US3064612A

US3064612A - Carrier constructions for bulk fluids

Info

Publication number: US3064612A
Application number: US63782A
Authority: US
Inventors: Kenneth E Gardner; Albert P Veltre; Walter R Gerich
Original assignee: MARYLAND SHIPBUILDING AND DRYDOCK Co
Current assignee: MARYLAND SHIPBUILDING AND DRYDOCK Co
Priority date: 1960-10-20
Filing date: 1960-10-20
Publication date: 1962-11-20
Anticipated expiration: 1979-11-20

Description

1962 K. E. GARDNER ETAL 3,064,612

CARRIER CONSTRUCTIONS FOR BULK FLUIDS Filed Oct. 20, 1960 4 Sheets-Sheet l Nov. 20, 1962 K. E. GARDNER ETAL 3,064,612

CARRIER CONSTRUCTIONS FOR BULK FLUIDS Filed Oct. 20. 1960 4 Sheets-Sheet 2 INVEN TOR. KA'A/A/ETH E. MED/YER 144 175? 1? GER/CM ALE EFT P VELTRE' Nov. 20, 1962 K. E. GARDNER ETAL 3,064,612

CARRIER CONSTRUCTIONS FOR BULK FLUIDS 4 Sheets-Sheet 3 Filed Oct. 20. 1960 BY Azsikr 2 1 5025 Nov. 20; 1962 K. E. GARDNER ETAL CARRIER CONSTRUCTIONS FOR BULK FLUIDS 4 Sheets-Sheet 4 BY AME/5P7 .P 14-27795 Filed Oct. 20. 1960 The present invention relates to vehicular carrier constructions for bulk fluids and it comprises a continuationin-part application based upon patent application Serial No. 829,410, filed July 24, 1959, and now abandoned. More especially, the invention relates to carrier vessels such as-are used to transport hydro-carbon fuels and the likein liquid form. Although the invention is defined with specific reference to transporting hydrocarbon fuels, it has like application to transporting other liquids which must ofnecessity be carried at: temperatures varying appreciablyabove and below the ambient of the carrier structure;

Problems arising from the transportation of hydrocarbon fuels include loss by evaporation. In normal transporaunless the gases of vaporization are withdrawn and liquefied -by refrigeratioma notable loSs of cargo occurs. This construction will permit safe circulation-to these ends.

Safety of thevesselstructure, in the event of leakage and temperature drop, presents a situation that must also bemet. Accordingly, all specifications mustmeet the recognized standards of the Classification Societies such as the American Bureau of Shipping. This invention has therefore been devised with provisions for liquefying the gases of vaporization by refrigeration and returning the hydrocarbons in liquid form to the cargo tanks which are located within the hold of the carrier. Particular attention is given to the provision of a secondary barrier to contain the cargo upon leakage and in such massive constructions as ships, this, too presents practical and economic problems which have been solved herein. Moreover, an effort is made hereby to utilize maximum hold space in confining the respective cargo tanks without sacrifice of safety to the ship while at the same time creating a lightweight and highly safe means for retaining the tanks, considering the motions imposed by variant seaway, weather conditions or cargo shifting.

It is an object of this invention to provide means for safely securing a number of large fluid retaining cargo tanks within the holds of a carrier, whereby gaseous vapors of said tanks may be continuously liquefied by refrigeration and the liquid returned to the cargo tanks.

In the area of safety control, it is important that any leakage in the cargo tanks be adequately detected, confined and corrected without resort to the expense of removal of the tank. Therefore, a space is provided between the boundary of the cargo tanks and the ships structure to permit ready inspection and subsequent repair to any of the tanks. Detection and repair in transit is thus an objective of the invention, as is control against excessive temperature drop to structural elements of the carrier.

Yet another object of invention is to provide in carriers of the type defined, cargo tank anchoring means whereby independent cargo tanks are permitted multi-directional expansion and contraction in horizontal and vertical planes, all without rigid tank attachment to deck structure, the anchoring means being immovable with respect to the carrier structure but yielding to movement of cargo tanktructure.

Still another objective of invention lies in providing unique means for safely securing cargo tanks to vessel construction permitting expansion and contraction in re sponseto variation in the temperature above and below the ambient of the vessel.

Another object of' the invention is to provide unique weatherudeck accessto each fiuid cargo tank, by flexible connection to the ships structure, allowing free movement of respective cargo tanks independent of any movement ofthe ships hull.

With these and other objects in view, the invention and all modifications thereof will be more completely understood from reference to the following drawings in which:

FIGURE 1 is an elevational or profile view of a typical carrier vessel enlarged to accommodate a grouping of independent cargo tanks in longitudinal alignment;

FIGURE 2 is a View in vertical or midship section of the'carrier and hold of FIGURE 1;

FIGURE 3 is aschematic of the foundation assembly for one complete cargo:tank containing at least two cargo cells;

FIGURE 4 is a fragmentary view in expanded perspective of a detail of the centerline foundation assembly shownschematically in FIGURE 3;

FIGURE 5 is a fragmentary view in expanded perspective'showing the detail bolting for inboard support depicted schematically in FIGURE 4;

FIGURE 6 is an expanded view in fragment of a per tion of tank stabilizing assembly appearing atop the tank of FIGURES 2 and 3;

FZGURE7 is an expanded view in fragment of an outboard foundation member appearing in support of the tankof- FIGURES 2 and 3;

FIGURE 8 is a fragmentary view in expanded perspective showing the detail bolting for an outboard support depicted schematically in FlGURES 2 and 3.

With specific reference to FIGURE 1, there is shown a shiplilo having a displacement hull 1%, bridge H 4 and afterquarters or poophouse 1%. The ship has masts 1G8 and booms 168'. The particular construction shown is of a liquid hydrocarbon fuel (LPG) carrier wherein the relati ve disposition of cargo tanks to hull appears in fragment. The deck lfrii, as secured to the hull construction'1ii2, includes in its external configuration, transverse structural beams 120, said beams being more clearly depicted'with reference to FIGURE 2 at the top thereof. The beams-extend athwartships to the outer hull, those substantially aligned with the false bulkhead being in supporting alignment with the upper trailing extension thereof;

Theoverall hull ltiZincludes an inner or second barrier hull- 112. (FIG. 2), spaced from the outer hull by reinforcement shown; the included space providing wing anddouble-bottom" tanksfor a liquid cargo other than the tank-contained principal hydrocarbon. F or example, certain grades of'fuel oils may be carried in the wing tanks which would provide ballast and also serve to insulate or reducetemperature drop: in the carrier structure should leakagefromthe cargo tanks occur. Other safety factors include the fixed concrete ballast 116 on the bottom 114 of-inner hull H2 and there is provision for Water spray within the cargo holdand between inner hull and cargo tank. The water spray system is adapted to bring, vapor heat to the area in which a leakage might occur, this area including not only thecargo hold between tank and inner. hull but also topside and the refrigerating compressor'rooms;

In thisconstruction, six major cargo tanks are shown each having conventional interior framing and each: being compartmented into adjacent water tight cells and 140'. The hatches and appropriate pumping stationsv serving each-of the cells of the respective major cargo tanks 13% may be seen in FIGURE 2. Cargo tanks 3 are disposed in alignment with the keelson of the ship, in balanced relation thereto. A suitable tank sluice valve 144 is fitted at the lower extremity of bulkhead 142. Its operation is remote from the control above the weather deck 110.

The exterior of each cargo tank is insulated with consecutive thicknesses of mineral wool insulation 132 which is preferably Johns Manville BX-S or equivalent, covered by galvanized steel wire cloth #8 mesh, and alternate coats of Foster fire-retardent mastic and plastic vapor barriers as recommended by the insulation manufacturer. This insulation is to be attached to the cargo tank by means of Nelson welded studs, sealed in an approved manner. The bottom of the main deck 110, in the tank hold areas between the longitudinal and transverse bulkheads, is also insulated with 1 of AP. 320 Fiberglass. As each cargo tank hold is made of nickelsteel, this provides a second barrier to insure safe containment within the individual holds. These cargo tanks 130 are each designed to retain in capacity 95% liquid gas, at approximately 45 F., atmospheric pressure.

Water tight bulkheads 118 join the deck, second barrier, inner bottom, and separates respective cargo tanks as shown in FIGURE 1.

Individual tank foundation assembly of FIGURE 3 will now be described. It will be appreciated that each tank is provided with its individual supporting foundation assembly 150, similarly arranged as in FIGURE 3. These assemblies are rigid with ship structure permitting relative movement of the supported tank but fixing the latter at its center. The tanks 130 each have abutment members 136 hereinafter described, foundation blocks on the inner bottom and at the sides thereof, a longitudinal tank block, a corresponding transverse tank block, not shown, and longitudinal stability projection block atop the tank. These elements comprise bearing and stability members for the tank.

Support for respective tanks 130 includes, in the foundation 150, the longitudinally disposed keelson member 152 (FIGURES 3 and 4) having a channel 154 .supporting the tank bearing slides 156 between Micarta bearing blocks 158. These blocks are located coextensively with channel 154 beneath the slides and at both sides thereof in the channel. The blocks comprise a phenolic laminate made by impregnating sheets of fabric with resin and combining them under heat and pressure. The slides 156 are secured by weldment to the longitudinal center of each cargo tank as shown in FIGURES 2 and 4. These slides are preferably equal in length to keelson member 152.

The entire foundation 150 is best shown in FIGURE 3, wherein the foundation members 152 and 152'; intersect and rest upon the inner bottom 114 of the ship, foundation members and hull bottom being partially covered by the fixed ballast 116. The tank bearing surfaces of the

foundation members

152 and 152 are parallel to the dihedrally shaped tank bottom. As the center of shrinkage of tanks 130 is at the bottom center thereof, the tank bottom is rigidly secured by weldment to the intersection of 152 and 152' keelson by fastening or bolting. From the center outwardly, fore and aft, however, the tank bearing slides and keelson member are in longitudinal sliding relation as shown in FIGURES 4 and 5. The tank footings or slides 156 contain multiple elongated keyways 160 accommodating anchor bolts 162 for movement of the slides or footings relative to the corresponding foundation assemblies and tank blocks. The longitudinal and transverse supporting

member beams

152 and 152 are likewise apertured to hold the anchor bolts 1 62 relatively fixed with respect to foundation and ship structure. Washer 164 is non-conductive, permitting tight engagement of the tank in expansion and contraction relation to foundation. Apertures 160 for these 'footings are of increasing diameter from inboard to outboard, that is, from the centerline of the ship to its sides.

This arrangement permits unrestricted tank expansion and contraction longitudinally along the keel, transversely abeam and universally otherwise. All bearing surfaces of the foundation are preferably graphite lubricated. Referring to FIGURES 6 and 7 the expansion and contraction of the tank is accommodated universally by having corresponding footing and stabilizer projections apertured circularly. (See FIGURE 8.) For instance, the stabilizer has apertures of greater diameter than does the corresponding bearing block 174 and fixed guide 172. Both block and guide are fixed, having aligned apertures of diameter equivalent to that of the bolts whereas the movable stabilizer apertures permit universal and vertical movement as shown (FIGURE 6). Outboard of the keelson member the foundation assembly includes a plurality of aligned supports 153 each having corresponding bearing blocks 155 similarly apertured to anchor the bolts 162 vertically. The adjacent tank slides 157 define enlarged apertures 159 permitting universal expansioncontraction movement of the tank at its extremities relative to the fixed foundation assembly. See FIGURES 7 and 8.

To retain the tank in position, the assemblies include collision chocks forward and abeam of each tank, opposite corresponding tank abutment member 136. The

abutment members carry a maple wood chock; chocks and corresponding abutment members being appropriately spaced on three sides of each tank in staggered relation to each other. The forward chocks are mounted uptLn the bulkhead which is adjacent to the front of each tau The cargo tanks per se are designed to withstand a 5 p.s.i.g. pressure plus the gravity head of the liquefied hydrocarbon gas, where the specific gravity is approximately 0.585 at -45 F. Steel used in the tanks is preferably ASTM A-203 grade D or E firebox to meet ASTM-A300, Class 2 with longitudinal charpy test to 75, the same steel being used for the longitudinal wing bulkhead plating and suitable stiffeners thereof, as well as the transverse bulkheads inboard of longitudinal bulkheads. The inner bottom plating under the concrete ballast is of the same steel.

Deep-well pumps and hatches serve each of the cells 140 and 140' of tanks 136. Quite aside from providing personnel access to the tank interior, the hatches 200 include vapor suction liquid level, alarm float, vent and fill openings as well as a liquid return opening. The hatches 260 being located between transverse main deck girder 120 are attached to the deck by flexible water tight connection 220 made of neoprene or the like. The connection 220 is retained between top hardwood rings and a suitable hardwood projection. The entire hatch and tank is thus universally movable irrespective of the deck, there being no rigid connection between tank and the deck opening which surrounds the hatch. The access hatch does not, of course, give access to the hold, but suitable hatches are provided between each tank, adjacent to the watertight transverse bulkheads.

Deepwell pump 3% is shown in FIGURE 2, the same including similar means for flexibly retaining the assembly in watertight connection with the main deck. The pump shown includes a flexible connection 320, spaced inwardly from its circular water shield. From the drawing it will be noted that each pump per se is fixed to the top only of the tank cell, requiring no rigidity or attachement to the deck other than by seal 32!). A circular guide 322 fits about the bottom of the pump to stabilize it against excessive swinging upon pitch and roll of the ship. This pump is preferably insulated up to its motor mount above the plane of the main deck. Insulation of the type used on the tanks is used for this purpose. I

From the foregoing it will be apparent that the particular carrier construction could be modified in detail without departing from the spirit of the invention.

Accordingly, the scope of invention is determined by the appended claims.

We claim:

1. In bulk fluid carrier construction wherein the temperature of the cargo may vary from the ambient temperature of the carrier, the carrier having a hull, the combination with said carrier of (1) plural aligned holds within the hull, each said hold including (2) one tank which extends substantially fully abeam the carrier and is spaced on all sides from said hold (3) means fixed to the floor of the hold anchoring said tank including (a) vertically aligned tank slide and (b) foundation assemblies in longitudinal and transverse coextension of the bottom of the tank, the assemblies each being fixed respectively to tank and floor, raising the tank above the floor,

() a plurality of pins extending through respective foundation and slide members (d) both said foundation and slide members having aligned pin-engaging apertures (e) the apertures of the slides being of greater dimension than the apertures of the corresponding foundations, whereby controlled expanding and contracting movements of tank relative to foundation may occur upon cargo temperature variation.

2. The combination according to claim 1 including:

(4) anti-friction means interposed between respective foundation and slide members an in coextension thereof, I

(a) each said anti-friction means being apertured as the foundation member, permitting movement to the slide in varying relation of said slide to the anti-friction means and foundation member.

3. The combination according to claim 1 in which the tank carries exterior insulation which is substantially less in thickness than the space defined by hold and tank exterior.

4. The combination of claim 1 in which the tank bottom forms a dihedral, the center line of which is aligned with the keelson of the carrier,

and in which corresponding tank slide and foundation assemblies comprise:

(a) at least one assembly which is disposed along the center line and in coextension of the tank, (b) at least one other assembly which is in transverse coextension of the tank, the respective assemblies intersecting at the bottom center of the tank.

5. The combination according to claim 4 in which the tank carries exterior insulation which is substanatially less in thickness than the space defined by tank exterior and hold.

6. In bulk fluid carrier construction wherein the temperature of the cargo fluid may vary from the ambient temperature of the carrier, the improvement comprising:

(1) an outer hull and an (2) inner hull spaced from the outer hull, said inner hull defining (3) at least one hold (4) a tank confined within the hold and resting in spaced relation to the inner hull,

(a) the bottom of said tank defining a dihedral contour, the center line of which is aligned with the ships keel;

(5) subjacent means of dihedral conformation anchoring the tank in expansion-contraction, wedging re lation to the bottom of the hold including (a) tank slides fixed to the bottom of said tank in longitudinal and transverse coextension of same,

(i) at least one longitudinal slide being fixed adjacent the apex of the dihedral bottom and (ii) at least one transverse slide intersecting the said first longitudinal slide in transverse coextension of the tank;

(6) corresponding tank foundation assemblies fixed to the floor of the inner hull, raising the tank above same;

(a) said foundation assemblies and slides defining corresponding plural apertures (7) a plurality of projections extending into slide and foundation apertures,

(12) the apertures of most slides being of greater dimension than the outer dimension of corresponding projections, uniting the respective slide and foundation assemblies in limited moving relation. 4

7. The combination according to claim 6, the tank and foundation assemblies further comprising:

supplemental tank slide and foundation assemblies disposed intermediate the ends and sides of the tank (1) each assembly including complemental aligned apertures (2) and freely movable pins seated within the apertures all such slide apertures being of greater area than the apertures of the corresponding foundation member.

8. The combination of claim 6 in which the respective slide apertures are of progressively greater lateral dimension from the center outwardly.

9. The combination according to claim 6 in which the tank carries exterior insulation which is substantially less in thickness than the space defined by tank exterior and hold.

References Cited in the file of this patent UNITED STATES PATENTS 97,787 Marshall Dec. 14, 1869 1,986,132 Bigelow Jan. 1, 1935 2,030,881 Knight Feb. 18, 1936 2,241,822 Marsh May 13, 1941 2,520,883 Kornemann Aug. 29, 1950 2,600,015 McLaughlin June 10, 1952 2,746,578 Bromeley May 22, 1956 2,896,416 Henry July 28, 1959 2,905,352 Henry Sept. 22, 1959 2,920,850 Campbell Jan. 12, 1960 2,954,003 Farrell Sept, 27, 1960 FOREIGN PATENTS 667,215 Great Britain Feb. 27, 1952 1,174,820 France Nov. 10, 1958 220,768 Australia Mar. 13, 1959 813,621 Great Britain May 21, 1959 1,206,930 France Aug. 31, 1959