Design method of locking system for suspended ceiling lifting of LNG (Liquefied Natural Gas) liquid storage tank

Abstract

The invention discloses a design method of a locking system for lifting a suspended ceiling of an LNG (Liquefied Natural Gas) liquid storage tank, and aims to solve the problem that the overall stability and safety of the LNG liquid storage tank are influenced due to inclination of a suspended ceiling pull rod caused by non-uniform stress of a suspender in the suspended ceiling mounting process in the prior art. According to the method, the suspension rod group design is introduced, a traditional single suspension rod is expanded into a plurality of suspension rod groups, and the stability of the suspended ceiling in the installation process is ensured in combination with scientific grouping and stress balance design. Particularly, the locking piece 1 and the locking piece 2 are adopted in the suspended ceiling splicing and suspender connecting process, it is guaranteed that the suspender is kept vertical all the time through accurate fixing and positioning, deviation or inclination of the suspender in the welding process is avoided, and therefore the installation efficiency is improved, and the risk is reduced. In addition, the device is simple in structure, convenient to disassemble and assemble and capable of being repeatedly used, the economic cost is remarkably reduced, and the requirements of a large number of repeated experiments are met.

Description

Technical Field

[0001] The present invention belongs to the technical field of design and construction of large-scale LNG liquid storage tanks, and in particular relates to a design method of a locking system for lifting the ceiling of an LNG liquid storage tank body. Background Art

[0002] As the length of time LNG receiving stations have been in operation continues to increase, the number of LNG storage tanks continues to grow. In recent years, my country's natural gas consumption has increased year by year, accelerating the construction of LNG receiving stations. Currently, most ceiling installations during LNG tank construction utilize aluminum flat panels, circumferential reinforcements, and stainless steel hanger rods. Due to the high demand for aluminum and stainless steel, the total weight of the ceiling structure is high and the thickness is thin. During the welding of the ceiling and the ceiling tie rods, the ceiling is prone to deformation, resulting in uneven stress on the tie rods. Some ceiling tie rods are subjected to excessive stress after welding, while others are not yet welded and are not stressed, causing some stressed ceiling tie rods to tilt, compromising the stability of the entire ceiling and thus affecting the overall safety of the LNG storage tank.

[0003] Therefore, it is necessary to develop a design method for a locking system for lifting the ceiling of an LNG storage tank. During the ceiling installation process, an external force is first applied to the entire ceiling tie rod to keep the entire ceiling tie rod in a vertical state. In this way, the ceiling tie rod can be prevented from tilting when welding with the base plate. At the same time, it must be low in cost, easy to manufacture, and can be disassembled and assembled repeatedly to meet large-scale needs.

[0004] On this basis, the design of boom groups is adopted to expand the single boom into a group. Through scientific grouping and force-balanced design, the problem of uneven force on a single boom is avoided, the boom bearing capacity is made more balanced, and the system stability and processing efficiency are further improved. Summary of the Invention

[0005] The purpose of the present invention is to overcome the defects of the above-mentioned prior art and provide a design method for a locking system for lifting the ceiling of an LNG storage tank.

[0006] In order to solve the above problems, the present invention provides the following technical solutions:

[0007] A design method for a locking system for lifting a ceiling of an LNG storage tank comprises the following steps:

[0008] S1. Design the ceiling system based on the structure and stress requirements of the LNG storage tank, and rationally group the boom groups. Through scientific grouping and force-balancing design, ensure that the ceiling can be evenly stressed during the lifting process;

[0009] S2. Ceiling assembly and boom group installation: Use locking pieces 1 and 2 to connect and secure the booms to the ceiling panels and reinforcement rings, ensuring that the booms always remain vertical and prevent them from shifting or tilting during welding. The use of locking pieces not only ensures the stability of the boom group but also improves the convenience of the ceiling installation process.

[0010] S3. After completing the installation of the hanger group, weld the hangers to the ceiling panels to ensure a firm connection. After welding, check the verticality and force uniformity of the hangers to ensure the stability of the ceiling system. Finally, perform stability testing and safety verification of the entire ceiling system to ensure that the ceiling can withstand the design load and operate stably.

[0011] Furthermore, the locking system includes a locking part 1, a locking part 2 and a hand hoist. The locking part 1 is fixed to the puzzle and the connecting plate, and the locking part 2 is installed on the suspension rod. The locking part 1 and the locking part 2 are connected by the hand hoist. The locking part 1 and the locking part 2 are tightened by the hand hoist to apply a vertical downward external force to the suspension rod to ensure that the suspension rod remains vertical before welding, so that the bottom end of the suspension rod is close to the puzzle, thereby avoiding tilting of the ceiling due to uneven force.

[0012] Furthermore, a groove and a ring are provided inside the locking member 1, the groove is fixed on the puzzle board and the connecting plate, and the ring is connected to the locking member 2 through a hand hoist.

[0013] Furthermore, the locking member 2 includes a circular ring fixing member, a nut, a cross bar and a concave groove. A screw hole is provided on the circular ring fixing member. The circular ring fixing member is placed in the hole at the upper part of the concave groove, and the circular ring fixing member is fixed by passing the cross bar through the screw hole on the circular ring fixing member. The two ends of the cross bar are threaded. Finally, the nuts are installed at both ends of the cross bar and welded to the upper part of the concave groove.

[0014] Furthermore, the boom group is installed in a scientific grouping manner. The boom group is grouped based on the reinforcement ring. Each ring of reinforcement ring is distributed with several booms, which are numbered according to the ring number. Assuming there are k rings of reinforcement rings, they are numbered from R1 to R k , the innermost circle is R1, the outermost circle is R k , the number of booms in each circle n j Determined by the circumference, and as the number of circles increases, the number of booms in each circle increases. For example, if the boom number is D j,1 , D j,2 ,......, Represents the hanger on the jth reinforcement ring.

[0015] Furthermore, the load on the boom group is analyzed circle by circle, and the total load on each reinforcement ring is According to the ratio of its perimeter to the total perimeter, the specific calculation formula is:

[0016]

[0017] Where G is the total design load of the ceiling, ω j is the weight coefficient of the j-th reinforcement ring, and the weight coefficient ω j The determination is based on engineering practice experience, experimental data and simulation calculations. Specifically, the value of the weight coefficient is calculated by the ratio of the circumference of each reinforcing ring to the total circumference, while considering the distribution of the ceiling design load. The following is the calculation of the weight coefficient ω j The process:

[0018]

[0019] Where, L j is the circumference of the jth reinforcement ring L j =2πR j , L total The overall perimeter of the ceiling The calculation method of the weight coefficient is based on multiple LNG engineering cases and combines experimental determination with finite element simulation optimization.

[0020] Furthermore, the average load Q borne by each circle of the boom is j,i The calculation formula is:

[0021]

[0022] Where, is the total design load of the suspended ceiling, n j is the number of booms in the jth circle;

[0023] The actual load Q of each boom j,i Must be less than or equal to the allowable tension F of the boom allow , F allow The calculation formula is:

[0024]

[0025] Where, F break is the breaking tension of the boom, K is the safety factor of the boom;

[0026] At the same time F allow Should meet the following requirements:

[0027] Q1+Q2+F d <F allow

[0028] Q1 is the weight of the hand chain hoist, Q2 is the weight of the locking part 2, F d is the pulling force of the hand hoist;

[0029] Hand chain hoist pulling force F dThe calculation formula is:

[0030]

[0031] Where K1 is the tensile safety factor, α is the angle between the hand chain hoist pulling force and the vertical direction, and Q is the average load on each boom;

[0032] The calculation formula for the pulling force generated by the hand chain hoist on the locking member 1 is:

[0033] F1=F d sinα

[0034] F2=F d cosα

[0035] KF2≤μ(P1+P2)

[0036]

[0037] Where P1 is the horizontal reaction force at the connecting plate, P2 is the horizontal reaction force at the joint plate, μ is the friction coefficient between the locking piece 1 and the connecting plate and the joint plate, and F1 is the pulling force F of the hand hoist. d The horizontal component of force, F2 is the hand hoist pulling force F d The vertical component of force, K is the tensile safety factor, a1 is the vertical distance from F1 to P1, a2 is the vertical distance from P1 to P2, α is the hand hoist pulling force F d Angle with the vertical direction;

[0038] The calculation formula for the strength verification of the upper edge of the hook hole of the locking piece 1 is:

[0039]

[0040] Where σ is the normal stress at the tensile edge of the AC section, τ is the shear stress at the AC section, and [f] is the design value of the tensile strength of the steel, which is 140 N / mm for No. 3 steel. 2 .

[0041] Furthermore, the forces acting on the multiple rings of the hanger rods are progressively analyzed. The force and moment balance of the hanger rod group is a key issue in the design. The inner ring hangers are close to the center of mass of the ceiling and bear a large moment, while the outer ring hangers are numerous and share the total load. The moments of the inner and outer ring hangers must meet the balance condition:

[0042]

[0043] Where, d j,i is the horizontal distance from the i-th hanger rod in the j-th circle to the centroid of the ceiling, and τ is the load of the i-th hanger rod in the j-th circle.

[0044] Furthermore, the dynamic stability of the boom group is determined by the correction coefficient δ j.i After adjustment, the dynamic correction force is:

[0045] Q j,i =Q j,i,static ·(1+δ j.i )

[0046] Where Q j,i,static is the static calculation load, δ j.i It is a dynamic correction coefficient, which is determined by wind load and vibration factors.

[0047] Furthermore, the stiffness calculation formula of each of the suspension rods is:

[0048]

[0049] Where E is the elastic modulus of the suspender, A is the cross-sectional area of ​​the suspender, and L is j,i is the length of the boom;

[0050] Each boom needs to meet the bending stability conditions:

[0051]

[0052] Where N j,i is the axial force of the j-th ring of the hanger rod, E is the elastic modulus of the hanger rod material, I is the section moment of inertia of the hanger rod, and K is the rod length coefficient;

[0053] The connection strength between the boom and the reinforcement ring must meet the following conditions:

[0054]

[0055] Where A conn,j is the effective area of ​​the connection between the jth ring of suspenders and the reinforcement ring, σ conn,j is the actual stress at the connection between the j-th circle hanger and the reinforcement ring.

[0056] The beneficial effects of the present invention are:

[0057] To improve the stability and processing efficiency of the suspended ceiling system, the present invention adopts a hanger group design, expanding the traditional single hanger into multiple hanger groups. Through scientific grouping and force-balancing design, the overall performance of the suspended ceiling system is further optimized. During the suspended ceiling installation process, the long length, thin thickness, and large number of hangers result in a large workload for assembling the suspended ceiling. To solve this problem, the present invention specially designs a locking piece, which firmly connects the suspended ceiling to the hanger, effectively simplifying the assembly and installation process of the suspended ceiling. While ensuring the stability of the connection between the suspended ceiling and the hanger, the locking piece greatly improves the convenience and work efficiency of installation, avoids displacement or loosening of the suspended ceiling during installation, and thus improves the overall stability and safety of the system.

[0058] The present invention solves the problem that during the installation of the existing large-scale LNG storage tank ceiling, the uneven force on the ceiling tie rod during the welding process of the ceiling and the ceiling tie rod will cause the ceiling tie rod to tilt, causing the stability of the entire ceiling to be affected, thereby affecting the overall safety of the LNG storage tank. Different parts are fixed and positioned to each other in a variety of ways, and the overall stability and reliability of the device are high. The device of the present invention is simple to manufacture, easy to assemble and disassemble, and can be reused to reduce economic costs and meet the needs of a large number of repetitive tests. By adopting a hanger group design, a single hanger is expanded into multiple hanger groups. Combined with scientific grouping and force balance design, the stability, processing efficiency and overall performance of the ceiling system are further improved.

[0059] The present invention effectively solves the following problems in the prior art by optimizing the design of the boom group, introducing a weight coefficient calculation method, and applying a locking system:

[0060] 1. Uneven force: Through scientific grouping and weight coefficient calculation, the force on the boom is made more uniform.

[0061] 2. Imperfect calculation method: Complete force calculation, dynamic correction and strength verification methods have been added to ensure calculation accuracy and versatility.

[0062] 3. Unstable structure: By using locking parts 1 and 2, the verticality of the suspension rod is improved, the installation error is reduced, and the stability of the ceiling is ensured. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] The following text will describe in detail specific embodiments of the present invention in an illustrative and non-limiting manner with reference to the accompanying drawings. The same reference numerals in the accompanying drawings indicate the same or similar components or parts. It should be understood by those skilled in the art that these drawings are not necessarily drawn to scale. In the accompanying drawings:

[0064] Figure 1 A flowchart of the locking system design method of the present invention;

[0065] Figure 2 A schematic structural diagram of the locking system design method of the present invention;

[0066] Figure 3 This is a schematic diagram of the stability of the pull rod of the present invention;

[0067] Figure 4 A schematic diagram of the force on the ceiling of the locking system design method of the present invention;

[0068] Figure 5 Schematic diagram of the pulling force of the hand chain hoist on the locking member 1;

[0069] Figure 6 It is a cross-sectional view of the locking member 1. DETAILED DESCRIPTION

[0070] To make the purpose, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below in conjunction with the specific embodiments of this application and the corresponding drawings. Obviously, the embodiments described are only part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application. The content of the present invention is illustrated below with reference to examples.

[0071] Example

[0072] See also Figures 1-6 A design method for a locking system for lifting the ceiling of an LNG storage tank includes the following steps:

[0073] S1. Design the ceiling system based on the structure and stress requirements of the LNG storage tank, and rationally group the boom groups. Through scientific grouping and force-balancing design, ensure that the ceiling can be evenly stressed during the lifting process;

[0074] S2. Ceiling assembly and boom group installation: Use locking pieces 1 and 2 to connect and secure the booms to the ceiling panels and reinforcement rings, ensuring that the booms always remain vertical and prevent them from shifting or tilting during welding. The use of locking pieces not only ensures the stability of the boom group but also improves the convenience of the ceiling installation process.

[0075] S3. After completing the installation of the hanger group, weld the hangers to the ceiling panels to ensure a firm connection. After welding, check the verticality and force uniformity of the hangers to ensure the stability of the ceiling system. Finally, perform stability testing and safety verification of the entire ceiling system to ensure that the ceiling can withstand the design load and operate stably.

[0076] Furthermore, the locking system includes a locking part 1, a locking part 2 and a hand hoist. The locking part 1 is fixed to the puzzle and the connecting plate, and the locking part 2 is installed on the suspension rod. The locking part 1 and the locking part 2 are connected by the hand hoist. The locking part 1 and the locking part 2 are tightened by the hand hoist to apply a vertical downward external force to the suspension rod to ensure that the suspension rod remains vertical before welding, so that the bottom end of the suspension rod is close to the puzzle, thereby avoiding tilting of the ceiling due to uneven force.

[0077] Furthermore, a groove and a ring are provided inside the locking piece 1, the groove is fixed on the puzzle board and the connecting plate, and the ring is connected to the locking piece 2 through a hand hoist.

[0078] Furthermore, the locking member 2 includes a circular ring fixing member, a nut, a cross bar and a concave groove. A screw hole is provided on the circular ring fixing member. The circular ring fixing member is placed in the hole at the upper part of the concave groove, and the circular ring fixing member is fixed by passing the cross bar through the screw hole on the circular ring fixing member. The two ends of the cross bar are threaded. Finally, the nuts are installed at both ends of the cross bar and welded to the upper part of the concave groove.

[0079] Furthermore, the boom group is installed in a scientific grouping method. The boom group is grouped based on the reinforcement ring. Each ring of reinforcement ring is distributed with several booms, which are numbered according to the ring number. Assuming there are k rings of reinforcement rings, they are numbered from R1 to R k , the innermost circle is R1, the outermost circle is R k , the number of booms in each circle n j Determined by the circumference, and as the number of circles increases, the number of booms in each circle increases. For example, if the boom number is D j,1 , D j,2 ,......, Represents the hanger on the jth reinforcement ring.

[0080] Furthermore, the load on the boom group is analyzed circle by circle, and the total load on each reinforcement ring is According to the ratio of its perimeter to the total perimeter, the specific calculation formula is:

[0081]

[0082] Where G is the total design load of the ceiling, ω j is the weight coefficient of the j-th reinforcement ring, and the weight coefficient ω j The determination is based on engineering practice experience, experimental data and simulation calculations. Specifically, the value of the weight coefficient is calculated by the ratio of the circumference of each reinforcing ring to the total circumference, while considering the distribution of the ceiling design load. The following is the calculation of the weight coefficient ω j The process:

[0083]

[0084] Where, L jis the circumference of the jth reinforcement ring L j =2πR j , L total The overall perimeter of the ceiling The weight coefficient calculation method is based on multiple LNG project cases and combines experimental measurements with finite element simulation optimization. In practical applications, this calculation method can ensure that suspended ceilings of different specifications have reasonable force distribution, thereby improving versatility.

[0085] Furthermore, the average load Q borne by each circle of the boom is j,i The calculation formula is:

[0086]

[0087] Where, is the total design load of the suspended ceiling, n j is the number of booms in the jth circle;

[0088] The actual load Q of each boom j,i Must be less than or equal to the allowable tension F of the boom allow , F allow The calculation formula is:

[0089]

[0090] Where, F break is the breaking tension of the boom, K is the safety factor of the boom;

[0091] At the same time F allow Should meet the following requirements:

[0092] Q1+Q2+F d <F allow

[0093] Q1 is the weight of the hand chain hoist, Q2 is the weight of the locking part 2, F d is the pulling force of the hand hoist;

[0094] Hand chain hoist pulling force F d The calculation formula is:

[0095]

[0096] Where K1 is the tensile safety factor, α is the angle between the hand chain hoist pulling force and the vertical direction, and Q is the average load on each boom;

[0097] The calculation formula for the pulling force generated by the hand chain hoist on the locking member 1 is:

[0098] F1=F d sinα

[0099] F2=Fd cosα

[0100] KF2≤μ(P1+P2)

[0101]

[0102] Where P1 is the horizontal reaction force at the connecting plate, P2 is the horizontal reaction force at the joint plate, μ is the friction coefficient between the locking piece 1 and the connecting plate and the joint plate, and F1 is the pulling force F of the hand hoist. d The horizontal component of force, F2 is the hand hoist pulling force F d The vertical component of force, K is the tensile safety factor, a1 is the vertical distance from F1 to P1, a2 is the vertical distance from P1 to P2, α is the hand hoist pulling force F d Angle with the vertical direction;

[0103] The calculation formula for the strength verification of the upper edge of the hook hole of the locking piece 1 is:

[0104]

[0105] Where σ is the normal stress at the tensile edge of the AC section, τ is the shear stress at the AC section, and [f] is the design value of the tensile strength of the steel, which is 140 N / mm for No. 3 steel. 2 .

[0106] Furthermore, a progressive analysis of the forces acting on the multiple rings of hangers was conducted. The force and moment balance of the hanger group is a key issue in the design. The inner ring hangers are close to the center of mass of the ceiling and bear a large moment, while the outer ring hangers are numerous and share the total load. The moments of the inner and outer ring hangers must meet the following equilibrium conditions:

[0107]

[0108] Where, d j,i is the horizontal distance from the i-th hanger rod in the j-th circle to the centroid of the ceiling, and τ is the load of the i-th hanger rod in the j-th circle.

[0109] Furthermore, the dynamic stability of the boom group is determined by the correction factor δ j.i After adjustment, the dynamic correction force is:

[0110] Q j,i =Q j,i,static ·(1+δ j.i )

[0111] Where Q j,i,static is the static calculation load, δ j.i It is a dynamic correction coefficient, which is determined by wind load and vibration factors.

[0112] Furthermore, the stiffness calculation formula of each boom is:

[0113]

[0114] Where E is the elastic modulus of the suspender, A is the cross-sectional area of ​​the suspender, and L is j,i is the length of the boom;

[0115] Each boom needs to meet the bending stability conditions:

[0116]

[0117] Where N j,i is the axial force of the j-th ring of the hanger rod, E is the elastic modulus of the hanger rod material, I is the section moment of inertia of the hanger rod, and K is the rod length coefficient;

[0118] The connection strength between the boom and the reinforcement ring must meet the following conditions:

[0119]

[0120] Where A conn,j is the effective area of ​​the connection between the jth ring of suspenders and the reinforcement ring, σ conn,j is the actual stress at the connection between the j-th circle hanger and the reinforcement ring.

[0121] In this embodiment, the total design load G0 of the suspended ceiling system is 1000 kN. This load includes the weight of the suspended ceiling, additional loads during installation (such as wind load and vibration load), and the weight of the suspended ceiling support structure. Based on the various load conditions that may occur during actual construction, a conservative design approach was adopted to ensure safe operation of the system under all operating conditions.

[0122] In this embodiment, 14 reinforcing rings are used, with the radius of each ring increasing sequentially according to design requirements. The number of booms is determined by the circumference of each reinforcing ring and the load requirements. Specific parameters are 2100mm, 6600mm, 11100mm, 15600mm, 20100mm, 24500mm, 27500mm, 30500mm, 33500mm, 36500mm, 39500mm, 41000mm, 43800mm, and 44985mm. The radius of the reinforcing rings increases gradually to ensure proper load distribution. The number of booms is determined by the circumference of each reinforcing ring, and increases accordingly with the outer ring radius. The number of hanger rods in each circle is 6, 24, 48, 48, 144, 144, 144, 144, 144, 144, 144, 144, 144, and 144, respectively. This distribution effectively ensures that when the outer circle is subjected to greater forces, the load can be distributed by increasing the number of hangers. Based on design requirements and the spatial dimensions of the ceiling system, the lengths of the hanger rods in each circle are 15255mm, 15037mm, 14669mm, 13995mm, 13084mm, 11959mm, 11053mm, 10032mm, 8890mm, 7623mm, 6468mm, 5475mm, 3978mm, and 2962mm, respectively. The above-mentioned suspenders are made of S30403 stainless steel, with an elastic modulus of 1.93×105mPa, a yield strength of 205mPa, and a density of 8000kg / m 3 The material performance meets the requirements of high strength, high corrosion resistance and good welding performance, and is suitable for use in the ceiling system of LNG storage tanks. The 1st to 13th rings of hangers are made of flat steel with a cross-sectional size of 50×8mm and a cross-sectional area of ​​400mm 2 The outermost circle of booms uses angle steel with a cross-sectional size of 90×90×8mm and a cross-sectional area of ​​1440mm 2 .

[0123] When prefabricating the hanger rod, allow at least 100mm of excess length. The hanger rod and its upper connecting plate are welded, while the lower connecting plate is welded during the hanger rod installation. For the ceiling tie rod, weld the central connecting plate before installation. After the ceiling panels are laid and welded in the area, begin installing the ceiling tie rods in that area. Once the ceiling panels and reinforcement rings are installed and welded, connect the tie rods to the ceiling reinforcement rings, and finally, spot weld all bolts and nuts.

[0124] The overall radius of the ceiling is 44,900mm, and the aluminum sheet is 5mm thick. Based on the aluminum sheet size and orientation specified in the drawings, the ceiling panels were laid out from the center outward according to the layout. The minimum overlap required by the drawings was maintained during installation, with all lap welds having an overlap of 30mm and a minimum of 25mm. The welding process was carried out from the outside toward the center. To effectively control deformation, a segmented back-welding method (preferably 1m in segment length) was used to minimize deformation. After the aluminum ceiling was welded, any deformed ceiling rods were cut and adjusted based on the actual deformation to ensure uniform stress on the rods.

[0125] The locking member 1 is 300mm long, 150mm wide, and 18mm thick. Made of stainless steel, the inner groove is 210mm long and 55mm wide. The outer semicircle is tilted upward at 60°, with an outer diameter of 50mm and an inner diameter of 30mm. After the reinforcement ring is installed, the connecting plate is welded to it. The connecting plate has two screw holes, and the puzzle pieces have two corresponding screw holes. The connecting plate and puzzle pieces are fixed together with bolts.

[0126] Locking piece 2 is 100mm long, 70mm wide, 40mm high, and 8mm thick. A 50mm long and 12mm wide hole is cut in the upper portion of the groove. The annular fixing piece is welded together from a circular arc with a radius of 70mm, a central angle of 30°, and a width of 40mm, and a ring with an outer diameter of 80mm and an inner diameter of 40mm. A circular hole is drilled at an appropriate position in the arc. The annular fixing piece is placed in the hole in the upper portion of the groove. A crossbar is used to secure the annular fixing piece through the circular hole in the crossbar. The crossbar is threaded at both ends. Nuts are installed at both ends of the crossbar and finally welded to the upper portion of the groove.

[0127] Install locking piece 2 on the ceiling tie rods, connect locking piece 1 and locking piece 2 with a hand chain hoist, and use the hand chain hoist to preload the tie rods to maintain a vertical position before welding, with the lower end of the tie rods pressed against the panel. Finally, weld the tie rods and panel together. During the welding process of the tie rod group, locking pieces 1 and 2 precisely secure the tie rods, ensuring that each tie rod remains vertical and preventing uneven force, deformation, or deviation. This ensures that the tie rods can stably carry the designed load throughout the ceiling system and prevents problems such as uneven force or tie rod tilting caused by welding errors during the welding process.

[0128] At the same time, the following force analysis formula for the boom group is applied to distribute the load of each reinforcement ring to achieve uniform force on the boom system and avoid uneven force caused by the boom being non-vertical or offset.

[0129] Load per reinforcing ring According to the weight coefficient ω of the circle j To make an allocation:

[0130]

[0131] in:

[0132]

[0133] Weight coefficient ω of each circle j are used to distribute the total load according to the circumference, and through these formulas, ensure that the outer ring hanger group bears more load, while the inner ring hanger group bears less load.

[0134] The average load Q of each boom circle is obtained by calculation j,i :

[0135]

[0136] The maximum load of each ring of booms is 2.1kN, and it is ensured that the load of each boom is within the design allowable range.

[0137] The moment balance of the boom system ensures that the force on the boom group is even and avoids uneven moments. The moment balance formula is:

[0138]

[0139] Where, d j,i represents the horizontal distance from the i-th suspension rod in the j-th circle to the center of mass of the ceiling. This formula ensures that the ceiling will not tilt or be unevenly stressed during installation.

[0140] During implementation, a boom group design was adopted, expanding a single boom into multiple boom groups. Through scientific grouping and force-balanced design, the ceiling was evenly stressed during hoisting and installation, preventing deformation or tilting of the ceiling due to excessive localized stress. The connection between the ceiling panels and the boom group was precisely secured using locking members 1 and 2, ensuring the booms remained vertical at all times and preventing deviation or misalignment during welding. The use of locking members not only improved ceiling installation efficiency and reduced installation time, but also effectively avoided errors during the ceiling assembly process, ensuring the overall stability of the ceiling system.

[0141] During the welding process, locking components ensured a secure connection between the hangers and the ceiling panels. After welding, the hangers were verified for verticality and uniformity of force, ensuring that each hanger could evenly carry the designed load. Ultimately, after stability and safety verification, the ceiling system demonstrated excellent stability, capable of withstanding the various dynamic loads of long-term operation.

[0142] This example fully demonstrates the effectiveness and reliability of the method of the present invention. By optimizing the design of the ceiling system, simplifying the installation process, and improving installation accuracy and stability, it provides an efficient, safe, and economical solution for the installation of the LNG storage tank ceiling system.

[0143] The above description of the design examples is intended to facilitate understanding and application of the present invention by those skilled in the art. It will be apparent to those skilled in the art that various modifications to these designs can be readily made and the general principles described herein can be applied to other examples without requiring any inventive effort. Therefore, the present invention is not limited to the examples presented herein; improvements and modifications made by those skilled in the art based on the present disclosure are intended to fall within the scope of protection of the present invention.

Claims

1. A design method for a locking system for lifting the ceiling of an LNG tank, characterized in that: The following steps are involved: S1. Design the ceiling system based on the structure and stress requirements of the LNG storage tank, and rationally group the boom groups. Through scientific grouping and force-balancing design, ensure that the ceiling can be evenly stressed during the lifting process; S2. Ceiling assembly and boom group installation: Use locking pieces 1 and 2 to connect and secure the booms to the ceiling panels and reinforcement rings, ensuring that the booms always remain vertical and prevent them from shifting or tilting during welding. The use of locking pieces not only ensures the stability of the boom group but also improves the convenience of the ceiling installation process. S3. After completing the installation of the hanger group, weld the hangers to the ceiling panels to ensure a firm connection. After welding, check the verticality and force uniformity of the hangers to ensure the stability of the ceiling system. Finally, perform stability testing and safety verification of the entire ceiling system to ensure that the ceiling can withstand the design load and operate stably.

2. The design method of a locking system for lifting the ceiling of an LNG tank according to claim 1 is characterized in that: The locking system includes a locking part 1, a locking part 2 and a hand hoist. The locking part 1 is fixed to the puzzle and the connecting plate, and the locking part 2 is installed on the suspension rod. The locking part 1 and the locking part 2 are connected by the hand hoist. The locking part 1 and the locking part 2 are tightened by the hand hoist to apply a vertical downward external force to the suspension rod to ensure that the suspension rod remains vertical before welding, so that the bottom end of the suspension rod is close to the puzzle, avoiding the ceiling from tilting due to uneven force.

3. The design method of a locking system for lifting the ceiling of an LNG tank according to claim 2 is characterized in that: The locking piece 1 is provided with a groove and a ring inside, the groove is fixed on the puzzle board and the connecting plate, and the ring is connected to the locking piece 2 through a hand chain hoist.

4. The design method of a locking system for lifting the ceiling of an LNG tank according to claim 2 is characterized in that: The locking member 2 includes a circular ring fixing member, a nut, a cross bar and a concave groove. A screw hole is provided on the circular ring fixing member. The circular ring fixing member is placed in the hole at the upper part of the concave groove, and the circular ring fixing member is fixed by passing the cross bar through the screw hole on the circular ring fixing member. The two ends of the cross bar are threaded. Finally, the nuts are installed at both ends of the cross bar and welded to the upper part of the concave groove.

5. The design method of a locking system for lifting the ceiling of an LNG tank according to claim 1 is characterized in that: The boom group is installed in a scientific grouping manner. The boom group is grouped based on the reinforcement ring. Each circle of reinforcement rings is distributed with several booms, which are numbered according to the ring number. Assuming there are k circles of reinforcement rings, they are numbered from R1 to R k , the innermost circle is R1, the outermost circle is R k , the number of booms in each circle n j Determined by the circumference, and as the number of circles increases, the number of booms in each circle increases. For example, if the boom number is D j,1 , Represents the hanger on the jth reinforcement ring.

6. The design method of a locking system for lifting the ceiling of an LNG tank according to claim 5 is characterized in that: The load of the boom group is analyzed circle by circle, and the total load borne by each reinforcement ring is According to the ratio of its perimeter to the total perimeter, the specific calculation formula is: Where G is the total design load of the ceiling, ω j is the weight coefficient of the j-th reinforcement ring, and the weight coefficient ω j The determination is based on engineering practice experience, experimental data and simulation calculations. Specifically, the value of the weight coefficient is calculated by the ratio of the circumference of each reinforcing ring to the total circumference, while considering the distribution of the ceiling design load. The following is the calculation of the weight coefficient ω j The process: Where, L j is the circumference of the jth reinforcement ring L j =2πR j , L total The overall perimeter of the ceiling The calculation method of the weight coefficient is based on multiple LNG engineering cases and combines experimental determination with finite element simulation optimization.

7. The design method of a locking system for lifting the ceiling of an LNG tank according to claim 6, characterized in that: The average load Q borne by each circle of the boom j,i The calculation formula is: Where, is the total design load of the suspended ceiling, n j is the number of booms in the jth circle; The actual load Q of each boom j,i Must be less than or equal to the allowable tension F of the boom allow , F allow The calculation formula is: Where, F break is the breaking tension of the boom, K is the safety factor of the boom; At the same time F allow Should meet the following requirements: Q1+Q2+F d <F allow Q1 is the weight of the hand chain hoist, Q2 is the weight of the locking part 2, F d is the pulling force of the hand hoist; Hand chain hoist pulling force F d The calculation formula is: Where K1 is the tensile safety factor, α is the angle between the hand chain hoist pulling force and the vertical direction, and Q is the average load on each boom; The calculation formula for the pulling force generated by the hand chain hoist on the locking member 1 is: F1=F d sinα F2=F d cosα KF2≤μ(P1+P2) Where P1 is the horizontal reaction force at the connecting plate, P2 is the horizontal reaction force at the joint plate, μ is the friction coefficient between the locking piece 1 and the connecting plate and the joint plate, and F1 is the pulling force F of the hand hoist. d The horizontal component of force, F2 is the hand hoist pulling force F d The vertical component of force, K is the tensile safety factor, a1 is the vertical distance from F1 to P1, a2 is the vertical distance from P1 to P2, α is the hand hoist pulling force F d Angle with the vertical direction; The calculation formula for the strength verification of the upper edge of the hook hole of the locking piece 1 is: Where σ is the normal stress at the tensile edge of the AC section, τ is the shear stress at the AC section, and [f] is the design value of the tensile strength of the steel, which is 140 N / mm for No. 3 steel. 2 .

8. The design method of a locking system for lifting the ceiling of an LNG tank according to claim 5 is characterized in that: The forces acting on the multiple rings of the hanger rods are progressively analyzed. The force and moment balance of the hanger rod group is a key issue in the design. The inner ring hangers are close to the center of mass of the ceiling and bear a large moment, while the outer ring hangers are numerous and share the total load. The moments of the inner and outer ring hangers must meet the balance condition: Where, d j,i is the horizontal distance from the i-th hanger rod in the j-th circle to the centroid of the ceiling, and τ is the load of the i-th hanger rod in the j-th circle.

9. The design method of a locking system for lifting the ceiling of an LNG tank according to claim 5, characterized in that: The dynamic stability of the boom group is determined by the correction factor δ j.i After adjustment, the dynamic correction force is: Q j,i =Q j,i,static ·(1+δ j.i ) Where Q j,i,static is the static calculation load, δ j.i It is a dynamic correction coefficient, which is determined by wind load and vibration factors.

10. The design method of a locking system for lifting the ceiling of an LNG tank according to claim 5, characterized in that: The stiffness calculation formula of each of the suspension rods is: Where E is the elastic modulus of the suspender, A is the cross-sectional area of ​​the suspender, and L is j,i is the length of the boom; Each boom needs to meet the bending stability conditions: Where N j,i is the axial force of the j-th ring of the hanger rod, E is the elastic modulus of the hanger rod material, I is the section moment of inertia of the hanger rod, and K is the rod length coefficient; The connection strength between the boom and the reinforcement ring must meet the following conditions: Where A conn,j is the effective area of ​​the connection between the jth ring of suspenders and the reinforcement ring, σ conn,j is the actual stress at the connection between the j-th circle hanger and the reinforcement ring.

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