Tank cover with composite cover panels

Abstract

A tank or other form of container or vessel for holding fluids being treated or the like is provided with a removable cover. The cover is formed of a number of panels of a composite material including a thermoset synthetic resin and a reinforcing fiber material typically fiberglass. The panels are formed by a pultrusion process and are of sufficient length to extend between the end walls of the tank as single units. The panels may be made of any suitable width and depth and require no welding or joining to form a single panel width.

Description

This application claims the benefit of U.S. Provisional Patent Application Ser. No. 60/508,512 filed Oct. 3, 2003.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to covers for tanks or similar vessels for treatment of fluids of various types and to removable cover panels for use in such covers. More particularly, the cover panels are made of a composite material in the form of a fiberglass reinforced synthetic resin.

2. Description of Prior Art

Tanks or other forms of containers or vessels for various types of liquids being stored, treated or processed were for a number of years provided with fixed, non-removable roofs. These fixed roofs were mounted on and supported by internal support structure in the form of beam grids mounted in upper portions of the tanks. Early types of tank covers were usually made of wood, and later versions were made from fiberglass, stainless steel, aluminum, glass-impregnated fabrics and other materials.

The prior fixed tank covers were not removable by conventional methods for service or repair of the interior of the tank. In addition, the prior metal tank covers were exposed to moisture and humidity. As a consequence, those metal tank covers which were made from metals other than stainless steel eventually corroded over a period of service life. Those fixed cover systems made of stainless steel usually were expensive and heavy. Typically, they were in the form of corrugated steel and were thus not a suitable surface for service crews to safely walk or stand on.

More recently, removable tank covers have been provided, usually composed of a number of panels. Clean air standards, environmental concerns, emissions controls and other similar governmental regulations have required that the removable tank covers permit no more than specified limits of emissions.

So far as is known, currently available tank covers are provided by aluminum fabricators, who fabricate tank cover panels from an assembly of several extruded panels. Aluminum panels of this type have had to be formed by assembly of several extruded panel parts together to form a single panel. Further, panel parts formed by the aluminum extrusion process have been limited in size by the size of the billets from which each part was extruded. Typically, these billets have been approximately 10″ in diameter and would thus yield an extruded part approximately 8″-9″ in width and a few inches in depth. Therefore, in order for an aluminum fabricator to make a panel of a width of more than eight or nine inches, a number of extruded parts have had to be joined together in a side-by-side fashion to make one single panel. The individual panels then could be nested together across the lateral extent of the top surface of the tank to form a tank cover.

Once the individual panels have been nested together, they must be affixed to one another. This was, so far as is known, done by stitch welding each panel to the adjacent panel along its length. In some cases spot welding may have been used to reduce costs, but sealing of the tank to reduce vapor or gas envisions was reduced. Once welded, lateral stiffening members were welded to the panel along with the panel termination caps. Welding of the aluminum members was undesirable, since the areas of the aluminum adjacent to the welded area lost a considerable portion of their strength due to the heat generated during the welding process. In addition, if the tank were made of steel and the cover of aluminum, undesirable galvanic action between the two different metals when any fluid was between them was also a problem.

SUMMARY OF THE INVENTION

Briefly, the present invention provides a tank cover for covering an opening in a process tank. The tank cover is formed from a suitable number of fiberglass synthetic resin tank cover panels. The panels take the form of a central span which has a defined width and extends longitudinally a distance to span the opening from one end to another. A side wall is integrally formed with the central span extending downwardly from each side of the central span. Each of the side walls has a transversely extending connector leg for a mating fit with a connector leg of an adjacent panel. Each side wall further has an inwardly extending shelf formed in an intermediate portion of its downward extent to receive a stiffener member to be mounted in the panel for increased strength and load bearing.

The panels in the tank cover provide easy removability, sealing to reduce the potential release of volatile organic compounds (VOC), and a capability of spanning the process tank without necessarily requiring the use of an under panel structural support system of beams or the like. The panels are integrally formed as continuous, one piece parts through a die with a pultrusion process. Various synthetic resin technologies may be used to provide the resin which is reinforced by the fiberglass to form the panels according to the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

A better understanding of the present invention can be obtained when the detailed description set forth below is reviewed in conjunction with the accompanying drawings, in which:

FIG. 1 is partially exploded isometric view of a tank cover system and tank cover panels according to the present invention;

FIG. 2 is a front elevation view of the tank cover system and panels of FIG. 1;

FIG. 3 is a cross-sectional view taken along the lines 3-3 of FIG. 2;

FIG. 4 is a side elevation view, taken partly in cross-section, of tank cover panel end mounting structure according to the present invention for mounting the cover panels to and end wall of a tank;

FIG. 5 is a cross-sectional view taken along the lines 5-5 of FIG. 3 of a first type of cover panel according to the present invention;

FIG. 6 is a cross-sectional view of a second type of cover panel according to the present invention;

FIG. 7 is a cross-sectional view of a stiffener beam for the cover panels of the present invention, taken along the line 7-7 of either FIG. 5 or FIG. 6;

FIGS. 8, 9 and 10 are exploded views illustrating assembly of panels of FIGS. 6 and 7 together in order to form a tank cover according to the present invention; and

FIG. 11 is a side elevation view, taken partly in cross-section of tank cover panel mounting structure according to the present invention for mounting a cover panel to a side wall of a tank.

To better understand the invention, we shall carry out the detailed description of some of the modalities of the same, shown in the drawings with illustrative but not limited purposes, attached to the description herein.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the drawings, the letter S designates generally a cover system for covering a tank T, or some other form of container or other vessel. The cover system S is of the type known as a top mount cover, and is composed of a number of cover panels P which are assembled together to form the cover system S. The tank T may be of a wide variety of types, for waste treatment, petrochemicals or various other types of liquids or slurries being processed, treated or stored. As will be set forth, the individual panels P are integrally formed of a suitable grade of fiberglass reinforced thermoset or synthetic resin with a process known as pultrusion. The panels P are integrally formed in the configurations shown and are specially shaped for easy removability, sealing and long spanning capability. The panels P are shown in the preferred embodiment as forming parts of a cover for process tanks which contain openings to allow access into the interior of the tank for service, maintenance and the like.

The panels P according to the present invention take two forms or types, a first or female panel F and a second or male panel M. Each of the panels P is of a one-piece construction of a predetermined width of lateral extent or span formed of a fiberglass reinforced plastic or synthetic resin, often referred to in the industry as FRP. The synthetic resin used is of preferably a thermoset resin and may be, for example, based on one of a number of types of synthetic resin technologies, such as isophthalic polyester; vinylester; or NSF/Standard 61 grade polyester, and is reinforced with a suitable fiber such as fiberglass. It should be understood that other types of synthetic resins may be used as well. Further, the synthetic resins may be made from a fire-retardant or non-fire retardant polyester, if desired. The panels P are capable of being made to a desired length or span that, depending upon the size of the tank opening, may span the end-to-end extent of such an opening. The panels P of fiber-reinforced plastic are also of a predetermined lateral width or extent of several times that of the panel parts formed from aluminum billets presently available.

The first or female panel F (FIGS. 1, 2 and 5) includes a central upper span or panel portion 10 extending to provide in the preferred embodiment a lateral coverage on the order of about 24 to 30 inches or more. The panel F also includes a pair of integrally formed, downwardly extending, side walls 12 and 14 beneath a sealing groove step 16 and 18 integrally formed at either end 10a and 10b of the central panel 10. The side walls 12 and 14 include an integrally formed, transversely outwardly extending connector legs 20 and 22, respectively.

A retainer ledge or rim 24 is formed extending upwardly at an outer end 20a and 22a at each of the connector legs 20 and 22. An inwardly extending shelf or ledge 26 is formed in each of the side walls 12 and 14 at an intermediate position along their vertical extent. The shelves or ledges 26 extend inwardly beneath the central span 10 of the panel F to receive and support transversely extending stiffeners being used, channels, bars B or the like. The spacing of the shelf 26 from a lower surface 28 of each of the sealing grooves 16 and 18 defines the vertical extent or depth of the stiffening beam, channel, tube or bar B. Depending on the span of the tank and the loading capability requirements for the panels P, the vertical extent of the side walls 12 and 14 as well as the location of the shelf 26 may be adjusted to increase the depth of the panels and to accommodate deeper stiffening beams B for increased span lengths and load-bearing capabilities for the panels F.

The first panel F also includes a suitable number of laterally spaced load transfer struts 30 extending downwardly beneath the central span or width 10 at suitably spaced positions. The struts 30 are preferably in the form of inverted T shapes with vertical portions 32 and lateral load transfer horizontal portions 34. It should be understood that other shapes may be used as well for the struts 30. The lateral horizontal portions 34 rest on an upper surface 36 of the stiffener beam B to distribute or transfer load from the central span 10 of the panel F to the stiffener beam B. The sealing groove steps 16 and 18 are slightly recessed from an upper surface 10c of the central span 10 to accommodate and connect with the adjacent second or male panel M, as will be set forth. A gasket receiving groove 38 is formed extending along the length of the span or extent of the panel F to receive a suitable seal, such as a bulb gasket 40 (FIGS. 8-10).

The second or male panel M (FIGS. 1, 2 and 6) includes a central upper span or panel portion 50 extending to provide in the preferred embodiment a lateral coverage of on the order of 30 inches. The panel M also includes a pair of integrally formed, downwardly extending side walls 52 and 54 integrally formed end portions 50a and 50b of the central panel 50. The side walls 52 and 54 include an integrally formed, transversely inwardly extending connector legs 60 and 62, respectively.

A set of inwardly extending shelves or ledges 66 and 68 are formed in each of the side walls 52 and 54 on intermediate portions along their vertical extent. The shelves or ledges 66 and 68 extend inwardly beneath the central span 50 of the panels M to receive and support a transversely extending stiffener beam, channel or bar B of the type set forth above. The vertical extent of the side walls 52 and 54 as well as the spacing of the shelf 66 from the lower shelf 68 beneath the central portion 50 of the second panel M define the vertical extent or depth of the stiffening beam or channel B. Again, as with the first panel F, depending upon the tank spanning and load capability requirements for the panel M, the location of shelves 66 and 68 may be adjusted to increase the depth of the panels and to accommodate deeper stiffener beams for increased span lengths and load bearing capabilities for the panels P.

The second panel M also includes a suitable number of laterally spaced load transfer struts 70 extending downwardly beneath the central span or width 50. The struts 70 are preferably in the form of inverted T-shapes with a vertical portions 72 and lateral load transfer horizontal portions 74. It should be understood that other shapes may be used for the struts 70, as well. The lateral horizontal portions 74 rest on upper surface 36 of the stiffener beams B to transfer or distribute load from the central span 50 to the stiffener beam B. The second panel M includes an outwardly extending connector flange 78 integrally formed at each outer end 50a and 50b of the central span 50. A downwardly extending lip or ledge 80 is formed along the extent of the connector flange 78. The flanges 78 and lips 80 of the panels are adapted to engage and fit with the sealing groove steps 16 and 18 of adjacent panels F (FIGS. 8-10) and compress the gasket or seal 40 along the span of the panels F and M across the tank T. This fitting engagement serves to seal the seams between the panels F and M along their extent across the tank T and inhibit the emission or leakage of undesirable vapors or gasses from the interior of the tank.T into the environment.

The first or female panel F includes the outward protruding legs 20 and 22 on either side of the panel over the entire length of the panel F. The second or male panel M contains the inward protruding legs 60 and 62 that extend down the entire length of the panel M. When the panels F and M are brought together, the inward protruding legs 60 and 62 engage with and fit atop of the outward protruding legs 20 and 22 of the adjacent panels F. This alternating pattern of panels M and F takes place as many times as necessary to fully cover the opening of the open top tank(s) or vessel(s).

Each of the panels F and M is provided with end flashing E, as shown in FIGS. 3 and 4. The end flashing E is also formed by the pultrusion process from a thermoset fiberglass reinforced synthetic resin or plastic of the type used in the panels F and M. The end flashing E includes a foot or base 90 extending outwardly from an upright or end wall 92. A lower surface 94 of the foot or base 90 has a sealing groove 96 formed along its extent in order to receive a suitable seal 97, such as a bulb gasket, to form a seal between the end flashing E and an end wall W of the tank T. This seal 97 formed between the end flashing E and the wall W protects against emission or leakage of undesirable vapors present in the tank T.

A handle grip 98 is formed at an upper end 100 of the end wall 92 of end flashing E and includes an integrally formed lifting handle 102 extending downwardly to a lower grip portion 104. The grip portion 104 extends from the lifting handle 102 for a service crew member to grasp the end flashing E to lift, place or remove a panel P. The end flashing E is attached to the end wall W by a suitable fastener, such as a concrete anchor, stainless steel screw, welded-on stud or the like.

The stiffener beam B is also preferably formed from a thermoset fiberglass reinforced synthetic resin of the type mentioned above. The stiffener beam B can be located along the extent of the panels M over the tank where required for support framing at a location where a hatch is needed in one of the panels, or for lateral bracing, as needed or for both. The stiffener beam B is shown in the preferred embodiment as a C-shaped channel, although it should be understood that other beam shapes or forms may be used. Examples include I-beams, tubes, rods, bars, Z-members and the like.

A stiffener beam B at the end of each panel P is attached to the end flashing E, as shown in FIG. 4 through the use of suitable fasteners such as stainless steel bolts 106 and connector nuts 108, with sealing washers or gaskets 110 also preferably included. The C-shaped stiffener beam shown in the drawings includes a central web or upright 112 and two laterally extending flanges 114 and 116 at upper and lower ends, respectively.

Side flashing S (FIG. 11) is provided along a modified panel M-1 for each of the side walls L of the tank T extending the full length over the tank T between the end walls W. The panel M-1 is a version of the panel M without flange 78 and 80 along one of the outer ends of the central span 50.

The side flashing S includes a foot or base 120 extending outwardly from an upright or end wall 122. A lower surface 124 of the foot or base 120 has a sealing groove 126 formed along its extent in order to receive a suitable seal 127, such as a bulb gasket, to form a seal between the side flashing S and the side wall L of the tank T. The seal 127 between the side flashing S and the side wall L protects against emission or leakage of various undesirable vapors which may be present in the tank T. A handle grip 128 is formed at an upper end 130 of the end wall 122 of the side flashing S and includes an integrally formed lifting handle 132 extending downwardly to a lower grip portion 134. The grip portion 134 extends from the lifting handle 132 for a service crew member to grasp the side flashing S and to lift, place or remove the panel P. The side flashing S is attached to the side wall L by a suitable fastener 136 such as a concrete anchor, stainless steel screw, welded-on stud or the like.

The fiberglass reinforced synthetic resin tank covers and panels according to the present invention have a better strength to weight ratio than the metallic units. In addition, they may be fire retardant, and non-conductive and can be anti-static by some standards. Fiberglass systems can be made out of several resin technologies, which enable it to provide varying degrees of corrosion resistance, structural properties, and fire and smoke generation properties. Panels can also be produced and certified to meet government standards for potable water.

The fiberglass reinforced synthetic resin used in the tank covers and panels with the present invention is corrosion resistant to some of the harshest of chemicals, where metallic systems simply cannot maintain their structural integrity.

By using fiberglass reinforced plastic to construct tank covers with the present invention, there is also no need or concern for isolating the cover itself from concrete or steel. A consideration with aluminum systems is galvanic corrosion that occurs when contact is made between dissimilar metals causing the degradation of the base materials. Therefore, total isolation between the dissimilar metals must be provided. With fiberglass reinforced plastics, which are of a non-conductive material, no such concerns are present regarding galvanic action.

It is expected that a thermoset pultruded deck panel unit, alternating cover system according to the present invention can be capable of clear spanning up to 20 ft. or more without necessarily requiring the use of an under panel structural support system such as beams. Furthermore with the flexibility of the design, additional depth can be easily added to the panel profile to increase the span and loading capability.

The cover panel system according to the present invention has specifically shaped alternating male and female panels that can, depending on tank size, clear span a vessel or tank opening to create an enclosed environment. Sealing between the underside of the panel and the tank is accomplished by means of gasketing the perimeter and intermediate panels. The removable cover system thus reduces the potential release of volatile organic compounds (VOC) into the air and therefore minimize the impact on the environment.

It should also be noted that the panels P, while originally made to be rectangular in shape as shown in the drawings, can be readily altered by post fabrication to make trapezoids or triangles in order to cover rounded, irregular or non-rectangular shaped vessels. Male and terminating panels are fastened to walls of existing structures (i.e. concrete tank walls, steel tank rims, existing bridges, trusses, etc.) by utilizing concrete anchors, welded on studs, stainless steel screws and the like through the end flashing E and side flashing S.

The present invention affords a unitary one piece design that requires no welding or joining of materials to define the width of the panel. The panels P can be placed in a corrosive environment, and there is no need to isolate the cover system from the structure to which it is to be attached, as there is no galvanic corrosion. The alternating panel arrangement with stiffener beams does not require a beam grid to the support panel in the event that attachments, hatches or are required for the tank.

The thermoset fiberglass reinforced plastic or synthetic resin panels of the present invention are non-conductive, anti-static, fire retardant, self extinguishing and exhibit lower thermal expansion and contraction rates than metal. The panels P may, if desired, be provided with an anti-skid, walkable top surface. The panels can also be easily field modified with conventional wood working tools, such as saws, hammers, etc., at field installation sites.

The invention has been sufficiently described so that a person with average knowledge in the matter may reproduce and obtain the results mentioned in the invention herein Nonetheless, any skilled person in the field of technique, subject of the invention herein, may carry out modifications not described in the request herein, to apply these modifications to a determined structure, or in the manufacturing process of the same, requires the claimed matter in the following claims; such structures shall be covered within the scope of the invention.

It should be noted and understood that there can be improvements and modifications made of the present invention described in detail above without departing from the spirit or scope of the invention as set forth in the accompanying claims.

Claims

1. A fiberglass reinforced synthetic resin tank cover panel for covering an opening in a process tank, comprising:

a central span having a defined width and extending longitudinally a distance to span the opening from one end to another;

a side wall integrally formed extending downwardly from the central span on each side thereof;

each of the side walls having a transversely extending connector leg for a mating fit with a connector leg of another panel;

each side wall further having an inwardly extending shelf formed in an intermediate portion of its downward extent to receive a stiffener member to be mounted therein.

2. The cover panel of claim 1, wherein the side wall on each side of the central span is integrally formed with the central span.

3. The cover panel of claim 1, wherein the transversely extending connector leg on the side wall is integrally formed with the side wall.

4. The cover panel of claim 3, wherein the connector leg extends outwardly from the side wall in a direction away from the central span.

5. The cover panel of claim 4, further including a retainer ledge formed on the connector leg at an end opposite the side wall.

6. The cover panel of claim 3, wherein the connector leg extends inwardly from the side wall in a direction beneath the central span.

7. The cover panel of claim 1, wherein the central span has a walking surface formed across an upper surface thereof.

8. The cover panel of claim 1, further including:

a step formed in the central span at each side thereof.

9. The cover panel of claim 8, further including:

a sealing groove formed in the step at each side of the central span and adapted to receive a sealing member therein.

10. The cover panel of claim 9, wherein the step and sealing groove are coextensive with the longitudinal extent of the central span.

11. The cover panel of claim 1, further including:

at least one strut formed in a lower surface of the central span.

12. The cover panel of claim 1, wherein the width of the central span is co-extensive with the width of the panel.

13. The cover panel of claim 1, further including:

end flashing mounted extending across the width of the central span for closing the space beneath the central span between the side walls.

14. The cover panel of claim 1, wherein the end flashing has a mounting flange extending outwardly therefrom for mounting on a wall of the process tank.

15. The cover panel of claim 14, further including a sealing groove formed in a lower surface of the mounting flange and adapted to receive a sealing member therein.

16. The cover panel of claim 1, wherein the end flashing has a hand grip formed therewith.

17. The cover panel of claim 1, further including:

side flashing mounted extending along one of the side walls for mounting the cover panel on a wall of the process tank.

18. The cover panel of claim 17, wherein the side flashing has a mounting flange extending outwardly therefrom for mounting the cover panel on the process tank wall.

19. The cover panel of claim 18, further including a sealing groove formed in a lower surface of the mounting flange and adapted to receive a sealing member therein.

20. The cover panel of claim 18, wherein the side flashing has a hand grip formed therewith.

21. The cover panel of claim 1, further including a stiffener beam mounted on the shelf of the side walls and extending therebetween for support of the central span.

22. A tank cover for a process tank formed of a plurality of fiberglass reinforced synthetic resin panels, comprising:

each of said panels comprising:

a central span having a defined width and extending longitudinally a distance to span the opening from one end to another;

a side wall integrally formed extending downwardly from the central span on each side thereon;

the side wall having a transversely extending connector leg for a mating fit with a connector leg of another panel;

each side wall further having an inwardly extending shelf formed in an intermediate portion of its downward extent to receive a stiffener member to be mounted therein.