Self-limiting multi-directional flexible compensation structure for double-wall pipe and application

Abstract

This invention provides a self-limiting multi-directional flexible compensation structure for double-walled pipes and its application. The self-limiting multi-directional flexible compensation structure for double-walled pipes includes: an inner pipe assembly, including a connected inner corrugated pipe and an inner intermediate pipe, with a displacement baffle on the outer wall of the inner intermediate pipe; and an outer pipe assembly, coaxially sleeved outside the inner pipe assembly, including a connected outer corrugated pipe and an outer intermediate pipe, with a limiting ring plate of thickness δ on the inner wall of the outer intermediate pipe; there are two displacement baffles located on both sides of the limiting ring plate, with a distance L between the two displacement baffles, where L = δ + 2X and X is 10–30 mm. This invention can effectively solve the problems of thermal expansion stress release and vibration absorption in double-walled pipes with limited space and dimensions, meeting the safety operation requirements of double-walled pipe systems in dual-fuel powered ships and the transportation of cryogenic media such as liquid hydrogen, liquid oxygen, and LNG.

Description

Technical Field

[0001] This invention relates to the field of expansion joint technology, and more specifically, to a self-limiting multi-directional flexible compensation structure for double-walled tubes and its application. Background Technology

[0002] With the implementation of the IMO Tier III emission regulations, liquefied natural gas (LNG) has become the most mature transitional fuel in the shipping industry due to its advantages such as cleanliness, low carbon emissions, and economy. Therefore, newly built container ships and LNG carriers generally adopt LNG dual-fuel power systems. As the key to connecting the gas supply valve group and the dual-fuel engine, the double-walled pipeline is usually composed of an inner and outer pipe coaxially mounted, and its safe operation is of paramount importance.

[0003] Because the inner pipe is used to transport high-pressure, low-temperature media (such as LNG with a pressure of up to 30 MPa and a temperature of -163°C), and the annular gap between the inner and outer pipes is usually connected to the atmosphere or filled with inert gases such as nitrogen to achieve ventilation, explosion protection and cold insulation functions; because the space in the ship's engine room is limited and it always operates under low-frequency vibration and temperature fluctuation conditions, the double-walled pipeline will generate huge axial and radial stresses; if they are not effectively released, they can easily lead to pipeline deformation, weld cracking or fatigue failure, which in turn can cause gas leakage.

[0004] To address this, Chinese Patent CN108266289A provides a high-pressure gas double-walled pipe, including an inner pipe and an outer pipe. An outer pipe elbow is provided at intervals on the outer pipe as a compensating element. An elastic support is provided in the annular space between the outer pipe and the inner pipe, which can absorb stress, vibration, and release thermal expansion displacement, and has a long service life. However, since the addition of elbows will increase the friction resistance of the internal medium, it will inevitably cause pipeline impact vibration, which is not conducive to the long-term safe operation of the pipeline.

[0005] Chinese patent CN218625962U discloses a double-walled expansion joint for combustible gas pipelines, including an inner protective pipe and an outer protective pipe sleeved outside the inner protective pipe; the inner protective pipe is provided with an inner corrugated pipe, and the outer protective pipe is provided with an outer corrugated pipe; a double-walled pipe flange is provided at each end of the inner and outer protective pipes, and an airtight annular space is formed between the inner and outer protective pipes; ventilation holes are provided on the double-walled pipe flanges to discharge leaked gas in the airtight annular space. This solution can absorb vibration and some thermal expansion displacement, but it does not consider the effect of thermal expansion stress of the outer pipe; because the inner pipe is in deep cryogenic contraction under actual working conditions, while the outer pipe is at ambient temperature or elongated due to heating, the deformation of the inner and outer corrugated pipes is uneven, which can easily cause stress concentration or even excessive deformation of one side of the corrugated pipe, leading to failure.

[0006] Chinese patent CN106813036A discloses a gas fuel pipeline compensator with a double-wall structure, including flanges, a protective cover, an outer bellows, and an inner bellows. The inner bellows and two flanges form the inner cavity of the compensator for gas fuel, while the inner and outer bellows and the two flanges form the outer cavity of the compensator for air. Each flange has evenly distributed waist holes along its circumference, and these waist holes communicate with the outer cavity of the compensator. One end of the protective cover is fixed to one flange, while the other end is free and rests on the other flange. As an integrated double-wall bellows, this design not only has extremely stringent requirements for installation coaxiality, but also suffers from excessively high stress in some parts of the pipeline due to the consistent deformation trend and amount of the two bellows, affecting operational safety. Summary of the Invention

[0007] The problem solved by this invention is how to solve the uneven deformation of the inner and outer corrugated pipes caused by the thermal expansion and contraction stress of the double-walled pipe.

[0008] To address the above problems, this invention provides a self-limiting multi-directional flexible compensation structure for double-walled tubes, comprising:

[0009] The inner tube assembly includes a connected inner corrugated tube and an inner intermediate tube, wherein a displacement baffle is provided on the outer wall of the inner intermediate tube;

[0010] The outer tube assembly is coaxially sleeved on the outside of the inner tube assembly, including a connected outer corrugated tube and an outer intermediate tube. The inner wall of the outer intermediate tube is provided with a limiting ring plate with a thickness of δ.

[0011] There are two displacement baffles located on both sides of the limiting ring plate. The distance between the two displacement baffles is L, where L = δ + 2X and X is 10 to 30 mm.

[0012] Preferably, the displacement baffle is welded and fixed to the outer wall of the inner intermediate tube and is annular, the single-sided distance between the displacement baffle and the outer intermediate tube is 10-20mm, the limiting ring plate is welded and fixed to the inner wall of the outer intermediate tube, the single-sided distance between the limiting ring plate and the inner intermediate tube is 5-30mm, and the single-sided distance between the inner intermediate tube and the outer intermediate tube is 30-100mm.

[0013] Preferably, the limiting ring plate and the displacement baffle are coaxially arranged, and the limiting ring plate is equidistant from the displacement baffles located on both sides.

[0014] Preferably, the inner tube assembly further includes an inner end tube located at the end of the inner corrugated tube away from the inner intermediate tube, and the outer tube assembly further includes an outer end tube located at the end of the outer corrugated tube away from the outer intermediate tube. The outer peripheral surface of the inner end tube is provided with a guide slide plate, which is annular and has a groove on its outer peripheral surface. A sliding piece is provided in the groove and abuts against the outer end tube.

[0015] Preferably, the inner diameter of the guide plate is welded to the inner end tube, the single-sided distance between the outer diameter of the guide plate and the inner diameter of the outer end tube is 3-5 mm, and the sliding plate is a PTFE sliding plate.

[0016] Preferably, the minimum distance between the guide slide and the inner bellows is 80-120 mm.

[0017] Preferably, there are two inner corrugated pipes located on both sides of the inner intermediate pipe, and two outer corrugated pipes located on both sides of the outer intermediate pipe.

[0018] Preferably, the self-limiting multi-directional flexible compensation structure for the double-walled pipe further includes a flow guide tube, which is disposed between the inner end pipe and the inner middle pipe and extends along the length of the inner middle pipe 6 to protect the inner corrugated pipe from media impact.

[0019] The present invention also discloses the application of the above-mentioned self-limiting multi-directional flexible compensation structure for double-walled tubes in a ship dual-fuel gas supply system.

[0020] Compared with existing technologies, the self-limiting multi-directional flexible compensation structure, method, and application for double-walled pipes described in this invention have the following beneficial effects: 1) By setting a limiting ring plate and a displacement baffle, the inner and outer corrugated pipes have limited and controllable relative displacement in the axial direction, rather than the traditional rigid synchronization, thus effectively avoiding the risk of overload of one corrugated pipe; 2) By setting a guide slide plate, the coaxiality of the inner and outer pipes during thermal expansion and contraction can be guaranteed, while allowing the inner and outer pipes to slide freely relative to each other in the axial direction to decouple the axial displacement constraints between them; 3) While achieving flexible compensation in the axial and radial directions, it is applicable to fully welded pipeline systems, solving the applicability problem of flange-connected integrated double-walled corrugated pipes in welding-dominated applications such as ships; it requires minimal modification to existing structures and is easy to implement. Attached Figure Description

[0021] Figure 1 This is a cross-sectional schematic diagram of the self-limiting multi-directional flexible compensation structure for double-walled tubes described in this invention;

[0022] Figure 2 This is an assembly cross-sectional view of the displacement baffle and the limiting ring plate described in this invention.

[0023] Explanation of reference numerals in the attached figures:

[0024] 1-Inner end tube; 2-Guide slide plate; 3-Outer end tube; 4-Inner corrugated pipe; 5-Outer corrugated pipe; 6-Inner intermediate pipe; 7-Outer intermediate pipe; 8-Flow guide tube; 9-Displacement baffle; 10-Limiting ring plate. Detailed Implementation

[0025] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Without conflict, the technical features of the embodiments of the present invention can be combined with each other.

[0026] With the widespread use of clean fuels such as liquefied natural gas in dual-fuel propulsion systems of ships, double-walled pipe designs are commonly adopted in gas supply pipelines to ensure transportation safety. The inner pipe transports cryogenic media, while the outer pipe forms a protective annular cavity. However, under prolonged low-frequency vibration conditions, the inner pipe contracts due to the cryogenic medium, while the outer pipe may expand due to ambient temperature or heat tracing, leading to reverse thermal displacement. If the stress generated by thermal expansion and contraction is not effectively released, it severely affects the pipeline's sealing performance and long-term operational safety. Therefore, the applicant proposes the following technical solution:

[0027] like Figure 1-2 As shown, a self-limiting multi-directional flexible compensation structure for double-walled pipes includes:

[0028] The inner tube assembly includes a connected inner corrugated pipe 4 and an inner intermediate pipe 6, wherein a displacement baffle 9 is provided on the outer wall of the inner intermediate pipe 6;

[0029] The outer tube assembly is coaxially sleeved on the outside of the inner tube assembly, including a connected outer corrugated tube 5 and an outer intermediate tube 7. The inner wall of the outer intermediate tube 7 is provided with a limiting ring plate 10 with a thickness of δ.

[0030] There are two displacement baffles 9 located on both sides of the limiting ring plate 10. The distance between the two displacement baffles 9 is L, where L = δ + 2X and X is 10 to 30 mm.

[0031] This design ensures that the inner intermediate pipe 6 and the outer intermediate pipe 7 can freely deflect laterally, while providing reliable mechanical limits for relative axial displacement to restrict the axial offset of both. This effectively solves the problem of uneven deformation of the inner and outer corrugated pipes caused by uneven thermal expansion and deformation in double-walled pipes, significantly reducing the risk of excessive deformation of one of the inner or outer corrugated pipes and extending its service life. When the displacement reaches its limit, the displacement baffle 9 will abut against the limiting ring plate 10 to limit the axial deformation of the inner corrugated pipe 4 and the outer corrugated pipe 5, greatly improving the service life and safety of the entire compensation structure. By limiting the relationship between the thickness of the displacement baffle 9 and the distance between the two displacement baffles 9, it ensures that the two do not contact each other within the normal thermal expansion and contraction range, preventing frequent friction and wear between components.

[0032] Preferably, the displacement baffle 9 is welded and fixed to the outer wall of the inner intermediate tube 6 and is annular, the single-sided distance between the displacement baffle 9 and the outer intermediate tube 7 is 10-20mm, the limiting ring plate 10 is welded and fixed to the inner wall of the outer intermediate tube 7, the single-sided distance between the limiting ring plate 10 and the inner intermediate tube 6 is 5-30mm, and the single-sided distance between the inner intermediate tube 6 and the outer intermediate tube 7 is 30-100mm.

[0033] This design actively allows and restricts the axial relative displacement between the inner and outer bellows by forming an asymmetrical limiting structure, allowing them to deform freely according to their own temperature. When the relative displacement reaches its limit, it is mechanically limited to prevent individual bellows from being overstretched or compressed, breaking the traditional mindset of synchronous deformation in compound bellows. Since the radial displacement of the outer intermediate pipe 7 is less than that of the inner intermediate pipe 6 under normal conditions, this design will not interfere with the slight radial displacement of the outer intermediate pipe 7 under normal conditions. It can also provide support after the outer intermediate pipe 7 undergoes a large radial displacement, while ensuring that the limiting ring plate 10 can always contact the displacement baffle 9 after the inner intermediate pipe 6 undergoes a large radial displacement under normal conditions, ensuring that the axial constraint effect does not fail.

[0034] As an example, the limiting ring plate 10 and the displacement baffle 9 are coaxially arranged, and the distance between the displacement baffles 9 on both sides of the limiting ring plate 10 is the same. This arrangement ensures that the displacement baffle 9 can make vertical and flat surface contact with the end face of the limiting ring plate 10, thereby distributing the impact force evenly along the axis of the pipeline, completely eliminating eccentric force caused by installation deviations or manufacturing tolerances, effectively preventing bending deformation or weld tearing of the limiting ring plate 10 caused by local stress concentration; it can effectively constrain the radial degree of freedom of the inner intermediate pipe 6, and provide uniform lateral support when the pipeline undergoes lateral micro-movement, resulting in a long service life.

[0035] As an example, the inner tube assembly further includes an inner end tube 1, which is located at the end of the inner corrugated tube 4 away from the inner intermediate tube 6. The outer tube assembly further includes an outer end tube 3, which is located at the end of the outer corrugated tube 5 away from the outer intermediate tube 7. The inner end tube 1 is provided with a guide slide plate 2, which is annular and has a groove on its outer circumference. A sliding piece is provided in the groove, and the sliding piece abuts against the outer end tube 3.

[0036] This design ensures the coaxiality of the inner end pipe 1 and the outer end pipe 3 during thermal expansion and contraction, while allowing them to slide freely relative to each other in the axial direction to decouple the axial displacement constraints of the inner and outer pipes. This effectively solves the problem of flexible compensation for both axial and radial thermal expansion displacements in double-walled pipes.

[0037] Preferably, the inner diameter of the guide plate 2 is welded to the inner end tube 1, and the single-sided distance between the outer diameter of the guide plate 2 and the inner diameter of the outer end tube 3 is 3-5mm.

[0038] This design allows the outer and inner pipes of the double-walled pipeline to undergo tensile or compressive compensation based on the actual temperature difference with the environment, rather than only compressing or stretching in one direction. This minimizes the temperature difference stress between the inner and outer pipes, ensuring the long-term safe operation of the double-walled pipeline system. By adding a sliding structure, the relative radial displacement of the inner bellows 4 and the outer bellows 5 can be controlled. Without affecting the tensile or compressive deformation of the inner bellows 4 and the outer bellows 5, the concentricity of the double-walled pipes can be maximized. This indirectly reduces the bending or shear stress of the circumferential weld caused by their misalignment, ensuring the long-term safe operation of the double-walled pipeline system.

[0039] Preferably, the minimum distance between the guide slide plate 2 and the inner bellows 4 is 80-120mm. This setting ensures that the inner bellows 4 can freely expand within its elastic limit, while the guide slide plate 2 can smoothly take over and guide subsequent linear motion, providing sufficient buffer margin for the axial compression, tension, and radial / angular deflection of the inner bellows 4; it also provides sufficient radial and axial operating clearance for subsequent welding operations, reducing assembly difficulty.

[0040] Preferably, the sliding plate is a PTFE sliding plate. Because PTFE has an extremely wide temperature tolerance range and does not become brittle at low temperatures, it ensures that the sliding plate maintains good low-friction characteristics in extreme cryogenic environments, allowing the inner and outer tubes to slide freely and smoothly relative to each other to release thermal stress; it can effectively resist media leakage or external environmental corrosion, while also absorbing energy from high-frequency vibrations to buffer and dampen shocks, extending the product's service life.

[0041] The outer wall surface of the guide slide plate 2 is provided with grooves for limiting the assembly of the sliding piece; there are multiple grooves and they are arranged at equal intervals along the outer periphery of the guide slide plate 2.

[0042] This design utilizes grooves to circumferentially and radially limit the sliding plates, ensuring they remain embedded within the predetermined track even when the double-walled tube experiences axial displacement due to thermal expansion and contraction. This prevents circumferential movement or detachment due to vibration or friction. The evenly spaced sliding plates ensure uniform distribution of support points for the inner end tube 1 and outer end tube 3, effectively absorbing and buffering vibration energy to prevent increased gaps or impact noise caused by vibration. The number of grooves can be adjusted according to the pressure of the internal medium and the diameter of the double-walled tube, preferably 8-12.

[0043] As an example, the sliding plate extends along the length direction of the inner end tube 1 and has a length and width of L1 and L2 respectively, wherein L1 = (1.05-1.10) × L2, and the thickness of the guide plate 2 is D, wherein L1 = (0.7-0.9) × D.

[0044] Since the support plate 9 is usually an annular plate, its thickness D represents the material's stiffness reserve. Limiting L1 to 0.7 to 0.9 times D effectively ensures the overall structural strength of the support plate, preventing breakage due to excessively wide slots. It also maximizes the contact area of ​​the sliding piece, ensuring the stability of the sliding contact between them. Since the length L1 is only 5% to 10% larger than the width L2, the circumferential dimension of the sliding piece is strictly limited so that its long side is arranged along the pipe axis when embedded in the groove, effectively preventing the sliding piece from rotating or tilting under circumferential stress. Since double-walled pipes often have a slight angular deflection at the same time as axial displacement during thermal expansion and contraction, this setting allows the sliding piece to have good mobility in both the axial and radial (circumferential) directions, making it less prone to jamming due to uneven stress caused by installation deviations or thermal deformation.

[0045] As an example, there are two inner bellows 4, located on either side of the inner intermediate tube 6, and two outer bellows 5, located on either side of the outer intermediate tube 7. This arrangement can double the total compensation by utilizing the superposition effect of multiple bellows structures, ensuring that the compensation structure can absorb ultra-long axial displacements caused by severe thermal expansion and contraction, thus preventing system failure; the flexible unit has a high degree of freedom and can absorb axial, lateral, and angular displacements, thereby perfectly coping with the complex three-dimensional spatial constraints and multi-dimensional dynamic loads in the ship's engine room.

[0046] As an example, the self-limiting multi-directional flexible compensation structure for the double-walled pipe also includes a flow guide tube 8, which is disposed between the inner end pipe 1 and the inner middle pipe 6 to protect the inner bellows 4 from media impact.

[0047] This design utilizes the guide tube 8 as a protective barrier between the medium and the inner bellows 4 to guide the medium to pass smoothly, avoiding direct impact of high-speed medium on the inner bellows 4, and significantly extending the service life of the entire compensation structure; at the same time, it restricts the disorderly flow of the medium at the inner bellows 4 to reduce pressure loss during transportation and improve the overall transportation efficiency of the pipeline system.

[0048] As an example of the present invention, there are two guide tubes 8, which are respectively located on both sides of the inner intermediate tube 6; wherein one end of the guide tube 8 located at the upstream end is welded to the inner end tube 1, and the other end abuts against the inner intermediate tube 6; one end of the guide tube 8 located at the downstream end abuts against the inner end tube 1, and the other end is welded to the inner intermediate tube 6.

[0049] This design provides ample axial sliding space for the guide tube 8. Regardless of thermal expansion and contraction of the pipeline, the guide tube can adapt to length changes through relative sliding at the contact end, thereby relieving the axial force on the guide tube 8 itself. This ensures that the medium is always confined within the guide tube 8 and flows smoothly, effectively preventing the inner bellows 4 from being impacted by fluid eddies and mechanically worn. It also ensures that the guide tube 8 and the inner intermediate pipe 6 always maintain extremely high coaxiality, thus enhancing the bending rigidity and operational stability of the entire compensation structure.

[0050] The present invention also provides a manufacturing process for the self-limiting multi-directional flexible compensation structure for the double-walled pipeline, comprising:

[0051] S1. Weld one displacement baffle 9 to the outer wall of the inner intermediate tube 6, weld a limiting ring plate 10 to the inner wall of the outer intermediate tube 7, fit the inner intermediate tube 6 into the outer intermediate tube 7, and then weld another displacement baffle 9 to the outer wall of the inner intermediate tube 6.

[0052] S2. Install the two inner corrugated pipes 4 at both ends of the inner intermediate pipe 6 respectively, and fully weld them to the inner end pipe 1 and the inner intermediate pipe 6 respectively; then place the two guide tubes 8 on both sides of the inner intermediate pipe 6 respectively, and fix them by welding one end and abutting the other end.

[0053] S3. Install the two outer corrugated pipes 5 at both ends of the outer intermediate pipe 7, and fully weld them to the outer end pipe 3 and the outer intermediate pipe 7 respectively.

[0054] S4. Weld the inner side of the guide slide plate 2 to the outer wall of the inner end tube 1; then fit the outer tube assembly and weld it to the self-limiting assembly, and ensure that the PTFE sliding piece embedded on the outside fits against the inner wall of the outer end tube 3.

[0055] This invention ensures that the stress at elbows and fixed points meets design requirements, while reducing the risk of weld cracking and fatigue cracking of the outer pipe under low-temperature alternating conditions, thus guaranteeing the safety of the pipeline system design. Since the integrated double-wall corrugated pipe must precisely match the axial stiffness of the inner and outer corrugated pipes, stiffness imbalance can lead to a series of overloads and failures. The synchronous tie rod scheme requires calculation of the tie rod preload, and selection errors can easily result in uneven loads. This application can lower the design selection threshold, ensure the design safety of the system, accept minor misalignments during on-site assembly and welding, and reduce production costs.

[0056] This invention also discloses the application of the self-limiting multi-directional flexible compensation structure for double-walled pipelines in marine dual-fuel gas supply systems. This invention can be applied to double-walled pipeline systems in dual-fuel powered ships and in the transportation of cryogenic media such as liquid hydrogen, liquid oxygen, and LNG. It can solve the problems of thermal expansion stress release and vibration absorption in double-walled pipelines with limited space and dimensions, and eliminates the problem of uneven deformation of the inner and outer corrugated pipes caused by uneven thermal expansion in double-walled pipelines. It can significantly reduce the risk of excessive deformation of one of the inner or outer corrugated pipes and extend their service life.

[0057] While the present invention has been disclosed above, it is not limited thereto. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the invention; therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. A self-limiting multi-directional flexible compensation structure for double-walled tubes, characterized in that, include: The inner tube assembly includes a connected inner corrugated pipe (4) and an inner intermediate pipe (6), wherein a displacement baffle (9) is provided on the outer wall of the inner intermediate pipe (6). The outer tube assembly is coaxially sleeved on the outside of the inner tube assembly, including a connected outer corrugated pipe (5) and an outer intermediate pipe (7). The inner wall of the outer intermediate pipe (7) is provided with a limiting ring plate (10) with a thickness of δ. There are two displacement baffles (9) located on both sides of the limiting ring plate (10). The distance between the two displacement baffles (9) is L, where L = δ + 2X and X is 10 to 30 mm.

2. The self-limiting multi-directional flexible compensation structure for double-walled tubes according to claim 1, characterized in that, The displacement baffle (9) is welded and fixed to the outer wall of the inner intermediate tube (6) and is in the shape of a ring. The distance between the displacement baffle (9) and the outer intermediate tube (7) is 10-20 mm. The limiting ring plate (10) is welded and fixed to the inner wall of the outer intermediate tube (7). The distance between the limiting ring plate (10) and the inner intermediate tube (6) is 5-30 mm. The distance between the inner intermediate tube (6) and the outer intermediate tube (7) is 30-100 mm.

3. The self-limiting multi-directional flexible compensation structure for double-walled tubes according to claim 2, characterized in that, The limiting ring plate (10) and the displacement baffle (9) are coaxially arranged, and the limiting ring plate (10) is at the same distance from the displacement baffle (9) located on both sides.

4. The self-limiting multi-directional flexible compensation structure for double-walled tubes according to claim 1, characterized in that, The inner tube assembly further includes an inner end tube (1), which is located at the end of the inner corrugated tube (4) away from the inner intermediate tube (6). The outer tube assembly further includes an outer end tube (3), which is located at the end of the outer corrugated tube (5) away from the outer intermediate tube (7). A guide plate (2) is provided on the outer peripheral surface of the inner end tube (1). The guide plate (2) is annular and has a groove on its outer peripheral surface. A sliding piece is provided in the groove and abuts against the outer end tube (3).

5. The self-limiting multi-directional flexible compensation structure for double-walled tubes according to claim 4, characterized in that, The inner diameter of the guide slide plate (2) is welded to the inner end tube (1), and the single-sided distance between the outer diameter of the guide slide plate (2) and the inner diameter of the outer end tube (3) is 3-5 mm. The sliding plate is a PTFE sliding plate.

6. The self-limiting multi-directional flexible compensation structure for double-walled tubes according to claim 4 or 5, characterized in that, The minimum distance between the guide slide plate (2) and the inner bellows (4) is 80-120 mm.

7. The self-limiting multi-directional flexible compensation structure for double-walled tubes according to claim 4, characterized in that, There are two inner corrugated pipes (4) located on both sides of the inner intermediate pipe (6), and there are two outer corrugated pipes (5) located on both sides of the outer intermediate pipe (7).

8. The self-limiting multi-directional flexible compensation structure for double-walled tubes according to claim 7, characterized in that, The self-limiting multi-directional flexible compensation structure for the double-walled pipe also includes a flow guide (8), which is disposed between the inner end pipe (1) and the inner middle pipe (6) and extends along the length direction of the inner middle pipe (6) to protect the inner corrugated pipe (4) from the impact of the medium.

9. The application of the self-limiting multi-directional flexible compensation structure for double-walled pipes as described in any one of claims 1-8 in a ship dual-fuel gas supply system.

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