GB2241035A

GB2241035A - Shrink fit cryogenic conduit connection system with bellows

Info

Publication number: GB2241035A
Application number: GB9103396A
Authority: GB
Inventors: Guenther Blumenberg; Klaus Schippl
Original assignee: Kabelmetal Electro GmbH
Current assignee: Kabelmetal Electro GmbH
Priority date: 1990-02-20
Filing date: 1991-02-19
Publication date: 1991-08-21
Also published as: DE4005303A1; GB9103396D0

Abstract

A plug-in connection for cryogenic conduits is configured as a male/female connection, When the conduit is taken into service, the female part (6) which has a higher coefficient of expansion shrinks onto the male part (14) consisting of invar steel, and seals the connection. The male part (13, 14, 15) is constructed as a part that can be slipped or screwed onto the end (12) of the cryogenic conduit, and consists of a first (13) and a second (14) sleeve, which are mutually connected by means of a bellows (19). The sleeves (13, 14) and the bellows (19) are seated on a support pipe (15). <IMAGE>

Description

1 1

- 1 DESCRIPTION CONDUIT CONNECTION SYSTEM

The invention relates to a plug-in connection f or conduit pipes for transporting intensely cooled media or a terminal connection for fittings, unions, etc. on such pipes, in the case of which the parts to be connected are plugged into one another in the manner of a male/female connection, and the seal of the male part with respect to the female part is achieved when the male part consists of a metal having a low coefficient of thermal expansion and the f emale part consists of a metal having a high coefficient of thermal expansion.

Such a plug-in connection is known f rom German Utility Model 8,432,062. The plug-in connection does not become ef f ective as a seal until the intensely cooled medium flows through the conduit pipe and also the plugin connection. When the female part cools, it shrinks more strongly than the male part, and shrinks onto the male part. After the conduit has been taken out of service, the parts heat up, the shrink fit works loose and the plug-in connection can be released at room temperature. Since the heat is incident from the outside. the female part will heat up earlier and expand more rapidly and lift away from the male part.

A disadvantage of this known plug-in connection is to be seen in that exchangeability of the male or female parts is not provided, without the vacuum chamber of the insulating structure required for the purpose of intense cooling being disconnected or opened. A further disadvantage is that during the cooling phase, but also during the heating phase, stresses can build up inside the plug-in connection in the direction of the longitudinal axis, which can have a damaging effect on the welded joints.

It is therefore the object of the invention to improve the known plug-in connection to the effect that during the heating phase and cooling phase no or only non-damaging longitudinal stresses are produced, and that both of the male part and the f emale part can be exchanged without the vacuum chamber of the intensely cooled conduit being disconnected.

This object is achieved when the male part is constructed as a part that is slipped or screwed onto the end of the conduit pipe and consists of a f irst and a second tubular sleeve, which are mutually connected by means of a bellows, and the sleeves and the bellows are seated on a support pipe.

Apart from the advantages arising directly from the setting of the object, the advantage further arises that the male part and f emale part can be plugged into one another in any direction, i.e. horizontally or vertically.

An advantageous embodiment of the invention provides that the f irst sleeve, which is slipped onto the end of the conduit pipe, is welded to the support pipe. This produces a male part that lends itself to manipulation and can be easily exchanged.

The second sleeve has a larger inner diameter than the outer diameter of the support pipe. Although the f irst and second sleeve are mutually connected via the bellows, it is sensible to create a limitation of the longitudinal axial movement of the second sleeve, in order to relieve the bellows. For this purpose, a flange is provided at the end of the support pipe according to a further concept of the invention.

It is expedient for the first sleeve to be welded to the end of the conduit pipe, if the f irst sleeve consists of a material which has the same coefficient of thermal expansion as the part on which it is seated. If the part on which the first sleeve is seated consists. for example, of a material having a low coefficient of thermal expansion, welding is not required and also not sensible, since the seal comes about from the first sleeve shrinking onto the part. The mechanical connection that is required for manipulation at room temperature is then effected, for example, by screwing the part to the first sleeve.

Moreover. the plug-in connection according to the invention is characterized in that at one end the tubular @z -1 is f emale part has an expansion of its inner diameter and is screwed by means of this expansion onto a bush which is screwed onto the inner pipe of the conduit pipe and is welded to the inner pipe. Here. too. the screwing serves the.mechanical connection of the female part to the end of the conduit pipe.

The invention is explained in more detail with reference to the illustrative embodiment represented diagrammatically in the figure.

A representation is given of a plug-in connection for the ends of two conduit pipes, which consists of an inner pipe, a further pipe concentrically surrounding the inner pipe, and an evacuated annular chamber. However. the invention is also applicable to conduit pipes having further concentric layers, for example so-called quadruple conduits.

The inner pipe 1 of the conduit pipe is a helically corrugated pipe made of high-quality steel, on the end of which a screw-in bush 2 is screwed on. The end of the inner pipe 1 is formed against the chamfer 3 of the screw-in bush 2, and welded there. The screw-in bush 2 likewise consists of high-quality steel. A pipe extension piece 4, which connects the outer pipe (not further represented), which is normally likewise corrugated, of the conduit pipe to the screw-in bush 2, is welded to the screw-in bush 2 on the circumferential surface thereof. The chamber 5 between the inner pipe 1 and the extension piece 4 is evacuated. This evacuated annular chamber 5 extends over the entire length of the conduit pipe.

The female part 6 is screwed onto the screw-in bush 2, to be precise by means of the thread 7. Mounted between the screw-in bush 2 and the f emale part 6 is a seal 8. for example a copper ring, a graphite seal etc. An end thus prepared of a conduit pipe can be connected detachably to a similarly prepared conduit pipe, or joined to a consuming device via a short plain pipe connection. Represented in the left-hand half of the f igure is the end of a conduit pipe, which consists of an inner pipe 9 and an outer pipe 10. Situated between is the pipes is a vacuum chamber 11, which is sealed by an annular bush 12, which is welded to the inner pipe 9 and to the outer pipe 10. The end of the conduit pipe is connected to a male part, which consists of a first sleeve 13 and a second sleeve 14. Both sleeves 13 and 14 are seated on a support pipe 15, which is welded at the end face to the first sleeve 13. and on which the second sleeve 14 is arranged capable of being displaced longitudinally. A f lange 16 on the end of the pipe piece 15 serves to limit the longitudinal displaceability. The f irst and the second sleeve 13 and 14 are connected by means of a bellows 19, the ends of which are welded to the first and second sleeve 13 and 14.

The first sleeve 13 embraces the annular bush 12r and is either screwed onto or welded to the latter.

As in the prior art, the second sleeve 14 consists of invar steel, and the female part encasing it in the operational state preferably consists of a copper alloy such as brass or bronze. It is advantageous for the first sleeve 13 likewise to consist of the same material as the female part 6, and the annular bush 12 to consist likewise of invar steel. The screw-in bush 2 likewise consists of invar steel.

When a pipeline provided with a plug-in connection as represented is taken into service for transporting intensely cooled media, warm gas firstly flows through the conduit and partly emerges through the annular clearance, still open, of the plug-in connection. The more the gas cools through mixing with the medium, the smaller the clearance cross-sections become as a consequence of the different coefficients of thermal expansion of invar steel and the copper alloy.

The thin-walled lips 17 and 18, especially, cool rapidly, consequently shrink down onto the annular bush 12 or the screw-in bush 2 and seal these clear-ances. After a relatively short time. the female part 6 is also shrunk down onto the second sleeve 14, so that it is no longer possible for medium to emerge from the plug-in connection.

1 1 The essential advantage of the invention is to be seen in that the entire male part can be screwed or welded as a unit to the end of the conduit pipe and can likewise be released once again without destroying the vacuum in the annular chamber 11. A precise insertion of the coupling is possible through the bellows 19 and the support pipe 15. Overexpansion and tearing of the bellows 19 is avoided by the f lange 16. The bellows 19 bridge small axial inaccuracies.

It will be understood that the Invention has been described above purely by way of example, and that various modifications of detail can be made within the ambit of the Invention.

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Claims

1. A conduit connection system, suitable for use in connecting conduit pipes for transporting intensely cooled media, or in providing a terminal connection between fittings, unions and other terminations and such pipes; the parts to be connected being plugged into one another in the manner of a male-and-female connection, and the seal of the male part with respect to the female part being achieved by the use of a male part composed of a metal having a lower coefficient of thermal expansion and a female part composed of a metal having a higher coefficient of thermal expansion; wherein the male part takes the form of a part that is slipped or screwed on to the end of a conduit pipe and comprises a first and a second tubular sleeve, which sleeves are mutually connected by means of a bellows, 0. r ú and the sleeves and the bellows carried by a support pipe.

2. A conduit connection system according to claim 1, wherein the first sleeve is slipped on to the end of the conduit pipe, and is welded to the support pipe.

3. A conduit connection system according to claim 1 or 2, wherein, at its free end, the support pipe has a flange that limits the axial movement of the second sleeve.

4. A conduit connection system according to claim 1, 2 or 3, wherein the first sleeve is welded to the end of the conduit pipe.

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5. A conduit connection system according to claim 1, 2, 3 or 4, wherein, at one end, the female part has an expansion of its inner diameter, being screwed by means of this expansion on to a bush which is screwed on to the inner pipe of a conduit pipe and which is welded to the inner pipe.

6. A conduit connection system according to claim 1, substantially as described with reference to the accompanying drawing.

Published 1991 at'Me Patent Office, State House. 66/71 High Holborn. LondonWC I R 4TP. Further copies may be obtained from Sales Branch, Unit 6. Nine Mile Point Cwrnfelinfach, Cross Keys. Newport- NP1 7HZ. Printed by Multiplex techniques ltd. St Mary Cray, Kent.