A welding method for anti-slip blocks of a type C marine LNG storage tank

Abstract

This invention relates to the field of marine technology, specifically to a welding method for anti-shift blocks on a Type C marine LNG storage tank, comprising the following steps: S1, the tank section is horizontally arranged, and a line is drawn on the tank section at the installation position of the anti-shift block; S2, the anti-shift block segment is hoisted and fitted to the marked line; S3, a first movable clamp or a second movable clamp is installed on the edge of the tank section above the first lifting clamp, and a first connecting rod is used to connect the first movable clamp and the first lifting clamp respectively; S4, the second movable clamp and the second lifting clamp are connected by a second connecting rod, and the right end of the anti-shift block segment is welded to the tank section; S5, steps S2 to S4 are repeated to install the remaining anti-shift block segments; S6, adjacent anti-shift block segments are welded sequentially, and each anti-shift block segment is welded to the tank section. The welding method for anti-shift blocks on a Type C marine LNG storage tank of this invention can reduce the site resources occupied by the anti-shift blocks and avoid the workload of welding and repairing the clamps after the temporary supports are removed.

Description

Technical Field

[0001] This invention relates to the field of marine technology, and specifically to a welding method for mounting anti-displacement blocks on a type C marine LNG storage tank. Background Technology

[0002] Marine Type C LNG storage tanks are equipped with anti-slip blocks at both ends of the cylinder, such as... Figure 1 and 2 As shown, the anti-displacement block is used to limit the forward and backward displacement of the storage tank within the ship's hold. When the anti-displacement block is welded to the tank body, temporary supports are generally required to temporarily fix the anti-displacement block and the tank body. This provides a reliable and uniform bevel for the welding of the anti-displacement block and reduces angular deformation after welding. However, the installation of temporary supports inevitably causes localized damage to the tank body. Even if the damaged areas can be repaired by welding later, some stress concentration will occur in the tank body, posing a potential threat to the safe operation of the LNG cryogenic tank. Therefore, during the manufacturing of pressure vessels, especially cryogenic LNG storage tanks, welding should be avoided as much as possible to install temporary supports or components, in order to reduce or avoid stress concentration problems caused by temporary localized welding repairs.

[0003] The existing method for installing anti-shift blocks involves: after the LNG tank is formed, it is placed upright on a saddle, with the tank approximately 1 meter above the ground. The installation position of the anti-shift blocks is measured and marked according to the drawings. The anti-shift blocks are then segmented (divided into several sections) and positioned using temporary lifting lugs and a hoist. Alternatively, the tank can be placed on a roller frame, and the anti-shift blocks are laid flat on the tank surface by rolling the tank and cooperating with a crane. After positioning the anti-shift blocks using either method, temporary support plates or supports must be welded to fix the blocks in place. Double-sided fillet welds are used between the anti-shift blocks and the tank. Both of these welding methods require the anti-shift blocks to be installed as a whole with the tank, consuming significant space. Furthermore, after the temporary supports or support plates are removed, numerous slips or damage are created on the surface of the tank, requiring repair welding. Because the repair welding area is a region of extremely uneven heating and cooling, significant stress concentration occurs in the repair welding area. Summary of the Invention

[0004] To address the aforementioned problems, the present invention aims to provide a welding method for anti-shift blocks of C-type marine LNG storage tanks, thereby solving the technical problem that the welding method for anti-shift blocks in the prior art occupies a large area and causes stress concentration at the locations where temporary supports or shims are removed from the surface of the tank.

[0005] The present invention provides a technical solution for a welding method for anti-slip blocks of a C-type marine LNG storage tank, wherein the anti-slip block comprises multiple anti-slip block segments that match the surface of the tank body sections of the LNG storage tank;

[0006] The welding method for the anti-slip block of a Type C marine LNG storage tank includes the following steps:

[0007] S1, the tank body sections are horizontally arranged, and lines are drawn at the installation positions of the anti-slip blocks on the tank body sections;

[0008] S2, clamp the first and second lifting clamps at the left and right ends of an anti-slip block segment respectively, connect the first and second lifting clamps with slings, and lift the anti-slip block segment to fit the marked line;

[0009] S3, a first movable clamp is installed on the edge of the tank section above the first lifting clamp, and the first movable clamp and the first lifting clamp are connected by a first connecting rod. The first connecting rod is arranged at an inclination towards the middle of the anti-slip block section, and the left end of the anti-slip block section is welded to the tank section. The sling at the left end of the anti-slip block section is then loosened.

[0010] S4, install a second movable clamp on the edge of the tank section above the second lifting clamp, and connect the second movable clamp and the second lifting clamp with a second connecting rod respectively. The second connecting rod is arranged at an inclination towards the middle of the anti-slip block section, and welds the right end of the anti-slip block section to the tank section. Loosen the sling at the right end of the anti-slip block section.

[0011] S5, Repeat steps S2 to S4 to install the remaining anti-displacement block segments;

[0012] S6, sequentially weld adjacent anti-slip block segments and each anti-slip block segment to the tank body section;

[0013] S7, remove the first hanger, the second hanger, the first movable clamp, the second movable clamp, and all connecting rods.

[0014] As a preferred embodiment, in step S2, both the first and second clamps are located at 1 / 4 of the distance from the end of the anti-displacement block segment.

[0015] As a preferred embodiment, in step S2, the two ends of the anti-shift block segment are adjusted by slings. If both ends of the anti-shift block segment match the marking line, a fillet weld is applied to the bevel of the anti-shift block segment to position the anti-shift block segment.

[0016] If the two ends of the anti-slip block segment cannot match the markings, weld the lower end of the anti-slip block segment to the tank section.

[0017] As a preferred embodiment, in step S2, if both ends of the anti-shift block segment match the scribed line, then the length of the fillet weld at the bevel of the anti-shift block segment is 50mm, the interval is 500mm, and the size of the weld bead is 8mm.

[0018] As a preferred embodiment, in step S2, if the two ends of the anti-slip block segment cannot match the marking line, a 50mm long fillet weld is applied to the inner side at a position 50mm from the lower end of the anti-slip block segment to connect it with the tank section.

[0019] As a preferred embodiment, in step S3, a first movable clamp is installed at the edge of the upper part of the tank section of the first clamp, at a position 1 / 8 of the horizontal distance from the first clamp to the anti-slip block section, and the first movable clamp is fixed by using an iron tip.

[0020] As a preferred embodiment, in step S3, the angle between the first connecting rod and the anti-slip block segment is between 60 and 70 degrees; in step S4, the angle between the second connecting rod and the anti-slip block segment is between 60 and 70 degrees.

[0021] As a preferred embodiment, in step S3, the angle between the first connecting rod and the anti-shift block segment is 70 degrees.

[0022] As a preferred embodiment, in step S3, after loosening the sling at the left end of the anti-shift block segment, the right end of the anti-shift block segment is radially moved towards the tank section by a crane, and the horizontal component force generated by the wire rope is used to press the anti-shift block against the tank. The crane is then lifted to adjust the height of the right end of the anti-shift block, so that the entire anti-shift block is precisely positioned and fitted against the surface of the tank section, and a positioning weld of about 50mm is applied for fixation.

[0023] As a preferred embodiment, in step S4, a second movable clamp is installed at the edge of the upper tank section of the second clamp, at a position 1 / 8 of the horizontal distance from the second clamp's anti-slip block section, and the second movable clamp is secured with an iron tip.

[0024] As a preferred embodiment, in step S4, the angle between the second connecting rod and the anti-shift block segment is 70 degrees.

[0025] As a preferred embodiment, in step S6, a double-sided welding method is used to sequentially weld the butt joints between adjacent anti-slip block segments and the fillet welds between each anti-slip block segment and the tank body section.

[0026] As a preferred option, a symmetrical first K-shaped bevel is made for the butt joint. First, the weld on the lower side of the first K-shaped bevel is welded to a depth of 1 / 3. Then, carbon arc gouging is used to clean the root inside the upper side of the first K-shaped bevel. After grinding and cleaning, the weld on the upper side of the bevel is welded to a depth of 2 / 3. Finally, the remaining welds on the lower side and the remaining welds in the upper side are welded in sequence.

[0027] As a preferred option, the corner joint between the anti-shift block segment and the cylinder wall is made with a symmetrical second K-shaped bevel. First, the weld on the lower side of the second K-shaped bevel is welded to a depth of 1 / 3. Then, carbon arc gouging is used to clean the root inside the upper side of the second K-shaped bevel. After grinding and cleaning, the weld on the upper side of the bevel is welded to a depth of 2 / 3. Finally, the remaining welds on the lower side and the remaining welds inside the upper side are welded in sequence.

[0028] As a preferred embodiment, after step S7, the distance from the anti-shift block to the closing opening is measured before the multiple tank sections are joined together, and the deviation between the measurement results and the dimensions specified in the drawings, as well as the cutting amount of the closing opening allowance, are verified.

[0029] Compared to existing technologies, the beneficial effects of this application are:

[0030] The welding method for anti-slip blocks of the C-type marine LNG storage tank disclosed in this application installs the anti-slip blocks during the tank section fabrication stage, controlling welding deformation. It utilizes slings and first and second lifting clamps to control the dimensional accuracy of the installation spacing and position of the anti-slip blocks at the front and rear of the tank, ensuring a good match between the anti-slip blocks and the saddle of the hull structure when the LNG storage tank is hoisted onto the ship. The sling hoisting method achieves installation of the anti-slip blocks with minimal or no protrusions. This invention reduces the installation cycle and site resources required for the anti-slip blocks; reduces or avoids the temporary supports installed during installation and the resulting protrusions and welding repair work after their removal; reduces or avoids stress concentration hazards caused by localized welding repairs in the C-type LNG storage tank, improving the safety of cryogenic storage tanks. Attached Figure Description

[0031] Figure 1 This is a structural schematic diagram of the welding method for the anti-shift block of a C-type marine LNG storage tank in the prior art;

[0032] Figure 2 yes Figure 1 Side view;

[0033] Figure 3 This is a schematic diagram of step S1;

[0034] Figure 4 This is a schematic diagram of steps S2 to S3;

[0035] Figure 5 This is a schematic diagram of step S4;

[0036] Figure 6 This is a schematic diagram of step S7.

[0037] Among them, 1. anti-slip block, 2. anti-slip block segment, 3. tank body section, 4. first lifting clamp, 5. second lifting clamp, 6. lifting sling, 7. first movable clamp, 8. first connecting rod, 9. second movable clamp, 10. second connecting rod. Detailed Implementation

[0038] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and are not intended to limit the scope of the invention.

[0039] A preferred embodiment of the welding method for anti-slip blocks of a C-type marine LNG storage tank according to the present invention is provided. The anti-slip block in this application includes multiple anti-slip block segments that match the surface of the tank body sections of the LNG storage tank. Before welding, a measuring tape and a marking tool are prepared. A circumferential butt joint of a tank body section with anti-slip blocks is selected as the final closing joint of the tank body. The closing joint has a margin of about 15mm.

[0040] The welding method for the anti-shift blocks of Type C marine LNG storage tanks includes the following steps: (e.g.) Figures 2 to 6 As shown,

[0041] S1. During the manufacturing and installation of the LNG storage tank sections, the tank sections are horizontally positioned with open ends at both the top and bottom. A line is drawn at the installation location of the anti-slip block on the tank section, specifically in the shape of an arc.

[0042] S2, clamp the first and second lifting clamps at the left and right ends of an anti-slip block segment respectively, connect the first and second lifting clamps with slings, use a crane to connect the slings, lift the anti-slip block segment to fit the marked line, and use the crane to move the anti-slip block segment to fit as close to the marked line as possible for rough positioning.

[0043] During installation, both the first and second hangers are located at 1 / 4 of the distance from the end of the anti-displacement block segment.

[0044] In this process, the ends of the anti-shift block segment are adjusted using slings. Due to the limitations of the crane's movement accuracy, the ends of the anti-shift block segment generally cannot perfectly align with the marked lines. During the actual hoisting process, if both ends of the anti-shift block segment align with the marked lines, a fillet weld is applied to the bevel of the anti-shift block segment to position it. The fillet weld is 50mm long, spaced 500mm apart, and has an 8mm weld angle for initial positioning. If the ends of the anti-shift block segment do not align with the marked lines, the anti-shift block segment is moved until its higher end aligns with the marked lines on the tank section. A 50mm long fillet weld is then applied to the inner side of the lower end of the anti-shift block segment to connect it to the tank section, specifically at a position 50mm from the lower end of the anti-shift block segment, for initial positioning.

[0045] S3, install the first movable clamp on the edge of the tank section above the first lifting clamp, and connect the first movable clamp and the first lifting clamp with the first connecting rod respectively, and arrange the first connecting rod at an inclination towards the middle of the anti-shift block section, and weld the left end of the anti-shift block section to the tank section, fix the left end of the anti-shift block section, and then loosen the sling at the left end of the anti-shift block section.

[0046] In a specific embodiment of this application, a first movable clamp is installed at the edge of the upper part of the tank section of the first hanger, at a position 1 / 8 of the horizontal distance from the first hanger and at the position of the anti-slip block segment. The first movable clamp is fixed by pressing with an iron tip and is fixed by interference fit of the iron tip. The angle between the first connecting rod and the anti-slip block segment is 60 to 70 degrees. Preferably, the angle between the first connecting rod and the anti-slip block segment is 70 degrees.

[0047] Furthermore, after loosening the sling at the left end of the anti-slip block segment, the right end of the anti-slip block segment is radially moved towards the tank section using a crane. The horizontal force generated by the wire rope presses the anti-slip block firmly against the tank. The crane is then raised to adjust the height of the right end of the anti-slip block, ensuring precise alignment and fit between the entire anti-slip block and the surface of the tank section. A 50mm long locating weld is then applied for fixation, performing initial positioning of the anti-slip block segment. This positioning process primarily relies on the movement of the crane to position the anti-slip block segment.

[0048] In step S3 of this application, the connection between the first hanger, the second hanger, and the first movable clamp and the anti-slip block segment is achieved solely by utilizing the snap-fit ​​characteristics of the hanger and the movable clamp. It does not require welding or fixing to the tank body segment, thus avoiding damage to the tank body segment and the risk of stress concentration caused by removing the auxiliary tooling after the anti-slip block segment is installed.

[0049] S4, a second movable clamp is installed on the edge of the tank section above the second lifting clamp, and the second movable clamp and the second lifting clamp are connected by a second connecting rod. The second connecting rod is inclined towards the middle of the anti-slip block section, and the right end of the anti-slip block section is welded to the tank section. The lifting cable at the right end of the anti-slip block section is loosened. The inclination of the first connecting rod and the second connecting rod in opposite directions forms a trapezoidal structure with the edge of the tank section and the anti-slip block section, which has higher stability.

[0050] Specifically, a second movable clamp is installed at the edge of the upper tank section of the second hanger, at a position 1 / 8 of the horizontal distance from the second hanger's anti-slip block segment. The second movable clamp is then secured with an iron tip via an interference fit. In step S4, the angle between the second connecting rod and the anti-slip block segment ranges from 60 to 70 degrees, preferably 70 degrees. The second connecting rod is positioned opposite the first connecting rod, and the two connecting rods form a figure-eight shape.

[0051] In step S4 of this application, the connection between the first hanger, the second hanger, and the second movable clamp and the anti-slip block segment is achieved solely by utilizing the snap-fit ​​characteristics of the hanger and the movable clamp. It does not require welding or fixing to the tank body segment, thus avoiding damage to the tank body segment and the risk of stress concentration caused by removing the auxiliary tooling after the anti-slip block segment is installed.

[0052] In a specific embodiment of this application, the opening size of the first and second movable locking devices is slightly larger than the thickness of the anti-shift block by 1 mm, and the depth of the locking groove is approximately half the width of the anti-shift block, facilitating locking and fixing with the tank section. The first and second movable locking devices are welded and fixedly connected to the corresponding first and second connecting rods.

[0053] In other embodiments of this application, the first link and the second link can be configured as telescopic structures. Specifically, both the first link and the second link include a sleeve and a sleeve rod threaded into the sleeve. Rotating the sleeve rod can finely adjust the length of the first link or the second link, so as to make the adjustment of the anti-slip block segment more precise during the installation of the first link and the second link.

[0054] S5. Repeat steps S2 to S4 to install the remaining anti-displacement block segments.

[0055] S6, sequentially weld adjacent anti-slip block segments and each anti-slip block segment to the tank body section.

[0056] During the specific welding process, a double-sided welding method is used to weld the butt joints between adjacent anti-slip block segments and the fillet welds between each anti-slip block segment and the tank body section in sequence.

[0057] Furthermore, a symmetrical first K-shaped bevel is made for the butt joint. First, the weld on the lower side of the first K-shaped bevel is welded to a depth of 1 / 3. Then, carbon arc gouging is used to clean the root inside the upper side of the first K-shaped bevel. After grinding and cleaning, the weld on the upper side of the bevel is welded to a depth of 2 / 3. Finally, the remaining welds on the lower side and the remaining welds inside the upper side are welded in sequence.

[0058] Furthermore, a symmetrical second K-shaped bevel is made at the corner joint between the anti-shift block segment and the cylinder wall. First, the weld on the lower side of the second K-shaped bevel is welded to a depth of 1 / 3. Then, carbon arc gouging is used to clean the root inside the upper side of the second K-shaped bevel. After grinding and cleaning, the weld on the upper side of the bevel is welded to a depth of 2 / 3. Finally, the remaining welds on the lower side and the remaining welds inside the upper side are welded in sequence.

[0059] The double-sided welding method and corresponding welding sequence in step S6 of this application can precisely control the angular deformation of the anti-slip block segment, avoiding stress concentration and safety risks caused by excessive typical quantities during the welding process of the anti-slip block segment.

[0060] S7, remove the first and second lifting clamps, the first movable clamp, the second movable clamp, and all connecting rods. Simultaneously, before the multiple tank sections are joined together, measure the distance from the anti-slip block to the joining opening, and verify the deviation of the measurement results from the dimensions specified in the drawings, as well as the cutting amount of the joining opening allowance.

[0061] The present invention uses a translational lifting clamp, a self-made clamp, a connecting rod, and an iron tip to achieve the installation of the anti-slip block on the surface of the cylinder without a clamp, thereby reducing the amount of welding repair work and stress concentration problems caused by clamps in LNG tanks.

[0062] The welding method for the anti-shift block of the C-type marine LNG storage tank of the present invention uses a crane, crane rope, first lifting clamp, second lifting clamp, first movable clamp and second movable clamp to position and weld the anti-shift block segment, so as to realize the rapid and high-precision installation of the anti-shift block in advance during the cylinder section manufacturing stage; the first lifting clamp, second lifting clamp, first movable clamp and second movable clamp are all made from the tank body scraps, with fewer material requirements and restrictions, which can improve the comprehensive utilization rate of tank body materials.

[0063] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0064] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

[0065] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and substitutions can be made without departing from the technical principles of the present invention, and these improvements and substitutions should also be considered within the scope of protection of the present invention.

Claims

1. A method for welding and assembling anti-shift blocks for a type C marine LNG storage tank, characterized in that, The anti-slip block consists of multiple anti-slip block segments that match the surface of the tank body sections of the LNG storage tank; The welding method for the anti-slip block of a Type C marine LNG storage tank includes the following steps: S1, the tank body sections are horizontally arranged, and lines are drawn at the installation positions of the anti-slip blocks on the tank body sections; S2, clamp the first and second lifting clamps at the left and right ends of an anti-slip block segment respectively, connect the first and second lifting clamps with slings, and lift the anti-slip block segment to fit the marked line; S3, a first movable clamp is installed on the edge of the tank section above the first lifting clamp, and the first movable clamp and the first lifting clamp are connected by a first connecting rod. The first connecting rod is arranged at an inclination towards the middle of the anti-slip block section, and the left end of the anti-slip block section is welded to the tank section. The sling at the left end of the anti-slip block section is then loosened. S4, install a second movable clamp on the edge of the tank section above the second lifting clamp, and connect the second movable clamp and the second lifting clamp with a second connecting rod respectively. The second connecting rod is arranged at an inclination towards the middle of the anti-slip block section, and welds the right end of the anti-slip block section to the tank section. Loosen the sling at the right end of the anti-slip block section. S5, Repeat steps S2 to S4 to install the remaining anti-displacement block segments; S6, sequentially weld adjacent anti-slip block segments and each anti-slip block segment to the tank body section; S7, remove the first hanger, the second hanger, the first movable clamp, the second movable clamp, and all connecting rods.

2. The welding method for the anti-shift block of the C-type marine LNG storage tank according to claim 1, characterized in that: In step S2, both the first and second clamps are located at 1 / 4 of the distance from the end of the anti-displacement block segment.

3. The welding method for the anti-shift block of the C-type marine LNG storage tank according to claim 1, characterized in that: In step S2, the two ends of the anti-shift block segment are adjusted by slings. If both ends of the anti-shift block segment match the marking line, fillet welds are applied to the bevel of the anti-shift block segment to position the anti-shift block segment. If the two ends of the anti-slip block segment cannot match the markings, weld the lower end of the anti-slip block segment to the tank section.

4. The welding method for the anti-shift block of the C-type marine LNG storage tank according to claim 3, characterized in that: In step S2, if both ends of the anti-shift block segment match the marking line, then the length of the fillet weld at the bevel of the anti-shift block segment is 50mm, the interval is 500mm, and the size of the weld bead is 8mm.

5. The welding method for the anti-shift block of the C-type marine LNG storage tank according to claim 3, characterized in that: In step S2, if the two ends of the anti-slip block segment cannot match the marking line, a 50mm long fillet weld is applied to the inner side at a position 50mm from the lower end of the anti-slip block segment to connect it with the tank body section.

6. The welding method for the anti-shift block of a type C marine LNG storage tank according to claim 1, characterized in that: In step S3, a first movable clamp is installed at the edge of the upper part of the tank section of the first clamp, at a position 1 / 8 of the horizontal distance from the first clamp to the anti-slip block section, and the first movable clamp is fixed by using an iron tip.

7. The welding method for the anti-shift block of a type C marine LNG storage tank according to claim 1, characterized in that: In step S3, after the sling at the left end of the anti-shift block segment is loosened, the right end of the anti-shift block segment is radially moved towards the tank section by a crane, and the horizontal component force generated by the wire rope is used to press the anti-shift block against the tank. The crane is then lifted to adjust the height of the right end of the anti-shift block, so that the entire anti-shift block is precisely positioned and fitted against the surface of the tank section, and a positioning weld of about 50mm is applied for fixation.

8. The welding method for the anti-shift block of a type C marine LNG storage tank according to claim 1, characterized in that: In step S4, a second movable clamp is installed at the edge of the upper part of the tank section of the second clamp, at a position 1 / 8 of the horizontal distance from the second clamp and at the position of the anti-slip block section, and the second movable clamp is fixed by using an iron tip.

9. The welding method for the anti-shift block of a type C marine LNG storage tank according to claim 1, characterized in that: In step S3, the angle between the first connecting rod and the anti-slip block segment is between 60 and 70 degrees; in step S4, the angle between the second connecting rod and the anti-slip block segment is between 60 and 70 degrees.

10. The welding method for the anti-shift block of a type C marine LNG storage tank according to claim 1, characterized in that: In step S3, the angle between the first connecting rod and the anti-slip block segment is 70 degrees; in step S4, the angle between the second connecting rod and the anti-slip block segment is 70 degrees.

11. The welding method for the anti-shift block of a type C marine LNG storage tank according to claim 1, characterized in that: In step S6, a double-sided welding method is used to sequentially weld the butt joints between adjacent anti-slip block segments and the fillet welds between each anti-slip block segment and the tank body section.

12. The welding method for the anti-shift block of a type C marine LNG storage tank according to claim 11, characterized in that: For the butt joint, make a symmetrical first K-shaped bevel. First, weld the weld on the lower side of the first K-shaped bevel to a depth of 1 / 3. Then, use carbon arc gouging to clean the root inside the upper side of the first K-shaped bevel. After grinding and cleaning, weld the weld on the upper side of the bevel to a depth of 2 / 3. Finally, weld the remaining weld on the lower side of the bevel and the remaining weld inside the upper side of the bevel in sequence.

13. The welding method for the anti-shift block of a type C marine LNG storage tank according to claim 11, characterized in that: The corner joint between the anti-slip block segment and the cylinder wall is made with a symmetrical second K-shaped bevel. First, the weld on the lower side of the second K-shaped bevel is welded to a depth of 1 / 3. Then, carbon arc gouging is used to clean the root inside the upper side of the second K-shaped bevel. After grinding and cleaning, the weld on the upper side of the bevel is welded to a depth of 2 / 3. Finally, the remaining welds on the lower side and the remaining welds inside the upper side are welded in sequence.

14. The welding method for the anti-shift block of a type C marine LNG storage tank according to claim 1, characterized in that: After step S7, the distance from the anti-shift block to the closing opening is measured before the multiple tank sections are joined together, and the deviation between the measurement results and the dimensions specified in the drawings and the cutting amount of the closing opening allowance are checked.

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