A method for dividing a cargo hold bottom section of a 271,000 cubic meter membrane type LNG ship

Abstract

The present application relates to a kind of 271 million cubic meters film type LNG ship cargo hold bottom section division method, comprising: step 1, with the cargo hold bottom section division of the ship of close loading capacity as basis is divided;Step 2 includes: step 2.1, section assembly line width limit;Satisfy to carry out step 2.2, otherwise execute step 3;Step 2.2, lifting capacity limit;Satisfy to execute step 2.3, otherwise execute step 3;Step 2.3, construction period estimation, exceed the construction period set, then execute step 4, otherwise execute step 5;Step 3, increase width direction section division quantity, execute step 2;Step 4, reduce width direction section division quantity, execute step 2;Step 5, form division scheme.The present application is divided by the division mode of the existing ship of close loading capacity as basis, and effective division scheme is formed in combination with actual production infrastructure, and auxiliary ship period is built in the process of construction, and better production plan is formulated when the ship of greater loading capacity is built.

Description

Technical Field

[0001] This invention relates to the field of ship design, specifically to a method for dividing the bottom section of a 271,000 cubic meter membrane-type LNG carrier cargo hold. Background Technology

[0002] The 174,000 cubic meter membrane-type LNG carrier is a relatively mature design and application for ocean-going vessels. For ocean-going shipping, the larger the cargo capacity, the higher the efficiency. To further increase the efficiency of ocean-going shipping, a 271,000 cubic meter membrane-type LNG carrier has been introduced. Compared to the 174,000 cubic meter membrane-type LNG carrier, the 271,000 cubic meter membrane-type LNG carrier has an increased number of cargo holds, and the width and height of the vessel also increase accordingly. The hull bottom, as the "hull beam," is the main area bearing longitudinal bending and has very high strength requirements, resulting in a significant increase in the weight of the steel structure. For shipbuilding companies, their production infrastructure is relatively fixed. Replacing the production infrastructure for vessels with larger cargo capacities is too costly, and the original classification method can no longer meet the needs of building vessels with larger cargo capacities. Summary of the Invention

[0003] To meet the need for building larger-capacity vessels based on existing production infrastructure, this invention provides a method for dividing the bottom section of the cargo hold of a 271,000 cubic meter membrane-type LNG carrier. This method helps to formulate a production plan that conforms to the current production situation.

[0004] The technical objective of this invention is achieved through the following technical solution:

[0005] A method for dividing the bottom section of a 271,000 cubic meter membrane-type LNG carrier cargo hold, the method comprising:

[0006] Step 1: Divide the bottom section of the cargo hold of the 271,000 cubic meter membrane LNG carrier based on the existing bottom section division of the cargo hold of a membrane LNG carrier with a similar loading capacity;

[0007] Step 2: Determine whether the partitioning scheme meets the production infrastructure constraints, including:

[0008] Step 2.1: Determine if the segmented pipeline width limit is met; if it is met, proceed to Step 2.2; otherwise, proceed to Step 3.

[0009] Step 2.2: Determine if the lifting capacity limit is met; if it is met, proceed to Step 2.3; otherwise, proceed to Step 3.

[0010] Step 2.3: Construction period estimation. If the construction period exceeds the set construction period, proceed to step 4; otherwise, proceed to step 5.

[0011] Step 3: Increase the number of segments in the width direction, and then execute Step 2;

[0012] Step 4: Reduce the number of segments in the width direction, and then execute step 2;

[0013] Step 5: Develop a partitioning scheme.

[0014] Furthermore, the method also includes selecting the location of the closure joint at the solid rib plate position when dividing the ship's width direction, with the solid rib plate connecting the inner bottom plate and the outer plate.

[0015] Furthermore, when dividing the ship along its length, the longitudinal section is positioned close to the strong structure.

[0016] Furthermore, when dividing the area into segments, the entire keel tunnel area is divided into the same segment.

[0017] Furthermore, the distance between the dividing points in the central keel pipe area is ≥1000mm.

[0018] Furthermore, in step 2.3, the construction cycle is estimated by construction time, which is estimated according to the length of the weld seam of the segmented assembly, including the total time for cutting, assembling, welding and grinding operations at the closure joint.

[0019] Furthermore, the strong structure includes longitudinal girder and longitudinal skeleton.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] This invention divides the bottom section of the cargo hold of a 271,000 cubic meter membrane LNG carrier based on the existing division method of the bottom section of the cargo hold of LNG carriers with similar loading capacity. It forms an effective division scheme in combination with the actual production infrastructure, and assists the ship schedule in formulating better production plans when building ships with larger loading capacity. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the compartment division in the first division scheme of this invention.

[0023] Figure 2 This is a schematic diagram of the cargo hold bottom section division in the first division scheme of the present invention.

[0024] Figure 3 This is a schematic diagram of the cargo hold bottom section division in the second division scheme of the present invention.

[0025] In the diagram, 1 is compartment one; 2 is compartment two; 3 is compartment three; 4 is compartment four; 5 is compartment five; and 6 is the longitudinal dividing line. Detailed Implementation

[0026] The technical solution of the present invention will be further described below with reference to specific embodiments:

[0027] A method for dividing the bottom section of a 271,000 cubic meter membrane-type LNG carrier cargo hold, the method comprising:

[0028] Step 1: Divide the bottom section of the cargo hold of the 271,000 cubic meter membrane LNG carrier based on the existing bottom section division of the cargo hold of a membrane LNG carrier with a similar loading capacity;

[0029] In this embodiment, a 174,000 cubic meter membrane-type LNG carrier is used as an example of a vessel with a similar loading capacity. Existing 174,000 cubic meter membrane-type LNG carriers are divided into five sections along their length, using the transverse bulkheads as the dividing points. In the width direction, each section is divided into three longitudinal dividing lines, and in the length direction, each section is further divided into three segments, resulting in 12 segments per section. Following this method, the bottom section of the cargo hold of a 271,000 cubic meter membrane-type LNG carrier is divided to form the first division scheme. Figure 1 As shown, along the length of the ship, the sections are sequentially labeled as: Section 1 (1), Section 2 (2), Section 3 (3), Section 4 (4), and Section 5 (5); Figure 2 As shown, three longitudinal dividing lines 6 are set in the width direction, and the longitudinal dividing lines 6 extend along the length direction of the ship. Each section forms 12 segments, among which the bottom structure of section three has the largest weight, with a total weight estimated at 2116 tons. The weights of the 12 segments of section three are 187 tons, 202 tons, 191 tons, 139 tons, 151 tons, 143 tons, 166 tons, 182 tons, 175 tons, 187 tons, 202 tons, and 191 tons, respectively. The width of the largest segment is 18.675 meters, and the largest weight is 202 tons.

[0030] Step 2: Determine whether the partitioning scheme meets the production infrastructure constraints, including:

[0031] Step 2.1: Segmented pipeline width limit; if satisfied, proceed to Step 2.2; otherwise, proceed to Step 3.

[0032] Step 2.2, hoisting capacity limitations; if met, proceed to step 2.3; otherwise, proceed to step 3.

[0033] Step 2.3: Construction period estimation. If the construction period exceeds the set construction period, proceed to step 4; otherwise, proceed to step 5.

[0034] Step 3: Increase the number of segments in the width direction, and then execute Step 2;

[0035] Step 4: Reduce the number of segments in the width direction, and then execute step 2;

[0036] Step 5: Develop a partitioning scheme.

[0037] Based on the method in step 2, the width of the segmented production line is currently limited to 23 meters, and the lifting capacity of the gantry crane in the field is 300 tons.

[0038] The width and weight of the first division scheme currently meet the 23-meter width limit and 300-ton lifting capacity limit of the segmented assembly line.

[0039] When estimating the construction period for the first segmentation scheme, the construction time is estimated based on the length of the weld seam at the joint of the segmented assembly. This includes the total time for cutting, assembling, welding, and grinding at the joint location. The estimation is based on historical construction time statistics to calculate the average construction time per meter. This average is then used to calculate the construction time required under the first segmentation scheme. The required construction period is estimated by combining the construction time with the personnel configuration. That is, with the same personnel configuration, a longer construction time results in a longer construction period. If the construction period exceeds the set timeframe, the number of segments in the width direction needs to be reduced to shorten the required time.

[0040] The first division plan is estimated to require 13,000 total man-hours. Based on the current staffing, such as 20 people working 8 hours a day, it would take 13,000 / 20 / 8 = 81.25 days, which exceeds the expected construction period of 60 days.

[0041] Since the space for adjustment along the length of the hull is relatively small, a second scheme is considered by reducing the number of sections along the width. This results in two longitudinal dividing lines, forming the second division scheme. Figure 3 As shown, two longitudinal dividing lines 6 are set in the width direction, and the longitudinal dividing lines 6 extend along the length direction of the ship. Each compartment forms 9 segments, among which the bottom structure of compartment three has the largest weight, with a total weight estimated at 2116 tons. The weights of the 9 segments of compartment three are 232 tons, 252 tons, 242 tons, 217 tons, 228 tons, 219 tons, 232 tons, 252 tons, and 242 tons, respectively. In this embodiment, the distance between the two longitudinal dividing lines is 18400 mm, the distance of the longitudinal dividing lines from the side of the hull is 17600 mm, the width of the largest segment is 18.4 meters, and the maximum weight is 252 tons. Both the maximum width and the maximum weight meet the production infrastructure constraints.

[0042] It should be noted that the choice of the position of the longitudinal section line is not unique. For example, in the second division scheme in this embodiment, the distance between the two longitudinal section lines is 18400mm. If the distance between the two longitudinal section lines is greater or less than 18400mm but the division result still meets the conditions, then the choice of the position of the longitudinal section line is also acceptable.

[0043] To estimate the construction time for the second division scheme, the construction time is estimated based on the length of the weld seam of the assembled segments. If the construction time exceeds the set construction time, the number of segments in the width direction needs to be reduced to shorten the required construction time.

[0044] By estimating that the second division scheme requires 8,000 total man-hours, and based on the current staffing of 20 people working 8 hours a day, it would take 8,000 / 20 / 8 = 50 days, which meets the expected construction period of 60 days. Therefore, the second division method meets the requirements and saves 38.5% of the construction period compared to the first division method.

[0045] When selecting the division locations, it is also necessary to consider that, when dividing in the beam direction, the location of the closure joint should be chosen at the solid rib plate. The solid rib plate connects the inner bottom plate and the outer plate, forming a square frame structure with high structural strength, which helps prevent deformation during section placement and control deformation during hoisting. When dividing in the length direction, the longitudinal section should be placed close to the strong structure, which includes longitudinal girder and longitudinal skeleton, to ensure the strength of the section.

[0046] As a preferred option, when dividing the area into sections, the central keel pipe area should be completely divided within the same section, with a spacing of ≥1000mm between the central keel pipe area and the division point. This is to avoid damage to the fiberglass pipes in the central keel pipe area during welding and cutting operations, and to meet the pre-installation needs of the central keel pipe area during the section construction stage, thereby further improving construction efficiency.

[0047] This embodiment is merely a further explanation of the present invention and is not intended to limit the present invention. Those skilled in the art can make non-inventive modifications to this embodiment as needed after reading this specification, but such modifications are protected by patent law as long as they are within the scope of the claims of the present invention.

Claims

1. A method for dividing the bottom section of a 271,000 cubic meter membrane-type LNG carrier cargo hold, characterized in that, The method includes: Step 1: Based on the existing membrane-type LNG carriers with similar loading capacities, divide the bottom section of the cargo hold of the 271,000 cubic meter membrane-type LNG carrier into sections. The existing 174,000 cubic meter membrane-type LNG carriers are divided into 5 sections along the length of the ship, using the transverse bulkhead position as the dividing point. In the width direction, divide the 174,000 cubic meter membrane-type LNG carrier into 5 sections along the length of the ship. In the width direction, divide each section into three segments according to three longitudinal dividing lines. That is, each section forms 12 segments. Step 2: Determine whether the partitioning scheme meets the production infrastructure constraints, including: Step 2.1: Determine if the segmented pipeline width limit is met; if it is met, proceed to Step 2.2; otherwise, proceed to Step 3. Step 2.2: Determine if the lifting capacity limit is met; if it is met, proceed to Step 2.3; otherwise, proceed to Step 3. Step 2.3: Construction period estimation. If the construction period exceeds the set construction period, proceed to step 4; otherwise, proceed to step 5. Step 3: Increase the number of segments in the ship's width direction, and then execute Step 2; Step 4: Reduce the number of segments in the ship's width direction, and then proceed to step 2; Step 5: Develop a partitioning scheme.

2. The method for dividing the bottom section of a 271,000 cubic meter membrane-type LNG carrier cargo hold according to claim 1, characterized in that, The method also includes selecting the location of the closure joint at the solid rib plate when dividing the ship's width, with the solid rib plate connecting the inner bottom plate and the outer plate.

3. The method for dividing the bottom section of a 271,000 cubic meter membrane-type LNG carrier cargo hold according to claim 1, characterized in that, When dividing the ship along its length, the longitudinal section is positioned close to the strong structure.

4. The method for dividing the bottom section of a 271,000 cubic meter membrane-type LNG carrier cargo hold according to claim 1, characterized in that, When dividing the area into segments, the entire keel tunnel area should be divided into the same segment.

5. The method for dividing the bottom section of a 271,000 cubic meter membrane-type LNG carrier cargo hold according to claim 4, characterized in that, The distance between the designated locations in the central keel pipe area shall be ≥1000mm.

6. The method for dividing the bottom section of a 271,000 cubic meter membrane-type LNG carrier cargo hold according to claim 1, characterized in that, In step 2.3, the construction cycle is estimated by construction time. The construction time is estimated according to the length of the weld seam of the segmented assembly, including the total time for cutting, assembling, welding and grinding at the closure joint.

7. The method for dividing the bottom section of a 271,000 cubic meter membrane-type LNG carrier cargo hold according to claim 3, characterized in that, The strong structure includes longitudinal girder and longitudinal skeleton.

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