Discharge outlet for double wall containment tank assembly

Information

  • Patent Grant
  • 6318581
  • Patent Number
    6,318,581
  • Date Filed
    Monday, March 6, 2000
    24 years ago
  • Date Issued
    Tuesday, November 20, 2001
    23 years ago
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 in

FIG. 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 through line


3





3


of

FIG. 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, a discharge outlet


10


in accordance with the present invention is provided for mounting as part of a double wall containment tank assembly


12


used for bulk storage of liquids. The double wall containment tank assembly


12


includes an inner tank


14


, an outer vessel


16


, and a plurality of anchor assemblies


18


for securing the tank assembly


12


to a pad or other supporting surface


20


. The details of the structure of the tank assembly


12


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, the inner tank


14


includes a lower section


22


, an upper section


24


which extends radially outwardly of lower section


22


and is connected thereto by a lip presenting a trough, and a roof


26


which acts as a cover to define a liquid-receiving chamber


28


therewithin. The lip includes a plurality of circumferentially spaced chutes to permit drainage from the trough back into the interior of the lower section


22


. A plurality of upstanding lugs


30


project upwardly from the roof


26


for the attachment of cables


32


of anchor assemblies


18


thereto. The anchor assemblies


18


also include anchors


34


which are bolted into the supporting surface


20


(such as a concrete pad) and connected to the cables


32


by eyebolts


36


. A manhole cover


38


is interfitted into a manhole in the roof


26


to permit access into the chamber


28


. The lugs


30


provide pairs of tie-down flanges


40


and lifting flanges


42


, each provided with holes for the passage of cables


32


therethrough. An opening through the side of the upper section


24


permits the attachment of fill pipe


44


thereto. In addition, the roof


26


receives vent


46


, filler inlet


48


, and level indicator


50


thereon, the latter including a probe for determining the amount of the liquid in the chamber


28


. The lower section


22


includes a substantially cylindrical sidewall


52


and a bottom wall


58


which are joined at the lower perimeter


60


of the sidewall


52


. A port


54


is provided in the cylindrical sidewall proximate to the lower perimeter


60


, with four surrounding circumferentially spaced bolt holes


62


provided through the side wall


52


.




The outer vessel


16


includes a multifaceted lower wall portion


64


and a substantially cylindrical upper wall portion


66


. The lower wall portion


64


includes a plurality of alternating arcuate sections


68


and chord sections


70


. The lower wall portion


64


tapers inwardly in transition area


72


to cylindrical wall portion


66


, which lies closely adjacent the cylindrical sidewall


52


when the inner tank


14


is nested in the outer tank


16


. The upper wall portion


66


has an upper margin provided with a plurality of notches


74


for receiving the chutes of the inner tank


14


therein. The arcuate sections


68


are spaced from the cylindrical sidewall


52


of the inner tank


14


to define therebetween a containment area


76


. An access opening


78


is provided in one of the arcuate sections


68


for receipt of the discharge outlet


10


therein, with a plurality of surrounding, circumferentially spaced holes


80


for the receipt of the bolts therethrough. A leak detection system


82


may be mounted in the lower wall portion


64


and include a probe extending downwardly into the containment area


76


to detect the presence of liquid therein. The base wall


84


connects to the lower wall portion


64


and receives the bottom wall


58


of the inner tank


14


thereon. Both the inner tank


14


and the outer vessel


16


are rotationally molded of synthetic resin, such as high density linear polyethylene or cross-linked, high density polyethylene.




The discharge outlet


10


includes an inner coupler assembly


86


, an coupler flange assembly


88


, sealing boot


90


, and piping


92


. The inner coupler assembly includes interior flange


94


and intermediate flange


96


which each include a ring


98


and a neck


100


, each flange


94


and


96


having a central opening


102


to permit the flow of liquid therethrough. Annular gaskets


104


and


106


abut the cylindrical sidewall


52


in sealing relationship thereto. The rings


98


and gaskets


104


and


106


each include apertures


108


aligned in registry with the bolt holes


62


in the cylindrical sidewall


52


for the receipt of bolts


110


therethrough. The bolts


110


are secured by suitable nuts and washers.




The sealing boot


90


is located in the containment area


76


and preferably rotationally molded of synthetic resin such as either high density linear or low density polyethylene for flexibility. The sealing boot


90


is provided in the shape of a tire, including a flat inner wall


112


provided with surrounding, circumferentially spaced apertures


114


for the receipt of bolts


110


therethrough, and a central hole


56


for alignment in registry with the port


54


and the central opening


102


of the neck


100


. An circumferentially extending cup-shaped protrusion


116


extends radially outwardly from the flat inner wall


112


, with flat outer wall


118


extending radially inwardly therefrom in spaced, opposed relationship to flat inner wall


112


. The flat outer wall


118


includes an inner margin


120


having a transverse dimension D which is substantially the same as that of the access opening


78


and smaller than the diameter of the central hole


56


of the flat inner wall


112


. The sealing boot


90


thus defines an annular, circumferentially extending channel


122


which permits flexing of the boot


90


and captures liquid leaking past the inner coupler assembly.




The outer coupler assembly


88


has an inner flange provided as semi-annular inner flange plate halves


124


and


126


positioned within the channel


122


, annular gaskets


128


and


130


sandwiching the flat outer wall


118


therebetween, and outer flange plate


132


for engagement against the exterior


134


of the outer vessel. The inner flange plate halves


124


and


126


and the outer flange plate


132


are preferably stainless steel or other corrosion resistant metal. The flat outer wall


118


, inner plate halves


124


and


126


, gaskets


128


and


130


, and outer flange plate include holes which are positioned in registry with the holes


80


in the outer vessel


16


for receipt of bolts


136


therethrough. The bolts


136


are secured in place by suitable nuts and washers as shown in

FIGS. 3 and 4

. The gaskets


104


and


106


and also


128


and


130


are preferably elastomeric, and provided of a chemically resistant natural or synthetic rubber material.




The piping


92


is preferably of a chemical resistant synthetic resin material such as polyvinyl chloride and provides a conduit for the passage of liquid in the chamber


28


out of the containment tank assembly


12


. The piping


12


includes a discharge tube


138


having an inner end which is preferably chemically welded to the neck


100


of the intermediate flange


96


and an outer end which receives a connection flange


140


for the attachment of further piping or a discharge valve to control the flow of liquid from the chamber


76


. An inner tube


142


extends into the chamber


76


and has one end which is preferably chemically welded to the neck


100


of interior flange


94


and another end which receives thereon elbow


144


. The elbow


144


is oriented downwardly and a pickup pipe


146


is connected at one end thereto, the pickup pipe


146


having an open, lower end


148


adjacent the bottom wall for providing an intake into the pipeline


92


for the discharge of liquid therethrough.




In use, the sealing boot


90


and the access opening


78


of the outer vessel are trimmed to fit with the flange plate halves


124


,


126


and outer flange plate


132


. The flange plate halves


124


,


126


are placed in the channel


122


with the gaskets positioned as shown in FIG.


3


and the bolts


136


are inserted and tightened. The inner tank


14


is lowered into the outer vessel


14


in nesting relationship with the chutes received in the inner notches and the port


54


aligned with the access opening


78


. The inner tank


14


is then preloaded, and the port


54


is trimmed to receive the inner flange assembly


86


. The inner tube


142


, elbow


144


and pickup pipe


146


are installed into the inner flange assembly


86


mounted on the cylindrical sidewall


52


to permit liquid to flow through the central opening


102


. The discharge tube


138


with connection flange


140


is then chemically welded to the neck


100


of intermediate flange


96


, and a control valve such as a ball valve or further piping is attached to the connection flange to permit filling of the chamber


28


.




The discharge outlet


10


thus effectively permits the inner tank


14


to be emptied of liquid through gravity rather than pumping, because the integrity of the containment area


76


is preserved by the sealing boot


90


. The boot


90


is sufficiently flexible to permit limited relative movement between the inner tank


14


and the outer vessel


16


due to seismic events, wind forces or thermal expansion. If liquid begins to leak from the inner tank


14


through the inner flange assembly


86


, the leakage is nonetheless contained within the channel


122


and can be readily visually observed. Other leaking from the inner tank


14


is confined to the containment area


76


between the inner tank


14


and outer vessel


16


, such that even if the leakage rises above the access opening


78


in the side of the outer vessel


16


, 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
  • 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; 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 in claim 1, wherein said sealing member includes a circumferentially extending cup-shaped protrusion.
  • 3. A discharge outlet as set forth in claim 2, wherein said sealing member is a flexible synthetic resin material.
  • 4. A discharge outlet as set forth in claim 3, wherein said sealing member includes a substantially flat inner wall extending radially inwardly from said protrusion and having a central hole therein for permitting the passage of liquid therethrough.
  • 5. A discharge outlet as set forth in claim 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 flange having a central opening for the passage of liquid therethrough.
  • 6. A discharge outlet as set forth in claim 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 in claim 6, wherein said conduit includes an inner tube fluidically connected to said inner flange.
  • 8. A discharge outlet as set forth in claim 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 in claim 8, wherein said inner margin is spaced outwardly from said conduit.
  • 10. A discharge outlet as set forth in claim 3, wherein said second coupler includes an inner flange plate positioned in said channel.
  • 11. A discharge outlet as set forth in claim 10, wherein said inner flange is provided as two semi-annular flange plate halves.
  • 12. A discharge outlet as set forth in claim 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; 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 in claim 13, wherein said sealing member includes a circumferentially extending cup-shaped protrusion.
  • 15. A containment tank as set forth in claim 14, wherein said sealing member is a flexible synthetic resin material.
  • 16. A containment tank as set forth in claim 15, wherein said sealing member includes a substantially flat inner wall extending radially inwardly from said protrusion and having a central hole therein for permitting the passage of liquid therethrough.
  • 17. A containment tank as set forth in claim 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 flange having a central opening for the passage of liquid therethrough.
  • 18. A containment tank as set forth in claim 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 in claim 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 in claim 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 in claim 20, wherein said inner margin is spaced outwardly from said conduit.
  • 22. A containment tank as set forth in claim 15, wherein said second coupler includes an inner flange plate positioned in said channel.
  • 23. A containment tank as set forth in claim 22, wherein said inner flange is provided as two semi-annular flange plate halves.
  • 24. A containment tank as set forth in claim 23, wherein said second coupler includes an outer flange plate and positioned relatively exteriorly of said flat outer wall and proximate said outer vessel.
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