US3374918A - Floating deck for storage tank - Google Patents

Description

March 26, 1968 c. CREITH 3,374,913

FLOATING DECK FOR STORAGE TANK Fi led Jan. 25, 1966 2 Sheets-Sheet 1 FIG- I INVENTOR. LOU 6. CR1. T H

[16-2 Bl/wgmw ATTOPNFV March 26, 1968 L. c. CREITH 3,374,918

FLOATING DECK FOR STORAGE TANK Filed Jan. 25, 1966 2 Sheets-Sheet 5/ Z0 A; A, 117;; '1 f "WWW -3Z INVENTOR. LOU C CHE/TH dm u A T TORNE Y United States Patent 3,374,918 FLOATING DECK FOR STORAGE TANK Lou C. Creith, Allentown, Pa., assignor to Olin Mathieson Chemical Corporation, a corporation of Viriginia Filed Jan. 25, 1966, Ser. No. 522,900 4 Claims. (Cl. 22026) ABSTRACT OF THE DISCLOSURE A floating deck for use in liquid storage tanks is provided in which a plurality of individually buoyant pans to keep the deck afloat. In areas of the deck not occupied by said pans, sheets of metal are provided to avoid vaporization.

This invention relates in general to an improvement in floating decks for use within a liquid storage tank, and more particularly to such a deck having improved flotability apparatus.

Floating decks of many types and forms have been proposed and used in tanks designed for the storage of various liquids. Such a deck may form the roof of the particular storage tank, or may be a separate member within a tank having a fixed roof. In either case, the deck floats substantially horizontally on or slightly above the surface of the liquid stored and moves upwardly and downwardly with the surface as the volume of the liquid stored varies. Thus, protection is afforded to the liquid stored from the environment above the deck; additionally, evaporation from the area below the deck is retarded.

One form of such a deck which has been proposed comprises a framework covered by a generally flat material, the framework and covering being supported by floats attached to, and spaced below, the framework. While such a deck achieves many of the advantages of a floating deck, it is relatively expensive to fabricate and to erect within the storage tank to be protected.

According to the instant invention, it has been found that all of the desired advantages of a floating deck may be achieved in a relatively inexpensive manner by incorporating into the flat covering itself the members yielding the flotation features. This may be accomplished in general by providing as a portion of the covering of the framework a plurality of individually buoyant pans designed in shape and number so as to yield the required flotation.

A further feature of the instant invention involves the design of the members forming the framework so as to provide below the deck a plurality of pockets formed' between the surface of the liquid stored and the covering of the deck, which pockets serve to trap any vapors formed above the surface of the liquid stored. In this way, any leak which may exist in a given area of the deck is isolated from the remaining portions of the deck.

It is accordingly a principal object of the instant invention to provide a new and improved floating deck for use in a storage tank containing a liquid.

A further object of this invention is to provide such a deck which is relatively inexpensive in construction and easy to install.

It is a still further object of this invention to provide such a floating deck comprising a substantially horizontal framework, at least one individually buoyant pan supported by said framework, the remainder of the framework being covered by a material impervious and impermeable to the liquid stored, the pan being effective to cause the framework, when in use, to float with the covering material above the level of the liquid stored.

Other objects and advantages will become apparent to those skilled in the art as a detailed description of an 3,374,918 Patented Mar. 26, 1968 exemplary embodiment proceeds with reference to the drawings which form a part hereof and in which:

FIGURE 1 is a perspective view of one form of tank in which a deck according to the instant invention may be employed, with a portion of the tank Wall shown broken away to expose the deck in the interior thereof;

FIGURE 2 is a plan view of a portion of the framework of the instant floating deck;

FIGURE 3 is a perspective view of a pan which may be employed with the instant deck;

FIGURE 4 is a cross-sectional view through a portion of the instant deck, showing in particular the connection to the framework of a pan and the covering material; and

FIGURE 5 is a cross-sectional view similar to FIG- URE 4, illustrating a modification of the instant invention.

While it is to be understood that the instant floating deck may be employed in any type or shape of vertical walled storage tank, FIGURE 1 illustrates by way of example a floating deck 10 in use in a cylindrical storage tank 11 having a fixed roof 12 and a center pole 13, the tank 11 containing a liquid 14. The floating deck 10 effectively covers the surface of the liquid 14 by a framework supporting a number of buoyant pans 20 and substantially flat sheets 21. The specific construction of the deck will be detailed below, it being understood that all components of the deck disclosed are of a material impervious and impermeable to the particular liquid stored. Certain materials may, for example, be a light metal, plastic material, or fabric coated with a suitable material such as a plastic material.

Considering first the construction of the framework which supports all other components, reference is had to FIGURE 2. The framework, designated generally by 15, consists of a peripheral ring 22 and a grid of beams 23 and girders 24. The peripheral ring 22 conforms in configuration to the perimeter of the tank 11, but is spaced laterally inwardly from the tank walls. Within ring 22 are a plurality of spaced parallel coplanar beams 23 and a plurality of spaced parallel coplanar girders 24, shown perpendicular to beams 23. For reasons to become evident, the ring 22, beams 23, and girders 24 are all preferably of an L-shaped or T-shaped cross-section, notched as necessary at their intersections.

The beams 23 and girders 24 traverse the entire area enclosed by ring 22 and are interconnected in any suitable manner at intersecting points 25, as by bolts or rivets. Similarly, the beams 23 are suitably attached to the ring 22 at points of intersection 26. To form a seal between the ring 22 and the interior Walls of the tank 11, while allowing for irregularities in the tank walls as the deck moves upwardly or downwardly, a suitable flexible but resilient sealing means 27 is attached about the periphery of ring 22.

Into certain of the rectangles formed by beams 23 and girders 24 are inserted a plurality of the pans 20, one of which is illustrated in detail in FIGURE 3. The pan 20 is designed to be individually buoyant, and comprises. a curved bottom portion 30 with integral upwardly sloping side walls 31 and integral flanges 32 extending laterally from the upper edges of the sides 31. With a given size of deck 10, the required number of pans 20 may be readily calculated so as to insure the flotability of the deck 10. For example, for a deck 60 feet in diameter, it has been found that 50 pans 4" deep, 96" long by 17" wide and approximately .040" thick aluminum yields the required flotability when employing an aluminum framework and covering of suitable dimensions.

In use, the bottom 30 of pan 20 extends downwardly into the liquid stored, with the flanges 32 being attached to the framework. To cover the portion of the framework in the areas thereof not supporting the pans, suitably shaped sheets 21 are employed. As illustrated in FIGURE 1, these sheets 21, along with the pans 20, effectively cover the entire area of the deck 10.

Referring now to FIGURE 4, the attachment of pans 20 and sheets 21 to framework may be observed. While FIGURE 4 represents a cross-section through the deck taken parallel to a beam 23, it will be appreciated that the construction is such that a cross-section taken parallel to a girder 24 would be analogous. Supported on the intersection of two beams 23 and two girders 24 is a pan 20, with its flanges 32 being supported above the upper portion of girder 24 or beam 23. Adjacent portions of framework 15 are in turn covered by sheets 21, portions thereof overlying the flanges 32 of pan 20, The overlying portions of beams 23, girders 24, flanges 32, and sheets 21 may then all be secured together in any suitable manner, as by a bolt or rivet at 25. To insure a seal-tight relationship at such connections, an additional strip 40 may be employed atop the sheets 21, the strip 40 being shown as of a channeLshaped section. Additionally, a suitable glue or adhesive may be used between the opposing portions of overlying elements to assure a seal-tight relationship.

Employing the same type of attachment indicated above, the open, upper end of the pans may, if so desired, be covered by sheets similar to sheets 21 to prevent any condensation or foreign materials from settling in pans 20. This relationship is illustrated in the simpli fied view of FIGURE 5, wherein a pan 20', sheets 21', and strips 40 corresponding to the analogous elements 20, 21, and 40, respectively, are shown. A rectangular covering sheet 50 may be employed to close off the upper end of pan 20', the sheets 21 and channels 40' being oriented atop the ends of sheet 50. The remainder of the attachment would, of course, be identical to that disclosed with respect to FIGURE 4.

Referring again to FIGURE 4, an additional feature of the instant invention may be seen. As indicated hereinbefore, the ring 22, beams 23, and girders 24 are preferably of an L-shaped or T-shaped cross-section, Thus, the downwardly projecting portions of these members, such as 41 and 42 illustrated in FIGURE 4, define vertical webs extending downwardly into the liquid stored. As these webs form a grid corresponding to the grid of the framework, the webs form a plurality of pockets above the surface 43 of the liquid 14, below the underside of the deck 10. Such a formation of a plurality of pockets assures that a great portion of the vapor above the surface 43 of liquid 14 will be trapped below the deck 10 even in the event of a leak at a particular area of the deck.

-While not shown, it will be clear to those skilled in the art that ancillary equipment normally employed with floating decks may be incorporated in the design here disclosed. For example, a plurality of downwardly extending feet may be attached to the framework to space the deck 10 above the bottom of the storage tank 11 when empty, to facilitate cleaning and maintenance. Addition: ally devices for draining away liquids condensed on the upper surface of the deck, gauging and sampling openings, manhole passages, and vertical cables to prevent rotation of the deck may be incorporated as desired.

It is to be understood that the invention is not limited to the illustrations described and shown herein which are deemed to be merely illustrative of the best modes of 4' carrying out the invention, and which are susceptible of modifications of form, size, arrangement of parts and detail of operation, but rather is intended to encompass all such modifications which are within the spirit and scope of the invention as set forth in the appended claims.

What is claimed is:

1. A floating deck for use in a storage tank containing a liquid, comprising (A) a substantially horizontal framework,

(B) a plurality of individual open top buoyant pans supported by said framework and mounted to extend downwardly into the liquid stored, said pans consisting of:

(1) a curved bottom portion adapted to extend downwardly into the liquid,

(2) integral sides sloping upwardly from said bottom, and

(3) integral flanges extending laterally from the upper ends of said sides,

(C) said framework in the areas thereof not supporting said pans only being covered by a substantially flat material impervious to the liquid stored,

(D) said pans being of suflicient rigidity and shape retentivity to cause said framework in use to float with said material above the level of the liquid stored.

2. A floating deck according to claim 1 wherein said framework includes vertical web portions extending downwardly into the liquid stored defining a plurality of pockets below said framework in which vapor above the liquid is trapped.

3. A floating deck according to claim 1 wherein said framework comprises (A) a peripheral frame,

(B) a plurality of spaced parallel coplanar beams attached to said peripheral frame,

(C) said frame and each of said beams including a vertical web adapted to extend downwardly into the liquid stored,

whereby the surface of the liquid is completely covered and vapor above the liquid is trapped below said framework in pockets formed between said frame and said beams.

4. A floating deck according to claim 3 further including a plurality of cross-brace girders attached to said peripheral frame and each including a vertical web adapted to extend downwardly into the liquid stored, whereby, when in use, vapor above the liquid stored is trapped in pockets delimited in part by said vertical webs of said girders.

References Cited UNITED STATES PATENTS 1,674,039 6/1928 Glass 22026 2,036,372 4/ 1936 Sto-ugh 22026 3,029,971 4/1962 Reynolds 22026 3,104,775 9/ 1963 Champagnat 22026 FOREIGN PATENTS 1,241,869 8/ 1960 France. 1,247,440 10/ 1960 France.

THERON E. CONDON, Primary Examiner.

I. R. GARRETT, Assistant Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,374,918 March 26, 1968 Lou C. Creith It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as shown below:

lines 20 and 21, and column 2, lines 63 and 67,

"flotability", each occurrence, should read floatability Column 1, lines 44 and 48, "flotation", each occurrence, should read floatation Column 3, lines 56 and 57, after "Additionally" insert a comma.

Column 1,

Signed and sealed this 29th day of July 1969.

(SEAL) Attest:

Edward M. Fletcher, Ir.

Attesting Officer Commissioner of Patents WILLIAM E. SCHUYLER, JR.

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