U.S. patent application number 12/946434 was filed with the patent office on 2011-03-10 for insulation structure of lng carrier cargo tank and method for constructing the same.
This patent application is currently assigned to SAMSUNG HEAVY IND. CO., LTD.. Invention is credited to Chang-Seon Bang, Sang-Eon Chun, Ki-Hun JOH, Bu-Gi Kim, Byoung-Jung Kim, Byung-Chul Kim, Jin-Gyu Kim, Po-Chul Kim, Dai-Gil Lee, Kwan- Ho Lee, Sang-Wook Park, Soon-Ho Yoon, Ha-Na Yu.
Application Number | 20110056955 12/946434 |
Document ID | / |
Family ID | 41691563 |
Filed Date | 2011-03-10 |
United States Patent
Application |
20110056955 |
Kind Code |
A1 |
JOH; Ki-Hun ; et
al. |
March 10, 2011 |
INSULATION STRUCTURE OF LNG CARRIER CARGO TANK AND METHOD FOR
CONSTRUCTING THE SAME
Abstract
An insulation structure of a cargo tank in an LNG carrier and a
method of constructing the insulation structure includes a first
metal foil attached and installed in between the top insulation
panel and the bottom insulation panel, a second metal foil attached
to and installed on the first metal foil that is positioned on an
upper side of a gap formed between the bottom insulation panels,
and a top bridge panel attached to and installed on an upper side
of the second metal foil.
Inventors: |
JOH; Ki-Hun; (Geoje-Si,
KR) ; Chun; Sang-Eon; (Geoje-Si, KR) ; Bang;
Chang-Seon; (Geoje-Si, KR) ; Lee; Dai-Gil;
(Daejeon, KR) ; Kim; Byung-Chul; (Busan, KR)
; Kim; Bu-Gi; (Gwangju, KR) ; Kim; Jin-Gyu;
(Changwon-si, KR) ; Yoon; Soon-Ho; (Incheon,
KR) ; Park; Sang-Wook; (Gwangju, KR) ; Lee;
Kwan- Ho; (Daejeon, KR) ; Kim; Byoung-Jung;
(Sunchang-gun, KR) ; Kim; Po-Chul; (Cheongdo-gun,
KR) ; Yu; Ha-Na; (Mungyeong-si, KR) |
Assignee: |
SAMSUNG HEAVY IND. CO.,
LTD.
Seocho-gu
KR
|
Family ID: |
41691563 |
Appl. No.: |
12/946434 |
Filed: |
November 15, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
PCT/KR2009/003310 |
Jun 19, 2009 |
|
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12946434 |
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Current U.S.
Class: |
220/560.12 ;
156/153; 156/280; 156/60; 216/35 |
Current CPC
Class: |
F17C 2221/033 20130101;
F17C 3/027 20130101; F17C 2223/0161 20130101; F17C 2203/0643
20130101; F17C 2270/0105 20130101; F17C 2203/0646 20130101; F17C
2270/0168 20130101; F17C 2270/0107 20130101; F17C 2203/0663
20130101; Y10T 156/10 20150115; F17C 2209/227 20130101; F17C
2203/035 20130101; B63B 25/16 20130101; F17C 2260/033 20130101;
F17C 2203/0358 20130101; F17C 2223/033 20130101 |
Class at
Publication: |
220/560.12 ;
156/60; 156/153; 156/280; 216/35 |
International
Class: |
F17C 1/12 20060101
F17C001/12; B32B 37/02 20060101 B32B037/02; B32B 38/10 20060101
B32B038/10; B32B 38/08 20060101 B32B038/08 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 19, 2008 |
KR |
10-2008-0057795 |
Jun 18, 2009 |
KR |
10-2009-0054580 |
Claims
1. An insulation structure of a cargo tank of an LNG carrier having
a secondary barrier of a top insulation panel and bottom insulation
panels, comprising: a first metal foil attached and installed in
between the top insulation panel and the bottom insulation panels;
a second metal foil attached to and installed on the first metal
foil at an upper side of a gap formed between the bottom insulation
panels; and a top bridge panel attached to and installed on an
upper side of the second metal foil.
2. The insulation structure of claim 1, wherein the first metal
foil and the second metal foil are made of aluminum or stainless
steel and are coated with a primer or silane.
3. The insulation structure of claim 1, further comprising a
protective films installed on adhesion parts formed on the first
metal foil and the second metal foil and preventing a foreign
substance from being attached.
4. The insulation structure of claim 1, wherein adhesive members
are pre-coated on adhesion parts formed on the first metal foil and
the second metal foil, and the insulation structure further
comprises protective films installed on the adhesive members and
preventing a foreign substance from being attached.
5. The insulation structure of claim 4, wherein the adhesive
members comprises filler particles.
6. The insulation structure of claim 4, wherein the adhesive
members comprise an adhesive film in which an adhesive is coated on
a surface of a synthetic resin film.
7. The insulation structure of claim 4, wherein the adhesive
members comprise a prepreg.
8. The insulation structure of claim 1, wherein the second metal
foil has a flat shape or a shape with an arc-shaped protruded
groove in a middle area, the groove protruded downward along a
lengthwise direction of the gap.
9. A method of constructing an insulation structure of a cargo tank
of an LNG carrier having a secondary barrier of a top insulation
panel and bottom insulation panels comprising first metal foils
attached and installed in between the top insulation panel and the
bottom insulation panels, a second metal foil attached to and
installed on the first metal foil at an upper side of a gap formed
between the bottom insulation panels, and a top bridge panel
attached to and installed on an upper side of the second metal
foil, the method comprising: attaching an adhesive film to a lower
face of the second metal foil; receiving the second metal foil at
an adhesion location where the gap is covered in such a way that
two opposite sides of the lower face of the second metal foil are
respectively in contact with an adjacent pair of the first metal
foils; installing an adhesive jig on an upper face of the second
metal foil; and attaching the second metal foil to the first metals
foil by heating and pressing the second metal foil with the
adhesive jig.
10. The method of claim 9, further comprising, prior to the
attaching of the adhesive film, surface-treating a surface of the
second metal foil.
11. The method of claim 10, wherein the surface-treating is sand
blasting or etching.
12. The method of claim 10, further comprising, between the
surface-treating of the surface of the second metal foil and the
attaching of the adhesive film, coating a primer or silane on the
surface of the second metal foil.
13. The method of claim 9, wherein the adhesive jig comprises:
pressing member configured to press the second metal foil downward;
and a heating pad installed in a lower part of the pressing
member.
14. The method of claim 13, wherein the pressing member includes an
air bag.
15. The method of claim 13, wherein the heating pad comprises a
plane heater.
16. The method of claim 9, wherein a width by which the first metal
foils and the second metal foil make contact is between 70 mm and
90 mm.
17. The method of claim 9, wherein the second metal foil is pressed
to between 50 mbar and 350 mbar and heated to between 110.degree.
C. and 140.degree. C. for 1 hour and 30 minutes to 2 hours by the
adhesive jig.
18. The method of claim 17, wherein the second metal foil is
pressed to 300.+-.1 mbar and heated to 130.+-.1.degree. C. by the
adhesive jig.
19. The method of claim 15, wherein a width and a length of the
heating pad are respectively greater than those of the second metal
foil.
20. The method of claim 19, wherein the width and the length of the
heating pad are greater than those of the second metal foil by 100
mm and 400 mm or more, respectively.
Description
PRIORITY CLAIM
[0001] This application is a continuation and claims the benefit of
priority under 35 U.S.C. .sctn..sctn.120, 365, and 371 to Patent
Cooperation Treaty Patent Application No. PCT/KR2009/003310, filed
on Jun. 19, 2009 which claims the benefit of priority to Korean
Application Nos. 10-2008-0057795, filed Jun. 19, 2008, and
10-2009-0054580, filed Jun. 18, 2009. The disclosures of the above
applications are incorporated herein by reference in their
entireties.
TECHNICAL FIELD
[0002] The present invention is related to an insulation structure
of an LNG carrier cargo tank and a method for constructing the
insulation structure of an LNG carrier cargo tank, more
specifically to an insulation structure of an LNG carrier cargo
tank and a method for constructing the insulation structure of an
LNG carrier cargo tank that can improve the sealing integrity of a
gap formed between insulation panels of the cargo.
BACKGROUND ART
[0003] LNG (liquefied natural gas) generally refers to colorless,
transparent cryogenic liquid converted from natural gas
(predominantly methane) that is cooled to approximately
-163.degree. C. and condensed to 1/600.sup.th the volume.
[0004] As LNG emerges as an energy source, efficient transportation
means have been sought in order to transport LNG from a supply site
to a demand site in a large scale so as to utilize LNG as energy.
Resulted in a part of this effort is LNG carriers, which can
transport a large quantity of LNG by sea.
[0005] LNG carriers need to be furnished with a cargo tank that can
keep and store cryogenically liquefied LNG, but such carriers
require intricate and difficult conditions. That is, since LNG has
vapor pressure that is higher than atmospheric pressure and boiling
point of approximately -163.degree. C., the cargo tank that stores
LNG needs to be constructed with materials that can withstand very
low temperature, for example, aluminum steel, stainless steel and
33% nickel steel, and designed in a unique insulation structure
that can withstand thermal stress and thermal contraction and can
be protected from heat leakage, in order to keep and store LNG
safely.
[0006] Here, the structure of a cargo tank insulation of an LNG
carrier is described below. FIG. 1 is a sectional view illustrating
the conventional cargo tank structure of an LNG carrier. As
illustrated in FIG. 1, a bottom insulation panel 10 is adhered and
fixed by way of a fixing plate 10a to an internal face of a hull 1
of an LNG carrier by epoxy mastic 13 and a stud bolt 14. Arranged
above the bottom insulation panel 10 is a top insulation panel 20,
and a rigid triplex 22 is interposed between the bottom insulation
panel 10 and the top insulation panel 20.
[0007] The rigid triplex 22, which is an insulation panel to which
the bottom insulation panel 10 and the top insulation panel 20 are
attached, is pre-manufactured in a shop and supplied into the cargo
tank to constitute a secondary barrier of the cargo tank.
[0008] When the insulation panel, such as the bottom insulation
panel 10 and the top insulation panel 20, is adhered to a cargo
tank wall, a gap 40 is formed between the adjacent bottom
insulation panels 10 so that a flat joint 18 made of a glass wool
material can be inserted in the gap 40.
[0009] Then, a top bridge panel 28 is attached in between the top
insulation panels 20 by adhering a supple triplex 26 over the rigid
triplex 22, which is already attached, with epoxy glue 24 and then
adhering the top bridge panel 28 over the supple triplex 26 with
epoxy glue 24.
[0010] The top insulation panel 20 and an upper part of the top
bridge panel 28 have a same planar surface, on which a corrugated
membrane 30, in which a plurality of corrugations are formed, is
attached as a primary barrier to complete the insulation structure
of the cargo tank of an LNG carrier.
[0011] Although a continuity-guaranteed sealed barrier has been
conventionally provided through the supple triplex 26 over the gap
40 between the bottom insulation panels 10, there has been a
problem of a possible drop in sealing effect if an adhesive
impregnated in the triplex has a high viscosity. Moreover, in case
thermal load is repeatedly exerted on the composite material of the
triplex, a crack can occur due to a difference in the coefficient
of thermal expansion between internal reinforced fiber and resin,
thereby possibly causing a gas leak.
SUMMARY
[0012] To address the above problems, an aspect of the present
invention provides an insulation structure of a cargo tank of an
LNG carrier having a secondary barrier of a top insulation panel
and bottom insulation panels, which can include: a first metal foil
attached and installed in between the top insulation panel and the
bottom insulation panels; a second metal foil attached to and
installed on the first metal foil that is positioned on an upper
side of a gap formed between the bottom insulation panels; and a
top bridge panel attached to and installed on an upper side of the
second metal foil.
[0013] Here, the first metal foil and the second metal foil can be
made of aluminum or stainless steel and can be coated with a primer
or silane.
[0014] Protective films can be installed on adhesion parts formed
on the first metal foil and the second metal foil to prevent a
foreign substance from being attached.
[0015] Alternatively, adhesive members can be pre-coated on the
adhesion parts formed on the first metal foil and the second metal
foil, and the insulation structure can also include a protective
films installed on the adhesive members and preventing a foreign
substance from being attached.
[0016] Each of the adhesive members can include filler particles,
can be an adhesive film in which an adhesive is coated on a surface
of a synthetic resin film, or can be a prepreg.
[0017] The second metal foil can have a flat shape or a shape with
an arc-shaped protruded groove in a middle area, in which the
groove is protruded downward along a lengthwise direction of the
gap.
[0018] Another aspect of the present invention provides a method of
constructing the insulation structure of a cargo tank of an LNG
carrier, which can include: attaching an adhesive film to a lower
face of a second metal foil; receiving the second metal foil at an
adhesion location where the gap is covered in such a way that two
opposite sides of the lower face of the second metal foil are
respectively in contact with an adjacent pair of first metal foils;
installing an adhesive jig on an upper face of the second metal
foil; and attaching the second metal foil to the first metal foils
by heating and pressing the second metal foil with the adhesive
jig.
[0019] The method can also include, prior to the attaching of the
adhesive film, surface-treating a surface of the second metal foil.
The surface-treating can be sand blasting or etching. The method
can also include, between the surface-treating of the surface of
the second metal foil and the attaching of the adhesive film,
coating a primer or silane on the surface of the second metal
foil.
[0020] The adhesive jig can include: pressing member configured to
press the second metal foil downward; and a heating pad installed
in a lower part of the pressing member. The pressing member can
include an air bag, and the heating pad can include a plane
heater.
[0021] The width by which the first metal foils and the second
metal foil make contact can be between 70 mm and 90 mm. The second
metal foil can be pressed to between 50 mbar and 350 mbar and
heated to between 110.degree. C. and 140.degree. C. for 1 hour and
30 minutes to 2 hours by the adhesive jig. The second metal foil
can be pressed to 300.+-.1 mbar and heated to 130.+-.1.degree. C.
by the adhesive jig. The width and length of the heating pad can be
greater than those of the second metal foil by 100 mm and 400 mm or
more, respectively.
BRIEF DESCRIPTION OF THE DRAWINGS
[0022] FIG. 1 is a sectional view illustrating a conventional cargo
tank structure of an LNG carrier.
[0023] FIG. 2 is an exploded perspective view of an insulation
structure of a cargo tank in an LNG carrier in accordance with an
embodiment of the present invention.
[0024] FIG. 3 is a sectional view of an insulation structure of a
cargo tank in an LNG carrier in an LNG carrier in accordance with
an embodiment of the present invention.
[0025] FIGS. 4 and 5 are sectional views illustrating a method of
constructing an insulation structure of a cargo tank in an LNG
carrier in accordance with an embodiment of the present
invention.
[0026] FIG. 6 is a flow diagram of a method of constructing an
insulation structure of a cargo tank in an LNG carrier in
accordance with an embodiment of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0027] Hereinafter, certain embodiments of the present invention
will be described with reference to the accompanying drawings.
[0028] FIG. 2 is an exploded perspective view of an insulation
structure of a cargo tank in an LNG carrier in accordance with an
embodiment of the present invention, and FIG. 3 is a sectional view
of an insulation structure of a cargo tank in an LNG carrier in an
LNG carrier in accordance with an embodiment of the present
invention.
[0029] In the structure of a cargo tank for cryogenic liquid in an
LNG carrier illustrated in FIGS. 2 and 3, a bottom insulation panel
110 is adhered and fixed to an internal face of a hull 100 of the
LNG carrier by an epoxy mastic 102 and a stud bolt 104, and a top
insulation panel 120 is installed over the bottom insulation panel
110 to constitute a part of a secondary barrier.
[0030] Here, a first metal foil 140 is adhered and installed in
between the bottom insulation panel 110 and the top insulation
panel 120.
[0031] The first metal foil 140 is made of flat and thin aluminum
or stainless steel, and the first metal foil 140 is adhered and
installed by an adhesive, such as epoxy glue, in the same area as
that of the bottom insulation panel 110.
[0032] Moreover, for enhanced adhesive strength, the first metal
foil 140 is coated with a primer or silane.
[0033] In addition, a protective film for preventing a foreign
substance from being attached can be installed on an adhesion part
of the first metal foil 140 over the bottom insulation panel 110
that is exposed to an upper side of a gap 130, which will be
described later. Alternatively, it is possible that an adhesive
member 144 is pre-coated on the adhesion part of the first metal
foil 140 and then a protective film 142 for preventing a foreign
substance from being attached is installed on the adhesive member
144.
[0034] The adhesive member 144 can include filler particles, and
specific examples of the filler particles include
electrically-insulating inorganic particles, such as natural
silica, synthetic silica, alumina, titanium oxide and glass, and
organic particles, such as polytetrafluoroethylene, crosslinked
acryl, benzoguanamine, crosslinked polyurethane, crosslinked
styrene and melamine.
[0035] Used for the adhesive member 144 can be an adhesive film, on
which an adhesive is coated on the surface of a synthetic resin
film, or a prepreg, which is fiber-reinforced composite. Here, the
above-described filler particles can be included in the
adhesive.
[0036] The insulation panel is pre-manufactured in a shop by
attaching the bottom insulation panel 110 to the top insulation
panel 120 with the first metal foil 140 in between.
[0037] The insulation panel is adhered to a cargo tank wall with a
space for inserting a flat joint 132 of a glass wool material in
between the gaps 130. For sealing continuity, a second metal foil
150 is adhered to the first metal foil 140 on the bottom insulation
panel 110 that is exposed to the upper side of the gap 130.
[0038] The second metal foil 150 is made of a plate-shaped metallic
material, such as aluminum or stainless steel, and can be made to
have a flat shape. Alternatively, as illustrated, a middle section
of the second metal foil 150 can be formed with an arc-shaped
protruded groove 151, which is protruded toward the bottom along
the lengthwise direction of the gap 130, to cope with thermal
contraction. The metal foil 150 is installed in such a way that the
protruded groove 151 faces the flat joint 132.
[0039] The second metal foil 150 can be coated with a primer or
silane for improved adhesive strength, and a protective film 152
for preventing a foreign substance from being attached can be
installed on an adhesion part formed on a surface of the second
metal foil 150. Alternatively, an adhesive member 154 can be
pre-coated on the adhesion part of the second metal foil 152, and
then the protective film for preventing a foreign substance from
being attached can be installed on the adhesive member 154.
[0040] Filler particles can be included in the adhesive member 154.
Used for the adhesive member 154 can be an adhesive film, on which
an adhesive is coated on the surface of a synthetic resin film, or
a prepreg, which is fiber-reinforced composite.
[0041] Then, a top bridge panel 160 is attached over the second
metal foil 150 by use of, for example, epoxy glue.
[0042] An upper part of the top insulation panel 120 and an upper
part of the top bridge panel 160 have a same planar surface, on
which a corrugated membrane 170 is attached as a primary barrier to
complete the insulation structure of the cargo tank.
[0043] The insulation structure of an LNG carrier cargo tank having
the above structure functions as follows.
[0044] Referring back to FIG. 3, a plurality of stud bolts 104 are
installed on an internal face of the hull 100 by use of resistance
welding or a separate stud gun.
[0045] Then, a second barrier panel, which is constituted by the
bottom insulation panel 110 and the top insulation panel 120, are
fixed to the hull 100.
[0046] Here, the flat joint 132 is inserted and installed in the
gap 130 between the bottom insulation panel 110 and another bottom
insulation panel 110.
[0047] Then, the protective film 142 is removed from the first
metal foil 140 that is on the bottom insulation panel 110 exposed
to the top side of the gap 130, and the second metal foil 150 is
attached using the adhesive of the coated adhesive member 144 or
the adhesive film.
[0048] Here, the protective film 152 is also removed from the
adhesion part of the second metal foil 150, and the second metal
foil 150 is adhered with the adhesive member 144 of the first metal
foil 140 by using the adhesive 154 of the coated adhesive member
154 or the adhesive film. Here, the protruded groove 151 of the
second metal foil 150 is installed to face the flat joint 132 of
the gap 130, thereby absorbing the thermal deformation of expansion
and contraction to prevent a drop in sealing integrity.
[0049] Then, epoxy glue is coated on an upper side of the second
metal foil 150, and the top bridge panel 160 is attached. Then, the
corrugated membrane 160, in which a plurality of corrugations are
formed, is attached as the primary barrier over the top insulation
panel 120 and the top bridge panel 150 by way of an anchor strip
(not shown), to complete the insulation structure of the cargo
tank
[0050] Hitherto, the insulation structure of a flat area of the
cargo tank has been described, but the insulation structure of
corner areas of the cargo tank, which are not illustrated, needs to
be constructed more rigidly that that of the flat area. It is also
possible to apply the insulation structure of the cargo tank in the
LNG carrier in accordance with an embodiment of the present
invention, which uses the first metal foil 140 and the second metal
foil 150, in the corner areas of the cargo tank.
[0051] Therefore, the present invention can prevent thermal
deformation and improve sealing integrity by interposing the first
metal foil 140 made of a metallic material between the bottom
insulation panel 110 and the top insulation panel 120 instead of a
triplex made of a composite material, which can cause a crack and
result in a gas leak due to the difference in coefficient of
thermal expansion between internal reinforced fiber and resin, and
by installing the second metal foil 150 on the first metal foil 140
that is on the upper side of the gap 130.
[0052] FIGS. 4 and 5 are sectional views illustrating a method of
constructing an insulation structure of a cargo tank in an LNG
carrier in accordance with an embodiment of the present invention,
and FIG. 6 is a flow diagram of a method of constructing an
insulation structure of a cargo tank in an LNG carrier in
accordance with an embodiment of the present invention. The method
of constructing an insulation structure of a cargo tank in an LNG
carrier in accordance with an embodiment of the present invention
will be described with reference to FIGS. 4 to 6.
[0053] Referring to FIGS. 4 to 6, an adhesive film 184 is adhered
to a lower face of the second metal foil 150 (S20). As described
above, a film of a synthetic material that is coated with an
adhesive can be used as the adhesive film 184.
[0054] Prior to attaching the adhesive film 184 on the lower face
of the second metal foil 150, foreign substances or corrosion can
be removed from the lower face of the second metal foil 150, and
the second metal foil 150 can be surface-treated, for better
adhesion (S10). The surface treatment can be performed by, for
example, sand blasting or etching.
[0055] After the lower face of the second metal foil 150 is
surface-treated (S10), and before the adhesive film 184 is attached
(S20), the lower face of the second metal foil 150 can be coated
with a primer or silane for better adhesion.
[0056] The second metal foil 150, to which the adhesive film is
attached, is received at an adhesion location, and then an adhesive
jig 190 is installed over the second metal foil 150 (S30).
[0057] The adhesion location of the second metal foil 150 is where
the gap 130 (shown in FIG. 3) formed in between a pair of the
adjacent bottom insulation panels 110 is covered in such a way that
two sides of the lower face of the second metal foil 150 are in
contact with a pair of the adjacent first metal foils 140.
[0058] The adhesive jig 190 includes a pressing member 193, which
can press down the second metal foil 150, and a heating pad 191,
which is installed in a lower part of the pressing member 193.
Here, an air bag 192 can be included in the pressing member 193.
The heating pad 191 can have a lower end part that is flat, and can
be built in with a heating coil or a plane heater such as a ceramic
heater, which is not illustrated.
[0059] After the adhesive jig 190 is installed on an upper face of
the second metal foil 150, the temperature and pressure to be
applied to the second metal foil 150 is set in such a way that the
temperature and pressure are appropriate for the properties of the
adhesive film 184 (S40). Then, the second metal foil 150 is heated
and pressed by the adhesive jig 190 in accordance with the set
value (S50).
[0060] The width and length of the heating pad 191 are formed to be
greater than those of the second metal foil 150 in order to have
the second metal foil 150 heated and pressed uniformly. When the
heating pad 191 is installed on the upper face of the second metal
foil 150, edges of the heating pad 191 are made to protrude out of
the second metal foil 150.
[0061] According to an experiment, the second metal foil 150 was
uniformly heated and pressed when the edges of the heating pad 191
were protruded by 50 mm in both of its widthwise directions and by
200 mm in both of its lengthwise directions. Therefore, it is
preferable that the width and length of the heating pad 191 are
greater than those of the second metal foil 150 by 100 mm and 400
mm or more, respectively.
[0062] Here, if the air bag 192 is used with the pressing member
193, uniform pressure can be exerted on the heating pad 191, and
thus any deviation in the pressure exerted on the second metal foil
150 can be prevented. As a result, the heat and pressure exerted on
the second metal foil 150 become uniform, and the adhesive film 184
can be uniformly attached.
[0063] According to an experiment, a good adhesion effect by the
adhesive film 184 was observed when the second metal foil 150 was
heated to between 110.degree. C. and 140.degree. C. and pressed to
between 50 mbar and 350 mbar for 1 hour and 30 minutes to 2 hours
by the adhesive jig 190. Particularly, a maximum adhesion effect
was observed when the heating temperature was 130.+-.1.degree. C.
and the pressure was 300.+-.1 mbar.
[0064] After the second metal foil 150 has been heated and pressed
for a certain period of time, the adhesive jig 190 is released
(S60). That is, the adhesive jig 190 is separated from the second
metal foil 150. A test is performed to check whether the first
metal foil 140 and the adhesion part of the second metal foil 150
are sufficiently tightly sealed (S70).
[0065] If the test result shows that the first metal foil 140 and
the second metal foil 150 are poorly adhered, the adhesion part is
repaired. That is, a new adhesive film 184 is adhered to the second
metal foil 150, and then the second metal foil 150 is received
again at the adhesion location.
[0066] If the test result shows that the first metal foil 140 and
the second metal foil 150 are properly adhered to have sufficient
sealing integrity, the top bridge panel 160 (shown in FIG. 3), the
corrugated membrane 170 (shown in FIG. 3), etc. are installed over
the second metal foil 150 to complete the construction of the
insulation structure.
[0067] For reference, sufficient sealing integrity was observed
when the width by which the first metal foil and the second metal
foil made contact was between 70 mm and 90 mm.
[0068] Although the adhesive member 144, 154 (shown in FIG. 3)
described above can be used instead of the adhesive film 184, the
adhesion part between the first metal foil 140 and the second metal
foil 150 can be formed with a uniform thickness by using the
adhesive film 184, making the sealing integrity uniform in the
adhesion part.
[0069] Moreover, since the adhesive film 184 can be pre-attached to
the second metal foil 150 when the adhesive film 184 is supplied to
a construction site, it is possible to speed up the
construction.
[0070] Although an insulation structure of a cargo tank in an LNG
carrier and a method of constructing the insulation structure in
accordance with an embodiment of the present invention have been
described hitherto, it shall be apparent that the present invention
is not restricted by the presented embodiment and can be readily
presented in another embodiment by a person skilled in the art to
which the present invention pertains by supplementing, modifying,
deleting and/or adding any of the elements within the same
technical ideas. However, such modified or permutated embodiment
shall be also included in the appended claims.
* * * * *