US3272373A

US3272373A - Flexible and elastic tanks for transporting liquids in bulk

Info

Publication number: US3272373A
Application number: US315329A
Authority: US
Inventors: Alleaume Jean Henri; Hamel Denis Marcel Henri
Original assignee: Individual
Current assignee: Individual
Priority date: 1962-10-10
Filing date: 1963-10-10
Publication date: 1966-09-13
Anticipated expiration: 1983-09-13
Also published as: NL299514A; FR1352835A; BE638476A; ES292373A1; NO115440B; GB1035957A

Abstract

1,035,957. Carrying liquid cargo. GAZOCEAN S.A., and PNEUMATIQUES CAOUTCHOUC MANUFACTURE ET PLASTIQUES KLEBER COLOMBES. Oct. 10, 1963 [Oct. 10, 1962], No. 40020/63. Headings B7A and B7S. [Also in Division F4] A ship's hull 30, Fig. 3 (not shown), having insulation 31, has a main tank 33 therein for containing liquid surrounded by a second tank 36, each tank being formed from a non-metallic membrane of a flexible and elastic material, e.g. nitrile rubber or polyester urethane. The space 37 between the tanks is filled with a pressurized gas, a flexible cellular material or a liquid. Alternatively, the upper part of the space may be filled with cellular material and the separated lower part by a pressurized gas. The space 37 may also be divided into several sealed chambers by membranes which extend between the tanks, each chamber being filled with gas at different pressures. Inflatable reinforcing ribs (Fig. 2, not shown) filled with an inert gas may be arranged on the internal surface of the main and/or the second tank.

Description

J. H. ALLEAUME l-:TAL 3,272,373

FLEXIBLE AND ELASTIC TANKS FOR TRANSPORTING LIQUIDS IN BULK Filed Oct. lO,

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INVENTORS JEAN H. ALLEUME ENIS HAMEL ATTORNEY sept. 13, 196s United States Patent O 3,272,373 FLEXIBLE AND ELASTIC TANKS FOR TRANS- PORTING LIQUDS 1N BULK Jean Henri Alleaume, 121 Ave. du Marechal Foch, Saint- Cloud, Seine, France, and Denis Marcel Henri Hamel,

4 Ave. Victor Hugo, Saint-Mande, Seine, France Filed Oct. 10, 1963, Ser. No. 315,329 Claims priority, application France, Oct. 10, 1962, 911,881 12 Claims. (Cl. 220-9) The present invention relates to flexible tank means adapted to rest on the hull of a `ship for transporting liquid. This arrangement is particularly suitable for transporting cold liquefied gases at a pressure close to atmospheric pressure by sea or river.

As is known, in ships of this kind, the walls of the tank do not under go hydrostatic and hydrodynamic stresses, which are fully transmitted to the hull of the ship and supported by it.

However, the walls of the tanks which may undergo considerable variations of temperature and whose dimensions and geometrical shape remain more or less constant, since they are rigidly connected to the hull of the ship which supports them, must be designed to support dimensional variations which are often considerable, without abnormal stresses.

Different solutions, whose object is to confer qualities on the walls of the tank permitting them to resist these dimensional variations, without sustaining damage, have already been suggested. Thus it has been proposed to make tanks whose walls are made up either of a welded assembly of corrugated metal plates or of flat plates connected together by means of flexible bellows elements which are also metal; in each of these cases, the metal Walls are made integral with an insulating layer. It has also been proposed to fix a film of a synthetic material to the insulating layer, this film having the required qualities of impermeability and chemical inertness.

The structures made in this way exhibit thermal expansions yor contractions which are not exactly compensated at all points. This is the case particularly when the walls are made up of a film fixed to the insulating layer, but also when they are metal plates.

Further, in certain cases-for instance, in the case of a heavy swell or a collision-they may sustain severe damage which may even render them no longer airtight since they must, by their very design, follow all the deformations of the hull of the ship and have virtually no mechanical resistance.

In the case of tanks with metal walls, the production of the usually fairly complicated shapes which are necessary has the further disadvantage of entailing an operation which is often fairly delicate and, moreover, likely to render the metal less resistant to thermal fatigue; in any case, it may be considered relatively expensive.

Moreover, the checking, and, where necessary, the repair of the tank and the insulating layer are long and expensive operations which often necessitate the removal and sometimes even the destruction of certain parts.

Finally, in all cases, the positioning of the walls of the tanks (films or metal plates) is an operation which cannot be carried out independently of the construction of the ship, Whose going into service must therefore be prolonged by the time necessary for the operation of positioning the walls of the tanks.

Tanks have also been proposed which are made up of a membrane forming a structure independent of the remainder of the ship on which it rests directly or indirectly, without however being rigidly fixed to it.

In the drawings:

FIGURE 1 shows a cross-section through a prior art ICC tank made up of a membrane forming an independent structure.

FIGURE 2 shows a perspective view of a ltank which is used as first tank;

FIGURES 3, 4, 5 respectively show cross sections through various combinations of ship hulls in accordance with the invention. Y

In the structure shown in FIGURE 1, the ships hull, schematically shown at 10, has an inner coating of a thermally insulating layer 11, the liquid to be transported being presumedas frequently occursto be at a low temperature. The liquid is contained in the tank 12 made of a membrane 13 which is kept in place, by any appropriate fixing means, schematically illustrated at 14, to the lips of the orifice 15 used for filling and emptying the tank. Thus the tank is formed by a sort of bag held at the neck and taking up, when full, all the available space enclosed by the insulating layer. The membrane 13 is then applied to the insulating layer 11 which transmits the hydrostatic and hydrodynamic stresses to the hull. The membrane 13 must have the usual qualities of irnpermeability and chemical inertness relating to the product to be transported. It must also be sufficiently flexible at its working temperature to be able to alter its shape so that the parts in contact with the liquid transported remain constantly applied to the layer 11 to whatever extent the tank is filled and whatever the movement of the ship may be. It must also have sufficient elasticity to sustain without damage the thermal stresses it undergoes.

It has only been proposed to make such tanks of a composite material, for example a glass fiber cloth which is coated with a plastic chemically inert to liquid. These tanks have only a Wall.

The heterogeneity of the material makes difficult the construction of such tanks by welding and the elasticity and the flexibility of coated glass fiber cloth are insufficient to transmit -completely hydrodynamic and hydrostatic stresses and to sustain the thermal stresses.

It is also necessary, as an additional security measure, to duplicate such a tank by a second so-called secondary barrier tank, so that there exists at every point at least two fluid tight walls between the liquified gas `and the rigid structure of the ship. This secondary barrier is made up of metallic sheets placed inside the thermally insulating layer.

In the present invention, these Adifliculties are successfully avoided.

Our tank is made up of a homogeneous, flexible and elastic material and has two Walls so that there exists at every point at least two fluid-tight walls between the liquified gas and the rigid structure of the ship.

The first tank which contains the liquid is duplicated by the second tank made of the same material or of an analogous homogeneous material.

The second tank is in contact with the first tank or it is separated from the first tank. The second tank can bebound to the first tank by different means or it can be independent of .the first tank.

Several elastomers may be used, e.g. nitrile rubbers, polyurethanes, and similar elastomers. A polyester urethane such Ias that sold under the trademark Estane has been found particularly suitable because of its impermeability, its resistance to hydrocarbons, its flexibility, its elasticity, its mechanical resistance and its resistance to wear, all of these being qualities Which it keeps at low temperatures. Tanks according to the present invention may be made of sheets of a suitable elastomer, such as that known under the trademark Estane,5 such sheets being relatively thin, e.g. 1 to 4 mm. joined together by high frequency lwelding, by hot-air welding or by any other appropriate means.

It will be appreciated that the invention is not limited to tanks whose walls are made of a specific elastomer. Any homogeneous material having the required qualities of impermeability and chemical inertness which maintans, at the temperature at which the liquid is transported, sufficient exibility and elasticity, is suitable.

The tanks according to the invention can be subjected to thermal fatigue due to the considerable variations in temperature they undergo, with no risk of them tearing, as a result of homogeneity and the elasticity of their wall at the working temperature. They transmit the hydrostatic and hydrodynamic forces to the hull better than previously known tanks. The security is increased as a result of the two walls between the liquid and the structure of the ship.

IFurthermore -it is unnecessary to place a distinct secondary -barrier which entails considerable shortening of the construct-ion period of the ship. lFor periodic checks, and where necessary, repairs, these tanks lmay easily lbe fully or partially withdrawn from the cell in which they are placed.

Finally, tanks according to the invention facilitates the successive or simultaneous transport of chemically or physically incompatible cargoes-the products to be transported may easily be placed in separate or different tanks.

In an embodiment which is not illustrated, the first tank and the second tank are independent and are directly in contact. The top o-f the first tank is applied on the top of the hold by a plurality of straps and the superior part of the second tank (Which is the secondary barrier) is fastened to the walls of the hold.

FIGURE 2 shows a particular embodiment of a first tank. '1`o prevent abnormal strain on the neck of the tank, inflatable ribs 21 are arranged on the inner wall thereof. Their object is to maintain the shape of the tank 'when the Ilatter is empty or only partially filled. To elim- Iinate `any risk of explosion in the case of leakages, they are inflated with an inert gas such as nitrogen.

In the embodiment illustrated in FIGURE 3, the hull 30 and also' the lower surface of the deck are covered by a thermally insulating layer 31.

The walls of the tank 32 are made up of a membrane 33, which, as in the preceding example, forms a sort of bag held by its neck with an appropriate fixture schematically illustrated at 34, to the lips of the filling and emptying orifice 35.

A secondary tank whose walls 36 are applied directly to the layer 31 completely surrounds the tank 32. It is designed and made like the tank 32 from which it is separated by a layer 37 of an inert gas kept at a pressure approximately equal to the pressure at the bottom of the tank 32, at least during the period the tank 32 contains liquid. It will be appreciated that the walls 36 and 33 are hermetically connected together at the top, and there are means, which are not shown in the figure, and which do not per se form part of the invention, which make it possible to insert the compressed gas in the gap between the walls 36 and 33.

The pressure of the gas of the layer 37 applies the walls 36 of the secondary tank against the thermally insulating layer 31 and keeps the main tank 32 separated from the secondary tank. The gaseous layer 37 isthermally insulating, which makes it possible to reduce considerably the thickness of the layer 31.

The walls 36 of the secondary tank form a safety secondary barrier, which, should there be a break in the seal of the main tank 32, insulates the rigid struct-ure 30 from the cold liquid. As a result of its flexibility and its elasticity, the wall 36 could sustain without damage the stresses it would undergo if the cold liquid trans-ported in the bank 32 came into contact with it by accident.

This arrangement also makes it possible to protect the Walls 33 and 36 from any stress resulting from a change of shape of the hull and to obviate any friction between them and the layer 31.

According to one modification, the layer 37 is made up of a'liquid having appropriate chemical and physical characteristics. The layer 37 may also be made of a fiexible cellular material.

According to another modification of the invention, the gap between the wall 36 and the wall 33 is maintained at several points by means of membranes connecting the wall 33 and the Wall 36 around their Whole perimeter. Thus a certain number of sealed chambers are defined, each of which may be supplied With a pressure different from that of the other chambers and which is to be adapted to the pressure of that part of the Wall 33 which corresponds to the particular chamber.

A particular embodiment of this modification is shown in FIGURE 4.

The

Walls

43 and 46 are analogous to the walls 33 and 36 in the embodiment shown in FIGURE 3. A membrane 48 is fixed to each of them in the neighborhood of their lower edges and, running around the entire perimeter, dedines two sealed chambers 47a and 'll-7b. :Each of these chambers is supplied with a different pressure. The pressure of the chamber 47 b may be at least equal to the pressure exerted on the bottom of `the tank containing the liquid and the pressure of the -chamber 47a may be the pressure necessary for keeping the tank formed by the wall 43 in place. In this particular case, the carrying function of the tank (carried out by the chamber 47h) is dissociated from the centering function (carried out by the Achamber 47a).

In the embodiment shown in FIGURE 5, the main and secondary tanks are arranged as in the embodiments illustrated in FIGURES 3 and 4. The

references

53 and 56 designated the walls lof these tanks. They are analogous to the

walls

33 and 36, 43 and 46 in the preceding examples.

The gap between these walls is filled at its upper part 57s with a flexible cellular matrial, and may, if required, be hermetically sealed, and at its lower part 57i by an inert gas which is kept under pressure. Should the seal of the cellular material which fills the gap 57s be insufficient, iit is possible, for example, to separate the two

parts

57s and 57i from one lanother by a membrane 59 fixed around the entire perimeter onto the Wall 53 and the wall 56.

As in the preceding example, it is also possible to separate the gap 57i by means of a membrane fixed to the wall 53 and the wall 56 along their edges and thus to define two chambers which may be supplied with different pressures.

Where the principal tank is surrounded by a secondary tank, it is possible to arrange ribs inflated with an inert gas on the internal surface of each or merely on the internal surface of one of them.

It will be appreciated that the invention is not limited to the foregoing embodiments, and that modifications may be made to the specific details set forth.

What is claimed is:

1. A device for the transport of liquids in bulk comprising an outer wall, a thermally insulating layer disposed adjacent the inner surface of said outer wall and a double- Walled container disposed within said thermally insulating layer, said double-walled container consisting of spaced main and second tanks, each of said tanks bei-ng made of a homogeneous and intrinsically flexible and elastic material.

2. Device for the transport of liquids as claimed in claim 1 wherein said tanks consist of a non-reinforced membrane made of the same homogeneous and intrinsically flexible and elastic material.

3. Device for the transport of liquids as claimed in claim 1 wherein at least one of said tanks consists of a non-reinforced membrane made of a polyester urethane.

4. Device for the transport of liquids as claimed in claim 1 wherein the space between said main tank and said second tank is filled with a gas which is kept under pressure.

5. Device for the transport of liquids as claimed in claim 1 wherein the space between `said main -tank and said second tank is filled with `a flexible cellular material.

6. Device for the transport -of liquids as claimed in claim 1 wherein the space between said main tank and said second tank is lled with a liquid.

7. Device for the transport of liquids as claimed in claim 1 wherein the space between said main tank and said second tank is yfilled at its upper part with a ex-ible cellular material and at its lower part with a gas which is kept under pressure.

8. Device for the transport of liquids as claimed in claim 1 wherein said main tank and said second tank are connected with one another by at least one membrane dividing up the space separating said tanks into sealed chambers.

9. Device for the transport of liquids as claimed in claim 1 wherein said thermally insulating layer envelops all sides of said second tank.

10. Device for the transport of liquids as claimed in claim 8 wherein each sealed chamber is filled with a gas kept under pressure at a pressure which is different for each chamber.

11. Device for the transport of liquids as claimed in claim 8 wherein at least one of said sealed chambers is lled with a flexible cellular material and at least one of References Cited by the Examiner UNITED STATES PATENTS 611,207 9/ 1898 Morrill 15G-2.1 2,387,258 10/ 1945 Hague. 2,477,787 8/ 1949 Cook 229-14 2,484,608 10/1949 Cheyney 229-14 2,751,953 6/1956 Grimm. 2,991,906 7/ 1961 Eligoulachvili 114-74 2,994,452 8/1961 Morrison 220-9 3,058,624 10/ 1962 Westlake 222-107 3,067,712 12/ 1962 Doerpinghaus 114-74 3,164,186 1/1965 Weber et al. 150-3 JOSEPH R. LECLAIR, Primary Examiner.

FRANKLIN T. GARRETT, Examiner.

J. F. MCNULTY, Assistant Examiner.

Claims

1. A DEVICE FOR THE TRANSPORT OF LIQUIDS IN BULK COMPRISING AN OUTER WALL, A THERMALLY INSULATING LAYER DISPOSED ADJACENT THE INNER SURFACE OF SAID OUTER WALL AND A DOUBLEWALLED CONTAINER DISPOSED WITHIN AND THERMALLY INSULATING LAYER, SAID DOUBLE-WALLED CONTAINER CONSISTING OF SPACED MAIN AND SECOND TANKS, EACH OF SAID TANKS BEING MADE OF