IL44547A - Floating cover for a liquid storage tank - Google Patents

Description

a»>fi3 naomtV a»o nay ηι »io»a FIXATING COVER FOR A LIQUID STORAGE TANK FIELD OF THE INVENTION The present invention relates to a floating cover for liquid storage tanks . and, more particularly, relates to improvements in f 1 oati ng. seal s of the type . s uppor ted upon the surface of volatile hydrocarbon liquids contained within bulk s torage tanks . ' _ ·." "■'■ ■■ ■„■ .' BACKGROUND OF THE I VENTIO ■ " -' The lost of valuable hydrocarbons to atmosphere as a result of surface evaporation due to differential vapo pressures and solar heat are of considerable economic importanc and constitute a significant percentage of atmospheric pollutio and smog .

In an effort to control this wastage, efforts have , been made to introduce floating seals which are generally of metallic construction utilizing eithe steel or aluminum . . ., ·. fabrications supported upon floats which may be foam filled as a precaution against puncture. The field assembly and installation of such floating seal is very costly, particularly when requi red · to . be installed in an exi s ti ng tank , I n addition, troubles are experienced in the operation of such floating ■ seals. In particular, they represent a hazard from static electricity which has to be neutralized by. extensive bonding and earthing devices. The mechanical.' i ntegrity must be perfect and buoyancy may be lost through a single started fastening. · This integrity has also been known to be breached by electrolyti corrosion along the joints. The weight of such a floating seal is very considerable and supporting legs have become 'deformed due to unequal loading imposed by the lack of flatness in the. tank bottom; The recti ffcati on of such defects is very costl .since the tank must first be drained and purged, and the lost of use during repair represents a further costl loss.

OBJECTS OF THIS INVENTION It is an object of the present invention to eliminate these objections and hazards while introducing considerable • economi es , pa rti cul arly the cost of on-site installations.

It is a further object of the present, i nventi on to provide a monolithic unit panel in' the shape of ah isosceles triangle such that plurality of identical units may be easily, assembled together to form a planar platform of a generally . ci cular shape.

It is still a further object of. this invention to provide a plurality of such panel s , made enti rely of cellular foam plastics, wherein no metallic components-. or' fastenings are used for interconnecting the panels.

STATEMENT OF THE INVENTION The present invention therefore relates to a floating cover for liquid storage tanks which comprises: a generally circular planar platform formed of a plurality of concentric groups of interconnected panels made of cellular foam plastics, the panels being identically shaped in the form of an isosceles triangle, each panel including, along one side, a male engaging profile and, along the other side, a female engaging profile, both profiles having correspohdi ngly shaped cross-sections whereby adjacent panels may be inter-' connected in side-by-side relation to form a concentric group of panels; inter-engaging profile means are provi ded .on the , base of each panel to connect the bases of panels , of one concentric group with the bases of panels of a radially ad j a cent concen.tri c group .

■ . In the preferred form of the invention, the bases forming the periphery of the circular platform includes end panels equipped with sealing means to provide an air-tight engagement with the inner wall of the storage tank.

Other objects and further scope of applicability of the presefit invention will become apparent from the detailed description given hereinafter; it should be understood, however, that the detailed description, while indicating a preferred embodiment of the invention, is given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a perspective view of a storage tank with a broken wall to show the floating cover therein made in accordance with. the present Invention; .

Figure 2 is a perspective enlarged view of two panels used in the platform of the present invention; Figure 3 is a schematic representation of a quarter of a platform having six concentric groups of panels; Figure 4 is a cross-sectional view taken along lines 4- 4 of Figure 3; Figure 5 is a cross-sectional view taken along lines 5- 5 of Fig. 3; Figure 6 is a cross-sectional view taken along lines 6- 6 of Fig.

Figure 7 is a cross-sectional view taken along lines 7- 7 of Fig.3.

Referring now more particularly to Figure 1 , the numeral 10 generally designates a storage tank having a cylindrical vertical wall 12, a bottom 14 and a roof 15.

Inside tank 10 a floating cover 16 constructed in accordance with an embodiment of the present invention is shown supported on legs 17. (no fluid being shown in the tank) .

The floating cover 16 consists of a generally circular planar platform formed of a. series of concentric groups (six being shown in Figure 3 as 20a, 20b, 20c, 20d, 20e, 20f) of interconnected panels 22, such as shown in Figure 2.

These panels 22 are preferably moulded from a rigid hard skinned polyurethane closed cell foamed material of low cubic density ¾nd possessing fire resistant and self-extinguishing properties. Such material is inert to carbon-hydrate solvents and can be used in direct contact with the fluid upon which it floats while possessing adequate mechanical strength combined with a surface hardness adequate to be used as a working platform.

The ci cumference of the assembled platform is of a diameter slightly less than that of the internal diameter of the tank wall 12, such that a clearance is left which allows the platform to move with the fluid level without coming into contact with the tank wall ; this also allows for a lack of circularity on the part of the cylindrical wall . This clearance between wall and platform is closed, however, by an elastomeric seal i ng, member 26, which is attached to the periphery of the floating platform 16 as hereinafter explained.

The. panels 22 are identically shaped in the form of an isosceles triangle with two equal sides 28 and 30 and a base 32. The panels may be planar or include reinforcing ridges 33 such as shown in Figures 2 and 4.

To form the first concentric group 20a, a series of these re- f ab ri ca ted panels 22 are i ter-connected in side-by- side relation. This is accomplished by providing, along one side of a panel , a -fcemiale engaging profile, such as tongue 34 and,, along the other side of the panel , a female engaging profile, such as groove 36. This first concentric group of panels is assembled so that it may freely slide along a column 24, which serves to support the roof 15 of the tank. One way is i ,j 1 us trated . i n Figure 5 and consists in attaching to the apex'of each panel a circular member 38, made of similar plastic material , to which is attached by means of suitable securing means 40, a sealing canvas 42 of neoprene or urethane, I, to thereby provide an air-tight engagement with column 24.

The second concentric group 20b of the platform is formed in a similar fashion by interconnecting panels 22 in side-by side relation (see Figure 4) . However, this second group 20b of panels is attached to the first group 20a of panels by their bases 32 which also include nter-engaging profiles which may be of a tong-and-groove arrangement 41-43, similar to the one described above for the side-by-side engagement of panels. The inter-engagement of the bases could also be accomplished by a tong and groove profile in each base, longitudinally thereof, whereby the base engagement . of the panels could be carried out by merely inverting one panel relative to an adjacent one.

Concentric groups 20c, 20d, 20e and 20f are assembled and nterconnected in a similar fashion.

The tong and groove profiles are preferably .shaped to provide an air-tight engagement once .they are locked to one another. Figure 7 exemplifies one way which consists in providing the profiles with further flange portions .41a and 46a ' In another embodiment, the profiles could be further secured with a suitable adhesive.

One important characterist c of the present invention is that the panels may be assembled one to the other within the tank. The geometry of the panels takes . the form of a triangle isosceles of such a size that any given plurality of panels may be assembled together to produce a generally circular platform of given size inside the tank. One preferred size of a panel 22 is a triangle with a 16" base and with 4'8" sides. The dimension of the base of the right triangle is such that it will pass thr.ough a standard 24 inch diam. circular access manhole of a tank thereby enabling all the material necessary to complete the floating cover for any size of tank to be introduced through the standard manhole of any approved A.P.I. (American Petroleum Institute) tank.

The platform 16\further includes a plurality of end panels 44 which are made of the same plastic material as panel 22 and which are provided with profile means 46 to correspond ng ly engage the profile 41 of the base on each panel . As can be seen in Figure 3, the end panel 44 is adapted to receive the bases of six panels.

The sealing member 26 is formed of foam plastic material 48 enclosed within a nylon coated cover 50. This sealing member has a portion fixedly attached (not shown) to the end of the platform, which portion extends over the bases of panels 22 and the end panels 44.

The panels may be shaped to accommodate the supporting legs 17; recesses 52 may be provided in the ridges 33 to receive the upper part of the legs 17.. With the type of plastic material used, it is possible to cut through the panel at recesses 52 whereby the platform may be vertically adjusted relative to the legs 17. Figure 3 shows a manhole 54 which may be provided on the platform to allow equipment, instruments or the like to pass through the platform.

Claims (6)

44547 li

1. In a floating cover for a liquid storage tank, a generally circular plana^ platform formed of a plurality of concentric groups of interconnected panels made of cellular foam plastics, said panels being identically shaped in the form of an isosceles triangle with two equal sides arid a base; each said panel including, along one side, a male engaging profile and, along the other side, a female engaging profile, said profiles having correspondingly shaped cross-sections whereby adjacent panels' may be interconnected in side-by-side relation to form a concentric group; inter-engaging profile means on said bases to connect the bases of panels of one concentric group with the bases of panels of a radially adjacent concentric group P

2. In a floating cover as defined in claim 1 , further comprising end panels ci rcumferenti al ly disposed on said platform, said end panels having profiles for correspondingly engaging the inter-engaging profile means of the bases of the outmost radially disposed concentric group of panels.

3. In a floating cover as defined in claim 1 , wherein said panels are moulded from a rigid hard skinned polyurethene closed cell foamed material from low cubic density.

4. In a floating cover as defined in claim 2, sealing means disposed ci rcumferenti al ly on said end panels for providing an airtight engagement between the platform and a storage tank wal 1.

5. In a floating cover as defined in claim 1 , wherein each said panel includes reinforcing ridges on one surface thereof. Uk5k7/2

6. In a floating cover oa defined in claim 5» further eompriaing reoeaaed holes in aaid ridges to receive supporting lege for aaid platfora. 7· A floating cover for a liquid storage tank substantially aa herein described with reference to and aa illustrated in the accompanying drawings. Attorney for pp icants.