JPH0242588B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a method for assembling a Ti-Al double pipe and a Ti tube sheet, and in particular, the present invention relates to a method for assembling a Ti-Al double pipe and a Ti tube sheet, and particularly,
This invention relates to a method for effectively assembling a double tube, which is made by crimping a Ti inner tube made of Ti (titanium) material onto the inner surface of an Al outer tube, to a Ti tube plate of a target device such as a condenser.

Conventionally, as a heat transfer tube in a condenser or heat exchanger, a corrosion-resistant, thin-walled Ti tube is used as the inner tube, while a tube made of a metal material different from Ti, that is, an Al material, is used as the outer tube. Consideration has been given to using a Ti-Al double tube, a so-called Ti-lined double tube, in which the Ti tube is crimped onto the inner surface of an Al outer tube. In the case of a condenser using such double tubes, the characteristics of the constituent materials, namely the high heat transfer performance when condensing the working fluid in the finned Al tube (outer tube), and the thin-walled Ti tube (inner tube) are important. Taking advantage of the characteristics such as high seawater corrosion resistance, the inside of the double pipe is filled with seawater or a fluid (cooling fluid) with corrosive properties equivalent to seawater, and the outside surface of the pipe is filled with seawater, taking into consideration the problem of corrosion of Al material. A heat exchange configuration is adopted in which a condensable fluid (high temperature fluid) that does not need to be heated is allowed to flow. Specifically, condensers using this double pipe include condensers for ocean thermal power generation using ammonia and fluorocarbons as condensable working fluids, vertical fluorocarbon turbines,
Examples include capacitors and capacitors for LNG liquefaction equipment.

By the way, such a double pipe is generally installed in the condenser by being attached to a tube plate that partitions the inside of the condenser, and the seawater introduced into the room partitioned by the pipe is A corrosive cooling fluid, such as, is allowed to flow through the double tube tubes attached to the tube sheet. Since the tube sheet is also exposed to the corrosive cooling fluid, it is desirable to form the tube sheet from Ti material, but when such a Ti tube sheet is used, There are some problems inherent in the assembly between it and the Ti-Al double tube that need to be solved. That is, such a double pipe and
When assembling with a Ti tube sheet, conventional methods of joining tubes and tube sheets, such as mechanical tube expansion and seal welding, can be applied, but each method has various drawbacks. is inherent.

In other words, when assembling a Ti-Al double pipe and a Ti tube plate using a mechanical tube expansion method,
Since the end of the double tube is simply expanded mechanically and crimped onto the inner surface of the mounting hole in the tube sheet, the assembly is not leak-tight and has good heat conductivity. In addition to the problem of low performance and unreliability in terms of installation strength, the Al material constituting the outer pipe of such a double pipe is exposed at the end surface of the double pipe, which causes damage to the inside of the double pipe. There is a problem of corrosion caused by corrosive fluids that are passed through the
For this reason, there are problems such as the need to apply an appropriate anti-corrosion coating to the end surface of such a double pipe and to attach a protective cap to cover the end surface of the pipe.

Seal welding, in other words, circumferential welding, in which the Ti-Al double tube is inserted into the mounting hole of the Ti tube sheet, and then the end of the double tube is welded to the Ti tube sheet along the circumferential direction. In the case of welding, as a welding rod
When a Ti welding rod is used, a weak Al-Ti alloy layer is formed in the weld, causing cracks and making it impossible to obtain a sound weld. For this reason, it is necessary to use a welding rod made of Al, which is the constituent material of the outer tube, and as a result, the welded part has poor corrosion resistance.
When Al materials are fused together, there is a problem in that they cause severe corrosion. In addition, if a protective cap or the like is provided to cover the welded part in order to prevent corrosion of the welded part, the number of assembly steps will increase, and the work will also become troublesome, leading to increased costs. It also becomes.

The present invention has been made against this background, and its purpose is to provide an advantageous method for assembling a Ti-Al double pipe and a Ti tube sheet. Another objective is to obtain a joint that is leak-tight and has improved thermal conductivity, is highly reliable in terms of installation strength, and has no corrosion resistance. An object of the present invention is to provide an assembly method that can provide a problem-free attachment part.

In order to achieve this object, the present invention provides an assembly of a Ti-Al double tube to a Ti tube plate, which is made by crimping a Ti inner tube made of a Ti material onto the inner surface of an Al outer tube made of an Al material. In the attaching method, (a) the Al outer tube constituting the Ti-Al double tube is made shorter than the Ti inner tube by a predetermined length of ₁ minute from the tube end, and the Ti
ensuring that only the inner tube is present at the tube end;
(b) A Ti collar made of Ti material is fitted onto the outer periphery of the end of the Ti-Al double pipe, and is inserted over a predetermined length l ₂ (however, l ₂ > l ₁ ) from the pipe end. , a step of covering the outer peripheral surface of the pipe end of the double pipe with the Ti collar; (c)
The end of the Ti collar opposite to the tube end side of the Ti-Al double tube, and the Al outer tube of the Ti-Al double tube,
fixing the Ti collar to the Ti-Al double tube by fusion welding; and (d) attaching the Ti-Al double tube to which the Ti collar is fixed in a predetermined manner to the Ti tube sheet. (e) the Ti collar located at the end of the Ti-Al double pipe and the end of the Ti inner pipe;
The structure includes the step of melt-welding the Ti tube plate and fixing them together.

That is, according to the present invention, the Al outer tube portion at the tip of the Ti-Al double tube is made shorter by a predetermined length: l ₁ than the inner Ti inner tube, and a Ti collar is provided on the outer periphery. By being forced to place
Since the tip of such a double tube is made only of Ti material, it is possible to similarly perform fusion welding on a Ti tube plate made of Ti material to a normal Ti material, and furthermore, this makes it possible to Therefore, a sound molten weld can be obtained without forming an alloy layer with other metals in the weld, and a leak-tight assembly structure can be achieved. The conductivity was also improved, and the reliability in terms of assembly strength was also significantly improved.

In addition, since the welded part formed between the end of the Ti-Al double pipe and the Ti tube plate by such fusion welding is substantially made of Ti,
Even if it is exposed to corrosive cooling fluids such as seawater, problems such as corrosion rarely occur, and for this reason conventional anti-corrosion coatings or protective caps are applied to such welds. There is no need to take any measures such as forcing the driver to wear a

Hereinafter, the structure of the present invention will be explained in more detail with reference to drawings showing embodiments of the present invention.

First, FIG. 1 is a process diagram showing one embodiment of the method of the present invention, in which 2 is a Ti-Al double tube, and the double tube 2 is made of Al material (Al or its alloy). ) and a Ti inner tube 6 made of a Ti material (Ti or its alloy), and the Ti inner tube 6 is crimped onto the inner surface of the Al outer tube 4 in the same manner as in the past. It is being In addition,
When the intended double pipe 2 is used as a condensing pipe, the Al outer pipe 4 desirably has fins on its outer peripheral surface. As shown in the figure, a plurality of fins 8 of a predetermined height are integrally provided parallel to each other in the tube axis direction. Of course, this Finn 8 takes
It is also possible to provide one or more in the circumferential direction of the Al outer tube 4.

By the way, Ti-Al double pipe 2 with such a configuration
In the present invention, this Al outer tube 4 is made shorter than the Ti inner tube 6 by a predetermined length _l1 from the tube end. As a method for shortening this Al outer tube 4,
In general, a method of cutting off the length of the Al outer tube 4 by ₁ minute is effectively adopted, but other methods such as Ti-Al
When manufacturing the double tube 2, it is also possible to adopt a method in which the Ti inner tube 6 is made to protrude beyond the Al outer tube 4 by a length of _l1 and then crimped.

In addition, the Al outer tube 4 shortened in this way has
Machining is performed to remove a predetermined length _l4 of the outer circumferential surface from the end. Particularly, such removal of the outer peripheral surface is effective when the Al outer tube 4 is provided with fins 8. In such a case, the Al outer tube 4 is removed so as to include at least the fins 8. It will be removed on the outer circumferential surface of the Of course, this removal of the outer peripheral surface of the Al outer tube 4 also serves as a part for receiving the Ti collar to be fitted, as will be described later.On the other hand, the Ti collar 10 is a cylindrical body made of Ti material. As shown in the figure, a chamfered portion 12 is formed at one end to provide a predetermined groove shape for welding with the Al outer tube 4. A V-shaped groove is provided between the chamfered portion 14 provided at the end of the outer circumferential surface removed portion of No. 4. Note that the groove shape is not limited to the V-shape, and various other shapes may be selected as appropriate. Furthermore, the axial length _l2 of the Ti collar 10 is larger than the shortened length _l1 of the Al outer tube 4.

Therefore, when the Ti collar 10 is inserted into the outer circumference of the Ti-Al double tube 2 from its end, the double tube 2 is
The outer peripheral surface of the Al outer tube 4 is covered over the shortened portion (l ₁ ) and the removed portion (l ₄ ) of the outer peripheral surface thereof. In addition, here, the
The end face of the Ti collar 10 is made to approximately match the end face of the Ti inner pipe 6 of the double pipe 2;
The end of the Ti collar 10 is made to protrude a predetermined amount outward in the tube axis direction from the Ti inner tube 6, in other words, the length of l ₂ is
If the length is set to be a certain amount larger than the total length of l ₁ and l ₄ , such a protruding portion of the Ti collar 10 can be used as filler material that is effective during fusion welding with the Ti tube sheet, which will be described later. It is possible.

In the case of the double pipe 2 in which the Ti collar 10 is fitted on the outer periphery in this way, such
At the end of the Ti collar 10 opposite to the tube end side of the double tube, between the aluminum outer tube 4 of the double tube 2, in the illustrated example, the chamfered portion 12 of the Ti collar 10
A predetermined fusion welding is performed between the chamfered portion 14 of the Al outer tube 4 and the Ti collar 10 is
is fixed to the Ti-Al double pipe 2 at a welded portion 16.

In addition, when melt welding the Al outer tube 4 and the Ti collar 10, especially the butt portions 12,
14 includes appropriate pretreatment, such as acetone degreasing,
The surface of the welded part is properly prepared by cleaning the welded part by chemical cleaning or mechanical polishing.

In addition, in the present invention, such an Al outer tube 4 and
The method of welding with the Ti collar 10 is, in particular, using argon as the shielding gas and Al or its alloys, phosphorous copper solder, or 20% as the filler metal.
% or more of Al (silver content is 80% or less), while direct current positive polarity power supply (DCSP)
Alternatively, a TIG arc powered by an alternating current power source (AC) is used as a heat source, whereby the Al outer tube 4
Only the side parts and filler metal are melted, and the Al
A method of joining these two materials without substantially causing melting of the Ti collar 10 side portion that is joined to the outer tube 4 will be suitably adopted.

However, by adopting such a predetermined welding method, it is possible to effectively join dissimilar metals such as Al material and Ti material, and there are no inherent problems such as weld cracking or poor fusion in the welded part 16. This is because a healthy joint can be obtained. In addition, when forming the final layer of the welded part 16 after adopting such a predetermined fusion welding method, finishing may be performed without a filler metal using an AC/TIG arc as a heat source, if necessary. It may happen.

Next, the Ti-Al double tube 2 with the Ti collar 10 fixed to the tube end portion in this manner is inserted into the mounting hole 20 of a predetermined Ti tube plate 18 made of Ti material, as shown in the figure. After being placed at a predetermined mounting position, the Ti collar 10 located at the pipe end of the double pipe 2 and the end of the Ti inner pipe 6,
Melt welding is performed between the Ti tube plate 18 and the peripheral edge of the mounting hole 20, so that they are integrally joined. The welding operation for joining the double tube 2 and the Ti tube plate 18 is generally performed using an inert gas such as argon as a shielding gas, and a direct current positive polarity (DCSP)/TIG arc as a heat source. be done,
Ordinary fusion welding methods are used for titanium materials, and in some cases, titanium is not used at all, and in some cases, filler metals made of Ti or its alloys are used. .
In addition, when performing such fusion welding, the above-mentioned
As in the case of welding the Al outer tube 4 and the Ti collar 10, appropriate pretreatment is appropriately performed on the welding location.

In this way, the arc welding method conventionally used for joining Ti materials can be suitably used to attach the double tube 2 to the Ti tube plate 18.
Moreover, it can be easily welded in a factory or on site. At this time, a groove is suitably provided on the end face of the double pipe 2, in other words, on the end face of the Ti collar 10 and the welding area of the tube plate 18 (periphery of the mounting hole 20) to adjust the penetration shape. is effective, and in the illustrated example, a groove 22 is provided along the periphery of the mounting hole 20 of the Ti tube sheet 18, and is used as a predetermined groove. The peripheral edge of the mounting hole 20, the Ti collar 10 at the tip of the double tube 2, and the Ti inner tube 6 are welded by arc welding, and the tube end of the double tube 2 is attached to the Ti tube plate. 18 is completely circumferentially fused welded.

Note that, prior to welding the double tube 2 and the Ti tube plate 18, a suitable diffusion operation is applied to the tip of the double tube 2 inserted into the mounting hole 20 of the Ti tube plate 18. It is also effective to press the tip of the double pipe 2 onto the inner surface of the mounting hole 20.

In this way, the Ti-Al double tube 2
In the Ti inner tube 6 and Ti collar 10 portion made of only Ti material at the tip, the Ti tube plate 18
Since the welded portion 24 is welded to and assembled with Ti, the welded portion 24 is substantially made only of Ti, and therefore the welded portion exposed to corrosive cooling fluid is not as fragile as in the past. No alloy layer is formed at all, and therefore an extremely sound weld 24 can be obtained. Moreover, since the double tube 2 and the Ti tube plate 18 are attached by welding, their attachment is not only leak-tight, but also has improved thermal conductivity, and also has a strong attachment strength. Furthermore, since the welded portion 24 is made of Ti, the durability against corrosion of the welded portion can be effectively improved.

In addition, in the process according to the present invention, Al
The shortened length l ₁ of the outer tube 4 with respect to the Ti inner tube 6 is the length of the Al
Although the Al material of the outer tube 4 is selected so as not to fuse with the Ti material of the welded portion 24, the length is generally about 10 mm.

In addition, the length of the outer peripheral surface of the Al outer tube 4, generally the length of the fins 8 removed: _l4 , takes into account the shortened length of the Al outer tube 4: _l1 and the thickness of the Ti tube sheet 18. It will be set as follows. For example, in the illustrated example, the fusion welded part 1 between the Al outer tube 4 and the Ti collar 10 is
6 is selected to be located at a location slightly away from the end of the Ti tube sheet 18, but this is not necessarily the case; Even if it is located inside the hole 20, there is no problem.

Furthermore, the length of the Ti collar 10: l ₂ is generally
It is selected based on the total length of the removed portion of the outer peripheral surface of the Al outer tube 4: l ₄ and its shortened length: l ₄ , but as mentioned above, they do not necessarily have to be equal; for example, By increasing the length of the collar 10 by a predetermined amount, the collar ₁₀ is made to protrude from the Ti tube sheet 18,
It is also possible to use it as a filler metal when forming the weld portion 24.

Further, in another embodiment of the present invention shown in FIG. 3, unlike the straight collar 10 used in the above embodiment, a Ti collar is used, and the inner diameter is a predetermined length: l ₃ minutes from the end. was made smaller by
In other words, a major feature is that the collar 26 with a valve is used, the wall thickness of which is increased by _l3 , and a step is provided on the inner diameter.

That is, as shown in FIG. 3, the bulb (thick) portion 28 of the bulb collar 26 is
It is inserted into the Ti--Al double tube 2 so as to be located at the portion of the Al outer tube 4 that has been shortened by the _l1 length. Therefore, this valve part 2
8 is located in the shortened part of the Al outer tube 4, the length of the valve part 28: l ₃ is the Al
The shortened length of the outer tube 4 must be smaller than l ₁ , and generally there is a predetermined length between the end face of the shortened Al outer tube 4 and the valve portion 28 of the valved collar 26: l ₅ A void 30 is formed. In other words, a gap is formed such that l ₁ −l ₃ =l ₅ .

In this way, the valved collar 26 is used as the Ti collar, and the Ti
By filling the gap formed between the inner tube 6 and the Ti collar with the valve portion 28, welding between the double tube 2 and the Ti tube plate 18 can be performed more effectively. This makes it possible to further improve the properties of the molten welded portion 24 formed. In particular, the use of such a valved collar 26 is effective when the Ti inner tube 6 is thin and the gap formed between the Ti collar to be fitted and the Ti inner tube 6 is large. Extremely effective.

Note that the length of the valve portion 28 of the valved collar 26: _l3 is selected by taking into consideration the length of the gap formed between it and the tube end of the Al outer tube 4: _l5 . . This length: l ₅ gap 30, when using the valved collar 26 as shown in the figure,
Al when inserted into the tube plate 18 and expanded
This gap 30 is intended to absorb the amount of deformation of the outer tube 4, and such a gap 30 is appropriately provided as necessary.

In addition, in the embodiment shown in FIG.
In the collar 26 with a bulb as a collar, the collar portion and the bulb portion 28 are formed integrally, but instead of this, the bulb portion and the collar portion are made separate and correspond to such a bulb portion.
Insert the Ti sleeve or Ti insert into the Ti inner tube 6.
It is also possible to fit it into the gap formed between the Ti collar and the Ti collar.

Although several specific examples of the present invention have been described above, the present invention is not to be construed as being limited only to such specific examples, and the present invention for,
Various modifications, modifications, and improvements can be made based on the knowledge of those skilled in the art, and the present invention includes such embodiments;
It goes without saying.

[Brief explanation of the drawing]

FIG. 1 is a process diagram showing an embodiment of the assembly method according to the present invention, and FIG.
3 is a cross-sectional view, and FIG. 3 is a process explanatory diagram showing another embodiment of the present invention. 2: Ti-Al double tube, 4: Al outer tube, 6: Ti inner tube, 8: Fin, 10: Ti collar, 12,1
4: Chamfered part, 16: Welded part, 18: Ti tube sheet,
20: Mounting hole, 22: Groove, 24: Welded part, 26:
Collar with valve, 28: valve.

Claims (1)

[Claims] 1. A Ti-Al double tube made by crimping a Ti inner tube made of a Ti material onto the inner surface of an Al outer tube made of an Al material.
As for the assembly method to the tube sheet, the Al outer tube constituting such a Ti-Al double tube is shorter than the Ti inner tube by a predetermined length: ₁ minute from the tube end,
A step in which only the Ti inner tube is present at the tube end, and a Ti collar made of Ti material is inserted around the outer periphery of the tube end portion of the Ti-Al double tube, and a predetermined length is inserted from the tube end. : covering the outer circumferential surface of the tube end of the double tube with the Ti collar over l ₂ (where l ₂ >l ₁ ), and covering the tube end of the Ti-Al double tube of the Ti collar with the Ti collar. The end opposite to the side and the Al outer tube of the Ti-Al double tube,
fixing the Ti collar to the Ti-Al double tube by fusion welding; and fixing the Ti-Al double tube to which the Ti collar is fixed,
a step of fitting the Ti tube plate into a predetermined mounting hole and arranging it at the mounting position; 1. A method for assembling a Ti-Al double pipe and a Ti tube sheet, the method comprising the step of melt welding the tube sheet and fixing them integrally. 2. The Ti collar is a valved collar whose inner diameter is reduced and thickened by a predetermined length of l ₃ minutes from the end (where l ₃ < l ₁ ), and the valve portion is the same as the _one above. 2. The assembly method according to claim 1, wherein the Ti--Al double tube is inserted into the Ti-Al double tube so as to be positioned in the shortened Al outer tube portion. 3. The area formed by inserting the Ti collar
2. The assembly method according to claim 1, wherein a sleeve made of Ti material is inserted into the gap between the Ti collar and the Ti inner tube at the end of the Ti-Al double tube. 4 The outer peripheral surface of the Al outer tube constituting the Ti-Al double tube is a predetermined length from the shortened end: l ₄
Claim 1, which has been removed,
The assembly method according to any one of Items 3 to 3. 5. The Al outer tube constituting the Ti-Al double tube has at least one fin extending in the tube axis direction or tube circumferential direction on its outer surface, and includes at least such fin, and the Al outer tube 5. The assembly method according to claim 4, wherein the outer circumferential surface of is removed. 6 Is the length of the Ti collar (l ₂ ) the same as the total length (l ₁ + l ₄ ) of the shortened length of the Al outer tube (l ₁ ) and the removed length of the outer peripheral surface of the Al outer tube (l ₄ )? , or a certain amount larger than that. 7. While the fusion welding of the Ti collar and the Al outer tube uses argon as the shielding gas and uses Al or its alloy, phosphorous copper solder, or a silver alloy containing 20% or more Al as the filler material, This is carried out using a TIG arc from a DC positive polarity power source or an AC power source as a heat source, thereby melting only the Al outer tube portion and the filler metal, and melting the Ti collar side portion that is joined to the outer tube. 2. The assembly method according to claim 1, wherein the two materials are joined without substantially causing the above. 8 After fitting the Ti-Al double pipe into the mounting hole of the Ti tube sheet, expanding the double pipe and crimping it into the mounting hole, and then performing the welding to the Ti tube sheet. An assembly method according to claim 1. 9. A predetermined groove is provided at the peripheral edge of the mounting hole of the Ti tube plate, and the above-mentioned tube is fitted into the mounting hole.
2. The assembly method according to claim 1, wherein the Ti collar at the tip of the Ti-Al double tube and the Ti inner tube portion are welded to the groove to integrally fix them. 10 Claim 1, wherein the fusion welding for fixing the Ti-Al double tube to the Ti tube sheet is performed by a direct current positive polarity TIG arc welding method using an inert gas as a shielding gas. Assembly method described in section.