Low temperature resistant sealing film for covering insulating material, tank and manufacturing method

Abstract

This invention provides a low-temperature resistant sealing film, a storage tank, and a manufacturing method for covering insulating materials. The sealing film includes at least one film plate. Each template includes multiple quadrilateral plate units welded and fixed by a sealing welding method. Each plate unit includes an undulating region and a planar region. The undulating region has arc-shaped strip-shaped main protrusions that are connected tangentially. Each plate unit has at least four main protrusions that are symmetrically arranged about the center of the plate unit and perpendicular to the centerline of the plate unit. Each arc-shaped main protrusion has its inner corner point of the corresponding plate unit as its center. Each main protrusion is hollow, and the cross-section of each main protrusion includes a top arc segment and a connecting arc segment. The curvature of the top arc segment is continuous. One end of the connecting arc segment is tangentially connected to one end of the top arc segment, and the other end of the connecting arc segment is tangentially connected to the planar region.

Description

Technical Field

[0001] This invention relates to the field of sealed and insulated storage tanks for storing and transporting cryogenic liquefied gases, and in particular to a sealing membrane, a storage tank, and a method for manufacturing and welding the sealing membrane for use in sealed and insulated storage tanks on cryogenic liquid / cryoliquefied gas transport ships. Background Technology

[0002] Chinese patent CN101959752B discloses a corrugated diaphragm for LNG carrier cargo tanks and a reinforcing member for the corresponding corrugations. The corrugated diaphragm includes a corrugated section and a flat section. The longitudinal girder of the corrugated section is interlaced, and the longitudinal corrugations and transverse corrugations have different shapes and heights. Corrugated knots are formed at the intersection of the corrugations due to compression. The corrugated diaphragm is in direct contact with liquefied natural gas, and sudden temperature changes can cause large displacement stress in the structure.

[0003] When this type of membrane is actually applied to the cargo tanks of LNG carriers, environmental conditions such as sea state or wind during navigation can cause sloshing and movement of the liquid within the tank. Typically, under the influence of irregular waves, the free surface of the liquid fluctuates, causing nonlinear and random movement of the liquid within the tank. This sloshing liquid inevitably generates sloshing impacts on the tank, and the impact stress generates peak loads based on the amplitude and frequency of the waves. These peak impact stresses can easily cause plastic deformation or even damage to the sealing membrane, which is already deformed by temperature stress. When the sealing membrane is damaged, it loses its function, ultimately potentially leading to the leakage of liquefied gas.

[0004] When the sealing membrane is installed on the inner wall of the insulating tank in the cargo tank of an LNG ship, it needs to withstand the displacement caused by temperature changes, avoid plastic deformation, and better withstand the liquid impact during liquid sloshing, effectively resisting impact deformation, preventing the sealing membrane or even the insulation layer from cracking and failing, and ensuring the sealing performance of the cryogenic storage tank. Summary of the Invention

[0005] In view of the above-mentioned problems existing in the prior art, the present invention provides a cryogenic sealing film for covering insulating materials, a storage tank, and a method for manufacturing the sealing film. It can withstand the displacement caused by temperature changes in the cargo tank of an LNG ship during loading and unloading of liquefied natural gas, avoid excessive plastic deformation, and better withstand liquid impact during liquid sloshing, effectively resisting impact deformation, preventing the sealing film or even the insulation layer from cracking and failing, and ensuring the sealing performance of the cryogenic storage tank.

[0006] This invention provides a low-temperature resistant sealing film for covering insulating materials. The sealing film includes at least one film plate, and each of the at least one film plate includes multiple plate units welded and fixed by a sealing welding method. The plate units are arranged in a regular quadrilateral shape and include undulating areas and planar areas.

[0007] The undulating area is provided with arc-shaped strips that are connected tangentially. Each plate unit is provided with at least four main protrusions symmetrically arranged about a centerline that passes through the center of the plate unit and is perpendicular to the plane area of ​​the plate unit. Each arc-shaped main protrusion is centered on the corner end of the plate unit corresponding to its inner side. After two adjacent plate units are welded and fixed, the main protrusions on the adjacent sides of the two adjacent plate units are joined together.

[0008] Each of the main protrusions is hollow, and the cross-section of each main protrusion includes a top arc segment and a connecting arc segment. The curvature of the top arc segment is continuous. One end of the connecting arc segment is tangentially connected to one end of the top arc segment, and the other end of the connecting arc segment is tangentially connected to the planar region.

[0009] In some embodiments of the present invention, the undulating area is further provided with secondary protrusions that are concentrically arranged with each main protrusion. The secondary protrusions are symmetrically arranged about the center and are all arranged in arc-shaped strips. After two adjacent plate units are welded and fixed, the secondary protrusions on the adjacent sides of the two adjacent plate units are joined together.

[0010] The height of the secondary protrusion is not greater than the height of the main protrusion, and there is at least a distance between the main protrusion and the secondary protrusion that is twice the width of the main protrusion.

[0011] In some embodiments of the present invention, each of the sub-protrusions is hollow and the cross-section of the sub-protrusion is arc-shaped;

[0012] The spacing between two adjacent sub-protrusions is at least twice the width of the sub-protrusion.

[0013] In some embodiments of the present invention, the height dimension of the cross-section of the main protrusion is represented by H, and then 40mm≤H≤60mm;

[0014] The top arc segment includes a top arc with a radius of R1 and a transition arc connected tangentially to the top arc and denoted by R2, wherein R1 is less than R2.

[0015] If the arc segment of the connecting part is a circular arc and is represented by R3, then:

[0016] 1≤R1:R3≤2;

[0017] 5.5≤R2:R3≤10;

[0018] 1 < R2: H ≤ 1.5.

[0019] In some embodiments of the present invention, the height dimension of the cross-section of the main protrusion is represented by H, and then 36mm≤H≤48mm;

[0020] The top arc segment satisfies the following formula to represent a parabola, specifically:

[0021]

[0022] The connecting arc segment is a circular arc and tangent to the parabola, with the arc radius R3 satisfying the following:

[0023] 4≤H:R3≤8.

[0024] In some embodiments of the present invention, the height dimension of the cross-section of the main protrusion is represented by H, and then 40mm≤H≤50mm;

[0025] The top arc segment satisfies the following formula to represent a parabola, specifically:

[0026] And 5 / 8 ≤ a / H ≤ 1;

[0027] The connecting arc segment is a circular arc with a radius of R3, which is tangent to the ellipse in the first and second quadrants and satisfies 0.15≤R3:H≤0.25.

[0028] In some embodiments of the present invention, the plate unit is made of stainless steel, aluminum alloy or high manganese steel with a yield strength between 170MPa and 500MPa and a thickness between 2 and 4mm. During the welding process, adjacent plate units are welded in the same direction.

[0029] In some embodiments of the present invention, each of the membrane plates has a length of at least 0.6m in both the transverse and longitudinal directions.

[0030] This invention also provides a storage tank employing a low-temperature resistant sealing film for covering insulating material as described in the above embodiments, the storage tank comprising:

[0031] The tank wall, which encloses the internal space of the storage tank, comes into contact with the cryogenic liquefied gas.

[0032] An insulating structure is attached to the tank wall, and the low-temperature resistant sealing film is disposed on the surface of the insulating structure away from the tank wall.

[0033] This invention also provides a method for manufacturing a low-temperature resistant sealing film for covering insulating materials as described in the above embodiments, the method comprising:

[0034] Step 1: Based on the structural design drawings of the low-temperature resistant sealing film used to cover the insulating material as described in the above embodiment, design the undulating area mold, and combine the rebound prediction made on the elasticity of the material to make a suitable undulating area mold.

[0035] Step 2: Based on the predicted reduction in sheet thickness and springback of shape after stamping, select a metal sheet of appropriate thickness and cut it into sheet units with a set allowance. Then, put the sheet units into a press for processing. The press and the mold for the undulating area are used for stamping and forming to obtain sheet units with the convex shape corresponding to the undulating area.

[0036] Step 3: Based on the size of the insulation module corresponding to the insulation material to be covered, arrange the plate units in the same direction to form a rectangular plate that matches the size of the insulation module, and then weld the plate units together to form a membrane plate.

[0037] Step 4: Place the membrane plate on the insulating layer formed by the insulating module, and weld and fix the membrane plates one by one by continuous overlapping welding according to the principle of aligning the cross-sectional shapes of the undulating areas of adjacent membrane plates to form a complete sealing membrane.

[0038] Compared with the prior art, the beneficial effects of the low-temperature resistant sealing film, storage tank, and manufacturing method for covering insulating materials provided by the embodiments of the present invention are as follows: the main protrusions in the undulating region are arranged tangentially and intersectingly on the planar region, and the regular distribution greatly reduces the proportion of the planar region. At the same time, the deformation and compression in the horizontal plane caused by temperature changes are greatly reduced, and the approximately U-shaped elastic shape of the protrusions also provides a large deformation margin. Furthermore, the seamless distribution of the main protrusions in the undulating region, which are tangentially connected, combined with the relatively dense arrangement of the secondary protrusions in the planar region, evenly disperses the swaying impact load, thereby effectively avoiding damage to the sealing film and ensuring the sealing performance of the film. Attached Figure Description

[0039] Figure 1 This is an axonometric view of a structure of a low-temperature resistant sealing film for covering insulating materials, provided in an embodiment of the present invention.

[0040] Figure 2 This is an axonometric view of a plate unit for covering an insulating material with a low-temperature resistant sealing film, as provided in an embodiment of the present invention.

[0041] Figure 3 An axonometric view of another structure of a low-temperature resistant sealing film for covering insulating material, provided in an embodiment of the present invention.

[0042] Figure 4This is an axonometric view of another structure of the plate unit for covering the insulating material with a low-temperature resistant sealing film provided in an embodiment of the present invention.

[0043] Figure 5 This is a schematic cross-sectional view of the main protrusion of the undulating region of the low-temperature resistant sealing film used to cover insulating material, provided in an embodiment of the present invention.

[0044] Figure 6 A schematic diagram of the first line shape of the main protrusion cross-section of the undulating region of the low-temperature resistant sealing film for covering insulating material provided in an embodiment of the present invention;

[0045] Figure 7 A schematic diagram of a second line shape of the main protrusion cross-section of the undulating region of the low-temperature resistant sealing film for covering insulating material, provided in an embodiment of the present invention;

[0046] Figure 8 A schematic diagram of the third line shape of the main protrusion cross-section of the undulating region of the low-temperature resistant sealing film for covering insulating material provided in an embodiment of the present invention;

[0047] Figure 9 This is a cross-sectional schematic diagram of a storage tank installed with a low-temperature resistant sealing membrane for covering insulating material, as provided in an embodiment of the present invention.

[0048] Figure Labels

[0049] 1. Sealing membrane; 2. Plate unit; 3. Main protrusion; 4. Secondary protrusion; 5. Planar area;

[0050] 6. Cross section; 7. Top arc; 8. Transition arc; 9. Connecting arc segment; 10. Insulation structure. Detailed Implementation

[0051] To enable those skilled in the art 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 and specific embodiments.

[0052] Various embodiments and features of this application are described herein with reference to the accompanying drawings.

[0053] These and other features of this application will become apparent from the following description of preferred forms of embodiments given as non-limiting examples, with reference to the accompanying drawings.

[0054] It should also be understood that although this application has been described with reference to some specific examples, those skilled in the art can certainly implement many other equivalent forms of this application, which have the features described in the claims and are therefore all within the scope of protection defined herein.

[0055] The above and other aspects, features and advantages of this application will become more apparent when taken in conjunction with the accompanying drawings and in view of the following detailed description.

[0056] Specific embodiments of this application are described below with reference to the accompanying drawings; however, it should be understood that the claimed embodiments are merely examples of this application, which can be implemented in various ways. Well-known and / or repeated functions and structures are not described in detail to ascertain the true intent based on the user's historical operations, and to avoid unnecessary or redundant details that would obscure this application. Therefore, the specific structural and functional details claimed herein are not intended to be limiting, but merely serve as the basis and representative basis for the claims to teach those skilled in the art to use this application in various ways with substantially any suitable detailed structure.

[0057] This specification may use the phrases “in one embodiment,” “in another embodiment,” “in yet another embodiment,” or “in other embodiments,” all of which may refer to one or more of the same or different embodiments according to this application.

[0058] This invention provides a cryogenic sealing film for covering insulating materials, applicable to cryogenic liquid transport ships / cryoliquefied gas transport ships. The transport ship has a sealed and insulated storage tank structure for storing cryogenic liquids or cryogenic liquefied gases, which can be used to transport liquefied natural gas at temperatures as low as -163°C. Furthermore, the liquefied gas storage tank can be installed not only on moving structures such as the ship's hull, but also on fixed land-based storage tank structures, or on floating or aquatic structures at sea. Figures 1 to 9 As shown, the low-temperature resistant sealing membrane 1 includes at least one membrane plate. Each template in the at least one module includes multiple plate units 2 welded and fixed by a sealing welding method. The plate unit 2 is arranged in a regular quadrilateral shape and includes an undulating region and a planar region 5.

[0059] The undulating area is provided with main protrusions 3 arranged in arc shape and connected tangentially. Each plate unit 2 is provided with at least four main protrusions 3 symmetrically arranged about the center line that passes through the center of the plate unit 2 and is perpendicular to the plane area 5 of the plate unit 2. Each arc-shaped main protrusion 3 takes the corner end point of the corresponding plate unit 2 on its inner side as the center. After two adjacent plate units 2 are welded and fixed, the main protrusions 3 on the adjacent sides of the two adjacent plate units 2 are joined together.

[0060] Each of the main protrusions 3 is hollow, and the cross-section 6 of each main protrusion 3 includes a top arc segment and a connecting arc segment 9. The curvature of the top arc segment is continuous. One end of the connecting arc segment 9 is connected tangentially to one end of the top arc segment, and the other end of the connecting arc segment 9 is connected tangentially to the planar region 5. The tangent point of the main protrusion 3 transitions with a smooth curvature. The cross-section obtained by cutting perpendicularly to the plane along the tangent direction has a consistent curvature in the transition area arc between the cross-sections of the two main protrusions 3.

[0061] That is, in the above embodiment, when four plate units 2 are spliced ​​together to form a regular quadrilateral, the main protrusions 3 on the four plate units 2 form a ring with the corners of the four plate units 2 as the center, and a circular planar region 5 is generated around it. The main protrusion 3 is the straight line normal to the center of the planar region 5 as the axis, and the symmetry plane of the cross section 6 of the main protrusion 3 is kept perpendicular to the plane corresponding to the planar region 5. The cross section 6 of the main protrusion 3 and the axis are placed in the same plane, and the rotating graphic structure is obtained by rotating 360 degrees with the axis as the center of rotation. Figure 1 As shown, it illustrates the sealing membrane 1 and its boundary.

[0062] In this embodiment, the plate unit 2 can have four symmetrical planes. After rotating 90 degrees along the centerline, the shape of the plate unit 2 remains completely identical. The membrane plate is welded from the plate unit 2 using a sealed welding method. Due to the symmetry of the plate unit 2, it is only necessary to arrange the sides symmetrically for welding.

[0063] In some embodiments of the present invention, the undulating region is further provided with secondary protrusions 4, which are concentrically arranged with each main protrusion 3 and formed by a single arc-shaped strip protrusion. The secondary protrusions 4 are symmetrically arranged about the center and are all arc-shaped strips. After two adjacent plate units 2 are welded and fixed, the secondary protrusions 4 on the adjacent sides of the two adjacent plate units 2 are joined together. At least four main protrusions 3 and four secondary protrusions 4 can be seen on any plate unit 2. The main protrusions 3 are composed of tangentially arranged arc-shaped strip protrusions. Each arc-shaped strip protrusion intersects and surrounds to form an approximately circular planar region 5, with the secondary protrusion 4 at the center of the planar region 5.

[0064] The height of the secondary protrusion 4 is not greater than the height of the main protrusion 3, and there is at least a distance between the main protrusion 3 and the secondary protrusion 4 that is twice the width of the main protrusion 3.

[0065] The width of the protrusion (including the width of the main protrusion 3 and the width of the secondary protrusion 4) refers to the distance between the tangent lines of the connecting areas (connecting arc segments 9) on both sides of the protrusion and the planar area 5.

[0066] like Figure 3 and Figure 4 As shown, it illustrates a sealing film 1, a plate unit 2 and its boundary having a secondary protrusion 4. Specifically, the secondary protrusion 4 is similar in shape to the main protrusion 3, consisting of a single arc-shaped distribution of long strip protrusions. The annular shape obtained by rotating the cross-section of the protrusion 360° with the center of the planar portion as the rotation center is used as the secondary protrusion 4.

[0067] In this embodiment, each of the secondary protrusions 4 is hollow, and the cross-section of the secondary protrusion 4 is arc-shaped; the distance between two adjacent secondary protrusions 4 is at least twice the width of the secondary protrusion 4. Specifically, the secondary protrusion 4 may have a similar cross-sectional shape to the main protrusion 3, and the annular shape obtained by rotating the cross-section of the secondary protrusion 4 360° with the center of the planar region 5 as the rotation center is used as the secondary protrusion 4.

[0068] In this embodiment, the plate unit 2 is made of stainless steel, aluminum alloy or high manganese steel with a yield strength between 170MPa and 500MPa and a thickness between 2 and 4mm. During the welding process, adjacent plate units 2 are welded in the same direction.

[0069] Furthermore, each of the membrane plates has a length of at least 0.6m in both the transverse and longitudinal directions, and the lengths of the longitudinal and transverse membrane plates are not the same.

[0070] In some embodiments of the present invention, such as Figure 6 As shown, the height dimension of the cross section 6 of the main protrusion 3 is represented by H, and then 40mm≤H≤60mm; the top arc segment includes a top arc 7 with a radius represented by R1 and a transition arc 8 connected to the top arc 7 in a tangential manner and represented by R2, wherein R1 is less than R2, and the top arc 7 and the transition arc 8 are internally tangent to each other;

[0071] The connecting arc segment 9 is an arc and is represented by R3. The connecting arc segment 9 is externally tangent to the transition arc 8. Therefore:

[0072] 1≤R1:R3≤2;

[0073] 5.5≤R2:R3≤10;

[0074] 1 < R2: H ≤ 1.5.

[0075] As an example, the height H of the cross section 6 of the main protrusion 3 is 41.58 mm, the radius R1 of the top arc 7 is 7.78 mm, the radius R2 of the transition arc 8 is 46.89 mm, and the radius R3 of the arc segment 9 of the connecting part is 5.06 mm.

[0076] In other embodiments of the invention, such as Figure 7 As shown, the height dimension of the cross section 6 of the main protrusion 3 is represented by H, and then 36mm≤H≤48mm;

[0077] The top arc segment satisfies the following formula to represent a parabola, specifically:

[0078]

[0079] The connecting arc segment 9 is a circular arc and tangent to the parabola, with the arc radius R3 satisfying the following:

[0080] 4≤H:R3≤8.

[0081] As an example, the height H of the cross section 6 of the main protrusion 3 is 48mm, and the radius of the arc of the connecting arc segment 9 is R3 = 6.41mm.

[0082] In other embodiments of the invention, such as Figure 8 As shown, the height dimension of the cross section 6 of the main protrusion 3 is represented by H, and then 40mm≤H≤50mm;

[0083] The top arc segment satisfies the following formula to represent a parabola, specifically:

[0084] And 5 / 8 ≤ a / H ≤ 1;

[0085] The connecting arc segment 9 is a circular arc with a radius of R3, which is tangent to the ellipse in the first and second quadrants and satisfies 0.15≤R3:H≤0.25.

[0086] As an example, the height H of the cross section 6 of the main protrusion 3 is 45mm, and the radius R3 of the arc segment 9 of the connecting part is 8.2mm.

[0087] As can be seen from the above technical solution, the low-temperature resistant sealing film for covering insulating materials provided in the above embodiments of the present invention has main protrusions in the undulating region arranged tangentially and intersectingly on the planar region 5. The regular distribution greatly reduces the proportion of the planar region 5. While the deformation and compression in the horizontal plane caused by temperature changes are greatly reduced, the approximately U-shaped elastic shape of the protrusions also provides a large deformation margin. Furthermore, the seamless distribution of the main protrusions 3 in the undulating region, which are tangentially connected, combined with the relatively dense arrangement of the secondary protrusions 4 in the planar region 5, evenly disperses the swaying impact load, thereby effectively avoiding damage to the sealing film 1 and ensuring the sealing performance of the film.

[0088] The aforementioned cryogenic sealing membrane used to cover insulating materials can be used in the cargo tanks of LNG carriers. The cargo tanks are cryogenic insulating storage tanks, which include a sealing membrane 1 and an insulating structure 10. The sealing membrane 1 is arranged on the insulating structure 10 and is formed by welding multiple membrane plates together by lap welding.

[0089] The aforementioned sealing membrane can also be installed on the inner surface of the insulating compartment of onshore storage tanks, for example, in storage tanks for onshore LNG or other floating structures on water, particularly liquefied gas land tanks, floating (production) storage units on or under water, etc. The liquefied gas itself inside the insulating tank can also serve as fuel reserves for structural operation.

[0090] Therefore, this embodiment of the invention also provides a storage tank employing the low-temperature resistant sealing film for covering insulating material provided in the above embodiments, such as... Figure 9 As shown, the storage tank includes: a tank wall that encloses the internal space of the storage tank and is in contact with the cryogenic liquefied gas; and an insulating structure 10 that is attached to the tank wall, wherein the cryogenic sealing film 1 is disposed on the surface of the insulating structure 10 away from the tank wall.

[0091] In the aforementioned storage tank, the regular distribution of undulating areas on the sealing membrane 1 greatly reduces the proportion of the planar area 5, thus significantly reducing deformation and compression in the horizontal plane caused by temperature changes. Furthermore, the tangential connection of the undulating areas and the seamless distribution of the protrusions effectively and evenly disperse and withstand the swaying impact load, thereby effectively preventing damage to the sealing membrane 1 and ensuring the membrane's sealing performance.

[0092] This invention also provides a method for manufacturing a low-temperature resistant sealing film for covering insulating materials as provided in the above embodiments. The method involves sequentially connecting metal plates divided into plate units 2 to form a film plate, and then welding the film plates together to form a sealing film 1. The method includes:

[0093] Step 1: Based on the structural design drawings of the low-temperature resistant sealing film 1 used to cover the insulating material provided in the above embodiment, design the undulating area mold, and combine the rebound prediction made on the elasticity of the material to make a suitable undulating area mold.

[0094] Step 2: Based on the predicted reduction in sheet thickness and springback of shape after stamping, select a metal sheet of appropriate thickness and cut it into sheet unit 2 with a set allowance. Then, put the sheet unit 2 into a press for processing. The sheet unit 2 is stamped and formed by the press and the mold for the undulating area to obtain the sheet unit 2 with the convex shape corresponding to the undulating area.

[0095] Step 3: Based on the size of the insulation module corresponding to the insulation material to be covered, arrange the plate units 2 in the same direction to form a rectangular plate that matches the size of the insulation module, and then weld and fix the plate units 2 by sealing welding to form a membrane plate.

[0096] Step 4: Place the membrane plate on the insulating layer formed by the insulating module, and weld and fix the membrane plates one by one by continuous lap welding according to the principle of aligning the cross-sectional shapes of the undulating areas of adjacent membrane plates to form a complete sealing membrane 1.

[0097] The low-temperature resistant sealing membrane 1 produced by the above method has main protrusions in the undulating region arranged tangentially and intersectingly on the planar region 5. The regular distribution greatly reduces the proportion of the planar region 5. While the deformation and compression in the horizontal plane caused by temperature changes are greatly reduced, the approximately U-shaped elastic shape of the protrusions also provides a large deformation margin. Furthermore, the seamless distribution of the main protrusions 3 in the undulating region, which are tangentially connected, combined with the relatively dense arrangement of the secondary protrusions 4 in the planar region 5, evenly disperses the swaying impact load, thereby effectively avoiding damage to the sealing membrane 1 and ensuring the sealing performance of the membrane.

[0098] The above embodiments are merely exemplary embodiments of the present invention and are not intended to limit the present invention. The scope of protection of the present invention is defined by the claims. Those skilled in the art can make various modifications or equivalent substitutions to the present invention within its spirit and scope of protection, and such modifications or equivalent substitutions should also be considered to fall within the scope of protection of the present invention.

Claims

1. A low-temperature resistant sealing film for covering insulating materials, characterized in that, The sealing membrane includes at least one membrane plate, each of which comprises multiple plate units welded and fixed by a sealing welding method. The plate units are arranged in a regular quadrilateral shape and include undulating regions and planar regions. The undulating area is provided with arc-shaped strips of main protrusions that are connected tangentially. Each plate unit has at least four main protrusions, which are symmetrically arranged about a centerline that passes through the center of the plate unit and is perpendicular to the plane area of ​​the plate unit. Each arc-shaped main protrusion has its inner corner point of the corresponding plate unit as the center. The plate unit has four symmetrical planes. After rotating 90 degrees along the centerline, the shape of the plate unit remains exactly the same. When two adjacent plate units are welded and fixed, they are welded in the same direction. After the two adjacent plate units are welded and fixed, the main protrusions on the adjacent sides of the two adjacent plate units are joined together. Each of the main protrusions is hollow, and the cross-section of each main protrusion includes a top arc segment and a connecting arc segment. The curvature of the top arc segment is continuous. One end of the connecting arc segment is tangentially connected to one end of the top arc segment, and the other end of the connecting arc segment is tangentially connected to the planar region. The tangent points of the main protrusions transition with a smooth curvature. The curvature of the arc in the transition region between the cross-sections of the two main protrusions is consistent when the cross-section is taken perpendicular to the plane along the tangent direction. When four plate units are spliced ​​together to form a regular quadrilateral, the corner endpoints where all four plate units are connected are taken as the center of the circle. A ring is formed through the main protrusions on the four plate units. At the same time, a circular planar area is generated around it. The main protrusion is the axis with the straight line normal to the center of the planar area as the axis. The symmetry plane of the cross-sectional curve of the main protrusion is kept perpendicular to the plane corresponding to the planar area. The cross-section of the main protrusion and the axis are placed in the same plane. The rotating graphic structure is obtained by rotating 360 degrees with the axis as the rotation center. The symmetry plane of the cross-sectional curve of the main protrusion is perpendicular to the planar area. The height of the cross-section of the main protrusion is greater than or equal to 36mm and less than or equal to 60mm.

2. The low-temperature resistant sealing film for covering insulating materials according to claim 1, characterized in that, The undulating area is also provided with secondary protrusions that are concentrically arranged with each main protrusion. The secondary protrusions are symmetrical about the center and are all arranged in arc-shaped strips. After two adjacent plate units are welded and fixed, the secondary protrusions on the adjacent sides of the two adjacent plate units are joined together. The height of the secondary protrusion is not greater than the height of the main protrusion, and there is at least a distance between the main protrusion and the secondary protrusion that is twice the width of the main protrusion.

3. The low-temperature resistant sealing film for covering insulating materials according to claim 2, characterized in that, Each of the sub-protrusions is hollow, and the cross-section of the sub-protrusion is arc-shaped; The spacing between two adjacent sub-protrusions is at least twice the width of the sub-protrusion.

4. The low-temperature resistant sealing film for covering insulating materials according to claim 1 or 2, characterized in that, The height dimension of the cross-section of the main protrusion is represented by H, and then 40mm≤H≤60mm; The top arc segment includes a top arc with a radius of R1 and a transition arc connected tangentially to the top arc and denoted by R2, wherein R1 is less than R2. If the arc segment of the connecting part is a circular arc and is represented by R3, then: 1≤R1:R3≤2; 5.5≤R2:R3≤10; 1 <R2:H≤1.5。 5. The low-temperature resistant sealing film for covering insulating materials according to claim 1 or 2, characterized in that, The height dimension of the cross-section of the main protrusion is represented by H, and then 36mm ≤ H ≤ 48mm; The top arc segment satisfies the following formula to represent a parabola, specifically: ( ) The connecting arc segment is a circular arc and tangent to the parabola, with the arc radius R3 satisfying the following: 4≤H:R3≤8.

6. The low-temperature resistant sealing film for covering insulating materials according to claim 1 or 2, characterized in that, The height dimension of the cross-section of the main protrusion is represented by H, and then 40mm ≤ H ≤ 50mm; The top arc segment satisfies the following formula to represent a parabola, specifically: ( ), and 5 / 8≤a / H≤1; The connecting arc segment is a circular arc with a radius of R3, which is tangent to the ellipse in the first and second quadrants and satisfies 0.15≤R3:H≤0.

25.

7. The low-temperature resistant sealing film for covering insulating materials according to claim 1, characterized in that, The plate units are made of stainless steel, aluminum alloy or high manganese steel with a yield strength between 170MPa and 500MPa and a thickness between 2 and 4mm. During the welding process, adjacent plate units are welded in the same direction.

8. The low-temperature resistant sealing film for covering insulating materials according to claim 1, characterized in that, Each of the membrane plates has a length of at least 0.6 m in both the transverse and longitudinal directions.

9. A storage tank employing a low-temperature resistant sealing membrane for covering insulating material as described in any one of claims 1 to 8, characterized in that, The storage tank includes: The tank wall, which encloses the internal space of the storage tank, comes into contact with the cryogenic liquefied gas. An insulating structure is attached to the tank wall, and the low-temperature resistant sealing film is disposed on the surface of the insulating structure away from the tank wall.

10. A method for manufacturing a low-temperature resistant sealing film for covering insulating materials as described in any one of claims 1 to 8, characterized in that, The method includes: Step 1: Based on the structural design drawings of the sealing film corresponding to the low-temperature resistant sealing film for covering insulating materials as described in any one of claims 1 to 8, design the undulating area mold, and combine the rebound prediction made on the elasticity of the material to be used to make a suitable undulating area mold. Step 2: Based on the predicted reduction in sheet thickness and springback of shape after stamping, select a metal sheet of appropriate thickness and cut it into sheet units with a set allowance. Then, put the sheet units into a press for processing. The press and the mold for the undulating area are used for stamping and forming to obtain sheet units with the convex shape corresponding to the undulating area. Step 3: Based on the size of the insulating film corresponding to the insulating material to be covered, arrange the adjacent plate units in the same direction to form a rectangular plate that matches the size of the insulating film. Then, weld the plate units together by sealing welding to form the film. Step 4: Place the membrane plate on the insulating layer formed by the insulating membrane plate, and weld and fix the membrane plates one by one by continuous overlapping welding according to the principle of aligning the cross-sectional shapes of the undulating areas of adjacent membrane plates to form a complete sealing membrane.

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