WO2022270672A1

WO2022270672A1 - Membrane for liquefied gas storage tank

Info

Publication number: WO2022270672A1
Application number: PCT/KR2021/009464
Authority: WO
Inventors: 오병택; 윤용근; 양영철; 서흥석; 진교국; 한해철; 임기호
Original assignee: 한국가스공사
Priority date: 2021-06-24
Filing date: 2021-07-22
Publication date: 2022-12-29
Also published as: KR20230000308A

Abstract

The present invention relates to a membrane having a plurality of corrugations for forming a sealing wall of a liquefied gas storage tank, wherein the plurality of corrugations comprise: a pair of side pleats spaced apart from each other in one direction to be disposed in parallel; and a pair of center pleats disposed opposite to each other between the pair of side pleats, and the pair of side pleats and the pair of center pleats have different sizes applied thereto.

Description

Membrane for liquefied gas storage tank

The present invention relates to a membrane for a liquefied gas storage tank that forms a sealing wall of a liquefied gas storage tank, and more particularly, reduces the risk of fatigue failure by reducing plastic strain due to cryogenic liquefied gas, It relates to a membrane for a liquefied gas storage tank capable of improving productivity and a manufacturing method of the membrane.

Due to the recent strengthening of environmental pollution regulation standards for ships, interest in eco-friendly and highly efficient liquefied gas fuels such as liquefied natural gas (LNG) or liquefied petroleum gas (LPG) this is increasing

Liquefied natural gas is obtained by cooling and liquefying methane obtained by refining natural gas collected from gas fields. .

In particular, liquefied natural gas (hereinafter referred to as 'LNG') is obtained by cooling natural gas to an extremely low temperature (about -163 ° C), and its volume is reduced to about 1/600 of that of gaseous natural gas, so it is safe to use the sea. It is very suitable for transport over long distances.

Liquefied gas is transported in a gaseous state through onshore or offshore gas pipelines, or transported in a liquid state to a distant consumer while stored on a transport ship.

A liquefied gas carrier for loading and unloading liquefied gas such as LNG by sea and loading and unloading liquefied gas to a place on land, or a liquefied gas carrier carrying LNG and navigating the sea and arriving at a place on land, regasifying stored LNG and unloading it in the form of natural gas A liquefied gas storage tank (commonly referred to as a 'cargo hold') that can withstand the cryogenic temperature of LNG is provided in an LNG RV (Regasification Vessel)

In addition, LNG FPSO (Floating, Production, Storage and Offloading) used to liquefy and store produced natural gas directly at sea, and to transfer stored LNG to LNG carriers when necessary, and to store LNG unloaded from LNG carriers at sea. Liquefied gas storage tanks installed in LNG carriers or LNG RVs are also included in offshore structures such as LNG Floating Storage and Regasification Units (FSRUs) that vaporize LNG as needed and supply it to onshore consumers.

These liquefied gas storage tanks can be classified into a membrane type and an independent type depending on whether the cargo load directly acts on the insulation.

A typical membrane-type LNG storage tank includes a secondary insulation layer installed on the inner wall of the hull, a secondary sealing layer installed on the secondary insulation layer, a primary insulation layer installed on the secondary sealing layer, and a first insulation layer installed on the primary insulation layer. A primary sealing layer is included.

The insulation layer is to prevent the liquefied gas from being heated by preventing external heat from entering the storage tank, and the sealing layer is to prevent the liquefied gas from leaking out of the storage tank. Even if one sealing layer is damaged, the other The sealing structure of the cargo hold is composed of a double layer so that the sealing layer can prevent leakage of liquefied natural gas.

In order to install the insulation layer and the sealing layer of the liquefied gas storage tank, first, a plurality of secondary insulation panels are coupled on the inner wall of the hull, a secondary sealing wall is installed on the plurality of secondary insulation panels, and a secondary sealing wall is placed on the secondary sealing wall. It is manufactured through the process of installing the primary insulation panel and finally installing the primary sealing wall on the primary insulation panel.

The foregoing technical configuration is a background technology for helping understanding of the present invention, and does not mean the prior art widely known in the technical field to which the present invention belongs.

On the other hand, in the KC-1 type tank recently developed by Korea Gas Corporation, a plurality of insulation panels are combined on the inner wall of the hull to form one insulation layer, and then a secondary barrier is installed on the plurality of insulation panels. And, by installing a primary barrier on the secondary sealing wall, it is possible to have one heat insulating layer and two sealing walls.

1 is a plan view showing a part of a membrane for a liquefied gas storage tank according to the prior art, and FIG. 2 is a view showing the wrinkled membrane of FIG. 1 in a separated manner.

As shown in FIG. 1 , the sealing wall may be provided by connecting a plurality of membranes by welding.

As an example, the sealing wall may be provided to achieve a complete sealing state by attaching the wrinkled membrane 10 having the

wrinkles

11 and 13 and the flat plate membrane 30 having a flat surface by welding to form a certain pattern. .

As shown in FIG. 2, the

creases

11 and 13 are a pair of side pleats 11 formed in a straight line parallel to each other and a straight line at regular intervals between the pair of side pleats 11. It may include a pair of central wrinkles 13 disposed as.

Here, the pair of side wrinkles 11 and the pair of central wrinkles 13 may have the same size (or length) and shape.

That is, the membrane for a liquefied gas storage tank according to the prior art is formed so that four

wrinkles

11 and 13 having the same size and shape are alternately arranged on a metal plate, thereby shrinking and expanding due to cryogenic LNG. It is provided to absorb thermal stress that may occur.

Here, the stress may be concentrated and applied to the end of the central corrugated portion 13 protruding in the longitudinal direction compared to both ends of the side corrugated portion 11 in the longitudinal direction, and thermal deformation may be relatively large.

In addition, sloshing load due to the flow of fluid occurs in the membrane due to the nature of a ship or floating structure used in a floating state at sea, as well as thermal stress due to cryogenic LNG.

Therefore, it is necessary to continue research and development to reduce the plastic strain of the membrane so as to maintain the airtightness of the sealing wall even when various loads are applied.

On the other hand, such a membrane for a liquefied gas storage tank is formed by drawing a metal plate to form a plurality of wrinkles. The area where the wrinkles are formed has a thickness deviation according to the amount of overlapping wrinkles, that is, the thickness of the metal plate by drawing A thinned area occurs, and as a result, pressure resistance is lowered and may be vulnerable to thermal stress.

In addition, the membrane for a liquefied gas storage tank according to the prior art has a considerable area occupied by wrinkles on a metal sheet material, so it can be easily contracted and expanded due to cryogenic LNG. Since a tensile force is generated in the direction to cause deformation such as twisting, molding quality may be deteriorated and productivity may be deteriorated accordingly.

In particular, in the prior art, a thicker metal plate (eg, 1.5t, 2t, etc.) was used in order to prevent the portion from being vulnerable to thermal stress due to the thickness deviation of the wrinkle portion, resulting in an increase in the manufacturing cost of the membrane. can

The present invention is to provide a membrane for a liquefied gas storage tank capable of reducing the plastic strain due to cryogenic liquefied gas by improving the shape of the wrinkles of the membrane for a liquefied gas storage tank, thereby reducing the risk of fatigue failure. The purpose.

In addition, another object is to provide a method of manufacturing a membrane for a liquefied gas storage tank and a mold for manufacturing the membrane, which can not only reduce the manufacturing cost of the membrane, but also significantly improve the convenience of the operator to improve quality and productivity. to be

According to one aspect of the present invention, as a membrane forming a sealing wall of a liquefied gas storage tank, a membrane having a plurality of wrinkles to form a sealing wall of the liquefied gas storage tank, wherein the plurality of wrinkles are mutually connected in one direction. A pair of side pleats that are spaced apart and disposed in parallel; And a pair of center pleats disposed opposite to each other between the pair of side pleats, wherein the pair of side pleats and the pair of center pleats have different sizes applied to the membrane for a liquefied gas storage tank. this can be provided.

Based on the cross section, the height of the center pleats may be smaller than the height of the side pleats.

In addition, the height of the center pleats may be formed to be 10% to 30% smaller than the height of the side pleats.

In addition, the center wrinkle portion may be formed to have a wider width than the side wrinkle portion.

In addition, among both ends of the center pleats, an end positioned in an opposite direction facing the pair of center pleats may have a larger radius of curvature than the end of the side pleats.

In addition, among both ends of the center pleats, an end portion positioned in an opposite direction in which the pair of center pleats face each other may be formed relatively round compared to the shape of the end portion located in a direction in which the pair of center pleats face each other. .

In addition, with respect to a plane, the center pleats, doedoe having a relatively short length compared to the side pleats, may be formed to protrude more than the side pleats in an opposite direction facing the center creases.

In addition, with respect to the plane, the pair of center pleats among both ends of the pair of center pleats are located in opposite directions facing each other, and the pair of side pleats may be located on the same line as the ends of the pair. .

In addition, the pair of side wrinkles and the pair of center wrinkles may be formed by drawing a metal plate having a predetermined thickness.

According to another aspect of the present invention, as a method of manufacturing a membrane for a liquefied gas storage tank including a pair of side pleats and a pair of center pleats disposed opposite to each other between the pair of side pleats, a die mold and preparing a plurality of insert molds drawn into the die mold; and forming the plurality of wrinkles by drawing a metal plate material having a predetermined thickness using the die mold and the plurality of insert molds.

The plurality of insert molds may include side pleat inserts for forming the pair of side pleats and center pleat inserts for forming the pair of center pleats.

In addition, the die mold is provided singly to correspond to the size of the membrane, and before the step of forming the plurality of wrinkles, a step of adjusting the position of the center wrinkles by sliding the insert for center wrinkles on the die mold is further performed. can include

In addition, the die mold includes a main frame into which at least a part of the center pleat insert is inserted, and a side frame located at both ends in the longitudinal direction of the main frame and into which the remaining part of the center pleat insert is inserted,

Before the processing of the plurality of pleats, the side frame and the insert for the center pleats may be replaced according to a change in the size of the membrane.

According to another aspect of the present invention, a mold for manufacturing a membrane for a liquefied gas storage tank including a pair of side pleats and a pair of center pleats disposed opposite to each other between the pair of side pleats, die mold; and a plurality of insert molds inserted into the die mold, wherein the plurality of insert molds include side pleat inserts for forming the pair of side pleats; And a mold for manufacturing a membrane for a liquefied gas storage tank including an insert for center pleats for forming the pair of center pleats may be provided.

A pair of insert grooves may be formed in the die mold to correspond to a size of the side pleat insert so that the side pleat insert is inserted and installed.

In addition, a guide groove may be formed extending in the longitudinal direction of the die mold between the pair of insert insertion grooves to guide sliding of the center pleat insert.

In addition, the guide grooves may be formed as a pair by being disposed opposite to each other between the pair of insert insertion grooves.

In addition, the die mold may include a main frame into which at least a part of the insert for center pleats is drawn; and side frames positioned at both ends of the main frame in the longitudinal direction and into which the remaining part of the center pleat insert is retracted.

In addition, at least a portion of the center pleat insert may be inserted into the main frame, and the remaining portion of the center pleat insert may be inserted into the side frames positioned at both ends of the main frame.

In addition, a plurality of inserts for center pleats may be provided with different lengths according to the size change of the membrane.

In addition, the main frame may be provided singly, but the side frames may be provided in plural to correspond to the size of the insert for center pleats.

The present invention can greatly reduce the plastic strain by improving the shape of the wrinkles of the membrane for a liquefied gas storage tank, thereby significantly reducing the risk of fatigue failure.

In addition, in order to improve productivity and reduce manufacturing cost, the thickness of the metal plate may be reduced, but the width and height of the wrinkle portion may be changed to maintain the same stiffness as before.

In addition, since membranes of various sizes can be manufactured with a single mold, not only can the membrane manufacturing cost be reduced, but also the operator's convenience is improved and the manufacturing process is simplified, resulting in improved membrane quality and increased productivity. can have

1 is a plan view showing a part of a membrane for a liquefied gas storage tank according to the prior art.

Figure 2 is a view showing the corrugated membrane of Figure 1 separated.

3 is a plan view showing a part of a membrane for a liquefied gas storage tank according to an embodiment of the present invention.

FIG. 4 is a plan view showing a state in which different distances between the pair of center creases shown in FIG. 3 are applied.

5 is an enlarged view of a portion of a cross section of a membrane for a liquefied gas storage tank according to an embodiment of the present invention.

6 is a view schematically showing a manufacturing mold for manufacturing a membrane for a liquefied gas storage tank according to an embodiment of the present invention.

FIG. 7 is a view showing that a plurality of inserts for center pleats and side frames of different sizes are provided in the production mold shown in FIG. 6 as an example.

8 is a block diagram for explaining a method of manufacturing a membrane for a liquefied gas storage tank according to an embodiment of the present invention.

9 is a view schematically showing a modified example of a manufacturing mold for manufacturing a membrane for a liquefied gas storage tank according to an embodiment of the present invention.

FIG. 10 is a view showing that in the production mold shown in FIG. 9, an insert for center corrugation is slidably provided in a die mold.

FIG. 11 is a block diagram for explaining a method of manufacturing a membrane using the manufacturing mold shown in FIG. 10 .

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

First, in adding reference numerals to components of each drawing, it should be noted that the same components have the same numerals as much as possible even if they are displayed on different drawings.

In addition, in describing the present invention, if it is determined that a detailed description of a related known configuration or function may obscure the gist of the present invention, the detailed description will be omitted.

Preferred embodiments of the present invention will be described below, but the technical spirit of the present invention is not limited or limited thereto and can be modified and implemented in various ways by those skilled in the art, of course.

The liquefied gas storage tank can be used to store liquid cargo containing hydrocarbon components that are liquefied at cryogenic temperatures, such as LNG and LPG, in particular, and has a membrane-type storage having a heat insulation layer and a sealing wall to store cryogenic liquid cargo such as LNG. It could be a tank.

In the description of the present invention, liquefied gas is generally liquefied, such as cryogenic (approximately -163 ° C) LNG (Liquified Natural Gas), LPG (Liquefied Petroleum Gas) or liquefied ethylene gas (Liquefied Ethylene Gas). It may include all gaseous fuels stored as , and liquefied gas may mean liquefied gas as well as liquefied gas in a liquid state.

In the case of a KC-1 type tank, the insulation layer and the sealing wall of the liquefied gas storage tank are formed by combining a plurality of insulation panels on the inner wall of the hull to form one insulation layer, and the sealing wall having one or more layers on the plurality of insulation panels created through the installation process.

The present invention relates to a membrane for a liquefied gas storage tank for forming a sealing wall of the liquefied gas storage tank. By bonding, it is possible to form a sealing wall of the liquefied gas storage tank.

FIG. 3 is a plan view of a part of a membrane for a liquefied gas storage tank according to an embodiment of the present invention, and FIG. 4 is a plan view showing a state in which different distances between a pair of center corrugated parts shown in FIG. 3 are applied. FIG. 5 is an enlarged view of a portion of a cross section of a membrane for a liquefied gas storage tank according to an embodiment of the present invention.

Referring to FIG. 3 , the membrane 100 for a liquefied gas storage tank according to an embodiment of the present invention includes a plurality of wrinkles 110 for absorbing thermal stress that may occur during contraction and expansion due to cryogenic liquefied gas. , 130).

The

pleats

110 and 130 are spaced apart from each other and disposed in parallel with the pair of side pleats 110 and the pair of side pleats 110 between the pair of side pleats 110 in the longitudinal direction. It may include a pair of center wrinkles 130 disposed opposite to each other.

In the membrane 100 of this embodiment, a pair of side wrinkles 110 and a pair of center wrinkles 130 may be formed by drawing a metal plate having a predetermined thickness, and the width is short and It may have a long rectangular shape.

The pair of side corrugations 110 may be formed long along the longitudinal direction of the membrane 100 and may be spaced apart from each other and disposed in parallel in the width direction of the membrane 100 .

Here, the pair of side pleats 110 may be formed symmetrically with respect to the central portion of the membrane 100 .

In other words, based on the plane shown in FIG. 3, the pair of side pleats 110 may be spaced apart from the center or edge of the membrane 100 by the same distance, respectively, and the pair of side pleats 110 (110) It may be preferable that each longitudinal center be located on an imaginary straight line (not shown) perpendicular to the longitudinal direction of the membrane 100 and passing through the center of the membrane 100.

The pair of center pleats 130, similar to the pair of side pleats 110, are formed long along the longitudinal direction of the membrane 100, but relatively short compared to the pair of side pleats 110. can have any length.

In addition, the pair of center pleats 130 are disposed opposite to each other in the longitudinal direction of the membrane 100 between the pair of side pleats 110, so that they are symmetrical to each other with respect to the center of the membrane 100. can

In the membrane 100 for a liquefied gas storage tank according to an embodiment of the present invention, a plurality of

wrinkles

110 and 130 are formed on a metal plate to reduce thermal stress generated during contraction and expansion due to cryogenic liquefied gas. may have the effect of absorbing

In this embodiment, the distance (d1) between the pair of side pleats 110 may be fixed, but the distance (d2) between the pair of center pleats 130 is the size (or , length), the size of the membrane 100 (or metal plate), or the position of the membrane 100 on the inner wall of the hull.

For example, the pair of center pleats 130 have a relatively short length compared to the pair of side pleats 110, based on the plane shown in FIG. 3, the pair of center pleats 130 ) May be formed to protrude more than the pair of side wrinkles 110 in the opposite direction facing each other.

Here, the distance d2 between the pair of center wrinkles 130 may be formed to be relatively larger than the distance d1 between the pair of side wrinkles 110 .

In this embodiment, when the pair of center wrinkles 130 are formed to protrude more than the pair of side wrinkles 110, the area of the central flat surface of the membrane 100 is increased compared to the prior art, so that the cryogenic It may have an effect of reducing distortion of the membrane 100 due to liquefied gas.

In addition, as shown in FIG. 4, the pair of center pleats 130 have a relatively short length compared to the pair of side pleats 110, and the pair of center pleats 130 face each other. The ends in the opposite direction to see and both ends of the pair of side corrugations 110 may be spaced apart from both ends in the longitudinal direction of the membrane 100 by the same distance, and may be arranged in a virtual plane parallel to the width direction of the membrane 100. It may be located on a straight line (unsigned).

In this embodiment, the distance d2 between the pair of center pleats 130 is the opposite end of the pair of center pleats 130 facing each other at both ends of the pair of side pleats 110. It may have a minimum value when located on the same line as , and a maximum value may be applied differently depending on the arrangement method of the membrane 100 or the result of stress analysis.

Hereinafter, for convenience of explanation, reference numerals are given to both ends 111 in the longitudinal direction of the side pleats 110, and a pair of center pleats 130 among both ends of the center pleats 130 in the longitudinal direction. To divide the end located in the direction facing each other into the inner end 131 and the outer end 133, the end located in the opposite direction where the pair of center pleats 130 face each other.

That is, the inner end 131 of the center pleat 130 is located between the pair of side pleats 110, and the outer end 133 of the center pleat 130 is of the side pleat 110. It may be disposed more adjacent to both ends in the longitudinal direction of the membrane 100 compared to both ends 111, and the outer end 133 of the center pleat 130 and both ends 111 of the side pleat 110 are It may be arranged spaced apart by the same distance from both ends in the longitudinal direction of (100).

A method of making the distance d2 between the pair of center pleated parts 130 different from each other will be described later.

Meanwhile, in the membrane 100 of the present embodiment, a pair of side wrinkles 110 and a pair of center wrinkles 130 may be formed by drawing a metal plate. As described above, in the prior art, wrinkles A thick metal plate (eg, 1.5t, 2t, etc.) was used to compensate for the thickness deviation of the portion, which may result in a decrease in productivity and an increase in cost.

The membrane 100 for a liquefied gas storage tank according to an embodiment of the present invention reduces the thickness of the metal plate in order to improve productivity and reduce the manufacturing cost of the membrane 100 in the manufacturing process, but the size of the wrinkles (height and / or width) to maintain the same or similar stiffness to the existing one.

In this embodiment, the metal sheet may have a thickness relatively smaller than the thickness of a metal sheet used in manufacturing a conventional membrane having a plurality of wrinkles having the same size and shape, may have a thickness of 1.2t, or may have a thickness of 1.0t. may have a thickness of

Here, the pair of side pleats 110 and the pair of center pleats 130 may have different sizes.

5 is an enlarged view of a portion of the cross section of a membrane for a liquefied gas storage tank according to an embodiment of the present invention, and the height h1 and width w1 of the side pleats 110 and the center pleats 130 ) is a diagram showing the comparison of the height (h2) and the width (w2).

Specifically, as shown in FIG. 5 , the height h2 of the center corrugated portion 130 may be smaller than the height h1 of the side corrugated portion 110 .

In this embodiment, it may be preferable that the height h2 of the center pleat 130 is smaller than the height h1 of the side pleat 110 by 10% to 30%, more preferably , It may be formed 20% smaller than the height h1 of the side wrinkle portion 110.

In addition, the pair of side pleats 110 and the pair of center pleats 130 of this embodiment may have different widths as well as heights.

Specifically, as shown in FIG. 5 , the width w2 of the center wrinkle part 130 may be greater than the width w1 of the side wrinkle part 110 .

That is, the height (h2) of the center crease 130 is formed relatively small compared to the height (h1) of the side crease 110, and the width (w2) of the center crease 130 is the side crease 110 It may be formed larger than the width (w2) of.

In this embodiment, the width (w2) of the center wrinkle portion 130 may be preferably formed to be 10% to 30% larger than the width (w1) of the side wrinkle portion 110, more preferably, It may be formed to be 20% larger than the width w1 of the side wrinkle portion 110 .

To elaborate, the membrane 100 of this embodiment is prepared by processing a metal material thinner than the membrane 10 described in the prior art, and the height h1 and width w of the side corrugated portion 110 are conventional. In technology, it may be formed smaller than the height and width of the

pleats

11 and 13 by 70% to 90% (more preferably, 80%).

In addition, the center pleats 130 of this embodiment are formed to have a height h2 that is 10% to 30% (more preferably 20%) smaller than the height h1 of the side pleats 110. It is formed to have a width w2 that is 10% to 30% (more preferably, 20%) larger than the width w2 of the wrinkles 110, and is the same as or similar to the widths of the

wrinkles

11 and 13 in the prior art. can have

Conventionally, a thick metal plate was used to compensate for the thickness variation of the wrinkles, but in the membrane 100 of this embodiment, the height h2 of the center wrinkles 130 is greater than the height h1 of the side wrinkles 110. In addition to being small, the width w2 of the center corrugation part 130 is large compared to the width w1 of the side corrugation part 110, so that the pressure resistance performance of the membrane 100 can be improved without increasing the thickness of the metal plate. can have an effect.

In addition, by reducing the thickness of the metal sheet compared to the prior art and improving the shape of the wrinkles, the amount of plastic deformation such as distortion due to drawing of the metal sheet or thermal deformation due to cryogenic liquefied gas can be reduced, resulting in quality improvement and increase in productivity can be expected.

On the other hand, in the membrane for a liquefied gas storage tank according to the prior art, the side pleats 11 and the central wrinkles 13 are formed to have the same size and shape, and the membrane ( Stress is concentrated at the end of the central wrinkled portion 13 formed to protrude in the longitudinal direction of 10), and thus thermal deformation may be relatively large.

In other words, the maximum strain is at the end of both ends of the central wrinkled part 13 located in the opposite direction where the pair of central wrinkled parts 13 face each other and relatively adjacent to both ends in the longitudinal direction of the membrane 10. may occur.

The present invention improves not only the size of the plurality of

wrinkles

110 and 130 formed on the membrane 100 but also the shape of the ends of at least some of the plurality of

wrinkles

110 and 130, thereby reducing stress concentrated in a specific region and membrane ( 100) to reduce the plastic strain.

In this embodiment, one end protruding outward from both ends 111 of the pair of side pleats 110 among both ends of the center pleats 130, that is, the pair of center pleats 130 ) The outer end portion 133 located in the opposite direction facing each other may be formed to be relatively round compared to the shape of both ends 111 of the side wrinkle portion 110 relative to the plane.

In addition, the outer end portion 133 of the present embodiment may have a larger radius of curvature than both ends 111 of the side pleat portion 110 as the width w2 of the center pleat portion 130 increases.

Here, the inner end portion 131 of the center pleat portion 130 may have the same shape as the outer end portion 133, and similarly to both end portions 111 of the pair of side pleat portions 110, it is pointed. may have a shape.

Unlike the prior art in which the plurality of

wrinkles

11 and 13 have the same size and shape, the membrane 100 for a liquefied gas storage tank according to an embodiment of the present invention has a width (w2) of the center wrinkles 130 ) In addition to increasing, by forming a round shape of the outer end portion 133 located in the opposite direction where the pair of center wrinkles 130 face each other, it is possible to reduce the stress concentrated on the corresponding portion as well as , the plastic strain of the membrane 100 is greatly reduced, which can have an effect of reducing the risk of fatigue failure.

On the other hand, when manufacturing a membrane for a liquefied gas storage tank, it is common to replace a mold according to the size of the membrane to be manufactured. Worker's convenience may be reduced due to heavy mold replacement work.

6 is a schematic plan view of a manufacturing mold for manufacturing a membrane for a liquefied gas storage tank according to an embodiment of the present invention, and FIG. 7 is a center pleat insert and side in the manufacturing mold shown in FIG. 6 It is a view showing that a plurality of frames are provided with different sizes as an example, and FIG. 8 is a block diagram for explaining a method of manufacturing a membrane for a liquefied gas storage tank according to an embodiment of the present invention.

Referring to FIG. 6 , a mold for manufacturing a membrane for a liquefied gas storage tank according to an embodiment of the present invention is inserted into a die mold 210 and the die mold 210 to form a plurality of

wrinkles

110 and 130 . It may include a plurality of insert molds 230 for doing.

In this embodiment, the die mold 210 may be composed of a main frame 211 and side frames 213 located at both ends of the main frame 211 in the longitudinal direction, and a plurality of insert molds 230, a pair It may include a side pleat insert 231 for forming the side pleats 110 and a center pleat insert 233 for forming a pair of center pleats 130 .

A pair of insert insertion grooves 211a into which inserts 231 for side pleats are inserted may be formed in the main frame 211 .

In this embodiment, at least a part of the center pleat insert 233 may be inserted at both ends of the main frame 211 in the longitudinal direction, and the remaining part of the center pleat insert 233 is in the longitudinal direction of the main frame 211. It can be introduced into the side frame 213 located at both ends.

On the other hand, in the membrane 10 for a liquefied gas storage tank according to the prior art, even if the size is changed according to the installation position of the membrane 10, the length of the side pleats 11 may not change, but the pair of side surfaces The length of the central pleats 13 located between the pleats 11 must be varied.

In order to manufacture such a membrane, in the prior art, a plurality of molds corresponding to the sizes of various membranes 10 were required, and in particular, a pair of inserts having a fixed size was provided to form the side wrinkles 11 , As a plurality of inserts for forming the central wrinkle portion 13 are provided with different lengths, not only the number of molds and inserts increases excessively, but also the manufacturing process of the membrane may become complicated.

Similar to the prior art, in the mold for manufacturing a membrane for a liquefied gas storage tank according to an embodiment of the present invention, a pair of inserts 231 for side pleats are fixed in size, and a pair of inserts for side pleats The main frame 211 into which the 231 is drawn may be provided as a single unit having a fixed size.

On the other hand, a plurality of inserts 233 for center pleats may be provided with different lengths to correspond to the change in size of the membrane (see (a) in FIG. 7), and side frames located at both ends of the main frame 211. 213 may also be provided in plurality to correspond to the size of the center pleat insert 233 (see (b) in FIG. 7).

The production mold of this embodiment may be used to manufacture the membrane 100 shown in FIG. 3 or 4, but the present invention is not limited thereto, and the membrane 10 according to the prior art shown in FIGS. 1 to 2 ) can also be used to make

Conventionally, the entire mold and insert had to be replaced according to the change in the size of the membrane. Since the frame 211 can be used in the same way, it can have the effect of reducing the manufacturing cost of the membrane and simplifying the manufacturing process.

Hereinafter, a method for manufacturing a membrane for a liquefied gas storage tank using a manufacturing mold according to an embodiment of the present invention will be briefly described.

In the manufacturing method of a membrane for a liquefied gas storage tank according to an embodiment of the present invention, a pair of side pleats 110 and a pair of center pleats disposed opposite to each other between the pair of side pleats 110 As a method for manufacturing the membrane 100 including the portion 130, as shown in FIG. 8, preparing a die mold 210 and a plurality of insert molds 230 drawn into the die mold 210 It may include a step (S110) and a step (S150) of drawing a metal sheet having a predetermined thickness using the die mold 210 and the plurality of insert molds 230.

The die mold 210 may be composed of a main frame 211 and side frames 213 located at both ends in the longitudinal direction of the main frame 211, and the plurality of insert molds 230 include a pair of side corrugations ( 110) and a center pleat insert 233 for forming a pair of center pleats 130.

In the present embodiment, before the step of processing the metal plate (S150), a step of replacing the side frame 213 and the center corrugation insert 233 according to the size change of the membrane (S130) may be further included.

On the other hand, in the manufacturing mold of this embodiment, cost reduction and convenience are improved by reducing the number and size of the molds to be replaced, but the position adjustment of the center wrinkle part 130, that is, between the pair of center wrinkle parts 130 The distance d2 (see FIGS. 3 and 4 ) cannot be changed, and the main frame 211 must be replaced in order to adjust the position of the center corrugated part 130 .

FIG. 9 is a view showing a modified example of a mold for manufacturing a membrane for a liquefied gas storage tank according to an embodiment of the present invention, and FIG. 10 is a view showing an insert for center pleats sliding into a die mold in the manufacturing mold shown in FIG. 9 . FIG. 11 is a block diagram for explaining a method of manufacturing a membrane using the manufacturing mold shown in FIG. 9 .

Referring to FIG. 9 , the manufacturing mold of this modified example may include a die mold 250 and a plurality of insert molds 270 drawn into the die mold 250, similarly to the above-described embodiment.

The die mold 250 and the plurality of insert molds 270 of this modified example are distinguished by applying different reference numerals from those of the above-described embodiment.

In this modified example, the plurality of insert molds 270, similar to the above-described embodiment, inserts for side pleats 271 for forming a pair of side pleats 110, and a pair of center pleats An insert 273 for center pleats to form 130 may be included.

The die mold 250 of this modified example may be provided singly to correspond to the size of the membrane, and a pair of inserts corresponding to the size of the side pleat inserts 271 so that the inserts 271 for side pleats are retracted and installed. An insertion groove 251 may be formed.

In this modified example, a guide groove 253 may be formed extending in the longitudinal direction of the die mold 250 between the pair of insert insertion grooves 251 .

The guide groove 253 may serve to guide the sliding of the center pleat insert 271 .

In this modified example, it may be preferable that the guide grooves 253 are arranged to face each other between the pair of insert insertion grooves 251 and form a pair.

In the manufacturing mold of this modified example, the die mold 250 is provided as a single unit to correspond to the size of the membrane 100, and the center pleat insert 273 is slid into the guide groove 253 to form the center wrinkle portion 130. The position can be easily adjusted.

The center pleat insert 273 of this modified example may be slidably movable in a direction in which the pair of center pleat inserts 273 face each other within the guide groove 253, that is, toward the center of the die mold 250. On the contrary, it can be natural that the sliding movement may be possible in a direction away from the center of the die mold 250.

That is, even if the size of the membrane 100 is changed, only the position of the center pleat 130 is adjusted, that is, the insert 273 for the center pleat is slid in the longitudinal direction within the guide groove 253 to provide various sizes. Since the membrane 100 can be manufactured, it is possible to have an effect of reducing the manufacturing cost of the membrane and simplifying the manufacturing process due to a single mold.

To briefly describe the method of manufacturing a membrane for a liquefied gas storage tank using the manufacturing mold of this modified example, as shown in FIG. 11, a die mold 250 and a plurality of insert molds 270 drawn into the die mold 250 ) and drawing a metal sheet having a predetermined thickness using the die mold 250 and the plurality of insert molds 270 (S250). Prior to the step of adjusting the position of the center pleat part 130 by sliding the center wrinkle insert 273 on the die mold 250 (S230) may be further included.

The production mold shown in FIGS. 6 and 9 is a lower template on which a metal plate is placed, and the present invention may further include an upper template (not shown) that is positioned opposite to the metal plate and presses the metal plate. And, the upper template may have a groove corresponding to the insert mold of this embodiment.

In the method of manufacturing a membrane for a liquefied gas storage tank according to an embodiment of the present invention, since membranes of various sizes can be manufactured with a single mold, not only can the manufacturing cost of the membrane be reduced, but also the operator's convenience is greatly improved. It can have the effect of improving quality and productivity.

The membrane for a liquefied gas storage tank according to an embodiment of the present invention can be applied to any ship or offshore structure used while floating in the sea where flow occurs, and can be applied to a liquefied gas carrier or LNG RV that transports LNG or LPG. It can be applied to ships such as (LNG Regasification Vessel) as well as offshore plants such as LNG Floating, Production, Storage and Offloading (FPSO) or LNG Floating Storage and Regasification Unit (FSRU).

It can be taken for granted that the present invention can be equally applied to a liquefied gas storage tank installed on land as well as a liquefied gas storage tank installed inside the hull of a ship or marine structure.

The above description is merely an example of the technical idea of the present invention, and those skilled in the art can make various modifications, changes, and substitutions without departing from the essential characteristics of the present invention. will be.

The embodiments disclosed in the present invention and the accompanying drawings are not intended to limit the technical idea of the present invention, but to explain, and the scope of the technical idea of the present invention is not limited by these embodiments and the accompanying drawings.

In addition, the protection scope of the present invention should be construed according to the claims below, and all technical ideas within the equivalent range should be construed as being included in the scope of the present invention.

Claims

A membrane having a plurality of wrinkles to form a sealing wall of a liquefied gas storage tank,

The plurality of wrinkles,

A pair of side pleats spaced apart from each other in one direction and disposed in parallel; and

Including a pair of center pleats disposed opposite to each other between the pair of side pleats,

A membrane for a liquefied gas storage tank in which the pair of side pleats and the pair of center pleats have different sizes.
According to claim 1,

Membrane for a liquefied gas storage tank, based on the cross section, the height of the center pleats is smaller than the height of the side pleats.
According to claim 1,

A membrane for a liquefied gas storage tank in which the height of the center pleats is 10% to 30% smaller than the height of the side pleats.
According to claim 1 or 2,

The center pleat portion is a membrane for a liquefied gas storage tank in which a width is formed wider than the side pleat portions.
According to claim 4,

Membrane for a liquefied gas storage tank, wherein an end portion of both ends of the center pleat portion located in an opposite direction facing the pair of center pleat portions has a larger radius of curvature than the end portion of the side pleat portion.
According to claim 5,

Of the both ends of the center pleats, the end portion located in the opposite direction facing the pair of center pleats is a liquefied gas storage tank formed relatively round compared to the shape of the end portion located in the direction in which the pair of center pleats face each other. membrane for.
According to claim 1,

Based on the plane, the center pleats have a relatively short length compared to the side pleats, and the center pleats are formed to protrude from the side pleats in the opposite direction facing each other.
According to claim 1,

On the basis of a plane, the liquefied gas storage tank where the end of the pair of center pleats located in the opposite direction of the pair of center pleats is located on the same line as the end of the pair of side pleats among both ends of the pair of center pleats membrane for.
According to claim 1,

The pair of side pleats and the pair of center pleats are formed by drawing a metal plate having a predetermined thickness.
As a liquefied gas storage tank for storing liquefied gas,

A heat insulating layer formed by combining a plurality of heat insulating panels on the inner wall of the hull;

And a sealing wall forming one or more layers on the plurality of insulation panels,

The membrane for forming the sealing wall,

A pair of side pleats spaced apart from each other in one direction and disposed in parallel; and

Including a pair of center pleats disposed opposite to each other between the pair of side pleats,

The liquefied gas storage tank in which the pair of side pleats and the pair of center pleats have different sizes.