JP2021181796A - Vacuum heat insulating pipe and maintenance method thereof - Google Patents

Abstract

To provide a vacuum heat insulating pipe excellent in work efficiency of maintenance work of maintaining vacuum performance, and capable of greatly reducing a maintenance cost.SOLUTION: A vacuum heat insulating pipe 1 is provided with a decompression space DS between an inner pipe 2 and an outer pipe 3, and has an exhaust hole 52 for evacuation that communicates with an exhaust port 34 for evacuation of the outer pipe 3. An evacuation body 5 in which the exhaust hole 52 for evacuation is closed by a closing part 53 is fixed to a peripheral wall 311 of the outer pipe 3, and the evacuation body 5 is detachably fixed by a brazing material 62 provided so as to be sealed along the outer peripheral edge of the evacuation body 5 on the outer pipe side.SELECTED DRAWING: Figure 4

Description

The present invention relates to a vacuum heat insulating pipe in which a decompression space is provided between the inner pipe and the outer pipe, and a maintenance method thereof.

Conventionally, when transporting a low-temperature fluid by a pipe, a vacuum heat insulating pipe in which a decompression space is provided by vacuuming between the inner pipe and the outer pipe has been used (see Patent Documents 1 to 3). As such a vacuum heat insulating pipe, as in Patent Document 1, an exhaust port is provided on the peripheral wall of the outer pipe, and vacuum is drawn from this exhaust port by a vacuum pump to create a decompression space between the inner pipe and the outer pipe. Is provided, or as in Patent Document 2, an exhaust port is provided in a joint in which an internal space communicating with the space between the inner pipe and the outer pipe is communicated, and a vacuum is drawn from the exhaust port of the joint to perform the joint. It is known that a decompression space is provided in the internal space of the above and the space between the inner pipe and the outer pipe communicating with the inner space. In the former case, a vacuum insulation pipe with a decompression space provided between the inner pipe and the outer pipe is transported to the pipe installation site in advance at the factory, and the vacuum insulation pipe does not need to be evacuated at the site. It is possible to install.

Jitsufuku No. 7-40791 Japanese Unexamined Patent Publication No. 2000-2440884 Japanese Unexamined Patent Publication No. 62-188894

By the way, in a vacuum insulation pipe in which a vacuum is drawn from the peripheral wall of the outer pipe to provide a decompression space between the inner pipe and the outer pipe, a leak from the closed part due to aged deterioration of the closed part of the exhaust port, an inner pipe and the outer pipe When a getter that adsorbs gas in the depressurized space is provided, the vacuum performance deteriorates with the passage of time due to the aged deterioration of the getter. Therefore, in order to maintain the required vacuum performance, maintenance is required to periodically replace the vacuum insulation pipe with a new vacuum insulation pipe.

However, the work of periodically replacing a large number of vacuum heat insulating pipes arranged in a predetermined transportation route is a very large-scale work, and the work efficiency of the maintenance work is inferior. Further, since the vacuum insulation pipe having a considerably long length and having a decompression space between the inner pipe and the outer pipe is expensive, the maintenance cost required for the work of periodically replacing the pipe is also high. Therefore, there is a demand for a vacuum insulation pipe that is excellent in maintenance work efficiency and can reduce maintenance cost.

The present invention has been proposed in view of the above problems, and an object of the present invention is to provide a vacuum heat insulating pipe and a maintenance method thereof, which are excellent in work efficiency of maintenance work for maintaining vacuum performance and can significantly reduce maintenance cost. And.

The vacuum heat insulating pipe of the present invention is a vacuum heat insulating pipe in which a decompression space is provided between the inner pipe and the outer pipe, and has an exhaust hole for vacuum drawing that communicates with the exhaust port of the outer pipe, and the vacuum pulling. A fixing material provided so that the evacuation body in which the evacuation hole is closed by the closing portion is fixed to the peripheral wall of the outer pipe and sealed along the outer peripheral edge of the evacuation body on the outer pipe side. The vacuum pulling body is detachably fixed.
According to this, it is possible to perform maintenance work simply by removing only the evacuation body or its peripheral members, cleaning the removed members, reattaching them after processing, or replacing them with new members, and then evacuation. , It is possible to improve the work efficiency of maintenance work that maintains vacuum performance. In addition, it is not necessary to remove the entire vacuum insulation pipe and replace it with a new vacuum insulation pipe, and it is only necessary to remove, reattach or replace some parts, which greatly reduces the maintenance cost for maintaining vacuum performance. can do. In addition, for example, even if the specifications of the vacuum insulation piping are changed over time and there is no vacuum insulation piping with the same specifications, maintenance can be performed without problems, and it is not affected by the environment such as the industry trend of vacuum insulation piping. In addition, maintenance work can be performed to maintain the vacuum performance continuously.

The vacuum insulation pipe of the present invention includes an exhaust passage that communicates with the exhaust port of the outer pipe, a getter accommodating portion that is provided above the exhaust passage so as to communicate with the exhaust passage and is open upward, and the getter accommodating portion. A getter house to be housed in a getter and a getter house having a communication hole communicating with the evacuation port of the outer tube and the evacuation hole for evacuation are fixed to the peripheral wall of the outer tube, and the evacuation body is evacuated. It is characterized in that the exhaust hole is arranged so as to communicate with the communication hole and close the opening above the getter accommodating portion, and is fixed to the upper surface of the getter accommodating portion with the fixing material.
According to this, the gas is adsorbed by the getter of the getter accommodating body, and the vacuum performance of the decompression space between the inner pipe and the outer pipe can be maintained for a long period of time. In addition, the detachably fixed vacuum pulling body can be removed, and the getter in the getter accommodating portion can be replaced with a new one, and maintenance can be performed to maintain a high degree of vacuum performance in the decompression space.

In the vacuum insulation pipe of the present invention, the getter accommodating portion and the communication hole are provided so as to surround the entire communication hole in a plan view, and the circumferential relief groove arranged on the inner peripheral side of the peripheral fixing material is described. It is characterized in that it is formed on the upper surface of the getter accommodating portion, on the lower surface of the vacuum pulling body, or on both the upper surface of the getter accommodating portion and the lower surface of the vacuum pulling body.
According to this, when the vacuum pulling body is fixed with the fixing material, the fixing material can be released to the peripheral relief groove so as not to enter the getter accommodating portion or the communication hole, and the fixing material can be released to the getter of the getter accommodating portion. Can be prevented from adhering to the getter and deteriorating the adsorption performance of the getter. Further, since it is possible to prevent the fixing material from entering the inside of the peripheral relief groove, it is possible to stably secure good removability in fixing with the removable fixing material.

The vacuum insulation pipe of the present invention is another fixing material provided so as to be sealed along the outer peripheral edge of the getter accommodating body on the outer pipe side, so that the getter accommodating body can be attached to and detached from the peripheral wall of the outer pipe. It is characterized by being fixed.
According to this, in addition to the vacuum pulling body, the getter housing body can be detachably fixed to ensure the removable property, so that the getter housing body can be cleaned to remove impurities. In addition, for example, in order to improve the vacuum performance and maintain the vacuum performance of the decompression space for a long time, the specifications of the vacuum performance are changed, such as increasing the number of getter housing parts of the getter housing and the number of getters housed in the getter housing. Can be easily adapted.

The vacuum heat insulating pipe of the present invention is characterized in that the inner pipe and the outer pipe are formed of a metal material, and the fixing material and the other fixing material are brazing materials.
According to this, the brazing material can be heated and the evacuation body and the getter accommodating body can be easily removed.

The maintenance method of the vacuum heat insulating pipe of the present invention is a maintenance method for maintaining the vacuum heat insulating pipe of the present invention, in which the fixing material is removed, the vacuum pulling body is removed from the upper surface of the getter accommodating body, and the closed portion is formed. The first step of removing the evacuation portion, the second step of exchanging the getter housed in the getter accommodating portion with a new getter, and the evacuation body from which the obstruction portion was removed are subjected to the evacuation hole for evacuation. Is placed on the upper surface of the getter accommodating portion so as to communicate with the communication hole and close the opening above the getter accommodating portion, and seal along the outer peripheral edge of the evacuation body on the outer tube side. The third step of providing a fixing material and fixing the vacuum pulling body to the upper surface of the getter accommodating body, and the first step of drawing a vacuum from the vacuum pulling exhaust hole and closing the vacuum pulling exhaust hole with a new closing portion. It is characterized by having four steps.
According to this, it is possible to perform maintenance for maintaining a high degree of vacuum performance in the vacuum space of the vacuum insulation pipe with very efficient and low cost work.

According to the present invention, it is possible to improve the work efficiency of the maintenance work for maintaining the vacuum performance of the vacuum heat insulating pipe, and it is possible to significantly reduce the maintenance cost.

The plan view of the vacuum insulation pipe of embodiment according to this invention. The vertical sectional view of the vacuum insulation pipe of an embodiment. An enlarged view of part A in FIG. An enlarged view of part B in FIG. A vertical section explanatory view showing a state in which the vacuum insulation pipes of the embodiment are connected. The flowchart which shows the maintenance process example of the vacuum insulation pipe of embodiment.

[Vacuum insulation piping of the embodiment]
As shown in FIGS. 1 to 5, the vacuum insulation pipe 1 of the embodiment according to the present invention is a vacuum insulation pipe 1 in which a decompression space DS is provided between the inner pipe 2 and the outer pipe 3. The inner tube 2 has a cylindrical shape such as a cylinder made of a metal material, and in the illustrated example, tapered portions 22 and 22 whose diameters gradually increase toward the outside are provided on the inner peripheral surfaces of both ends of the peripheral wall 21. It is formed so that the peripheral wall 21 gradually becomes thinner toward the tip at both ends. A female screw (not shown) is formed on the tapered portion 22. The length around the outer circumference of the inner pipe 2 is substantially constant over the entire length, and in the illustrated example, the inner pipe 2 is formed with the same outer diameter over the entire length. The inner pipe 2 is formed to be longer than the outer pipe 3, and both ends thereof are arranged so as to project from both ends of the outer pipe 3.

The outer pipe 3 has a substantially cylindrical shape such as a substantially cylindrical shape made of a metal material, and a length of the inner circumference is formed in the central portion of the outer pipe 3 to be larger than the length of the outer circumference of the inner pipe 2. Moreover, a cylindrical base 31 formed having substantially the same length over the entire length is provided. The base 31 of the outer tube 3 of the illustrated example is formed to have an inner diameter of the same diameter over the entire length and to be larger than the outer diameter of the inner tube 2. Both ends of the base 31 are provided with a tapered portion 32 that bends diagonally inward from the end of the base 31, and a sleeve portion 33 that bends and extends in the axial direction of the base 31 from the inner end of the tapered portion 32, respectively. ing. The sleeve portion 33 is formed so as to extend along the outer peripheral surface of the inner pipe 2, and in the illustrated example, the inner diameter of the sleeve portion 33 is formed to be the same as or slightly larger than the outer diameter of the inner pipe 2. The sleeve portions 33 and 33 at both ends are arranged inside the both ends where the tapered portions 22 and 22 of the inner pipe 2 are formed, and are fixed to the peripheral wall of the inner pipe 2 by welding or the like in a circumferential shape. The inner tube 2 and the outer tube 3 are sealed and fixed.

An exhaust port 34 for evacuation is formed in the central portion of the peripheral wall 311 of the base 31 of the outer pipe 3 in the axial direction, and an exhaust port 35 for getter adsorption exhaust is provided at a distance from the evacuation port 34 for evacuation. It is formed. The exhaust port 34 for evacuation and the exhaust port 35 for getter adsorption exhaust are arranged at substantially the same position in the circumferential direction of the peripheral wall 311 of the base 31. In the illustrated example, an exhaust port 35 for getter adsorption exhaust is arranged at one end side and the other end side of the exhaust port 34 for evacuation in the axial direction of the outer pipe 3, respectively. A plurality of getter suction / exhaust exhaust ports 35 are arranged side by side at intervals on each of the end side and the other end side.

A getter accommodating body 4 having a substantially rectangular parallelepiped shape is fixed to the peripheral wall 311 of the base 31 of the outer tube 3. The getter accommodating body 4 of the present embodiment is fixed with a brazing material 61 corresponding to another fixing material provided so as to be sealed along the outer peripheral edge of the base 41 of the getter accommodating body 4 on the outer tube 3 side. The getter accommodating body 4 is detachably fixed to the peripheral wall 311 of the outer tube 3 with a brazing material 61.

The getter accommodating body 4 has an exhaust port 34 for evacuation of the outer tube 3 and a communication hole 42 communicating with the evacuation hole 34 for evacuation described later. In the illustrated example, the outer tube 3 is formed on a substantially rectangular parallelepiped substrate 41. A communication hole 42 is provided so as to penetrate in the radial direction of the above. The getter accommodating body 4 has an exhaust passage 43 communicating with an exhaust port 35 for getter adsorption exhaust of the outer pipe 3, and in the illustrated example, the getter accommodating body 4 penetrates the substantially rectangular parallelepiped base 41 in the radial direction of the outer pipe 3. An exhaust passage 43 is provided.

A getter accommodating portion 44 is provided on the opposite side of the exhaust passage 43 of the getter accommodating body 4 from the outer pipe 3 side, that is, on the upper side of the exhaust passage 43 so as to communicate with the exhaust passage 43, and the getter accommodating portion 44 is on the outer pipe 3 side. It is open on the opposite side, that is, open upward. In the illustrated example, a plurality of getter accommodating portions 44 partitioned from each other are provided side by side in the axial direction of the outer pipe 3, and the getter 45 is accommodated in each getter accommodating portion 44.

On the side opposite to the outer tube 3 side of the getter accommodating body 4, a lid-shaped vacuum pulling body 5 having a substantially rectangular shape is arranged, and by being fixed to the getter accommodating body 4, the getter accommodating body 4 is fixed to the outside. It is detachably fixed to the peripheral wall 311 of the tube 3. The vacuum pulling body 5 of the present embodiment is fixed with a brazing material 62 corresponding to a fixing material provided so as to be sealed along the outer peripheral edge of the base 51 of the vacuum pulling body 5 on the outer tube 3 side, and is evacuated. The pulling body 5 is detachably fixed to the upper surface of the getter accommodating body 4 with a brazing material 62.

The evacuation body 5 has an evacuation hole 52 that communicates with the evacuation port 34 of the outer tube 3, and in the illustrated example, the evacuation body 5 extends in the radial direction of the outer tube 3 to a substantially rectangular parallelepiped substrate 51. An exhaust hole 52 for evacuation is provided. In the present embodiment, the evacuation body 5 is arranged so that the evacuation hole 52 communicates with the communication hole 42 of the getter accommodating body 4, and the evacuation hole 52 connects the communication hole 42 of the getter accommodating body 4. It is configured to communicate with the evacuation port 34 for evacuation of the outer pipe 3 through the outer pipe 3. The outer end of the evacuation hole 52 for evacuation is an enlarged diameter portion 521 that gradually expands in diameter toward the outside in order to facilitate evacuation by the vacuum pump. The closed portion 53 made of a glass material, a nickel material, or the like is fixed, and the evacuation hole 52 for evacuation is closed by the closed portion 53 in the enlarged diameter portion 521.

Further, the evacuation body 5 is arranged so as to close the opening above the getter accommodating portion 44, and is detachably fixed to the upper surface of the getter accommodating body 4 with a brazing material 62 in this state. The base 51 of the vacuum pulling body 5 of the illustrated example is formed to have a slightly smaller vertical and horizontal size in a plan view than the base 51 of the getter housing 4, and the vacuum pulling body 5 is formed of the base 41 of the getter housing 4. It is placed on the getter accommodating body 4 so that the upper surface or the outer surface is exposed in a circumferential shape.

The vacuum pulling body 5 is arranged so as to close the upper opening, and the space of the getter accommodating portion 44 in which the exhaust passage 43 is closed is formed so as to be slightly larger than the size of the accommodating getter 45 and not too large. NS. For example, when a substantially rectangular parallelepiped getter 45 is arranged in a substantially rectangular parallelepiped getter accommodating portion 44, between the upper surface of the getter 45 placed on the bottom surface of the getter accommodating portion 44 and the lower surface of the base 51 of the vacuum pulling body 5. When the separation distance is set to about 0.5 to 1.5 mm, the offset arrangement due to the movement of the getter 45 in the getter accommodating portion 44 is restricted, and the inner tube 2 and the outer tube 3 by the getter 45 are restricted. It is possible to reliably exert the expected gas adsorption performance for the space between them.

Circumferential relief grooves 46 and 54 are provided on the upper surface of the base 41 of the getter accommodating body 4 opposite to the outer tube 3 side and the lower surface of the vacuum pulling body 5 on the outer tube 3 side of the base 51. It is formed. The peripheral relief grooves 46 and 54 are provided so as to surround the getter accommodating portion 44 and the communication hole 42 in a plan view, respectively, and are arranged on the inner peripheral side of the brazing material 62 corresponding to the peripheral fixing material. When the vacuum pulling body 5 is fixed to the getter accommodating body 4 with the brazing material 62 by the peripheral relief grooves 46 and 54, the melted brazing material 62 is provided in the getter accommodating portion 44 and the communication hole 42. It is designed to prevent entry.

When the vacuum insulation pipes 1 of the present embodiment are connected and connected side by side in the axial direction, for example, as shown in FIG. 5, the female screw of the tapered portion 22 at one end of the inner pipe 2 of one of the vacuum insulation pipes 1 Male threads on both sides of the nipple 71, such as a hexagonal nipple, are screw-bonded to the female thread of the tapered portion 22 at the other end of the inner pipe 2 of the other vacuum insulation pipe 1, and heat is insulated so as to cover the entire screw connection portion. A material 72 is provided and connected (female screw and male screw are not shown). The heat insulating material 72 is provided in order to prevent deterioration of heat insulating property and prevention of dew condensation at the connecting portion when the low temperature fluid is transported by the connecting structure of the vacuum heat insulating pipe 1, and is preferably connected. To the base 31 of the outer pipe 3 of the vacuum heat insulating pipe 1 and the base 31 of the outer pipe 3 of the other vacuum heat insulating pipe 1, in other words, to the decompression space DS / DS of the vacuum heat insulating pipe 1.1 of one and the other. If it is provided so as to be continuously arranged and covered in the axial direction of the above, it is possible to further improve the heat insulating property at the connecting portion.

Next, a process example of the maintenance method of the vacuum insulation pipe 1 of the present embodiment will be described (see FIG. 6). First, the brazing material 62 of the fixing material to which the vacuum pulling body 5 of the vacuum heat insulating pipe 1 is fixed is melted and removed, the vacuum pulling body 5 is removed from the upper surface of the getter accommodating body 4, and the removed vacuum pulling body 5 is closed. The portion 53 is removed, and the enlarged diameter portion 521 of the evacuation hole 52 for evacuation is cleaned or reprocessed (S101). Further, the brazing material 61 of the fixing material fixing the getter housing 4 of the vacuum insulation pipe 1 is melted and removed, the getter housing 4 is removed from the peripheral wall 311 of the outer pipe 3, and the getter of the removed getter housing 4 is removed. The getter 45 is removed from the accommodating portion 44, the getter accommodating portion 44 is cleaned, and a new getter accommodating portion 44 is processed and formed as needed (S102).

After that, the getter accommodating body 4 is made to communicate the communication hole 42 with the exhaust port 34 for vacuuming of the peripheral wall 311 of the outer pipe 3 and the exhaust passage 43 with the exhaust port 35 for getter adsorption exhaust of the outer pipe 3. , A brazing material 61 as a fixing material is provided so as to be placed on the peripheral wall 311 of the outer tube 3 and sealed along the outer peripheral edge of the getter accommodating body 4 on the outer tube side, and the getter accommodating body 4 is placed on the peripheral wall of the outer tube 3. It is fixed to 311 and a new getter 45 is accommodated in the getter accommodating portion 44 and replaced (S103).

After that, the evacuation body 5 whose evacuation hole 52 was opened by removing the closing portion 53 was communicated with the evacuation hole 52 through the communication hole 42, and the getter accommodating portion 44 accommodating the new getter 45. The vacuum pulling body 5 is arranged on the upper surface of the getter accommodating body 4 so as to close the upper opening, and a brazing material 62 as a fixing material is provided so as to seal along the outer peripheral edge of the vacuum pulling body 5 on the outer tube 3 side. It is fixed to the upper surface of the getter housing 4 (S104).

Then, a vacuum pump is used to draw a vacuum from the vacuum drawing exhaust hole 52 of the vacuum drawing body 5, and the inner pipe 2 communicates with the vacuum drawing exhaust hole 52 and the communication hole 42, and the vacuum drawing exhaust port 34. After providing the decompression space DS in the space between the outer pipes 3, the enlarged diameter portion 521 of the evacuation hole 52 for evacuation is closed by the new closing portion 53, and the maintenance of the vacuum heat insulating pipe 1 is completed (S105).

According to the present embodiment, maintenance work can be performed simply by removing the evacuation body 5 and the getter accommodating body 4, cleaning and reattaching them after processing, or replacing them with new members as necessary, and then evacuation. This makes it possible to improve the work efficiency of maintenance work that maintains the vacuum performance of the vacuum insulation pipe 1. In addition, it is not necessary to remove the entire vacuum insulation pipe and replace it with a new vacuum insulation pipe, and since it is only necessary to remove, reattach or replace some parts, the maintenance cost for maintaining the vacuum performance is significantly increased. Can be reduced. In addition, for example, even if the specifications of the vacuum insulation pipe are changed with the passage of time and there is no vacuum insulation pipe with the same specifications, maintenance can be performed without any problem, and it depends on the environment such as the industry trend of the vacuum insulation pipe 1. Maintenance work that continuously maintains vacuum performance can be performed without this.

Further, the getter 45 of the getter accommodating body 4 can adsorb the gas, and the vacuum performance of the decompression space DS between the inner pipe 2 and the outer pipe 3 can be maintained for a long period of time. In addition, the detachably fixed vacuum pulling body 5 can be removed, and the getter 45 of the getter accommodating portion 44 can be replaced with a new one, and maintenance can be performed to maintain the high vacuum performance of the decompression space DS.

Further, when the vacuum pulling body 5 is fixed by the brazing material 62 by the peripheral relief grooves 46, 54, the peripheral relief groove 46, so that the melted brazing material 62 does not enter the getter accommodating portion 44 or the communication hole 42. It becomes possible to escape to 54, and it is possible to prevent the brazing material 62 from adhering to the getter 45 of the getter accommodating portion 44 and deteriorating the adsorption performance of the getter 45. Further, since the brazing material 62 can be prevented from entering the inside of the peripheral relief grooves 46 and 54, good removability in fixing with the removable brazing material 62 can be stably ensured.

Further, in addition to the vacuum pulling body 5, the getter housing body 4 can be detachably fixed to ensure the removable property, so that the getter housing body 4 can be cleaned to remove impurities. Further, for example, in order to improve the vacuum performance and maintain the vacuum performance of the decompression space DS for a long period of time, the number of getter accommodating portions 44 of the getter accommodating body 4 and the number of getters 45 accommodated therein may be increased. It can be easily adapted to specification changes.

Further, the inner pipe 2 and the outer pipe 3 are formed of a metal material, the fixing material for fixing the outer pipe 3 and the getter accommodating body 4 is a brazing material 61, and the fixing material for fixing the getter accommodating body 4 and the vacuum pulling body 5 is a brazing material. By using the material 62, the brazing materials 61 and 62 can be heated and the getter accommodating body 4 and the vacuum pulling body 5 can be easily removed.

[Scope of inclusion of the invention disclosed herein]
The invention disclosed in the present specification is, in addition to the inventions listed as inventions, embodiments and variations thereof, and to the extent applicable, these partial contents are changed to other contents disclosed in the present specification. Specified ones, or those specified by adding other contents disclosed in the present specification to these contents, or those partial contents are deleted to the extent that partial action and effect can be obtained, and are made into a higher concept. Includes what you have identified. The invention disclosed in the present specification also includes the following modifications and additional contents.

For example, in the vacuum heat insulating pipe 1 of the above embodiment, the upper surface of the getter accommodating body 4 opposite to the outer pipe 3 side of the base 41 and the lower surface of the vacuum pulling body 5 on the outer pipe 3 side of the base 51. Circumferential relief grooves 46 and 54 were formed on both sides of the getter, so that the melted brazing material 62 could be more reliably prevented from entering the getter accommodating portion 44 and the communication hole 42. A circumferential relief groove 46 formed on the upper surface of the surface opposite to the outer tube 3 side, and a peripheral relief groove 54 formed on the lower surface of the substrate 51 of the vacuum puller 5 on the outer tube 3 side surface. It is also good to form only one of them so that the melted brazing material 62 can be prevented from entering the getter accommodating portion 44 and the communication hole 42.

Further, in the maintenance process example of the vacuum heat insulating pipe 1 of the above embodiment, the getter accommodating body 4 is removed from the peripheral wall 311 of the outer pipe 3 for cleaning, and the getter accommodating body is placed on the peripheral wall 311 of the outer pipe 3 to be placed on the outer pipe 3. An example of a process of fixing the getter accommodating body 4 to the peripheral wall 311 by providing a brazing material 61 so as to be sealed along the outer peripheral edge on the side has been described, but only the evacuation body 5 is removed to connect the getter accommodating body 4 to the outer tube. The getter 45 housed in the getter housing 44 was removed and cleaned, and a new getter 45 was placed in the cleaned getter housing 44 to replace the getter 45 while keeping the state fixed to the peripheral wall 311 of 3. After that, it is also preferable to carry out the steps of S104 and S105.

Further, the vacuum heat insulating pipe 1 of the above embodiment has a configuration in which the getter accommodating body 4 and the getter 45 are installed, but the vacuum heat insulating pipe of the present invention is appropriate within the scope of the purpose of the present invention, for example, the present invention. The vacuum insulation pipe of the above has an evacuation hole for evacuation that communicates with the exhaust port of the outer pipe without installing the getter accommodating body 4 or the getter 45, and the evacuation hole for evacuation is closed by the closed portion. Also included is a vacuum insulated pipe in which the body is detachably fixed directly to the peripheral wall of the outer pipe. In this case, it is a fixing material provided so as to be sealed along the outer peripheral edge on the outer pipe side of the vacuum pulling body, and the vacuum pulling body is detachably fixed to the peripheral wall of the outer pipe.

Further, in the above embodiment, the parts related to the maintenance work, the evacuation port 34 for evacuation of the outer pipe 3 which is a member, the exhaust port 35 for suction exhaust, the getter accommodating body 4, and the evacuation body 5 are evacuated. By installing these parts and members in the substantially central part in the axial direction of 1 and arranging these parts and members at a position farther from the connecting part of the vacuum heat insulating pipe 1 which is inferior in heat insulating property to the vacuum heat insulating pipe 1, the vacuum heat insulating pipe 1 can be used. The vacuum insulation pipe of the present invention has a structure that suppresses temperature changes such as the connection structure of the vacuum insulation pipe during maintenance and the temperature rise of the transport fluid as much as possible. An exhaust port 34 for evacuation, an exhaust port 35 for suction exhaust, a getter accommodating body 4, and a vacuum drawing body 5 are installed at appropriate positions in the axial direction of the vacuum insulation pipe 1.

Further, the configuration of the inner pipe, the configuration of the outer pipe, the configuration of the connecting portion or the joint connecting the vacuum heat insulating pipes in the present invention are appropriate to the extent to which the present invention can be applied, and the configuration of the inner pipe 2 of the above embodiment , The configuration of the outer pipe 3 and the configuration of connecting the vacuum insulation pipe 1 are not limited.

The present invention can be used when transporting a low temperature fluid such as a low temperature gas by piping.

1 ... Vacuum insulation pipe 2 ... Inner pipe 21 ... Circumferential wall 22 ... Tapered part 3 ... Outer pipe 31 ... Base 311 ... Circumferential wall 32 ... Tapered part 33 ... Sleeve part 34 ... Exhaust port for evacuation 35 ... Getter suction Exhaust for exhaust Mouth 4 ... Getter accommodating body 41 ... Base 42 ... Communication hole 43 ... Exhaust passage 44 ... Getter accommodating part 45 ... Getter 46 ... Circumferential escape groove 5 ... Vacuum pulling body 51 ... Base 52 ... Vacuum pulling exhaust hole 521 ... Diameter expansion Part 53 ... Closure part 54 ... Circumferential escape groove 61, 62 ... Blow material 71 ... Nipple 72 ... Insulation material DS ... Insulation space

Claims (6)

A vacuum insulation pipe with a decompression space between the inner pipe and the outer pipe.
A vacuum pulling body having a vacuum pulling exhaust hole communicating with the exhaust port of the outer pipe and having the vacuum pulling exhaust hole closed at the closing portion is fixed to the peripheral wall of the outer pipe.
A vacuum insulation pipe characterized in that the vacuum pulling body is detachably fixed by a fixing material provided so as to be sealed along the outer peripheral edge of the vacuum pulling body on the outer pipe side. An exhaust passage that communicates with the exhaust port of the outer pipe, a getter accommodating portion that is provided above the exhaust passage so as to communicate with the exhaust passage and is open upward, a getter that is accommodated in the getter accommodating portion, and the above. A getter accommodating body having an exhaust port of the outer pipe and a communication hole communicating with the evacuation hole for evacuation is fixed to the peripheral wall of the outer pipe.
The evacuation body is arranged so as to communicate the evacuation hole for evacuation with the communication hole and close the opening above the getter accommodating portion, and is fixed to the upper surface of the getter accommodating portion with the fixing material. The vacuum insulation pipe according to claim 1. A circumferential relief groove provided so as to surround the entire getter accommodating portion and the communication hole in a plan view and arranged on the inner peripheral side of the circumferential fixing material is provided on the upper surface of the getter accommodating portion or on the upper surface of the getter accommodating portion. The vacuum insulation pipe according to claim 2, wherein the vacuum insulating pipe is formed on the lower surface of the vacuum pulling body, or on both the upper surface of the getter accommodating portion and the lower surface of the vacuum pulling body. Another fixing material provided so as to be sealed along the outer peripheral edge of the getter accommodating body on the outer tube side, characterized in that the getter accommodating body is detachably fixed to the peripheral wall of the outer tube. The vacuum insulation pipe according to claim 2 or 3. The vacuum insulation pipe according to claim 4, wherein the inner pipe and the outer pipe are formed of a metal material, and the fixing material and the other fixing material are brazing materials. The maintenance method for vacuum insulation piping according to any one of claims 2 to 5.
The first step of removing the fixing material, removing the vacuum pulling body from the upper surface of the getter accommodating body, and removing the closed portion.
The second step of exchanging the getter housed in the getter housing part with a new getter, and
The evacuation body from which the obstruction has been removed is arranged on the upper surface of the getter accommodating portion so as to communicate the evacuation hole for evacuation with the communication hole and close the opening above the getter accommodating portion. A third step of providing a fixing material so as to seal along the outer peripheral edge of the evacuation body on the outer tube side and fixing the evacuation body to the upper surface of the getter accommodating body.
A method for maintaining a vacuum heat-insulated pipe, comprising a fourth step of drawing a vacuum from the exhaust hole for evacuation and closing the exhaust hole for evacuation with a new closed portion.

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