Method for installing pump well in cargo hold of NO96 type LNG (Liquefied Natural Gas) ship

Abstract

The invention discloses a method for installing a pump well in a cargo hold of an NO96 type LNG (Liquefied Natural Gas) ship. The method comprises the following steps: marking and positioning, and fixing bolts; the thickness of the resin and the supporting beam and the theoretical installation height of the pump well are determined according to the height of the leveling wedge block; fixing the clamp; laying resin on the surface of the hull, and placing a support beam on the upper surface of the resin; temporarily fixing the pump well through a clamp, and separating the clamp from the surface of the ship body after resin curing is finished; spot-welding and positioning the stop column on the surface of the ship body, removing the pump well, and completely welding the stop column on the surface of the ship body; and the pump well is placed on the supporting beam again, and the pump well is fixed. The pump well can be accurately installed in the LNG ship cargo hold of the NO96 type containment system, the amount of residual liquid in the NO96 type cargo hold is reduced, the operation economy is improved, and the integrity and continuity of an invar steel film in the LNG ship cargo hold are further guaranteed.

Description

Technical Field

[0001] This invention relates to the field of shipbuilding technology, and in particular to a method for installing pump wells in the cargo hold of a NO96 type LNG ship. Background Technology

[0002] To improve the operational economics of LNG carriers, it is essential to minimize the amount of residual liquid in the cargo holds during ballast voyages. To address this issue, vessels equipped with the Mark III cargo containment system utilize specially designed pump wells in the bilge to allow deep-well pumps to more thoroughly extract LNG, effectively reducing residual liquid levels.

[0003] However, this solution is difficult to apply to LNG carriers using the NO96 cargo containment system. The fundamental reason lies in the difference in their core technologies: the Mark III system uses a secondary and primary barrier composed of reinforced polyurethane foam and plywood, making it easier to integrate pump wells; while the NO96 system relies on Invar steel membrane primary and secondary barriers supported by hundreds of prefabricated plywood boxes embedded in the hull. Its structure is rigid and precise, and adding pump wells at the bottom would compromise the integrity and continuity of the Invar steel membrane, posing unacceptable safety risks. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this application provides a method for installing pump wells in the cargo hold of NO96 LNG carriers, thereby solving the technical problems of large residual liquid volume and low operational economy in the cargo hold of NO96 LNG carriers.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution: A method for installing a pump well in the cargo hold of an NO96 type LNG carrier, wherein the lower surface of the pump well is provided with a limiting groove, and the periphery of the pump well is provided with outwardly extending lower and upper wing plates, which are arranged parallel to each other. The height difference between the lower and upper wing plates is equal to the height difference between the primary and secondary Invar membranes of the cargo hold containment system. Both the upper and lower wing plates are perpendicular to the axis of the pump well and are symmetrically arranged about the axis of the pump well. The installation method includes the following steps: S1. Mark the positions of the studs and support beams on the hull surface at the bottom of the cargo hold. Weld the studs to the hull surface according to the markings. The studs are used to fix the pump well and support beams. S2. After the leveling wedges around the pump well installation location are installed, determine the thickness of the resin and support beam and the theoretical installation height of the pump well based on the height of the leveling wedges around the pump well, so that the height of the lower wing plate after installation is the same as the height of the secondary Invar membrane in the cargo hold enclosure system, and the height of the upper wing plate is the same as the height of the primary Invar membrane in the cargo hold enclosure system. S3. Fix multiple clamps around the designed location of the pump well. The clamps temporarily fix the pump well by supporting the lower wing plate so that the pump well reaches the theoretical installation height and position. S4. Lay multiple resin sheets on the surface of the hull, place support beams on the upper surface of the resin, and bond the upper surface of the resin to the lower surface of the support beams. The gaps between the resin sheets and the gaps between the support beams together form the installation space. S5. Hoisting the pump well: The pump well is temporarily fixed by the clamps fixed in S3, so that the pump well is placed on the support beam to achieve the theoretical installation height and position of the support beam. The limiting groove is placed in the installation space. After the resin is deformed by pressure, it enters the curing stage. After the resin curing is completed, the clamps are separated from the hull surface. S6. According to the position of the limiting groove, make the upper side of the stop post extend into the limiting groove, spot weld the positioning stop post to the hull surface, and make sure that the top of the stop post is a certain distance from the bottom of the pump well. Remove the pump well and completely weld the stop post to the hull surface. S7. Reset the pump well and place it back on the support beam. The pump well is fixed to the hull surface by studs. The anti-lifting component is installed on the upper end of the studs. The lower wing plate is welded and fixed to the secondary Invar membrane in the cargo hold containment system, and the upper wing plate is welded and fixed to the main Invar membrane in the cargo hold containment system.

[0006] In one implementation, in S3, kraft paper is laid on the surface of the hull before the resin is laid.

[0007] In one embodiment, the studs include high studs and low studs. The high studs are used to fix the pump well, and the low studs are used to fix the support beam. Low studs are symmetrically arranged on both sides of each high stud. The pump well is provided with multiple mounting holes, and the support beam is provided with multiple mounting holes. In S7, the high studs pass through the mounting holes of the support beam and the mounting holes of the pump well in sequence, and the low studs pass through the mounting holes of the support beam. After the high studs and low studs pass through the mounting holes, anti-lifting components are installed on the upper side of the high studs and low studs respectively.

[0008] In one embodiment, the anti-lifting assembly includes a nut, a washer, and a gasket. In S7, the step of installing the anti-lifting assembly on the upper side of the high stud and the low stud respectively is as follows: the gasket, the washer, and the nut are sequentially fitted onto the stud, and finally the nut is welded onto the bolt.

[0009] In one embodiment, the support beam is made of plywood, and a stainless steel plate is fixed to the upper surface of the plywood by rivets.

[0010] In one embodiment, the upper end of the clamp is provided with a height adjusting bolt and a horizontal adjusting bolt. The height adjusting bolt is vertically positioned and can move up and down, while the horizontal adjusting bolt is horizontally positioned and can move laterally. S3 specifically includes: multiple clamps are symmetrically arranged and fixed on the hull surface about the theoretical installation position of the pump well; the lower wing plate is placed on the top of the clamp; the height adjusting bolt in the clamp is moved up and down until the pump well is at the installation height; and then the horizontal adjusting bolts of the multiple clamps are moved left and right until the center of the pump well is at the center of the installation position.

[0011] In one embodiment, multiple limiting grooves are symmetrically arranged about the center of the pump well and fixed on the lower surface of the pump well. The limiting grooves are U-shaped grooves parallel to the bottom surface of the pump well, and the openings of the U-shaped grooves face outwards.

[0012] Compared with the prior art, this application has at least the following beneficial effects: The pump well installation method described in this application is applicable to the cargo tank of an LNG carrier with a NO96 containment system. The pump well is fixed by studs, which are welded to the hull along markings. Some studs fix the support beam to the hull, while others fix the pump well to the support beam. During installation, clamps are used to adjust the pump well's vertical and horizontal movement until the required installation accuracy is achieved. Resin is pre-applied to the bottom of the support beam; during pump well installation, the resin is compressed, forming an effective support surface. After the resin cures, the clamps are removed. After the pump well is initially installed in place, a stop post is spot-welded to lock its position. The pump well is then removed, and the stop post is fully welded. After full welding, the pump well is reset, thus precisely controlling the gap between the stop post and the pump well's limiting groove. This installation method not only enables precise installation of pump wells within the cargo tank of an LNG carrier with a NO96 containment system, reducing residual liquid volume and improving operational economy, but also ensures the integrity and continuity of the Invar steel membrane within the cargo tank of an LNG carrier with a NO96 containment system. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of fixing studs on the surface of the hull in an embodiment of this application; Figure 2 This is a schematic diagram of a clamp fixing fixture on the hull surface in an embodiment of this application; Figure 3 This is a schematic diagram of resin being laid on the surface of the hull in an embodiment of this application; Figure 4 This is a schematic diagram of a support beam placed on the resin surface in an embodiment of this application; Figure 5 This is a schematic diagram of the temporary fixed pump well on the surface of the support beam in an embodiment of this application; Figure 6This is a schematic diagram of the spot-welded stop column in an embodiment of this application; Figure 7 This is a schematic diagram of the fixed stop post in an embodiment of this application; Figure 8 This is a schematic diagram of the pump well installation in an embodiment of this application.

[0014] Reference numerals: 01, hull surface; 1, stud; 101, high stud; 102, low stud; 2, clamp; 201, height adjusting bolt; 202, level adjusting bolt; 3, resin; 4, support beam; 5, pump well; 501, limiting groove; 502, lower wing plate; 503, upper wing plate; 6, stop post. Detailed Implementation

[0015] To make the objectives, technical solutions, and advantages of this invention clearer, the invention is described below with reference to specific embodiments shown in the accompanying drawings. However, it should be understood that these descriptions are merely exemplary and not intended to limit the scope of the invention. Furthermore, descriptions of well-known structures and technologies are omitted in the following description to avoid unnecessarily obscuring the concept of the invention.

[0016] The terminology used in this disclosure is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. The singular forms “a,” “the,” and “the” as used in this disclosure and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used herein refers to and includes any and all possible combinations of one or more of the associated listed items.

[0017] 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 construed as indicating or implying relative importance. These terms are used only to distinguish information of the same type from one another. For example, without departing from the scope of this disclosure, first information may also be referred to as second information, and similarly, second information may also be referred to as first information. Depending on the context, the word "if" as used herein may be interpreted as "when," "when," or "in response to determination."

[0018] In the description of this invention, unless otherwise specified and limited, it should be noted that the terms "installation", "connection" and "linking" should be interpreted broadly. For example, they can refer to mechanical connection or internal connection between two components. They can be direct connection or indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms according to the specific circumstances.

[0019] To better understand the technical solution of the present invention, the present invention will be described in detail below with reference to the accompanying drawings.

[0020] This embodiment provides a method for installing a pump well inside the cargo hold of a NO96 type LNG carrier, such as... Figure 1-7 As shown, a limiting groove 501 is provided on the lower surface of the pump well 5. A lower wing plate 502 and an upper wing plate 503 protrude outwards from the periphery of the pump well 5. The lower wing plate 502 and the upper wing plate 503 are arranged parallel to each other. The height difference between the lower wing plate 502 and the upper wing plate 503 is equal to the height difference between the primary and secondary Invar membranes of the cargo hold containment system. Both the upper wing plate 502 and the lower wing plate 503 are perpendicular to the axis of the pump well 5 and are symmetrically arranged about the axis of the pump well 5. The installation method includes the following steps: S1. Mark the installation positions of stud 1 and support beam 4 on the hull surface 01 at the bottom of the cargo hold. Weld stud 1 to the hull surface 01 according to the markings. Stud 1 is used to fix pump well 5 and support beam 4. S2. After the leveling wedges around the pump well installation location are installed, determine the thickness of resin 3, support beam 4 and the theoretical installation height of pump well 5 based on the height of the leveling wedges around the pump well, so that the height of the lower wing plate 502 after installation is the same as the height of the secondary Invar membrane in the cargo hold enclosure system, and the height of the upper wing plate 502 is the same as the height of the primary Invar membrane in the cargo hold enclosure system. S3. Fix multiple clamps 2 around the designed location of the pump well. The clamps 2 temporarily fix the pump well 5 by supporting the lower wing plate 502 so that the pump well 5 reaches the theoretical installation height and installation position. S4. Multiple resin blocks 3 are laid on the surface 01 of the hull. Support beams 4 are placed on the upper surface of the resin blocks 3. The upper surface of the resin blocks 3 is bonded to the lower surface of the support beams 4. The gaps between the resin blocks 3 and the gaps between the support beams 3 together form the installation space. S5. Hoist the pump well. Fix the clamp 2 to temporarily fix the pump well 5 through S3, so that the pump well 5 is placed on the support beam 4 to reach the theoretical installation height of the support beam 4. The limiting groove 501 is placed in the installation space. After the resin 3 is deformed by pressure, it enters the curing stage. After the resin 3 is cured, the clamp 3 is separated from the hull surface 01. S6. According to the position of the limiting groove 501, make the upper side of the stop post 6 extend into the limiting groove 501, spot weld the positioning stop post 6 to the hull surface 01, the top of the stop post 6 is a certain distance from the bottom of the pump well 5, remove the pump well 5, and completely weld the stop post 6 to the hull surface 01. S7. Reset the pump well 5 and place the pump well back on the support beam 4. The pump well 5 is fixed to the hull surface by studs 1. An anti-lifting component is installed at the upper end of the studs 1. The lower wing plate 502 is welded and fixed to the secondary Invar membrane in the cargo hold containment system, and the upper wing plate 502 is welded and fixed to the main Invar membrane in the cargo hold containment system.

[0021] In this embodiment, before laying the resin 3 in S3, kraft paper is first laid on the hull surface 01, and then the resin 3 is laid. The kraft paper prevents the resin from sticking to the hull plate, ensuring that the pump well can achieve a small amount of movement in the horizontal plane during use.

[0022] like Figure 1 As shown, the stud 1 includes a high stud 101 and a low stud 102. The high stud 101 is used to fix the pump well 5, and the low stud 102 is used to fix the support beam 4. Low studs 102 are symmetrically arranged on both sides of each high stud 101. Multiple mounting holes are provided on the pump well 5 and the support beam 4. In step S7, the high stud 101 passes through the mounting holes of the support beam 4 and the pump well 5 in sequence, and the low stud 102 passes through the mounting holes of the support beam 4. After the high stud 101 and low stud 102 pass through the mounting holes, anti-lifting components are installed on the upper sides of the high stud 101 and low stud 102 respectively. The anti-lifting components include a nut, a washer, and a gasket. In step S7, the gasket, washer, and nut are sequentially fitted onto the stud 1, and finally, the nut is welded to the stud. The gasket in this application is made of polytetrafluoroethylene (PTFE). By installing anti-lift components, the pump well can not only be fixed to the hull surface, but also prevented from lifting.

[0023] The support beam 4 is made of plywood. To ensure the strength of the support beam 4, a stainless steel plate is fixed to the upper surface of the plywood with rivets.

[0024] The upper end of the clamp 2 is provided with a height adjustment bolt 201 and a horizontal adjustment bolt 202. The height adjustment bolt 201 is set vertically and can move up and down. The horizontal adjustment bolt 202 is set horizontally and can move horizontally. S3 specifically includes: multiple clamps 2 are symmetrically set about the theoretical installation position of the pump well 5 and fixed on the hull surface 01. The lower wing plate 502 is placed on the top of the clamp. The height adjustment bolt 201 in the clamp 2 is moved up and down until the pump well 5 is at the installation height. Then the horizontal adjustment bolts 202 of the multiple clamps are moved left and right until the center of the pump well 5 is at the center of the installation position.

[0025] In this embodiment, multiple limiting grooves 501 are symmetrically arranged about the center of the pump well 5 and fixed on the lower surface of the pump well 5. The limiting grooves 501 are U-shaped grooves parallel to the bottom surface of the pump well 5, with the openings of the U-shaped grooves facing outwards to facilitate the placement of the stop post 6. The cooperation between the stop post 6 and the limiting grooves 501 can restrict the movement of the pump well 5 in the horizontal plane.

[0026] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them; although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications can still be made to the specific implementation of the invention or equivalent substitutions can be made to some technical features without departing from the spirit of the technical solutions of the present invention, and all such modifications and substitutions should be covered within the scope of the technical solutions claimed in the present invention.

Claims

1. A method for installing a pump well in the cargo hold of a NO96 type LNG carrier, characterized in that, The lower surface of the pump well is provided with a limiting groove. The periphery of the pump well is provided with outwardly extending lower and upper wing plates, which are arranged parallel to each other. The height difference between the lower and upper wing plates is equal to the height difference between the primary and secondary Invar membrane layers of the cargo hold containment system. Both the upper and lower wing plates are perpendicular to the axis of the pump well and are symmetrically arranged about the axis of the pump well. The installation method includes the following steps: S1. Mark the positions of the studs and support beams on the hull surface at the bottom of the cargo hold. Weld the studs to the hull surface according to the markings. The studs are used to fix the pump well and support beams. S2. After the leveling wedges around the pump well installation location are installed, determine the thickness of the resin and support beam and the theoretical installation height of the pump well based on the height of the leveling wedges around the pump well, so that the height of the lower wing plate after installation is the same as the height of the secondary Invar membrane in the cargo hold enclosure system, and the height of the upper wing plate is the same as the height of the primary Invar membrane in the cargo hold enclosure system. S3. Fix multiple clamps around the designed location of the pump well. The clamps temporarily fix the pump well by supporting the lower wing plate so that the pump well reaches the theoretical installation height and position. S4. Lay multiple resin sheets on the surface of the hull, place support beams on the upper surface of the resin, and bond the upper surface of the resin to the lower surface of the support beams. The gaps between the resin sheets and the gaps between the support beams together form the installation space. S5. Hoisting the pump well: The pump well is temporarily fixed by the clamps fixed in S3, so that the pump well is placed on the support beam to achieve the theoretical installation height and position of the support beam. The limiting groove is located in the installation space. After the resin is deformed by pressure, it enters the curing stage. After the resin curing is completed, the clamps are separated from the hull surface. S6. According to the position of the limiting groove, install the stop post in the limiting groove, spot weld the positioning stop post to the hull surface, the top of the stop post is a certain distance from the bottom of the pump well, remove the pump well, and completely weld the stop post to the hull surface. S7. Reset the pump well and place it back on the support beam. The pump well is fixed to the hull surface by studs. The anti-lifting component is installed on the upper end of the studs. The lower wing plate is welded and fixed to the secondary Invar membrane in the cargo hold containment system, and the upper wing plate is welded and fixed to the main Invar membrane in the cargo hold containment system.

2. The pump well installation method according to claim 1, characterized in that, In S3, before laying the resin, kraft paper is first laid on the surface of the hull, and then the resin is laid.

3. The pump well installation method according to claim 1, characterized in that, The studs include high studs and low studs. The high studs are used to fix the pump well, and the low studs are used to fix the support beam. Low studs are symmetrically arranged on both sides of each high stud. The pump well is provided with multiple mounting holes, and the support beam is provided with multiple mounting holes. In S7, the high studs pass through the mounting holes of the support beam and the mounting holes of the pump well in sequence, and the low studs pass through the mounting holes of the support beam. After the high studs and low studs pass through the mounting holes, anti-lifting components are installed on the upper side of the high studs and low studs respectively.

4. The pump well installation method according to claim 3, characterized in that, The anti-lifting assembly includes a nut, a washer, and a gasket. In S7, the steps for installing the anti-lifting assembly on the upper side of the high stud and the low stud are as follows: the gasket, the washer, and the nut are sequentially fitted onto the stud, and finally the nut is welded onto the bolt.

5. The pump well installation method according to claim 1, characterized in that, The support beam is made of plywood, and a stainless steel plate is fixed to the upper surface of the plywood by rivets.

6. The pump well installation method according to claim 1, characterized in that, The upper end of the clamp is provided with a height adjustment bolt and a horizontal adjustment bolt. The height adjustment bolt is set vertically and can move up and down. The horizontal adjustment bolt is set horizontally and can move horizontally. S3 specifically includes: multiple clamps are symmetrically set about the theoretical installation position of the pump well and fixed on the surface of the hull. The lower wing plate is placed on the top of the clamp. The height adjustment bolt in the clamp is moved up and down until the pump well is at the installation height. Then the horizontal adjustment bolts of the multiple clamps are moved left and right until the center of the pump well is at the center of the installation position.

7. The pump well installation method according to claim 1, characterized in that, Multiple limiting grooves are symmetrically arranged about the center of the pump well and fixed on the lower surface of the pump well. The limiting grooves are U-shaped grooves parallel to the bottom surface of the pump well, and the openings of the U-shaped grooves face outwards.

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