WO1982001759A1

WO1982001759A1 - Axial compensator

Info

Publication number: WO1982001759A1
Application number: PCT/DK1981/000099
Authority: WO
Inventors: Kompensatorfab As Bredan
Original assignee: Bredahl Henning
Priority date: 1980-11-10
Filing date: 1981-11-10
Publication date: 1982-05-27
Also published as: DE3152521T1; GB2100820A; DK147189B; NL8120426A; SE8203829L; FI822264L; FI822264A0; NO822068L; SE8203829D0; GB2100820B; EP0064530A1; DK476980A

Abstract

Des changements de longueur d'un tuyau de chauffage d'un secteur qui resultent des changements de temperature sont absorbes en introduisant des compensateurs axiaux, ces compensateurs etant pourvus d'un soufflet metallique flexible (1) fixe de maniere etanche au gaz a chacune de ses pieces tubulaires (3, 4) a l'interieur du compensateur. Les variations de longueur qui se produisent sont compensees par le soufflet metallique. Cette construction permet d'avoir un compensateur completement ferme, empechant ainsi l'entree d'eau, de vapeur et de corps etrangers entre les extremites des tubes, et assure ainsi un fonctionnement sans perturbation du soufflet. En formant les tubes (3, 4) de telle maniere a ce qu'ils jouent le role d'un guide telescopique, on obtient une rigidite optimale et par consequent la protection du soufflet. Le soufflet (1) est protege exterieurement par un carter consistant en un cylindre (10) qui s'etend entre deux brides (7, 8), renfermant totalement le soufflet. En outre, le compensateur peut etre pourvu d'une paire de rails (9) ayant un engagement coulissant avec des evidements dans un guide (11), ce guide etant fixe au carter cylindrique (10). Ceci evite les torsions du soufflet pendant le travail d'installation, lorsque le compensateur est tourne pour permettre d'avoir acces et souder entre le compensateur et le tuyau de chauffage.Changes in the length of a district heating pipe which result from changes in temperature are absorbed by introducing axial compensators, these compensators being provided with a flexible metal bellows (1) fixed in a gas-tight manner to each of its tubular parts (3, 4) inside the compensator. The variations in length that occur are compensated for by the metal bellows. This construction makes it possible to have a completely closed compensator, thus preventing the entry of water, steam and foreign bodies between the ends of the tubes, and thus ensures operation without disturbance of the bellows. By forming the tubes (3, 4) in such a way that they play the role of a telescopic guide, optimal rigidity is obtained and consequently the protection of the bellows. The bellows (1) is externally protected by a casing consisting of a cylinder (10) which extends between two flanges (7, 8), completely enclosing the bellows. In addition, the compensator can be provided with a pair of rails (9) having a sliding engagement with recesses in a guide (11), this guide being fixed to the cylindrical casing (10). This prevents twisting of the bellows during installation work, when the compensator is rotated to allow access and weld between the compensator and the heating pipe.

Description

AXIAL COMPENSATOR.

This invention concerns an axial compensator for insertion into a pipeline, such as a district heating pipeline, and comprising a flexible metal bellows, each end of which is connected to its corresponding part of the pipeline.

Compensators of this kind find particular application in district heating pipelines, where they can absorb the movements in the pipelines which arise as a result of temperature changes. The pipeline system is thus safegurded against stresses , in that longitudinal changes can be absorbed by the flexible bellows.

An axial compensator of this type is known from English Patent No. 898,383. It consists of an internal tube, the centre of which is provided with an external flange , and to which one end of the bellows is connected. The other end of the bellows is secured to a ring which can be moved axially external to the tube. To the ring is welded an external pipe which extends over the bellows, and which via a guide for the absorption of torsion extends out over the tube. The two ends of the pipe can be welded to the pipeline during assembly.

This known axial compensator is, however, inexpedient, the reason being that the internal side of the bellows stands in free connection with the surroundings. There is thus the possibility of water and dirt collecting inside the bellows, hereby rendering the bellows incapable of being compressed. Moreover, a great risk of damage to the bellows will arise when foreign bodies collect between the folds of the bellows. To prevent torsion of the bellows, the compensator is provided, as mentioned above, with a guide which is disposed as an extension of the bellows. This gives a greater construction length, which is unfortunate, as this in turn demands more room for assembly. Furthermore, since the moment of effect becomes greater, the compensator is also further loaded.

It is the object of the present invention to overcome the disadvantages of the known compensators, and this is achieved when the one end of the bellows is connected in a gas-tight manner, with the outer side of a tube which is secured to the one pipe end, said tube being capable of gliding along the outside of the other pipe end, while the other end of the bellows is connected in a gas-tight manner with said other pipe. The construction achieved herewith is simple and uncomplicated and provides the possibility of complete protection of the bellows, in that they are exposed to the influences of water or steam only on their inner side. The outside of the bellows can easily be protected by means of an external casing which extends from the one end to the other end of the bellows. The construction length of the compensator, moreover, is made very short, since it needs only to comprise the bellows.

By securing the ends of the bellows to flanges in the manner described in claim 2, a compact and simple construction is achieved, and which is easy to produce and assemble.

Finally, and as presented in claim 3, it is expedient to provide the compensator with a guide which runs externally on the one pipe, and which extends from the one flange. This is an effective and operationally reliable guide arrangement, in that any possible foreign matter will be pushed away from the rail. Furthermore, there is thus ensured good absorption of forces not only in the longitudinal direction, but also of torsional forces which arise particularly during installation.

The invention will now be described more closely with reference to the accompanying drawings, where

Fig. 1 is a cross-sectional drawing showing the compensator in its extended and compressed position respectively, seen in the direction of the line I - I in fig. 2, and

Fig. 2 shows the compensator seen from the end in the direction of line II - II in fig. 1.

Fig. 1 shows one embodiment of the compensator in accordance with the invention. The upper half of the drawing shows the compensator in its fully extended position, while the ghost, lines of the lower half of the drawing show the compensator in its compressed position.

The one end of the district heating pipe 13 is shown to the left of the drawing, and its other end 12 to the right of the drawing. The axial compensator is inserted between these ends.

The left-hand part of the compensator comprises a connection pipe 6, said pipe being welded to the left-hand pipeline 13 and having mainly the same diameter as said pipeline. To the pipe 6 is welded a ring-shaped flange 7 having the same internal diameter. The inner side of flange 7 is welded to a tube 3 which can slide externally along the right-hand tube piece 4 of the compensator. The left-hand end 2 of the bellows is also secured in a gas-tight manner to the flange 7, and a casing 10, in the form of a cylinder, is secured outermost. At the right-hand end of cylinder 10 is secured a guide 11, said guide 11 being in the form of a ring having two recesses in its inside surface.

The right-hand part of the compensator comprises the tube piece 4, this tube piece being welded to the end 12 of the right-hand district heating pipe. The tube piece 4 also has essentially the same diameter as the pipe 12. To the tube piece 4 is welded a ring-shaped flange 8, to which the right-hand end 5 of the bellows 1 is secured in a gas-tight manner.

In addition, up to and extending from flange 8 to the right on tube piece 4 are disposed a pair of diametrically opposite rails 9, said rails extending axially. These rails 9 cooperate with the above-mentioned recesses in the guide 11, so that torsional influences will be taken up by said guide. The guide and the recesses can be seen more clearly in fig. 2.

During operation, and thus when the pipelines are heated up, there will arise, among other things, a thermal expansion in the longitudinal direction, for example to that position illustrated by the ghost lines in the lower half of fig. 1. The bellows are partly compressed by the telescopic action of the tube 3 and tube piece 4, Moreover, it will be seen from the drawing that the compensator can be further compressed until the tube piece 4 lies up against the flange 7. in other words, the working length of the compensator is the distance between the flange 7 and the end of the tube piece 4. During operation, the compensator will hunt in step with the temperature variation. This spares the district heating pipelines, in that during operation they are not exposed to stresses caused by the expansion of materials.

In the case of an increase in temperature, or mechanical compression of the compensator, the end of the tube piece 4 will abut the flange 7, and thus the axial thrust forces are transferred direct through the. tube parts without the bellows being loaded. Moreover, the bellows are of such dimensions to enable them to be compressed an even further amount, whereby they maintain their bellows function in the event of any subsequent, expansion.

Conversely, for example in the event of a drop in temperature resulting in tension in the pipeline, the casing 10 and the guide 11 will abut the flange 8. The tensional forces are thus transferred through these parts, and the bellows remain unloaded. The bellows are so:..dimensioned as to enable them to be extended an even further amount, and thus with any subsequent compression they can resume their normal bellows function.

Thus, since the compensator at these loads ccmprises a firm part of the pipeline network without compensator function, some of the so-called fixed points can be avoided, i. e., anchoring of the pipeline network to the ground by means of castings. This results in considerable financial savings when establishing the network. The construction provides an operationally reliable and stable compensator, capable of working completely without supervision. Moreover, the outside of the bellows is completely protected against impurities and other harmful influences, and thus they can function freely without any risk of damage. Furthermore, the flow of the medium through the compensator is optimized, in that its constant cross-section does not give rise to any appreciable resistance. Neither does the compensator give rise to any noise in the pipeline.

In addition, since it is accurately controlled in the logitudinal direction as well tortionally, the compensator is very robust. This is due to the long guide formed by the telescopic action of -the tubes 3 and 4, and partly to the precise control provided by the rails 9 and the recesses in the guide 11. The compensator is therefore easier to install, the reason being that it is not deformed by heavy-handed treatment during the installation work. It is therefore quicker and thus more economical in its manufacture, installation and operation, than other known compensators. Furthermore, any possible leakage in the bellows will not present any danger to anyone who might be in the vicinity, the reason being that the water or the steam will seep out along the guide.

Claims

C L A I M S

1. Axial compensator for insertion into a pipeline, such as a district heating pipeline, and comprising a flexible metal bellows, each end of which is connected to its part of the pipeline, c h a r a c t e r i z e d in, that the one end (2) of the bellows (1) is connected in a gas-tight manner with the outside of a tube (3), said tube (3) being secured to the one pipe end (6) and being capable of sliding along and around a second tube piece (4), and in that the other end (5) of the bellows (1) is connected in a gas-tight manner with said second tube piece (4).

2. Axial compensator according to claim 1, c h a r a c t e r i z e d in, that the ends (2, 5) of the bellows are secured to each its flange (7, 8), which flanges are secured in a gas-tight manner to the pipe end (6) and the tube piece (4) respectively.

3. Axial compensator according to claims 1 and 2, c h a r a c t e r i z e d in, that from the one flange (8) and external to tube piece (4) there is provided at least one axially extending rail (9), and and that from the pipe end (6), preferably from the flange (7), a casing (10) is provided which extends externally to the bellows (1) up to the flange (8), and which at its opposite end is provided with a guide (11) having a recess which cooperates in a sliding manner with the rail (9).