KR102537531B1 - Secondary barrier for liquefied gas storage tank - Google Patents

Abstract

The present invention is a secondary barrier for a liquefied gas storage tank, comprising at least one polymer selected from the group consisting of polyethylene, polyethylene terephthalate, polyvinyl alcohol, ethylene vinyl alcohol and nylon. blocking layer; and a fiber layer laminated on both sides of the blocking layer, wherein the fiber layer is fixed by an adhesive layer.

Description

Secondary barrier for liquefied gas storage tank}

The present invention relates to a secondary barrier for a liquefied gas storage tank.

In general, hydrocarbons such as natural gas and ethylene are liquefied at a low temperature after production and stored and transported in the form of liquefied gas. For example, natural gas can be cooled to -163 °C and treated in the form of liquefied gas. Accordingly, in a floating offshore structure or ship that produces or transports liquefied gas, a storage tank structure for stably storing liquefied gas in a low temperature state is required.

An insulating wall for insulation and a barrier structure for liquid-tightness of stored liquefied gas are provided on the inner wall of the liquefied gas storage tank, and a secondary barrier structure has been utilized. A secondary insulation wall and a secondary barrier may be laminated on the inner wall of the liquefied gas storage tank, a primary insulation wall and a primary barrier may be laminated on the secondary barrier, and the primary barrier may be in contact with the liquefied gas. there is. The secondary barrier may provide an airtight structure that prevents leakage of liquefied gas, and even if the primary barrier is damaged, it may be provided to withstand approximately two weeks until the ship moves to the port and unloads the liquefied gas.

Referring to FIG. 1, as a conventional secondary barrier, an adhesive layer 11 is formed on both sides of a metal blocking layer 10 such as aluminum foil or a stainless sheet, and a fiber layer including glass fibers is formed on the adhesive layer 11 ( A structure in which glass cloth, 12) was laminated was adopted. As the adhesive layer 11 used to laminate the metal blocking layer 10 and the fiber layer 12, a polyurethane-based adhesive was used. The adhesive layer 11 receives cold heat directly or indirectly from cryogenic liquefied gas and repeats contraction and expansion. The barrier layer 10 is a thin metal layer of tens to hundreds of micrometers and has a low tear strength, which causes tearing. there was. In addition, the barrier layer 10 made of metal is easily corroded by moisture, so damage caused by moisture in the surrounding air condensed by handling cryogenic liquefied gas or secondary damage caused by exposure to seawater when damage to the outer wall of the hull occurs. There was a disadvantage that the strength of the entire barrier was lowered.

The present invention was created to solve the problems of the prior art as described above, and an object of the present invention is a secondary barrier that exhibits excellent tensile strength and shear strength even in a cryogenic environment by using a barrier layer containing a polymer that does not cause corrosion. and a manufacturing method thereof.

The secondary barrier according to one aspect of the present invention is for a liquefied gas storage tank of a liquefied gas carrier, and includes one or more polymers selected from the group consisting of polyethylene, polyethylene terephthalate, polyvinyl alcohol, ethylene vinyl alcohol and nylon. layer, and a fiber layer laminated on both sides of the blocking layer, and the fiber layer may be fixed by an adhesive layer.

Specifically, the polymer may have a density of 0.9 to 1.7 g/cm ³ .

Specifically, the blocking layer may be formed by depositing one or more metals or metal oxides selected from aluminum, copper, and oxides thereof on at least a portion thereof.

Specifically, the fiber layer may include one or more fibers selected from the group consisting of glass fibers, polyethylene fibers, polyparaphenylene benzobisoxazole fibers, aramid fibers, and carbon fibers.

Specifically, the fiber layer may include polyethylene fibers, and the adhesive layer may include a thermoplastic polyethylene-based compound.

Specifically, the adhesive layer may include at least one of linear low density polyethylene and ethylene vinyl acetate.

Specifically, the adhesive layer, has a melting point lower than the melting point of the fiber layer, the melting point of the adhesive layer may be 90 to 120 ℃.

Another aspect of the present invention is a liquefied gas storage tank including a secondary barrier according to one aspect of the present invention, the secondary insulation wall fixed to the hull, the secondary barrier, the primary insulation wall and the primary barrier It is characterized by being arranged in order.

Specifically, the secondary barrier may be bonded and disposed on the secondary thermal insulation wall, and the primary barrier may be welded and disposed on the primary thermal insulation wall.

The present invention provides a secondary barrier with improved durability based on excellent tear strength even in a cryogenic environment by using a polymer barrier layer having excellent corrosion resistance and tear strength compared to conventional metal or alloy materials, and at the same time, at a low specific gravity It is possible to achieve weight reduction by improving workability and driving fuel efficiency.

1 is a cross-sectional view of a secondary barrier including a conventional fibrous layer.
2 is a cross-sectional view of a secondary barrier according to an embodiment of the present invention.
3 is a conceptual diagram illustrating a method for manufacturing a secondary barrier according to an embodiment of the present invention.
4 is a conceptual diagram showing a method for manufacturing a secondary barrier according to another embodiment of the present invention.

Objects, specific advantages and novel features of the present invention will become more apparent from the following detailed description and preferred embodiments taken in conjunction with the accompanying drawings. In adding reference numerals to components of each drawing in this specification, it should be noted that the same components have the same numbers 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 related known technologies may unnecessarily obscure the subject matter of the present invention, the detailed description will be omitted.

Hereinafter, the liquefied gas may be LNG or ethane having a low boiling point.

In the following, it should be noted that high pressure, low pressure, high temperature, low temperature, high strength and low strength are relative and do not represent absolute values.

Hereinafter, it should be noted that a liquefied gas carrier is an expression encompassing all cargo-carrying ships, merchant ships, and ships capable of producing natural gas in the sea.

Hereinafter, the secondary barrier is disposed on the secondary insulation wall fixed to the hull, RSB (Rigid Secondary Barrier) provided to cover the secondary insulation wall and FSB (Flexible Secondary Barrier) provided to cover two or more RSBs ) can mean encompassing.

Hereinafter, a metal material may include a single metal or an alloy including two or more metals.

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

1 is a cross-sectional view of a conventional secondary barrier.

Referring to FIG. 1, the secondary barrier has a structure in which an adhesive layer 11 and a fiber layer 12 are sequentially laminated on both sides of the blocking layer 10 with the blocking layer 10 made of a metal as the center.

The blocking layer 10 may be an aluminum foil or a stainless sheet, but is not limited thereto, and a material having a face-centered cubic structure, such as an austenitic stainless steel or a copper alloy, suitable for a cryogenic environment may be used. However, the barrier layer 10 made of such a metal has a limitation in that it has low tear strength and is vulnerable to corrosion.

The adhesive layer 11 is a polyurethane-based adhesive, and may be a thermoplastic polyurethane adhesive (TPU) that is melted by heat to bond the barrier layer 10 and the fiber layer 12 and then cured.

The fiber layer 12 may be a fabric layer having improved strength by impregnating glass fibers into a resin and hardening them. Polyurethane-based or epoxy-based adhesives used in the construction process of the secondary barrier have a limitation in that the secondary barrier exhibits a low durability life as it causes tear damage to the secondary barrier by hard and sharp edges after adhesive curing.

2 is a cross-sectional view of a secondary barrier 1 according to an embodiment of the present invention.

The secondary barrier 1 according to an embodiment of the present invention may include a blocking layer 10, and may be formed by stacking an adhesive layer 20 and a fiber layer 30 on both sides of the blocking layer 10.

The blocking layer 10 may be a polymer blocking layer 10 containing a polymer, and may serve to prevent leakage of liquefied gas through the liquid-tightness and airtightness of the secondary barrier 1. For example, the blocking layer 10 may include one or more polymers having a density of 0.9 to 1.7 g/cm ³ . The conventional metal blocking layer is made of metal such as aluminum and has a density of about 2.7 g/cm ³ or more, and accordingly, when applied to a liquefied gas storage tank, its weight reaches several tons. In this embodiment, a polymer having excellent corrosion resistance is used as the barrier layer 10, and it is possible to improve workability due to light weight while securing excellent tear strength compared to metal.

Specifically, the blocking layer 10 according to this embodiment is selected from the group consisting of polyethylene (PE), polyethylene terephthalate (PET), polyvinyl alcohol (PVA), ethylene vinyl alcohol (EVOH) and nylon (Nylon) Including one or more polymers that are, it can improve the tear strength compared to conventional metal materials such as aluminum and exhibit excellent resistance to corrosion at the same time. The main characteristics of the conventional metal material and the polymer material for use in the blocking layer 10 according to the present embodiment are shown in Table 1 below. Gas barrier properties and corrosion resistance were indicated as excellent: 5, good: 4, average: 3, weak: 2, and corrosion or weak: 1.

division type density
(g/cm ³ ) gas
barrier corrosion resistance thermal expansion
Coefficient
(×10 ^-6 /K) Elastic modulus (GPa) tensile strength
(MPa) metal
Material aluminum 2.7 5 One 23.1 69 700 beryllium copper 8.25 5 One 17 125 to 130 965 to 1205 copper 8.94 5 One 17 to 18 121 to 133 210 SUS304 8 5 One 17.3 193 to 200 215 to 505 polymer
Material ultra high molecular weight
polyethylene 0.93 2 5 150 0.83 40 polyethylene
terephthalate 1.35 3 5 60 2 to 2.7 54.5 polyvinyl alcohol 1.2 4 3 275 4.74 480 Ethylene Vinyl Alcohol 1.2 4 3 40 to 150 1.1 to 3.1 75 nylon 1.65 5 5 17 18.5 300

The polyethylene may be high molecular weight polyethylene having a molecular weight of 1 million to 7 million, and may be ultra high molecular weight polyethylene (UHMWPE) having a molecular weight of 3.5 million to 7.5 million. Ultrahigh molecular weight polyethylene has a density of approximately 0.9 to 1.0 g/cm ³ , is suitable for use at cryogenic temperatures, and has excellent corrosion resistance including water resistance, chemical resistance and abrasion resistance. Polyethylene terephthalate has a density of approximately 1.1 to 1.5 g/cm ³ , is suitable for use at cryogenic temperatures, and has excellent water resistance. Polyvinyl alcohol has a density of approximately 1.0 to 1.3 g/cm ³ , is suitable for use at cryogenic temperatures, and has excellent gas barrier properties. Ethylene vinyl alcohol has a density of approximately 1.0 to 1.3 g/cm ³ , is suitable for use at extremely low temperatures, and has excellent gas barrier properties. Nylon has a density of approximately 1.1 to 1.7 g/cm ³ , is suitable for use at cryogenic temperatures, and has excellent gas barrier properties and water resistance. Nylon can be, for example, nylon-6, nylon-66, nylon-MXD6, and the like.

Additionally, the blocking layer 10 according to the present embodiment may be formed by depositing one or more metals selected from aluminum and copper or oxides thereof on at least a portion of the blocking layer 10 . Ceramics containing aluminum oxide may be used as the metal oxide. Accordingly, the blocking layer 10 may be a polymer layer including the aforementioned polymer, and a metal deposited on at least a portion of the surface of the blocking layer 10 may be used. Metal deposition may be either chemical vapor deposition or physical vapor deposition. It may be desirable to deposit metal on both sides of the blocking layer 10 .

Polyethylene and polyethylene terephthalate among polymers that can be used as the barrier layer 10 may have relatively low gas barrier properties compared to polyvinyl alcohol, ethylene vinyl alcohol, and nylon. By depositing a metal or an oxide thereof on the surface of such polyethylene or polyethylene terephthalate, the gas barrier property of the barrier layer 10 can be increased to improve the liquid-tightness and airtight performance of the secondary barrier 1. However, the present embodiment is not limited thereto, and gas barrier properties can be further increased by depositing a metal or its oxide on the surfaces of polyvinyl alcohol, ethylene vinyl alcohol, and nylon, which have relatively excellent gas barrier properties. In addition, deposition of a metal or an oxide thereof on the barrier layer 10 not only improves the gas barrier properties of the barrier layer 10, but also increases the surface energy of the barrier layer 10 relatively, thereby increasing the adhesive layer 20 described later. It is possible to provide an effect of improving adhesion to.

The adhesive layer 20 is formed on both sides of the blocking layer 10 so that the fiber layer 30 to be described later can be bonded to the blocking layer 10 by bonding. The adhesive layer 20 may be disposed by applying an adhesive composition on both sides of the barrier layer 10 or by laminating a separate layer such as an adhesive film or sheet.

When the blocking layer 10 includes a polyethylene-based polymer such as polyethylene or polyethylene terephthalate, adhesion to the fiber layer 30 through the adhesive layer 20 is improved because it has a relatively low surface energy compared to conventional metal blocking layers. difficult. Therefore, in the present embodiment, when the barrier layer 10 includes at least one of polyethylene and polyethylene terephthalate, a polyethylene-based compound, which is a polymer of the same type, is used as the adhesive layer 20 to prevent adhesion problems of the barrier layer 10. will be able to solve

Specifically, the adhesive layer 20 may be formed by an adhesive composition containing a polyurethane-based or polyethylene-based compound, an adhesive film, or an adhesive sheet. A thermoplastic adhesive layer may be used.

Preferably, the polyethylene-based compound is one in which one or more functional groups are bonded to a polyethylene main chain as a side chain, and at least a portion of the compound may be modified by bonding with a polar functional group. Modification of at least a portion of a compound may mean that functional groups are crosslinked with respect to the compound in a manner such as graft polymerization to form branches.

For example, the adhesive layer 20 may be formed by polymerization of one or more functional groups having polarity in polyolefin, or polymerization of one or more functional groups so that the entire polyolefin has polarity.

For example, the adhesive layer 20 may be formed using an adhesive film containing at least one of linear low density polyethylene (LLDPE) and ethylene vinyl acetate (EVA).

Additionally, the adhesive layer 20 may include a polymer having a melting point of 90 to 120°C. The fiber layer 30 including polyethylene fibers has a melting point of about 140 ° C., and the adhesive strength to the fiber layer 30 is improved by using a polymer of the same type as the fiber layer 30 as a backbone, but the melting point is lower than that of the fiber layer 30. By forming the adhesive layer 20 as a furnace, it is possible to manufacture the secondary barrier 1 even under relatively low temperature conditions. Accordingly, the adhesive layer 20 of the present embodiment is placed between the fiber layer 30 and the barrier layer 10 and heat is applied to melt only the adhesive layer 20, and the polyethylene fibers and the fiber layer 30 including the same It is possible to bond the fiber layer 30 and the blocking layer 10 without damage to them.

According to this embodiment, an aluminum foil having a thickness of 70 μm is used as the metal layer 10, and an adhesive film containing LLDPE having a melting point of about 113 ° C. and a fibrous layer 30 containing polyethylene fibers are sequentially pressed and laminated on both sides, , The formation of the adhesive layer 20 according to various temperatures and the adhesive strength to the adjacent layer were confirmed through a heating furnace, and are shown in Table 2 below.

Heating temperature (℃) Adhesion strength (MPa) 110 No adhesive layer formed 115 7.2 120 8.9 130 13.3 140 12.1 150 fiber layer damage

As shown in Table 2, the adhesive layer 20 itself is not formed at a temperature lower than the melting point (115° C.) of the adhesive film, and the adhesive film melts and hardens from the temperature corresponding to the melting point, thereby forming the adhesive layer 20. formed, but showed the greatest adhesive strength at 130° C. and then decreased. It can be seen that the adhesive strength of the formed adhesive layer 20 is not necessarily proportional to the heating temperature. In the case of forming the adhesive layer 20 according to this embodiment, it was confirmed that the adhesive layer 20 exhibits an adhesive strength of up to 5 MPa at room temperature and up to 12 MPa at a cryogenic temperature (-170 ° C).

The adhesive layer 20 may have a thickness of 0.05 to 0.3 mm. If the thickness of the adhesive layer 20 is less than 0.05 mm, the bonding strength between the barrier layer 10 and the fiber layer 30 is significantly lowered, resulting in a decrease in durability, and if it is greater than 0.3 mm, the thickness of the secondary barrier 1 In the process of manufacturing and construction, winding becomes difficult, resulting in a problem of deterioration in workability.

When the blocking layer 10 includes at least one of polyvinyl alcohol, ethylene vinyl alcohol, and nylon, the adhesive layer 20 may be formed using a thermoplastic polyurethane-based adhesive to adhere to the fiber layer 30. In addition, even when the blocking layer 10 includes polyethylene or polyethylene terephthalate, as described above, if at least a part of the surface of the blocking layer 10 is deposited with a metal such as aluminum or copper or an oxide thereof, a polyurethane adhesive can be used. be able to

The fiber layer 30 is disposed and laminated on the adhesive layer 20 formed on both sides of the barrier layer 10, and the fiber layer 30 is made of glass fibers, polyethylene fibers, and polyparaphenylenebenzobisoxazole fibers (PBO). , Aramid fibers (aramid) and may include one or more fibers selected from the group consisting of carbon fibers.

For example, the glass fibers may be E or S-glass, and the polyethylene fibers may be ultra-high molecular weight polyethylene fibers. The fiber layer 30 may be a mixed fiber including one or more of the aforementioned fibers.

Preferably, the fiber layer 30 may be a fabric layer containing polyethylene fibers as polymer fibers. Most preferably, the polyethylene fibers may be ultrahigh molecular weight polyethylene fibers. Ultra-high molecular weight polyethylene fibers have a molecular weight of 3.5 million to 7.5 million, and have been used in fields requiring excellent cut resistance due to high elastic modulus and tensile strength. In view of the fact that these ultra-high molecular weight polyethylene fibers have excellent tensile strength, tear strength, and light weight, a fabric layer is woven with the fibers and used as the fiber layer 30 for the secondary barrier 1, thereby providing a secondary barrier. (1) It is possible to secure the effect of improving the overall tensile strength and increasing the durability life.

When the fiber layer 30 includes polyethylene fibers, the adhesive layer 20 preferably uses the polyethylene-based adhesive as described above, and among glass fibers, polyparaphenylene benzobisoxazole fibers, aramid fibers, and carbon fibers, In the case of including at least one, a conventional polyurethane-based adhesive may be used.

In the liquefied gas storage tank according to an embodiment of the present invention, a secondary insulation wall fixed to a hull, a secondary barrier, a primary insulation wall, and a primary barrier may be sequentially arranged.

The insulating wall constitutes a wall surface of the liquefied gas storage tank and provides insulation for the liquefied gas stored in the liquefied gas storage tank by including a heat insulating material. The secondary insulation wall may be constructed so that at least one surface is fixed to the hull of the liquefied gas carrier, and the secondary barrier 1 may be disposed on the insulation wall. A secondary barrier 1 including RSB and FSB may be disposed on the insulating wall in a bonded form.

Specifically, the RSB may be disposed on the insulating wall through an adhesive layer, and the FSB may be disposed on the RSB through an adhesive layer.

RSB may be provided to cover the upper surface of the insulating wall to provide liquid tightness. The FSB may be provided to cover gaps between a plurality of RSBs respectively provided on a plurality of insulating walls to provide airtightness.

The RSB and FSB of the secondary barrier (1) may be determined according to the shape and size of the applied liquefied gas storage tank and the shape and size of the insulation wall, and may be a wide plate or a narrow and long band, but is not limited thereto , the shape and size of the RSB and FSB are not necessarily identical to each other.

3 is a conceptual diagram showing an apparatus 100 for manufacturing a secondary barrier 1 according to an embodiment of the present invention.

The apparatus 100 for manufacturing the secondary barrier 1 may include a barrier layer roll 110, a fiber roll 120, an adhesive film roll 130, a roll press 140, a heating furnace 150, and the like. . Using the device 100, the secondary barrier 1 can be continuously manufactured.

The blocking layer 10 may be supplied in a form wound around the blocking layer roll 110, and at least a portion of the blocking layer roll 110 may be deposited with a metal. The fiber layer 30 including polyethylene fibers may be supplied in a form wound around each fiber layer roll 120 . Each roll may be disposed so that the fiber layer 30 is laminated on both sides of the barrier layer 10, and the adhesive layer 20 is wound around the roll 130 in the form of a film and supplied before the fiber layer 30 is disposed. can The adhesive film roll 130 may be supplied so that the adhesive film is disposed between the barrier layer 10 and the fiber layer 30 .

Although not shown, the fiber layer 30 is corona-treated by passing it between electrodes where a high-frequency and high-voltage output is applied and corona discharge occurs, or the surface of the fiber layer 30 is plasma-treated using various reactive gases, and then the blocking layer 10 And it can be provided to be laminated together with the adhesive layer (20). By increasing the low surface energy of polyethylene through the surface treatment of the fibrous layer 30 and then adhering to the adhesive layer 20, the adhesive strength to the barrier layer 10 can be further increased.

After the adhesive layer 20 is formed on both sides of the barrier layer 10, the fibrous layer 30 is placed and pressed by the roll press 140 at the same time, and the secondary barrier 1 is manufactured through the heating furnace 150. can

4 is a conceptual diagram showing an apparatus 200 for manufacturing a secondary barrier 1 according to another embodiment of the present invention.

The apparatus 200 for manufacturing the secondary barrier 1 may include a barrier layer roll 210, a fiber roll 220, an adhesive injection tank 230, a roll press 240, a heating furnace 250, and the like. . As in the above-described embodiment, the secondary barrier 1 can be continuously manufactured using the device 200 .

Hereinafter, differences from the previous embodiment will be mainly described, and common contents will be replaced with the contents of the previous embodiment.

As described above, the adhesive injection tank 230 stores the adhesive suitable for the polyethylene fiber fabric having the difficult-to-adhesive property, and then supplies the adhesive according to the unwinding speed of the barrier layer 10 according to the rotation of the barrier layer roll 210 to form an adhesive layer. (20).

After the adhesive layer 20 is formed on both sides of the barrier layer 10, the fibrous layer 30 is placed and pressed by the roll press 240 at the same time, and the secondary barrier 2 is manufactured through the heating furnace 250. can

As such, the present embodiment provides devices 100 and 200 for continuously manufacturing the secondary barrier 1 including the adhesive layer 20 and a manufacturing method using the same.

Example. Preparation of secondary barrier including polymer barrier layer and polyethylene fiber layer and confirmation of physical properties

Hereinafter, a secondary barrier is prepared through the same process as in FIG. 3, and tensile strength (UTS; Ultimate Tensile Strength), elongation (elongation in UTS), elasticity at room temperature (23 ° C) and cryogenic temperature (-170 ° C) conditions Modulus and shear strength were confirmed and shown in Table 2 below. An ethylene vinyl alcohol film having a thickness of 100 μm was used as a barrier layer, LLDPE films were laminated on both sides of the film, and then a fiber layer made of ultrahigh molecular weight polyethylene fibers was laminated. The laminate was injected into a heating furnace and heated to 130° C. to prepare a secondary barrier.

As a comparative example, a conventional secondary barrier including an aluminum metal barrier layer and a glass fiber layer was used. For Comparative Example, the warp portion and the weft portion of the glass fiber layer woven in the secondary barrier were measured and shown, respectively.

Example comparative example 23℃ -170℃ 23℃ -170℃ Warp Woof Warp Woof Tensile strength (MPa) 374 388 252 219 309 299 Elongation (%) 8.7 6.8 4.47 4.94 4.35 4.71 Modulus of elasticity (GPa) 4.3 5.7 23.5 20.6 23.3 20.2 Shear strength (MPa) 4.5 7 13.0 12.7 16.6 19.7

The secondary barrier to be applied to the liquefied gas storage tank is required to have a tensile strength of about 172 MPa at 23 ° C and about 235 MPa or more at -163 ° C. The secondary barrier according to this embodiment has approximately 217% better tensile strength at 23 ° C and approximately 165% better tensile strength at -170 ° C than the reference value, compared to having a tensile strength approximately 127% to 150% better than the reference value. It was found to be superior to the example.

In addition, the secondary barrier to be applied to the liquefied gas storage tank preferably has an elongation of 2% or more under the conditions where the temperature and tensile strength are applied. The secondary barrier according to this embodiment exhibited an elongation of about 7 to 9%, and was confirmed to be superior to the comparative example showing an elongation of about 4 to 5%.

In addition, the secondary barrier to be applied to the liquefied gas storage tank preferably has an elastic modulus of about 20 GPa or less. The secondary barrier according to this embodiment has a lower modulus of elasticity than the secondary barrier according to the comparative example, and in particular, it was confirmed that the elastic modulus is maintained at less than 20 GPa even under cryogenic conditions, thereby exhibiting excellent tear resistance.

The shear strength (MPa) of the secondary barrier according to this embodiment was found to be lower than that of the comparative example. This is a result of the use of glass fibers and metal barriers that are easy to adhere to the secondary barrier according to the comparative example, and considering that the shear strength condition for application to a liquefied gas storage tank should be greater than about 3.5 MPa, this embodiment It can be seen that the secondary barrier according to is at a level suitable for practical application.

As described above, in this embodiment, excellent tear resistance and corrosion resistance can be secured compared to the metal barrier layer by using a polymer having a relatively low specific gravity for the barrier layer 10, in which a conventional metal material was used. In addition, the gas barrier properties of the barrier layer 10 may be improved by depositing a relatively thin metal on a portion of the barrier layer 10 including a polymer. Through this, it is possible to achieve a weight reduction of the secondary barrier including the blocking layer 10, thereby improving installation workability of the secondary barrier and operational efficiency of the ship.

Although the present invention has been described in detail through specific examples, this is for explaining the present invention in detail, the present invention is not limited thereto, and within the technical spirit of the present invention, by those skilled in the art It will be clear that the modification or improvement is possible.

Of course, the present invention is not limited to the above-described embodiment, and may include a combination of the above embodiments or a combination of at least one of the above embodiments and known technology as another embodiment.

Simple variations or modifications of the present invention all fall within the scope of the present invention, and the specific protection scope of the present invention will be clarified by the appended claims.

1: secondary barrier 10: barrier layer
11: adhesive layer 12: fiber layer
20: adhesive layer 30: fiber layer
100, 200: Secondary barrier manufacturing device
110, 210: barrier layer roll
120, 220: fiber layer roll
130: adhesive film roll 230: adhesive injection tank
140, 240: roll press
150, 250: heating furnace

Claims (7)

A primary barrier forming a liquefied gas storage space, a primary insulation wall provided outside the primary barrier, and a secondary barrier provided outside the primary insulation wall to prevent leakage of liquefied gas; As a secondary barrier used in a liquefied gas storage tank including a secondary insulation wall provided on the outside of the secondary barrier,
A barrier layer comprising at least one polymer selected from the group consisting of polyethylene, polyethylene terephthalate, polyvinyl alcohol, ethylene vinyl alcohol and nylon; and
Including a fiber layer laminated on both sides of the blocking layer,
The secondary barrier, wherein the fibrous layer is fixed by an adhesive layer. According to claim 1,
The polymer has a density of 0.9 to 1.7 g/cm ³ , the secondary barrier. According to claim 1,
The blocking layer,
A secondary barrier, wherein one or more metals or metal oxides selected from aluminum, copper, and oxides thereof are deposited on at least a portion thereof. According to claim 1,
The fibrous layer,
A secondary barrier comprising at least one fiber selected from the group consisting of glass fiber, polyethylene fiber, polyparaphenylene benzobisoxazole fiber, aramid fiber and carbon fiber. According to claim 4,
The fiber layer includes polyethylene fibers,
The second barrier, wherein the adhesive layer includes polyethylene and includes a thermoplastic polyethylene-based compound. According to claim 5,
The adhesive layer is
A secondary barrier comprising at least one of linear low-density polyethylene and ethylene vinyl acetate. According to claim 6,
The adhesive layer is
Has a melting point lower than the melting point of the fibrous layer,
The melting point of the adhesive layer is 90 to 120 ℃, the secondary barrier.

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