A manufacturing method of LNG ship transportation C type double body storage tank

Abstract

The application discloses a manufacturing method of a C-shaped double-body storage tank for LNG ship transportation, which comprises the following steps: firstly, the C-shaped double-body storage tank is divided into two single-body tanks and a bulkhead plate; then, the single-body tank is sequentially divided into a tank body part and a head part; the tank body part is composed of multiple annular cylinder segments; a track and a roller structure are arranged on a platform; the annular cylinder segments to be welded are aligned by the movement of the roller structure on the track; the annular cylinder segments are driven to rotate around the shaft by the roller structure; the assembly and welding of the tank body part are carried out; and the welding time is greatly reduced. In addition, the head part is prepared by taking the annular cylinder segment as a jig, the rotation of the annular cylinder segment is driven by the roller structure, the rotation of the head part is realized, the welding and fixation of the head part and the tank body part are quickly completed, the assembly and welding of the hemispherical head part are designed by taking the annular cylinder segment adjacent to the hemispherical head part as a jig, and the problems that the welding shrinkage of the head plate is difficult to control due to the large number of head plates and the butt joint of the hemispherical head part and the tank body is affected can be solved.

Description

Technical Field

[0001] This invention relates to the field of shipbuilding technology, and in particular to a method for manufacturing a C-type catamaran storage tank for LNG shipping. Background Technology

[0002] Natural gas is a more efficient and cleaner energy source, and its share in the world's primary energy mix will exceed 25%, potentially surpassing oil to become the world's primary energy source by 2040. The application of cryogenic liquefaction technology can transform natural gas into a liquid state, significantly reducing its volume, which is highly advantageous for long-distance maritime transport. Currently, the majority of global LNG (liquefied natural gas) transportation is conducted by sea using LNG carriers, accounting for over 80% of all transport.

[0003] To improve transportation efficiency, ensure a better fit between LNG storage tanks and ship cargo holds, and maximize cargo capacity utilization, large LNG carriers typically use C-type catamaran tanks. C-type catamaran tanks differ significantly from C-type monohull tanks in structural layout and construction technology. Besides fully considering factors such as strength, sway loads, wave loads, and acceleration, the feasibility, convenience, and construction quality of the construction process are extremely important for the tank structure.

[0004] In the prior art, patent CN 110356512 B discloses a liquefied natural gas shipborne catamaran storage tank and its manufacturing method. After the shell plates are assembled and welded, two first cylindrical sections are welded to form an ∞-shaped structure. Then, a bulkhead is inserted between the two first cylindrical sections and welded to fix it. Next, two left end caps are respectively hoisted onto both sides of the bulkhead and stacked on top of the first cylindrical sections for welding and fixing, thereby assembling and forming tank section I. Two second cylindrical sections are welded to form an ∞-shaped structure. Then, a bulkhead is inserted between the two second cylindrical sections and welded to fix it. Finally, two third cylindrical sections are respectively hoisted onto the bulkhead. The first two sections are welded and fixed on top of the second section, and then the two fourth sections are respectively installed on both sides of the bulkhead and stacked on top of the third section, and welded and fixed, thus assembling tank section II. The two fifth sections are welded to form an ∞-shaped structure, and then the bulkhead is inserted between the five sections on both sides and welded and fixed. Then the two right end caps are respectively hoisted on both sides of the bulkhead and stacked on top of the fifth sections and welded and fixed, thus assembling tank section III. Finally, tank sections I, II, and III are welded and fixed in sequence to form a double-body storage tank. The above manufacturing method can be carried out in a limited space using existing tools and equipment by manufacturing in reasonable segments and sections. However, the above method divides the two storage tanks into two wholes, first welding to form an ∞-shaped structure and then welding them in sequence. Due to the huge volume of the storage tank, when manufacturing a double-body storage tank in the above way, the position of the sections to be welded is fixed, and workers need to move up and down to weld the parts of the storage tank to be welded. The welding process is relatively complex, the utilization rate of automated equipment is low, and the welding time is long.

[0005] In view of this, it is necessary to design a manufacturing method for a C-type catamaran storage tank for LNG shipping in order to solve the above problems. Summary of the Invention

[0006] The purpose of this invention is to provide a method for manufacturing LNG shipping C-type twin tanks that first manufactures individual C-type tanks and then assembles them as a whole, thereby solving the problems of C-type twin tanks being inconvenient to weld, having low utilization of automated equipment, and being time-consuming to manufacture.

[0007] To achieve the above-mentioned objectives, this invention provides a method for manufacturing a C-type catamaran storage tank for LNG shipping, comprising the following steps: S1. Set up a track and a roller structure that can move along the track on the platform used for tank assembly, and press the cylindrical plate and end plate according to the design dimensions. S2. Assemble and weld multiple cylindrical plates into an annular cylindrical section; using the annular cylindrical section as a frame, install multiple end plates on the annular cylindrical section to form an end cap; S3. Place the two annular sections coaxially on the two roller structures respectively, and move the roller structures along the track until the two annular sections are circumferentially aligned. Then, perform preliminary fixing on the two annular sections. Next, use the roller structures to drive the two annular sections to rotate synchronously around their axis and perform circumferential welding on the two annular sections. S4. According to the processing operation in step S3, multiple annular cylindrical sections are assembled and welded to form the cylindrical tank body of the storage tank; at the same time, the annular cylindrical section of the sealing head is placed on the roller structure, and according to the processing operation in step S3, the two sealing heads are installed at both ends of the tank body to form the first single tank. S5. Assemble the second single-unit tank according to steps S2 to S4; S6. Cut openings on the two individual tanks respectively, install the bulkhead on the opening of one of the individual tanks, and then align and weld the openings of the two individual tanks to obtain the C-type twin tank.

[0008] As a further improvement of the present invention, in step S1, the end cap plate includes an equatorial plate, a temperate plate, and a polar plate.

[0009] As a further improvement of the present invention, in step S1, the track includes a transverse track and a longitudinal track, and the roller structure is set on the track by a slider, so that the roller structure can move along the transverse track or the longitudinal track.

[0010] As a further improvement of the present invention, in step S1, the cylindrical plate includes a first arc plate made of low-temperature resistant alloy steel and a second arc plate made of ordinary carbon steel for installation at the corresponding opening position.

[0011] As a further improvement of the present invention, in step S3, the welding process is to perform spot welding, root pass welding and submerged arc welding on the two annular cylinder sections in sequence.

[0012] As a further improvement of the present invention, no root pass welding is performed between the second arc plates of the two annular cylindrical sections.

[0013] As a further improvement of the present invention, in step S3, the preliminary fixing process involves using several fasteners to fix the two annular sections.

[0014] As a further improvement of the present invention, in step S6, the specific operation of aligning the openings of the two individual tanks is as follows: keep the individual tank without the partition plate stationary, and move the individual tank with the partition plate installed until the openings of the two individual tanks are aligned.

[0015] The beneficial effects of this invention are: 1. This invention employs a process of first constructing individual tanks and then assembling the entire structure, solving the problem that non-cylindrical C-type double-walled storage tanks cannot rotate circumferentially and are inconvenient to use automated welding equipment. By driving the annular sections to rotate via a roller structure, welding each annular section and the annular section to the end cap is performed sequentially along the axial direction of the individual tank, significantly reducing manufacturing time and saving costs.

[0016] 2. In the assembly and welding process of the tank head, the present invention uses adjacent annular cylindrical sections as a jig for construction, which can solve the problem that the welding shrinkage of the head plates is difficult to control due to the large number of them, thus affecting the connection between the head and the tank body. Attached Figure Description

[0017] Figure 1 A schematic diagram of the overall structure of a C-type twin tank prepared by the manufacturing method of the LNG shipping C-type twin tank according to the present invention.

[0018] Figure 2 This is a schematic diagram of the assembly of the annular cylindrical section.

[0019] Figure 3 This is a schematic diagram of the assembly of the sealing head.

[0020] Figure 4 This is a schematic diagram of the assembly of the tank body.

[0021] Figure 5 This is a schematic diagram of the structure of a single tank obtained by segmented welding.

[0022] Figure 6 This is a schematic diagram of the cutting process for a single tank.

[0023] Figure 7 This is a structural diagram of a single tank equipped with compartments.

[0024] Figure 8 This is a schematic diagram of two individual tanks being connected.

[0025] Figure Labels 10. Tank body; 11. Annular cylindrical section; 111. First arc plate; 112. Second arc plate; 20. Head end; 21. Equatorial plate; 22. Temperate zone plate; 23. Polar zone plate; 31. Opening; 32. Bulkhead plate; 41. Longitudinal track; 42. Transverse track; 50. Roller structure. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0027] It should also be noted that, in order to avoid obscuring the present invention with unnecessary details, only the structures and / or processing steps closely related to the present invention are shown in the accompanying drawings, while other details that are not closely related to the present invention are omitted.

[0028] Additionally, it should be noted that the terms “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0029] like Figure 1 , Figure 2 and Figure 7 As shown, the present invention divides the C-type twin tank according to the convenience of construction process and the ease of assembly quality. The C-type twin tank is first divided into two individual tanks and a partition plate 32. Each individual tank is then divided into a cylindrical tank body 10 and a head 20. The tank body 10 is divided into multiple annular cylindrical sections 11 according to the manufacturing process. Each annular cylindrical section 11 is further divided into 3-5 cylindrical plate sections.

[0030] like Figures 2-8 As shown, a method for manufacturing a C-type catamaran storage tank for LNG shipping is provided, comprising the following steps: S1. Set up a track and a roller structure 50 that can move along the track on a platform for tank assembly, and press the cylinder plate and end plate according to the design dimensions. S2. Assemble and weld multiple cylindrical plates into an annular cylindrical section 11; using the annular cylindrical section 11 as a frame, install multiple end plates on the annular cylindrical section 11 to form an end cap; S3. Using a hoisting device, place the two annular cylindrical sections 11 coaxially on the two roller structures 50 respectively. Move the roller structures 50 along the track until the two annular cylindrical sections 11 are circumferentially aligned and then perform preliminary fixing on the two annular cylindrical sections 11. Then drive the roller structures 50 to rotate the annular cylindrical sections 11 around their axis and perform circumferential welding on the two annular cylindrical sections 11. S4. According to the processing operation of step S3, multiple annular cylindrical sections 11 are assembled and welded to form the cylindrical tank body 10 of the storage tank; at the same time, the annular cylindrical section 11 part of the sealing head 20 is placed on the roller structure 50, and according to the processing operation of step S3, the two sealing heads 20 are installed at both ends of the tank body 10 to form the first single tank. S5. Assemble the second single-unit tank according to steps S2 to S4; S6. Mark the installation position of the bulkhead 32 on the individual tank according to the design dimensions. Cut openings 31 for installing the bulkhead 32 on the two individual tanks respectively. After installing the bulkhead 32 at the opening 31 on one of the individual tanks, align the openings 31 of the two individual tanks and weld them to obtain the C-type twin tank.

[0031] Specifically, in step S1, the end cap plate includes an equatorial plate 21, a temperate plate 22, and a polar plate 23. Figure 3 ).

[0032] For example, such as Figure 2 As shown, the annular cylindrical section 11 is divided into 5 cylindrical plates, including a first arc plate 111 made of low-temperature resistant alloy steel and a second arc plate 112 made of ordinary carbon steel. Since the construction material for C-type twin-body tanks is generally low-temperature resistant alloy steel, which is relatively expensive, the positions on the tank used for installing the bulkhead 32 need to be cut off during subsequent manufacturing. Therefore, during the initial assembly of the annular cylindrical section 11, the second arc plate 112, made of a relatively inexpensive material, can be used in the portion that needs to be cut off later, according to the design dimensions. This allows the second arc plate 112 to fill the parts that need to be cut off later during the initial assembly of the individual tanks, so that the four first arc plates 111 and one second arc plate 112 form the annular cylindrical section 11. The sidewall of the annular cylindrical section 11 can then be placed on the roller structure 50, allowing the annular cylindrical section 11 to rotate under the action of the roller structure 50, facilitating automated circumferential welding of the two sections. This improves the construction efficiency and manufacturing precision of the C-type twin-body tank, ensuring construction quality while reducing construction costs. In addition, the second arc plate 112 that is subsequently cut off can be reused, further saving construction costs.

[0033] Specifically, in step S1, the track includes a transverse track 42 and a longitudinal track 41. Both the transverse track 42 and the longitudinal track 41 include two spaced guide rails, wherein the longitudinal track 41 is arranged along the axial direction of the individual tank. Figure 8 The roller structure 50 is mounted on the track via a slider, allowing it to move along either the transverse track 42 or the longitudinal track 41. For example, the slider has a groove at its bottom. When the slider moves along the longitudinal track 41 to the junction of the longitudinal track 41 and the transverse track 42, its orientation can be adjusted so that it is no longer engaged on the longitudinal track 41 but on the transverse track 42, thus allowing it to move along the transverse track 42. Alternatively, when adjusting the slider's orientation, the tank can be supported by a bracket, allowing the slider to move along the transverse track 42, thereby adjusting the relative positions of the individual tanks during subsequent docking of two individual tanks.

[0034] Taking the longitudinal track 41 as an example, the roller structure 50 includes a frame perpendicular to the longitudinal track 41, rollers symmetrically arranged at both ends of the frame, and a drive component for driving the rollers to rotate.

[0035] Specifically, in step S2, the specific operation of assembling and welding multiple cylindrical plates into an annular cylindrical section 11 is as follows: an assembly jig is set up based on the diameter of the tank body 10, and four first arc plates 111 and second arc plates 112 are assembled in sequence to form an annular cylindrical section 11, and the connection between two adjacent arc plates is welded.

[0036] Specifically, such as Figure 3 As shown, in step S2, the manufacturing process of the head 20 is as follows: the annular cylindrical section 11 is placed vertically, so that the axis of the annular cylindrical section 11 is parallel to the vertical direction. Using the annular cylindrical section 11 as a frame, multiple equatorial plates 21, multiple temperate plates 22 and multiple polar plates 23 are assembled and welded in sequence in the circumferential direction to form the equator, temperate zone and polar zone in the vertical upward direction. The equator, temperate zone and polar zone together form a hemispherical head, and then the welding of the hemispherical head and the annular cylindrical section 11 adjacent to the hemispherical head is completed to form the head 20. By welding the hemispherical head onto the annular cylindrical section 11, it is easier to use the roller structure 50 to drive the annular cylindrical section 11 to rotate, thereby rotating the head 20 and quickly completing the welding and fixing of the head 20 to the tank body 10. At the same time, by using the annular cylindrical section 11 adjacent to the hemispherical head as a jig for assembling and welding the hemispherical head, the problem of difficult-to-control welding shrinkage due to the large number of head plates, which affects the docking of the hemispherical head and the tank body, can be solved.

[0037] Specifically, in step S3, the preliminary fixing process involves using several fasteners to fix the edges of the two cylinder sections so that when the two roller structures 50 are driven to rotate in sync, the two annular cylinder sections 11 can rotate synchronously for circumferential welding. Furthermore, the preliminary fixing process can fix the two annular cylinder sections 11 into one piece, thereby improving the stability of the annular cylinder sections 11 during rotation.

[0038] Specifically, in step S3, the welding process involves tack welding and root pass welding of the circumferential seam of the two annular cylinder sections 11 in sequence. After the root pass welding is completed, automatic submerged arc welding is used to complete the circumferential welding of the two annular cylinder sections 11. No root pass welding is performed between the second arc plates 112 of the two annular cylinder sections 11 to facilitate subsequent dismantling.

[0039] For example, such as Figure 4 and Figure 5As shown, the tank body 10 of the single-unit tank of the present invention is composed of six annular cylindrical sections 11, which are sequentially divided into a first cylindrical section, a second cylindrical section, a third cylindrical section, a fourth cylindrical section, a fifth cylindrical section, and a sixth cylindrical section along the horizontal direction. During the assembly and welding of the tank body 10, the first and second cylindrical sections are first placed coaxially on two roller structures 50 located on the longitudinal track 41. The roller structures 50 are moved along the longitudinal track until the two cylindrical sections are aligned and initially fixed. Then, the two roller structures 50 synchronously drive the two cylindrical sections to rotate for welding the first and second cylindrical sections. After welding, the welded first and second cylindrical sections are supported by a bracket. One roller structure 50 is moved out along the longitudinal track 41, and the position of the other roller structure 50 is adjusted so that it is located in the middle of the whole composed of the first and second cylindrical sections. After the third cylindrical section is hoisted onto the moved-out roller structure 50, the moved-out roller structure 50 is moved along the longitudinal track 41 to drive the third cylindrical section to align with the side of the second cylindrical section away from the first cylindrical section and to fix it initially. At the same time, the support is removed, and the two roller structures 50 are used to drive the cylindrical section to rotate synchronously to weld the second and third cylindrical sections. The welding of subsequent cylindrical sections is carried out in sequence according to the above welding process of the second and third cylindrical sections to complete the assembly of the tank body 10.

[0040] Then, using the bracket to support the tank body 10, the position of the roller structure 50 is moved so that the tank body 10 is placed on one roller structure 50, and the annular cylindrical section 11 of the sealing head 20 is placed on another roller structure 50. After the annular cylindrical section 11 of the sealing head 20 is aligned with the first cylindrical section and initially fixed, the sealing head 20 is welded to the tank body 10 by synchronously driving the two roller structures 50 to rotate. The other sealing head 20 is placed on the roller structure 50 located on the longitudinal track 41. After the roller structure 50 is moved until the other sealing head 20 is aligned with the sixth cylindrical section and initially fixed, the three roller structures 50 are synchronously driven to rotate to weld the other sealing head 20 to the tank body 10, thus completing the assembly of the single tank.

[0041] For example, after assembling the individual tanks, the two individual tanks can be moved along the longitudinal track 41 to the intersection of the longitudinal track 41 and the transverse track 42 and the two individual tanks can be horizontally aligned. Using the central axis of the individual tanks as a reference, an electronic theodolite is used to measure and locate the installation position of the bulkhead 32 and mark it. A handheld plasma cutter is used to cut along the marked line so that an opening 31 is formed on the opposite side of the two individual tanks. The bulkhead 32 is installed at the opening 31 of one of the individual tanks. Figure 6 , Figure 7 ); Keep the individual tank without the bulkhead 32 stationary, and move the individual tank with the bulkhead 32 along the transverse track 42 until the openings 31 of the two individual tanks are aligned ( Figure 8Welding yields the C-type twin-tank. By using a track to assemble the two individual tanks, the tank without baffles (32) remains stationary while the tank with baffles (32) is moved for assembly. This solves the problem of poor assembly precision between tanks and also avoids tank deformation caused by moving the tank without baffles (32).

[0042] Specifically, when the individual tanks are assembled and welded, the slider is located on the longitudinal track 41. The individual tanks with the partition plates 32 can be supported by the bracket. The position of the slider is adjusted so that the slider is changed from being locked on the longitudinal track 41 to being locked on the transverse track 42. This allows the slider to move along the transverse track 42 to dock the two individual tanks.

[0043] 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.

Claims

1. A method for manufacturing a C-type catamaran storage tank for LNG shipping, characterized in that, Includes the following steps: S1. A track and a roller structure that can move along the track are set on a platform for tank assembly, and the cylindrical section plate and end plate are pressed according to the design dimensions; the track includes a transverse track and a longitudinal track, and the roller structure is set on the track by a slider, so that the roller structure can move along the transverse track or the longitudinal track. S2. Assemble and weld multiple cylindrical plates into an annular cylindrical section; using the annular cylindrical section as a frame, install multiple end plates on the annular cylindrical section to form an end cap; S3. Place the two annular sections coaxially on the two roller structures respectively, and move the roller structures along the track until the two annular sections are circumferentially aligned. Then, perform preliminary fixing on the two annular sections. Next, use the roller structures to drive the two annular sections to rotate synchronously around their axis and perform circumferential welding on the two annular sections. S4. According to the processing operation of step S3, multiple annular cylindrical sections are assembled and welded to form a cylindrical tank body; at the same time, the annular cylindrical section of the sealing head is placed on the roller structure, and according to the processing operation of step S3, the two sealing heads are installed at both ends of the tank body to form the first single tank. S5. Assemble the second single-unit tank according to steps S2 to S4; S6. Cut openings on the two individual tanks respectively, install the bulkhead on the opening of one of the individual tanks, and then align and weld the openings of the two individual tanks to obtain the C-type twin tank.

2. The method for manufacturing the LNG shipping C-type catamaran storage tank according to claim 1, characterized in that: In step S1, the end cap plate includes an equatorial plate, a temperate plate, and a polar plate.

3. The method for manufacturing the LNG shipping C-type catamaran storage tank according to claim 1, characterized in that: In step S1, the cylindrical plate includes a first arc plate made of low-temperature resistant alloy steel and a second arc plate made of ordinary carbon steel for installation at the corresponding opening position.

4. The method for manufacturing the LNG shipping C-type catamaran storage tank according to claim 3, characterized in that: In step S3, the welding process involves sequentially performing spot welding, root pass welding, and submerged arc welding on the two annular cylinder sections.

5. The method for manufacturing the LNG shipping C-type catamaran storage tank according to claim 3, characterized in that: No root pass welding was performed between the second arc plates of the two annular cylindrical sections.

6. The method for manufacturing the LNG shipping C-type catamaran storage tank according to claim 1, characterized in that: In step S3, the preliminary fixing process involves using several fasteners to fix the two annular cylinder sections.

7. The method for manufacturing the LNG shipping C-type catamaran storage tank according to claim 1, characterized in that: In step S6, the specific operation of aligning the openings of the two individual tanks is as follows: keep the individual tank without the bulkhead stationary, and move the individual tank with the bulkhead installed until the openings of the two individual tanks are aligned.

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