EP1064486A2

EP1064486A2 - Tube having an expansion area and method for producing such a tube

Info

Publication number: EP1064486A2
Application number: EP99919027A
Authority: EP
Inventors: Winfried Hehn
Original assignee: Siemens AG
Current assignee: Areva GmbH
Priority date: 1998-03-17
Filing date: 1999-03-04
Publication date: 2001-01-03
Also published as: WO1999047843A3; DE19811599C2; DE19811599A1; WO1999047843A2

Abstract

The invention relates to a tube (7 or 21) with an expansion area (25 or 25A, 25B) presenting a roughness (26 or 26A, 26B). In this area, for example a heat exchanger tube (7A) can be fixed by expanding the tube wall (23). The roughness (26 or 26A, 26B) is generated by roughening the tube wall (23) and applying a coat (31) of deformable metal, especially a nickel material, onto the roughened tube wall (23). The tube can be used both as a repair sleeve (21) (sleeve tube) for repairing defective heat exchanger tubes (7A) but also as a heat exchanger tube (7) which can easily be fitted into the tube bottom (9) of a steam generator (1). The invention also relates to a method for producing a tube (7 or 21) having an expansion area (25 or 25A, 25B).

Description

description

Pipe with a widening area and method for producing a pipe with a widening area

The invention relates to a tube, comprising a tube wall, a coating of the tube wall and at least one expansion area having a roughness, in which attachment to a component can be achieved by expanding the tube wall.

The invention also relates to a method for producing a tube with an expansion area.

The tube is particularly suitable for repairing a heat exchanger tube and / or for use as a heat exchanger tube, the heat exchanger tube being in particular a component of a nuclear steam generator.

Up to now, heat exchanger tubes have either been welded into the tube plate of a steam generator into bores made there or pressed into annular grooves in the interior of such holes in the tube plate by widening the inserted heat exchanger tube. In the latter case, the creation of numerous annular grooves in bores in the tube sheet, which is necessary, is particularly expensive and complex.

Steam generators can damage the heat exchanger tubes during their operation. The affected heat exchanger pipe can then either be closed with a pipe plug or repaired with a repair sleeve, a so-called sleeve pipe. For this purpose, the repair sleeve is inserted into the heat exchanger tube and fastened in the area of the damage at its two ends in the heat exchanger tube, for example by a rolling process, so that the damaged area is covered by the repair sleeve. The international patent application WO 90/06483 describes a pipe plug for closing a defective warm heat pipe, which is roughened in a widening area to a roughness depth of 0.05 to 0.2 mm. The roughened expansion area is in particular provided with a layer of deformable metal. In particular, a nickel material is provided as the deformable metal. The sealing effect and the holding force compared to the defective heat exchanger tube is achieved by the expansion of the expansion area. The sealing effect is improved by the nickel material.

German patent specification DE 44 33 501 C2 describes a repair sleeve for the repair of a heat exchanger tube, which has means at its ends on the outer jacket for fluid-tight connection to the heat exchanger tube. Such means are, for example, surveys or an additional sealing profile.

The sleeve tube described in British patent application GB 2 038 976 A has at its two ends a plurality of beads which are intended to produce a sealing contact between the outside of the sleeve tube and the inside of the heat exchanger tube to be repaired .

From the European patent application 0 446 841 AI a metallic sleeve for bridging a leakage point of a pipe is known, which can be applied to the inner wall surface of the pipe with the aid of the expansion technique. The sleeve has several components made of a shape-memory alloy on the jacket side, which form a seal between the sleeve and the tube when a predefinable temperature is reached. For another case in which the sleeve extends with its one end m the tube sheet of a steam generator, according to this European patent application a layer is applied to one of the expansion areas of the sleeve. The layer is profiled and has a large surface hardness. When expanding gang penetrates the profiling of the layer m the inner wall of the tube, so that a positive connection between the sleeve and tube is effected. This sleeve provided for installation in the tube sheet of a steam generator has the disadvantage that it is only complex and expensive to manufacture. The profiling must namely be introduced into the layer, which is complicated since the layer has a greater hardness than the inner wall of the tube. The profiling must therefore be introduced into the layer either by a tool that has an even greater hardness than the layer, or else it must be complicated when the layer is applied, which, according to the information in the European patent application, is preferably done by spraying a profiling m of the layer are generated.

The invention is therefore based on the object of specifying a tube with an expansion area which is suitable as a repair sleeve for the repair of a heat exchanger tube and which can be produced in a simpler and more cost-effective manner.

It is also an object of the invention to provide a method for producing a tube with an expansion area.

According to the invention the object related to a tube is achieved by such a tube, in which the roughness is given by roughening the tube wall in the expansion area and the coating is applied to the roughened tube wall, and in which the coating contains a deformable metal.

Such a tube can be used as a repair sleeve for repairing damage located at any point on the heat exchanger tube, that is to say not exclusively in the tube plate area of the steam generator. It can also be used as a heat exchanger tube in the tube sheet in a simple and inexpensive manner. Roughening is understood here and in the following to mean the type of unevenness, roughness or local thickening of the wall, regardless of whether the tube is first produced with a smooth tube wall and then roughened; or whether the tube was immediately produced in the roughened state during production. The roughening can be realized, for example, with a largely regular pattern, for example a pressed-in edge or the like. The roughening can also be realized only by a web and / or a groove, which are also produced, for example, when the tube is cast.

Because the roughness m of the tube wall is generated and the coating is only applied to the roughened tube wall, such a tube can be produced with little effort and little tool wear, since the applied coating itself does not necessarily have to be processed in order to increase the roughness produce. This is particularly advantageous if the coating is very hard.

The roughness is in particular on an outer surface of the pipe wall.

The roughness depth of the roughened expansion area is preferably 0.05 to 0.25 mm. Such a roughness depth can be implemented simply and quickly and meets the pressure resistance requirement for the common heat exchanger tubes in steam generators.

The roughness in the roughened expansion area is preferably formed by grooves which are in particular screwed into the tube or introduced by a non-cutting shaping process. This further simplifies the manufacture of a tube according to the invention. The grooves can have been created during screwing in, for example, in such a way that the material of the tube wall is partially erected, so that locally both a reduction in diameter and also immediately in addition to an increase in diameter compared to a non-roughened pipe. Both a notch and a bulge are thus produced immediately adjacent.

When the pipe is expanded in the roughened expansion area, the outer tips of the roughness first penetrate into the component. At a certain expansion pressure, the small area of the tips of the roughness creates a very large force there, so that the roughness of the tube penetrates well into the component and a position closure between the tube and the component is achieved. The coating of deformable metal supports the form fit between the pipe and the component and increases the tightness.

The coating can be applied without interruption, i.e. be applied as a coherent surface to the roughened pipe wall. However, the coating can also be applied only partially or in sections to the roughness.

A particularly advantageous embodiment of the tube provides that the coating is applied in such a way that its outer contour at least partially reflects the roughness of the tube wall.

The coating is preferably applied with a constant thickness. In this case, the outer surface profile of the coating largely reflects the roughness of the pipe wall in the expansion area, i.e. the outside of the layer has the same contour as the roughness of the pipe wall underneath. A coating with a constant thickness is - for example, by

Spraying, vapor deposition or electroplating - can be produced in a particularly simple manner.

According to a further preferred embodiment of the invention, the hardness of the coating is greater than the hardness of the component. This advantageously supports the penetration of the roughness into the component and both the Stigung the pipe and the sealing of the pipe against the component improved.

The hardness of the coating, expressed as Bπnell hardness, is preferably greater than 160.

The deformable metal is preferably a nickel material which, for example, consists essentially of nickel. Small amounts of less than a few percent are possible.

The nickel material is applied, for example, by plasma spraying.

A nickel material is particularly suitable as a deformable metal for coating the roughness, since nickel is both sufficiently deformable and hard enough to achieve a good sealing of the roughened tube wall against the component or a sufficient penetration of the roughened tube wall into the component. The nickel material can also be applied quickly and easily using plasma spraying.

The layer thickness of the nickel coating preferably has a value in the range from 10 μm and 100 μm, particularly preferably in the range from 40 μm to 60 μm.

Another advantageous embodiment provides that the tube has at least two spaced apart expansion areas.

Such a tube can preferably be attached to the component as a repair sleeve for bridging a damaged area of the component, which is in particular a heat exchanger tube. In other words, this means that such a tube can be used as a sleeve tube for repairing a heat exchanger tube. The damage site can be, for example, a leak and / or a wall thickness monitoring. According to a very particularly preferred embodiment, the tube can be attached as a heat exchanger tube to the component, which is in particular a tube plate of a steam generator. The tube can therefore not be used as a sleeve tube for a heat exchanger tube, but rather as a heat exchanger tube itself.

With a tube according to the invention, which is used as a heat exchanger tube, it is no longer necessary to make elaborate grooves in the bores in the tube plate of the steam generator.

The heat exchanger tube, into which a tube according to the invention is inserted as a repair sleeve for bridging a damaged area, or a heat exchanger tube which is a tube according to the invention, is preferably part of a nuclear steam generator.

The process-related object is achieved according to the invention in that a coating containing a deformable metal is applied to the roughened tube wall in the expansion area.

The coating is preferably applied in such a way that its outer contour at least partially reflects the roughness of the tube wall.

With the method according to the invention, a tube suitable as a repair sleeve or heat exchanger tube can be produced particularly easily and inexpensively.

With regard to the advantageous configurations of the coating and the roughening, what has been said above for the tube applies analogously.

Two exemplary embodiments of a pipe according to the invention are explained in more detail with reference to FIGS. 1 to 4. It shows: 1 shows a steam generator, in which it is indicated at which points the pipe according to the invention can preferably be installed,

2 shows a tube designed as a repair sleeve (sleeve tube) according to the invention,

3 shows a tube according to the invention for use as a heat exchanger tube installed in the tube sheet of the steam generator and

4 shows a detail from FIG. 2.

FIG. 1 shows a steam generator, generally designated 1, in a highly simplified and schematic manner. Hot water enters the steam generator 1 through the inlet opening 3 along the inflow direction 4 and out through the outlet opening 5 along the outflow direction 6. The inlet opening 3 and the outlet opening 4 are connected to one another via a multiplicity of U-shaped heat exchanger tubes 7, 7A. The heat exchanger tubes 7A are fastened and anchored in a gas-tight and liquid-tight manner in the tube sheet 9 of the steam generator. The inlet opening 3 and the outlet opening 5 are separated from one another by a partition wall 10.

II and III designate two locations in the steam generator 1, at which a tube according to the invention can preferably be used. Positions II and III are shown enlarged in the detail in FIGS. 2 and 3.

FIG. 2 shows a heat exchanger tube 7A, which has a damaged area 11 in the form of a weakening of the wall thickness far from the tube sheet 9. The damaged area can also be a leak. To bridge, ie seal, the damaged area 11, a tube 21 designed as a repair sleeve (sleeve tube) according to the invention is inserted into the heat exchanger tube 7A. The pipe . "„ ,,

WO 99/47843

Wall 23 is roughened in a first expansion area 25A and in a second expansion area 25B, which are arranged on both sides of the damaged area 11, so that a first roughness 26A or a second roughness 26B has arisen.

The heat exchanger tube 7A and the repair sleeve 21 are shown in one state before the repair sleeve 21 is expanded. When the repair sleeve 21 is widened, for example by a hydraulic device, the repair sleeve 21 in the widening areas 25A, 25B is enlarged in diameter from the inside, so that the roughness 26A, 26B formed by grooves 27 m the widening area, 25A, 25B m received the inner surface of the heat exchanger tube 7A. This also leads to a slight change in shape of the heat exchanger tube 7A, which is also not shown.

The roughness 26A, 26B in the expansion regions 25A, 25B is provided with a coating 31 made of nickel. After the repair sleeve 21 has been expanded, a form-fitting seal between the repair sleeve 21 and the heat exchanger tube 7A is thereby achieved, which also withstands the extreme conditions of a nuclear steam generator, in particular temperatures up to 350 ° C. and pressures of more than 7 MPa (70 bar). A weld seam connection between the heat exchanger tube 7A and the repair sleeve 21 is not required. Such a weld seam would disadvantageously lead to increased susceptibility to corrosion of the heat exchanger tube 7A.

The length 1 of the roughened expansion areas 25A, 25B is approximately 20 to 25 mm. The inner diameter 0 _{T of} the heat exchanger tube 7A is about 20 mm. The outer diameter 0_ of the repair sleeve 21 is adapted to the inner diameter 0 _: and is slightly smaller than this.

The roughness depth r of the roughness 26A, 26B with the expansion areas 25A, 25B is in the range 0.05 to 0.2 mm. The roughness depth r is the difference between a medium one Considered peak height and a medium groove depth. The roughness depth r is exaggerated in the figures for better explanation.

Figure 3 shows a tube according to the invention, which is used as a heat exchanger tube 7. and is fixed in the tube sheet 9 of the steam generator 1. The heat exchanger tube 7 has an expansion region 25 with a roughness 26. The roughness 26 is represented by grooves 27. A coating 31 made of nickel is applied to the roughness 26.

FIG. 3 also shows the pipe according to the invention, which here is a heat exchanger pipe 7, in an unexpanded state. During an expansion process, the roughness 26 hardened by the nickel coating 31 penetrates into the tube sheet 9 of the steam generator in the expansion region 25, so that a positional and positive connection is achieved. It is particularly advantageous that the tube sheet 9 does not have to be prepared by complex screwing in of annular grooves before the heat exchanger tube 7 is installed.

The statements made with respect to the exemplary embodiment shown in FIG. 2 apply analogously to the roughness depth r.

FIG. 4 shows a detail indicated in FIG. 2 in an enlarged representation. The heat exchanger tube 7 is in section, the repair sleeve 21 is uncut, i.e. viewed from the outside, shown. The tube wall 23 of the repair sleeve 21 has numerous grooves 27 in the second expansion area 25B, which are created by screwing in or similar shaping processes, such as e.g. Knurling. The grooves 27 are covered by a coating 31 of constant thickness, so that the surface of the coating 31 essentially follows the outer contour of the grooves in the tube wall 23.

Claims

claims

1. Pipe (7 or 21) comprising a pipe wall (23), a coating (31) of the pipe wall (23) and at least one expansion area (25 or 25A, 25B) having a roughness (26 or 26A, 26B) , in which attachment to a component (9 or 7A) can be achieved by widening the pipe wall (23), characterized in that the roughness (26 or 26A, 26B) is roughened by the pipe wall (23) in the widening area (25 or 25A, 25B) and the coating (31) is applied to the roughened tube wall (23), and that the coating (31) contains a deformable metal.

2. Pipe (7 or 21) according to claim 1, so that the roughness (r) of the roughened expansion area (25 or 25A, 25B) is 0.05 to 0.25 mm.

3. Pipe (7 or 21) according to claim 1 or 2, d a d u r c h g e k e n n z e i c h n e t that the roughened expansion area (25 or 25A, 25B) is formed by grooves (27).

4. Pipe (7 or 21) according to claim 3, d a d u r c h g e k e n n z e i c h n e t that the grooves (27) are screwed in or introduced by a non-cutting shaping process.

5. Pipe (7 or 21) according to one of claims 1 to 4, d a d u r c h g e k e n n z e i c h n e t that the coating (31) is applied without interruption.

6. Pipe (7 or 21) according to one of claims 1 to 5, characterized in that the coating (31) is applied such that its outer contour at least partially reflects the roughness (26 or 26A, 26B) of the tube wall (23).

7. Pipe (7 or 21) according to one of claims 1 to 6, d a d u r c h g e k e n n z e i c h n e t that the coating (31) is applied with a constant thickness.

8. Pipe (7 or 21) according to one of claims 1 to 7, d a d u r c h g e k e n n z e i c h n e t that the deformable metal is a nickel material.

9. tube (7 or 21) according to claim 8, d a d u r c h g e k e n n z e i c h n e t that the nickel material consists essentially of nickel.

10. Pipe (7 or 21) according to claim 8 or 9, d a d u r c h g e k e n n z e i c h n e t that the nickel material is applied by plasma spraying.

11. Pipe (7 or 21) according to one of claims 1 to 10, characterized in that the hardness of the coating (31) greater than the hardness of the component (9th

12. Pipe (7 or 21) according to claim 11, d a d u r c h g e k e n n z e i c h n e t that the hardness expressed as Brinell hardness is greater than 160.

13. Pipe (21) according to one of claims 1 to 12, g e k e n n z e i c h n e t d u r c h at least two spaced expansion areas (25A, 25B).

14. Pipe (21) according to claim 13, characterized in that it as a repair sleeve (21) for bridging a damaged area (11) of the component (7A), which is in particular a heat exchanger tube (7A), can be attached to the component (7A) .

15. Pipe (7) according to one of claims 1 to 13, d a d u r c h g e k e n n z e i c h n e t that it as a heat exchanger tube (7) on the component (9), which is in particular a tube sheet (9) of a steam generator (1), can be fastened.

16. Pipe (7 or 21) according to claim 14 or 15, so that the heat exchanger tube (7, 7A) is part of a nuclear steam generator (1).

17. Method for producing a tube (7 or 21) with an expansion area (25 or 25A, 25B), wherein in the expansion area (25 or 25A, 25B) on the roughened tube wall (23) a coating containing a deformable metal ( 31) is applied.

18. The method according to claim 17, so that the coating (31) is applied in such a way that its outer contour at least partially reflects the roughness (26 or 26A, 26B) of the tube wall (23).