AU2013101126A4 - Double skinned & walled bunded tank - Google Patents

Abstract

The present invention describes a tank for storage of fluid comprising a body having first and second skins. The first skin is arranged to define a first volume for receiving and containing the fluid and the second skin defines a second volume for accommodating the first skin and first volume. The first and second skins are spaced apart by a void. The tank further comprises an outlet disposed at an underside of the body, for selective filling and drainage of the fluid; and an outlet assembly receivable by the outlet, wherein the outlet assembly seals with both skins. Fig. 10

Description

AUSTRALIA PATENTS ACT 1990 COMPLETE SPECIFICATION FOR AN INNOVATION PATENT (Original) APPLICATION NO: LODGED: COMPLETE SPECIFICATION LODGED: ACCEPTED: PUBLISHED: RELATED ART: NAME OF APPLICANT: Oilfield & Resource Rentals Pty Ltd ACTUAL INVENTORS: Patrick Hanna Patrick Joy ADDRESS FOR SERVICE: LORD AND COMPANY, Patent and Trade Mark Attorneys, of PO Box 530, West Perth, Western Australia, 6872, AUSTRALIA. INVENTION TITLE: "DOUBLE SKINNED & WALLED BUNDED TANK" The following Statement is a full description of this invention including the best method of performing it known to me/us: 2 TITLE "DOUBLE SKINNED & WALLED BUNDED TANK" FIELD OF THE INVENTION [0001] The present invention relates to a bunded tank with a double skinned wall. BACKGROUND [0002] It is a necessity for the oil and gas industry, amongst others, to have a method for storage and handling of fluid goods including liquids and gases. Many of these liquids and gases may be dangerous, and often corrosive, flammable or toxic. As such, there exists a high degree of regulation for the storage and handling of these dangerous goods. Storage and handling containers and methods used for dangerous goods have been developed to meet the stringent regulations applicable. [0003] A known container typically comprises a tank for storage of the dangerous goods. The tank itself would typically comply with all regulations and standards for the storage and handling of dangerous goods. Such compliance would be achieved through the material selected for construction of the tank, adequate space for signage indentifying the contents and a regular maintenance schedule, for example. However, a system for the containment of spills is also necessary. [0004] The area where a tank is located would typically require bunding to contain spills of liquids. Typical bunding comprises embankments or walls and a fluid impervious floor. Dangerous goods should be stored in these defined bunded areas. [0005] Some containers have removed the need for external bunding by introducing an intrinsic bund. This includes tanks with a double wall, which acts to contain spills similar to a typical bund that comprises an embankment, for example. A double wall, however, may introduce difficulties such as the drainage of spills or leaks that are trapped or contained within the double wall and draining the liquid stored in the tank. 2 [0006] Known tanks may be filled and emptied through a top portion of the tank. Other requirements necessary for normal operation in relation the tank require an operator to access the top portion. This includes, for example, inspection of the level of liquid inside the tank using a traditional dip stick. Due to the height of typical storage tanks, this introduces a fall risk, often necessitating the use of a harness or other fall arrest devices or methods. [0007] The present invention attempts to overcome at least in part the aforementioned disadvantages of previous dangerous goods storage and handling means. SUMMARY OF THE INVENTION [0008] In accordance with one aspect of the present invention there is provided a tank for storage of fluids comprising: a. a body having first and second skins; the first skin arranged to define a first volume for receiving and containing the fluid and the second skin defining a second volume for accommodating the first skin and first volume; wherein the first and second skins are spaced apart by a void; b. an outlet disposed at an underside of the body, for selective filling and drainage of the fluid; and c. an outlet assembly receivable in the outlet, the assembly being sealable with both skins. [0009] The tank may further comprise an airline valve with an operating mechanism within reach of an operator on ground level. [0010] The tank may further comprise a means for visual determination of the presence and level of contents in the void between the spaced apart first and second skins. [0011] The tank may further comprise a level indicator including a float and gauge for assessment and display of the level of the contents of the first volume of the tank. 3 [0012] The tank may be provided within a frame comprising a deluge system for the control or suppression of a fire. BRIEF DESCRIPTION OF DRAWINGS [0013] The present invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is an upper perspective view of the tank of the present invention provided within a frame; Figure 2 is a cross-sectional front view of the lower portion of the tank and frame of Figure 1; Figure 3 is a cross-sectional front view of the lower portion of the tank of Figure 2 with the outlet assembly removed; and Figure 4 is an upper perspective view of the tank of the present invention including a deluge system. DESCRIPTION OF A PREFERRED EMBODIMENT [0014] Referring to Figure 1, there is shown a vertical bunded tank 10, within a rectangular frame 12, in accordance with the present invention. The frame 12 may comprise apertures 18 on the top four corners. The frame 12 may further comprise 4-way forklift pockets 22 at the base. To operate in accordance with known forklift carrying methods, two forklift pockets 22 are provided on each of the four sides of the frame 12. Both the apertures 18 and the forklift pockets 22 enable, in use, the frame 12 to be either lifted from above or below. Lifting from below, for example using a forklift, is possible from any of the four sides through use of the 4-way forklift pockets 22. [0015] The upper, roof portion of the frame 12 comprises secured grating 16. The grating 16 includes a hatch 15 comprising two doors, shown here with one in an opened position and one in a closed position. The frame 12 further comprises a ladder 20. The frame 12 even further comprises a plate 14 onto which signage or placards may be fixed for identification of the contents of the tank 10 or other purposes as required. 4 [0016] In accordance with a preferred embodiment, the frame 12 also comprises a deluge system 54, as best seen in Figure 4. The deluge system 54 comprises piping 56 and at least one top spray nozzle 58. The deluge system 54 further comprises at least one bottom spray nozzle 60, (see Figure 2). In use, the deluge system 54 provides a means for a suppressant to be delivered to the exterior of the tank 10, through an inlet 32, for instance, for the suppression or control of a fire. [0017] Referring now to Figures 1 and 4, the tank 10 comprises a level gauge 42. The level gauge 42, in use, provides indication of the level of fluid within the tank 10. The level gauge 42 is viewable through a sight glass, which is preferably of a size to allow for the level gauge 42 to be removed if required. [0018] In accordance with a preferred embodiment of the present invention, the level gauge 42 is activated by and in connection with an arm 54 connected to a float 50 as best shown in Figure 2. In use, the float 50 rests on or near the surface of the contents of the tank to indicate the level of said contents at the level gauge 42. [0019] The tank 10 further comprises a body 21, a skirt 19 and a top dish 23. The skirt 19 may be releasably attached to the frame 12 by a suitable means such as through the use of bolts. The top dish 23 comprises a lid 24 enabling, in use, access to the interior of the tank 10 from the top dish 23 of the tanklO. Preferably, the lid 24 is of a size suitable for an operator to enter the tank 10 for cleaning or other necessities. [0020] The tank 10 further comprises an airline valve 26 comprising an operating mechanism 28 (shown here as a lever) located within reach of an operator on ground level. In use, the airline valve 26 may be operated through use of the operating mechanism 28 to equalise the pressure in the interior of the tank 10 during, for example, drainage of the tank 10. The tank 10 also comprises a pressure and vacuum relief valve 44. In use, this relief valve 44 automatically equalises, to atmospheric pressure, any created pressure or vacuum within the interior of the body 21 of the tank 10, which 5 exceeds predetermined tolerances. For manual operation of the relief valve 44, a handle 45 is provided in connection with the relief valve 44. Preferably, this manual operation handle 45 may be within or near reach of an operator on ground level, reducing the need for an operator to be positioned at the top dish 23 to operate the relief valve 44. [0021] The tank 10 may further comprise a dip stick (not shown) for an additional method of ascertaining the level of fluid inside the tank 10. The interior of the tank 10 may be accessed by the dip stick through an access point 25 in the top dish 23. [0022] With reference now to Figures 2 and 3, the walls of the tank 10 comprise a first (inner) skin 11 defining a first volume which is understood to typically hold the fluid. The walls of the tank 10 further comprise a second (outer) skin 13 defining second volume for accommodating the first skin and first volume. The first and second skins are spaced apart by a void 52, which surrounds a majority of the first skin 11. The second skin 13 may be seal welded to the tank 10 at the top dish 23 and at the skirt 19. [0023] A contents indicator 46 (see Figure 4) is provided on the outside of the second skin 13 for indication of the level of liquid inside the void 52 in the instance when, for example, the first skin 11 of the tank 10 becomes compromised. The contents indicator 46 comprises a transparent tube, in direct or indirect connection with the lowest point of the void 52, into which a portion of the leaked liquid may flow. It will be understood that any leaked liquid would flow to the contents indicator 46, under the effect of gravity. In use, an operator may visually inspect the transparent tube for the presence of any leaked liquid. The contents indicator 46 may further comprise a drain 48 and, in use, is utilised for the drainage of liquid within the void 52 and the contents indicator 46. The second skin 13 may comprise a vent 34 which, in use, is utilised to equalise the pressure inside the void 52 between the first skin 11 and second skin 13 during situations such as temperature change or the draining of the tank 10. [0024] The skirt 19 may be provided with holes 30 which provide a passage through the inner skin of the skirt 19. In use, any possible fluid content within the skirt 19 may pass 6 through the skirt 19, under gravity, to the void 52. As such, said fluid may be drained in the same manner as fluid in the void 52 through use of the drain 48. [0025] The underside of the tank 10 preferably comprises an outlet sealable with an outlet assembly 36 for, in use, both filling the tank 10 and releasing the contents of the tank 10. A sample valve 38 may extend from the outlet assembly 36. It will be understood that the outlet provides access from the exterior of the tank 10 to the interior or first volume. [0026] The outlet assembly 36 comprises a central cap 35 and an outer flange 39. Inuse, the central cap 35 fits to and seals with the first skin 11 and the outer flange 39 fits to and seals with the second skin 13. In this way, the outlet assembly 36 may adequately seal both skins 11 and 13 of the tank 10, and therefore seal the outlet, while provide access, when desired, to the interior or first volume of the tank. One or more gaskets 37 may be provided at the connection point of the outlet assembly 36 to the outlet for ensuring an adequate seal between said outlet assembly 36 and the tank 10. For example, a gasket may be provided between the first skin 11 and the central cap 35, and the second skin 13 and the outer flange 39. [0027] As seen in Figure 2, a containment system may be provided at the bottom of the tank 10 for the instance of a leak from both ends of the outlet assembly 36, both proximal and distal to the tank 10. The containment system may comprise two drip trays 40; one under the lowest point of the body of the tank 10 and another under the sample valve 38 at the distal end of the outlet assembly 36. [0028] In use, the tank 10 may be placed within the frame 12 or provided on its own. Within the frame 12, the tank 10 may be lifted or carried into a desired location. The frame 12 may be lifted and transported into a desired position through the use of a forklift. The four way forklift pockets 22 provided near the base of the frame 12 enable a forklift to be used from any of the four sides of the frame 12. The apertures 18 near each of the four corners on the top surface of the frame 12 provide a means for attachment of ropes, cables or other suitable material. In this way, the frame 12 may be suspended and 7 carried to a desired position through the use of a crane or other suitable mechanism. [0029] The secured grating 16 including the hatch 15 at the roof portion of the frame 12 may be used to restrict access to the upper of the tank 10. Through suitable means, such as a padlock, the hatch 15 may be locked. The hatch 15 in the secured grating 16 may also provide, when desired, access through the roof portion of the frame 12, to the upper of the tank 10. The roof portion of the frame 12 may be accessed by personnel using the ladder 20 provided on the frame 12. [0030] In the event of fire or a similar emergency situation in the vicinity of the tank 10 and frame 12, the deluge system 54 may be used. Suitable fire suppressant, for example, may be provided to the deluge system 54 through the inlet 32. The suppressant may pass through the piping 56 and exit the deluge system 54 through the top and bottom spray nozzles 58 and 60. Hence, the deluge system 54 may deliver the suppressant to the exterior of the tank 10 for the suppression or control of a fire. [0031] Both the lid 24 in the top dish 23 of the tank 10 and the outlet assembly 36 provide means for filling the tank 10 with desired fluids. The body 21 of the tank 10 provides a vessel capable of containing a large volume of fluids. In the instance of requiring access to the interior or the tank 10 for cleaning or other purposes, equipment or personnel may utilise the sufficiently sized lid 24. [0032] During the filling process, any unwanted pressure discrepancies, in both the first volume provided by the body 21 of the tank 10 or the void 52 between the first skin 11 and second skin 13, may be alleviated. The airline valve 26 in the top dish 23 of the tank 10 may be operated by personnel at ground level by using the operating mechanism 28. In this way, the tank 10 provides a health and safety advantage. The airline valve 26, once activated, is able to equalise the pressure between the first volume and exterior of the tank 10. The vent 34, provided on the second skin 13, may be opened to alleviate any pressure discrepancies between the void 52 and the exterior of the tank 10. 8 [0033] Further pressure discrepancies between the first volume and the atmosphere may be automatically alleviated through the relief valve 44. If an operator desired to manually activate the relief valve 44, this may be done by pulling on the handle 45. The position of the handle 45 also contributes to the healthy and safety advantage of the tank 10 by allowing manual operation of the relief valve 44 elsewhere than the top of the tank 10. Ideally, the handle 45 may be operated from or near ground level. [0034] Once the first volume of the tank 10 holds any amount of fluid, the level of said fluid may be displayed by the level gauge 42. The float 50 is in connection with the arm 54 which is in turn in connection with the level gauge 42. To read the level of fluid in the tank 10, the float 50 will, under the effects of buoyancy, sit near the top level of said fluid. The arm 54 will then display, at the level gauge 42, the volume of the fluid in the tank. The level gauge 42 may be seen and read by an operator though the sight glass. [0035] A traditional dipstick may also be used to ascertain the level of fluid within the tank 10. The access point 25 in the top dish 23 provides an opening for the dip stick to enter the tank 10. The plate 14 provided on the frame 12 may be used to display signage indicating the contents of the tank or any other information deemed necessary. [0036] Any unwanted fluid which may be present between the two walls of the skirt 19 will be prevented from being trapped. This is due to the presence of the holes 30 cut into the outer skin 13 between the outer wall of the skirt 19 and the void 52 allowing passage of said fluid, under gravity, to the void 52. The presence of this unwanted fluid, along with any unwanted fluid already present within the void 52, will be ascertainable by an operator through viewing the transparent tube of the contents indicator 46. [0037] Under the effects of gravity, any fluid within the void 52, including that drained through the holes 30, will move to the contents indicator 46. The transparent tube of said contents indicator 46 will display the presence of said fluid. Furthermore, due to the nature of liquid and fluids heavier than air, and their displacement of air, the vertical level of any liquid within the void 52 will be readable from the transparent tube of the contents 9 indicator 46. The drain 48 provided on the contents indicator 46 allows for the drainage and hence removal of fluid present within the void 52. [0038] The central cap 35 and outer flange 39 of the outlet assembly 36 enable said outlet assembly to fit to and seal with both the first skin 11 and the second skin 13, preferably with one or more gaskets 37 at the underside of the tank 10. Hence, the outlet assembly 36 may adequately seal both skins 11 and 13 of the tank 10 while provide access, when desired, to the interior of the tank. When part or all of the contents of the tank 10 are required to be removed, the lid 24 in the top dish 23, the outlet assembly 36 or the sample valve 38 may be utilised. [0039] The containment system comprising drip trays 40 act to ensure any fluid which escapes from the tank 10 is kept in the immediate area. The drip trays 40, in accordance with known methods, catch any escaped fluid from either or both of the outlet assembly 36, or central underside of the tank 10, and the sample valve 38 at the distal end of the outlet assembly 36. [0040] Modifications and variations as would be apparent to a skilled addressee are deemed to be within the scope of the present invention. 10

Claims (5)

1. A tank for storage of fluid comprising: a. a body having first and second skins; the first skin arranged to define a first volume for receiving and containing the fluid and the second skin defining a second volume for accommodating the first skin and first volume; wherein the first and second skins are spaced apart by a void; b. an outlet disposed at an underside of the body, for selective filling and drainage of the fluid; and c. an outlet assembly receivable by the outlet, wherein the outlet assembly seals with both skins.

2. A tank according to claim 1, further comprising an airline valve with an operating mechanism within reach of an operator on ground level.

3. A tank according to claim 1 or 2, further comprising a means for visual determination of the presence and level of contents in the void between the spaced apart first and second skins.

4. A tank according to any one of claims 1 to 3, further comprising level indicator including a float and gauge for assessment and display of the level of the contents of the first volume of the tank.

5. A tank according to any one of claims I to 4, provided within a frame comprising a deluge system for the control or suppression of a fire. 11