely applied more or less dimensionally stable compensators whereas it is now possible to line e.g. a steel compensator with a wall, according to the invention.

In this connection, it should be kept in mind that the elongation bends will follow the inner abutting surface making the mechanical strain properties of the compensator homogenous.

According to the invention, a compensator is a piping section that may be regarded as an expansion element. Another commercially used expression for such an element is bellows. The compensator is capable of absorbing a shifting whether the issue is one of shortening, elongation or an angle change.

Another advantage of a compensator according to the invention, is that it is capable of resisting all media and may therefore also be used for liquid purposes.

By, as specified in claim 1, letting the wall of the compensator consist of at least two layers of film that have been melted together so that the wire mesh is fixed between these, it is possible to obtain a particularly advantageous embodiment according to the invention since an actual lamination of the two films results in the wire mesh being fixed in the occurred pockets so that the actual mutual fixation of the wire mesh and the film is obtained in a simple and particularly functional manner. Thus, the fixation of the wire mesh is not solely determined by the mutual ability of the wire mesh and the fluoroplastic material to connect but more accurately by the ability of the fluoroplastic material itself to connect. In this connection, it should also be noted that the non-homogenous flexibility of the wire mesh makes it possible to fix the fluoroplastic material through the wire mesh. Non-homogenous flexibility means that the wire mesh forms a pitted penetrable surface.

Apart from that, it should also be noted that the fixing of the wire mesh in the plastic pockets creates solidity and resistance towards mechanical stress and deformation as such a change may not necessarily result in the fixing being completely destroyed. On the contrary, the formation of the pockets has shown that certain applications have a tendency to slip into the pockets so that a part of the mechanical stress is absorbed by a mutual relative movement between the wire and the plastic material.

Also note that the wall material, whether a mutual movement is present or not, possesses the ability to absorb mechanical deformations since such deformations are primarily absorbed by a mutual shifting of the wires and in the elastic mounting ends arising between the wires. A significant advantage of this is that these deformations are not necessarily permanent.

By, as specified in claim 2, letting the fluoroplastic material comprise at least one melted film, it is possible to achieve an advantageous embodiment since the handling and manufacture of a pipe wall based on film material in relation to a wire mesh is fairly simple in relation to e.g. automated manufacturing processes.

By, as specified in claim 3, letting the wire mesh consist of metal wires, it is possible to obtain a particularly advantageous embodiment, according to the invention, since the use of metal wires in particular provides e.g. a good combination of dimensional stability and flexibility in the total product.

Thus, the wire mesh provides the compensator with dimensionally stable properties suited for as well permanent as non-permanent deformations. This may e.g. result in the compensators being manufactured and moulded individually. By, as specified in claim 4, orientating the wires of the wire mesh in at least two directions at a given angle or given angles where all wires are angular in relation to the axial and/or lateral direction of the pipe, it is possible to obtain an advantage according to the invention, since an angling of the wires results in the compensators being capable of providing a shifting in the longitudinal direction by minimal curving of the metal wires. This is significant in relation to the manufacture of the individual mould of the compensator as the required moulding properties may be minimized. In addition, it is also a logical consequence that significant deformations of the individual metal wires should be minimized in order to prevent the wires from breaking.

By, as specified in claim 5, directing the wires of the wire mesh at an angle of approx. +/- 45° in relation to the longitudinal direction of the compensator, it is possible to obtain a particularly advantageous embodiment that is also quite capable of absorbing e.g. shortenings, elongations or angle changes.

In this connection, it should be noted that the angles between the wire directions may be adjusted to the actual desired piping properties.

By, as specified in claim 6, welding the pipe in the longitudinal direction of the compensator, it is possible to obtain a simple and advantageous closure of the circumference of the pipe which has proven resistant to even extensive pressure and high temperatures.

By, as specified in claim 7, letting the fluoroplastic material consist of PTFE, the material is quite attractive both in regard to properties and price.

The invention also relates to a compensator that may e.g. be manufactured by traditional materials such as steel, fabrics or elastomers comprising at least one elongation bending allowing for a variable pipe length characterized in that the steel compensator comprises at least one additional wall that comprises at least one wire mesh and a fluoroplastic material mutually joined by melting of the fluoroplastic material.

It is implicit that the additional wall may constitute any layer in the total piping wall. A specific example of such a layering may be a steel compensator where the additional wall forms an inner lining of the pipe.

Such a compensator may thus, according to the invention, be lined with a dimensionally stable chemically inert material which would be a distinct advantage for e.g. a steel compensator.

The invention also relates to a compensator comprising at least one elongation bending/bulb for the provisions of a variable compensator length characterized in that the compensator wall comprises at least one wire mesh and a fluoroplastic material mutually connected by melting of the fluoroplastic material.

In this manner, a unique advantage is obtained since the issue of tailored application has lacked a technical solution in association with a compensator and its application environment for a long time.

In this connection, it should be understood that a compensator may be exposed to extensive pressure and high temperatures just as the speed of the exhaust gas may easily exceed 100 km/h. All these stress factors must be absorbed by the compensator whilst also absorbing the powerful longitudinal displacements. Thus, the invention provides a special synergy in relation to compensators.

By, as specified in claim 10, manufacturing the pipe wall of the compensator in accordance with the following steps:

- lamination of at least two fluoroplastic films in such a manner that at least one wire mesh is fixed between these films, shaping of a pipe or a given desired geometric shape of the laminated pipe wall "welding" of the pipe or the given matrix for obtaining a closed circumference embossing of the elongation bendings/bulbs by means of mechanical deformation tools.

By, as specified in claim 11 , manufacturing the elongation bendings/bulbs by means of corresponding rotating pressure discs providing a rotating controllable pressing around the circumference of the pipe or another given geometric shape, it is possible to obtain a particularly advantageous manufacture of the finished version of the desired pipe. The method is thus flexible and may be implemented by means of a device that is not unnecessarily user-specific. According to the invention, the method may be carried out by a device that does not require replacement of deformation tools if the pipe diameter or cross section geometry of the pipe is altered. The concrete result is that the manufacture a specific matrix for each pipe becomes superfluous.

In this connection, it should be mentioned that more traditional manufacturing processes may be used, if so desired.

Figures In the following, the invention will be described with reference to the figures where

Figure 1 shows a longitudinal section of a compensator according to the invention Figure 2 shows the material layers in a pipe wall

Figure 3 shows the initial stage of a compensator according to the invention Figure 4 shows the final compensator and

Figure 5 shows how the compensator is shaped by means of the cylinder shown in figure 3

Embodiment Figure 1 shows an example of an embodiment according to the invention. The shown pipe section 1 , illustrated by a longitudinal cross-section view made from two layers of PTFE films that have been laminated around wire mesh of wires 2 in such a manner that the pipe, as shown in the depicted embodiment, basically comprises one PTFE pipe wall 3 with integrated metal wires 2. The shown wires may e.g. be of corrosion resistant stainless steel. It is implicit that the degree of lamination determines to how strong the connection between the two PTFE films is and to which degree the welded films will appear as a monolithic pipe wall.

The shown pipe section comprises a number of elongation bendings or bulbs 4 whereby the pipe section is provided with mechanical properties allowing the pipe to be elongated or shortened in the longitudinal direction of the pipe by only mechanical stress on e.g. the end fixings of the pipe section 1.

According to the shown embodiment, the metal wires 2 have been completely included in the pipe wall 3 resulting in the fact that e.g. chemical influence will be induced exclusively around PTFE which is perceived to be mechanically and chemically inert in many relations.

According to the invention, the shown pipe section 1 may be manufactured with the required number of bulbs 4 just as the cross section of the pipe section 1 may be adjusted to the actual application. This means that e.g. exhaust gas canals with square cross sections may be attached to the compensator without the use of adapters.

The shown pipe section may also be incorporated in a steel compensator (not shown) or in other types of compensators.

According to the invention, the pipe section offers a particularly advantageous combination of dimensional stability and flexibility.

Figures 2 to 4 show how a compensator could be manufactured in an advantageous manner, according to the invention. It is implicit and apparent to a skilled person that the compensators, according to the invention, may be manufactured in various other ways than the one described below.

Initially, a laminate is manufactured consisting of an upper layer of PTFE film 11, an intermediate wire mesh 12 and a lower layer PTFE film 13.

The layers of laminate 11, 12 and 13 are laminated in a known manner and subjected to high pressure and temperatures so that the films 11 and 13 are melted through the wire mesh 12. Subsequent to the lamination, the wire mesh is contained in and fixed between the films 11, 13.

In addition, it should be noted that the wires 14, 15 of the wire mesh 12 are in mutual angular positions of 90° and +/- 45° in relation to the direction of the laminate that will subsequently constitute the longitudinal direction of the compensator.

It is implicit that other angles may be used.

This condition provides the resulting compensator with particularly advantageous properties since the integrated wire offers minimal resistance against expansions in the longitudinal direction of the compensator irrespective of whether the expansions are shortenings or elongations. The reason for this is also to be found in the fact that the angular configuration of the wire mesh in relation to both the longitudinal and widthwise direction has the effect that instead of bending, the mutual angles between all crossed wires are changed without any significant friction or bending.

This fact is important in connection with the possibility of subsequent changes of the shape of the desired compensator.

Figure 3 shows an initial stage of a compensator, according to the invention, since the laminate manufactured in accordance with figure 2 is shaped as a cylinder 31 and welded in the longitudinal direction of the cylinder 32. It is implicit that the cross sections of a compensator, according to the invention, do not necessarily have to be circular but may also feature other cross sections such as rectangular ones.

Figure 4 shoes how a final compensator 41, according to the invention, has been designed with bulbs 42. The bulbs 42 are shaped in the cylinder pipe 31 as shown in figure 3 by the use of an appropriate mechanical deformation.

Figure 5 shows how a cylinder form 51 may be made with a bulb 52, according to an advantageous embodiment of the invention.

As shown in fig. 3, the cylinder is designed by the use of three cooperating discs 53, 54 and 55. The discs 53 and 54 rotate around a rotation axis 56 whilst the disc 55 rotate around an axis 57 just as the pipe 51 rotates around its longitudinal axis.

According to the shown embodiment of the invention, each bulb 52 is manufactured by rotating the pipe 51 the discs 53 and 54 and 55 so that these gradually manufacture the individual bulb 52 after one or preferably more rotations of the pipe 51. The movement of the discs 53, 54 may possibly be supplemented by a cross movement in the longitudinal direction of the pipe so that these discs, subsequent to the number of rotations of the pipe such as 5, move toward each other whereby the deformation of the pipe is carried out as gently as possible.

It is apparent from the shown drawing that the shaping parts of the tool are universal in the sense that the discs may in principle be used for any cross section contrary to e.g. matrixes specifically designed to a particular pipe.

It is also apparent that the bulb form; its width and height and the number of bulbs 52 per longitudinal unit of the pipe 51, according to the shown example, may be fitted by adjusting the vertical and horizontal movements of the discs. According to the invention, it is also possible to routinely manufacture pipe sections with any number of bulbs by using the same manufacturing tool.

Claims

Patent claims:

1. A compensator comprising at least one elongation bending for provision of a variable pipe length c h a r a c t e r i z e d i n t h a t the wall of the compensator comprises at least one wire mesh (12) and a fluoroplastic material joined together, and that the wall of the compensator has been constructed by at least two layers of fluoroplastic material laminated together in such a manner that the wire mesh (12) is fixed between these layers.

2. A compensator, in accordance with claim 1, characterized in that the fluoroplastic material comprises at least one layer of melted film.

3. A compensator, in accordance with claim 1 or 2, characterized in that the wire mesh (12) consists of metal wires (14,15).

4. A compensator, in accordance with claims 1 to 3, characterized in that the wires (14,15) of the wire mesh (12) are orientated in at least two directions at a given angle or given angles where all wires are at an angular position in relation to the axial or lateral direction of the pipe.

5. A compensator, in accordance with claims 1 to 4, characterized in that the wires (14,15) of the wire mesh (12) are orientated at an angle of approx. +/- 45┬░ in relation to the longitudinal direction of the pipe.

6. A compensator, in accordance with claims 1 to 5, characterized in that the pipe is welded together in the longitudinal direction of the compensator.

7. A compensator, in accordance with claims 1 to 6, characterized in that the fluoroplastic material is PTFE.

8. A compensator comprising at least one elongation bending (2) for the provision of a variable pipe length characterized in that the compensator comprises at least one additional wall comprising at least one wire mesh (12) and a fluoroplastic material joined together by melting of the fluoroplastic material.

9. A compensator comprising at least one elongation bending for the provision of a variable compensator length characterized in that the wall of the compensator comprises at least one wire mesh (12) and a fluoroplastic material joined together by melting of the fluoroplastic material.

10. A method of manufacturing a compensator, in accordance with claims 1 to 9, characterized in that the pipe wall of the compensator is manufactured in accordance with the following steps:

- lamination of at least two fluoroplastic materials (11, 13) so that at least one wire mesh (12) is fixed between these materials shaping of a pipe (41) or a given desired form of the laminated pipe wall "welding" of the pipe (1) or a given form for obtaining a closed circumference embossing of the elongation bendings/bulbs (2) by mechanical deformation tools.

11. A method of manufacturing a compensator, in accordance with claim 10, characterized in that the elongation bendings (2; 42) are manufactured by corresponding rotating pressure discs (53, 54; 55) that produce a rotating controllable pressure around the circumference of the pipe (51) or the circumference of any given desired form.