JP3134691B2 - Pipe connection structure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pipe connecting structure in which pipes made of different materials are welded and connected to each other in a pipe through which a corrosive fluid flows.

[0002]

2. Description of the Related Art Generally, when storing a high-level radioactive solution generated in a spent nuclear fuel reprocessing plant or the like in a storage tank, the radioactive solution is introduced into the storage tank through a pipe made of stainless steel or the like. I have to. In this case, the stainless steel pipe is fixed to a nozzle formed in the stainless steel storage tank by butt welding.

[0003] By the way, the radioactive solution becomes highly corrosive when the temperature is high, and the pipe through which such radioactive solution flows must be made of a material having excellent corrosion resistance such as zirconium. Dissimilar metal pipes cannot be welded to the liquid storage tank. Therefore, it is conceivable to connect the pipe to the liquid storage tank through a dissimilar material joint. Dissimilar material joints are formed by joining different materials to each other by atomic diffusion and then formed into a joint.One material of the dissimilar material joint is made of stainless steel and welded to a liquid storage tank, and the other material is made of zirconium. The connection between the zirconium tube and the stainless steel storage tank becomes possible.

[0004]

However, since the joints of different materials have not been officially confirmed in terms of corrosion resistance and the like depending on the use conditions, there are many cases where the use is restricted. For this reason, there has been a strong demand for a pipe connection structure that can connect pipes of different materials and use them without any problem.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a pipe connection structure which can be connected without restriction to the material of the pipe and used without any problem.

[0006]

According to a first aspect of the present invention, there is provided a pipe connecting structure comprising a pipe made of a material having a high corrosion resistance and a fluid flowing therethrough, and the pipe having the fluid flowing from the pipe. A connection structure for connecting a member made of a material having a lower corrosion resistance than that of the member, wherein one end of the member is formed of a material equivalent to the same member and the other end is formed of the pipe. A dissimilar joint made of a material equivalent to the above is welded and fixed, and one end of a connecting pipe made of the same material as the other end is welded and fixed to the other end of the dissimilar joint. The connection pipe is welded and fixed to the other end of the connection pipe, and the connection pipe has a pipe part whose one end and the other end are respectively arranged on the inner peripheral side and the outside of the dissimilar material joint. The outer peripheral part is welded to the opening edge of the dissimilar material joint, and One end, the opening edge portion is characterized in that a sufficient length positioned on the downstream side of the above dissimilar material joint.

According to a second aspect of the present invention, the connecting pipe has a second pipe extending radially outward from an outer periphery of the pipe, and an edge of the second pipe has an edge. A gap is provided in a pipe between the pipe portion and the dissimilar material joint by being welded to an opening edge of the dissimilar material joint.

[0008]

In the pipe connecting structure according to the first aspect, the liquid flowing through the pipe flows into the downstream member through the connecting pipe, but the opening edge of the pipe portion of the connecting pipe is larger than that of the dissimilar joint. Since it is located on the downstream side, the liquid does not come into contact with the dissimilar material joint. Therefore, the corrosion resistance of the dissimilar joint to the liquid does not matter.

Further, in the pipe connecting structure according to the second aspect, since a gap is provided in the pipe between the pipe portion and the dissimilar material joint, the liquid permeates between the pipe portion and the dissimilar material joint by capillary action. There is no such thing. Therefore, contact between the dissimilar material joint and the liquid is reliably prevented.

[0010]

【Example】

A. First Embodiment (1) Configuration of the Embodiment Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. The first embodiment is an example in which the present invention is applied to an annular tank for storing a radioactive solution. FIG. 1 is a side sectional view showing a storage tank main body 1 of an annular tank, and FIG. 2 is a plan view. . In FIG. 1, reference numeral 2 denotes a base plate. The base plate 2 has a ring shape, and is fixed to a foundation (not shown) by bolts or the like by protruding in a flange shape from the inner and outer peripheries of the storage tank main body 1. A lower ring 3 is fixed to an upper surface of the base plate 2. On the upper surface of the lower ring 3, a concave portion 3a extending over the entire circumference is formed. The bottom surface of the recess 3a
In FIG. 1, it is inclined so as to have a downward slope from the left side to the right side. In addition, a drain port (not shown) is disposed at the lowest position on the bottom surface of the concave portion 3a. In addition, the code | symbol 60 in a figure is a 1st lower flat plate, 61 is a 2nd lower flat plate,
The first lower plate 60 is attached to the base plate 2 by bolts, and the second lower plate 61 is
At the same time, they are attached to a foundation (not shown) by bolts.

The upper edge of the lower ring 3 has an inner wall 4
The liquid storage section outer wall 5 is fixed, and the high-level radioactive fluid is stored in the liquid storage section 6 formed by the lower ring 3, the liquid storage section inner wall 4, and the liquid storage section outer wall 5. The upper end opening of the liquid storage unit 6 is concealed by an upper ring (member) 7 fixed to the upper edges of the inner wall and the outer walls 4 and 5 of the storage unit.

On the lower surface of the upper ring 7, there are formed two protruding edges 7a, 7b extending over the entire periphery thereof, and the protruding edges 7a, 7b are formed on the upper edge of the inner wall 4 and the outer wall 5 of the liquid storage section. It is fixed to the part by welding. Also, the upper ring 7
Are formed with holes 10 which penetrate in the vertical direction and are arranged in the circumferential direction. Around the hole 10, a cylindrical upper nozzle 12 and a lower nozzle 13 are formed. An outer pipe 15 for low temperature is fixed to the upper nozzle 12 by butt welding, and an inner pipe 16 is fixed to the lower nozzle 13 by butt welding. FIG. 4 shows an example in which the internal piping 16 is provided.
6 and therefore the lower nozzle 1 for fixing it
There are three places.

The upper ring 7 is provided with one hole 20 having an inner diameter larger than that of the hole 10, and an opening at the upper end of the hole 20 is formed with a convex edge 22 having a cylindrical shape. A dissimilar material joint 25 is fixed to the protruding edge portion 22 by butt welding. The dissimilar material joint 25 is formed by joining materials made of two types of materials by diffusion bonding, explosive bonding, hot rolling bonding, or the like, and processing the cylindrical material. In this example,
The dissimilar material joint 25 has a lower end 25a made of stainless steel.
And an upper end 25b made of zirconium. It should be noted that a different material can be interposed between the two types of materials. For example, tantalum can be interposed between stainless steel and zirconium.

The lower end 25a of the dissimilar material joint 25 is made of stainless steel because the upper ring 7 is also made of stainless steel, so that both can be welded and fixed.
The reason why the upper end portion 25b is made of zirconium is to enable welding and fixing to the reducer (connection tube) 30. As shown in FIG. 3, the reducer 30 includes a cylindrical small-diameter tube (tube) 31 and a large-diameter tube 32 extending axially in a skirt shape from the outer periphery of the small-diameter tube 31. ing. The reducer 30 is made of zirconium, and its large-diameter pipe portion 32 is
5 is fixed to the upper end portion 25b by butt welding.

A high temperature external pipe (pipe) 33 made of zirconium is connected to the upper end of the small diameter pipe section 31 of the reducer 30. The radioactive solution having a higher temperature than the low-temperature external pipe 15 is allowed to flow through the high-temperature external pipe 33. A radioactive solution having a high temperature is highly corrosive, and therefore, zirconium, which has better corrosion resistance than stainless steel, is used as a material for the high-temperature external piping 33. In addition, the lower end of the small diameter pipe portion 31 is
It extends below the dissimilar material joint 25. As a result, the radioactive solution flowing through the small-diameter tube portion 31 is dissimilar to the dissimilar joint 2.
5 is injected into the liquid storage part 6 without contacting the same.

Next, a ring-shaped first upper flat plate 40 and a second upper flat plate 41 are attached to the inner and outer peripheral sides of the upper surface of the upper plate 7 by bolts or the like. The inner peripheral edge of the lower surface of the first upper flat plate 40 and the first lower flat plate 60
, A stainless steel plate 52 forming an outer shell inside the liquid storage tank main body 1 is fixed by welding. A neutron moderator 50 is attached to the outer peripheral surface of the stainless steel plate 52. As a material of the neutron moderator 50, for example,
Any material containing sufficient hydrogen and carbon, such as resins such as high-density polyethylene and silicone resin, concrete and carbon blocks, can be used.

A neutron absorber 43 is attached to the outer peripheral surface of the neutron moderator 50. As a material of the neutron absorber 43, cadmium, boron, gadolinium, samarium, europium, or the like may be used alone, or a compound of such a substance, or a composite of such a substance or a compound and another substance may be used. Can be. further,
The neutron-absorbing substance as described above can be mixed with, for example, plastic to form a plate-like composite.

Next, a stainless steel plate 58 constituting an outer shell of the liquid storage tank body 1 is fixed to the outer peripheral edge of the lower surface of the second upper flat plate 41 and the second lower flat plate 61 by welding. . A neutron moderator 56 is attached to the inner peripheral surface of the stainless steel plate 58, and a neutron absorber 54 is attached to the inner peripheral surface of the neutron moderator 56. The neutron moderator 56 and the neutron absorber 54 are made of the same material as the neutron moderator 50 and the neutron absorber 43.

(2) Operation and Effect of First Embodiment In the annular tank having the above-described structure, the radioactive solution flowing through the low-temperature external pipe 15 is stored through the hole 10 of the upper plate 7 and the internal pipe 16. It is poured into the liquid tank 6. The radioactive solution flowing through the high-temperature external pipe 33 is injected into the liquid storage tank 6 through the small-diameter pipe section 31 of the reducer 30.
At this time, since the small diameter pipe portion 31 extends to the lower side of the dissimilar material joint 25, the radioactive solution is injected into the liquid storage unit 6 without contacting the dissimilar material joint 25. The radioactive solution flowing through the high-temperature external pipe 33 has a high temperature and is highly corrosive on the upstream side, but is cooled and less corrosive at the time of being injected into the circular liquid storage tank 6. Therefore, there is no problem such as corrosion of the liquid storage tank 6.

In the annular bath having the above structure, since the dissimilar joint 25 is interposed between the protruding edge 22 of the upper plate 7 and the reducer 30, the material of the dissimilar joint 25 and the material of the reducer 30 are heated to a high temperature. By using the same zirconium as the material of the external piping 33, the parts can be welded and fixed. In addition, since the radioactive liquid flowing through the small-diameter tube portion 31 does not contact the dissimilar material joint 25,
There is no need to consider the corrosion of the dissimilar joint 25 due to the radioactive liquid, and the annular tank can be used safely.

B. Second Embodiment FIG. 5 shows an example in which the present invention is applied to a glove box, and FIG. 5 is a side sectional view thereof. In the second embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted. In the figure, reference numeral 50 denotes a casing, and the inside of the casing 50 is completely shielded from the outside. A plurality of holes 51 (only one is shown in the figure) are formed in the casing 50, and a lid 52 is detachably attached to each of the holes 51. The hole 51 has a glove 53
Is fixed, and a hand is inserted from the outside into the glove 53 to perform various operations in the casing 50.

Next, a pipe 5 is provided on the upper wall of the casing 50.
4 are penetrated. The pipe 54 is made of stainless steel, and the upper end is welded and fixed to the dissimilar joint 25. A reducer 30 is fixedly welded to the upper end of the dissimilar joint 25 in the same manner as in the first embodiment.
A pipe 55 made of zirconium is fixedly welded to the upper end of the tube. On the other hand, the lower end of the pipe 54 is connected to a container (not shown) arranged in the casing 50. Although not shown, the container is filled with the liquid in the casing 50.
A pipe for discharging to the outside is connected.

In the glove box configured as described above,
A corrosive solution such as a radioactive solution is passed through the pipe 55,
The corrosive solution is injected into the pipe 54 from the small diameter pipe section 31 of the reducer 30. Also in this embodiment, since the small diameter pipe portion 31 extends to the lower side of the dissimilar joint 25, the corrosive solution does not come into contact with the dissimilar joint 25.

C. 4. Modifications The present invention is not limited to the above embodiments, and various modifications are possible. For example, as a method for forming the dissimilar material joint 25, in addition to the above-described joining method, it is also possible to use friction welding or the like in which two kinds of materials are brought into contact with each other and relatively rotated to frictionally heat. The forming method is arbitrary. Further, in the above embodiment, the material of the dissimilar material joint 25 is stainless steel and zirconium, but a combination of other materials such as stainless steel and titanium, or stainless steel and a titanium alloy (for example, titanium 5 tantalum) may be appropriately selected. it can.

Further, the present invention is not limited to the annular tank and the glove box as in the above embodiment, but can be applied to any apparatus using a pipe. For example, it can be applied to a container as shown in FIG. In the container shown in FIG. 6, a cylindrical nozzle 61 is welded and fixed to an upper wall portion of a rectangular or columnar container main body 60, and the dissimilar material joint 2 is fixed to the nozzle 61.
5 was fixed by welding. In this embodiment, also in this embodiment, the container body 60 and the nozzle 61 are made of stainless steel, and the tube 62 fixed to the reducer 30 by welding is made of zirconium.

FIG. 7 shows an example in which the tubes 70 and 71 are arranged obliquely. In this example, the small-diameter pipe portion 31 is made sufficiently long in order to reliably prevent liquid contact of the dissimilar material joint 25. FIG. 8 shows a modified example of the reducer 80. In this example, the upper end of the reducer 80 has the same diameter as the dissimilar material joint 25. In this example or the above-described embodiment, the reducer 80 (30)
It is also possible to make the small-diameter pipe portion 81 (31) closely contact the inner peripheral surface of the dissimilar joint 25. Further, the fluid flowing through the pipe is not limited to a radioactive solution, and the effect of the present invention can be obtained as long as the fluid has a corrosive solution.

[0027]

As described above, according to the present invention, the corrosion of the dissimilar material joint is reliably prevented, so that an effect that a pipe of any material can be connected and used is obtained.

[Brief description of the drawings]

FIG. 1 is a side sectional view showing an annular tank according to a first embodiment.

FIG. 2 is a plan view showing an annular tank according to the embodiment.

FIG. 3 is a side view showing a part of an annular tank to which an external pipe for high temperature is connected.

FIG. 4 is a side view showing a part of an annular tank to which a low-temperature external pipe is connected.

FIG. 5 is a side sectional view showing a glove box of a second embodiment.

FIG. 6 is a side sectional view showing an example in which the present invention is applied to a container.

FIG. 7 is a side sectional view showing an example in which tubes are arranged obliquely.

FIG. 8 is a side sectional view for explaining another example of the reducer.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Storage tank main body, 7 ... Upper ring (member), 22 ... Convex edge (member comprised of low corrosion resistance material), 25 ... Dissimilar material joint, 25a ... Lower end, 25b ... Upper end, 30 ... Reducer (Connecting pipe), 31 ... small diameter pipe (tube), 33 ...
External piping (pipe) for high temperature.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) F16L 58/18 F16L 13/02 G21D 1/00

Claims (3)

(57) [Claims] 1. A pipe made of a material having a high corrosion resistance through which a fluid flows therein and a member made of a material having a lower corrosion resistance than the pipe through which the fluid flows from the pipe. A connection structure for pipes, for welding and fixing a dissimilar joint formed of the same material as that of the above-mentioned member, and the other end of the above-mentioned member, which is made of the same material as the above-mentioned pipe,
At the other end of the dissimilar joint, one end of a connection pipe made of the same material as the other end is welded and fixed, and the pipe is welded and fixed to the other end of the connection pipe. Has one end portion and the other end portion having a pipe portion disposed on the inner peripheral side and the outer side of the dissimilar material joint, respectively, and an outer peripheral portion of the pipe portion is welded to an opening edge of the dissimilar material joint. ,
Moreover, the one end portion of the pipe portion has a length sufficient for an opening edge thereof to be located downstream of the dissimilar material joint. 2. The connecting pipe has a second pipe part extending radially outward from an outer periphery of the pipe part, and an edge of the second pipe part is welded to an opening edge of the dissimilar joint. 2. The pipe connection structure according to claim 1, wherein a gap is provided in the pipe between the pipe portion and the dissimilar material joint. 3. The pipe connection structure according to claim 1, wherein the material having high corrosion resistance is zirconium, and the material having low corrosion resistance is stainless steel.