USRE39721E1 - Discharge outlet for double wall containment tank assembly - Google Patents

Abstract

A discharge outlet is provided for attachment to a double wall containment tank assembly having an inner tank and an outer containment vessel. The discharge outlet includes a conduit fluidically connected to the fluid receiving chamber of the inner tank and extending exteriorly of the outer containment vessel, a flexible annular sealing member positioned between the inner tank and the outer containment vessel, and couplers for attaching the sealing member to the inner tank and the outer vessel in surrounding relationship to the conduit. The containment area between the two tanks which is designed fro containing spills from the inner tank is thereby fluidically isolated form the access opening through which the conduit passes.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention concerns a discharge outlet for use with a double wall tank assembly used for storing and dispensing large quantities of liquid. More particularly, it is concerned with a sealing boot for the discharge outlet which enables the liquid to be dispensed through openings in the side walls of the inner tank and outer vessel of the double wall tank assembly.

2. Description of the Prior Art

Storage of liquid in bulk is well known, and has evolved in importance due to environmental concerns over the escape of chemicals. In the past, it was common to store chemicals underground in large tanks where gravity was used to fill the vessels and the contents were periodically pumped for use. However, the problems associated with leading underground storage tanks has increased the usage of above ground storage tanks. Typically, one or more above-ground vessels have been placed in a “tank farm” where a concrete pad and berm help to contain and capture any problem. Rainwater received in the containment area must be monitored and treated if leakage is detected. This has proven very expensive, as the rainwater represents a large volume of liquid even though the leakage is isolated.

As a result, storage containers have been developed which include a double walled construction. Examples of containment tanks utilizing such construction are shown in U.S. Pat. Nos. 5,287,986 to Frost and U.S. Pat. No. 5,333,752 to Harding, Jr. While the double walled construction therein is an improvement over single walled tanks, they require filling and discharge to be accomplished from atop the tanks. This requires extra energy to be expended in pumping the liquid. The need to prevent leakage from a double walled containment tank assembly has thus not heretofore permitted effective discharge openings through the sidewalls of the component inner and outer tanks. Thus, there has developed a need for a containment tank assembly which is capable of use in a variety of environments, minimizes, leakage, and has reduced energy demands.

SUMMARY OF THE INVENTION

These objects have largely been met through the discharge outlet and sealing boot of the present invention. That is to say, the present invention effectively seals openings provided in the sidewalls of a containment tank assembly having an inner tank and an outer vessel. Moreover, the discharge outlet includes a sealing boot which captures liquid which might leak into the containment area between the inner tank and outer vessel. Advantageously, the sealing boot is flexible and thus accommodates relative movement between the inner tank and outer vessel, such as may be encountered by expansion of the inner tank during filling and external forces applied to the outer vessel.

The discharge outlet of the present invention broadly includes an inner tank flange assembly, an outer vessel flange assembly, and a sealing boot interconnecting the two flange assemblies, piping or conduit is preferably provided which extends from the inner flange assembly exteriorly of the outer vessel for attachment of a valve, piping or the like to effect the transfer of liquid from the tank. The sealing boot is preferably of a flexible material and is provided in the shape of a tire, whereby liquid leaking may be readily visually detected and repair of the inner tank assembly may be effected without deterioration of the containment capabilities of the double wall tank assembly. The piping of the discharge outlet, which is positioned relatively near the bottom of the side of the double wall tank assembly, may be further provided with additional piping interiorly of the inner tank and include a pipe opening near the bottom wall of the inner tank, thereby facilitating removal of most of the liquid within the inner tank when it is desired to be emptied.

These and other advantages of the discharge outlet of the present invention will be readily appreciated by those skilled in the art with reference to the drawings and the following description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a exploded view of a double wall containment tank assembly, showing the opening in the outer vessel for receiving the discharge outlet positioned relatively low on the side thereof;

FIG. 2 is a perspective view of the double wall containment tank assembly shown inFIG. 1 with the inner tank nested in the outer vessel and showing anchor assemblies for holding the double wall containment tank assembly against movement relative to the supporting surface;

FIG. 3 is an enlarged, vertical sectional view taken throughline3—3 ofFIG. 2 showing the discharge outlet mounted on the double wall containment tank assembly; and

FIG. 4 is an exploded view of the discharge outlet hereof.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to the drawing, adischarge outlet10 in accordance with the present invention is provided for mounting as part of a double wallcontainment tank assembly12 used for bulk storage of liquids. The double wallcontainment tank assembly12 includes aninner tank14, anouter vessel16, and a plurality ofanchor assemblies18 for securing thetank assembly12 to a pad or other supportingsurface20. The details of the structure of thetank assembly12 are further described in my U.S. Patent Application entitled Containment Tank Assembly filed contemporaneously herewith as application Ser. No. 09/519,323 filed Mar. 6, 2000, the disclosure of which is incorporated herein by reference.

In greater detail, theinner tank14 includes alower section22, anupper section24 which extends radially outwardly oflower section22 and is connected thereto by a lip presenting a trough, and aroof26 which acts as a cover to define a liquid-receiving chamber28 therewithin. The lip includes a plurality of circumferentially spaced chutes to permit drainage from the trough back into the interior of thelower section22. A plurality ofupstanding lugs30 project upwardly from theroof26 for the attachment ofcables32 ofanchor assemblies18 thereto. Theanchor assemblies18 also includeanchors34 which are bolted into the supporting surface20 (such as a concrete pad) and connected to thecables32 byeyebolts36. Amanhole cover38 is interfitted into a manhole in theroof26 to permit access into the chamber28. Thelugs30 provide pairs of tie-down flanges40 and liftingflanges42, each provided with holes for the passage ofcables32 therethrough. An opening through the side of theupper section24 permits the attachment offill pipe44 thereto. In addition, theroof26 receivesvent46,filler inlet48, andlevel indicator50 thereon, the latter including a probe for determining the amount of the liquid in the chamber28. Thelower section22 includes a substantiallycylindrical sidewall52 and abottom wall58 which are joined at thelower perimeter60 of thesidewall52. Aport54 is provided in the cylindrical sidewall proximate to thelower perimeter60, with four surrounding circumferentially spaced bolt holes62 provided through theside wall52.

Theouter vessel16 includes a multifacetedlower wall portion64 and a substantially cylindricalupper wall portion66. Thelower wall portion64 includes a plurality of alternatingarcuate sections68 andchord sections70. Thelower wall portion64 tapers inwardly intransition area72 tocylindrical wall portion66, which lies closely adjacent thecylindrical sidewall52 when theinner tank14 is nested in theouter tank16. Theupper wall portion66 has an upper margin provided with a plurality ofnotches74 for receiving the chutes of theinner tank14 therein. Thearcuate sections68 are spaced from thecylindrical sidewall52 of theinner tank14 to define therebetween acontainment area76. An access opening78 is provided in one of thearcuate sections68 for receipt of thedischarge outlet10 therein, with a plurality of surrounding, circumferentially spaced holes80 for the receipt of the bolts therethrough. Aleak detection system82 may be mounted in thelower wall portion64 and include a probe extending downwardly into thecontainment area76 to detect the presence of liquid therein. Thebase wall84 connects to thelower wall portion64 and receives thebottom wall58 of theinner tank14 thereon. Both theinner tank14 and theouter vessel16 are rotationally molded of synthetic resin, such as high density linear polyethylene or cross-linked, high density polyethylene.

Thedischarge outlet10 includes aninner coupler assembly86, ancoupler flange assembly88, sealing boot90, andpiping92. The inner coupler assembly includes interior flange94 andintermediate flange96 which each include aring98 and aneck100, eachflange94 and96 having acentral opening102 to permit the flow of liquid therethrough.Annular gaskets104 and106 abut thecylindrical sidewall52 in sealing relationship thereto. Therings98 andgaskets104 and106 each includeapertures108 aligned in registry with the bolt holes62 in thecylindrical sidewall52 for the receipt of bolts110 therethrough. The bolts110 are secured by suitable nuts and washers.

The sealing boot90 is located in thecontainment area76 and preferably rotationally molded of synthetic resin such as either high density linear or low density polyethylene for flexibility. The sealing boot90 is provided in the shape of a tire, including a flatinner wall112 provided with surrounding, circumferentially spaced apertures114 for the receipt of bolts110 therethrough, and acentral hole56 for alignment in registry with theport54 and thecentral opening102 of theneck100. An circumferentially extending cup-shaped protrusion116 extends radially outwardly from the flatinner wall112, with flatouter wall118 extending radially inwardly therefrom in spaced, opposed relationship to flatinner wall112. The flatouter wall118 includes aninner margin120 having a transverse dimension D which is substantially the same as that of the access opening78 and smaller larger than the diameter of thecentral hole56 of the flatinner wall112. The sealing boot90 thus defines an annular, circumferentially extending channel122 which permits flexing of the boot90 and captures liquid leaking past the inner coupler assembly.

Theouter coupler assembly88 has an inner flange provided as semi-annular inner flange plate halves124 and126 positioned within the channel122,annular gaskets128 and130 sandwiching the flatouter wall118 therebetween, andouter flange plate132 for engagement against theexterior134 of the outer vessel. The inner flange plate halves124 and126 and theouter flange plate132 are preferably stainless steel or other corrosion resistant metal. The flatouter wall118, inner plate halves124 and126,gaskets128 and130, and outer flange plate include holes which are positioned in registry with the holes80 in theouter vessel16 for receipt of bolts136 therethrough. The bolts136 are secured in place by suitable nuts and washers as shown inFIGS. 3 and 4. Thegaskets104 and106 and also128 and130 are preferably elastomeric, and provided of a chemically resistant natural or synthetic rubber material.

The piping92 is preferably of a chemical resistant synthetic resin material such as polyvinyl chloride and provides a conduit for the passage of liquid in the chamber28 out of thecontainment tank assembly12. The piping12 includes adischarge tube138 having an inner end which is preferably chemically welded to theneck100 of theintermediate flange96 and an outer end which receives aconnection flange140 for the attachment of further piping or a discharge valve to control the flow of liquid from thechamber76. Aninner tube142 extends into thechamber76 and has one end which is preferably chemically welded to theneck100 of interior flange94 and another end which receives thereonelbow144. Theelbow144 is oriented downwardly and apickup pipe146 is connected at one end thereto, thepickup pipe146 having an open,lower end148 adjacent the bottom wall for providing an intake into thepipeline92 for the discharge of liquid therethrough.

In use, the sealing boot90 and the access opening78 of the outer vessel are trimmed to fit with the flange plate halves124,126 andouter flange plate132. The flange plate halves124,126 are placed in the channel122 with the gaskets positioned as shown in FIG.3 and the bolts136 are inserted and tightened. Theinner tank14 is lowered into theouter vessel14 in nesting relationship with the chutes received in the inner notches and theport54 aligned with theaccess opening78. Theinner tank14 is then preloaded, and theport54 is trimmed to receive theinner flange assembly86. Theinner tube142,elbow144 andpickup pipe146 are installed into theinner flange assembly86 mounted on thecylindrical sidewall52 to permit liquid to flow through thecentral opening102. Thedischarge tube138 withconnection flange140 is then chemically welded to theneck100 ofintermediate flange96, and a control valve such as a ball valve or further piping is attached to the connection flange to permit filling of the chamber28.

Thedischarge outlet10 thus effectively permits theinner tank14 to be emptied of liquid through gravity rather than pumping, because the integrity of thecontainment area76 is preserved by the sealing boot90. The boot90 is sufficiently flexible to permit limited relative movement between theinner tank14 and theouter vessel16 due to seismic events, wind forces or thermal expansion. If liquid begins to leak from theinner tank14 through theinner flange assembly86, the leakage is nonetheless contained within the channel122 and can be readily visually observed. Other leaking from theinner tank14 is confined to thecontainment area76 between theinner tank14 andouter vessel16, such that even if the leakage rises above the access opening78 in the side of theouter vessel16, it does not escape.

Although preferred forms of the invention have been described above, it is to be recognized that such disclosure is by way of illustration only, and should not be utilized in a limiting sense in interpreting the scope of the present invention. Obvious modifications to the exemplary embodiments, as hereinabove set forth, could be readily made by those skilled in the art without departing from the spirit of the present invention.

The inventor hereby states his intent to rely on the doctrine of equivalents to determine and assess the reasonably fair scope of his invention as pertains to any apparatus not materially departing from but outside the literal scope of the invention as set out in the following claims.

Claims (36)

1. A discharge outlet for a double walled containment tank having an inner tank having a chamber for receiving liquid therein and a port for the passage of liquid therethrough, and an outer containment vessel having an access opening aligned with the port, the inner tank and the outer containment vessel defining a containment area therebetween, said discharge outlet comprising:

a conduit fluidically coupled to the inner tank;

a flexible, annular sealing member positioned between the inner tank and the outer containment vessel in substantial alignment with the port and the access opening in surrounding relationship to said conduit, said sealing member presenting a pair of opposed holes, one of said holes being of substantially greater diameter than the other of said holes;

a first coupler for connecting said sealing member to the inner tank around the port; and

a second coupler for connecting said sealing member to the outer containment vessel around the access opening and thereby fluidically isolating the containment area from the access opening.

2. A discharge outlet as set forth inclaim 1, wherein said sealing member includes a circumferentially extending cup-shaped protrusion.

3. A discharge outlet as set forth inclaim 2, wherein said sealing member is a flexible synthetic resin material.

4. A discharge outlet as set forth inclaim 3, wherein said sealing member includes a substantially flat inner wall extending radially inwardly from said protrusion and having a central said smaller diameter hole therein for permitting the passage of liquid therethrough.

5. A discharge outlet as set forth inclaim 4, wherein said first coupler includes an inner flange positioned in the chamber and an outer flange positioned in the containment area for receiving a wall of the inner tank therebetween, each of said inner flange and intermediate outer flanges having a central opening for the passage of liquid therethrough.

6. A discharge outlet as set forth inclaim 5, wherein said conduit includes a discharge tube fluidically connected to said intermediate flange and having a length sufficient to extend exteriorly of the outer vessel.

7. A discharge outlet as set forth inclaim 6, wherein said conduit includes an inner tube fluidically connected to said inner flange.

8. A discharge outlet as set forth inclaim 3, wherein said sealing member includes a substantially flat outer wall extending radially inwardly from said protrusion and having an inner margin.

9. A discharge outlet as set forth inclaim 8, wherein said inner margin is spaced outwardly from said conduit.

10. A discharge outlet as set forth inclaim 3, wherein said second coupler includes an inner flange plate positioned in said channel .

11. A discharge outlet as set forth inclaim 10, wherein said inner flange is provided as two semi-annular flange plate halves.

12. A discharge outlet as set forth inclaim 11, wherein said second coupler includes an outer flange plate and positioned relatively exteriorly of said flat outer wall .

13. A double walled containment tank assembly comprising:

an inner tank having a chamber for receiving liquid therein and a port for the passage of liquid therethrough;

an outer containment vessel having an access opening aligned with the port, the inner tank and the outer containment vessel defining a containment area therebetween; and

a discharge outlet, said discharge outlet including:

a conduit fluidically coupled to said inner tank;

a flexible, annular sealing member positioned between said inner tank and said outer containment vessel in substantial alignment with said port and said access opening in surrounding relationship to said conduit, said sealing member presenting a pair of opposed holes, one of said holes being of substantially greater diameter than the other of said holes;

a first coupler for connecting said sealing member to said inner tank around said port; and

a second coupler for connecting said sealing member to said outer containment vessel around said access opening and thereby fluidically isolating said containment area from said access opening.

14. A containment tank as set forth inclaim 13, wherein said sealing member includes a circumferentially extending cup-shaped protrusion.

15. A containment tank as set forth inclaim 14, wherein said sealing member is a flexible synthetic resin material.

16. A containment tank as set forth inclaim 15, wherein said sealing member includes a substantially flat inner wall extending radially inwardly from said protrusion and having a central said smaller diameter hole therein for permitting the passage of liquid therethrough.

17. A containment tank as set forth inclaim 16, wherein said first coupler includes an inner flange positioned in said chamber and an outer flange positioned in the containment area for receiving a wall of said inner tank therebetween, each of said inner flange and intermediate outer flanges having a central opening for the passage of liquid therethrough.

18. A containment tank as set forth inclaim 17, wherein said conduit includes a discharge tube fluidically connected to said intermediate flange and having a length sufficient to extend exteriorly of said outer vessel.

19. A containment tank as set forth inclaim 18, wherein said conduit includes an inner tube fluidically connected to said inner flange and extending into said chamber adjacent a bottom wall of said inner tank.

20. A containment tank as set forth inclaim 15, wherein said sealing member includes a substantially flat outer wall extending radially inwardly from said protrusion and having an inner margin, said outer wall being positioned proximate said outer vessel.

21. A containment tank as set forth inclaim 20, wherein said inner margin is spaced outwardly from said conduit.

22. A containment tank as set forth inclaim 15, wherein said second coupler includes an inner flange plate positioned in said channel .

23. A containment tank as set forth inclaim 22, wherein said inner flange is provided as two semi-annular flange plate halves.

24. A containment tank as set forth inclaim 23, wherein said second coupler includes an outer flange plate and positioned relatively exteriorly of said flat outer wall and proximate said outer vessel .

25. A discharge outlet for a double walled containment tank having an inner tank provided with a chamber for receiving liquid therein and having a side wall provided with a port therein for passage of liquid therethrough, and an outer containment vessel having a wall portion provided with an access opening having a predetermined area and positioned generally across from the port in the side wall of the inner tank, the inner tank and the outer containment vessel defining a containment area therebetween, said discharge outlet comprising:

a conduit coupled to the port in the side wall of the inner tank for fluidic communication of the conduit with the inner tank;

said conduit extending through the access opening in the outer containment vessel;

a flexible annular boot member positioned in surrounding relationship to the conduit and having opposed annular end portions, each of said annular end portions defining a hole, one of said holes having a diameter greater than the diameter of the other of said holes;

a first coupler sealingly coupling the end portion of the boot member having said larger diameter hole to the outer containment vessel around the access opening therein; and

a second coupler sealingly coupling the end portion of the boot member having said smaller diameter hole adjacent to the conduit in spaced relationship from the first coupler,

the area of said access opening being greater than the cross-sectional area of that part of the conduit extending through said access opening,

whereby said boot member prevents leakage of liquid from the double walled containment tank that may collect in the containment area.

26. A discharge outlet as set forth inclaim 25, wherein the boot member is sufficiently flexible to permit limited relative movement between the inner tank and the outer containment vessel.

27. A discharge outlet as set forth inclaim 25, wherein said first coupler is annular and spaced radially outwardly of said conduit to permit limited relative movement between the conduit and the containment vessel.

28. A discharge outlet as set forth inclaim 25, wherein said other opposed annular end portion of the boot member is sealingly coupled to the conduit adjacent the port in the side wall of the inner tank.

29. A discharge outlet as set forth inclaim 25, wherein said second coupler sealingly couples said other end portion to said inner tank.

30. A discharge outlet as set forth inclaim 25, wherein said boot member includes a circumferentially extending cup-shaped protrusion.

31. A discharge outlet as set forth inclaim 30, wherein said cup-shaped protrusion has a maximum cross-sectional area greater than the area of the access opening.

32. A discharge outlet as set forth inclaim 25, wherein said boot member is of a flexible synthetic resin material.

33. A discharge outlet as set forth inclaim 25, said boot member having first and second outer end portions, wherein said first outer end portion of the boot member has a unitary first annular wall, a first annular gasket between the side wall portion of the outer containment vessel and the first annular wall of the boot member to prevent leakage of fluid from the containment area of the tank through said access opening of the containment vessel.

34. A discharge outlet as set forth inclaim 33, wherein said second end portion of the boot member has a unitary second annular wall and a second annular gasket surrounding the conduit and sealingly engaging the second annular wall of the boot member to prevent leakage of fluid from the containment area between the inner tank and the containment vessel.

35. A discharge outlet as set forth inclaim 25, said annular boot being located within said containment area.

36. A discharge outlet as set forth inclaim 25, said inner tank having a base, an upright sidewall, and an upper end, said outer containment vessel having a base, an upright sidewall opposed to said inner tank sidewall, and an upper end, said discharge outlet located closer to said inner tank and containment vessel bases than said inner containment and containment vessel upper ends.

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