GB2198204A

GB2198204A - Pipe connection

Info

Publication number: GB2198204A
Application number: GB08629220A
Authority: GB
Inventors: Bryan Leslie Belcher
Original assignee: Rolls Royce PLC
Current assignee: Rolls Royce PLC
Priority date: 1986-12-06
Filing date: 1986-12-06
Publication date: 1988-06-08
Also published as: GB8629220D0

Abstract

A pipe connection between a first pipe (10) and a second pipe (16) in which the first pipe (10) is penetrated by the second pipe (16). The first pipe (10) is provided with an additional wall (12) in the region of its penetration which is also penetrated and which cooperates with the first pipe wall (10) to define a cavity (15) through which an inert fluid flows. Any failure of the seal (20) at the junction between the additional wall (12) and the second pipe (16) results in any fluid within the pipes (10, 16) leaking into the flow of inert fluid, not the environment externally of the pipes (10, 16). In use, e.g. in a heat exchanger, the pressure of the inert fluid is intermediate that of the fluid in the pipes and that of the environment externally of the pipes. <IMAGE>

Description

PIPE CONNECTION This invention relates to the connection of pipes and is particularly concerned with the connection of pipes which are adapted to carry a fluid which is reactive with the environment externally of the pipes or which is classed as being hazardous in that external environment.

It is sometimes necessary to provide a connection between pipes which, in operation are adapted to carry a fluid which, if it came into contact with the environment externally of the pipes, could react with the environment in an undesirable or dangerous manner or could be hazardous in that environment, as, for instance, a pollutant. There are many situations in which such a situation exists in, for instance, the chemical and nuclear industries.

It is an object of the present invention to provide a connection between the pipes which, in the event of a failure of that connection, would not result in an intermixing of any fluid contained within the pipes and the environment externally of the pipes.

According to the present invention, a pipe connection comprises a first pipe in fluid flow communication with a second pipe and means providing a fluid seal at the junction between said pipes, said junction between said pipes being enclosed on one side thereof by means defining a cavity adjacent the total extend of said fluid seal which cavity is operationally purged by a flow therethrough of a fluid which is inert with respect to any fluid within said pipes and also with respect to the environment externally of said pipes, said inert purging fluid being at a lower pressure than any fluid contained within said pipe and at a higher pressure than that of said environment.

The invention will now be described, by way of example, with reference to the accompanying drawing, which is a sectioned side view of a pipe connection in accordance with the present invention.

With reference to the drawing, a first circular cross-section pipe 10 is defined by a wall 11 and encloses a second wall 12. The second wall 12 is integral with the first wall 11 at its edges 13 and 14 but is otherwise spaced apart from the first wall 11 so that together they define a crescent cross-section shape cavity 15 which extends along the whole length of the first pipe 10. Although the additional wall 12 is shown as being internally of the first pipe 10, it could if so desired be externally thereof.

The walls 11 and 12 are penetrated by a second pipe 16, which is one of a plurality of similar pipes which also penetrate the walls ll and 12, two of which 17 and 18 can also be seen in the drawing. The first pipe 10 and second pipes 16,17 and 18 constitute a portion of a multi-tube heat exchanger although it will be appreciated that the present invention is also applicable to other components which comprise a plurality of pipes in fluid communication with each other.

The second pipe 16 is sealed by brazing, as can be seen at 19 and 20, to the walls ll and 12 respectively and projects into the interior of the first pipe 10 so that the first and second pipes 10 and 16 are in fluid flow communication with each other.

The first and second pipes 10 and 16 operationally contain liquid hydrogen at a pressure which is higher than that of the environment A externally of the pipes 10 and 16. The environment A comprises air so that any leakage of liquid hydrogen into that air would result in a gaseous mixture which could react explosively if ignited. The most likely site of any leakage which would bring about an intermixing of the contents of the first and second tubes 10 and 16 and the environment A would be the braze joints 19 and 20 between the first and second tubes lO and 16. However in operation, the cavity 15 has flowing through it a fluid, such as argon, which is inert with respect to both the contents of the tubes 10 and 16 and the environment A surrounding the tubes 10 and 16.

The argon is arranged to be at a pressure which is lower than that of the liquid hydrogen within the tubes 10 and 16 but higher than that of the air of the environment A.

Consequently if the braze seal 20 between the second tube 16 and the wall 12 should fail, liquid hydrogen would flow into the cavity 15 to be purged by the flow of argon through the cavity 15, thereby obviating the risk of the hydrogen mixing with air in the environment A. Likewise if the braze seal 19 between the tube wall 11 and the second pipe 16 were to fail, argon would leak into the air of the environment A, again avoiding the dangerous mixing of hydrogen with air. In the unlikely event of both of the braze seals 19 and 20 failing, the problem would not be as serious as it would be in the case of a direct leakage of hydrogen into the air since any fluid leaked into the environment A.would contain only a minor proportion of hydrogen, the majority of the fluid being argon.

Although the present invention has been described with reference to tubes 10 and 16 which constitute a portion of a heat exchanger, it will be appreciated that it is generally applicable to any pipe connection in which the pipes carry a fluid whether liquid or gaseous which could react adversely with the environment surrounding the pipes or which could be hazardous in that environment.

Claims

Claims:

1. A pipe connection comprising a first pipe in fluid flow communication with a second pipe and means providing a fluid seal at the junction between said pipes, said junction between said pipes being enclosed on one side thereof by means defining a cavity adjacent the total extent of said fluid seal which cavity is operationally purged by a flow therethrough of a fluid which is inert with respect to any fluid within said pipes and also with respect to the environment externally of said pipes, said inert purging fluid being at a lower pressure than any fluid contained within said pipes and at a higher pressure than that of said environment.

2. A pipe connection as claimed in claim 1 wherein said first pipe is in fluid flow communication with said second by virtue of the penetration of said first pipe by said second pipe.

3. A pipe connection as claimed in claim 2 wherein said means defining said cavity adjacent the total extent of said fluid seal comprises a wall which is integral with said first pipe so as to provide a double wall construction therewith defining said cavity and which is penetrated by said second pipe.

4. A pipe connection as claimed in claim 3 wherein said wall is located internally of said first pipe.

5. A pipe connection as claimed in claim 3 or claim 4 wherein said wall extends along the full length of said first pipe.

6. A pipe connection substantially as hereinbefore described with reference to and as shown in the accompanying drawing.