LNG ship liquid dome deck block carrying positioning precision control method

Abstract

The invention discloses an LNG ship liquid dome deck block carrying positioning precision control method which comprises the steps that an outer deck middle assembly in a liquid dome small segment and a liquid dome trepanning segment are built on the same tire, and the outer deck middle assembly and the liquid dome trepanning segment are hoisted away; a first center point located at the design position of the center point of the manhole is marked on the reinforcing device; a second center point located at the design position of the center point of the pump tower base is marked on the bottom subsection; establishing a three-dimensional coordinate system by taking the second central point as a coordinate origin; the liquid dome trepanning section is hoisted, and when the deviation of the coordinate value of the first center point does not exceed 2 mm, constraint welding and assembling are conducted on the liquid dome trepanning section; splicing and manufacturing a stainless steel deck and an opening according to the design size; manufacturing of small segments of the liquid dome and trepanning on an assembly medium carbon steel main plate in an outer deck are completed; and hoisting the small sections of the liquid dome to finish cabin sealing. The ship liquid dome deck block carrying positioning precision is improved, operation is easy, working efficiency is high, and the ship building period is shortened.

Description

Technical Field

[0001] The present invention relates to the technical field of shipbuilding, and in particular to a method for controlling the mounting positioning accuracy of a liquid dome deck section of an LNG ship. Background Art

[0002] LNG carrier is a special ship that transports liquefied gas at a low temperature of -162 degrees Celsius. Figure 1 As shown, during the construction of the LNG ship, the LNG ship liquid dome deck section 1 includes a liquid dome opening section 11 and a liquid dome sub-segment 12. The liquid dome sub-segment 12 is embedded in the opening of the liquid dome opening section 11. The opening in the liquid dome opening section 11 is used for the inlet and outlet of the pump tower. After the pump tower is hoisted, the liquid dome sub-segment 12 is hoisted to the opening of the liquid dome opening section 11 to complete the final sealing action. In order to ensure that the liquid dome small segment 12 and the liquid dome opening segment 11 can be accurately docked, the outer deck middle assembly in the liquid dome small segment 12 is currently built at the same time as the liquid dome opening segment 11. The liquid dome opening segment 11 and the outer deck middle assembly are hoisted together. After the liquid dome opening segment 11 is loaded, the outer deck middle assembly is separated and hoisted. The liquid dome small segment 12 is manufactured based on the outer deck middle assembly, and the opening position of the liquid dome small segment 12 is corrected according to the accuracy deviation of the dome deck opening segment 11 before the opening is carried out. The conventional installation of liquid dome deck sections on LNG ships has the following shortcomings: the accuracy of the liquid dome opening segment 11 during the installation process cannot be effectively guaranteed, and there is generally a positioning error of nearly 10mm in the corresponding ship length and ship width directions; it needs to be repeatedly hoisted and assembled on the outer deck, which is complicated and has low work efficiency; the opening position on the liquid dome small segment 12 needs to be determined after the liquid dome opening segment 11 is installed, and the final position of the manhole in the liquid dome small segment 12 is determined by checking the deviation between the corresponding deck sample punch position and the center position of the pump tower base, and the corresponding design size correction is made, so as to further complete the subsequent corresponding work of opening the liquid dome small segment 12, thereby extending the ship production cycle. Summary of the Invention

[0003] In response to the defects in the existing technology, the present application provides a method for controlling the positioning accuracy of the liquid dome deck section of an LNG ship to solve the technical problems in the existing technology such as poor accuracy, complex operation, low work efficiency, and long ship construction period of the liquid dome deck section of an LNG ship.

[0004] In order to achieve the purpose of the above invention, the technical solution provided by the present invention is as follows:

[0005] A method for controlling the positioning accuracy of a LNG carrier liquid dome deck section includes the following steps:

[0006] S1. After the outer deck middle assembly and the liquid dome opening segment in the liquid dome small segment are built together, the liquid dome opening segment is placed on the gantry in a normal position, the outer deck middle assembly is lifted off, and a reinforcement device is installed at the opening of the liquid dome opening segment;

[0007] S2. Marking a first center point on the reinforcing device, wherein the first center point is located at the designed position of the manhole center point;

[0008] S3. Mark a second center point on the bottom segment corresponding to the liquid dome opening segment, where the second center point is located at the designed position of the center point of the pump tower base;

[0009] S4. Using the second center point as the coordinate origin, establish a three-dimensional coordinate system using a total station, with the X-axis of the three-dimensional coordinate system along the length of the ship, the Y-axis of the three-dimensional coordinate system along the width of the ship, and the Z-axis of the three-dimensional coordinate system along the height of the ship;

[0010] S5. Hoist the liquid dome opening segment. The total station tracks the front and rear positions of the liquid dome opening segment in real time and records the coordinates of the first center point in the three-dimensional coordinate system. When the deviation between the X-axis coordinate value of the first center point and the design distance value between the manhole center point and the pump tower base center point in the ship length direction is no more than 2 mm, and when the deviation between the Y-axis coordinate value of the first center point and the design distance value between the manhole center point and the pump tower base center point in the ship width direction is no more than 2 mm, the liquid dome opening segment is hoisted into place. Under the premise that the four corners of the liquid dome opening segment are level, the liquid dome opening segment is positioned, and the liquid dome opening segment is constrainedly welded and assembled.

[0011] S6. Remove the reinforcement device and transfer it to the outer deck for assembly;

[0012] S7. Assemble and manufacture the stainless steel deck according to the designed dimensions, and make holes in the stainless steel deck according to the designed opening dimensions of the liquid dome sub-segments;

[0013] S8. Fix the stainless steel deck after the opening in S7 on the tire frame. Check the center line of the manhole, the center line of the segment, the rib inspection line and the tire frame ground line on the stainless steel plate. The deviation between the fixing position of the stainless steel plate and the tire frame and the design value shall not exceed 1mm.

[0014] S9. Combine the outer deck assembly with the stainless steel deck to complete the manufacture of the liquid dome small section;

[0015] S10, turning over the liquid dome sub-segment and adjusting the level of the liquid dome sub-segment, determining the final position and size of each opening on the stainless steel main plate according to the position and size of each opening and the theoretical center position of each opening, and completing the opening of the medium carbon steel main plate in the outer deck;

[0016] S11. After the pump tower is hoisted, the small segment of the liquid dome is hoisted to the opening of the liquid dome opening segment to complete the sealing operation of the liquid cargo tank.

[0017] In one embodiment, the reinforcing means in S1 include mutually perpendicular I-beams, which are fixed to the upper surface of the outer deck in the liquid dome opening segment.

[0018] In one embodiment, the S2 specifically includes: using the ship length direction reference line and the ship width direction reference line for manufacturing the liquid dome opening segment as the marking reference line, marking a first parallel line and a second parallel line on the reinforcement device, the first parallel line is parallel to the ship length direction marking reference line, the second parallel line is parallel to the ship width direction marking reference line, the distance between the first parallel line 15 and the ship length direction marking reference line is equal to the design distance between the manhole center point and the ship length direction reference line, the distance between the second parallel line and the ship width direction marking reference line is equal to the design distance between the manhole center point and the ship width direction reference line, the intersection of the first parallel line and the second parallel line is the first center point, the first center point is located at the design position of the manhole center point, and a laser reflector is attached to the first center point, and the eccentricity of the center of the laser reflector and the first center point is not less than 1 mm.

[0019] In one embodiment, the S3 specifically includes: drawing a third parallel line and a fourth parallel line on the bottom segment, the third parallel line is parallel to the compartment, the fourth parallel line is parallel to the center line of the bottom segment, the distance between the third parallel line and the compartment is equal to the design distance between the center point of the pump tower base and the compartment, the distance between the fourth parallel line and the center line of the bottom segment is equal to the design distance between the center point of the pump tower base and the center line of the bottom segment, and the intersection of the third parallel line and the fourth parallel line is the second center point.

[0020] In one embodiment, S4 also includes taking a check point on the center line of the bottom segment, checking the distance between the check point and the X-axis, and requiring that the deviation between the distance between the check point and the X-axis and the design distance between the center point of the pump tower base and the center line of the bottom segment does not exceed 1 mm.

[0021] In one embodiment, the S1 further includes setting a sample punch at the connection between the liquid dome opening segment 11 and the outer deck. In the S5 shown, during the constrained welding and assembly process of the liquid dome opening segment, the coordinates of the first center point and the sample punch in the three-dimensional coordinate system are monitored in real time, and the liquid dome opening segment is welded symmetrically to ensure that the deviation of the first center point and the sample punch does not exceed 2 mm during welding.

[0022] In one embodiment, after the liquid dome opening is assembled in sections in S5, the coordinates of the first center point and the sample punch in the three-dimensional coordinate system are checked, and it is required that the deviation between the X-axial coordinate value of the first center point and the design distance value between the manhole center point and the pump tower base center point in the ship length direction is no more than 2 mm, and the deviation between the Y-axial coordinate value of the first center point and the design distance value between the manhole center point and the pump tower base center point in the ship width direction is no more than 2 mm; the deviation between the X-axial coordinate value of the sample punch and the design distance value between the sample punch and the pump tower base center point in the ship length direction is no more than 2 mm, and the deviation between the Y-axial coordinate value of the sample punch and the design distance value between the sample punch and the pump tower base center point in the ship width direction is no more than 2 mm.

[0023] In one embodiment, the S7 specifically includes: inspecting the length, width and diagonal size of the entire stainless steel plate after splicing the stainless steel armor, requiring the deviation to be controlled within 0 to -2 mm, marking and confirming the center position of the holes contained in the liquid dome segment according to the panel size verification result, and completing the hole opening by the CNC cutting machine after determining the center position of each hole.

[0024] In one embodiment, in S7, the center position of the manhole is first determined, and then the center positions of other holes in the liquid dome segment are determined based on the center of the manhole. When drilling holes, the CNC cutting machine is controlled to drill holes according to the diameter tolerance of 0 to +2 mm under the requirements of the designed hole size.

[0025] In one embodiment, in S8, a stainless steel pad is provided between the stainless steel deck and the tire frame; in S11, the installation and inspection of the insulation boxes, primary membranes, and secondary membranes in each area of the liquid dome deck section are completed before the pump tower is hoisted.

[0026] Compared with the prior art, this application has at least the following beneficial effects:

[0027] The LNG ship liquid dome deck total section mounting positioning accuracy control method disclosed in the present application establishes a three-dimensional coordinate system with the second center point located at the center point of the pump tower base on the bottom section as the origin. When hoisting the liquid dome opening section, the coordinate value of the first center point located at the designed position of the manhole center point on the reinforcement device is tracked in real time. The coordinate value of the first center point is used as a basis for judging whether the liquid dome opening section is hoisted in place, thereby reducing the deviation of the liquid dome opening section mounting from the previous maximum deviation of 10 mm to about 2 mm, thereby improving the mounting positioning accuracy of the ship liquid dome deck total section.

[0028] The error in hoisting the liquid dome opening segment is small, and there is no need to determine the deviation between the liquid dome opening segment and the pump tower base and then correct the opening position on the liquid dome small segment, which greatly advances the manufacturing timing of the liquid dome small segment. In this application, there is no need to repeatedly hoist the outer deck of the liquid dome small segment for assembly, which is simple to operate and has high work efficiency, greatly shortening the construction period of the entire LNG ship. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a schematic structural diagram of the liquid dome deck section of an LNG carrier in an embodiment of the present application.

[0030] Figure 2 This is a schematic structural diagram of a liquid dome opening segment provided with a reinforcement device in an embodiment of the present application;

[0031] Figure 3 This is a top view of the bottom section in an embodiment of the present application.

[0032] Figure numerals: 1. LNG carrier liquid dome deck overall section; 11. Liquid dome opening section; 12. Liquid dome subsection; 13. Reinforcement device; 14. First center point; 15. First parallel line; 16. Second parallel line; 2. Bottom section; 21. Second center point; 22. Third parallel line; 23. Fourth parallel line. DETAILED DESCRIPTION

[0033] To make the objectives, technical solutions, and advantages of the present invention more clearly apparent, the present invention is described below using specific embodiments shown in the accompanying drawings. However, it should be understood that these descriptions are merely illustrative and are not intended to limit the scope of the present invention. In addition, in the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessary confusion of the concepts of the present invention.

[0034] The terms used in this disclosure are for the purpose of describing specific embodiments only and are not intended to limit the disclosure. As used in this disclosure and the appended claims, the singular forms "a," "an," "the," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It should also be understood that the term "and / or" as used herein refers to and encompasses any and all possible combinations of one or more of the associated listed items.

[0035] It should be understood that although the terms first, second, third, etc. may be used in this disclosure to describe various information, such information should not be limited to these terms and should not be understood to indicate or imply relative importance. These terms are only used to distinguish information of the same type from each other. For example, first information may also be referred to as second information, and similarly, second information may also be referred to as first information without departing from the scope of this disclosure. Depending on the context, the word "if" as used herein may be interpreted as "at the time of" or "when" or "in response to determining."

[0036] In the description of the present invention, unless otherwise specified and limited, it should be noted that the terms "installed", "connected" and "connected" should be understood in a broad sense. For example, it can be a mechanical connection or the internal communication between two components. It can be a direct connection or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to the specific circumstances.

[0037] In order to better understand the technical solution of the present invention, the present invention is described in detail below in conjunction with specific implementation methods.

[0038] The present application provides a method for controlling the positioning accuracy of a liquid dome deck section of an LNG carrier, comprising the following steps:

[0039] S1. After the outer deck middle assembly in the liquid dome small segment 12 and the liquid dome opening segment 11 are built at the same time, the liquid dome opening segment 11 is placed normally on the gantry, the outer deck middle assembly is lifted off, and a reinforcement device 13 is set at the opening of the liquid dome opening segment 11.

[0040] The reinforcement device 13 is provided at the opening of the liquid dome opening segment 11, which can effectively control the deformation of the opening of the liquid dome opening segment 11 during the subsequent lifting process. Figure 2 As shown, the reinforcement device 13 includes mutually perpendicular I-beams fixed to the upper surface of the outer deck in the liquid dome perforated segment 11 to avoid direct contact between the I-beams and the stainless steel inner deck, thereby preventing corrosion and contamination of the material. In this embodiment, a sample punch is provided at the connection between the liquid dome perforated segment 11 and the outer deck.

[0041] S2. Mark a first center point 14 on the reinforcing device 2. The first center point is located at the designed position of the manhole center point.

[0042] S2 specifically includes: taking the ship length direction reference line and the ship width direction reference line for manufacturing the liquid dome opening segment 11 as the marking reference lines, marking a first parallel line 15 and a second parallel line 16 on the reinforcement device 2, the first parallel line 15 is parallel to the ship length direction marking reference line, the second parallel line 16 is parallel to the ship width direction marking reference line, the distance between the first parallel line 15 and the ship length direction marking reference line is equal to the design distance between the manhole center point and the ship length direction reference line, the distance between the second parallel line 16 and the ship width direction marking reference line is equal to the design distance between the manhole center point and the ship width direction reference line, the intersection point of the first parallel line 15 and the second parallel line 16 is the first center point 14, the first center point 14 is located at the design position of the manhole center point, a laser reflective sheet is attached to the first center point 14, and the eccentricity between the center of the laser reflective sheet and the first center point 14 is not less than 1 mm.

[0043] S3. Mark a second center point 21 on the bottom segment 2 corresponding to the liquid dome opening segment 11. The second center point 21 is located at the designed position of the center point of the pump tower base.

[0044] S3 specifically includes: drawing a third parallel line 22 and a fourth parallel line 23 on the bottom segment 2, the third parallel line 22 is parallel to the compartment, the fourth parallel line 23 is parallel to the center line of the bottom segment 2, the distance between the third parallel line 22 and the compartment is equal to the design distance between the center point of the pump tower base and the compartment, the distance between the fourth parallel line 23 and the center line of the bottom segment 2 is equal to the design distance between the center point of the pump tower base and the center line of the bottom segment 2, and the intersection of the third parallel line 22 and the fourth parallel line 23 is the second center point.

[0045] S4. With the second center point 21 as the coordinate origin, a three-dimensional coordinate system is established by a total station, wherein the X axis of the three-dimensional coordinate system is along the direction of the ship length, the Y axis of the three-dimensional coordinate system is along the direction of the ship width, and the Z axis of the three-dimensional coordinate system is along the direction of the ship height.

[0046] In order to ensure the accuracy of the three-dimensional coordinate system, a check point is taken on the center line of the bottom segment 2, and the distance between the check point and the X-axis is checked. It is required that the deviation between the distance between the check point and the X-axis and the design distance between the center point of the pump tower base and the center line of the bottom segment 2 shall not exceed 1mm.

[0047] S5. Hoist the liquid dome opening segment 11. The total station tracks the front and rear positions of the liquid dome opening segment 11 in real time and records the coordinates of the first center point 14 in the three-dimensional coordinate system. When the deviation between the X-axis coordinate value of the first center point 14 and the design distance value between the manhole center point and the pump tower base center point in the ship length direction is no more than 2 mm, and when the deviation between the Y-axis coordinate value of the first center point 14 and the design distance value between the manhole center point and the pump tower base center point in the ship width direction is no more than 2 mm, the liquid dome opening segment 11 is hoisted into place. Under the premise that the four corners of the liquid dome opening segment 11 are level, the liquid dome opening segment 11 is positioned, and constrained welding and assembly are performed on the liquid dome opening segment 11.

[0048] In order to ensure the installation accuracy of the hoisting liquid dome opening segment 11, during the constrained welding and assembly process of the liquid dome opening segment 11, the coordinates of the first center point and the sample punch in the three-dimensional coordinate system are monitored in real time, and the liquid dome opening segment 11 is welded symmetrically to ensure that the deviation of the first center point and the sample punch does not exceed 2 mm during welding.

[0049] In order to improve the installation accuracy of the liquid dome opening segment 11, after the liquid dome opening segment 11 is assembled, the coordinates of the first center point and the sample punch in the three-dimensional coordinate system are checked, requiring that the deviation between the X-axis coordinate value of the first center point and the design distance value between the manhole center point and the pump tower base center point in the ship length direction is no more than 2mm, and when the Y-axis coordinate value of the first center point and the design distance value between the manhole center point and the pump tower base center point in the ship width direction is no more than 2mm; the X-axis coordinate value of the sample punch and the design distance value between the sample punch and the pump tower base center point in the ship length direction is no more than 2mm, and the Y-axis coordinate value of the sample punch and the design distance value between the sample punch and the pump tower base center point in the ship width direction is no more than 2mm. In this embodiment, after checking the first center point and the sample punch, the Z-axis coordinate value of the first center point is measured by a total station and compared with the theoretical height difference between the first center point and the second center point for analysis, which is used as the basis for cutting and processing the lower opening allowance when the subsequent pump tower base height is positioned.

[0050] S6. Remove the reinforcement device 13 and transfer it to the outer deck for assembly.

[0051] Removing the reinforcement 13 involves cutting the I-beam 20 mm from the outer deck of the liquid dome opening segment and then grinding the remaining I-beam to avoid damage to the outer deck during the removal process. While removing the reinforcement 13, a guardrail is installed around the opening of the liquid dome opening segment 11 to prevent safety accidents.

[0052] S7. Splice and manufacture the stainless steel deck according to the designed dimensions, and make holes in the stainless steel deck according to the designed opening dimensions of the liquid dome sub-segment 12.

[0053] S7 specifically includes: after splicing the stainless steel armor, inspecting the length, width and diagonal size of the entire stainless steel plate, requiring the deviation to be controlled within 0 to -2 mm, marking and confirming the center position of the holes contained in the liquid dome small segment 12 according to the panel size verification result. In this embodiment, the position of the manhole center is first determined, and then the center position of other holes in the liquid dome small segment 12 is determined based on the manhole center. After determining the center position of each hole, the CNC cutting machine is used to complete the hole opening. When opening the hole, the CNC cutting machine is controlled to open the hole according to the diameter tolerance of 0 to +2 mm under the requirements of the designed hole size.

[0054] S8. Fix the stainless steel deck after the opening in S7 on the tire frame, and check the manhole center line, segment center line, rib inspection line and tire frame ground line on the stainless steel plate. The deviation between the fixed position of the stainless steel plate and the tire frame and the design value must not exceed 1mm.

[0055] A stainless steel pad is provided between the stainless steel deck and the tire frame to separate the stainless steel deck and the tire frame to avoid galvanic corrosion caused by direct contact between the stainless steel plate and the tire frame.

[0056] S9. Combine the outer deck assembly with the stainless steel deck to complete the manufacture of the liquid dome sub-segment 12.

[0057] S10. Turn over the liquid dome sub-segment 12 and adjust the level of the liquid dome sub-segment 12. Determine the final position and size of each opening on the stainless steel main plate according to the position and size of each opening and the theoretical center position of each opening. Complete the assembly of the openings on the medium carbon steel main plate in the outer deck.

[0058] S11. After the pump tower is hoisted, the liquid dome sub-segment 12 is hoisted to the opening of the liquid dome opening segment 11 to complete the sealing operation of the liquid cargo tank.

[0059] In this embodiment, the installation and inspection of the insulation boxes, primary membranes, and secondary membranes in each area of the liquid dome deck section are completed before the pump tower is hoisted, thereby ensuring the integrity of the subsequent liquid cargo tank sealing.

[0060] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to preferred embodiments, ordinary technicians in the field should understand that the specific implementation methods of the invention can still be modified or some technical features can be replaced by equivalents without departing from the spirit of the technical solutions of the present invention. They should all be included in the scope of the technical solutions for which protection is sought in the present invention.

Claims

1. A method for controlling the positioning accuracy of the liquid dome deck section of an LNG carrier, characterized in that: The following steps are involved: S1. After the outer deck middle assembly and the liquid dome opening segment in the liquid dome small segment are built together, the liquid dome opening segment is placed on the gantry in a normal position, the outer deck middle assembly is lifted off, and a reinforcement device is installed at the opening of the liquid dome opening segment; S2. Marking a first center point on the reinforcing device, wherein the first center point is located at the designed position of the manhole center point; S3. Mark a second center point on the bottom segment corresponding to the liquid dome opening segment, where the second center point is located at the designed position of the center point of the pump tower base; S4. Using the second center point as the coordinate origin, establish a three-dimensional coordinate system using a total station, with the X axis of the three-dimensional coordinate system along the length of the ship, the Y axis of the three-dimensional coordinate system along the width of the ship, and the Z axis of the three-dimensional coordinate system along the height of the ship; S5. Hoist the liquid dome opening segment. The total station tracks the front and rear positions of the liquid dome opening segment in real time and records the coordinates of the first center point in the three-dimensional coordinate system. When the deviation between the X-axis coordinate value of the first center point and the design distance value between the manhole center point and the pump tower base center point in the ship length direction is no more than 2 mm, and when the deviation between the Y-axis coordinate value of the first center point and the design distance value between the manhole center point and the pump tower base center point in the ship width direction is no more than 2 mm, the liquid dome opening segment is hoisted into place. Under the premise that the four corners of the liquid dome opening segment are level, the liquid dome opening segment is positioned, and the liquid dome opening segment is constrainedly welded and assembled. S6. Remove the reinforcement device and transfer it to the outer deck for assembly; S7. Assemble and manufacture the stainless steel deck according to the designed dimensions, and make holes in the stainless steel deck according to the designed opening dimensions of the liquid dome sub-segments; S8. Fix the stainless steel deck after the opening in S7 on the tire frame. Check the center line of the manhole, the center line of the segment, the rib inspection line and the tire frame ground line on the stainless steel plate. The deviation between the fixing position of the stainless steel plate and the tire frame and the design value shall not exceed 1mm. S9. Combine the outer deck assembly with the stainless steel deck to complete the manufacture of the liquid dome small section; S10, turning over the liquid dome sub-segment and adjusting the level of the liquid dome sub-segment, determining the final position and size of each opening on the stainless steel main plate according to the position and size of each opening and the theoretical center position of each opening, and completing the opening of the medium carbon steel main plate in the outer deck; S11. After the pump tower is hoisted, the small segment of the liquid dome is hoisted to the opening of the liquid dome opening segment to complete the sealing operation of the liquid cargo tank.

2. The method for controlling the positioning accuracy of the LNG carrier liquid dome deck section according to claim 1 is characterized in that: The reinforcement device in S1 includes mutually perpendicular I-beams, which are fixed to the upper surface of the outer deck in the liquid dome opening segment.

3. The method for controlling the positioning accuracy of the LNG carrier liquid dome deck section according to claim 1 is characterized in that: The S2 specifically includes: using the ship length direction reference line and the ship width direction reference line for manufacturing the liquid dome opening segment as the marking reference line, marking a first parallel line and a second parallel line on the reinforcement device, the first parallel line is parallel to the ship length direction marking reference line, the second parallel line is parallel to the ship width direction marking reference line, the distance between the first parallel line 15 and the ship length direction marking reference line is equal to the design distance between the manhole center point and the ship length direction reference line, the distance between the second parallel line and the ship width direction marking reference line is equal to the design distance between the manhole center point and the ship width direction reference line, the intersection point of the first parallel line and the second parallel line is the first center point, the first center point is located at the design position of the manhole center point, and a laser reflective sheet is attached to the first center point, and the eccentricity between the center of the laser reflective sheet and the first center point is not less than 1 mm.

4. The method for controlling the positioning accuracy of the LNG carrier liquid dome deck section according to claim 3 is characterized in that: The S3 specifically includes: drawing a third parallel line and a fourth parallel line on the bottom segment, the third parallel line is parallel to the compartment, the fourth parallel line is parallel to the center line of the bottom segment, the distance between the third parallel line and the compartment is equal to the design distance between the center point of the pump tower base and the compartment, the distance between the fourth parallel line and the center line of the bottom segment is equal to the design distance between the center point of the pump tower base and the center line of the bottom segment, and the intersection of the third parallel line and the fourth parallel line is the second center point.

5. The method for controlling the positioning accuracy of the LNG carrier liquid dome deck section according to claim 1 is characterized in that: The S4 also includes taking a check point on the center line of the bottom segment and checking the distance between the check point and the X-axis, requiring that the deviation between the distance between the check point and the X-axis and the design distance between the center point of the pump tower base and the center line of the bottom segment does not exceed 1 mm.

6. The method for controlling positioning accuracy of the LNG carrier liquid dome deck section according to claim 1 is characterized in that: The S1 also includes setting a sample punch at the connection between the liquid dome opening segment 11 and the outer deck. In the S5 shown, during the constrained welding and assembly process of the liquid dome opening segment, the coordinates of the first center point and the sample punch in the three-dimensional coordinate system are monitored in real time, and the liquid dome opening segment is welded symmetrically to ensure that the deviation of the first center point and the sample punch does not exceed 2 mm during welding.

7. The method for controlling the positioning accuracy of the LNG carrier liquid dome deck section according to claim 6 is characterized in that: In said S5, after the liquid dome opening is assembled in sections, the coordinates of the first center point and the sample punch in the three-dimensional coordinate system are checked, requiring that the deviation between the X-axis coordinate value of the first center point and the design distance value between the manhole center point and the pump tower base center point in the ship length direction is not more than 2 mm, and the deviation between the Y-axis coordinate value of the first center point and the design distance value between the manhole center point and the pump tower base center point in the ship width direction is not more than 2 mm; the deviation between the X-axis coordinate value of the sample punch and the design distance value between the sample punch and the pump tower base center point in the ship length direction is not more than 2 mm, and the deviation between the Y-axis coordinate value of the sample punch and the design distance value between the sample punch and the pump tower base center point in the ship width direction is not more than 2 mm.

8. The method for controlling positioning accuracy of the LNG carrier liquid dome deck section according to claim 1 is characterized in that: The S7 specifically includes: after splicing the stainless steel armor, inspecting the length, width and diagonal size of the entire stainless steel plate, requiring the deviation to be controlled within 0 to -2 mm, marking and confirming the center positions of the holes contained in the liquid dome small segment according to the panel size verification results, and completing the hole opening by the CNC cutting machine after determining the center position of each hole.

9. The method for controlling the positioning accuracy of the LNG carrier liquid dome deck section according to claim 8 is characterized in that: In S7, the center position of the manhole is first determined, and then the center positions of other holes in the liquid dome segment are determined based on the center of the manhole. When drilling holes, the CNC cutting machine is controlled to drill holes according to the diameter tolerance of 0 to +2 mm under the requirements of the designed hole size.

10. The method for controlling positioning accuracy of a LNG carrier liquid dome deck section according to claim 1, characterized in that: In S8, a stainless steel pad is provided between the stainless steel deck and the tire frame; in S11, the installation and inspection of the insulation boxes, primary membranes, and secondary membranes in each area of the liquid dome deck section are completed before the pump tower is hoisted.

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