Dihedral corner piece for liquefied natural gas storage tank and manufacturing method thereof

Abstract

The invention relates to the technical field of storage tank connecting pieces, and discloses a reverse angle piece for a liquefied natural gas storage tank, the reverse angle piece comprises a reverse angle piece body, the reverse angle piece body is arranged to be a boss section of an arc-shaped bent structure, and transition sections of arc-shaped bent structures are arranged on the two sides of the boss section. By the adoption of the structural design of the integrally-formed reverse corner pieces, the fundamental defects existing in a traditional tailor-welding process are thoroughly overcome, an original split type tailor-welding structure of two 45-degree corner pieces is innovatively improved into an integrated structure of a continuous arc-shaped curved surface, and welding procedures and a series of problems caused by the welding procedures are completely eliminated.

Description

Technical Field

[0001] This invention relates to the field of tank connectors, and more specifically to a countersunk corner fitting for liquefied natural gas storage tanks and a method for manufacturing the same. Background Technology

[0002] Liquefied natural gas (LNG) is the cleanest fossil fuel on Earth and is becoming one of the fastest-growing energy industries globally, driven by the low-carbon energy transition. LNG, formed by compressing and cooling natural gas to -162°C, is typically stored and transported in specialized, insulated tanks. The inner membrane lining of these tanks is generally made of low-temperature brittle materials, such as stainless steel. It expands or contracts with changes in LNG pressure, temperature, and load, and provides a sealing function to prevent leakage. The LNG tank inner membrane includes corrugated plates installed at the bottom and walls of the tank, corner fittings connecting and sealing the bottom and walls, end caps sealing the corrugated plates, and offset caps.

[0003] The corner fitting, as a connector on the inner wall of the storage tank, serves to connect and seal the bottom and the wall. Existing models typically consist of two 45° corner fittings welded together. The first and second corner fittings are cut at a 45° angle on their curved surfaces, and then the two curved surfaces are aligned and welded together to form a complete structure. This production method requires the production of two 45° corner fittings. Traditional processes involve seven steps: forming, cutting, secondary forming, re-cutting, welding, polishing, and shaping. The part has a complex structure, numerous processing steps, and involves welding. Welding the membrane plate of liquefied natural gas storage tanks is a type of special welding, requiring professional technical training and certification for operation. It demands a high level of welding skill, resulting in high welding costs, a high defect rate, and issues such as deformation and uneven weld surfaces after welding. Polishing of the weld and reshaping of the part are necessary, making the entire process cumbersome, complex, and time-consuming. Summary of the Invention

[0004] In order to overcome the above-mentioned defects of the prior art, the present invention provides a reverse corner piece for liquefied natural gas storage tanks and a method for manufacturing the same, so as to solve the problems existing in the background art.

[0005] The present invention provides the following technical solution: a corner bracket for a liquefied natural gas storage tank, comprising a corner bracket body, the corner bracket body being configured as a boss section with an arc-shaped curved structure, and both sides of the boss section being provided with transition sections with an arc-shaped curved structure.

[0006] The cross-sectional profile of the anti-angle piece body is provided with three finite points: Z, X, and C. The distance from finite point Z to the center line L of the anti-angle piece body is a, the distance from finite point X to the center line L of the anti-angle piece body is b, and the distance from finite point C to the center line L of the anti-angle piece body is c. The length ratio of a, b, and c is 4:7:9. The central angle corresponding to the arc surface at the connection between the boss section and the transition section is 70°. The spatial shape of the anti-angle piece body is formed by using the cross-sectional profile of the anti-angle piece body as a guide surface and continuously moving the guide surface along the generatrix M of the anti-angle piece body.

[0007] Preferably, the liquefied natural gas storage tank includes a tank bottom plate and a tank wall plate, with a corrugated section one extending from the end of the tank bottom plate and a corrugated section two extending from the end of the tank wall plate. Multiple anti-angle pieces are evenly arranged between the tank bottom plate and the tank wall plate. The anti-angle pieces are made by integral molding, and a support plate is provided between two adjacent anti-angle pieces.

[0008] Preferably, the boss section is configured as a connecting part, a first anastomosis part, and a second anastomosis part. The connecting part is disposed between the first anastomosis part and the second anastomosis part. The first anastomosis part is welded to the first corrugated section, and the second anastomosis part is welded to the second corrugated section.

[0009] Preferably, the transition section is configured as a connecting part, an overlapping part one, and an overlapping part two. The connecting part is located between the overlapping part one and the overlapping part two. The overlapping part one is welded to the bottom plate of the storage tank, and the overlapping part two is welded to the wall plate of the storage tank.

[0010] Preferably, an installation gap is provided between the tank bottom plate and the tank wall plate, and the connecting part and the connecting part are used to seal the installation gap. The receiving plate is located in the area between two adjacent anti-angle parts and is used to seal the installation gap. The cross-sectional shape of the receiving plate is the same as the cross-sectional shape of the transition section, and both sides of the receiving plate are welded to the transition section.

[0011] The beneficial effects of the first embodiment of this invention are as follows: By adopting an integrated anti-corner component structure design, the fundamental defects of traditional welding processes are completely solved. The original separate 45° corner component welding structure is innovatively improved into an integrated structure with a continuous arc-shaped surface, completely eliminating the welding process and the series of problems it brings. First, it avoids the problem of high defect rate due to insufficient welding technology, significantly improving product qualification rate and consistency. Second, it fundamentally eliminates the quality risks of welding deformation and uneven weld surface, saving subsequent straightening and polishing processes. Third, the integrated arc-shaped surface structure optimizes stress distribution, improves the structural integrity and sealing reliability of the anti-corner component under low-temperature conditions, and effectively reduces the risk of liquefied natural gas leakage. In addition, this design reduces reliance on special welding technologies, lowers the technical requirements and training costs for operators, thereby effectively controlling production costs and providing a safer, more reliable, economical, and efficient key connection component for liquefied natural gas storage tanks.

[0012] Based on the aforementioned anti-angle component for liquefied natural gas storage tanks, a second embodiment of the present invention is proposed.

[0013] Therefore, the present invention provides a method for manufacturing a reverse corner piece, comprising the following steps: S1: Bending and forming; S2: Edge trimming; S3: Cut end face; S4: Pressing boss.

[0014] Preferably, in step S1, a 1.5mm thick stainless steel plate is bent and formed in one go using a press, with a forming pressure of 200 tons and a holding time of 6 seconds, to form a blank with a transition section structure.

[0015] Preferably, in step S2, the blank obtained in S1 is contour-cut using a laser cutting device with a cutting accuracy of ±0.1mm.

[0016] Preferably, in step S3, a CNC milling machine is used to finish the end face of the blank obtained in S2 to ensure that the perpendicularity error of the end face is not greater than 0.05mm.

[0017] Preferably, in step S4, a hydraulic press is used to punch out a boss section at a preset position on the blank obtained in S3. The pressure is 50 tons and the holding time is 6 seconds. After the boss section is punched out, stress-relieving annealing is performed. The annealing temperature is 400℃ and the holding time is 30 minutes. The blank is cooled to below 150℃ in the furnace and then removed from the furnace to obtain the finished anti-corner part body.

[0018] The beneficial effects of the second embodiment of this invention are as follows: Through innovative optimization of the process flow, significant progress has been made in the manufacturing technology of anti-corner parts. The new four-step process flow replaces the traditional seven-step complex process, which not only simplifies the production process but also brings multiple technical and economic benefits and ensures the quality of one-time molding. The use of a high-precision press for one-time molding of the arc-shaped surface structure replaces the original multiple molding and cutting processes, ensuring the consistency of parts and improving material utilization. Eliminating the welding process not only eliminates deformation and defects caused by welding but also avoids the high equipment investment and personnel training costs required for special welding. Finally, by optimizing process parameters and introducing stress-relieving annealing treatment, the dimensional accuracy and mechanical properties of the anti-corner parts are further improved, ensuring long-term reliable operation of the product in extreme low-temperature environments. This manufacturing method has advantages such as simple processes, stable quality, and low cost, perfectly meeting the needs of modern large-scale production and providing an advanced and reliable solution for the liquefied natural gas storage tank manufacturing industry. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the overall structure of the present invention.

[0021] Figure 2 This is a schematic diagram of the mounting gap structure of the present invention.

[0022] Figure 3 This is an exploded view of the overall structure of the present invention.

[0023] Figure 4 This is a cross-sectional view of the tank bottom plate, tank wall plate, and anti-angle component of the present invention.

[0024] Figure 5 This is a schematic diagram of the anti-angle component body structure of the present invention.

[0025] Figure 6 This is a schematic diagram of the anti-angle component body structure of the present invention.

[0026] Figure 7 This is a top view of the anti-angle component body of the present invention.

[0027] Figure 8 This is a side view of the anti-angle component body of the present invention.

[0028] The attached figures are labeled as follows: 1. Tank bottom plate; 11. Corrugated section one; 2. Tank wall plate; 21. Corrugated section two; 3. Angle bracket body; 31. Boss section; 311. Connecting part; 312. Fitting part one; 313. Fitting part two; 32. Transition section; 321. Connecting part; 322. Overlapping part one; 323. Overlapping part two; 4. Support plate; 5. Installation gap. Detailed Implementation

[0029] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0030] Example 1: A corner bracket for a liquefied natural gas storage tank includes a corner bracket body 3. The corner bracket body 3 is configured as a boss section 31 with an arc-shaped curved structure, and arc-shaped curved transition sections 32 are provided on both sides of the boss section 31. The arc-shaped curved boss section 31 and transition sections 32 achieve uniform stress distribution, avoid stress concentration problems at right-angle connections, and significantly improve fatigue resistance and durability under low-temperature conditions.

[0031] The cross-sectional profile of the anti-angle piece body 3 is provided with finite point one Z, finite point two X, and finite point three C. The distance from finite point one Z to the center line L of the anti-angle piece body 3 is a, the distance from finite point two X to the center line L of the anti-angle piece body 3 is b, and the distance from finite point three C to the center line L of the anti-angle piece body 3 is c. The length ratio of a, b, and c is 4:7:9. The central angle corresponding to the arc surface at the connection between the boss section 31 and the transition section 32 is 70°. The spatial shape of the anti-angle piece body 3 is formed by using the cross-sectional profile of the anti-angle piece body 3 as a guide surface and continuously moving the guide surface along the generatrix M of the anti-angle piece body 3. This spatial curved surface modeling based on strict mathematical proportions significantly reduces stress concentration caused by structural abrupt changes. Especially when subjected to alternating loads such as low-temperature shrinkage and internal pressure fluctuations, it can effectively delay the generation and propagation of fatigue cracks, greatly improving the durability and reliability of components under extreme working conditions. The construction method of generating spatial curved surfaces by using the cross-sectional profile as a guide surface and continuously moving along the generatrix M ensures the realization of the one-piece molding process, making the overall structure of the anti-corner component continuous and without weak welds. This not only enhances the sealing performance and avoids potential leakage risks, but also simplifies the manufacturing process and improves the consistency and quality stability of the product.

[0032] The liquefied natural gas (LNG) storage tank includes a tank bottom plate 1 and a tank wall plate 2. The bottom plate 1 has a corrugated section 11 extending from its end, and the tank wall plate 2 has a corrugated section 21 extending from its end. Multiple angled bracket bodies 3 are evenly distributed between the bottom plate 1 and the tank wall plate 2. The angled bracket bodies 3 are integrally formed, and a receiving plate 4 is provided between adjacent angled bracket bodies 3. The integral forming process completely eliminates weld defects in traditional welded structures, improving sealing reliability. The evenly distributed angled bracket bodies 3, in conjunction with the receiving plate 4, enhance the overall structural stability and load-bearing capacity, ensuring effective resistance to stress caused by liquid pressure and temperature changes in low-temperature environments.

[0033] The boss section 31 is configured with a connecting part 311, a first mating part 312, and a second mating part 313. The connecting part 311 is located between the first mating part 312 and the second mating part 313. The first mating part 312 is welded to the first corrugated section 11, and the second mating part 313 is welded to the second corrugated section 21. The segmented design of the boss section 31 allows each part to precisely align with the corresponding corrugated section, ensuring the strength and sealing of the connection and reducing the risk of leakage.

[0034] The transition section 32 is configured with a connecting part 321, an overlapping part one 322, and an overlapping part two 323. The connecting part 321 is located between the overlapping part one 322 and the overlapping part two 323. The overlapping part one 322 is welded to the bottom plate 1 of the storage tank, and the overlapping part two 323 is welded to the wall plate 2 of the storage tank. The segmented design and welded connection of the transition section 32 further enhance the integrity of the corner piece and the tank structure, ensuring structural integrity under temperature changes and pressure fluctuations.

[0035] An installation gap 5 is provided between the tank bottom plate 1 and the tank wall plate 2. The connecting part 311 and the connecting part 321 are used to seal the installation gap 5. The receiving plate 4 is located in the area between two adjacent anti-angle parts 3, and the receiving plate 4 is used to seal the installation gap 5. The cross-sectional shape of the receiving plate 4 is the same as that of the transition section 32. Both sides of the receiving plate 4 are welded to the transition section 32. Through the continuous curved surface structure of the connecting part 311 and the connecting part 321 and the welded connection between the receiving plate 4 and the transition section 32, a continuous and uniform force transmission path is formed, which effectively disperses the stress caused by temperature changes and internal pressure fluctuations and avoids stress concentration. The welded joint between the receiving plate 4 and the transition section 32 is in a low-stress area, which further enhances the fatigue life and sealing reliability of the joint and ensures the integrity and stability of the structure under low-temperature conditions.

[0036] In summary, Example 1, by adopting an integrated corner piece structure design, completely solves the fundamental defects of the traditional welding process. It innovatively improves the original two separate 45° corner piece welding structure into an integrated structure with a continuous arc surface, completely eliminating the welding process and the series of problems it brings.

[0037] Firstly, it avoids the problem of high defect rates caused by insufficient welding technology, significantly improving product qualification rate and consistency. Secondly, it fundamentally eliminates the quality risks of welding deformation and uneven weld surfaces, eliminating the need for subsequent straightening and polishing processes. Thirdly, the one-piece molded arc-shaped surface structure optimizes stress distribution, improves the structural integrity and sealing reliability of the anti-angle component under low-temperature conditions, and effectively reduces the risk of liquefied natural gas leakage. In addition, this design reduces reliance on special welding technologies, lowers the technical requirements and training costs for operators, thereby effectively controlling production costs and providing safer, more reliable, and more cost-effective key connection components for liquefied natural gas storage tanks.

[0038] Example 2 provides a method for manufacturing a reverse corner piece, including the following steps: S1: Bending and forming; S2: Edge trimming; S3: End face trimming; S4: Pressing boss.

[0039] The four-step streamlined process replaces the traditional seven-step complex process, significantly improving production efficiency, reducing production costs, and ensuring consistent product quality.

[0040] In step S1, a 1.5mm thick stainless steel plate is bent and formed in one go using a press. The forming pressure is 200 tons and the holding time is 6 seconds, forming a blank with a transition section 32 structure.

[0041] In step S2, the blank obtained in step S1 is contour-cut using a laser cutting device with a cutting accuracy of ±0.1mm.

[0042] In step S3, a CNC milling machine is used to finish the end face of the blank obtained in step S2 to ensure that the perpendicularity error of the end face is no more than 0.05mm.

[0043] In step S4, a hydraulic press is used to punch out a boss section 31 at a preset position on the blank obtained in S3. The pressure is 50 tons and the holding time is 6 seconds. After the boss section 31 is punched out, stress-relief annealing is performed. The annealing temperature is 400℃ and the holding time is 30 minutes. The blank is cooled to below 150℃ in the furnace and then removed from the furnace to obtain the finished anti-corner part body 3.

[0044] In summary, the manufacturing method provided in Example 2 has achieved significant progress in the manufacturing technology of corner pieces through innovative optimization of the process flow. The new four-step process flow replaces the traditional seven-step complex process, which not only simplifies the production process but also brings multiple technical and economic benefits and ensures the quality of one-time molding.

[0045] The high-precision press is used to form the arc-shaped surface structure in one step, replacing the original multiple forming and cutting processes. This ensures the consistency of the parts and improves material utilization. Eliminating the welding process not only eliminates deformation and defects caused by welding, but also avoids the high equipment investment and personnel training costs required for special welding. Finally, by optimizing process parameters and introducing stress-relieving annealing, the dimensional accuracy and mechanical properties of the anti-angle parts are further improved, ensuring long-term reliable operation of the product in extreme low-temperature environments. This manufacturing method has the advantages of simple process, stable quality and low cost, which perfectly meets the needs of modern large-scale production and provides an advanced and reliable solution for the liquefied natural gas storage tank manufacturing industry.

[0046] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A corner bracket for a liquefied natural gas storage tank, characterized in that, Includes a reverse corner piece body (3), the reverse corner piece body (3) is set as a boss section (31) with an arc-shaped curved structure, and both sides of the boss section (31) are provided with an arc-shaped curved transition section (32). The cross-sectional profile of the anti-angle piece body (3) is provided with finite point one Z, finite point two X, and finite point three C. The distance from finite point one Z to the center line L of the anti-angle piece body (3) is a, the distance from finite point two X to the center line L of the anti-angle piece body (3) is b, and the distance from finite point three C to the center line L of the anti-angle piece body (3) is c. The length ratio of a, b, and c is 4:7:

9. The central angle corresponding to the arc surface at the connection between the boss section (31) and the transition section (32) is 70°. The cross-sectional profile of the anti-angle piece body (3) is used as the guide surface, and the guide surface moves continuously along the generatrix M of the anti-angle piece body (3) to form the spatial shape of the anti-angle piece body (3).

2. The anti-angle fitting for a liquefied natural gas storage tank according to claim 1, characterized in that, The liquefied natural gas storage tank includes a tank bottom plate (1) and a tank wall plate (2). The end of the tank bottom plate (1) is provided with a corrugated section one (11), and the end of the tank wall plate (2) is provided with a corrugated section two (21). Multiple anti-angle body (3) are evenly arranged between the tank bottom plate (1) and the tank wall plate (2). The anti-angle body (3) is made by integral molding. A support plate (4) is provided between two adjacent anti-angle body (3).

3. The anti-angle fitting for a liquefied natural gas storage tank according to claim 2, characterized in that, The boss section (31) is configured as a connecting part (311), a first anastomosis part (312) and a second anastomosis part (313). The connecting part (311) is located between the first anastomosis part (312) and the second anastomosis part (313). The first anastomosis part (312) is welded to the first corrugated section (11), and the second anastomosis part (313) is welded to the second corrugated section (21).

4. A corner bracket for a liquefied natural gas storage tank according to claim 3, characterized in that, The transition section (32) is configured as a connecting part (321), an overlapping part one (322) and an overlapping part two (323). The connecting part (321) is located between the overlapping part one (322) and the overlapping part two (323). The overlapping part one (322) is welded to the bottom plate (1) of the storage tank, and the overlapping part two (323) is welded to the wall plate (2) of the storage tank.

5. A corner bracket for a liquefied natural gas storage tank according to claim 4, characterized in that, An installation gap (5) is provided between the tank bottom plate (1) and the tank wall plate (2). The connecting part (311) and the connecting part (321) are used to seal the installation gap (5). The receiving plate (4) is located in the area between two adjacent anti-angle parts (3) and is used to seal the installation gap (5). The cross-sectional shape of the receiving plate (4) is the same as that of the transition section (32). Both sides of the receiving plate (4) are welded to the transition section (32).

6. A method for manufacturing a corner piece as described in any one of claims 2-5, characterized in that, Includes the following steps: S1: Bending and forming; S2: Edge trimming; S3: Cut end face; S4: Pressing boss.

7. A method for manufacturing a corner piece according to claim 6, characterized in that, In step S1, a 1.5mm thick stainless steel plate is bent and formed in one go using a press. The forming pressure is 200 tons and the holding time is 6 seconds, forming a blank with a transition section (32) structure.

8. A method for manufacturing a corner piece according to claim 7, characterized in that, In step S2, the blank obtained in step S1 is contour-cut using a laser cutting device with a cutting accuracy of ±0.1mm.

9. A method for manufacturing a corner piece according to claim 8, characterized in that, In step S3, a CNC milling machine is used to finish the end face of the blank obtained in step S2 to ensure that the perpendicularity error of the end face is no more than 0.05mm.

10. A method for manufacturing a corner piece according to claim 9, characterized in that, In step S4, a hydraulic press is used to punch out a boss section (31) at a preset position on the blank obtained in S3. The pressure is 50 tons and the holding time is 6 seconds. After the boss section (31) is punched out, stress-relief annealing is performed. The annealing temperature is 400℃ and the holding time is 30 minutes. The blank is cooled to below 150℃ in the furnace and then removed from the furnace to obtain the finished anti-corner body (3).

Images