GB1591659A

GB1591659A - Method of connecting a tube to an apertured body

Info

Publication number: GB1591659A
Application number: GB3688177A
Authority: GB
Original assignee: Serck Industries Ltd
Current assignee: Serck Industries Ltd
Priority date: 1977-09-03
Filing date: 1977-09-03
Publication date: 1981-06-24

Description

(54) A METHOD OF CONNECTING A TUBE TO AN APERTURED BODY (71) We, SERCK INDUSTRIES LIMITED, a British company of P.O. Box 598B, Warwick Road, Birmingham Bi 1 2QY, West Midlands, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to ube performed to be described in the following statement: This invention relates to a method of connecting a tube to an apertured body, such as a plate, the method being particularly applicable to the construction of a tubestack for a heat exchanger.

According to the invention, a method of connecting a tube to an apertured body comprises forming a tapered counterbore in the body substantially concentric with the body aperture, inserting the tube into the aperture so that its extends at least partially into the counterbore at the narrower end of the latter, locating the tube in position in the body by introducing into the counterbore from the wider end of the latter and between the internal surface of the counterbore and the external surface of the tube at least one generally annular metal insert of which the wall is of uniform thickness throughout and parallel to its longitudinal axis, and securing the tube and body together.

Conveniently, the tube and body are finally secured together by soldering or brazing.

One particular field of use of the invention is in the construction of a tubestack having at least one tube assembly comprising substantially concentric tubes, of which an inner tube projects beyond an outer tube thereof, adjacent end portions of the tubes being connected respectively to a pair of spaced apertured tube plates. With such a construction, an aperture in a first of the tube plates is adapted to receive the outermost tube, a counterbore is formed at one end of the aperture, the tube assembly is inserted into the aperture so that the outer tube lies within the counterbore and the inner tube projects beyond the counterbored face of the tubeplate, said at least one insert is introduced into the counterbore to locate the outer tube in position in the tubeplate, the outer tube and tubeplate are finally secured together and the projecting end of the inner tube is secured to the second tubeplate. The inner tube may conveniently be secured to the second tubeplate by mechanical means such as roller expansion.

The invention will now be described, by way of example, with reference to the accompanying drawings in which: 'Figure 1 is a diagrammatic sectional view of one end portion of a tube assembly of a heat exchanger tubestack; Figure liA is a transverse cross-section of the tube assembly of Figure 1 Figure 2 is an enlarged fragmentary crosssection of a tubeplate of a heat exchanger tubestack showing a tube-receiving hole therethrough; Figure 3 shows one form of insert fore use in carrying out the method of the invention, and Figures 4 and 5 show respectively two stages in the connection of the tube assembly of Figure 1 to tube plates by the method of the invention, to form a tubestack.

Referring to the drawings, Figures 1 and 1A show diagrammatically a typical concentric tube assembly for use in a heat exchanger and including an inner tube 1 protruding from an outer tube 2, the inner surface of the outer tube being provided at intervals therearound with longitudinal flutes 3 extending along the entire length of the outer tube, the flutes constituting an escape path for fluid leaking through the wall of either of the tubes 1 and 2. The flutes may alternatively or additionally be formed in the outer surface of the inner tube.

In a completed heat exchanger, the inner and outer tubes 1 and 2 are secured respectively to first and second tube plates 4 and 5 and the securing of the tubes is effected in two stages as illustrated respectively in Figures 4 and 5. The tube plate 5 is provided with a through-hole '6 to receive the outer tube 2 of the tube assembly. The hole 6 is constituted by a cylindrical portion 7 and has a counterbore 8, which is tapered as shown, the angle of taper being typically in the region of 8" (Figure 2). The counterbore may alternatively be of any convenient form and extend for any convenient distance along the hole 6. A plain annulus 9, for example of copper, (Figure 3) is provided for use in carrying out the method of the invention, as will be described hereafter.

The ring 9 has an outer diameter very slightly smaller than the major diameter of the counterbore 8 and an internal diameter slightly larger than the outside diameter of the outer tube 2. The length of the ring 9 is approximately the same as the depth of the counterbore 8 and the ring 9 may con leniently be cut from a copper tube of appropriate dimensions. The ring, as shown, therefore has a wall of uniform thickness throughout and parallel to the central axis thereof.

The first stage in connecting the tube assembly to the tubeplates 4 and 5 is to connect the outer tube 2 to the tubeplate 5 which will be the innermost tubeplate in use.

This first stage is illustrated in Figure 4 and it will be seen that the tube assembly is inserted through the tubeplate 5 to a position in which the end 10 of the tube 2 is substantially flush with the outermost surface 11 of the tubeplate and the inner tube 1 extends beyond that surface. The ring 9 is then forced. into the tapered recess between the outer surface of the tube 2 and the counterbore 8. This action causes the ring to grip tightly on to the outer surface of the tube 2 so as, effectively to lock the tube in position, the ring also deforming so as substantially to follow the taper of the counterbore, as shown. Once the tube has been locked in position in this manner, a fluid tight joint can be formed by applying solder to the side of the tubeplate 5 remote from the ring, the solder flowing down the inevitable small clearance between the tube- plate and tube as far as the inner end of the ring and forming a coating outwardly for some distance on the tubeplate 5. At this point, the outer tube side of the heat exchanger can be subjected to pressure test and any detected, leaks rectified.

The final stage of assembly is to insert the protruding end portion of the inner tube 1 into a suitably sized hole in the tubeplate 4 and connect the two together in any convenient manner such as by roller expansion (Figure 5).

It will be appreciated that the use of the ring 9 in the manner descrilbed with a fluted concentric tube construction precludes the possibility of solder or braze from leaking beyond the face 11 of the tubeplate 5 and risking blocking the flutes 3. Moreover, the mechanical locking effected by the ring provides a tubestack assembly consisting of the tubeplate 5 and tube assembly and this can be easily handled without distortion or movement of individual components and enables soldering or brazing to be carried out in the most convenient attitude of the tubestack without the necessity to use jigs and fixtures.

Although the above description has dealt with securing a single tube assembly to one pair of tubeplates, it will be understood that a normal tubestack includes a large number of tube assemblies, each of which will be fixed by the method of the invention to a pair of tubeplates at both ends of the assembliss.

The invention includes a heat exchanger tubestack made in accordance with the method of the invention.

WHAT WE CLAIM IS: 1. A method of connecting a tube to an, apertured body comprising forming a tapered counterbore in the body substantially concentric with the body aperture, inserting the tube into the aperture so that it extends at least partially into the counterbore at the narrower end of the latter, locating the tube in position in the body by introducing into the counterbore from the'wider end of the latter and between the internal surface. of the counterbore and the external surface of the tube at least one generally annular metal insert of which the wall is of uniform thickness throughout and parallel to its longitudinal axis, and securing the tube and body together.

2. A method according to Claim 1 wherein the tube and body are finally secured together by soldering or brazing.

3. A method according to Claim 1. or Claim 2 wherein the tube is inserted into the counterbore from the narrower end thereof.

4. A method according to Claim 1 or Claim 2 for connecting a tube assembly to a pair of spaced apertured tubeplates, the tube assembly having substantially concentric tubes of which an inner tube projects beyond an outer tube thereof, and a first of the tubeplates has an aperture adapted to receive the outermost tube and a counterbore formed at one end of the aperture, in which method the tube assembly is inserted into the aperture so that the outer tube lies within the counterbore and the inner tube projects beyond the counterbored face of the tubeplate, said at least one insert is introduced into the counterbore to locate the outer tube in position in the tubeplate, the outer tube and tube plate are finally secured together and the projecting end of the inner tube is secured to the second tubeplate.

5. A method according to Claim 4 wherein the inner tube is secured to the second tulbe plate by a mechanical process.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **.

6 is constituted by a cylindrical portion 7 and has a counterbore 8, which is tapered as shown, the angle of taper being typically in the region of 8" (Figure 2). The counterbore may alternatively be of any convenient form and extend for any convenient distance along the hole 6. A plain annulus 9, for example of copper, (Figure 3) is provided for use in carrying out the method of the invention, as will be described hereafter.

The ring 9 has an outer diameter very slightly smaller than the major diameter of the counterbore 8 and an internal diameter slightly larger than the outside diameter of the outer tube 2. The length of the ring 9 is approximately the same as the depth of the counterbore 8 and the ring 9 may con leniently be cut from a copper tube of appropriate dimensions. The ring, as shown, therefore has a wall of uniform thickness throughout and parallel to the central axis thereof.

The first stage in connecting the tube assembly to the tubeplates 4 and 5 is to connect the outer tube 2 to the tubeplate 5 which will be the innermost tubeplate in use.

This first stage is illustrated in Figure 4 and it will be seen that the tube assembly is inserted through the tubeplate 5 to a position in which the end 10 of the tube 2 is substantially flush with the outermost surface 11 of the tubeplate and the inner tube 1 extends beyond that surface. The ring 9 is then forced. into the tapered recess between the outer surface of the tube 2 and the counterbore 8. This action causes the ring to grip tightly on to the outer surface of the tube 2 so as, effectively to lock the tube in position, the ring also deforming so as substantially to follow the taper of the counterbore, as shown. Once the tube has been locked in position in this manner, a fluid tight joint can be formed by applying solder to the side of the tubeplate 5 remote from the ring, the solder flowing down the inevitable small clearance between the tube- plate and tube as far as the inner end of the ring and forming a coating outwardly for some distance on the tubeplate 5. At this point, the outer tube side of the heat exchanger can be subjected to pressure test and any detected, leaks rectified.

The final stage of assembly is to insert the protruding end portion of the inner tube 1 into a suitably sized hole in the tubeplate 4 and connect the two together in any convenient manner such as by roller expansion (Figure 5).

It will be appreciated that the use of the ring 9 in the manner descrilbed with a fluted concentric tube construction precludes the possibility of solder or braze from leaking beyond the face 11 of the tubeplate 5 and risking blocking the flutes 3. Moreover, the mechanical locking effected by the ring provides a tubestack assembly consisting of the tubeplate 5 and tube assembly and this can be easily handled without distortion or movement of individual components and enables soldering or brazing to be carried out in the most convenient attitude of the tubestack without the necessity to use jigs and fixtures.

Although the above description has dealt with securing a single tube assembly to one pair of tubeplates, it will be understood that a normal tubestack includes a large number of tube assemblies, each of which will be fixed by the method of the invention to a pair of tubeplates at both ends of the assembliss.

The invention includes a heat exchanger tubestack made in accordance with the method of the invention.

WHAT WE CLAIM IS: 1. A method of connecting a tube to an, apertured body comprising forming a tapered counterbore in the body substantially concentric with the body aperture, inserting the tube into the aperture so that it extends at least partially into the counterbore at the narrower end of the latter, locating the tube in position in the body by introducing into the counterbore from the'wider end of the latter and between the internal surface. of the counterbore and the external surface of the tube at least one generally annular metal insert of which the wall is of uniform thickness throughout and parallel to its longitudinal axis, and securing the tube and body together.
2. A method according to Claim 1 wherein the tube and body are finally secured together by soldering or brazing.
3. A method according to Claim 1. or Claim 2 wherein the tube is inserted into the counterbore from the narrower end thereof.
4. A method according to Claim 1 or Claim 2 for connecting a tube assembly to a pair of spaced apertured tubeplates, the tube assembly having substantially concentric tubes of which an inner tube projects beyond an outer tube thereof, and a first of the tubeplates has an aperture adapted to receive the outermost tube and a counterbore formed at one end of the aperture, in which method the tube assembly is inserted into the aperture so that the outer tube lies within the counterbore and the inner tube projects beyond the counterbored face of the tubeplate, said at least one insert is introduced into the counterbore to locate the outer tube in position in the tubeplate, the outer tube and tube plate are finally secured together and the projecting end of the inner tube is secured to the second tubeplate.
5. A method according to Claim 4 wherein the inner tube is secured to the second tulbe plate by a mechanical process.
6. A method according to Claim 5 where*.-

in said mechanical process is roller expansion.
7. A method according to Claim 4 wherein at least one passage is formed between the contiguous walls of the concentric tubes, the passage extending to at least one end of the tube assembly and communicating with the space between the tubeplate to provide an escape path for fluid leakage through one of said walls.
8. A method of connecting a tube to an apertured body substantially as hereinbefore described with reference to the accompanying drawings.
9. A tubestack constructed in accordance with the method of any one of the preceding claims.
10. A tubestack according to Claim 9 when appendant to Claim 3 wherein at least one passage is provided between contiguous walls of the concentric tubes, the passage extending to at least one end of the tube assembly and communicating with the space between the tubeplate to provide an escape path for fluid leaking through one of said walls.
11. A heat exchanger incorporating a tubestack according to Claim 9 or Claim 10.