Method for manufacturing a double-wall heat-exchanger tube

Patent metadata

Field	Value
Publication number	US-12397339-B2
Application number	US-202418679687-A
Country	US
Kind code	B2
Filing date	May 31, 2024
Priority date	Jun 2, 2023
Publication date	Aug 26, 2025
Grant date	Aug 26, 2025

Abstract

A method for manufacturing a double-wall heat-exchanger tube including an external tube and an internal tube, these tubes being metallic, cylindrical and coaxial. This method includes providing a first tube having an inside diameter d1int and an outside diameter d1ext, this first tube being intended to form the external tube, a second tube having an inside diameter d2int and an outside diameter d2ext, this second tube being intended to form the internal tube, and a cylindrical coaxial tubular leaf made from Fe0 having an inside diameter dint and an outside diameter dext, such that 0.15 mm≤(d1int−dext)≤0.25 mm, 0.15 mm≤(dint−d2ext)≤0.25 mm, and 10 μm≤(dext−dint)≤200 μm.

First claim

The invention claimed is:

1. A method for manufacturing a double-wall heat-exchanger tube comprising an external tube and an internal tube, the external and internal tubes being metallic, cylindrical and coaxial, said manufacturing method comprises the following successive steps (i) to (vii):
(i) providing:
a first tube having an inside diameter d 1int and an outside diameter d 1ext , said first tube being intended to form the external tube,
a second tube having an inside diameter d 2int and an outside diameter d 2ext , said second tube being intended to form the internal tube, and
a cylindrical tubular leaf made from Fe 0 having an inside diameter d int and an outside diameter d ext ,

such that

0.15

mm

≤

(

d

1
⁢
int

-

d
ext

)

≤

0.25

mm

,

0.15

mm

≤

(

d
int

-

d

2
⁢
ext

)

≤

0.25

mm

,
and

10
⁢

μm

≤

(

d
ext

-

d
int

)

≤

200
⁢

μm

;

(ii) forming a coaxial assembly of the second tube and of the leaf inside the first tube, the leaf being positioned between the first and second tubes;
(iii) brazing or bonding of one end of the coaxial obtained at the end of step (ii);
(iv) generating a co-deformation of the coaxial co-deformed assembly obtained at the end of step (iii) to obtain a co-deformed assembly:
(v) cutting ends of the co-deformed assembly obtained at the end of step (iv);
(vi) welding the cut ends of the co-deformed assembly obtained at the end of step (v); and
(vii) performing a heat treatment of the assembly obtained at the end of step (vi), said heat treatment being implemented by hot isostatic pressing, with which the double-wall heat-exchanger tube is obtained.

2. The method according to claim 1 , wherein the first and second tubes provided at step (i) are devoid of welding.

3. The method according to claim 2 , wherein each of these first and second tubes have been obtained by implementing, prior to step (i), the following successive steps (i 0 ) and (i 1 );
(i 0 ) hot spinning or hot rolling of a pierced rod, with which a tubular blank is obtained, and
(i1) cold drawing or pilger rolling of the tubular blank as obtained at the end of step (i 0 ).

4. The method according to claim 1 , wherein the tubular leaf provided at step (i) is devoid of welding.

5. The method according to claim 4 , wherein step (i 4 ) of pilger rolling is reproduced at least once.

6. The method according to claim 5 , the method further comprises a heat treatment step (i 4 ′).

7. The method according to claim 6 , wherein heat treatment step (i 4 ′) is conducted between each step (i 4 ).

8. The method according to claim 6 , wherein heat treatment step (i 4 ′) is conducted at 850° C. for 1 hour.

9. The method according to claim 4 , wherein the tubular leaf provided at step (i) is obtained by implementing, prior to step (i), the following successive steps (i 2 ) to (i 4 ):
(i 2 ) drilling of a rod made from iron Fe 0 ,
(i 3 ) turning of the drilled rod as obtained at the end of step (i 2 ), with which a tubular blank is obtained, and
(i 4 ) pilger rolling of the tubular blank as obtained at the end of step (i 3 ).

10. The method according to claim 1 , further comprising a step of cleaning at least drilled of the first tube, pilger of the tubular leaf and an external surface of the second tube, said cleaning step being implemented prior to the coaxial assembly step (ii).

11. The method according to claim 1 , wherein the co-deformation step (iv) is implemented by co-drawing or by co-rolling, and by pilger co-rolling, of the coaxial assembly obtained at the end of step (iii).

12. The method according to claim 1 , which does not comprise a degassing step between the co-deformation step (iv) and the welding step (vi).

13. The method according to claim 1 , wherein the welding step (vi) is implemented by an arc welding method with a non-meltable a electrode, and without addition of material.

14. The method according to claim 13 , wherein the non-meltable electrode is made from tungsten.

15. The method according to claim 1 , wherein step (vii) is implemented at a temperature of between 800° C. and 1200° C., at a pressure of between 50 MPa and 200 MPa and for a period of between 30 minutes and 4 hours.

16. The method according to claim 1 , further comprising, after step (vii), one or more of the following steps (viii) to (xii):
a (viii) cooling of the double-wall heat-exchanger tube;
(ix) curving of the double-wall heat-exchanger tube obtained at the end of step (viii);
(x) expanding the double-wall heat-exchanger tube obtained at the end of step (viii) or (ix);
(xi) heat treating the double-wall heat-exchanger tube obtained at the end of step (ix) or (x); and
(xii) straightening of the double-wall heat-exchanger tube obtained at the end of step (ix), (x) or (xi).

17. The method according to claim 16 , wherein cooling step (viii) is carried out at a rate of 50° C./hour.

18. The method according to claim 16 , wherein heat treating step (xi) is carried out by quenching or normalised ageing.

19. The method according to claim 1 , wherein the first and second tubes are made from martensitic stainless steel, from Eurofer-97 or from T-91 steel.

20. The method according to claim 1 , wherein the materials of the first and second

Assignees

• Commissariat Energie Atomique

Inventors

• Sornin Denis

Classifications

• B32B15/011

  all layers being formed of iron alloys or steels · CPC title

• B32B1/08

  Tubular products · CPC title

• F28F21/089

  Coatings, claddings or bonding layers made from metals or metal alloys (F28F19/06 takes precedence) · CPC title

• F28F2275/04

  by brazing · CPC title

• F28F2250/00

  Arrangements for modifying the flow of the heat exchange media, e.g. flow guiding means; Particular flow patterns · CPC title