U.S. patent application number 11/923787 was filed with the patent office on 2008-05-01 for storage tank containment system.
This patent application is currently assigned to ALTAIR ENGINEERING, INC.. Invention is credited to Thomas Lamb, Mohan Parthasarathy, Regu Ramoo.
Application Number | 20080099489 11/923787 |
Document ID | / |
Family ID | 39325452 |
Filed Date | 2008-05-01 |
United States Patent
Application |
20080099489 |
Kind Code |
A1 |
Ramoo; Regu ; et
al. |
May 1, 2008 |
STORAGE TANK CONTAINMENT SYSTEM
Abstract
A storage tank containment system including a cubic-shaped tank
having an outer shell having cylindrical walls and an internal
cross brace interconnecting the cylindrical walls for the efficient
storage and transportation of large quantities of fluid, for
example, liquid natural gas.
Inventors: |
Ramoo; Regu; (Troy, MI)
; Parthasarathy; Mohan; (Macomb, MI) ; Lamb;
Thomas; (Lynnwood, WA) |
Correspondence
Address: |
YOUNG & BASILE, P.C.
3001 WEST BIG BEAVER ROAD, SUITE 624
TROY
MI
48084
US
|
Assignee: |
ALTAIR ENGINEERING, INC.
Troy
MI
|
Family ID: |
39325452 |
Appl. No.: |
11/923787 |
Filed: |
October 25, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60854593 |
Oct 26, 2006 |
|
|
|
Current U.S.
Class: |
220/565 ;
29/428 |
Current CPC
Class: |
F17C 2260/018 20130101;
F17C 2203/013 20130101; F17C 2209/234 20130101; F17C 2221/033
20130101; F17C 2270/0105 20130101; F17C 2209/221 20130101; F17C
2203/0646 20130101; F17C 2201/052 20130101; F17C 2201/0147
20130101; F17C 2270/0107 20130101; B65D 88/10 20130101; F17C
2203/012 20130101; B63B 25/16 20130101; F17C 2260/013 20130101;
F17C 2203/014 20130101; F17C 2223/0161 20130101; B63B 25/14
20130101; Y10T 29/49826 20150115; F17C 1/002 20130101; F17C
2203/0648 20130101; F17C 2205/0192 20130101; F17C 2201/0157
20130101; F17C 2205/0157 20130101; F17C 2203/0639 20130101 |
Class at
Publication: |
220/565 ;
29/428 |
International
Class: |
B65D 90/12 20060101
B65D090/12 |
Claims
1. A storage tank comprising: an outer shell defining six
interconnected tank sides defining an interior storage chamber; a
cross brace positioned between the six sides and interconnecting at
least four of the six sides.
2. The storage tank of claim 1 wherein the outer shell is cubical
in shape and comprises twelve substantially identical
cylindrically-shaped walls that each connect to the cross brace and
four of the adjacent cylindrical walls.
3. The tank of claim 2 further comprising eight spherical end caps,
each end cap positioned at one of eight corners of the cubical tank
sealingly connecting to three of the adjacent cylindrical side
walls.
4. The tank of claim 1 wherein the cross brace further comprises a
column connected to two opposing sides of the tank defining a top
side and bottom side of the tank, the cross brace further having a
first and a second side bracket connected to the column and
angularly positioned with respect to one another, the column and
the first and second side brackets each connecting to a different
of the six sides of the outer shell.
5. The tank of claim 4 further comprising four side extensions,
each extension extending axially outward from one of the cross
brace side brackets for connection to a bulkhead of a ship or
transportation vehicle.
6. An improved cubic storage tank for use in a ship or
transportation vehicle, the storage tank including twelve
interconnected cylindrical walls and eight spherical end caps
defining six sides of the cubic tank and an interior storage
chamber, the improved storage tank comprising: a cross brace
positioned between the six sides and interconnecting all six sides
of the cubic tank.
7. The improved tank of claim 6 wherein the cross brace further
comprises a column connecting two of the six sides defining a top
side and a bottom side of the tank, and a first and a second side
brace angularly positioned relative to one another and connected to
the column and adjacent sides of the tank.
8. The improved tank of claim 7 wherein each side brace includes a
top plate, a bottom plate and an inner wall.
9. The improved tank of claim 7 further comprising a base plate
connecting to a lower portion of the cross brace column for
connection of the tank at the bottom side to a bulkhead of a
transportation vehicle.
10. The improved tank of claim 7 wherein at least two of the side
braces includes a brace extension extending axially outward from
the tank side for connection of the tank to an adjacent bulkhead of
a transportation vehicle.
11. The improved tank of claim 10 wherein each extension includes
four side reinforcements extending axially and radially outward
from the side brace and connecting to an adjacent cylindrical
wall.
12. The improved tank of claim 9 wherein at least one side brace
comprises at least two side extensions on opposing ends, each
extension including a beveled surface for lateral supporting
connection of the tank to the bulkhead.
13. A method of fabricating a cubic storage tank comprising the
steps of: providing twelve substantially identical cylindrical
walls interconnecting to one another at their edges defining six
sides of the tank and an interior storage chamber; and providing a
cross brace positioned between the six sides and connecting to each
of the six sides.
14. The method of claim 13 further comprising the step of providing
eight spherically shaped end caps, each end cap attached to three
adjacent cylindrical walls to form a sealed tank for the storage of
fluids.
15. The method of claim 13 further comprising the step of providing
four extensions connected to the cross brace for supporting the
tank on bulkheads in a ship or transportation vehicle.
16. The method of claim 15 further comprising the step of providing
four side reinforcements extending axially and radially outward
from the cross brace and connecting to an adjacent cylindrical
wall.
17. The method of claim 13 further comprising the step of filling
the tank interior storage chamber with a fluid.
Description
[0001] This application claims the benefit of the provisional
patent application Ser. No. 60/854,593 for a STORAGE TANK
FABRICATION, filed on Oct. 26, 2006. This claim is made under 35
U.S.C. .sctn.119(e); 37 C.F.R. .sctn.1.78; and 65 FR 50093.
FIELD OF THE INVENTION
[0002] The invention generally pertains to storage tanks and more
particularly to storage tanks for fluids including liquids and
gases.
BACKGROUND
[0003] Industrial storage tanks used to contain liquids or
compressed gases are common and are vital to industry. Storage
tanks may be used to temporarily or permanently store fluids at an
on-site location or may be used to transport the fluids over land
or sea. Numerous inventions in the structural configurations of
fluid storage tanks have been made over the years. One example of a
non-conventional fluid storage tank having a cube-shaped
configuration and support structure is found in U.S. Pat. No.
3,944,106 to Thomas Lamb, the entire contents of the patent are
incorporated herein by reference.
[0004] There has been a progressive demand for the efficient
storage and long distance transportation of fluids such as liquid
natural gas (LNG), particularly over seas by large ocean-going
tankers or carriers. In an effort to transport fluid such as LNG
more economically, the holding or storage capacity of such LNG
carriers has increased significantly from about 26,000 cubic meters
in 1965 to over 200,000 cubic meters in 2005. Naturally, the
length, beam and draft of these super carriers have also increased
to accommodate the larger cargo capacity. The ability to further
increase the size of these super carriers, however, has practical
limits in the manufacture and use.
[0005] Difficulties have been experienced in the storage and
transportation of fluids, particularly in a liquid form, through
transportation by ocean carriers. A trend for large LNG carriers
has been to use large side-to-side membrane-type tanks and
insulation box supported-type tanks. As the volume of transported
fluid increases, the loads on the tank containment walls increases
significantly. These membrane and insulation type of tanks suffer
from disadvantages of managing the "sloshing" movement of the
liquid in the tank due to the natural movement of the carrier
through the sea. As a result, the effective holding capacity of
these types of tanks has been limited to either over 80% full or
less than 10% full to avoid damage to the tank lining and
insulation. The disadvantages and limitations of these tanks are
expected to increase as the size of carriers increase.
[0006] The prior U.S. Pat. No. 3,944,106 tank was evaluated for
containment of LNG in large capacities, for example, in large LNG
ocean carriers against a similar sized geometric cube tank. It was
determined that the '106 tank was more rigid using one third the
wall thickness of the geometric cube. The '106 tank further
significantly reduced the velocity of the fluid, reduced the energy
transmitted to the tank and reduced the forces transmitted by the
fluid to the tank causing substantially less deformation of the
tank compared to the geometric cubic tank.
[0007] It was further determined, however, that the '106 configured
tank did not prove suitable to handle large capacities of LNG in a
large LNG carrier environment.
[0008] Therefore, it would advantageous to design and fabricate
storage tanks for the efficient storage and transportation of large
quantities of fluids such as LNG across land or sea. It is further
desirable to provide a storage tank that is capable of being
fabricated in ship yards for large tankers that further minimizes
the number of components and minimizes the different gages or
thickness of materials that are needed for the tank. It is further
advantageous to provide a modular-type tank design which
facilitates design, fabrication and use in the field.
SUMMARY
[0009] The inventive storage tank containment system includes a
six-sided generally cube-shaped outer shell and an internal
cross-brace interconnecting at least five of the six sides of the
storage tank.
[0010] In one example, the outer shell of the tank includes twelve
substantially identical cylindrical-shaped walls interconnected to
one another at opposing edges. The outer shell further includes
eight spherical-shaped end caps closing the corners of the
cube-shaped tank. The internal cross brace structurally reinforces
the cylindrical walls and further distributes the loads due to
containment and movement of the fluid contents.
[0011] In an alternate example, a different internal cross brace is
used which includes a structurally reinforced column, angularly
opposed side brackets and end reinforcements.
[0012] In another alternate example, cross brace side extensions
are used with the internal cross brace along with a base plate to
transfer and support the loads of the tank to the fore, aft and
transverse bulkheads and tank top of the cargo hold, for example,
in a large ocean carrier.
[0013] The particular design of the tank base support and
extensions provides advantages to support the weight of the tank
and its contents and to laterally position the tank center at the
same location as the tank thermally contracts, for example, as the
low temperature liquid is loaded into it. Above each slot, a
locking plate may be provided to prevent the extension from moving
out of the mounting slot in a ship due to motion in heavy seas.
[0014] Other applications of the present invention will become
apparent to those skilled in the art when the following description
of the best mode contemplated for practicing the invention is read
in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] The description herein makes reference to the accompanying
drawings wherein like reference numerals refer to like parts
throughout the several views, and wherein:
[0016] FIG. 1 is schematic perspective view of an example of a
stand alone tank containment system;
[0017] FIG. 2 is partial schematic of the tank in FIG. 1 with the
exemplary spherical end caps removed showing part of the internal
tank;
[0018] FIG. 3 is a perspective view of one cylindrical wall
component of the tank in FIG. 2;
[0019] FIG. 4 is a partial exploded view of an alternate example of
the tank shown in FIG. 2 where the spherical ends caps are
deleted;
[0020] FIG. 5 is a perspective view of one example of an internal
cross brace;
[0021] FIG. 6 is a perspective view of an alternate example of an
internal cross brace;
[0022] FIG. 7 is a schematic perspective view of an alternate
storage tank containment system with an alternate cross brace and
cross brace side extensions;
[0023] FIG. 8 is a schematic perspective view of the bottom side of
the tank shown in FIG. 7;
[0024] FIG. 9 is a partial cut-away side view of the alternate tank
and cross brace shown in FIG. 7;
[0025] FIG. 10 is a schematic side view of the tank shown in FIG. 7
installed in a marine vessel cargo hold area;
[0026] FIG. 11 is an enlarged view of a portion of FIG. 10;
[0027] FIG. 12 is a partial top view of the storage tank shown in
FIG. 10 as viewed from direction A in FIG. 11;
[0028] FIG. 13 is a schematic side view taken from the view of
arrow B in FIG. 12 showing the side extension positioned in a slot
in a cargo hold;
[0029] FIG. 14 is a perspective view of an alternate example of the
side extensions shown in FIG. 7;
[0030] FIG. 15 is a schematic perspective view of an alternate
internal cross brace; and
[0031] FIG. 16 is a schematic side view of an example of an
ultra-large LNG carrier with four storage tanks positioned in
respective cargo holds.
DETAILED DESCRIPTION
[0032] Several examples of the storage tank containment system in
explementary uses are shown in FIGS. 1-16. Referring to FIGS. 1 and
2, the containment system includes a storage tank 10 having a
generally six-sided cubic configuration. Tank 10 includes twelve
independent, substantially identical cylindrical walls 30. The
cylindrical walls 30 are arranged to include four vertical
cylindrical walls 34 and eight horizontal cylindrical walls 40
generally arranged and configured as shown in FIG. 2. The
cylindrical walls 30 form an outer shell of tank 10 having six
sides including a top side 14, bottom side 18 and four intermediate
sides 20. The combined cylindrical walls define a interior storage
chamber 66 for containment of materials or preferably fluids
including liquids and/or gases maintained at or above atmospheric
pressure.
[0033] As best seen in FIG. 3, each cylindrical wall 30 includes a
cylindrical-shaped center portion 46 having first ends 50, adjacent
edges 52 and second ends 56. As shown in FIG. 2, each cylindrical
wall 30 interconnects with four adjacent cylindrical walls through
edges 52. In one preferred example of the construction of tank 10,
localized regions 80, where the cylindrical walls 30 connect to
each other, may be constructed of a higher gage wall thickness.
Similarly the remainder of the cylindrical walls 30 may be
constructed of lower gage plating. This may be accomplished through
tailor-welded blanks or other manufacture or assembly methods known
by those skilled in the art.
[0034] In one preferred example shown in FIG. 1, eight end caps 60
are used to sealingly close the eight corners of the cubeshaped
tank 10. End caps 60 are spherical in shape and complimentary to
the shape and orientation of the three adjacent cylindrical walls
30, namely, two horizontal cylindrical walls 46 and a vertical
cylindrical wall 34. In this configuration, the cylindrical walls
30 form a tank side opening 64 on each of the six sides of tank 10.
One or more entry ports (not shown) to access the interior storage
chamber 66 may be used to efficiently fill, extract and monitor the
tank contents.
[0035] Referring to FIG. 4, an alternate example of the outer shell
of tank 10 is shown. In this example, each of the alternate
cylindrical walls 70 includes corner portions 74 eliminating the
need for end caps 60 shown in FIG. 1.
[0036] Referring to FIG. 5, tank 10 includes an internal cross
brace 84. Internal cross brace 84 generally includes six brackets
98 angularly orientated with respect to one another for preferable
connection to each of the six sides of tank 10 defined by
cylindrical walls 30 as more fully described below. The two
vertical oriented brackets 98 form a column 100 having an upper end
104 and lower end 108 defining a first axis 110. Brackets 98 forms
a first side brace 112 defining a second axis 118 and a second side
brace 114 defining a third axis 120. The first, second and third
axes meet at a center point (not shown). In a preferred example,
the center point is positioned at approximately the center of
gravity of the tank 10. Internal cross brace 84 is positioned
between the six sides of tank 10 exterior to the internal storage
chamber 66 containing the preferred fluid. The internal cross brace
84 can be either tubular or a built up I-beam cross section (not
shown).
[0037] Internal cross brace 84, and more particularly the four ends
116 on the first side brace 112 and second side brace 114 are
connected to cylindrical walls 30 at the side openings 64 on each
of the four sides, and top and bottom as best seen in FIG. 5. The
rigid structural connections between each cylindrical wall 30 and
internal cross brace 84 provide a significantly more robust,
structurally reinforced tank 10 over prior tanks.
[0038] In a preferred example of materials for exemplary tank 10
shown in FIGS. 1-3 and 5, cylindrical walls 30, end caps 60, and
internal cross brace 84 are all manufactured from nickel steel and
have varying gage or thickness which is dependent upon the location
of the plating, size and anticipated contents of the tank to suit
the anticipated stresses in the plating or tank components. The
respective components may be connected together through continuous
seam welds along all connecting joints for strength and sealability
of the tank. It is understood that different materials, gages and
methods of connection known by those skilled in the art may be
used.
[0039] In an exemplary design as generally shown in FIGS. 1 and 2
with an internal cross brace substantially as shown in FIG. 5, a
suitable construction of a tank 10 may have the following
characteristics. For a very large tank, for example an ultra-large
LNG ocean carrier, a tank measuring approximately 36.6 meters each
in length, width and height may be used. The tank may be
manufactured from nickel steel with a modulus of 210,000 MPa and a
poison ratio of 0.3. Other materials may be used to form tank 10
including aluminum or selected steels. The contents may be liquid
natural gas (LNG) having a specific gravity of 0.5 occupying
approximately 95% of the tank 10 usable volume. In this example,
analytical testing indicated areas of higher stress in the tank 10
at the joints of the cylindrical walls 30 and region 80 of the
cylindrical walls 34 and 40 due to hydrostatic pressure loads on
the tank.
[0040] In a preferred alternate example of tank 10, as best seen in
FIGS. 2 and 6-13, alternate tank 10 design includes an alternate
cross brace 122 and side reinforcements 162. This alternate design
discloses exemplary ways for increasing the stress capabilities of
the tank and connecting the internal cross brace to an exemplary
carrier hull structure. Referring to FIGS. 2 and 6, the alternate
tank 10 includes twelve substantially identical cylindrical walls
30 and end caps 60 as previously described. The alternate cross
brace 122 comprises of a column 124 including a first wall 126 and
second wall 128 positioned approximately perpendicular to one
another defining a first axis 110. Cross brace 122 further includes
a base 132 and base reinforcements 136 connected to the lower
portion of column 124. Internal cross brace 122 further includes an
alternate first brace 137 and a alternate second brace 138 defining
a second axis 118 and a third axis 120 respectively. The first,
second and third axes converge at a center point as previously
described.
[0041] In the preferred example, each of the first 137 and second
138 braces include top and bottom plate 140 and an inner wall 142
as generally shown. Inner wall 142 may form two separate inner
walls as shown.
[0042] In a preferred example, each of the first 137 and second 138
braces may include an extension 150 extending axially outward from
inner wall 142 along second 118 and third 120 axes. Extensions 150
may each include a pair of side walls 154 and top and bottom plates
155 extending axially outward from inner wall 142 terminating at
ends 158. As shown in FIGS. 6 and 9, extension 150 may project
slightly beyond tank side 20 for connection of tank 10 to the inner
walls of a cargo hold as further described below.
[0043] In a preferred examples shown in FIGS. 6, 7 and 9, on each
of the four sides 20 of tank 10, four alternate side reinforcements
162 are rigidly attached to extensions 150 and project axially and
radially outward from second 118 and third 120 axes to
substantially compliment the curved outer surfaces of the
cylindrical walls 30 as best seen in FIG. 7. Base 132 of column 124
and reinforcements 136 serve to reinforce the bottom 18 of tank
10.
[0044] Referring to FIG. 8, alternate tank 10 may include a base
plate 170 used to structurally connect tank 10 to the floor or hull
of a cargo hold in a ocean carrier or other transportation device.
In the example, cross brace base column 124, base 132 and base
reinforcements 136 are rigidly connected to base plate 170. These
structures, along with side reinforcements 162 on bottom 18,
provide vertical and lateral support of tank bottom 18 and tank 10
in an exemplary cargo hold of a large LNG ocean carrier.
[0045] Referring to FIGS. 7, 9-12 an alternate internal cross brace
122 side extension 190 is shown differing from extensions 150 shown
in FIG. 6. In the example, alternate side extensions 190 include a
bevel 196 preferably facing toward the bottom 18 of the tank 10 and
are rigidly connected to end reinforcements 162 as previously
described. Alternate side extensions 190 are preferably located in
a slot 203 in cargo hold bulkhead 200 defined by bulkhead sides
202, angled support surface 204 and hull side 208. Bulkhead 200,
sides 202, and an angled support surface 204, allow the tank
lateral extensions 190 to slide down the bulkhead sloped surface
204 (gap shown between 196 and 204 for purposes of illustration
only) to accommodate any reduction in tank size due to thermal
contraction, for example when cold fluids are loaded in to the
tank. A vertical locking plate (not shown) may be positioned above
extensions 190 in slot 203 to prevent vertical movement of
extension 190 once installed. Alternatively, extensions 190 may be
securely attached to the bulkheads or hull.
[0046] Referring to FIG. 14, an alternate side extension of
internal cross brace 122 is shown. In the example, walls 154, as
shown in FIG. 6, are illustrated. In addition, a reinforcement 160
is added axially extending from end 144 to attach to a hull or
cargo hold bulkhead as previously described.
[0047] Referring to FIG. 15, an alternate internal cross brace 214
is illustrated. Alternate cross brace 214 preferably includes a
column 216, a first side brace 220 and a second side brace 222.
Similar to FIG. 6, cross brace 214 includes first 120, second 118
and third 120 axes. As generally illustrated, cross brace 214
includes a general I-beam construction and connects to the six
sides of the tank 10 (not shown) in a similar method as previously
described. Cross brace 214 preferably includes several
reinforcement gussets 226 (six shown in FIG. 15) and plates 230
(six shown) to reinforce the I-beam column, side braces and cross
brace as generally shown. Cross brace 214 may further connect to
the hull or bulkheads of a transportation vehicle in a manner as
further described below
[0048] Referring to FIGS. 10-13, tank 10 in an exemplary use in a
large LNG carrier, may be positioned in a cargo hold or cargo bay
area 206 of a carrier vessel 198 or other transportation vehicle.
In the preferred example, tank 10 is pre-fabricated and lowered by
crane into, or is integrally built into, a cargo hold 206. Tank 10
is vertically supported by base plate 170 which rests on the cargo
floor. Cross brace side extensions 190, including preferred beveled
196, are positioned between bulkhead sides 202 and placed in
supporting contact with bulkhead surface 204 to lock the tank in a
lateral position even as the tank overall dimensions vary with
varying cargo temperature. This support and securing design
substantially eliminates the need for any mechanical connection. In
this position, tank 10 is supported vertically and laterally in
cargo hold 206 for receipt and containment of a solid or fluid, for
example LNG, for transportation over land or sea. The structural
container tank 10 may be filled with, for example, LNG in a range
from empty up to about 95 percent of the capacity of internal
storage chamber 66.
[0049] The tank 10 may be filled with, for example, LNG to a
capacity of about 95 percent of the internal storage chamber 66. As
shown in the chart below, the volumetric efficiency of a tank 10
design (the CDTS) is compared with prior tank designs and a
proposed PRISM membrane tank system (Nobel 2005). Comparing the
tanks to a solid cube of 49,108 cubic meters, the respective
volumes and efficiencies are shown.
TABLE-US-00001 TABLE 1 COMPARISON OF TANK VOLUMETRIC EFFICENCY Tank
Type Volume Efficiency Prismatic Self-Standing 46,162 0.94 Membrane
43,706 0.88 Membrane PRISM 38,304 0.78 CDTS 40,000 0.8145 Sphere
25,713 0.5236
The table shows that the tank 10 (CDTS) is 60% more efficient than
a comparable spherical tank and an improvement over the PRISM tank
design.
[0050] Further, use of a large marine carrier or ship cargo space
was also compared. The below table shows the cargo hold space
required by each of the below tank designs compared for a 138,000
and 400,000 cubic meter carrier. The numbers in parentheses show
the percentage comparison with a membrane tank-type lining
system.
TABLE-US-00002 TABLE 2 COMPARISON OF HOLD SPACE REQUIRED BY
PRISMATIC, MEMBRANE, SPHEREICAL AND CDTS Depth Space Length Breadth
To Cover Usage CAPACITY 138,000 m.sup.3 Prismatic Self Standing 176
(95) 44 (100) 35 (103) 0.51 (106) Membrane Original 186 (100) 44
(100) 34 (100) 0.48 (100) Spherical 192 (103) 48 (109) 43 (126)
0.35 (73) CDTS 168 (90) 41 (93) 41 (121) 0.49 (102) CAPACITY
400,000 m.sup.3 Prismatic Self Standing 240 (94) 64 (100) 49 (102)
0.53 (104) Membrane Original 255 (100) 64 (100) 48 (100) 0.51 (100)
Spherical 285 (138) 67 (105) 57 (119) 0.37 (73) CDTS 230 (94) 58
(91) 58 (121) 0.52 (102)
The table shows that there are significant size reductions and an
increase in percentage of use attainable in a large marine carrier
using tank 10 over certain tank systems.
[0051] In a preferred example and method of fabrication, the
respective components of alternate tank 10 shown in FIGS. 6-13, are
preferably fabricated from nickel steel from substantially varying
gage suitable for the application and are seam welded as previously
described. It is understood that tank 10 maybe fabricated in
different sizes, and be fabricated and assembled using alternate
material and attachment techniques suitable for the particular
contents and application.
[0052] The tank 10 includes numerous other advantages over prior
tanks. Exemplary advantages of tank 10 include: flexibility on the
amount of fluid contained ranging from about 5 to about 95 percent
of the tank capacity; there is no need to stage the cargo hold to
apply insulation and lining to the cargo hold; there is no need for
significant welding of the insulation and lining securing strips
and the lining onboard a ship; the tank 10 can be installed in one
piece at the most efficient time in the ship production process;
tank 10 can be constructed of different materials and is modular in
design; tank 10 can be produced at many ship and transportation
vehicle build sites using conventional tools; tank 10 can be leak
tested before installation in a ship or transportation vehicle;
tank 10 is not subject to the level of damage from dropped items as
compared to membrane tank containment systems and tank 10 requires
a smaller base support "foot print" compared to spherical tanks
circumferential skirts. Other advantages known by those skilled in
the art may be achieved.
[0053] While the invention has been described in connection with
what is presently considered to be the most practical and preferred
embodiment, it is to be understood that the invention is not to be
limited to the disclosed embodiments but, on the contrary, is
intended to cover various modifications and equivalent arrangements
included within the spirit and scope of the appended claims, which
scope is to be accorded the broadest interpretation so as to
encompass all such modifications and equivalent structures as is
permitted under the law.
* * * * *