A pressure test system and test method for a cryogenic liquid cargo tank

Abstract

This invention discloses a pressure testing system and method for cryogenic liquid cargo storage tanks, relating to the field of testing cryogenic liquid cargo storage and transportation equipment. The system includes a base, a testing unit, a hydraulic chamber, and a pressurizing device. The base is a circular base plate; the testing unit is circular and, from bottom to top, includes a secondary insulation layer, a secondary shielding layer, a primary insulation layer, and a primary shielding layer. The testing unit is clamped between the hydraulic chamber and the base. The hydraulic chamber includes a rigid outer wall and an elastic inner liner. A fixed flange is installed at the lower end of the rigid outer wall, and the fixed flange is connected to the base plate by multiple double-ended bolts. The upper end of the rigid outer wall is sealed by a flange cover. One end of the elastic inner liner is sealed and welded to the primary shielding layer, and the other end is sealed by a sealing plate to form a pressurized chamber. The pressurizing device passes through the sealing plate and connects to the pressurized chamber. During testing, pressurized liquid is injected into the elastic inner liner. The testing unit is compressed under pressure, and the elastic inner liner correspondingly elongates, ensuring uniform stress on the testing unit and accurately testing the ultimate pressure-bearing capacity of the cryogenic liquid cargo storage tank.

Description

Technical Field

[0001] This invention relates to the field of testing technology for cryogenic liquid cargo storage and transportation equipment, specifically to a pressure testing system and method for cryogenic liquid cargo storage tanks. Background Technology

[0002] Cryogenic liquid cargo storage tanks are storage and transportation equipment used to store cryogenic liquid cargoes such as liquefied natural gas, liquefied ethylene, and liquefied petroleum gas. Their operating temperature is usually as low as -160℃. The pressure bearing capacity of cryogenic liquid cargo storage tanks directly determines their safety and service life. Therefore, their pressure bearing capacity needs to be tested before they are put into use to verify whether the deformation characteristics, load bearing capacity and sealing performance of cryogenic liquid cargo storage tanks under design pressure meet the requirements.

[0003] In existing technologies, pressure testing of cryogenic liquid cargo storage tanks typically employs simulation chambers. A simulation chamber is a specialized test container manufactured to scale or full size according to a portion of the actual tank's structure. The pressure exerted on the cryogenic liquid cargo storage tank by simulating the sloshing of liquid within the chamber is used to test its pressure resistance. However, using simulation chambers for pressure testing has several drawbacks: First, the structure of simulation chambers is complex, requiring a complete replication of the multi-layered structure of the cryogenic liquid cargo storage tank and the connections between each layer, resulting in long manufacturing cycles and high processing difficulty. Second, the manufacturing cost of simulation chambers is high; full-size simulation chambers are expensive, and one simulation chamber typically corresponds to only one type of tank, lacking versatility and being difficult to reuse after testing, leading to resource waste. Third, the liquid loading capacity of the simulation chamber is limited; even with the added effect of sloshing, the pressure experienced by the cryogenic liquid cargo storage tank is limited, making it unsuitable for testing the ultimate pressure resistance of the cryogenic liquid cargo storage tank's containment system. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a pressure testing system and method for cryogenic liquid cargo storage tanks, so as to solve the technical problems of existing simulated tanks having complex structures, high costs, and being inconvenient for testing the ultimate pressure bearing capacity of cryogenic liquid cargo storage tanks.

[0005] To address the aforementioned technical problems, this invention provides a pressure testing system for cryogenic liquid cargo storage tanks, comprising: The base is a circular base plate; The test unit is a circle that matches the shape of the base plate. The test unit is placed on the base plate. The test unit includes, from bottom to top, a secondary insulation layer, a secondary shielding layer, a primary insulation layer, and a primary shielding layer. The secondary insulation layer includes a secondary polyurethane block and a secondary outer plywood and a secondary inner plywood that hold the secondary polyurethane block in place. The secondary shielding layer is provided with a first corrugation that protrudes towards the base plate. A hydraulic chamber is positioned above the test unit, which is clamped between the hydraulic chamber and the base. The hydraulic chamber includes a rigid outer wall and an elastic inner liner. A fixed flange is provided on the outer periphery of the lower end of the rigid outer wall. The fixed flange and the base plate are connected by multiple double-ended screws. The length of the double-ended screws is greater than the original thickness of the test unit. The two ends of the double-ended screws pass through the fixed flange and the base plate respectively and are locked by nuts. The upper end of the rigid outer wall is sealed by a flange cover. The elastic inner liner can extend and retract axially. One end of the elastic inner liner is sealed and welded to the main shielding layer, and the other end is sealed by a sealing plate. The elastic inner liner, the sealing plate, and the main shielding layer together form a sealed pressurized chamber. A pressure-pressuring device that passes through the sealing plate and connects to the pressure chamber.

[0006] Furthermore, the test unit is formed by cutting the cryogenic liquid cargo storage tank.

[0007] Furthermore, the main shielding layer is provided with a first main corrugation that protrudes toward the hydraulic chamber.

[0008] Furthermore, the main shielding layer is provided with a second main corrugation that protrudes toward the base plate.

[0009] Furthermore, the secondary shielding layer is also provided with a second corrugation protruding toward the hydraulic chamber. The second corrugation is arranged along the extension direction of the first corrugation, and the first corrugation and the second corrugation are connected by a transition section.

[0010] Furthermore, the main shielding layer is provided with a first main corrugation protruding towards the hydraulic chamber and a second main corrugation protruding towards the base plate. The second main corrugation is provided along the extension direction of the first main corrugation, and the first main corrugation and the second main corrugation are connected by a transition section.

[0011] Furthermore, the main insulation layer is composed of main plywood.

[0012] Furthermore, the test unit also includes a support wall located on the side close to the base plate, and a resin mortar is disposed between the support wall and the secondary insulation layer.

[0013] Furthermore, the elastic inner liner is a metal corrugated pipe.

[0014] Furthermore, at least four double-ended screws are provided, which are evenly distributed around the circumference of the hydraulic chamber, and supports are connected to the outer sides of the base plate and the flange cover.

[0015] Furthermore, the test unit is coaxially arranged with the base via a positioning structure.

[0016] Furthermore, it also includes a pressure gauge, which is connected to the pressurization chamber.

[0017] This invention also provides a pressure testing method for cryogenic liquid cargo storage tanks, employing the aforementioned pressure testing system for cryogenic liquid cargo storage tanks, and comprising the following steps: S10: Cut the cryogenic liquid cargo storage tank to form a test unit, place the test unit on the base, and make the test unit from bottom to top consist of a secondary insulation layer, a secondary shielding layer, a primary insulation layer and a primary shielding layer. S20: Connect the pressure device to the inside of the elastic inner liner, and then place the hydraulic chamber cover on top of the test unit. First, seal and weld the elastic inner liner to the main shielding layer, and then fit the rigid outer wall over the elastic inner liner. At the same time, connect the rigid outer wall to the base plate through a double-headed screw, and keep the distance between the hydraulic chamber and the base at the original thickness of the test unit. S30: Pressurized liquid is injected into the elastic inner liner through a pressurizing device. The test unit is compressed and its thickness decreases, and the elastic inner liner elongates accordingly. S40: The pressure inside the pressurization chamber is detected by a pressure gauge, and the thickness change of the test unit is measured to complete the test of the pressure-bearing capacity of the test unit.

[0018] The beneficial effects of this invention are: (1) The present invention can test the pressure bearing capacity of the enclosure system of cryogenic liquid cargo storage tank by means of the base, test unit, hydraulic chamber and pressure device. The test system has a simple structure and does not require the manufacture of a full-size simulation chamber with a complex structure and high cost, which significantly reduces the manufacturing cost and processing difficulty of the test system. After the test is completed, each component can be reused and has good versatility. (2) The test unit of the present invention is formed by cutting a cryogenic liquid cargo storage tank. The test unit is a real sample of the actual storage tank enclosure system. Its material, thickness of each layer, corrugated structure and interlayer connection relationship are completely consistent with the actual storage tank. The test results can reflect the pressure bearing capacity of the actual storage tank enclosure system in a true and accurate manner. (3) The present invention provides an elastic inner liner in the hydraulic chamber. One end of the elastic inner liner is sealed and welded to the main shielding layer, and the other end is sealed by a sealing plate. During the test, pressurized liquid is injected into the elastic inner liner. The test unit is compressed and its thickness decreases. The elastic inner liner elongates accordingly, so that the test unit is uniformly pressurized on the entire force surface. This can truly reflect the pressure state of the test unit under actual working conditions and facilitate the testing of the ultimate pressure bearing capacity of the cryogenic liquid cargo storage tank enclosure system. (4) The present invention connects the rigid outer wall and the base plate by means of a double-headed screw. The length of the double-headed screw is greater than the original thickness of the test unit, and the distance between the hydraulic chamber and the base is the original thickness of the test unit. This allows the test unit to be in a natural, unpressurized state when it is not pressurized, thus avoiding additional pre-pressurization deformation of the test unit during assembly and ensuring the accuracy of the test results. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 This is a schematic diagram of a test unit embodiment of the present invention; Figure 3 This is a cross-sectional view of the hydraulic chamber of the present invention; Figure 4 This is a schematic diagram of the test unit embodiment two of the present invention; Figure 5 This is a schematic diagram of the test unit of the present invention, embodiment three; Figure 6 This is a schematic diagram of the test unit of the present invention, embodiment four; Figure 7 This is a schematic diagram of the fifth embodiment of the test unit of the present invention.

[0020] Explanation of the labels in the diagram: 10. Base; 11. Base plate; 12. Support; 20. Test unit; 21. Secondary insulation layer; 211. Secondary polyurethane block; 212. Secondary outer plywood; 213. Secondary inner plywood; 22. Secondary shielding layer; 221. First corrugation; 222. Second corrugation; 23. Main insulation layer; 231. Main plywood; 24. Main shielding layer; 241. First main corrugation; 242. Second main corrugation; 25. Support wall; 251. Resin putty; 30. Hydraulic chamber; 31. Rigid outer wall; 311. Fixed flange; 312. Double-ended screw; 313. Flange cover; 32. Elastic inner liner; 321. Sealing plate. Detailed Implementation

[0021] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.

[0022] Reference Figure 1The diagram shows the overall structure of the pressure testing system for cryogenic liquid cargo storage tanks according to the present invention. The pressure testing system for cryogenic liquid cargo storage tanks provided by the present invention includes a base 10, a testing unit 20, a hydraulic chamber 30, and a pressure-pressuring device. The base 10 supports the testing unit 20, providing a flat and stable support foundation for the testing unit 20. The testing unit 20 is a layered structure sample of the cryogenic liquid cargo storage tank to be tested, which, from bottom to top, includes a secondary insulation layer 21, a secondary shielding layer 22, a primary insulation layer 23, and a primary shielding layer 24. The hydraulic chamber 30 is located above the testing unit 20, cooperating with the base 10 to clamp the testing unit 20 within it. An elastic inner liner 32 is provided inside the hydraulic chamber 30, and pressure is applied to the testing unit 20 by injecting pressurized liquid into the elastic inner liner 32. The pressure-pressuring device passes through the sealing plate 321 of the elastic inner liner 32 and connects to the pressurizing chamber, used to inject pressurized liquid into the pressurizing chamber.

[0023] Specifically, in this embodiment, the base 10 is a circular base plate 11, which is used to support the test unit 20. Its upper surface is a flat support surface, and the test unit 20 is placed on the upper surface of the circular base plate 11. The diameter of the circular base plate 11 is not less than the outer diameter of the test unit 20, so that the entire bottom surface of the test unit 20 is supported by the circular base plate 11, thus preventing the test unit 20 from being suspended.

[0024] The circular base plate 11 is made of a material with high rigidity, such as steel plate or thick-walled metal plate. During the test, the test unit 20 is compressed and transmits the pressure to the circular base plate 11. The circular base plate 11 must remain flat and not undergo significant bending deformation to ensure that the bottom surface of the test unit 20 is uniformly stressed. The thickness of the circular base plate 11 is determined according to the maximum pressure that the test unit 20 needs to withstand to ensure that the circular base plate 11 still has sufficient rigidity under the maximum test pressure.

[0025] Reference Figure 2As shown, the test unit 20 is formed by cutting a cryogenic liquid cargo storage tank. It is circular, matching the shape of the base plate 11. The test unit 20 is placed on the base plate 11 and, from bottom to top, includes a secondary insulation layer 21, a secondary shielding layer 22, a primary insulation layer 23, and a primary shielding layer 24. This makes the test unit 20 a true sample of the actual cryogenic liquid cargo storage tank, and the test results can accurately reflect the pressure-bearing capacity of the actual tank enclosure system. During cutting, the cryogenic liquid cargo storage tank is circularly cut along a direction perpendicular to the plane of the enclosure system. The cutting line penetrates all layers of the enclosure system, including the primary shielding layer 24, the primary insulation layer 23, the secondary shielding layer 22, and the secondary insulation layer 21. If necessary, a support wall 25 is also included. The resulting test unit 20 is a disc-shaped sample. The circle is a centrally symmetrical figure with high geometric symmetry, and its circumference has completely consistent boundary conditions. When the test unit 20 is circular, it is coaxially fitted with the equally circular base 10, hydraulic chamber 30, and elastic inner liner 32. The pressure applied to the test unit 20 by the pressurized liquid through the elastic inner liner 32 is axially symmetrically distributed along the circumference of the test unit 20. The stress state at all points of the test unit 20 is symmetrical and consistent, thus ensuring that the test unit 20 is uniformly pressurized throughout the entire area. In addition, the circular structure does not have the sharp corners of rectangular or square specimens, avoiding stress concentration and non-uniform deformation caused by boundary constraints at the corners of the test unit 20.

[0026] In test unit 20, the secondary insulation layer 21 is located at the bottom and is placed directly on the upper surface of the circular base plate 11. The secondary insulation layer 21 includes a secondary polyurethane block 211 and a secondary outer plywood 212 and a secondary inner plywood 213 that hold the secondary polyurethane block 211 within it. The secondary polyurethane block 211 is the main insulation material of the secondary insulation layer 21. Due to the presence of the secondary polyurethane block 211, the test unit 20 can be deformed by compression. The secondary shielding layer 22 is laid on the side of the secondary insulation layer 21 facing away from the base plate 11. The secondary shielding layer 22 is a corrugated metal film plate with corrugations on its surface. In this embodiment, the secondary shielding layer 22 is provided with a first corrugation 221 that protrudes towards the base plate 11, that is, towards the direction of the secondary insulation layer 21. The arrangement of the first corrugation 221 protruding towards the base plate 11 eliminates the need to set a large number of clearance positions on the outer surface of the main insulation layer 23, thereby improving the integrity of the main insulation layer 23.

[0027] The main insulation layer 23 is laid on the side of the secondary shielding layer 22 away from the secondary insulation layer 21. The main shielding layer 24 is located at the top of the test unit 20 and is a corrugated metal film plate that directly contacts the liquid. The surface of the main shielding layer 24 is corrugated. During testing, the elastic inner liner 32 is sealed and welded to the main shielding layer 24, and the pressure of the pressurized liquid acts directly on the main shielding layer 24. In the first embodiment of the present invention, the main shielding layer 24 is provided with a first main corrugation 241 protruding towards the hydraulic chamber 30, that is, away from the main insulation layer 23, so that it is not necessary to set a large number of clearance positions on the inner side of the main insulation layer 23, thus ensuring the integrity of the main insulation layer 23.

[0028] Reference Figure 3 The diagram shows a cross-sectional view of the hydraulic chamber 30 of the present invention. The hydraulic chamber 30 is disposed above the test unit 20, which is clamped between the hydraulic chamber 30 and the base 10. The hydraulic chamber 30 includes a rigid outer wall 31 and an elastic inner liner 32. The rigid outer wall 31 is a rigid shell of the hydraulic chamber 30, used to confine pressure within the hydraulic chamber 30. The rigid outer wall 31 is made of metal and has sufficient strength and rigidity to withstand the maximum pressure required for testing without significant deformation. The upper end of the rigid outer wall 31 is sealed by a flange cover 313, which is fixedly connected to the upper end of the rigid outer wall 31 by bolts or welding. The rigid outer wall 31 encloses an internal cavity, within which the elastic inner liner 32 is disposed. The elastic inner liner 32, disposed inside the rigid outer wall 31, is a flexible pressure-bearing component of the hydraulic chamber 30. One end of the elastic inner liner 32 is sealed and welded to the main shielding layer 24, and the other end of the elastic inner liner 32 is sealed by a sealing plate 321, which abuts against the flange cover 313. The elastic inner liner 32, the sealing plate 321, and the main shielding layer 24 together form a closed pressurized chamber. The pressurized chamber is a closed space that contains pressurized liquid. The pressurized liquid is filled into the pressurized chamber, and the pressure is evenly transmitted to the main shielding layer 24 through the elastic inner liner 32.

[0029] It should be noted that the elastic inner liner 32 and the main shielding layer 24 are connected by a sealed welding. The other end of the elastic inner liner 32 is sealed by a sealing plate 321, thereby isolating the pressurized liquid from the rigid outer wall 31. The pressure of the pressurized liquid only acts on the main shielding layer 24 through the elastic inner liner 32. The rigid outer wall 31 does not directly contact the pressurized liquid, thus avoiding corrosion of the rigid outer wall 31 by the pressurized liquid and ensuring the sealing of the pressurization chamber.

[0030] Specifically, in this embodiment, the elastic inner liner 32 is a metal bellows, which has excellent axial expansion and contraction capabilities, allowing it to lengthen or shorten with changes in axial length. The use of a metal bellows in the elastic inner liner 32 serves two purposes: firstly, it utilizes the axial expansion and contraction capabilities of the bellows to accommodate changes in the thickness of the test unit 20 during compression; secondly, it utilizes the radial confinement capabilities of the bellows to ensure that the pressure of the pressurized liquid is primarily applied to the main shielding layer 24, preventing leakage to the surrounding areas. One end of the elastic inner liner 32 is sealed and welded to the main shielding layer 24, and the other end of the elastic inner liner 32 is sealed by a sealing plate 321. The sealing plate 321 is a sealing element covering the end face of the other end of the elastic inner liner 32. Thus, the elastic inner liner 32, the sealing plate 321, and the main shielding layer 24 together form a sealed pressurized chamber, preventing leakage of the pressurized liquid inside.

[0031] During testing, pressurized liquid is injected into the elastic inner liner 32. The test unit 20 is compressed and its thickness decreases under pressure, while the elastic inner liner 32 elongates accordingly. The elastic inner liner 32 ensures that the test unit 20 experiences uniform stress throughout during pressurization. If the corrugated elastic inner liner 32 is not used, and the pressurized liquid is directly injected into the space between the hydraulic chamber 30 and the main shielding layer 24, the thickness of the central area of ​​the test unit 20 decreases under pressure during pressurization. However, the outer periphery of the test unit 20 cannot deform freely due to the constraint of the rigid outer wall 31, resulting in deformation at the edge of the chamber. Specifically, when the thickness of the central area of ​​the test unit 20 decreases, the central area of ​​the main shielding layer 24 sinks accordingly, while the edge area of ​​the main shielding layer 24 cannot sink due to its proximity to the rigid outer wall 31. This results in a non-uniform deformation on the main shielding layer 24 that gradually changes from the center to the edge. The compression amount of the test unit 20 is inconsistent throughout, and the stress distribution is uneven, failing to accurately reflect the uniform pressure state of the test unit 20 under actual working conditions. With the corrugated inner liner 32 installed, when pressurized liquid is filled into the corrugated tube, the corrugated tube elongates as the test unit 20 is compressed. The end of the elastic inner liner 32 welded to the main shielding layer 24 always moves downward synchronously with the sinking of the main shielding layer 24, ensuring that the pressure of the pressurized liquid is always evenly applied to the area of ​​the main shielding layer 24 covered by the elastic inner liner 32. Since the elastic inner liner 32 covers the entire stress area of ​​the main shielding layer 24, the force of the pressurized liquid on the main shielding layer 24 is evenly distributed throughout the stress area, thus ensuring that the test unit 20 is uniformly pressurized across the entire stress surface. In this way, the compression deformation of the test unit 20 is uniform across the entire area, avoiding abnormal deformation at the edge of the chamber, thereby accurately reflecting the pressure-bearing state of the test unit 20 under actual working conditions, and facilitating the testing of the ultimate pressure-bearing capacity of the cryogenic liquid cargo storage tank enclosure system.

[0032] When pressurized liquid is injected into the elastic inner liner 32, the elastic inner liner 32 elongates axially. To limit the reverse elongation of the elastic inner liner 32 towards the test unit 20, a fixing flange 311 is provided on the outer periphery of the lower end of the rigid outer wall 31. The fixing flange 311 extends circumferentially along the rigid outer wall 31, and a through hole is provided on the fixing flange 311 for the double-ended screws 312 to pass through. The fixing flange 311 and the base plate 11 are connected by multiple double-ended screws 312. The length of the double-ended screws 312 is greater than the original thickness of the test unit 20. The two ends of the double-ended screws 312 pass through the fixing flange 311 and the base plate 11 respectively and are then locked with nuts. The so-called original thickness of the test unit 20 refers to the thickness formed by the natural superposition of the layers of the test unit 20 when it is not subjected to any external pressure. The length of the double-ended screw 312 is greater than the original thickness of the test unit 20 to allow both ends of the double-ended screw 312 to pass through the fixing flange 311 and the base plate 11 respectively, leaving thread allowance at both ends of the double-ended screw 312 for screwing in nuts. After both ends of the double-ended screw 312 pass through the through holes on the fixing flange 311 and the base plate 11 respectively, nuts are screwed into both ends of the double-ended screw 312 and locked, thereby fixing the rigid outer wall 31 to the base plate 11. By adjusting the screwing position of the nuts on the double-ended screw 312, the distance between the fixing flange 311 and the base plate 11 can be precisely adjusted so that this distance is not less than the original thickness of the test unit 20, that is, the test unit 20 is in a natural, unpre-compressed state. The purpose of this setting is to avoid the test unit 20 being subjected to additional pre-compressed deformation during assembly, ensuring that the test unit 20 is in a natural state before the pressure test begins, so that the test results can accurately reflect the true deformation characteristics of the test unit 20 under pressure. Meanwhile, due to the constraint of the nut, even if the elastic inner liner 32 pushes the rigid outer wall 31 upward under the action of pressurized liquid, it will not increase the distance between the rigid outer wall 31 and the base plate 11, thus affecting the measurement of the deformation of the test unit 20.

[0033] Due to the high pressure provided by the pressurized liquid, at least four double-ended screws 312 are provided to ensure a stable connection. These screws 312 are evenly distributed circumferentially around the hydraulic chamber 30. This ensures, on the one hand, that the connection force between the rigid outer wall 31 and the base plate 11 is evenly distributed, preventing the hydraulic chamber 30 from being tilted due to balanced force; on the other hand, it ensures that the distance between the rigid outer wall 31 and the base plate 11 is uniform throughout the circumference, ensuring consistent clamping conditions at all points on the test unit 20. To facilitate the installation of the double-ended screws 312, supports 12 are connected to the outer sides of both the base plate 11 and the flange cover 313. The outer side of the base plate 11 is the side facing away from the test unit 20, and the outer side of the flange cover 313 is the side facing away from the hydraulic chamber 30. The supports 12 elevate the base plate 11 to a certain height, facilitating the extension of the double-ended screws 312 and their engagement with the nuts.

[0034] The pressure testing system in this embodiment also includes a pressurization device. This device passes through the sealing plate 321 and connects to the pressurization chamber, where it is used to inject pressurized liquid. The pressurized liquid can be water or other inert liquid. The pressurization device can be a manual or electric pressurization pump. It is connected to the pressurization chamber via a pipe passing through the sealing plate 321, and a one-way valve or shut-off valve is installed on the pipe to prevent backflow of the pressurized liquid. Furthermore, the pressure testing system also includes a pressure gauge connected to the pressurization chamber to detect the pressure within the chamber. The pressure gauge can be a mechanical pressure gauge or an electronic pressure sensor. The pressure gauge is also connected to the pressurization chamber via a pressure measurement interface on the sealing plate 321 to monitor the pressure within the chamber in real time.

[0035] Reference Figure 4 The diagram shown is a schematic representation of the test unit 20 in Embodiment 2 of the present invention. In this embodiment, the corrugations on the secondary shielding layer 22 are first corrugations 221 that protrude towards the base plate 11, and the main shielding layer 24 is provided with second main corrugations 242 that protrude towards the base plate 11. That is, the second main corrugations 242 protrude towards the direction of the main insulation layer 23, and the protruding portion of the second main corrugations 242 faces the main insulation layer 23 and is supported by the main insulation layer 23, thereby preventing the corrugation protrusion from being suspended and improving the load-bearing capacity of the main shielding layer 24.

[0036] Reference Figure 5 The diagram shows a schematic of the test unit 20 in Embodiment 3 of the present invention. In this embodiment, the main shielding layer 24 is provided with a second main corrugation 242 protruding towards the base plate 11. The secondary shielding layer 22, in addition to the first corrugation 221 protruding towards the base plate 11, is also provided with a second corrugation 222 protruding towards the hydraulic chamber 30. The second corrugation 222 is arranged along the extension direction of the first corrugation 221, meaning that the second corrugation 222 and the first corrugation 221 are two segments of the same secondary corrugation, connected by a transition section. Specifically, the first corrugation 221 protrudes towards the base plate 11, and the second corrugation 222 protrudes towards the hydraulic chamber 30. The protrusion directions of the two corrugations are opposite. The transition section is a smooth transition portion connecting the peaks of the first corrugation 221 and the second corrugation 222, allowing the corrugations on the surface of the secondary shielding layer 22 to smoothly transition from protruding towards the base plate 11 to protruding towards the hydraulic chamber 30. This bidirectional alternating convex corrugated structure cuts off the space corresponding to the corrugation position of the secondary shielding layer 22, thereby preventing the protective gas from smoothly generating convection in the corrugated space and reducing liquid evaporation loss.

[0037] Reference Figure 6The diagram shown is a schematic representation of the test unit 20 in Embodiment 4 of the present invention. In this embodiment, the secondary shielding layer 22 includes a first corrugation 221 protruding towards the base plate 11 and a second corrugation 222 protruding towards the hydraulic chamber 30. Simultaneously, the main shielding layer 24 is also provided with a first main corrugation 241 protruding towards the hydraulic chamber 30 and a second main corrugation 242 protruding towards the base plate 11. This results in the corrugation space between the secondary shielding layer 22 and the main insulation layer 23, as well as the corrugation space between the main shielding layer 24 and the main insulation layer 23, being interrupted, further blocking the convection of the protective gas.

[0038] Reference Figure 7 The diagram shows a schematic of the test unit 20 in Embodiment 5 of the present invention. In this embodiment, the main shielding layer 24 is provided with a first main corrugation 241 protruding towards the hydraulic chamber 30, and the secondary shielding layer 22 is provided with a first corrugation 221 protruding towards the base plate 11 and a second corrugation 222 protruding towards the hydraulic chamber 30. Furthermore, unlike the secondary insulation layer 21 which uses a polyurethane block and plywood sandwich structure, the main insulation layer 23 in this embodiment only uses a main plywood 231, meaning the main insulation layer 23 is a single-layer plywood structure. Plywood has good structural strength and stability in low-temperature environments, and there is no interface between the polyurethane and the plywood. At low temperatures of around -160℃, the thermal expansion coefficients of the polyurethane material and the plywood material differ, and the interface between them is prone to debonding during repeated cooling and expansion. The main insulation layer 23 uses only the main plywood 231, which avoids the interface between polyurethane and plywood, fundamentally eliminating the risk of interface debonding under low temperature conditions and improving the structural reliability of the main insulation layer 23 in low temperature environment.

[0039] Furthermore, the test unit 20 may also include a support wall 25, located on the side closest to the base plate 11. The support wall 25 is the load-bearing wall of the cryogenic liquid cargo storage tank, situated outside the secondary insulation layer 21 in the enclosure system, bearing the entire load of the enclosure system and the liquid cargo inside. A resin putty 251 is disposed between the support wall 25 and the secondary insulation layer 21. The resin putty 251 is a leveling and bonding material filled between the support wall 25 and the secondary insulation layer 21. The test unit 20, including the support wall 25 and the resin putty 251, completely encompasses all components of the actual storage tank enclosure system. During testing, pressure is transmitted through the secondary insulation layer 21 to the resin putty 251, then to the support wall 25, and finally borne by the base 10, realistically replicating the complete force path of the actual storage tank enclosure system.

[0040] Furthermore, to ensure that the test unit 20 is centered on the base plate 11, the test unit 20 is coaxially positioned with the base 10 via a positioning structure. The positioning structure can take the form of a positioning boss, positioning ring, or positioning scale line on the upper surface of the circular base plate 11. The function of the positioning structure is to keep the test unit 20 coaxial with the base 10 and the hydraulic chamber 30, ensuring that the area covered by the elastic inner liner 32 is centered on the test unit 20. This allows the pressure of the pressurized liquid to be evenly applied to the central area of ​​the test unit 20, preventing uneven force distribution due to the eccentric placement of the test unit 20.

[0041] The pressure testing method for cryogenic liquid cargo storage tanks of the present invention, using the aforementioned pressure testing system, includes the following steps: S10: The cryogenic liquid cargo storage tank is cut to form a test unit 20. The test unit 20 is placed on the base 10, with the test unit 20 consisting of a secondary insulation layer 21, a secondary shielding layer 22, a primary insulation layer 23, and a primary shielding layer 24 from bottom to top. During cutting, a circular cut is made to the storage tank along a direction perpendicular to the plane of the enclosure system, with the cut line penetrating all layers of the enclosure system to form a disc-shaped test unit 20. During placement, the test unit 20 is coaxially positioned with the base 10 using the positioning structure on the base 10.

[0042] S20: Connect the pressure testing device to the interior of the elastic inner liner 32, and then place the hydraulic chamber 30 over the test unit 20, so that the elastic inner liner 32 is sealed and welded to the main shielding layer 24. At the same time, connect the rigid outer wall 31 to the base plate 11 through the double-ended screw 312, and keep the distance between the hydraulic chamber 30 and the base 10 at the original thickness of the test unit 20. In specific operation, one end of the elastic inner liner 32 is first sealed by the sealing plate 321, and the pressure testing device is connected to the pressure chamber through the sealing plate 321. Then, one end of the elastic inner liner 32 is sealed and welded to the main shielding layer 24 through the sealing weld. Then, the rigid outer wall 31 is fitted over the elastic inner liner 32, and the two ends of the double-ended screw 312 are respectively passed through the through holes on the fixing flange 311 and the base plate 11. By adjusting the screwing position of the nut, the distance between the hydraulic chamber 30 and the base 10 is exactly equal to the original thickness of the test unit 20. Finally, tighten the nut.

[0043] S30: Pressurized liquid is injected into the elastic inner liner 32 through the pressurization device. The test unit 20 is compressed and its thickness decreases, and the elastic inner liner 32 elongates accordingly. During the pressurization process, the pressure of the pressurized liquid is evenly applied to the main shielding layer 24 through the elastic inner liner 32. The test unit 20 undergoes compression deformation and its thickness decreases. The elastic inner liner 32 elongates synchronously with the compression of the test unit 20, ensuring that the pressurized liquid always acts evenly on the main shielding layer 24.

[0044] S40: The pressure inside the pressurization chamber is detected by a pressure gauge, and the thickness change of the test unit 20 is measured to complete the pressure-bearing capacity test of the test unit 20. During the test, the pressure of the pressurized liquid is gradually increased, and the thickness change of the test unit 20 at each pressure level is recorded to obtain the pressure-deformation relationship curve of the test unit 20. Based on this, the pressure-bearing capacity of the test unit 20 is evaluated, including whether the deformation of the test unit 20 under the design pressure meets the requirements, and whether the test unit 20 is damaged or leaks under the ultimate pressure.

[0045] The pressure testing system of this invention can also be used to test the ultimate pressure bearing capacity of cryogenic liquid cargo storage tanks. During the test, the pressure of the pressurized liquid is continuously increased until the test unit 20 is damaged or leaks. The pressure at this point is the ultimate pressure bearing capacity of the test unit 20. Because the elastic inner liner 32 allows the test unit 20 to expand and contract during pressurization, the test unit 20 is uniformly deformed under pressure across its entire width. The pressure corresponding to its damage or leakage can accurately reflect the ultimate pressure bearing capacity of the test unit 20, avoiding the test result deviation caused by non-uniform deformation of the chamber edge in the prior art.

[0046] The above-described embodiments are merely preferred embodiments provided to fully illustrate the present invention, and the scope of protection of the present invention is not limited thereto. Equivalent substitutions or modifications made by those skilled in the art based on the present invention are all within the scope of protection of the present invention. The scope of protection of the present invention is defined by the claims.

Claims

1. A pressure testing system for cryogenic liquid cargo storage tanks, characterized in that, include: The base is a circular base plate; The test unit is a circle that matches the shape of the base plate. The test unit is placed on the base plate. The test unit includes, from bottom to top, a secondary insulation layer, a secondary shielding layer, a primary insulation layer, and a primary shielding layer. The secondary insulation layer includes a secondary polyurethane block and a secondary outer plywood and a secondary inner plywood that hold the secondary polyurethane block in place. The secondary shielding layer is provided with a first corrugation that protrudes towards the base plate. A hydraulic chamber is disposed above the test unit, which is clamped between the hydraulic chamber and the base. The hydraulic chamber includes a rigid outer wall and an elastic inner liner. A fixed flange is provided on the outer periphery of the lower end of the rigid outer wall. The fixed flange and the base plate are connected by multiple double-ended screws. The length of the double-ended screws is greater than the original thickness of the test unit. The two ends of the double-ended screws pass through the fixed flange and the base plate respectively and are locked by nuts. The upper end of the rigid outer wall is sealed by a flange cover. The elastic inner liner can extend and retract axially. One end of the elastic inner liner is sealed and welded to the main shielding layer, and the other end is sealed by a sealing plate. The elastic inner liner, the sealing plate, and the main shielding layer together form a sealed pressurized chamber. A pressure-pressuring device that passes through the sealing plate and connects to the pressure chamber.

2. The pressure testing system for cryogenic liquid cargo storage tanks as described in claim 1, characterized in that, The test unit is formed by cutting the cryogenic liquid cargo storage tank.

3. The pressure testing system for cryogenic liquid cargo storage tanks as described in claim 1, characterized in that, The main shielding layer is provided with a first main corrugation that protrudes toward the hydraulic chamber.

4. The pressure testing system for cryogenic liquid cargo storage tanks as described in claim 1, characterized in that, The main shielding layer is provided with a second main corrugation that protrudes toward the base plate.

5. The pressure testing system for cryogenic liquid cargo storage tanks as described in any one of claims 1-4, characterized in that, The secondary shielding layer is further provided with a second corrugation protruding toward the hydraulic chamber. The second corrugation is provided along the extension direction of the first corrugation, and the first corrugation and the second corrugation are connected by a transition section.

6. The pressure testing system for cryogenic liquid cargo storage tanks as described in claim 5, characterized in that, The main shielding layer is provided with a first main corrugation protruding towards the hydraulic chamber and a second main corrugation protruding towards the base plate. The second main corrugation is provided along the extension direction of the first main corrugation, and the first main corrugation and the second main corrugation are connected by a transition section.

7. The pressure testing system for cryogenic liquid cargo storage tanks as described in any one of claims 1-4, characterized in that, The main insulation layer is composed of main plywood.

8. The pressure testing system for cryogenic liquid cargo storage tanks as described in claim 1, characterized in that, The test unit also includes a support wall located on the side close to the base plate, and a resin mortar is provided between the support wall and the secondary insulation layer.

9. The pressure testing system for cryogenic liquid cargo storage tanks as described in claim 1, characterized in that, The elastic inner liner is a metal corrugated pipe.

10. The pressure testing system for cryogenic liquid cargo storage tanks as described in claim 1, characterized in that, At least four double-ended screws are provided, and the double-ended screws are evenly distributed along the circumference of the hydraulic chamber. Supports are connected to the outer sides of the base plate and the flange cover.

11. The pressure testing system for cryogenic liquid cargo storage tanks as described in claim 1, characterized in that, The test unit is coaxially mounted with the base via a positioning structure.

12. The pressure testing system for cryogenic liquid cargo storage tanks as described in claim 1, characterized in that, It also includes a pressure gauge, which is connected to the pressurization chamber.

13. A pressure testing method for a cryogenic liquid cargo storage tank, characterized in that, The pressure testing system for cryogenic liquid cargo storage tanks according to any one of claims 1 to 12 includes the following steps: S10: Cut the cryogenic liquid cargo storage tank to form a test unit, place the test unit on the base, and make the test unit from bottom to top consist of a secondary insulation layer, a secondary shielding layer, a primary insulation layer and a primary shielding layer. S20: Connect the pressure device to the inside of the elastic inner liner, and then place the hydraulic chamber cover on top of the test unit. First, seal and weld the elastic inner liner to the main shielding layer, and then fit the rigid outer wall over the elastic inner liner. At the same time, connect the rigid outer wall to the base plate through a double-headed screw, and keep the distance between the hydraulic chamber and the base at the original thickness of the test unit. S30: Pressurized liquid is injected into the elastic inner liner through a pressurizing device. The test unit is compressed and its thickness decreases, and the elastic inner liner elongates accordingly. S40: The pressure inside the pressurization chamber is detected by a pressure gauge, and the thickness change of the test unit is measured to complete the test of the pressure-bearing capacity of the test unit.

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