FR2484875A1 - - Google Patents

Abstract

THE INVENTION RELATES TO A PROCESS FOR ACHIEVING THE PRESSURE-TIGHT FIXING OF PIPES ON AT LEAST ONE WALL. ACCORDING TO THIS PROCEDURE, ACCORDING TO WHICH THE END OF A TUBE 3 IS INSERTED IN A DRILLING OF A WALL 1, THE DIAMETER OF WHICH IS SLIGHTLY GREATER THAN THE OUTER DIAMETER OF TUBE 3, AND IS ENLARGED OR LAMINATED OVER PART OF ITS ZONE LOCATED IN WALL 1, INSERT BETWEEN THE END OF TUBE 3 AND THE INSIDE SURFACE OF THE DRILLING A METAL SEALING MATERIAL 4 AT LEAST ON A PART OF THE END OF TUBE 3 LOCATED IN WALL 1 AND DONE SUBJECT TO AN ENLARGEMENT OR MECHANICAL EXPANSION BY LAMINATION TO THE ENTIRE SO THAT THE PRESSURE OBTAINED AFTER THIS OPERATION BETWEEN THE END OF TUBE 3 AND WALL 1 KEEP THE SEALING MATERIAL ABOVE ITS APPARENT ELASTICITY LIMIT. APPLICATION IN PARTICULAR TO HEAT EXCHANGERS AND COLLECTORS.

Description

The present invention relates to a method for carrying out the

  pressure-tight fixing of tubes on at least one wall,

  especially in the case of the manufacture of heat exchangers or col-

  readers, and that the ends of the tubes are inserted, while respecting a predetermined axial position, in metal bores.

  swimming in the flat or curved wall and whose diameter is light-

  greater than the outer diameter of the tubes, and are hydraulically expanded and / or mechanically expanded by rolling at least part of their area in the wall, with a view to

  their application without play against the latter.

  He is known, especially in the field of manufacturing

  heat exchangers, insert the ends of the tubes of the

  of heat with a certain clearance in the holes of a plate

  te-tubes and perform a mechanical expansion by rolling or

  hydraulic trimming of these ends at this plate

  tubes for application without play. In order that the tube to be applied against the wall of the bores does not move inside the tube-carrying plate during the operation of mechanical expansion by rolling or expansion, the tube is fixed at its front edge to the tube plate by means of mechanical expansion or welding. the welding of the front edge of the tube on the outer face of the

  pipe plate also provides the required sealing.

  In order to guarantee, during the construction of heat exchangers

  their high quality, of the type used for example in power plants

  that the application of the ends of the tubes against the

  The holes in the tube plate are made without the applica-

  excessive stress on the tubes and without the appearance of slits

  between the tube and the tube plate, a procedure is known

  which uses a combination of hydraulic expansion and

  mechanical expansion by rolling in the enlarged part by hydrau-

  lic. Shortening the part of hydraulic widening

  less than the thickness of the pipe support plate

  As the tube, which must be applied against the walls of the bore, is not subjected to excessive stress at its projecting portion out of the pipe plate. The annular gap, which remains between the tube and the tube-bearing plate due to this narrowing of the enlarged part, is then closed by the fact that, under

  the effect of mechanical expansion by subsequent rolling in the

  hydraulically enlarged section, the tube is pushed back, at least on

  the missing length, towards the outside of the tube plate.

  Even in the case of this process developed for samples

  heat generators for use in nuclear power plants, it is necessary in practice to weld the front edge of the tube to the tube-holder plate in order to fix the tubes in their position relative to the pipe plate before the expansion or mechanical expansion operation

  by rolling, and to ensure the other required sealing. This sou-

  However, the removal of the tubes from the tube plate not only results in a high labor expenditure, but requires

  also, like the fixation also known by

  of the tubes by means of abutment surfaces acting in an axial direction between the tube and the tube

  voluntarily implement the enlargement or expansion

  mechanical bonding in a zone connecting to the front edge of the tubes to prevent damage to the weld seam or abutment surfaces. In the known processes, it is necessary to accommodate the annular slots then necessarily appearing between the tube and

the tube plate.

  From the state of the art described above, the object of the invention is to provide a method for fixing, pressure-tight, tubes on at least one wall and which avoids the disadvantages described above and provides, even in the case of the occurrence of high pressures or pressure differences

  high and / or high temperatures, a pressure-tight

  without welding, requiring a lot of work, tubes on the

  tube plate and without the appearance of cracks sensitive to corrosion

  and difficult to decontaminate.

  Your solution brought by the invention to the problem posed is

  characterized by installing a metal sealing material

  between the end of the tube and the inner surface of the bore on at least a portion of the end of the tube in the wall, and

  that is expanded or subjected to mechanical expansion by rolling the

  of the tube while simultaneously deforming the sealing material in such a way that the pressure which prevails after the enlargement operation

  mechanical expansion by rolling between the end of the tube and the

  king, maintain the sealant above its elastic limit.

apparent ticity.

  With the aid of the process according to the invention, not only

  a good seal between the tube and the wall, which acts on the

  seems of the lifetime of the device and which also supports pressures of the order of 40 MPa or pressure differences of the order of 30 MPa and can face high temperatures of the order of 4000C

  as well as corrosive fluids, but also, because of the presence of

  this metal sealing material, a good heat transfer

  the tube and the wall, which is particularly important in the case of devices subject to high stresses, such as for example heat exchangers and collectors. The sealing obtained by means of the process according to the invention corresponds to a connection by welding, since the metallic sealing material is maintained, in all operating states, above its yield strength.

  apparent and below its melting point, which provides an

  always optimal sealing. At the same time, the material of

  metal dullness prevents the appearance of thermal insulation at

  calf of the contact surface between the tube and the wall of the bore, so that the heat transfer is improved over known methods. Finally, the metal sealing material prevents a test

  ultrasonic penetration of the borehole wall is disturbed by the

  be the wall of the tube and the wall of the bore.

  According to another characteristic of the invention, before

  tion of the tube in the bore of the wall, the end of the tube is

  provided with a coating consisting of the metallic sealing material

  than. This improvement has the effect that the sealing material differs from

  fuse in the boundary layers of the tube and the wall of the borehole,

  that sealing action and heat transfer are

  improved. The deposition of the coating constituted by the sealing material

  metal can be achieved in different ways, for example se-

  the immersion, galvanizing or projection process

  plasma. In all cases it is certain that, in

  sonic, there will be no erroneous indication due to air inclusions.

  According to another possible embodiment of the method according to

  me to the invention, it is proposed to equip the cylindrical bore of the

  wall, at least one radial enlargement and to introduce into this

  deny an annular sealing material before inserting the end of the

  tube in the piercing, and expand or subject to a metal expansion

  by rolling the end of the tube also over the whole area of the radial enlargement, by means of simultaneous deformation

sealing material.

  Due to the radial enlargement, located in the cylindrical bores and which is made according to another feature of the invention preferably with a continuous contour in axial section, after the operation of expansion or mechanical expansion by rolling, an axial determination of the position of the tube in the wall,

  without the need for that purpose to use

  abutments. the sealing material, which is located in the area of the radial widening between the tube and the tube-carrying plate and which

  is deformed during the expansion or mechanical expansion operation.

  by rolling, provides, between the tube and the tube-holder plate, a good active seal throughout the service life of the assembly and which also supports pressures of the order of 40 4 Pa or pressure differences of order of 30 MPa and can withstand high temperatures of the order of 4000 C as well as corrosive fluids.

  As an example, we have described below and illustrated

  only two examples of the implementation of the pro-

granted according to the invention.

  Figure 1 shows a section of a cylindrical bore formed in the wall of a collector; FIG. 2 shows the end, partially encased, of a tube to be fixed in the wall of the collector of FIG. 1; Figure 3 is a sectional view corresponding to Figures 1 and 2 and on which the end of the tube is shown inserted into the bore of the wall of the collector; Figure 4 shows a section, corresponding to that of Figure 3, after enlargement of the end of the tube in the wall of the collector; Figure 5 shows a representation, corresponding to that of Figure 4, but on which a radial enlargement is provided in the bore of the wall of the collector for the axial attachment of the tube after the widening;

  FIG. 6 shows a section of a piercing provided with an elongated

  radial grooving and formed in the tube-carrying plate; Figure 7 shows a section corresponding to that of Figure 6 and on which an annular sealing material has been inserted into the radial enlargement; Figure 8 shows a tube end inserted in the bore of Figure 7; Figure 9 shows a longitudinal section of the tube end fixed in a pressure-tight manner and without the possibility of axial displacement in the tube-carrying plate; and FIG. 10 represents a top view of a ring dl

  open seal, the edges of which are superimposed.

  FIG. 1 shows a part of a wall 1, for example of a collector, in which a hole is made

  2. In the latter must be attached a tube 3, the end

  The outer diameter of the tube 3 coated with the sealing material 4 is smaller than the diameter of the bore 2, so that the tube 3 can

  to be inserted, in accordance with Figure 3, into the wall I of the

  tor. By means of hydraulic expansion or mechanical expansion by rolling, the diameter of the end of the tube 3 located in the wall 1 is increased while simultaneously deforming the sealing material 4 at the same time. after the operation of expansion or mechanical expansion by rolling between the end of the tube and the wall 1, maintains the sealing material 4 above its yield strength, so that this material achieves a good sealing, active throughout the duration of the assembly, between the tube 3 and the wall 1 and ensures simultaneously

  a good heat transfer between the tube 3 and the wall 1.

  In the modified embodiment of Figure 5, the representation of which corresponds to that of Figure 4, there is provided in the cylindrical bore 2 of the wall 1, a radial enlargement 5 which has a continuous contour in axial section. During the expansion or the mechanical expansion by rolling, the tube 3 as well as the sealing material 4 is applied against the surface of the enlargement wall 5, thereby fixing the tube 3 according to the

axial direction.

  FIGS. 6 to 9 show a small wall 1 of a tube plate of a heat exchanger which also has

  a cylindrical bore 2. This bore 2 is again equipped with a

  radial groove 5 which has a continuous contour in axial section, so that there is no sharp-edged angle, nor any discon-

  sharpness in the longitudinal direction of the enlarged hole 2.

  In the cylindrical bore 2, equipped with the radial expansion 5 according to FIG. 6, an annular sealing material 4 is inserted in such a way that the latter does not prevent the insertion of a tube. 3 and on the other hand is not pushed out of the radial expansion 5. The outer diameter of the tube 3 is slightly smaller than the diameter of the cylindrical bore 2, so

  that the tube 3 of FIG. 3 is situated with a certain clearance in the

  2 of the wall 1. The front surface 5a of the tube 3 may be aligned level with the outer surface 1a of the wall 1, or project slightly from this outer surface.

  la, as shown in Figure 8.

  After the insertion, shown in FIG. 8, of the tube 3 in the cylindrical bore 2 and the position determination then carried out, the tube 3 is subjected to hydraulic expansion and / or mechanical expansion by rolling, with a view to its application. without backlash against the wall 1. The hydraulic widening and / or the mechanical expansion by rolling are carried out at least in an area of the part of the tube 3 located in the wall 1. It is also possible to use a combination of two processes. In all cases, it is certain that the tube 3 undergoes a widening or a mechanical expansion by rolling also over the entire area of the radial expansion 5, so that the sealing material 4 is simultaneously deformed, as shown in FIG. 9, the pressure, which prevails after the operation of widening or mechanical expansion by rolling between the tube 3 and the wall 1, is sufficiently greater

  at the apparent yield strength of the metal sealant

  so that the sealing action of the latter is guaranteed,

  in the state shown in FIG. 9, in all cases of operation

  tioning. Increasing the diameter of the tube 5 in the region of the radial widening 5 ensures, in the final state in accordance with FIG. 9, that the tube 3 is held simultaneously without the possibility of axial displacement in the wall 1, without which it is necessary to use for this purpose a particular and additional fixation,

for example by welding.

  As shown in Figure 10, the ring formed by the material

  The sealing ring 4 is open to facilitate its insertion into the widening 5 of the piercing 2. The diameter of an open ring can be reduced when it is pushed back through the cylindrical bore 2 in the enlargement 5. Next, the ring exerts an elastic spacing action and assumes the position shown in FIG. 7. In order to guarantee a uniform distribution of the sealing material 4 after the operation of mechanical expansion by rolling or enlarging the tube 3, the edges of the ring constituted by the sealing material

  are overlapping, as shown in Figure 10.

  As regards the coefficient of thermal expansion of the metallic sealing material, it is possible to approach, by alloying, coefficients of thermal expansion of the materials of which the tube and the wall are constituted. This ensures that even large variations in temperature, for example in the high temperature range, during operation, do not cause any thermal expansion of variable intensity which may cause leakage due to the occurrence of annular cracks. .

Claims (6)

  1. Method for making the fastening, waterproof to the pressure   of tubes on at least one wall (1), in particular in the case of the manufacture of heat exchangers or collectors, and in which the ends of the tubes (3) are inserted, while respecting a predetermined axial position, in bores (2) formed in the flat or curved wall (1) and whose diameter is slightly greater   the outer diameter of the tubes (3), and are hydraulically expanded   and / or undergo mechanical expansion by rolling at least on   part of their area in the wall; for their application   without play against the latter, characterized in that a metal sealing material (4) is introduced between the end of the tube (3) and the inner surface of the bore (2) on at least a portion of the end of the tube located in the wall, and is subjected to a process of expansion or mechanical expansion by rolling at the end of the tube by simultaneously deforming the sealing material (4), so that the pressure, which reigns between the end of the tube (3) and the wall (1) after the enlargement or expansion operation   mechanically by rolling, maintain the sealing material (4)   above its apparent yield strength.   2. Method according to claim 1P characterized in that   a coating consisting of the metal sealing material is   lique (4) on the end of the tube, before insertion into the bore.   3. Method according to claim 1, characterized in that one arranges at least one radial expansion (5) in the cylindrical bore (2) of the wall and is inserted in this enlargement an annular sealing ring (4) before inserting the end of the tube (3) in the bore (2), and an enlargement operation is carried out   or mechanical expansion by rolling at the end of the tube (3)   over the whole area of radial   simultaneous deformation of the sealing material (4).   4. Method according to claim 3, characterized in that the radial enlargement (5) is carried out with a continuous contour in axial section.   5. Process according to claims 3 and 4 taken in   together, characterized in that the ends of the ring   formed by the metallic sealing material (4) are superimposed one to the other.   6. Process according to any one of claims 1 to   characterized in that for the coefficient of thermal expansion of the metallic sealing material (4), the coefficient of thermal expansion of the material constituting the tube (3) and the wall (1).