US3862700A

US3862700A - Low temperature liquified gas storage tank

Info

Publication number: US3862700A
Application number: US269568A
Authority: US
Inventors: Tetsuo Noma; Osamu Nagao; Ichizu Okano
Original assignee: Hitachi Zosen Corp
Current assignee: Hitachi Zosen Corp
Priority date: 1971-09-11
Filing date: 1972-07-07
Publication date: 1975-01-28
Anticipated expiration: 1992-01-28
Also published as: DK134828C; SE378900B; JPS5313041B2; NO131100C; FR2152514A1; DE2244403C3; JPS4835416A; DE2244403B2; DE2244403A1; GB1354046A; DK134828B; FR2152514B1; NO131100B

Abstract

A low temperature liquified gas storage tank having a rigid outer wall and a low temperature resistant, liquid tight inner wall formed of barrier members made of plywood, sheet metal or plastic. Joists fixed to the outer wall extend along the joints between the side edges of adjacent barrier members, are secured thereto, and the inner surface of each barrier member within the area bounded by the joists is supported by the outer surface of a pressure pad carried by the outer wall so as to permit relative thermal expanding and contracting movements between each pressure pad and the barrier member supported thereby.

Description

United States Patent Noma et al. 1 Jan. 28, 1975 [54] LOW TEMPERATURE LIQUIFIED GAS 3.339.778 9/1967 Herrenschmidt 330/15 STORAGE TANK 1233133 1311335 ilklfil '41 ll}? [75] In ento s: Tetsuo Noma; Osamu agao: c u 3:694986 /1972 Yamamoto et al. 220/ Okano, all of Osaka. Japan FORElGN PATENTS OR APPLICATIONS [73] Assgneei i Smpbmldmg and 2014.174 10/]966 Sweden 220/9 1.0 jEngmeermg Cmnpanh 8%.267 6/l962 Great Britain 220/9 LG apan [22] Filed: July 7, 1972 Primary Examiner-William l. Price Assistant ExaminerStephen Marcus PP 269,568 Attorney, Age/11,7 Firm-Farley, Forster and Farley Foreign Application Priority Data [571' ABSTRACT Sept. 11, 1971 Japan 46-70699 A low temperature quified Swmgc tank having a rigid outer wall and a low temperature resistant, liquid 2% 2 x 73 j, g tight inner wall formed of barrier members made of i 56 F 9 LG 217/65. P ywood, sheet metal or plastic. .loists fixed to the l 1 0 care 52 6 6 outer wall extend along the joints between the side I edges of adjacent barrier members, are secured 56 R f Ct d thereto, and the inner surface of each barrier member L 1 evergnces within the area bounded by the joists is supported by UNITED STATES PATENTS the outer surface of a pressure padcarried by the 67.035 7/1867 Foley 220/15 outer wall so as to' permit relative thermal expanding 2263,9 3 11/ 41 ar e -m. .220/l5 and contracting movements between each pressure 5 iigzi g t iiiiiii pad and the barrier member supported thereby. os'er..... 3,1 l2,043 ll/l963 Tucker 220/15 8 Claims, 9 Drawing Figures PATENTED JAN 2 8 I975 SHEET 10F 1' FIG.|

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PATENTEUJANZBIBIS I LOW TEMPERATURE LIQUIFIED GAS STORAGE TANK SUMMARY OF THE INVENTION The present invention relates to an improved construction for a low temperature liquified gas storage tank and more specifically to a low temperature liquified gas storage tank of a construction in which a tank inner wall, made of low temperature resistant and liquid tight barrier members, is supported by means of joists in inwardly spaced relation to a rigid outer wall of the tank.

Safety and saving of expenses in particular should be pursued for a large sized tank for storing a low temperature liquified gas, because it is necessary to ensure that the gas does not leak and that the tank does not collapse under the extremely low temperature, such as minus I62C, to which atank of this kind is subjected. It is less desirable as a matter of course, however, to use a great deal of expensive metal which is capable of withstanding such extremely low temperatures.

To attain these objectives, it is advisable to construct the tank inner wall out of barrier members, made of liquid tight plywood or sheet metal which is resistant to low temperature, inside of and insulated from a rigid tank outer wall which is made of normal steel plate, with a wooden framework supporting the inner wall on the outer one. Naturally in this case, study is invited to the tank inner wall with regard to the liquid pressure applied thereto and to the expansion and contraction thereof caused by the charging and discharging of the low temperature liquid. For example, when using liquid tight plywood panels for the tank inner wall, the plywood is required to have enough thickness to withstand the liquid pressure even though it is supported by means of joists. As thermal stress created on the plywood increases proportionally to the increment of its thickness, a very great stress is introduced at the joints thereof between adjacent panels. In a structure in which the plywood panels are fixed to the tank outer wall, a joint between panels in the same plane is balanced in stress since both sides thereof are equally stressed in opposite directions, but a joint in a corner of the tank must be of substantial construction, because it is stressed only on one side thereof. Therefore, a problem arises in that the thick plywood -is difficult to mount fixedly on the tank wall.

As is apparent from the foregoing, the tank inner wall needs the two requisites of a liquid tight nature and pressure resistivity. In order to solve this problem, this invention furnishes the inner wall with the liquid-tight nature through the use of barrier members and separately provides the pressure resistivity through a pressure resisting construction of the wall, in order to reduce the thickness of the barrier members, thus preventing great stress from arising on the barrier members clue to the temperature variation that is caused by the charging and discharging of the low temperature liquified gas. Therefore, the barrier members can be fixed firmly without wrinkling the barrier members or making the joints between them expandable, and moreover, the barrier members can bear the liquid pressure adequately.

The present invention employs pressure supporting pads fixed on the tank outer wall to support the barrier members from their back side over nearly their entire surface area, and the pads are permitted to unrestrictedly expand or contract relative to the barrier members so that the pads do not transmit their thermal expansion or contraction thereto. For the low temperature resistant and liquid tight barrier members, plain, liquid tight, and standard size plywood or sheet metal or synthetic resin plate is employed which is of low thermal stress, and the barrier member joints are fitted firmly on coupling joists fixed on the tank outer wall.

With such structure, the tank can be very simple in construction and a sharp reduction in cost can be achieved in comparison with conventional structures in which the barrier members with a great thermal stress are wrinkled or corrugated to promote the expansion or contraction thereof, and a so-called expandable construction is used for the joints thereof instead of fixing the joints firmly on the coupling joists. Moreover, in the present invention, a barrier member does not need to be thick enough to carry the liquid pressure in itself, since its surface is supported by means of the supporting pads, and for this reason, a thinner barrier member is employed for the tank inner wall to reduce the thermal stress. Thermal expansion or contraction cannot affect the fixing of the barrier member joints on the joists, because the expansion or contraction of the pressure supporting pads is not transmitted to the barrier members.

Other features and advantages of the present invention will be apparent from the following description of the preferred embodiments illustrated in the accompanying drawings.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic sectional view ofa low temperature liquified gas storage tank;

FIG. 2 is a fragmentary enlarged sectional view of a tank constructed in accordance with the-present invention;

FIG. 3 is an enlarged sectional view showing the construction of a joint between plywood barrier members;

FIG. 4 is an enlarged sectional view showing the construction of a joint between sheet metal barrier members;

FIG. 5 is a sectional view similar to FIG. 4, but showing an alternate construction of a joint between sheet metal barrier members;

FIG. 6 is an enlarged sectional view showing the construction of a joint between barrier members formed of synthetic resin plates;

FIG. 7 is a plan view of a portion of the inner wall of the tank showing a standard sized barrier member;

FIG. 8 is an enlarged sectional view showing a spot attachment of a sheet metal barrier member to a pressure pad; and,

FIG. 9 is a sectional view similar to FIG. 8, but showing an alternate construction for a barrier member of synthetic resin plate.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1, numeral 1 is a tank outer wall made of normal steel plate and is equivalent to a tank outside shell located in the earth or to a wall of the inner hull in a transporting vehicle such as a ship. Numeral 2 is a low temperature resistant and liquid tight tank inner wall, located at a necessary space for heat insulation inwardly from the tank outer wall 1. Heat insulating material 3 is inserted between this inner wall 2 and the outer wall 1.

The inner wall 2 is made of low temperature resistant and liquid tight barrier members 8 joined together, these barrier members all being planar, or a standard size, and low in thermal stress. This kind of barrier member may be plywood 5, as shown in FIG. 3, having an inner layer ofliquid tight material 4 such as resin impregnated paper or a low temperature resistant metal film; or may be, as illustrated in FIGS. 4 and 5, a material which is low in Youngs modulus and has a relatively wide elastic range such as aluminum or copper, or alternately a low temperature resistant metal sheet 6 having a low coefficient of thermal expansion, such as 36 percent nickel steel; or, may be a low temperature resistant synthetic resin plate 7, as illustrated in FIG. 6.

The joints 9 between the barrier members 8 are fixed firmly on coupling joists 10, as shown in FIG. 3 to FIG. 6, which will be described in detail later on. The coupling joists 10 are arranged in checkerboard fashion, are composed of plywood, and include legs 12 which are firmly attached to the joists 10 in places through angle pieces 11 to form a sectionally T-shaped configuration. The legs 12 are fixed to the tank outer wall 1 through angle pieces 13, as illustrated in FIG. 2.

Numeral 14 designates pressure pads each provided with a planar liquid pressure supporting surface 15 to support a barrier member 8 behind most of the surface area thereof. These pads are each made of a pad plate 16 formed of plywood and of leg plates 18 attached firmly adjacent to the perimeter of the pad plate through angle pieces 17. A pad 14 is placed between each barrier member 8 and the tank outer wall 1, and the leg plates 18 are fixed on the tank outer wall 1 through angle pieces 19. The above-mentioned liquid pressure supporting surface 15 supports each barrier member 8 so as to permit relative thermal expansion and contraction between the pressure pad 14 and the barrier member 8 supported thereby.

The manner in which the barrier member joints 9 are fixed on the coupling joists 10 is described as follows:

Referring to FIG. 3, showing plywood panels 5 used .for the barrier members 8, the plywood above the layer of liquid tight material 4 is cut away from adjacent edges 20 of each panel to a certain width to bare the liquid tight material. A strip of patching material 21 is attached to the bared portions 4a of the liquid tight material at the left and right hand sides of the adjacent edges of the panels by means of a low temperature resistant adhesive 22, and both plywood panels 5 are secured to the coupling joist 10 by driving nails or wood screws 23 through the strip of patching material 21 into the coupling joist 10 through both of the plywood panels 5. Moreover, the strip of patching material 21 and bared portions 4a liquid tight material are covered with a low temperature adhesive 24, thus completely preventing liquid from leaking through the joint 9.

FIG. 4 illustrates a coupling joist 10 and the joint 9 between low temperature resistant metal sheets 6 used for the barrier members 8, the adjacent edges of the sheets being connected by means of welding 25. Numeral 26 is a backing strip laid under the joint 9 of the sheets 6, and 27 is a refractory material such as asbestos to prevent welding heat from scorching the coupling joist 10. The sheets 6 welded at the joint 9 thereof are secured to the coupling joist 10 through the backing strip with wood screws 28 at both sides of the welded joint. In order to prevent liquid from leaking, these screws are sealed to the sheets 6 around their circumference by means of welding or adhesive 29.

In FIG. 5, the low temperature resistant metal sheets 6 are attached by means of adhesive 32 to a backing strip 31 fitted on the coupling joist 10 by means of adhesive 30, and are further secured to the coupling joist 10 by means of wood screws 33. The heads of these screws are covered with low temperature resistant adhesive 34 and in this case, the adhesive is also inserted between adjacent edges of both sheets. Consequently, a joint construction is achieved which prevents liquid from leaking.

FIG. 6 shows synthetic resin plates 7 employed for the barrier members 8. Numeral 35 identifies a'synthetic resin patching material attached onto the coupling joist 10 with adhesive 36. The synthetic resin plates 7 are fixed at the joint 9 thereof onto the above mentioned patching material 35 by means of adhesive 37 and are further fitted by means of adhesive 39 with a synthetic resin coating material 38 so as to cover this joint 9.

As will be understood from the foregoing description of FIGS. 3 to 6, the barrier member joint 9 can be fixed onto the coupling joist 10 by means suitable for the properties and nature of the barrier member 8.

Since each barrier member 8 only rests on the supporting surface 15 of one of the pressure pads 14 so as to permit relative thermal expanding or contracting movements, and particularly when the low temperature resistant metal sheet 6 is employed for the barrier members 8, the sheets 6 at the side or top walls of the tank are apt to be distorted by swelling or saggingas a result of the sheet metal being very thin. In this case, as illustrated in FIGS. 7 and 8, the barrier member 8 can be secured to the pad 14 only in a single spot at the center of the supporting surface of the pad 14, with, for example, a wood screw. A seal 41 is provided between the barrier member 8 and the circumference of the screw head by means of welding or adhesive. This arrangement can apply also to the construction in which the barrier member is made of the thin synthetic resin plate 7. FIG. 9 shows the only spot in which the synthetic resin plate 7 is secured to the pad 14 by means of a wood screw. A synthetic resin film 44, attached to the screw head 42 and to the synthetic resin plate 7 by means of adhesive 43, provides a seal.

When the barrier member 8 is secured to the pad 14 only in a single spot at the center of the supporting surface of the pad 14, distortion of the barrier member as a result of the swelling or sagging thereof can be checked even though the barrier member is thin, and relative expanding and contracting movements will not be transmitted between the pad plate 16 and the barrier member 8, since such movements are centered on the above-mentioned spot at which the barrier member is secured to the pad.

As is apparent from the foregoing description of the preferred embodiments, the present invention overcomes the problems of thermal stress concentration at the barrier member joints fixed to the coupling joists throughout the very great variation in temperature acting on the barrier members from the charging and discharging of the tank with liquified gas. The thermal stress operating upon the barrier member is small, and there is no possibility that the thermal stress caused by the expansion and contraction of the pads acts upon the barrier members. Moreover, the barrier members are supported by the pads, and for this reason do not distort. Consequently, the barrier members can be almost free of harmful influences, while of plane, thin, simple and economical construction.

We claim: 1. A low temperature liquified gas storage tank having a rigid outer wall, a low temperature resistant, liquid-tight inner wall spaced inwardly of the outer wall, and a heat insulating material between the outer and inner walls, wherein:

the inner wall comprises a plurality of rectangular barrier members interconnected to'form junctions between adjacent ones of said barrier members;

coupling joists are attached to said outer wall and are arranged in a rectangular checkerboard pattern with each rectangular area thereof corresponding in size to a single barrier member;

rectangular box-like pressure pads are arranged so that each pressure pad is in one of the rectangular areas defined by said coupling joists, said pressure pads being spaced from said coupling joists and being attached to the outer wall, each pressure pad consisting of a plate engageable by one of the barrier members and'capable of covering substantially an-entire one of said rectangular areas, and legs secured to the plate;

said barrier members having their junctions located on the coupling joists and attached thereto but not to the pressure pads; and

said insulating material is packed into the remaining void space between the outer and inner walls.

2. A low temperature liquified gas storage tank according to claim 1 wherein the barrier members are made of plywood having a layer of liquid tight material.

3. A low temperature liquified gas storage tank ac cording to claim 1 wherein the barrier members are made of sheet metal.

4. A low temperature liquified gas storage tank according to claim 1 wherein the barrier members are made of synthetic resin plates.

5. A low temperature liquified gas storage tank according to claim 1 wherein the plate and legs of the pressure pad are made of plywood.

6. A low temperature liquified gas storage tank according to claim 1 wherein at least some of the barrier 'members are secured to the plate of the pressure pad associated therewith in one spot located centrally of such plate.

7. A liquified gas storage tank according to claim 1 wherein each coupling joist is T-shaped in section, the T-shaped section having a leg portion which is attached to the outer wall of the tank.

8. A low temperature liquified gas storage tank according to claim 7 wherein each coupling joist is made of plywood.

Claims

1. A low temperature liquified gas storage tank having a rigid outer wall, a low temperature resistant, liquid-tight inner wall spaced inwardly of the outer wall, and a heat insulating material between the outer and inner walls, wherein: the inner wall comprises a plurality of rectangular barrier members interconnected to form junctions between adjacent ones of said barrier members; coupling joists are attached to said outer wall and are arranged in a rectangular checkerboard pattern with each rectangular area thereof corresponding in size to a single barrier member; rectangular box-like pressure pads are arranged so that each pressure pad is in one of the rectangular areas defined by said coUpling joists, said pressure pads being spaced from said coupling joists and being attached to the outer wall, each pressure pad consisting of a plate engageable by one of the barrier members and capable of covering substantially an-entire one of said rectangular areas, and legs secured to the plate; said barrier members having their junctions located on the coupling joists and attached thereto but not to the pressure pads; and said insulating material is packed into the remaining void space between the outer and inner walls.

3. A low temperature liquified gas storage tank according to claim 1 wherein the barrier members are made of sheet metal.

6. A low temperature liquified gas storage tank according to claim 1 wherein at least some of the barrier members are secured to the plate of the pressure pad associated therewith in one spot located centrally of such plate.