A support strap for use in a cryogenic storage vessel for supporting the inner shell from the outer shell with a minimum heat leak is presented. The compound suspension strap is made from a unidirectional fiberglass epoxy composite material with an ultimate tensile strength and fatigue strength which are approximately doubled when the material is cooled to a cryogenic temperature

Vorreiter, J. W.

English

NASA Technical Reports Server

United States Patent 1191 
Vorreiter 
[111 4,184,609 
1451 Jan. 22, 1980 
[54] CRYOGENIC CONTAINER COMPOUND 
[75] Inventor: John W. Vorreiter, Sunnyvale, Calif. 
[73] Assignee: The United States of America as 
SUSPENSION STRAP 
represented by the Administrator of 
the National Aeronautics and Space 
Administration, Washington, D.C. 
[21] Appl. NO.: 935,827 
[22] Filed: Aug. 22, 1978 
[51] Int. C l . 2  .............................................. B65D 25/18 
[52] U.S. Cl. .................................... 22W445; 220/423; 
220/901 
[58] Field of Search ............... 220/445, 448, 437, 439, 
220/420,425,901,421,423 
1561 References Cited 
U.S. PATENT DOCUMENTS 
1,866,517 7/1932 Heylandt ......................... 220/901 X 
2,592,974 4/1952 Sulfrian ............................ 220/901 X 
2,722,336 11/1955 Wexler et al. ................... 220/445 X 
2,814,410 11/1957 Hansen ................................. 220/445 
2,823,822 2/1958 Altman ................................. 220/425 
2,864,527 12/1958 Altman et al. ................... 220/445 X 
2,926,810 3/1960 Yeager ............................. 220/421 X 
3,021,027 2/1962 Claxton ................................ 220/437 
3,115,983 12/1963 Wissmiller ........................... 220/437 
3,274,788 9/1966 Hoffman et al. ................. 220/423 X 
3,764,036 10/1973 Dale et al. ....................... 220/901 X 
Primary Examiner-Allan N. Shoap 
.Attorney. Agent, or Firm-Darrell G. Brekke; John R. 
Manning; Armand McMillan 
ABSTRACT 
The present invention is directed to a support structure 
formed from a compound strap consisting of two or 
more links of different thicknesses. More particularly, 
the compound strap includes a thinner link which is 
connected to the cool end of the inner storage tank's 
outer wall and a thicker link which is connected to the 
warmer outer wall of a relatively larger outer tank 
which encloses the inner tank to provide a vacuum 
space. This vacuum space around the inner tank con- 
tains the thermal support straps preferably made of 
fiberglass epoxy resin material used to support the inner 
tank from the inner wall of the outer tank. The com- 
pound strap of the present invention minimizes the heat 
leak between the inner tank and the outer tank. 
3 Claims, 2 Drawing Figures 
https://ntrs.nasa.gov/search.jsp?R=19800010123 2020-03-21T02:23:58+00:00Z
U.S. Patent Jan. 22, 1980 
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4.184,609 
1 
CRYOGENIC CONTAINER COMPOUND 
SUSPENSION STRAP 
GOVERNMENT RIGHTS 
The invention described herein was made by an em- 
ployee of the United States Government, and may be 
manufactured and used by or for the government for 
governmental purposes without payment of any royal- 
ties thereon or therefor. 
BACKGROUND O F  THE INVENTION 
1. Field of the Invention 
The present invention is directed to a cryogenic stor- 
age vessel wherein the inner storage tank is suspended 
from the outer storage tank by means of a compound 
strap. 
2. Description of the Prior Art 
Many exemplary straps for suspending an inner tank 
from an outer tank are illustrated in the prior art. For 
example, the patent issued to Heylandt, U.S. Pat. No. 
1,866,517, discloses a double wall storage container 
having suspension chains with sections of low thermal 
leakage to support the inner container shell. The patent 
issued to Wexler et al, U.S. Pat. No. 2,722,336, discloses 
a spaced wall arrangement to store liquefied gases 
wherein one smaller inside container is supported and 
spaced within a larger outer container by a plurality of 
spacers having heat insulation properties for thermally 
insulating the liquefied gas stored within the inside con- 
tainer. 
The patents issued to Berner et al, U.S. Pat. No. 
3,230,726, and Hoffman et al, U.S. Pat. No. 3,274,788, 
disclose double-walled thermally-insulated containers 
wherein the inner product container is supported rela- 
tive to the outer insulating container by means of a low 
thermal conductivity material to minimize heat leakage. 
The Bridges patent, U.S. Pat. No. 3,623,626, discloses 
a system for supporting product tanks housed within the 
hold of a ship. The supporting elements comprise arms 
or links connected to the product tank and to the struc- 
ture of the ship which vary in accordance with a prede- 
termined straight-line contraction and expansion of the 
tank. 
In addition to the prior art discussed above, several 
other methods have been used to support the inner shell 
of a cryogenic storage vessel from the inner Surface of 
the outer shell. These methods used highly porous low 
conductivity material such as woven fiberglass or balsa 50 strap of the present invention. 
the present invention; and 
FIG. 2 illustrates an enlarged view of the compound 
vessel to support an inner storage tank from an outer 
storage tank. 
Another object of the present invention is to provide 
a compound strap which consists of two or more links 
A further object of the present invention is to provide 
a compound strap which minimizes the heat leakage 
from the outer storage tank to the inner storage tank 
and therefore reduces the boil-off rate. 
A still further object of the present invention is to 
provide a compound strap which is preferably made of 
a fiberglass epoxy resin material and wherein the thin 
strap link is connected to the inner storage tank and the 
thicker strap link is connected to the spaced inner wall 
A still further object of the present invention is to 
provide a compound strap which minimizes heat loss 
because of the graduated thickness of the compound 
strap from the inner storage tank to the outer storage 
These and other objects of the present invention are 
accomplished by constructing a compound strap prefer- 
ably of a fiberglass epoxy resin material which includes 
a thinner link connected to the inner cool storage tank 
25 and a thicker link connected to the outer warmer stor- 
age tank. A thinner inner link of the compound strap 
may be used in a cryogenic storage vessel because of the 
superior structure characteristics of the strap material at 
cryogenic temperatures. 
Other objects and further scope of applicability of the 
present invention will become apparent from the de- 
tailed description given hereinafter; it should be under- 
stood, however, that the detailed description and spe- 
cific examples, while indicating preferred embodiments 
35 of the invention, are given by way of illustration only, 
since various changes and modifications within the 
spirit and scope of the invention will become apparent 
to those skilled in the art from this detailed description. 
BRIEF DESCRIPTION OF THE DRAWINGS 
The present invention will become more fully under- 
stood from the detailed description given hereinbelow 
and the accompanying drawings which are given by 
way of illustration only, and thus are not limitative of 
FIG. 1 illustrates a cryogenic storage vessel which 
includes a plurality of compound straps according to 
5 of different thicknesses. 
10 
15 of the outer storage tank. 
20 tank. 
30 
45 the present invention, and wherein: 
wood to support the inner shell. 
The support means for connecting an inner container 
to an outer container disclosed in the prior art suffers 
DETAILED DESCRIPTION OF THE 
INVENTION 
from disadvantages which are solved by the compound Cryogenic storage vessels store liquefied gases at 
strap of the present invention. The present invention 55 very cold temperatures in the range of approximately 
sets forth a novel combination of a compound strap minus loo" C. to minus 273" C. and at moderate pres- 
consisting of two or more links of different thicknesses. sures of approximately 1 to 10 atmospheres. The liquid 
More particularly, the compound strap of the present gases stored within the vessels tend to boil away and are 
invention is used in a cryogenic storage vessel to sup- vented into the atmosphere in direct proportion to the 
port an inner storage tank from an outer storage tank. 60 amount of heat leaking into the vessel. These gases 
The compound strap of the present invention is prefera- which boil away and are vented into the atmosphere are 
bly made of a fiberglass epoxy resin material which is wasted. Therefore, to minimize the boil off of liquid 
designed to minimize heat leakage from the outer stor- gases, storage vessels are often constructed of an outer 
age tank to the inner storage tank. shell and an inner shell with a very high vacuum inter- 
65 posed therebetween. Further, the space between the 
outer shell and the inner shell is usually specially insu- SUMMARY O F  THE INVENTION 
It is an object of the present invention to provide a lated and has positioned therein a plurality of support 
compound strap which is used in a cryogenic storage members to suspend an inner shell or storage tank from 
4,184,609 
3 
the inner surface of an outer shell or storage tank. The 
compound strap of the present invention which sup- 
ports the inner shell from the inside surface of the outer 
shell is designed to minimize the heat leakage therebe- 
tween. 5 
FIG. 1 illustrates a partial cross-sectional view of a 
cryogenic container which includes an inner storage 
tank 10 which is suspended from the inner surface of an 
outer storage tank 20 by means of a plurality of com- 
pound straps 30. The space between the inner storage 10 
tank 10 and the outer storage tank 20 is highly evacu- 
ated to minimize the conduction of heat from the inner 
storage tank to the outer storage tank. As is conven- 
tional, the space between the inner storage tank and the 
outer storage tank may include a special insulation. 15 
Further, to minimize heat loss due to radiation, it is 
conventional to provide the inner shell or storage tank 
10 with a polished reflecting surface. 
The inner storage tank 10 includes a tube 14 which 
projects upwardly through the neck portion 22 of the 20 
outer storage tank 20. As illustrated in FIG. 1, the upper 
portion of the neck 22 is hermetically sealed to the tube 
14. The tube 14 includes an inlet and outlet 16 and fur- 
ther includes a bellows portion 12. The bellows portion 
12 is designed to deform to accommodate relative 25 
movement between the inner storage tank 10 and the 
outer storage tank 20 due to thermal expansion and 
contraction. 
As illustrated in FIGS. 1 and 2, the compound strap 
30 includes two links 32 and 34 which are connected 30 
together by a link bar 36. Although the drawings illus- 
trate two links which are connected together, it should 
be understood, that the present invention is not limited 
to any particular number of links. The size, shape, 
length, and number of links would be determined by the 35 
distance between the inner storage tank 10 and the inner 
surface of the outer storage tank 20. 
The compound strap 30 of the present invention is 
designed to minimize heat leakage from the outer stor- 
age tank 20 to the inner storage tank 10 by reducing the 40 
thicknesses of the link members as they progress from 
the inner surface of the outer storage tank 20 to the 
inner storage tank 10. As illustrated in FIGS. 1 and 2, 
the link 32 which is positioned adjacent the inner stor- 
age tank 10 is of approximately one-half the thickness of 45 
t6e link 34 which is positioned adjacent the inner sur- 
face of the outer storage tank 20. One end of the link 32 
is mounted on a spool 31 which is connected to a yoke 
41 by means of a connecting pin 31P. The other end of 
the link 32 is mounted on a spool 33 which is connected 
to a link bar 36 by means of a connecting pin 33P. Simi- 
larly, one end of the link 34 is mounted on a spool 35 
which is connected to a link bar 36 by means of a con- 
necting pin 35P. As illustrated in FIG. 2, the link bar 36 
extends on both sides of the spools upon which the links 
32 and 34 are positioned. Further, the other end of the 
link 34 is mounted on a spool 37 which is connected to 
a yoke 40 by means of a connecting pin 37P. 
As previously, stated, the compound strap 30 sup- 
ports the inner storage tank 10 from the inner surface of 
the outer storage tank 20. It should be understood, that 
any means of attaching the yoke 40 to the inner surface 
of the outer storage tank 20 and the yoke 41 to the inner 
storage tank 10 may be utilized in employing the com- 
pound strap of the present invention. One embodiment 
of a means for connecting the yoke 40 to the inner sur- 
face of the outer storage tank 20 would employ the use 
of a block 45 into which the yoke 40 is adapted for 
50 
5 5  
60 
65 
4 
insertion. After the yoke 40 is inserted into the block 45, 
a pin 47 may be inserted through openings in the block 
45 and the opening 42 in the yoke 40 to secure the two 
elements relative to each other. Similarly, the yoke 41 
may be attached to the inner storage tank 10 by means 
of a block 48. A pin 49 may be inserted through open- 
ings in the block 48 and through the opening 43 in the 
yoke 41 to secure the two elements relative to each 
other. 
As illustrated in FIG. 1, the link 32 is in close proxim- 
ity to the inner storage tank 10 and is approximately 
one-half the thickness of the link 34. The links 32 and 34 
and the link bar 36 are preferably constructed of a unidi- 
rectional fiberglass epoxy composite material which has 
a high strength-to-density and strength-to-thermal con- 
ductivity ratio at cryogenic temperatures. Because the 
link 32 is in close proximity to the cold temperature of 
the inner storage tank 10, the thickness of the link 32 
may be approximately one-half as thick as the link 34. 
The thickness of the link 32 may be decreased because 
the tensile strength of the unidirectional fiberglass 
epoxy composite material from which the link 32 is 
constructed increases at cryogenic temperatures. Be- 
cause of this phenomenon, the tensile strength of the 
thinner link 32 is approximately the same as the tensile 
strength of the thicker link 34 because the link 32 is at a 
colder temperature than the link 34. Further, this reduc- 
tion in thickness of the link 32 reduces the heat transfer 
from the outer storage tank 20 to the inner storage tank 
10 by approximately one-half. 
The compound strap 30 of the present invention may 
be readily utilized in a cryogenic storage vessel to sup- 
port the inner storage tank from the inner surface of the 
outer storage tank. An important feature of the present 
invention is the fact that the link of the compound strap 
positioned in close proximity to the inner storage tank 
may be of a reduced thickness when compared to the 
thickness of a link positioned adjacent the inner surface 
of the outer storage tank. This improved compound 
strap of the present invention adequately supports the 
inner storage tank from the outer storage tank with a 
minimum heat leak. As may be readily understood, the 
heat leak from the outer storage tank to the inner stor- 
age tank is reduced because of the reduced thickness of 
the link positioned adjacent the inner storage tank. Fur- 
ther, the ultimate tensile strength and fatigue strength of 
the unidirectional fiberglass epoxy composite material 
utilized in the present invention is approximately dou- 
bled when the material is cooled to a temperature of 4 
Kelvin. This increase in tensile strength and fatigue 
strength of the unidirectional fiberglass epoxy compos- 
ite material makes it possible to reduce the thickness of 
the link 32 to be approximately one-half the thickness of 
the outer link 34. 
Although the preferred embodiment of the present 
invention refers to two links positioned adjacent each 
other to support an inner storage tank from the inner 
surface of an outer storage tank, it should be readily 
understood that the strap 30 of the present invention 
may be constructed of a single strap which would be 
tapered in thickness from the outer storage tank to the 
inner storage tank. However, incorporating a single 
strap which is tapered in thickness may be difficult 
because of the method used in winding the unidirec- 
tional fiberglass epoxy composite material. 
The compound strap of the present invention may be 
readily utilized in a space cryogenic storage vessel or 
any other cryogenic storage vessel utilized to store a 
4,184,609 
6 
liquefied gas, such as a liquefied natural gas or liquid 
hydrogen. 
The invent@ being thus described, it will be obvious 
that the same way be varied in many ways. Such varia- 
tions are not to be regarded as a departure from the 5 
spirit and scope of the invention, and all such modifica- 
tions as would be obvious to one skilled in the art are 
intended to be included within the scope of the follow- 
ing claims. 
I claim: 
1. A cryogenic container comprising: 
an outer shell; 
an inner shell adapted to hold a liquid gas and P s i -  
means for suspending said inner shell from said outer 
said means for suspending said inner shell including a 
compound strap comprising at least two unidirec- 
tional fiberglass epoxy links of different thick- 
nesses, a first link of said strap having a predeter- 
mined thickness and being positioned adjacent said 
inner surface of said outer shell and a second link of 
a lesser thickness being positioned adjacent said 
inner shell. 
2, A cryogenic container according to 1, 
10 wherein said second link is approximately one-half the 
thickness of said first link. 
3. A cryogenic container according to claim 1, 
wherein the inner and outer ends of said first and second 
links are each mounted on a spool, the spool at the inner 
I5 end of said first link being interconnected to the spool at 
the outer end of said second link with link bars. 
tioned within said outer shell; and 
shell; * * * * *  
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Cryogenic container compound suspension strap

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