US3072088A - Cold cargo transportation means - Google Patents

Description

Jan. 8, 1963 J. F. STROSCHEIN 3,07

cow CARGO TRANSPORTATION MEANS Filed May 24. 1960 2 Sheets-Sheet 1 FlG.l

FIG.2

INVEN'TOR. JOSEPH F. STRQscHEIN ATTORNEYS Jan. 8, 1963 J. F. STROSCHEIN 3,0

COLD CARGO TRANSPORTATION MEANS Filed May 24, 1960 2 Sheets$heet 2 FIG-3 INVENTOR,

ATTORNEYS United States Patent 3,072,988 CSLD CARGO TRANSPORTATION MEANS Joseph F. Stroschein, Oceanside, N.Y., assignor to Touch international Methane Limited, Nassau, Bahamas, a corporation of the Bahamas Filed May 24, 196i Ser. No. 31,403 12 Claims. (Cl. 114-34) This invention relates to the transportation of a cold liquid cargo in containers of large capacity and relates more particularly to the construction in a ship for the stabilization of a cold liquid cargo in containers which are subject to dimensional change responsive to expansions and contractions occurring naturally in the walls of the containers due to temperature change.

This invention will be described with reference to the storage and transportation of liquified natural gas by ship from a source of plentiful supply to an area where a deficiency of natural gas exists. It will be understood that the concepts of this invention will have application also to the storage and transportation of large volumes of other cold liquids such as liquified nitrogen, liquified hydrogen, liquified air and the like. Usually, transportation of natural gas from sources of plentiful supply to an area where a deficiency exists can most economically be effected by pipeline, While the gas is retained in a gaseous state, but transmission by pipeline is not available where the source of plentiful supply is separated either by water or by excessively large distances from the area where the deficiency exists.

Under such circumstances, it has been developed that transmission can be most economically effected by reducing the natural gas to a liquified state at the source of plentiful supply for transportation of the gas in a liquified state to the area where the deficiency exists, at which point the liquified gas can be reconverted to the gaseous state for use. This is because a gas is reduced in volume by a factor of about 600 when converted from the gaseous state to a liquified state, so that 600 times as much gas can be carried in a given space in the transportation means.

When proper consideration is given to the large volume of the liquified gas to be transported, it will be evident that a storage vessel capable of high internal pressures would become impractical such that it becomes necessary to design such storage vessel for housing the liquified gas at atmospheric pressure or slightly higher. At atmospheric pressure liquified methane, present as the major component in liquified natural gas, boils at a temperature of minus 258 F. Other liquified gases such as nitrogen, oxygen, air and the like boil at still lower temperatures.

Thus, the storage container would be subject to temperature change of from about minus 258 F., when filled with liquified natural gas, to about 70-100 F. when installed at ambient temperature or otherwise freed of such liquid cargo, as during the return voyage from the area where a deficiency exists. Such temperature change will result in considerable change in the dimension of the container depending somewhat upon the materials of which the containers are formed and the dimensions thereof. From the dimensional standpoint, consideration is given to the use of containers having thousands of barrels of capacity which, in a tank of rectangular shape, may range from 50 to 100 feet in height, and from 60 to 300 or more feet in length and Width. Materials of which such containers can be constructed should be capable of high structural strength, and be characterized by the ability to resist embritt-lement when exposed to the low temperature of the liquid cargo. Most steels become embrittled at such low temperatures, but high nickel steels, stainless steels, copper, aluminum, and alloys of aluminum are capable of retaining their strengths at much lower tem- 3,072,083 Patented Jan. 8, 1963 peratures, and therefore can be used for the construction of such containers. These metals have a relatively high co-efiicient of expansion and contraction such that the dimensions of the containers may change by as much as from 6 to 15 inches, depending somewhat upon the size.

It will be apparent that a container which is subject to such dimensional change in use cannot be rigidly joined to the ships structure, otherwise such stresses could be developed as might lead either to the destruction of the ship or to the destruction of the tank, either of which would lead to most undesirable results.

Thus, it is desirable to embody the container or containers within the ships structure while permitting freedom of movement of the tank in expansion and contraction. While it is desirable to maintain the container as a free body within the ship, it is necessary also to stabilize the position of the container within the ship, otherwise the container will be subject to uncontrolled movements during the rolling and pitching of the ship and during movements of the tank relative to the ships structure, responsive to expansions or contractions. Such uncontrolled movements could lead to the development of such forces and impacts as would result in possible destruction of either the container or the ship.

Thus, it is an object of this invention to produce a ships structure embodying one or more storage containers of large capacity with means for stabilizing the position of the container or containers in the ship while permitting relative movements between the ships structure and the containers due to expansions and contractions in response to temperature change.

More specifically, it is an object of this invention to produce a means for stabilization of a cargo tank of large capacity within the hold space of a ship whereby the tank is held against relative movements responsive to the normal movement of the ship while still permitting relative movements due to changes in dimension of the tank without introducing excessive stresses either in the ships struc ture or in the tank.

These and other objects and advantages of this invention will hereinafter appear and for purposes of illustration, but not of limitation, an embodiment of the invention is shown in the accompanying drawings, in which FIG. 1 is a schematic sectional elevational view through a cross-section of a ship with a liquid storage tank mounted therein;

FIG. 2 is a sectional view of FIG. 1;

FIG. 3 is a sectional view taken substantially along the line 3-3 of FIG. 2;

FIG. 4 is a sectional View taken substantially along the line 4-4 of FIG. 2;

FIG. 5 is an enlarged sectional view showing the thermal insulating means to prevent transfer of cold from the rods to the ships structure; and

FIG. 6 is a schematic illustration of a modification for pivotal attachment of the rods.

In the copending application Serial Number 634,571 filed January 16, 1957, now Patent No. 2,954,003 and entitled Means for Transportation of Low Temperature Liquids, reference is made to similar problems in the trans portation of a cold liquid but wherein the provision is made for a difierent solution. In the aforementioned copending application, the tank is stabilized by keys and keyways in the bottom wall of the tank and the floor upon which it rests, with the keys and keyways radiating from the center of the tank whereby the tank will expand and contract crosswise relative to its support by reference to the center of the tank which becomes the stabilized position of the tank.

The upper portion of the tank is stabilized by means of cables, each of which is fixed at one end to the top wall of the tank while the other end is fixed to a spaced portion of the ships structure located above the tank. Since the cables extend angularly downwardly from the ships structure to the top of the tank, a problem arises with respect to the strain placed upon the cables upon lowering of the top of the tank due to decrease of the height of the tank when the tank is filled with cold liquid. Under such circumstances, the distance between the points of attachment naturally increases to place excessive strains upon the cables and upon the structures to which they are connected. The solution advanced in the cable means was to secure the cables to the top wall of the tank at a point beyond the center of the tank. Thus, the increase in distance due to decrease in the height of the tank is offset by a decrease indistance due to the contraction of the tank towards the center so that the result would be practically the same.

The concepts of this invention are addressed to another, simpler and more effective means for accomplishing the desired stabilization of such cargo tanks within the hold space of a ship.

In the drawings, illustration is made of a ship 10 formed with an outer hull l2 and a spaced inner hull 14. The inner surface of the inner hull is lined with a relatively thick layer 16 of a thermal insulating material to minimize heat loss into the hold space 18 of the ship and to protect the ships steel from the cold of the liquid. The tank 20 which is mounted within the hold space is preferably formed to rectangular shape for maximizing utilization of the available storage space in the hold and such tank is formed with a relatively flat bottom wall 22 and top wall 24 and sidewalls 26 joined one to the other in sealing relationship. The tank 20 can be of other shapes such as of a cylindrical section or the like, but it is generally preferred to have the bottom wall formed flat for fuller engagement with the floor 28 upon which it rests. In the illustrated modification, the tank is formed with a central dome 31% which extends upwardly from the top wall of the tank and through which the various elements for the introduction and removal of liquid cargo, for the release of vapors, and for control of the conditions Within the tank, are housed.

In accordance with the practice of this invention the tank 20 is stabilized within the hold space 18 of the ship 10 by means of a plurality of substantially horizontally disposed elongate metal tie rods 32 interconnectiong the top wall 24 of the tank with an aligned structure of the ship. For this purpose, the top wall 24 is provided with vertically disposed metal bracket plates 34 extending lengthwise of the ship and preferably, but not necessarily, in lengthwise alignment with the center portion of the tank. In the illustrated modification, use is made of a pair of laterally spaced- apart bracket plates 34a and 34b, with one pair located on one side of the tank trunk and another pair 340 and 34d on the other side of the tank trunk. It will be understood that use can be made of but a single bracket plate and that one or more such plates or pairs of plates can be employed on the top wall of the tank.

The ships structure is formed with metal girders 36, or with other portions of the structure rigid with the ship, extending downwardly from the deck of the ship to a level below the upper edge of the bracket plates and in substantially parallel relationship therewith. The girders and the bracket plates are interconnected by the metal tie rods 32 which extend through aligned openings in the upper end portions of the bracket plates and the lower end portions of the girders. As used herein, the term tie rod is meant to include elongate rods, bars, plates, or tubular members. Use can also be made of cables secured at their ends between the aligned portion of the ships structure and plates.

The ends of the tie rods extending through said openings are threaded, as at 38, for receiving nut members which are turned onto the threaded end portions 38 extending beyond said openings to develop the tension desired between the interconnected bracket plates and the girders to stabilize the tank against rolling movements of the ship. One group of tie rods extends from the center portion of the tank to a girder to one side thereof, while another group of tie rods extends from the adjacent bracket plate to a girder on the other side thereof to stabilize the position of the tank relative to the center. It will be apparent from the foregoing that the tie rods 32 which interconnect the top wall of the tank with the girders of the ships structure are not rigidly joined to the respective elements, but are operatively connected thereto in a manner which will permit a small amount of relative movement between the ends, due to stretching. Instead, the tie rods can be pivoted at their ends, as at 33, onto the aligned portions of the ships structure and bracket plates.

A similar arrangement is provided for stabilizing the tank against relative movement lengthwise of the ship due to the pitching action of the ship. For this purpose, a bracket plate 42 is fixed to the topwall of the tank to extend vertically in crosswise alignment with about the center of the tank. In the illustrated embodiment, use is made of two more bracket plates, 42a and 42b, aligned with about the center of the tank and spaced outwardly of the area occupied by the tie rods 32 to stabilize the ship against rolling forces. The ships structure is formed with transverse girders 44 extending downwardly from the deck to a level below the upper edge of the plates 42. The girders and plates are provided with aligned openings through which tie rods 46 extend for attachment by nut members 48 turned upon the threaded ends 50 extending through the openings, as previously described. As before,

use can instead be made of pivotal attachments at the ends.

In the described construction, it is desirable to protect the ships structure from the cold of the liquid and, for this purpose, it is expedient to insulate the tie rods from the ships structure. This can be achieved, as illustrated in FIG. 5, wherein a spacer 35 of insulation material is inserted as a temperature barrier between the fastening means and the plate, and the portion extending through the opening in the plate is separated by an insulating sleeve or bushing 37 so that the tie rod will operate at about ambient temperatures. The apertured plate 39 provides a seat for the fastening nuts in a Washer-like manner.

The assembly for the pitching forces illustrates an alternative construction wherein use is made of but a single plate instead of the pair of plates used in the illustrated assembly for the nullification of the rolling forces. In the use of a single plate, the openings are staggered for alignment with openings in the transverse girders to one side of the plate, and for alignment with the openings in the transverse girders on the opposite side of the plate, such that adjacent tie rods extend in opposite directions from the plate to the opposite girders.

Since the rolling forces are considerably greater than the pitching forces generated during the navigation of a ship over water, it is preferred to make use of a cluster of tie rods 32 wherein the tie rods are present in considerably larger number by comparison with tie rods 46; however, more or less can be used.

Since the tie rods extend in a horizontal direction from the girders to the connection with the top wall of the tank, reductions in the height of the tank, due to contraction, will result in movement of the attachment point along the tangent of a circle having the opposite end of the tie rod as its center so that displacement of the point of attachment in the direction of the length of the rod will remain substantially negligible, thereby to minimize development of stresses between the interconnecting elements. In the preferred practice of this invention, it is desirable originally to join the elements with the tie rods extending at a slightly upward tilt from the point of attachment to the girders to the point of attachment to the bracketplates rigid with the top wall of the tank to minimize relative displacement of the point of attachment in the direction of the length of the rod. This practice would call for the point of original attachment to be spaced from the horizontal by an amount calculated to correspond to about one-half of the amount of contraction calculated to take place in the tank so that the point of attachment will pass through equal angles from the horizontal tangent.

While the key and keyway construction described in the aforementioned copending application can be employed between the bottom wall of the tank and the door upon which its rests, the forced relationship existing between the flat bottom wall of the tank and the floor, coupled with the described means for stabilization at the top of the tank, is sufiicient to maintain the tank in the desired position within the insulated hold space of the ship without the use of bottom keys and keways. The weight of the tank, the area between the flat bottom wall and the floor, and the means for stabilizing the position of the tank at the top, are sufiicient to prevent relative movements of the tank from the stabilized position, notwithstanding the rolling and pitching movements of the ship while still permitting relative movement between the tank and the ships structure within the stabilized position due to expansions and contractions on account of temperature change. The floor should be constructed of a material of low thermal conductivity and it should be characterized by good structural strength and dimensional stability for support of the tank or tanks even when filled with liquid without breakdown of the insulation under load and without loss of its thermal insulating characteristics. For this purpose, the floor can be constructed of a thick layer of a highly porous wood such as balsawood. It is preferred to face the upper surface of the floor with a layer of hardwood, preferably in the form of a laminate, capable of taking the forced conditions to which the fioor will be exposed during installation and use, and which is also capable of neutralizing the forced conditions existing when use is made of interfitting keys and keyways between the bottom of the tank and the floor forthe purpose of additional stabilization of the tank at its bottom side.

It will be understood that the concepts described will be applicable to a ships structure in which one or more tanks are arranged in side-by-side and/or in end-to-end relation, but wherein the tanks are arranged in a single layer. When, as in the illustrated modification, the tanks are adapted to carry a cold liquid cargo, a layer of insulation 52 such as fiberglass batts, corkboard, balsawood, foamed plastics, bags of pearlite and the like may be disposed over the top wall of the tank, preferably but not necessarily, substantially to fill the space between the top wall of the tank and the girders on the bottom side of the ships deck.

For purposes of simplification, the attachments to the tanks are omitted, but it will be understood that each tank will be fitted with a filling tube and with a delivery tube for the liquid cargo, vapor relief passages, inerting passages and the like control equipment.

It will be understood that the ships girders to which the tie rods are connected may be replaced by other elements rigid with and forming a part of the ships structure for use as a part of the stabilization means for the tanks. It will be further understood that various changes may be made in the details of construction, arrangement and operation without departing from the spirit of the invention, especially as defined in the following claims.

I claim:

1. In a ship having an insulated hold space and one or more metal tanks of large capacity for housing a liquid cargo having a temperature ditfering widely from ambient temperature whereby the metal tank will be subject to changes in dimension in response to expansions and contractions due to temperature change, the improvement which comprises a means for stabilizing the position of the tank within the insulated hold space to resist displacement in response to the pitching and rolling of the ship while permitting freedom of movement of the tank relative to the ships structure in response to changes in dimensions of the tank due to expansions and contractions from temperature change comprising a bracket rigid with the top wall of the tank and having a portion extending vertically therefrom, a structural member of the ship rigid with the ship and extending in spaced parallel relation with the vertical portion of the bracket and dimensioned horizontally to overlap at least a portion of said vertically disposed member, aligned openings in said vertically disposed member of the bracket and said structural member of the ship, elongate rigid tie rods extending continuously through said aligned openings at a slight upward inclination from said structural member of the ship to said vertically disposed member of the bracket when at ambient temperature, and means on the portions of the rods extending through said aligned openings for tensioning the rods between said structural and bracket members.

2. A ship as claimed in claim 1 in which the vertically extending portion of the bracket and the said structural element of the ship are aligned lengthwise of the ship.

3. A ship as claimed in claim 1 in which the vertically extending portion of the bracket is aligned with the central portion of the tank and extends lengthwise of the ship.

4. A ship as claimed in claim 1 in which more than one bracket with a vertically extending portion is aligned lengthwise of the ship with substantially the central portion of the tank and in longitudinally spaced apart relation.

5. A ship as claimed in claim 1 in which a pair of laterally spaced apart vertically extending portions are provided in the top wall of the tank in lengthwise alignment with the ship and in substantial alignment with the central portion of the tank with said rods extending in one direction from one of said vertically extending portions and with other rods extending in the opposite direction from the other of said vertically extending portions and laterally spaced apart structural members rigid with the ship engaged by said oppositely extending rods.

6. A ship as claimed in claim 1 in which the means on the through extending portions of the rods :for tensioning the rods between the bracket and the structural member of the ship comprises threaded end portions on the rods and nut members turned down upon the through extending end portions.

7. A ship as claimed in claim 1 in which the structural member of the ship to which the rods are connected comprises girders extending downwardly from the bottom side of the ships deck to a level below the upper edge of the vertically extending portion of the bracket.

8. A ship as claimed in claim 1 in which the vertically extending portion of the bracket is aligned crosswise of the ship in substantial crosswise alignment with the central portion of the tank.

9. A ship as claimed in claim 8 in which the structural member of the ship comprises a pair of structural members in longitudinally spaced apart relation on opposite sides of the bracket and in which the rods extend from the bracket in one direction to one of said structural members and from the bracket in the opposite direction to the other of said structural members.

10. A ship as claimed in claim 1 in which a plurality of brackets are provided on the tank with some of the brackets having portions extending vertically in lengthwise alignment of the ship and others of the brackets having portions extending vertically in crosswise alignment of the ship and in which the ship is provided with a plurality of structural members extending in parallel relationship with said vertically extending portions of the brackets and on opposite sides thereof and tie rods extending between each vertical portion and its corresponding structural member.

11. A ship as claimed in claim 10 in which the number of rods extending crosswise of the ship between length wise aligned brackets and structural members is greater than the number of rods extending lengthwise of the ship between crosswise aligned members.

12. In a ship having an insulated hold space and one or more metal tanks of large capacity for housing a cargo liquid having a temperature differing widely from ambient temperature whereby the metal tank will be subject to changes in dimension in response to expansions and contractions due to temperature change, the improvement which comprises a means for stabilizing the position of the tank within the insulated hold space to resist displacement in response to the pitching and rolling of the ship while permitting freedom of movement of the tank relative to the ships structure in response to changes in dimensions of the tank due to expansions and contractions from temperature change comprising a plurality of substantially rigid tie rods disposed above the top of the tank References Cited in the file of this patent UNITED STATES PATENTS 2,863,297 Johnston Dec. 9, 1958 2,864,527 Altman et al Dec. 16, 1958 2,896,416 Henry July 28, 1958 2,905,352 Henry Sept. 22, 1959 2,926,810 Yeager Mar. 1, 1960 2,954,003 Farrell et a1 Sept. 27, 1960

Claims (1)

12. IN A SHIP HAVING AN INSULATED HOLD SPACE AND ONE OR MORE METAL TANKS OF LARGE CAPACITY FOR HOUSING A CARGO LIQUID HAVING A TEMPERATURE DIFFERING WIDELY FROM AMBIENT TEMPERATURE WHEREBY THE METAL TANK WILL BE SUBJECT TO CHANGES IN DIMENSION IN RESPONSE TO EXPANSIONS AND CONTRACTIONS DUE TO TEMPERATURE CHANGE, THE IMPROVEMENT WHICH COMPRISES A MEANS FOR STABILIZING THE POSITION OF THE TANK WITHIN THE INSULATED HOLD SPACE TO RESIST DISPLACEMENT IN RESPONSE TO THE PITCHING AND ROLLING OF THE SHIP WHILE PERMITTING FREEDOM OF MOVEMENT OF THE TANK RELATIVE TO THE SHIP''S STRUCTURE IN RESPONSE TO CHANGES IN DIMENSIONS OF THE TANK DUE TO EXPANSIONS AND CONTRACTIONS FROM TEMPERATURE CHANGE COMPRISING A PLURALITY OF SUBSTANTIALLY RIGID TIE RODS DISPOSED ABOVE THE TOP OF THE TANK AND FIXED UNDER TENSION AT ONE END TO A MEMBER FIXED TO THE TOP OF THE TANK AND AT THE OTHER END FIXED TO THE SHIP''S STRUCTURE, SAID TIE RODS EXTENDING AT A SLIGHT UPWARD INCLINE FROM THE END FIXED TO THE SHIP''S STRUCTURE TO THE END FIXED TO THE MEMBER FIXED TO THE TOP OF THE TANK WHEN AT AMBIENT TEMPERATURE.

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