Vacuum sealing assembly, vacuum double-wall pipe and vacuum construction process thereof

Abstract

The present application belongs to the technical field of vacuum double-wall pipe, and particularly relates to a vacuum sealing assembly, a vacuum double-wall pipe and a vacuum construction process thereof. The vacuum sealing assembly comprises a vacuum valve seat, a vacuum valve core is arranged in the vacuum valve seat, the lower end of the vacuum valve seat is open, communication ports are arranged on both sides of the vacuum valve seat, and vacuum sealing rings are arranged between the upper and lower sections of the vacuum valve seat and the vacuum valve core. The vacuum double-wall pipe comprises a plurality of vacuum double-wall pipe sections, each of which comprises an inner pipe, an outer pipe with closed two ends is arranged on the outer pipe, a mounting pipe with one-side sealing is arranged on the outer pipe, the vacuum valve seat is arranged between the mounting pipe and the outer pipe, and the space between the mounting pipe and the outer pipe is communicated with the communication ports; the inner pipes of adjacent two vacuum double-wall pipe sections are connected, a connecting pipe is arranged between the mounting pipes of adjacent two vacuum double-wall pipe sections, and a vacuum obtaining port is arranged on the connecting pipe. The present application provides a vacuum sealing assembly, a vacuum double-wall pipe and a vacuum construction process for improving the vacuum degree of a vacuum sandwich.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of vacuum double-wall pipe, in particular to a vacuum sealing assembly, a vacuum double-wall pipe and a vacuum construction process thereof. BACKGROUND

[0002] LNG is a clean and green energy, and more and more ships begin to use LNG as fuel under the background of energy saving and emission reduction. The filling of LNG fuel ship fuel inevitably needs to use corresponding pipelines as conveying carriers. At present, the conveying pipelines are mostly bare pipes and vacuum double-wall pipes, wherein the vacuum double-wall pipes are basically made on site and vacuumized, and the vacuum degree is difficult to reach an ideal state, and it is difficult to reach a long-term vacuum life. The above two conveying modes cannot well reduce the heat loss of LNG in the conveying process. Correspondingly, if the vacuum double-wall pipe can reach an ideal vacuum degree and vacuum life, the heat loss of LNG will be solved, and the gasification loss in the fuel filling process will also be minimized.

[0003] The traditional vacuum double-wall pipe is mostly made on site and vacuumized or preformed in a factory, and the pipe sections are spliced on site. In the splicing process, the vacuum interlayer is easily filled with air and water, which causes the target vacuum degree to be unable to be reached in the subsequent on-site vacuum treatment, and the vacuum life cannot be guaranteed. At present, the similar vacuum products on the market are mostly vacuumized on site, and limited by the on-site equipment and construction conditions, the vacuum degree of the vacuum double-wall pipe is difficult to reach an ideal state (mostly 0.5-5 Pa). SUMMARY

[0004] In order to solve the above problems existing in the prior art, the purpose of the present application is to provide a vacuum sealing assembly for improving the vacuum degree of a vacuum interlayer, a vacuum double-wall pipe and a vacuum construction process thereof.

[0005] The technical scheme adopted by the present application is as follows:

[0006] A vacuum sealing assembly comprises a vacuum valve seat, a vacuum valve core is arranged in the vacuum valve seat, the lower end of the vacuum valve seat is open, communication ports are arranged on both sides of the vacuum valve seat, and vacuum sealing rings are arranged between the upper and lower segments of the vacuum valve seat and the vacuum valve core.

[0007] The upper and lower segments of the vacuum valve seat are provided with vacuum sealing rings between the vacuum valve core, so that when the vacuum valve core is pressed down, the vacuum sealing ring of the lower segment of the vacuum valve core moves to the lower side of the communication port, and at this time, the vacuum valve seat is sealed on both sides of the communication port. When the vacuum valve core is lifted, the vacuum sealing ring of the lower segment of the vacuum valve core moves to the upper side of the communication port, and at this time, the lower end opening of the vacuum valve seat is communicated with the communication port. The vacuum sealing assembly of the present application can realize two sealing states, and when applied to a vacuum double-wall pipe, the vacuum degree of the vacuum interlayer of the vacuum double-wall pipe section can be ensured to be always not lost.

[0008] In a preferred embodiment of the present invention, a vacuum protective cover is fastened to the vacuum valve seat, and the vacuum protective cover is connected to the vacuum valve core. The vacuum protective cover protects the vacuum valve seat and the vacuum valve core, preventing impurities from entering. The vacuum valve seat supports the vacuum protective cover, and the vacuum protective cover supports the vacuum valve core, preventing the vacuum valve core from being sucked to the lower part of the vacuum valve seat and ensuring the accurate positioning of the vacuum valve core.

[0009] A vacuum double-walled tube includes several vacuum double-walled tube sections. Each vacuum double-walled tube section includes an inner tube, an outer tube sealed at both ends is fitted over the inner tube, and a mounting tube with a single-sided seal is fitted over the outer tube. The vacuum valve seat of the vacuum sealing assembly is installed between the mounting tube and the outer tube, and the space between the mounting tube and the outer tube is connected to a connecting port. The inner tubes of two adjacent vacuum double-walled tube sections are connected, and a connecting tube is connected between the mounting tubes of two adjacent vacuum double-walled tube sections. A vacuum acquisition port is provided on the connecting tube.

[0010] The vacuum double-walled tube section of this invention is prefabricated in the factory. The vacuum interlayer between the inner and outer tubes is evacuated, and the vacuum valve core of the vacuum sealing assembly is in the depressed position. The space between the installation tube and the outer tube is isolated from the vacuum interlayer, preventing vacuum loss. During on-site construction, the sealed space between the two vacuum double-walled tube sections is first evacuated through the vacuum inlet. Then, the vacuum valve core of the vacuum sealing assembly is raised, connecting the sealed space between the two vacuum double-walled tube sections to the two vacuum interlayers. During construction, the vacuum interlayer remains airtight, preventing vacuum loss. On-site, only the sealed space between the two vacuum double-walled tube sections needs to be evacuated, reducing the difficulty of on-site vacuuming and further ensuring the vacuum level of the vacuum double-walled tube.

[0011] This invention, by installing a vacuum sealing component on the vacuum-sealed pipe section, reduces the impact of factory-prefabricated vacuum double-walled pipe sections on the vacuum level to zero during on-site construction. This invention ensures that after the entire vacuum double-walled pipe pipeline is constructed, the vacuum level reaches or is very close to the factory prefabrication level (approximately 5 × 10⁻⁶). -2 Pa).

[0012] As a preferred embodiment of the present invention, the vacuum acquisition port is connected to a vacuum acquisition component.

[0013] In a preferred embodiment of the present invention, the vacuum acquisition component includes a vacuum acquisition valve seat connected to the vacuum acquisition port, a vacuum acquisition valve core disposed within the vacuum acquisition valve seat, and a vacuum acquisition sealing ring disposed between the vacuum acquisition valve core and the vacuum acquisition valve seat. During vacuuming, the valve stem of the vacuuming device is connected to the vacuum acquisition valve core, and the valve stem pulls up the vacuum acquisition valve core, allowing the vacuuming device to perform vacuuming. After vacuuming is completed, the valve stem presses the vacuum acquisition valve core back into the vacuum acquisition valve seat, preventing vacuum loss.

[0014] As a preferred embodiment of the present invention, a vacuum acquisition protective cover is sleeved on the vacuum acquisition valve seat. The vacuum acquisition protective cover can protect the vacuum acquisition valve seat and the vacuum acquisition valve core, preventing impurities from entering. Moreover, when the vacuum double-walled tube leaks, the high-pressure effect can cause the vacuum acquisition valve core to break out, and the vacuum acquisition protective cover can block the vacuum acquisition valve core to ensure safety. The vacuum acquisition protective cover is threadedly connected to the vacuum acquisition valve seat, and a plurality of small holes are provided on the vacuum acquisition protective cover.

[0015] As a preferred embodiment of the present invention, a flared mouth is provided inside the upper end of the vacuum acquisition valve seat, and a limiting ring cooperating with the flared mouth is provided at the upper end of the vacuum acquisition valve core. The flared mouth can block the limiting ring to prevent the vacuum acquisition valve core from being sucked into the connecting pipe under the action of vacuum negative pressure.

[0016] As a preferred embodiment of the present invention, an expansion joint is provided on the inner tube. The expansion joints are installed in a determined direction, and one expansion joint is connected to each section of the vacuum double-walled tube section.

[0017] As a preferred embodiment of the present invention, a support plate is connected between the inner tube and the outer tube, and a communication hole is provided on the support plate. The support plate can support the outer tube and increase the strength of the outer tube.

[0018] A vacuum construction process for a vacuum double-walled tube includes the following steps:

[0019] Butt-weld the inner tubes of two adjacent sections of the vacuum double-armed tube sections;

[0020] Weld a connecting pipe between the installation pipes of two adjacent sections of the vacuum double-walled tubes;

[0021] Use the vacuum acquisition port to evacuate the closed space between the two vacuum double-walled tube sections, and a vacuum degree ≤ 5×10 -2 Pa is considered qualified;

[0022] Lift the vacuum valve cores of the vacuum sealing components on both sides of the connecting pipe upward once. After lifting, the vacuum interlayer between the inner tube and the outer tube and the space between the outer tube and the installation pipe are connected.

[0023] The beneficial effects of the present invention are:

[0024] The vacuum double-walled tube section of this invention is prefabricated in the factory. The vacuum interlayer between the inner and outer tubes is evacuated, and the vacuum valve core of the vacuum sealing assembly is in the depressed position. The space between the installation tube and the outer tube is isolated from the vacuum interlayer, preventing vacuum loss. During on-site construction, the sealed space between the two vacuum double-walled tube sections is first evacuated through the vacuum inlet. Then, the vacuum valve core of the vacuum sealing assembly is raised, connecting the sealed space between the two vacuum double-walled tube sections to the two vacuum interlayers. During construction, the vacuum interlayer remains airtight, preventing vacuum loss. On-site, only the sealed space between the two vacuum double-walled tube sections needs to be evacuated, reducing the difficulty of on-site vacuuming and further ensuring the vacuum level of the vacuum double-walled tube. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the structure of a vacuum double-walled tube;

[0026] Figure 2 yes Figure 1 A magnified view of a section at point A in the middle;

[0027] Figure 3 This is a cross-sectional view of a vacuum double-walled tube;

[0028] Figure 4 yes Figure 3 A magnified view of a section at point B in the middle;

[0029] Figure 5 This is a partial structural diagram of a vacuum double-walled tube;

[0030] Figure 6 Cross-sectional view of the vacuum sealing assembly;

[0031] Figure 7 This is a cross-sectional view of the vacuum acquisition component.

[0032] In the diagram: 1-Vacuum sealing assembly; 2-Vacuum double-walled pipe section; 3-Connecting pipe; 4-Vacuum acquisition assembly; 11-Vacuum valve seat; 12-Vacuum valve core; 13-Connecting port; 14-Vacuum sealing ring; 15-Vacuum protective cover; 21-Inner pipe; 22-Outer pipe; 23-Mounting pipe; 24-Single-sided; 25-Pre-welded pipe; 26-Expansion joint; 27-Support plate; 31-Vacuum acquisition port; 41-Vacuum acquisition valve seat; 42-Vacuum acquisition valve core; 43-Vacuum acquisition sealing ring; 44-Vacuum acquisition protective cover; 111-Retaining ring; 411-Bell mouth; 421-Limiting ring. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0034] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention. It should be noted that, unless otherwise specified, the embodiments and features described in the embodiments of the invention can be combined with each other.

[0035] like Figure 5 As shown, the vacuum sealing assembly 1 of this embodiment includes a vacuum valve seat 11, a vacuum valve core 12 disposed inside the vacuum valve seat 11, an opening at the lower end of the vacuum valve seat 11, and connecting ports 13 on both sides of the vacuum valve seat 11. Vacuum sealing rings 14 are disposed between the upper and lower sections of the vacuum valve seat 11 and the vacuum valve core 12. A vacuum protective cover 15 is connected to the upper end of the vacuum valve seat 11. The protective cover serves a specific function.

[0036] A vacuum protective cover 15 is fastened to the vacuum valve seat 11, and the vacuum protective cover 15 is threadedly connected to the vacuum valve core 12. The vacuum protective cover 15 protects the vacuum valve seat 11 and the vacuum valve core 12, preventing impurities from entering. The vacuum valve seat 11 supports the vacuum protective cover 15, and the vacuum protective cover 15 supports the vacuum valve core 12, preventing the vacuum valve core 12 from being sucked to the lower part of the vacuum valve seat 11 and ensuring the accurate positioning of the vacuum valve core 12.

[0037] Two vacuum sealing rings 14 are provided between the upper and lower sections of the vacuum valve seat 11 and the vacuum valve core 12. When the vacuum valve core 12 is in the raised position, the vacuum valve core 12 and the four vacuum sealing rings 14 are all located on the upper side of the connecting port 13. When the vacuum valve core 12 is in the depressed position, the two vacuum sealing rings 14 of the lower section of the vacuum valve core 12 are located on the lower side of the connecting port 13, and the two vacuum sealing rings 14 of the upper section of the vacuum valve core 12 are located on the upper side of the connecting port 13. A retaining ring 111 is provided at the lower opening of the vacuum valve seat 11. The retaining ring 111 can block the vacuum valve core 12 and prevent the vacuum valve core 12 from coming out of the vacuum valve seat 11.

[0038] In this invention, vacuum sealing rings 14 are provided between the upper and lower sections of the vacuum valve seat 11 and the vacuum valve core 12. When the vacuum valve core 12 is pressed down, the vacuum sealing ring 14 of the lower section of the vacuum valve core 12 moves to the lower side of the connecting port 13, at which point the vacuum valve seat 11 is sealed on both sides of the connecting port 13. When the vacuum valve core 12 is raised, the vacuum sealing ring 14 of the lower section of the vacuum valve core 12 moves to the upper side of the connecting port 13, at which point the lower opening of the vacuum valve seat 11 connects with the connecting port 13. The vacuum sealing assembly 1 of this invention can achieve two sealing states. When applied to a vacuum double-walled tube, it can ensure that the vacuum level of the vacuum interlayer of the vacuum double-walled tube section 2 is never lost.

[0039] like Figures 1-6 As shown, the vacuum double-walled tube of this embodiment includes several vacuum double-walled tube sections 2. A vacuum sealing assembly 1 is installed on each vacuum double-walled tube section 2. Each vacuum double-walled tube section includes an inner tube 21, with an outer tube 22 (sealed at both ends) surrounding the inner tube 21. The space between the inner tube 21 and the outer tube 22 is a vacuum interlayer. A single-sided sealed mounting tube 23 is fitted onto the outer tube 22. The vacuum valve seat 11 of the vacuum sealing assembly 1 is installed between the mounting tube 23 and the outer tube 22. The space between the mounting tube 23 and the outer tube 22 is connected to a connecting port 13. The inner tubes 21 of two adjacent vacuum double-walled tube sections 2 are connected, and a connecting tube 3 connects the mounting tubes 23 of two adjacent vacuum double-walled tube sections. A vacuum acquisition port 31 is provided on the connecting tube 3. The connecting tube 3 is a Haver tube.

[0040] The vacuum double-walled tube section of this invention is prefabricated in the factory. The vacuum interlayer between the inner tube 21 and the outer tube 22 is evacuated, and the vacuum valve core 12 of the vacuum sealing assembly 1 is in the depressed position. The space between the mounting tube 23 and the outer tube 22 is isolated from the vacuum interlayer, preventing vacuum loss. During on-site construction, the sealed space between the two vacuum double-walled tube sections 2 is first evacuated through the vacuum inlet 31, and then the vacuum valve core 12 of the vacuum sealing assembly 1 is raised, connecting the sealed space between the two vacuum double-walled tube sections 2 with the two vacuum interlayers. During construction, the vacuum interlayer never allows air to enter, avoiding vacuum loss. On-site, only the sealed space between the two vacuum double-walled tube sections 2 needs to be evacuated, reducing the difficulty of on-site vacuuming and further ensuring the vacuum level of the vacuum double-walled tube.

[0041] This invention, by installing a vacuum sealing component 1 on the vacuum-sealed pipe section, reduces the impact of factory-prefabricated vacuum double-walled pipe sections on the vacuum level to zero during on-site construction. This invention ensures that after the entire vacuum double-walled pipe pipeline is constructed, the vacuum level reaches or is very close to the factory prefabrication level (approximately 5 × 10⁻⁶). -2 Pa).

[0042] It should be noted that both ends of the outer tube 22 of the vacuum double-wall tube section 2 are provided with mounting tubes 23, so that a connecting tube 3 is connected between every two adjacent vacuum double-arm tube sections, so that the sealed space between every two adjacent vacuum double-wall tube sections 2 can be evacuated.

[0043] A single-sided surface 24 is provided between the end of the outer tube 22 and the inner tube 21. The single-sided surface 24 is used to seal the vacuum interlayer between the inner tube 21 and the outer tube 22 to prevent vacuum loss in the vacuum interlayer.

[0044] A pre-welded pipe 25 is connected between the end of the mounting pipe 23 furthest from the connecting pipe 3 and the outer pipe 22. The pre-welded pipe 25 is used to connect the mounting pipe 23 and to seal the space between the end of the pre-welded pipe 25 furthest from the connecting pipe 3 and the outer pipe 22.

[0045] To facilitate evacuation of the space between the two vacuum double-walled pipe sections 2, a vacuum acquisition assembly 4 is connected to the vacuum acquisition port 31. The vacuum acquisition assembly 4 includes a vacuum acquisition valve seat 41 connected to the vacuum acquisition port 31, a vacuum acquisition valve core 42 disposed within the vacuum acquisition valve seat 41, and a vacuum acquisition sealing ring 43 disposed between the vacuum acquisition valve core 42 and the vacuum acquisition valve seat 41. During evacuation, the valve rod of the evacuation device is threadedly connected to the vacuum acquisition valve core 42, and the valve rod pulls up the vacuum acquisition valve core 42, initiating evacuation. After evacuation is completed, the valve rod presses the vacuum acquisition valve core 42 back into the vacuum acquisition valve seat 41 to prevent vacuum loss.

[0046] A vacuum acquisition protective cover 44 is fitted onto the vacuum acquisition valve seat 41. The vacuum acquisition protective cover 44 protects the vacuum acquisition valve seat 41 and the vacuum acquisition valve core 42, preventing impurities from entering. Furthermore, when a leak occurs in the vacuum double-walled tube, the high pressure can cause the vacuum acquisition valve core 42 to be ejected; the vacuum acquisition protective cover 44 can prevent this, ensuring safety. The vacuum acquisition protective cover 44 is threadedly connected to the vacuum acquisition valve seat 41, and several small holes are provided on the vacuum acquisition protective cover 44.

[0047] The upper inner side of the vacuum valve seat 41 is provided with a flared opening 411, and the upper end of the vacuum valve core 42 is provided with a limiting ring 421 that cooperates with the flared opening 411. The flared opening 411 can block the limiting ring 421, preventing the vacuum valve core 42 from being sucked into the connecting pipe 3 under the action of vacuum negative pressure.

[0048] An expansion joint 26 is provided on the inner tube 21. The expansion joint 26 is installed in a defined direction, and one expansion joint 26 is connected to each section of the vacuum double-walled tube 2.

[0049] A support plate 27 is connected between the inner tube 21 and the outer tube 22, and the support plate 27 is provided with a connecting hole. The support plate 27 can support the outer tube 22 and increase the strength of the outer tube 22.

[0050] The vacuum construction process for the vacuum double-walled tube in this embodiment includes the following steps:

[0051] S1: Butt weld the inner tubes 21 of the two adjacent vacuum double-arm tube sections;

[0052] S2: Weld a connecting pipe 3 between the mounting pipes 23 of two adjacent vacuum double-walled pipes; wherein, the connecting pipe 3 can be a Haver pipe;

[0053] S3: Weld vacuum-obtaining component 4 onto connecting pipe 3;

[0054] S4: Using the vacuum obtaining component 4 from step S3, evacuate the sealed space between the two vacuum double-walled tube sections 2, with a vacuum degree ≤ 5 × 10⁻⁶. -2 Pa is considered qualified; during vacuuming, the valve stem of the vacuuming device is threadedly connected to the vacuum obtaining valve core 42, the valve stem pulls up the vacuum obtaining valve core 42, and the vacuuming device performs vacuuming; after vacuuming is completed, the valve stem presses the vacuum obtaining valve core 42 into the vacuum obtaining valve seat 41 to avoid vacuum loss.

[0055] S5: The vacuum valve core 12 of the vacuum sealing assembly 1 on both sides of the connecting pipe 3 is lifted upwards once. After lifting, the vacuum interlayer between the inner pipe 21 and the outer pipe 22, and the space between the outer pipe 22 and the mounting pipe 23 will be... Figure 5 The channels indicated by the middle arrow are connected;

[0056] S6: Repeat steps S1 to S5 above to connect the entire project pipeline in sequence.

[0057] In this invention, the unique structure of the vacuum sealing component 1, coupled with the corresponding construction process, ensures that the vacuum double-walled pipe can achieve zero vacuum loss during on-site construction, highlighting the unique advantages of factory-prefabricated high-vacuum double-walled pipes.

[0058] This invention is not limited to the above-described optional embodiments. Anyone can derive other various forms of products under the guidance of this invention. However, regardless of any changes made in their shape or structure, any technical solution that falls within the scope of the claims of this invention shall be protected by this invention.

Claims

1. A vacuum double-walled tube, characterized in that: The system includes a vacuum sealing assembly, which includes a vacuum valve seat (11), a vacuum valve core (12) inside the vacuum valve seat (11), an opening at the lower end of the vacuum valve seat (11), and connecting ports (13) on both sides of the vacuum valve seat (11). Vacuum sealing rings (14) are provided between the upper and lower sections of the vacuum valve seat (11) and the vacuum valve core (12). A vacuum protective cover (15) is fastened to the vacuum valve seat (11), and the vacuum protective cover (15) is connected to the vacuum valve core (12). It also includes several vacuum double-walled pipe sections (2). The vacuum double-walled pipe section includes an inner pipe (21), and an outer pipe (22) with both ends closed is fitted over the inner pipe (21). A single-sided sealed mounting pipe (23) is fitted over the outer pipe (22). The vacuum valve seat (11) of the vacuum sealing assembly (1) is installed between the mounting pipe (23) and the outer pipe (22). The space between the mounting pipe (23) and the outer pipe (22) is connected to the connecting port (13). The inner pipes (21) of two adjacent vacuum double-walled pipe sections (2) are connected. A connecting pipe (3) is connected between the mounting pipes (23) of two adjacent vacuum double-walled pipe sections. A vacuum acquisition port (31) is provided on the connecting pipe (3). The vacuum acquisition port (31) is connected to a vacuum acquisition component (4); The vacuum acquisition component (4) includes a vacuum acquisition valve seat (41) connected to the vacuum acquisition port (31), a vacuum acquisition valve core (42) is provided inside the vacuum acquisition valve seat (41), and a vacuum acquisition sealing ring (43) is provided between the vacuum acquisition valve core (42) and the vacuum acquisition valve seat (41). A vacuum obtaining protective cover (44) is fitted onto the vacuum obtaining valve seat (41). The upper end of the vacuum valve seat (41) is provided with a flared mouth (411), and the upper end of the vacuum valve core (42) is provided with a limiting ring (421) that cooperates with the flared mouth (411).

2. A vacuum double-walled tube according to claim 1, characterized in that: An expansion joint (26) is provided on the inner tube (21).

3. A vacuum double-walled tube according to claim 1, characterized in that: A support plate (27) is connected between the inner tube (21) and the outer tube (22), and a connecting hole is provided on the support plate (27).

4. A vacuum construction process for a vacuum double-walled tube, using the vacuum double-walled tube according to any one of claims 1 to 3, characterized in that: Includes the following steps: The inner tubes (21) of two adjacent vacuum double-arm tube sections are butt welded together; Weld a connecting pipe (3) between the mounting pipes (23) of two adjacent vacuum double-walled tubes; The vacuum acquisition port (31) is used to evacuate the sealed space between the two vacuum double-wall pipe sections (2), and a vacuum degree ≤ 5×10 - 2 Pa is regarded as qualified; The vacuum valve core (12) of the vacuum sealing assembly (1) on both sides of the connecting pipe (3) is lifted upwards once. After the lifting, the vacuum interlayer between the inner pipe (21) and the outer pipe (22) and the space between the outer pipe (22) and the mounting pipe (23) are connected.

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