Double-wall pipe airtightness detection equipment for LNG (Liquefied Natural Gas) ship

Abstract

The invention provides double-wall pipe airtightness detection equipment for an LNG (Liquefied Natural Gas) ship. The double-wall pipe airtightness detection equipment comprises a base, a double-wall pipe supporting assembly, a sealing plug, a tension assembly and a detection assembly, the double-wall pipe supporting assembly is arranged on the base, and the double-wall pipe supporting assembly is of a telescopic structure and used for supporting the arc-shaped side wall of the double-wall pipe. The sealing plugs are used for blocking the two ends of the double-wall pipe, and the tension assembly is used for tensioning the sealing plugs at the two ends of the double-wall pipe so that the sealing plugs can tightly press the ends of the double-wall pipe. The detection assembly is arranged on the sealing plug. According to the double-wall pipe airtightness detection equipment for the LNG ship, through the innovative design that the pulling force assembly pulls the sealing plug tightly to press the end of the double-wall pipe, the problem that the sealing effect of the two ends of the double-wall pipe is poor in the prior art is fundamentally solved. The double-wall pipe airtightness detection device is matched with the telescopic double-wall pipe supporting assembly to provide stable supporting so as to adapt to different pipe diameters, and the detection assembly is integrated on the sealing plug, so that efficient, reliable and accurate airtightness detection of the double-wall pipe (especially the key connection area of the end portion of the double-wall pipe) is achieved.

Description

Technical Field

[0001] This invention relates to the field of airtightness testing equipment, and more specifically, to an airtightness testing device for double-walled pipes used in LNG ships. Background Technology

[0002] Double-walled pipes for LNG ships are primarily used for transporting natural gas in LNG dual-fuel powered vessels. Different double-walled pipe products are employed depending on the specific operating conditions. For LNG fuel supply pipelines within the engine room, double-walled piping is designed according to ship classification standards. The double-walled pipe employs an inner and outer pipe structure. The inner pipe transports natural gas, while the outer pipe serves as a second layer of protection and monitors for leaks in the inner pipe, enhancing the safety of gas delivery. For LNG refueling pipelines, vacuum double-walled pipes are preferred. These pipes consist of an inner pipe, an outer pipe, a cryogenic absorbent, and multiple layers of insulation material. The inner and outer layers are evacuated to a high vacuum to improve the pipeline's thermal insulation capacity, reduce LNG transport cooling loss, decrease BOG emissions, and enhance fuel supply safety.

[0003] When connecting two double-walled pipes, flanges and bolts are typically used to splice and fix them together. After the two flanges are installed, the most likely place for leakage is at the flange structure. Therefore, an airtightness test is required before leaving the factory. The existing testing method involves sealing both ends of the double-walled pipe and conducting a pressure test. If the pressure change inside the pipe is less than a set value within a certain period of time, it can be determined that there is no leakage. However, the existing testing equipment has poor sealing effect at both ends of the double-walled pipe. Summary of the Invention

[0004] In view of this, the present invention proposes a double-walled pipe airtightness testing device for LNG ships to solve the problems existing in the prior art.

[0005] To achieve the above objectives, the present invention proposes a double-walled pipe airtightness testing device for LNG ships, comprising a base, a double-walled pipe support assembly, a sealing plug, a tension assembly, and a testing assembly; The double-walled tube support assembly is mounted on the base. The double-walled tube support assembly is a telescopic structure used to support the arc-shaped sidewalls of the double-walled tube. The sealing plug is used to seal both ends of the double-walled tube, and the tensioning assembly is used to tighten the sealing plugs at both ends of the double-walled tube so that the sealing plugs press against the ends of the double-walled tube. The detection component is mounted on the sealing plug.

[0006] In one embodiment, the sealing plug includes a plug holder, a main plug body, and an annular plug body; The main plug is located in the center of one side of the plug holder. The main plug is a cylindrical structure used to seal the inner tube. The annular plug and the main plug are located on the same side of the plug holder, with the annular plug located outside the main plug. The annular plug and the main plug are coaxially arranged to seal the annular gap between the outer tube and the inner tube.

[0007] In one embodiment, the outer arcuate surface of the main plug has a plurality of first sealing protrusions, and each of the first sealing protrusions is spaced apart along the central axis of the main plug. The outer and inner arc-shaped surfaces of the annular plug have multiple second sealing protrusions, and each second sealing protrusion is spaced apart along the central axis of the annular plug. The stopper has a limiting structure on one side near the main stopper and the annular stopper for contacting the end face of the outer tube.

[0008] In one embodiment, the main plug body has a connecting ring on the side opposite to the plug holder, one end of the tension assembly is connected to the connecting ring located at one end of the double-walled tube via a first rope, and the other end of the tension assembly is connected to the connecting ring located at the other end of the double-walled tube via a second rope, and the tension assembly tightens the two sealing plugs by tightening the first rope or the second rope.

[0009] In one embodiment, the tension assembly includes a housing, a hook, a second chain, a fourth sprocket, a third sprocket, and a power mechanism; Both the fourth sprocket and the third sprocket are rotatably connected to the outer casing, and the fourth sprocket and the third sprocket are arranged along the central axis of the double-walled tube; The second chain is sleeved on the fourth sprocket and the third sprocket, and the second chain is used to connect with the second rope. The hook is fixedly disposed on the end of the housing away from the second rope, and the hook is used to connect with the first rope. The power mechanism is mounted on the housing and is used to drive the third sprocket to rotate.

[0010] In one embodiment, the power mechanism includes a motor, a first sprocket, a second sprocket, and a first chain; The motor is fixedly mounted on the housing, and the first sprocket is fixedly mounted on the output shaft of the motor; The second sprocket is coaxially fixed with the third sprocket and can rotate relative to the housing. The first chain is sleeved on the first sprocket and the second sprocket.

[0011] In one embodiment, the diameter of the second sprocket is greater than the diameter of the first sprocket, the diameter of the second sprocket is greater than the diameter of the third sprocket, and the diameter of the fourth sprocket is greater than the diameter of the third sprocket.

[0012] In one embodiment, the detection component includes a first air guide tube, a first pressure gauge, a first valve, a second air guide tube, a second valve, and a second pressure gauge; The first air guide tube passes through the main plug body, and the first pressure gauge and the first valve are connected to the side of the first air guide tube near the plug. The second air guide tube passes through the annular plug, and the second valve and the second pressure gauge are connected to the side of the second air guide tube near the plug.

[0013] In one embodiment, the double-walled tube support assembly includes at least two sets of first cylinders and support seats, each set of first cylinders and support seats being arranged along the central axis of the double-walled tube; The first cylinder is vertically arranged, the fixed end of the first cylinder is fixedly connected to the base, and the movable end of the first cylinder is fixedly connected to the bottom of the support seat. The support seat is a semi-annular structure used to support the arc-shaped surface of the double-walled tube.

[0014] In one embodiment, the LNG ship double-wall pipe airtightness detection equipment further includes a leak detection component, which includes two transparent sealing shells. The bottom of one of the sealing shells is fixedly mounted on the base. The sealing shell is located below the double-wall pipe and is connected to a connector for connection to a water supply system. Another sealing housing is mounted on the base via a telescopic bracket, and the sealing housing is positioned above the double-walled tube; When the two sealing shells are in complete contact with the outer wall of the double-walled pipe, they form a sealing cavity surrounding the outside of the double-walled pipe flange connection structure. When the sealing cavity is filled with water, it is used to observe the leakage point at the double-walled pipe flange connection structure. The sealing housing has a semi-annular structure, and a sealing ring is provided at the part of the sealing housing that contacts the double-walled tube.

[0015] Compared with existing technologies, the beneficial effects of the LNG ship double-wall pipe airtightness testing equipment of the present invention are as follows: The innovative design of the tension component tightening the sealing plug to press the double-wall pipe end fundamentally solves the problem of poor sealing effect at both ends of the double-wall pipe in existing technologies. Combined with a retractable double-wall pipe support component providing stable support to adapt to different pipe diameters, and a testing component integrated on the sealing plug, efficient, reliable, and accurate airtightness testing of the double-wall pipe (especially its critical end connection area) is achieved. This equipment effectively ensures the sealing quality of the double-wall pipe ends at the factory, reduces the risk of leakage at the flange connection of the LNG ship fuel system, and ultimately significantly improves the safety of LNG fuel transportation. Attached Figure Description

[0016] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. In the drawings: Figure 1 This is a schematic diagram of the structure of the double-walled pipe airtightness testing equipment for LNG ships in an embodiment of the present invention; Figure 2 For the present invention Figure 1 Enlarged view of a portion of point A in the middle; Figure 3 This is a schematic diagram of the tensile component in an embodiment of the present invention; Figure 4 This is a schematic diagram of the structure of the sealing shell in an embodiment of the present invention; Figure 5 For the present invention Figure 4 The sectional view in the image.

[0017] Reference numerals: 11. Base; 12. First cylinder; 13. Support seat; 14. Pad; 15. Vertical plate; 16. Top plate; 17. Second cylinder; 2. Double-walled tube; 21. Outer tube; 22. Inner tube; 3. Sealing plug; 31. Plug support; 32. Limiting structure; 33. Main plug body; 34. Annular plug body; 35. First sealing protrusion; 36. Second sealing protrusion; 37. Connecting ring; 41. First air guide tube; 42. 43. First pressure gauge; 44. First valve; 45. Second air guide pipe; 46. Second valve; 47. Second pressure gauge; 58. Housing; 59. Motor; 50. First sprocket; 51. Second sprocket; 52. First chain; 53. Second chain; 54. Fourth sprocket; 55. Third sprocket; 66. Hook; 77. First rope; 68. Second rope; 79. Sealing housing; 70. Connector; 71. Sealing ring. Detailed Implementation

[0018] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the disclosure to those skilled in the art. It should be noted that, unless otherwise specified, the embodiments and features described herein can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0019] Reference Figure 1This embodiment proposes an airtightness testing device for double-walled pipes used in LNG ships, including a base 11, a double-walled pipe support assembly, a sealing plug 3, a tensioning assembly, and a testing assembly. The sealing plug 3 is used to seal both ends of the double-walled pipe 2, and the tensioning assembly is used to tighten the sealing plugs 3 at both ends of the double-walled pipe 2, so that the sealing plugs 3 press against the ends of the double-walled pipe 2.

[0020] In the above embodiment, sealing plugs 3 are inserted into both ends of the double-walled tube 2 for physical sealing, and a pulling force is applied using a tensioning component to pull the sealing plugs 3 at both ends towards the middle. This axial tension allows the sealing plugs 3 to be pressed evenly and firmly onto the end sealing surfaces of the double-walled tube 2. This active tightening sealing method, compared to simply sealing or pressing, generates a more reliable and durable end-face sealing force, greatly reducing misjudgments (pressure holding failures) caused by poor end sealing during testing, and ensuring the accuracy and reliability of the test results.

[0021] The double-walled pipe support assembly is mounted on the base 11. This telescopic structure supports the arc-shaped sidewalls of the double-walled pipe 2. The arc-shaped support surface of the assembly conforms to the pipe wall, providing stable radial support, preventing pipe deformation or displacement, and ensuring that the axial clamping force of the sealing plug 3 effectively acts on the end face. Its telescopic nature allows it to adapt to double-walled pipes of different diameters, improving the equipment's applicability and working efficiency.

[0022] The detection components are mounted on the sealing plug 3. Pressure sensors, leak detector interfaces, or related detection elements are integrated inside or at the end of the sealing plug, allowing connection to a detection system (such as inflation lines, pressure gauges, or leak detectors) simultaneously with sealing. This integrated design avoids additional complex connecting lines and interfaces, simplifies operation, reduces potential leak points, and improves detection efficiency and convenience.

[0023] The LNG ship double-walled pipe airtightness testing equipment of this embodiment fundamentally solves the problem of poor sealing effect at both ends of double-walled pipes in the prior art by using an innovative tension component to tighten the sealing plug 3 and press it against the end of the double-walled pipe 2. Combined with a retractable double-walled pipe support component to provide stable support to adapt to different pipe diameters, and a testing component integrated on the sealing plug 3, it achieves efficient, reliable, and accurate airtightness testing of the double-walled pipe 2 (especially its critical end connection area). This equipment can effectively ensure the sealing quality of the double-walled pipe ends at the factory, reduce the risk of leakage at the flange connection of the LNG ship fuel system, and ultimately significantly improve the safety of LNG fuel transportation.

[0024] The double-walled tube 2 includes an outer tube 21 and an inner tube 22. During testing, the inner tube 22 is tested first. Sealing plugs 3 are used to seal both ends of the double-walled tube 2, and a tensioning assembly is used to tighten the two sealing plugs 3 to ensure a tight seal. The inner tube 22 is then pressurized using a testing assembly. After a certain pressure holding time, if the airtightness test is passed, the outer tube 21 is then tested, following the same procedure as the inner tube 22. If the airtightness test fails, the tube is reworked.

[0025] In some embodiments, reference Figure 2 The sealing plug 3 includes a plug holder 31, a main plug body 33, and an annular plug body 34. The main plug body 33 is located in the center of one side of the plug holder 31. The main plug body 33 has a cylindrical structure and is used to seal the inner tube 22. The annular plug body 34 and the main plug body 33 are located on the same side of the plug holder 31. The annular plug body 34 is located outside the main plug body 33. The annular plug body 34 is coaxially arranged with the main plug body 33 and is used to seal the annular gap between the outer tube 21 and the inner tube 22.

[0026] The main plug 33 is centrally located and can be precisely inserted into and seal the port of the inner tube 22. The annular plug 34 is coaxially wrapped around the outside of the main plug 33, and its shape and size are designed for precise insertion into and sealing of the annular gap between the outer tube 21 and the inner tube 22. The plug holder 31 serves as a common mounting base, ensuring that the relative positions of the main plug 33 and the annular plug 34 are fixed and coaxial, perfectly fitting the end structure of the double-walled tube.

[0027] This coaxial nested design of "one core and one ring" fundamentally solves the problem of having two independent channels (the inner tube channel and the annular gap) at the end of a double-walled pipe that require sealing. It can physically seal these two channels in one go, ensuring that the medium will not leak from either channel during airtightness testing. This significantly improves the accuracy and efficiency of the seal and avoids the installation complexity and seal mismatch problems caused by using multiple independent seals.

[0028] The plug 31 acts as a "force distributor," ensuring that the applied axial tensile force is applied synchronously and evenly to the main plug 33 and the annular plug 34, allowing both to press with sufficient pressure against their respective sealing surfaces (the inner tube end face and the annular gap end face). This guarantees that both critical sealing points receive reliable sealing force, preventing localized sealing failure due to uneven force distribution.

[0029] The main plug 33 and the annular plug 34 are precisely positioned on the plug holder 31, and their outer contours (the cylindrical outer surface and the inner and outer surfaces of the annular plug) are designed to match the shape of the inner tube hole and the annular gap at the end of the double-walled tube. This allows the main plug 33 to fit tightly against the inner wall of the end of the inner tube 22, and the annular plug 34 to simultaneously fit against the inner wall of the outer tube 21 and the outer wall of the inner tube 22 (i.e., the two side walls of the annular gap), forming an effective sealing line or sealing surface. The plug holder 31, as a relatively large and stable platform, provides space and convenience for the installation of testing components (such as connectors and sensor interfaces). More importantly, this separate sealing structure allows for the design of independent testing channels: the inner tube cavity can be pressurized separately to test the inner tube's sealing performance.

[0030] In some embodiments, reference Figure 2 The outer arc-shaped surface of the main plug body 33 has multiple first sealing protrusions 35, and each first sealing protrusion 35 is spaced apart along the central axis of the main plug body 33; the outer and inner arc-shaped surfaces of the annular plug body 34 both have multiple second sealing protrusions 36, and each second sealing protrusion 36 is spaced apart along the central axis of the annular plug body 34; the plug holder 31 has a limiting structure 32 on one side near the main plug body 33 and the annular plug body 34 for abutting against the end face of the outer tube 21.

[0031] Each protrusion forms an independent annular sealing line. Even if a single seal fails slightly due to surface defects or low-temperature shrinkage, subsequent protrusions can still provide redundant sealing protection. The protruding structure is more deformable than a flat surface, allowing it to better conform to the inner wall of the inner tube 22 (main plug body) and the inner and outer walls of the annular gap (annular plug body), especially accommodating minor ovality or scratches at the tube end. The limiting structure 32 ensures that the sealing protrusion is compressed to the optimal working deformation range designed, fully filling the gap to provide sealing force while preventing failure due to excessive deformation. The limiting surface ensures that the plug 31 is parallel and fitted to the end face of the outer tube 21, keeping the main plug body 33 and the annular plug body 34 coaxial with the axis of the double-walled tube, avoiding localized sealing failure caused by off-center loading.

[0032] In some embodiments, the main plug body 33 has a connecting ring 37 on the side opposite to the plug 31. One end of the tension assembly is connected to the connecting ring 37 located at one end of the double-walled tube 2 via a first rope 61, and the other end of the tension assembly is connected to the connecting ring 37 located at the other end of the double-walled tube 2 via a second rope 62. The tension assembly tightens the two sealing plugs 3 by tightening the first rope 61 or the second rope 62.

[0033] The flexible rope automatically adjusts its angle during tightening, ensuring the tension direction remains along the axis of the double-walled pipe (even with minor installation deviations in the sealing plugs at both ends). This guarantees that the main plug body 33 and the annular plug body 34 of the sealing plug 3 are evenly pressed against the sealing surface, preventing localized seal failure due to misalignment. Compared to rigid tie rods, the rope can buffer instantaneous tensile impacts, protecting the sealing protrusions from shear damage and extending the life of the seal. The sealing plug 3 can be independently installed at both ends of the double-walled pipe before being connected to the tensioning assembly via the rope, enabling step-by-step operation and improving the assembly efficiency of large pipe sections. The tensioning assembly can be wirelessly controlled via remote control, preventing wiring connections from affecting the sealing performance of the sealing plug 3.

[0034] In some embodiments, reference Figure 3 The tension assembly includes a housing 51, a hook 59, a second chain 56, a fourth sprocket 57, a third sprocket 58, and a power mechanism. Both the fourth sprocket 57 and the third sprocket 58 are rotatably connected to the housing 51 and are arranged along the central axis of the double-walled tube 2. The second chain 56 is sleeved on the fourth sprocket 57 and the third sprocket 58 and is used to connect to the second rope 62. The hook 59 is fixedly disposed at the end of the housing 51 away from the second rope 62 and is used to connect to the first rope 61. The power mechanism is disposed on the housing 51 and is used to drive the third sprocket 58 to rotate.

[0035] In the above embodiments, the linear motion trajectory of the second chain 56 ensures that the tension is transmitted strictly along the pipe axis, eliminating lateral force components. The coaxial layout of the double sprockets ensures that the tightening direction of the second rope 62 is always parallel to the pipe, forcing the two sealing plugs 3 to move in opposite directions along the axis, ensuring that the sealing protrusions of the main plug body 33 and the annular plug body 34 uniformly press against the pipe end, avoiding off-center leakage.

[0036] A power mechanism (such as a motor and reducer) drives the third sprocket 58 to rotate, which in turn pulls the second rope 62 via the second chain 56, creating a reverse tension at the fixed end of the hook 59. The torque amplification effect of the sprocket system allows the low-power power mechanism to output several tons of axial tension, fully compressing the sealing protrusion to its designed deformation. During the airtightness pressure test (which typically lasts for several hours), a constant clamping force on the sealing plug 3 can be maintained without continuous energy consumption, preventing seal failure due to force relaxation.

[0037] In some embodiments, the power mechanism includes a motor 52, a first sprocket 53, a second sprocket 54, and a first chain 55; the motor 52 is fixedly mounted on the housing 51, and the first sprocket 53 is fixedly mounted on the output shaft of the motor 52; the second sprocket 54 and the third sprocket 58 are coaxially fixedly mounted and can rotate relative to the housing 51, and the first chain 55 is sleeved on the first sprocket 53 and the second sprocket 54.

[0038] In some embodiments, the diameter of the second sprocket 54 is larger than the diameter of the first sprocket 53, the diameter of the second sprocket 54 is larger than the diameter of the third sprocket 58, and the diameter of the fourth sprocket 57 is larger than the diameter of the third sprocket 58. The superposition of the two-stage chain drive enables the low-power motor to output several tons of axial tensile force, fully compressing the sealing protrusion.

[0039] In some embodiments, the detection assembly includes a first air guide tube 41, a first pressure gauge 42, a first valve 43, a second air guide tube 44, a second valve 45, and a second pressure gauge 46; the first air guide tube 41 passes through the main plug body 33, and the first pressure gauge 42 and the first valve 43 are connected to the side of the first air guide tube 41 near the plug 31; the second air guide tube 44 passes through the annular plug body 34, and the second valve 45 and the second pressure gauge 46 are connected to the side of the second air guide tube 44 near the plug 31.

[0040] During the pressure holding test, both the inner and outer pipes are tested separately. If the pressure drops on the first pressure gauge 42, the inner pipe 22 is considered to be leaking. If the pressure drops on the second pressure gauge 46, the annular gap is considered to be leaking. Valves control the intake and exhaust of air. Pressure gauges facilitate observation of changes in the pipe pressure.

[0041] In some embodiments, the double-walled pipe support assembly includes at least two sets of first cylinders 12 and support seats 13, each set of first cylinders 12 and support seats 13 being arranged along the central axis of the double-walled pipe 2; the first cylinders 12 are vertically arranged, with the fixed end of the first cylinder 12 fixedly connected to the base 11, and the movable end of the first cylinder 12 fixedly connected to the bottom of the support seat 13, the support seat 13 being a semi-annular structure used to support the arcuate surface of the double-walled pipe 2. The semi-annular structure covers the pipe body's arc surface of ≥150°, dispersing the pipe's self-weight and avoiding line contact stress concentration caused by traditional V-blocks. The arrangement of the first cylinders 12 allows the double-walled pipe to move up and down, facilitating loading and unloading.

[0042] In some embodiments, reference Figure 4 and Figure 5 The LNG ship double-walled pipe airtightness testing equipment also includes a leak observation component, which comprises two transparent sealing housings 71. One sealing housing 71 is fixedly mounted on the base 11 at its bottom and is positioned below the double-walled pipe 2. This sealing housing 71 is connected to a connector 72 for connection to the water supply system. The other sealing housing 71 is mounted on the base 11 via a telescopic bracket and is positioned above the double-walled pipe 2. When the two sealing housings 71 are completely in contact with the outer wall of the double-walled pipe 2, they form a sealed cavity surrounding the flange connection structure of the double-walled pipe 2. When the sealed cavity is filled with water, it is used to observe leaks at the flange connection structure of the double-walled pipe 2. The sealing housing 71 has a semi-annular shell structure, and a sealing ring 73 is provided at the part of the sealing housing 71 that contacts the double-walled pipe 2.

[0043] The upper and lower semi-annular sealing shells 71 enclose the flange, and the sealing ring 73 presses against the pipe wall to form a closed water chamber. After water is injected through the joint 72 to purge air, the flange area is completely submerged. Leakage at the flange face / bolt holes is ≥0.1mm. 3 The gas generates a visible chain of bubbles. The operator can directly mark the coordinates of the leak point on the surface of the transparent sealing housing 71. The upper housing is vertically raised and lowered via a telescopic bracket, while the lower housing is fixed to the base 11. Water seal observation can be initiated simultaneously during the pressure holding phase of the airtightness test.

[0044] In the above embodiment, the sealing housing 71 located below the double-walled tube 2 is fixedly connected to the base 11 via a pad 14. The telescopic bracket includes a vertical plate 15, a top plate 16, and a second cylinder 17; the bottom of the vertical plate 15 is fixedly connected to the base 11, the top of the vertical plate 15 is fixedly connected to the top plate 16, the top plate 16 and the vertical plate 15 are arranged at a right angle, the bottom of the top plate 16 is fixedly connected to the fixed end of the second cylinder 17, the second cylinder 17 is arranged vertically, and the movable end of the second cylinder 17 is fixedly connected to the sealing housing 71 located above the double-walled tube 2.

[0045] During leak detection, firstly, the first cylinder 12 is shortened, causing the double-walled pipe to descend and land on the lower sealing housing 71, ensuring a tight fit between the sealing housing 71 and the double-walled pipe. Then, the second cylinder 17 is extended, causing the upper sealing housing 71 to descend until it presses against the double-walled pipe, with the end faces of the two sealing housings 71 pressing against each other. The sealing ring 73 is compressed, preventing leakage. Finally, water from the water supply system is used to fill the cavity formed by the two sealing housings 71 through the connector 72. The location of the leak is then determined by observing whether steam buildup occurs in the flange connection structure (the double-walled pipe is in a pressurized state).

[0046] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A double-walled pipe airtightness testing device for LNG ships, characterized in that, Includes a base (11), a double-walled tube support assembly, a sealing plug (3), a tension assembly, and a detection assembly; The double-walled tube support assembly is disposed on the base (11). The double-walled tube support assembly is a telescopic structure used to support the arc-shaped sidewall of the double-walled tube (2). The sealing plug (3) is used to seal both ends of the double-walled tube (2), and the tensioning assembly is used to tighten the sealing plug (3) at both ends of the double-walled tube (2) so that the sealing plug (3) presses against the end of the double-walled tube (2); The detection component is mounted on the sealing plug (3).

2. The LNG ship double-walled pipe airtightness testing equipment according to claim 1, characterized in that, The sealing plug (3) includes a plug holder (31), a main plug body (33), and an annular plug body (34). The main plug (33) is located in the center of one side of the plug (31). The main plug (33) is a cylindrical structure used to seal the inner tube (22). The annular plug (34) and the main plug (33) are located on the same side of the plug (31), the annular plug (34) is located outside the main plug (33), and the annular plug (34) is coaxially arranged with the main plug (33) to seal the annular gap between the outer tube (21) and the inner tube (22).

3. The LNG ship double-walled pipe airtightness testing equipment according to claim 2, characterized in that, The outer arc-shaped surface of the main plug (33) has a plurality of first sealing protrusions (35), and each of the first sealing protrusions (35) is spaced apart along the central axis of the main plug (33). The annular plug (34) has multiple second sealing protrusions (36) on both its outer and inner arc-shaped surfaces, and each second sealing protrusion (36) is spaced apart along the central axis of the annular plug (34). The plug (31) has a limiting structure (32) on one side near the main plug (33) and the annular plug (34) for contacting the end face of the outer tube (21).

4. The LNG ship double-walled pipe airtightness testing equipment according to claim 2, characterized in that, The main plug body (33) has a connecting ring (37) on the side opposite to the plug holder (31). One end of the tension assembly is connected to the connecting ring (37) at one end of the double-walled tube (2) via a first rope (61), and the other end of the tension assembly is connected to the connecting ring (37) at the other end of the double-walled tube (2) via a second rope (62). The tension assembly tightens the two sealing plugs (3) by tightening the first rope (61) or the second rope (62).

5. The LNG ship double-wall pipe airtightness testing equipment according to claim 4, characterized in that, The tension assembly includes a housing (51), a hook (59), a second chain (56), a fourth sprocket (57), a third sprocket (58), and a power mechanism; The fourth sprocket (57) and the third sprocket (58) are both rotatably connected to the outer casing (51), and the fourth sprocket (57) and the third sprocket (58) are arranged along the central axis of the double-walled tube (2); The second chain (56) is sleeved on the fourth sprocket (57) and the third sprocket (58). The second chain (56) is used to connect with the second rope (62). The hook (59) is fixedly disposed at one end of the outer shell (51) away from the second rope (62). The hook (59) is used to connect with the first rope (61). The power mechanism is mounted on the housing (51) and is used to drive the third sprocket (58) to rotate.

6. The LNG ship double-walled pipe airtightness testing equipment according to claim 5, characterized in that, The power mechanism includes a motor (52), a first sprocket (53), a second sprocket (54), and a first chain (55); The motor (52) is fixedly mounted on the housing (51), and the first sprocket (53) is fixedly mounted on the output shaft of the motor (52); The second sprocket (54) is coaxially fixed with the third sprocket (58) and can rotate relative to the outer shell (51). The first chain (55) is sleeved on the first sprocket (53) and the second sprocket (54).

7. The LNG ship double-walled pipe airtightness testing equipment according to claim 6, characterized in that, The diameter of the second sprocket (54) is greater than the diameter of the first sprocket (53), the diameter of the second sprocket (54) is greater than the diameter of the third sprocket (58), and the diameter of the fourth sprocket (57) is greater than the diameter of the third sprocket (58).

8. The LNG ship double-wall pipe airtightness testing equipment according to claim 2, characterized in that, The detection assembly includes a first air guide tube (41), a first pressure gauge (42), a first valve (43), a second air guide tube (44), a second valve (45), and a second pressure gauge (46). The first air guide tube (41) passes through the main plug body (33), and the first air guide tube (41) is connected to the first pressure gauge (42) and the first valve (43) on the side near the plug (31). The second air guide tube (44) passes through the annular plug (34), and the second valve (45) and the second pressure gauge (46) are connected to the side of the second air guide tube (44) near the plug (31).

9. The LNG ship double-walled pipe airtightness testing equipment according to claim 2, characterized in that, The double-walled tube support assembly includes at least two sets of first cylinders (12) and support seats (13), and each set of first cylinders (12) and support seats (13) is arranged along the central axis of the double-walled tube (2); The first cylinder (12) is set vertically. The fixed end of the first cylinder (12) is fixedly connected to the base (11). The movable end of the first cylinder (12) is fixedly connected to the bottom of the support seat (13). The support seat (13) is a semi-ring structure used to support the arc-shaped surface of the double-walled tube (2).

10. The LNG ship double-walled pipe airtightness testing equipment according to claim 9, characterized in that, The LNG ship double-wall pipe air tightness detection equipment also includes a leak observation component, which includes two transparent sealing shells (71). The bottom of one of the sealing shells (71) is fixedly set on the base (11). The sealing shell (71) is set below the double-wall pipe (2). The sealing shell (71) is connected to a connector (72) for connection to the water supply system. Another sealing housing (71) is mounted on the base (11) via a telescopic bracket, and the sealing housing (71) is positioned above the double-walled tube (2); When the two sealing shells (71) are in complete contact with the outer wall of the double-walled pipe (2), they form a sealing cavity surrounding the outside of the flange connection structure of the double-walled pipe (2). When the sealing cavity is filled with water, it is used to observe the leakage point at the flange connection structure of the double-walled pipe (2). The sealing housing (71) is a semi-annular housing structure, and a sealing ring (73) is provided at the part of the sealing housing (71) that is in contact with the double-walled tube (2).

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