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Патент USA US3095116

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June 25, 1963
Filed March 16, 1961
2 Sheets-Sheet 1
.Heznrzch ZU. Bergmann
June 25, 1963
Filed March 16, 1961
2 Sheets-Sheet 2
FIG.e 4
FIG, 6
, r
/ /
iinited Setatca @arent dine
Heinrich W. Bergmann, Norman, Okla., assign’or to
Couch International Methane Limited, Nassau, Ba
hamas, a corporation of the Bahamas
Filed Mar. 16, 1961, Ser. No. 96,120
8 Claims. (Si. 22d-15)
This invention relates to the storage and transporta
Patented June 25, 1963
to the same change in dimension. Instead, it becomes
necessary to support the tank «within the thermally in
sulated space in a manner which -Will enable the tank
yfreely to expand and contract relative to the ship struc
ture. On the other hand, it is undesirable to allow the
tank to move =from a stabilized position, for example,
in response to the pitching and rolling movements of
the ship, otherwise uncontrolled forces will «be developed
which might lead to the development of undesirable and
tion of liquid having a temperature differing Widely from 10 dangerous conditions.
ambient temperature and it relates more particularly to
the over-water transportation of a low boiling liquefied
Thus it is an object of this invention to provide a
means for maintaining a tank of large capacity within a
gas, such as liquefied natural gas.
The invention will «be described with reference to the
storage space in a manner to permit freedom of move
tremely cold liquid in large volume. For one thing, it
embodying the features of this invention;
ment of the tank within the space by reason of thermal
storage of large volumes of gas in a liquefied state for 15 expansion and contraction While at the same time sta
bilizing the position of the tank within the storage
ship or over-water transportation of the natural gas from
a source of plentiful supply to an area where a deficiency
space to maintain full control of the tank during such
expansion and contraction movements or other move
exists. It will be understood that the concepts of this
invention will have application also to the storage and
ments of the space in which the tank is mounted.
transportation of other loW boiling liquefied gases or 20
More specifically, it is an object of this invention to
provide a means >for mounting a storage tank or tanks
liquids maintained at an extremely cold temperature and
of large capacity Within an insulated storage space of
that the concepts of this invention are applicable also
to other means of transportation in which the storage
a ship Without direct attachment to the ship structure
container might be subject to rocking, rolling or pitch
to enable thermal movement of the tank relative to
ing movements, in addition to the expansions and con 25 the supporting ship structure, yet with means for sta
tractions due to temperature change.
bilizing the position of the centerline of the bottom of
the tank ywithin the supporting ship structure to prevent
vFor the storage and transportation of natural gas in
large quantities, it is desirable, from the standpoint of
uncontrolled movements of the tank from a stabilized po
sition Within the ship.
space utilization, to reduce the gas to a liquefied state
whereby it is reduced about 60G-fold in volume. It is 30
These and other objects and advantages of this in
also desirable to house the liqueiied «gas in containers of
vention will hereinafter appear and for purposes of i1
large capacity with the result that it becomes impractical
lustration, but not of limitation, an embodiment of the
invention is shown in the accompanying drawings, in
to consider storage under pressure conditions departing
Widely from atmospheric pressure. Under such circum
stances, the liquefied «gas will 4be maintained in the storage 35
FIG. l is a schematic sectional elevational view of
container at about atmospheric pressure, which, for lique
a ship, in which a number of storage tanks of large
capacity are mounted in accordance with the practice of
fied natural gas composed mostly of methane, will mean
storage at a temperature of about --248° F. to about
this invention within the hold space of the ship;
_258° F., depending upon the amount of higher mo
FIG. 2 is a cross-sectional elevational view taken along
lecular weight hydrocarbons present in the liqueñed nat 40 the line 2-2 0f ~FIG. 1;
ural gas.
FIG. 3 is a perspective view partially in section of
There are a number of extremely important problems
the bottom side of a tank and supporting flooring with
presented in the storage and transportation of such ex
the elements shown in their separated relationship and
is desirable to surround the liquid storage tank or con 45
FIG. 4 is a sectional View of the tank in its mounted
tainer with an effective amount of thermal insulating
relationship on the supporting ñooring in a bottom sta
-bilized position;
material not only to minimize loss of cargo by vaporiza
tion due to heat loss into the liquid from the surround
FIG. 5 is a plan view partially in a section of a modi
ing atmosphere, but it is also desirable to protect the steel
fication in the key construction;
hull and structure of the ship or other transportation 50
FIG. 6 is a fragmentary sectional elevational view
means from the cold of the liquid, otherwise the ship
showing a further modification in the key construction;
will be subject to destruction since the steels of which
FIG. 7 is a fragmentary sectional elevational view
such ships are constructed begin to lose their strength
similar to that of FIG. 6 showing a still further modifica
and ductility at low temperatures and cracking can be
tion in the key construction; and
experienced upon reduction of the steel to a temperature 55
FIG. 8 is a plan view partially in section of a further
below _100° F.
modification in the key construction.
-For another thing, the storage tank is exposed to
Referring now to the drawings, the numeral 10 rep
extremely wide temperature `change in use which, in
resents a ship having a hull structure formed of an
the storage and transportation of liquefied natural gas,
outer steel hull 12 and an inner steel hull 14 spaced
may range from about -}-l00° F. during installation or 60 a short distance from the outer hull and interconnected
-When the tank is empty to a temperature of about »258°
therewith periodically to provide a sealed space in be
tween deiining wing tanks 16 for ballast of the ship and
F., when the tank is :filled with liquid cargo. When,
as in the usual practice, the tanks are fabricated of a
for circulation of water or the like therethrough to con
metal which is relatively insensitive to the temperature
trol the temperature of the walls forming the inner hull
change, such as aluminum or alloys of aluminum, stain 65 thereby to .protect the outer hull in the event of escape
of cold liquid to the walls of the inner hull. The inner
less or the like high nickel steels, copper, brass, etc., a
rather wide change in dimension of the tank will take
hull represents a preferred construction but it is not
place by reasons of expansions and contractions due to
essential and thus reference which will hereinafter be
temperature change. In a storage tank with a length
made to the hull structure will include a single hull as
of about 100 feet, a change of 3 or more inches in any 70 well Vas a double hull of the type described.
direction can occur. As a result, the tanke cannot be
Coiferdams 1S which extend crosswise of the ship be
rigidly tied into the ship structure which is not subjected
ytween the hull structure subdivide the hold space of the
ship into a plurality of longitudinally spaced apart sep
arated hold compartments 20. A relatively thick layer
22 of thermal insulating material is applied as a lining
to the side walls of the compartments and as a flooring
24 on the bottom wall to insulate the hold space.
ber running in the lengthwise direction, as illustrated in
FIG. 5.
The bottom 28 of the tank is provided with a keyway
5t) adapted to engage the key in fitting relationship there
in, preferably without the key extending entirely into the
keyway and without the keyway coming to rest upon the
hardwood layer 42 on the ñoor. For this purpose, the
bottom wall of the tank is provided with a pair of elon
ural gas or other extremely cold liquid. Such storage
gated angle irons 52 and 54 secured to the bottom side
tank or tanks may be of rectangular shape for fuller
utilization of the space available -in the insulated hold 10 of the tank with the upright portions 56 spaced cross
Mounted within the insulated hold space are one or more
tanks 26 of large capacity for housing the liqueñed nat
of the ship or they may be of other coniigurations in cross
section but usually they will be formed with a relatively
flat bottom wall 28 so that the bottom wall can rest on
the insulated flooring 24.
As previously pointed out,
the tanks of this invention are tanks having suflicient
wall thickness and strength for self-sul'ñciency under load
and they will be formed of a temperature insensitive,
structurally strong material which does not experience
excessive loss in strength Vor ductility when reduced to low
Wise one from the other by a distance corresponding to
the width of the ñoor key 44 so as Ito receive a portion
of the key in sliding relationship therebetween. The up
" right portions 56 of the angle irons extend downwardly
15 for a distance substantially corresponding to the thick
ness 0f the key to receive a major portion of the key
therebetween when the tank is properly positioned on the
supporting ñooring. The load is taken od of the key
and keyway construction by a pad 58 of dimensionally
20 stable material interposed between the bottom wall 28
of the tank and the top surface 4Z of the supporting floor
The Itank will be ñtted with the usual connections such
ing beyond the key and keyway construction. Such pad
as inlet pipes 30 for filling, outlet pipes 32 for the removal
which may be formed of balsa wood is dimensioned to
of liquid cargo, pressure relief valves 34 and the like
have a thickness slightly greater than the thickness of
gauges for the control of fluid flow, fluid levels and pres
sures within the tank. Usually these iittings will extend 25 the key and also slightly greater than the depth of the
keyway so that the pad and flooring will carry the entire
into the tank through a trunk 36 which projects upwardly
weight of the tank while the key and keyway will carry
from about the central portion of the tank through an
loads having a crosswise direction other than those which
aligned opening 38 in the deck 40 of the ship to a point
had been dissipated by the frictional resistance to relative
above the deck where access can be had to the iittings.
Having briefly set forth the environment, detailed de 30 movement available over the substantial area of contact
-between the bottom of the tank and its supporting sur->
scription will now be made of the means for positioning
faces. It is possible to line the inner surfaces of the up
the -tank within ,the insulated hold space without direct
right portions 56 of the metal angle irons with a butter
attachment to the ship structure whereby the tank is free
material, such as wood, in order more uniformly to dis
to move -relative to the ship structure in response to ex
pansion and contraction forces due -to temperature change, 35 tribute the crosswise loads.
yet is stabilized along a center line in a predetermined
By way of illustration with respect to the relative pro
position within the insulated hold space to militate against
portions of the described elements, a key dimensioned to
uncontrolled movements relative tothe ship in response to
have a width within the range of l2 to 24 inches and a
the pitching and rolling movements of the ship.
height of -about 2 inches will be formed with the length
As illustrated in FIGS. 3 and 4, the insulating ñoor 40 wise grained portions 46 about `1/2 inch in thickness and
24 on which the tank rests is formed of -a relatively thick
with lthe crosswise grained portion 48 of about l1/z inches
layer of a structurally strong and dimensionally stable
in thickness. The depth of the key Sti will also corre
thermal insulating material. In the illustrated embodi
spond to about 2 inches and the pad 58 located between
ment of the invention, such flooring is constructed of a
the flooring and the bottom wall of the tank will be di
relatively thick layer of balsa wood having a relatively 45 mensioned to be about 2.1/2 inches whereby to space the
flat top ply 42 of hardwood to more or less protect the
upper end of the key about 1/z inch from the bottom wall
softer and more porous balsa wood from the forces and
of the -tank and to space the far ends of the keyway
impacts to which it might otherwise be subjected during
about 1/2 inch from the hardwood flooring. It will be
installation of the tank or during use.
understood that the dimensional characteristics can be
Fixed to the top surface of the hardwood layer is an 50 varied aswell as the relative position of the longitudinally
elongated key 44 which extends lengthwise of the storage
space, preferably in lengthwise alignment with about the
grained and crosswise `grained portions making up the
center Vof the tank adapted to rest upon the supporting
The assembly to eñect a ñtting relationship between the
ñooring. The key is formed of hardwood sections with
and keyway, without exposing the keys to destructive
the grain of Athe Wood in the lower and thinner section 55 unbalanced forces which might become possible when
46 extending lengthwise of the key and with the grain
considerable play exists between the lateral edges of the
of the wood forming the upper and thicker of the sections
key and the corresponding surfaces of the keyway, can be
48 extending crosswise of -the key and in the direction
beneiited greatly by a modification in the construction of
of the more substantially rolling movements of the ship.
the continuousand preferably the keys formed of discon
Preferably the key 44 is a continuous key as long as
tinuous but aligned segments. Such modiñcation, illus
or substantially as long as the tank. However, it may beV
that because of method of construction, the floor 24 may
be formed with 4thin scabs between modular panels where
trated in FIGS. 6 and 7, include side panels 66 fixed to the
lateral edges of the key segments 60 to function as rup
turable load bearing elements. In the preferred practice,
by it becomes impractical to construct the hardwood key
the segments are deemed to have a thickness greater than
describedras a continuous key having a length correspond
the difference between the width of the key and the key
ing tothe length of Ithe tank. Thus the key 44 may be
way so that the ‘segments will extend laterally from the
fabricated of a plurality of shorter key segments 60
key members to a point beyond the upright members de
spaced lengthwise one from the other to provide an open
iining the keyways.
space .62. therebetween across which Vthe scabs may ex 70
Such additional side panels are selected of structural
tend. In such construction, it is desirable either .to cover
materials which are easily rupturable along the lines of
the key segments by a metal sheath 70 (see FÍG. 8), such
force applied vertically but which are capable of retaining
as an aluminum sheath, or it.may be desirable to inter
the forces applied laterally. Suitable material is available
commerciaily as “Panelyte” marketed by the St. Regis
connect the keys by beam 64 secured to the lateral edges
of the key segments with `the grain of the wooden meni 75 Paper Company. Such material comprises a plurality of
fibrous sheets of paper, etc. arranged in parallel relation
ship and laminated into a composite structure with a rela
tively high percentage of a somewhat brittle resin, such as
phenol formaldehyde resin, urea formaldehyde resin, mel
amine formaldehyde resin, and the like.
In response to a force aligned with the edge of the panel,
parallel with the laminations, the force elements would
easily cut through the panel, yet the panel remains ca
tiled June 24, 1958, now Patent No. 3,007,598, entitled
“Tank Construction.”
It will be understood that the concepts of this invention
will have application to the stabilization of tanks of large
capacity independent of the cargo where the tank is sub
ject to expansion and contraction characteristics differing
from that of the support and where the tank is exposed
to movements which tend to unstabilize the position of the
pable of taking lstrong forces in compression applied
against its side faces.
It will be understood that changes may be made in the
The improvement from the standpoint of ease of as
details of construction, arrangement and operation with
sembly that is derived by the use of such rupturable load
out departing from the spirit of the invention, especially as
defined in the following claims.
bearing extensions stems from the difficulty perfectly to
I claim:
align the key and keyway during installation. The result
of improper alignment between the described elements
l. In the storage and transportation of a material hav
while lowering the tank into position of use may expose
ing a temperature differing widely from ambient temper
on key segment to `substantially the entire load with the
ature, a container of large capacity having a relatively flat
possible rupture thereof. On the other hand, when such
bottom, means for mounting said container within a sup
extensions are employed, such misalignment as might oc
porting structure in a manner to stabilize the position of
cur merely results in the misaligned key portion engaging 20 the container within the ‘supporting structure while permit
the extension in a manner which would cause said key por
ting free expansion and contraction due to temperature
change, comprising a iiooring forming a part of the sup
tion to cut into the extension. This operates to stabilize
the tank to the point where it is immediately held against
porting structure having a relatively ilat top surface upon
inadvertent rocking movements as would otherwise result
which the container rests, an elongated key member ex
in progressive engagement of the key segment or segments 25 tending upwardly from the surface of the floor to extend
with possible destruction thereof.
lengthwise of the container, a pair of elongated members
In the arrangement where the extensions 67 are of such
secured to the bottom of the container in alignment with
dimension as to require the keyway members to cut into
the key member and spaced one from the other laterally
by an amount corresponding to the width of said key mem
the extensions during installation, it will be apparent that
no uncontrolled or otherwise destructive movements will 30 ber to form a keyway dimensioned slidably to receive the
be permitted. The key extensions will be cut by the key
key member therebetween when the container is properly
way to provide a snug ñtting relationship between the key
positioned within the supporting structure, and a spacer
Way and the key elements disposed therebetween.
between the bottom wall of the container and the support
ing floor dimensioned to have a thickness greater than the
It is desirable to locate the key to extend lengthwise of
the ship because »the greatest destructive forces to which 35 maximum thickness of any one of the members including
the key and keyway but less than the sum of the thick
the elements will be exposed will be the forces operating
nesses thereof whereby the key will be received within the
crosswise of the ship in response to rolling movements of
keyway without engagement with the bottom wall of the
the ship. The key and keyway construction is preferably
container and without the keyway engaging the surface of
located along the center line of the tank whereby the ex
pansion and contraction movements of the tank will take 40 the floor when in the assembled relationship.
2. In the ystorage and transportation of an extremely
place with reference to the »stabilized center line. It will
cold liquid in large volume in a tank of large capacity
be understood, however, that the key and keyway means
which is formed of a material characterized by substan
for stabilization can be located other than along the center
tial expansion and contraction due to temperature change
line of the tank to define the reference point from which
expansion and contraction movements occur.
45 and which has -a relatively flat lbottom, means for mount
Because of the relatively small forces acting to displace
ing said container within an insul-ated structure in a
the tank lengthwise in the ship, the frictional resistance to
manner to stabilize the position of the tank within the
movement under load between the bottom wall of the tank
insulated structure while permitting free expansion and
and its supporting flooring will usually be sufficient to
contraction, comprising a flooring Iforming »a part of the
stabilize the lengthwise position of the tank without addi 50 insulated structure upon which the t-ank rests, an elongat
tional stabilization means. However, it will be understood
ed key extending upwardly from the surface of the floor
that a similar single key and keyway construction can be
in lengthwise alignment -with the container, a pair of
provided to extend crosswise of the tank to stabilize the
elongated angle members fixed -to the bottom side of the
tank at a 'single reference point from which expansion and
bottom wall of the tank and spaced one yfrom the other
contraction movements will take place.
55 laterally 'by an amount corresponding to the width of
the key member -to deñne a keyway dimensioned slidably
Such reference point can also be embodied, if desired,
to receive the key member therein when the tank is
in the longitudinally extending key and keyway by iixing
properly positioned within the insulated structure, a pad
an abutment to confront a crosswise extending portion of
positioned between the bottom wall of the tank and the
the key or by dropping the ends of the keyway slightly be
yond the ends of the key to confine the ends of the key 60 floor and having a thickness greater than the maximum
thickness `of any one of the elements including the key
whereby the key can shift only a limited distance within
and keyway but less than the sum of the thicknesses
thereof whereby the key will be disposed within the key
It is also desirable to stabilize the position of the tank
Way without the key engaging the bottom Wall of the tank
at the top to minimize rocking movement of the tank re
sponsive to rolling movement of the ship. Various means 65 and without the keyway engaging the surface of the floor
when the tank is properly mounted within »the insulated
for top stabilization have been developed, one of which
is illustrated in FIG. 2 and is more fully described in my
3. A system as claimed in claim 2 in which the key
copending application tiled concurrently herewith and en
member comprises a wooden member.
titled “Stabilization Means for Tank Mounting.” Other 70
4. A structure «as claimed in cl-aim 3, in which the key
techniques are described in the Farrell et al. Patent No.
comprises a wooden laminate having one layer with the
2,954,003, the copending application of Murphy, Ser. No.
wood grain extending in the crosswise direction `and an
71,085, filed November 22, 1960, now abandoned, en
other layer with the wood grain extending in the length
the keyway.
titled “Tank Construction for Storage of Cold Material,”
wise direction, said one layel- being of greater thickness
and the copending application of Beam, Ser. No. 744,225, 75 than the other layer.
5. A system as `claimed in claim 2 in which the pad
disposed Ibetween «the bottom wall rand the floor comprises
a balsa Wood layer which extends substantially continu
ously ibetween the ñat bottom wall of the tank `and the`
relative top surface of the floor other than Within the key
and keyway portion.
6. A system as claimed in `claim 2, in lwhich the key
is ysu-bdivided into separated linearly aligned segments,
of material readily .rupturable yertioally in response to
the application of vertical force parallel to the s-ide faces
of the key, said members extending laterally from the
key and being dimensioned to project beyond the side
Walls of the key by an amount greater than the difference
'~ lbetween the width of the key and width of the keyway
thereby -to project in the path of the keyway upon in
and a sheath extending continuously over the segments
to define la continuous key therebetween,
7. A system as claimed in claim 2, in which the key is
subdivided int-o separated linearly aligned segments and
which includes elongate members extending continuously
alongside the key segments and secured thereto.
8. A system as claimed in Iclaim 2, which includes mem
bers extending laterally from the sides of the key -formed
References Cited in the tile of this patent
Henry ______________ __ Sept. 22, ,l959`
Great Britain __________ __ Feb. 27, 1952
France ;__'___.._'_ _____ __ Mar. 2S, 1960 . j
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