AU2015234358A1 - Relocatable tank wall system - Google Patents

Abstract

The present invention relates to a relocatable tank wall system and, in particular, to a tank wall system of the type configured to contain an internal liner carrying a volume of liquid. The tank wall system has at least a partial tube frame construction and does not include ground penetrating components and is thus capable of being assembled, disassembled, transported and re-assembled quickly and efficiently. The present invention may further relate to a tank incorporating the tank wall system, and a method of constructing the tank wall system. Cj %r 00) {0 t LO) u U,/ MD

Description

1 RELOCATABLE TANK WALL SYSTEM FIELD OF THE INVENTION [0001] The present invention relates to a relocatable tank wall system and, in particular, to a tank wall system of the type configured to contain an internal liner carrying a volume of liquid. The tank wall system has a tube frame construction and does not include ground penetrating components and is thus capable of being assembled, disassembled, transported and re-assembled quickly and efficiently. The present invention may further relate to a tank incorporating the tank wall system, and a method of constructing the tank wall system. BACKGROUND OF THE INVENTION [0002] There is currently a need, particularly in the Australian mining sector, for short term storage of large volumes of water. For example, it is not uncommon in oil/gas drilling operations in the Australian outback to consume in excess of a million litres of water over a 4-5 week period. These large volumes of water are held in large circular tanks (which can span over 40 metres in diameter, extend over 2 metres in height, and hold over 4000kL in volume), which typically comprise a tank wall system that acts as a liquid containment wall for an internal tank liner carrying the volume of water. The tank wall system acts against the hydrostatic loads of the liquid, and also protects against wind and other loads. [0003] A problem with existing tank wall systems known to the Applicant is that whilst they may be suitable for supporting liners holding such large volumes of water, they are not designed for short term use and it follows that tanks incorporating such wall systems are not capable of being quickly and easily disassembled and relocated. An example of where relocation of a tank may be desirable is where two mining sites or camps are positioned in close vicinity and where tanks that have been used (and no longer required) at one site are required at the other within a short timeframe. Another example may be where camps themselves relocate in order to continue operations at an adjacent location, for example, during the laying of pipeline across vast distances. In this scenario, there is a need for water tanks to be disassembled and relocated just as quickly if not quicker than the camp itself.

2 [00041 Even tanks that have been designed for short term use have their shortcomings. For example, most tank wall systems known to the Applicant are constructed using ground penetrating support components including, for example, in ground footings. This may be in the form of a single ballast or a plurality of ballasts typically made of concrete. Such ballasts may be spaced externally around the perimeter of the tank or extend around the perimeter. Non-external anchoring components include ground-penetrating piles, sometimes known as "duckbill" anchors, which may be spread around the perimeter and driven into the ground using a jack hammer or similar equipment. [0005] Notwithstanding the type of ground penetrating anchor that is used, preparing the ground beneath where such tanks are to be located and then preparing and/or erecting the anchors is an inefficient, time consuming and expensive task. For example, a plurality of holes or a single trench will often need to be dug where the tank is to be assembled to accommodate footing(s) formed by pouring concrete into the holes or trench. Other scenarios may require the entire area beneath the tank to be concreted. The skilled addressee would understand that any assembly process for tank wall systems involving the pouring of concrete below ground, or the hammering of anchors into the ground, will not result in a tank that is easily disassembled and relocated, and will not result in a worksite that is left in the state it was when the camp arrived. [0006] Problems have also arisen where the land that needs to be worked or excavated to accommodate such tanks is sacred indigenous land, and indeed legislation in countries such as Australia do not allow for the excavation of land beyond 300mm into the ground in protected areas without special permit. This also has the effect of increasing the expense and time required to assemble and disassemble some existing tanks in such areas. [0007] The construction of tanks, notwithstanding the existence or type of anchoring it utilises, is also a major factor in the tank's propensity to be able to handle large volumes and at the same time being capable of quick and easy assembly and disassembly. In particular, when known construction techniques are applied to large scale tanks, structural failure and water leakage have been known to result under certain hydrostatic and wind loads.

3 [0008] One construction method involves stacking large diameter circular ring sections of corrugated panel construction which define the perimeter of the tank. This particular construction method involves the abovementioned duckbill anchors. The individual corrugated panels are transported to the site location where each ring section is subsequently assembled using a plurality of the panels. The ring sections are approximately 1.1m high and are therefore constructed individually and then stacked and bolted on top of each other (panels of each ring bolt together, with bolts loaded in shear) to give the tank height. Such tanks typically include a single, continuous beam which extends around the perimeter of the uppermost ring section, known as a "wind ring", which stiffens the top edge of the ring section under compression. [0009] Another known technique involves the use of heavy steel plate sections which extend the full height of the tank and which are bolted together along their side edges to form a circular perimeter (with bolts loaded in tension). The plate sections are slightly curved so that when constructed the tank wall forms a circular structure. Tank walls constructed using this crude technique may have sufficient rigidity to support large hydrostatic forces, but do not lend themselves to quick and easy disassembly, relocation and assembly. For example, such steel panels require a mobile crane to assemble and disassemble the panels. [0010] A common theme across known tank wall construction of this type, including the examples provided above, is that they employ a monocoque-type construction (to use an automotive analogy). This means that it is the actual circular shape of the wall or "skin" of the tank which provides the structural support and supports most of the hydrostatic and wind loads. For reasons already mentioned above, there are problems with this construction approach particularly in tanks having a diameter exceeding 15-20 metres (which may support in excess of 500kL of water), and in excessive wind load areas. In addition, most tanks of this construction do not meet country-specific design requirements for wind loading such as Australian Standard AS1 170.2. These tank wall designs typically require in-ground anchors, a large number of fasteners, and heavy components, all of which are necessary to provide sufficient strength to the structure but which result in a tank that is not easily assembled, disassembled and/or transported. [0011] It is an object of the present invention to overcome at least some of the aforementioned problems or to provide the public with a useful alternative.

4 [0012] Any discussion of documents, acts, materials, devices, articles or the like, which has been included in the present specification is solely for the purpose of providing a context for the present invention. It should not be taken as an admission that any or all of the previous discussion forms part of the prior art base or was common general knowledge in the field of the invention as it existed before the priority date of any of the claims herein.

5 SUMMARY OF THE INVENTION [0013] In one aspect, the present invention provides a tank wall system for a tank of the type including an internal liner for holding liquid, the tank wall system including: a plurality of upstanding, substantially flat wall panels of at least a partial tube frame construction, wherein adjacent wall panels are configured to be fastened to one another along their side edges at an angle that results in the formation of an enclosed polygon tank wall shape having multiple sides defined by each of said plurality of flat wall panels. [0014] The skilled addressee would appreciate that a tank wall system having upstanding wall panels oriented to form a polygon shaped tank wall and being of a tube frame construction enables for the quick and easy assembly and disassembly of such components. Furthermore, because the panels are not curved and are of a tube frame construction, these components can be flat packed and transported with ease. [0015] In an embodiment, each flat wall panel includes a substantially rectangular frame including horizontal structural elements, and two vertical and spaced apart structural elements defining the side edges of the wall panel. [0016] In an embodiment, the vertical structural elements of each wall panel are configured to enable adjacent wall panels to be fastened to one another at said angle resulting in the formation of an enclosed polygon tank wall shape. [0017] In an embodiment, the vertical structural elements of each wall panel each include a web portion that does not extend perpendicularly to said horizontal structural elements but extends on an angle to ensure that when an outer face of the web portion abuts with an outer face of a vertical structural element of an adjacent panel, the panel and the adjacent panel extend at said angle resulting in the formation of an enclosed polygon tank wall shape. [0018] The skilled addressee would appreciate that starting with a freestanding leg panel and erecting an adjacent standard wall panel at a predefined angle and then repeating this process until the entire wall is constructed, and where the wall panel 6 frames are pre-configured for attachment at the predefined angle, assembly time is greatly reduced. [0019] In an embodiment, the abutting web portions are adapted to be connected using fasteners extending through the web portions and thereby loaded in shear, wherein the web portion of each abutting vertical structural element is sufficiently thick to withstand imposed connection loads including tension and/or moment loads. [0020] In an embodiment, the web portion is sufficiently wide to accommodate at least one vertically extending row of fasteners. [0021] In an embodiment, said web portion accommodates two vertically extending rows of fasteners. [0022] In an embodiment, the fasteners are nut and bolt fasteners. [0023] In an embodiment, the horizontal structural elements include two horizontal and spaced apart structural elements defining an uppermost and lowermost edge of the wall panel. [0024] In an embodiment, each panel includes a base plate associated with each lower corner of the panel, each base plate thereby disposed beneath fastened horizontal structural elements and ends of lowermost horizontal structural elements of two adjacent wall panels. [0025] In an embodiment, the horizontal structural elements include a plurality of internal, spaced apart cross beams extending horizontally there between. [0026] In an embodiment, one or more of the wall panel structural elements, including the internal cross beams, provide a substantially flush internal surface for accommodating internal cladding. [0027] In an embodiment, the internal cladding is in the form of plywood panels.

7 [0028] In an embodiment, the vertical structural elements defining the side edges of the wall panel, and the horizontal structural elements defining the uppermost and lowermost edges of the wall panel, are each internally directed C-section beams. [0029] In an embodiment, the vertical structural elements defining the uppermost and lowermost edges of the wall panel are flat sections, and the uppermost horizontal structural element is a downwardly directed C-section beam extending there between. [0030] In an embodiment, an outer flange of the downwardly extending C-section beam includes at least one liner clamp adapted to clamp liquid holding liner to a top portion of each wall panel. [0031] In an embodiment, the lowermost horizontal structural element is an L shaped beam extending between the vertical structural elements, wherein a lower flange portion of the L-shaped beam is configured to line a ground surface upon which the wall panel is supported. [0032] In an embodiment, the tank wall system further includes a plurality of externally positioned, above-ground ballast blocks. [0033] In an embodiment, the ballast blocks are spaced around an external perimeter of the tank wall system and each ballast block is joined to the uppermost edge of a wall panel by a ballast brace extending between the downwardly directed C section beam to an upper portion of the ballast block under tension. [0034] In an embodiment, each ballast block is constructed of concrete. [0035] In an embodiment, each wall panel further includes external cladding in the form of corrugated sheeting. [0036] In an embodiment, at least some of the flat wall panels are leg panels which include an above-ground footing system at a base of the panel. [0037] In an embodiment, the wall panels which are not leg panels are standard wall panels without said footing system.

8 [0038] In an embodiment, the tank wall system includes alternating standard and leg panels around a perimeter of the tank wall system. [0039] In an embodiment, the footing system of each panel includes at least one internal stabiliser beam which extends along a ground surface inwardly from the wall panel in a direction towards a centre of the tank structure to thereby stabilise the wall panel in said upstanding position. [0040] In an embodiment, the footing system further includes a stabiliser plate associated with each internal stabiliser beam at or adjacent an internal end thereof. [0041] In an embodiment, the footing system further includes a base plate associated with each lower corner of the leg panel, each base plate disposed beneath a horizontal structural member extending outwardly from the wall panel and configured to accommodate an internal stabiliser beam. [0042] In an embodiment, the footing system components are linked by the structural element forming the lowermost edge of the panel. [0043] In an embodiment, each flat wall panel further includes an external stabilising beam extending along the ground surface between adjacent stabilising structural members, said external stabilising beam extending a spaced distance from and substantially parallel to the flat wall panel frame. [0044] In an embodiment, the ballast blocks are spaced around the external perimeter of the tank wall system and coupled to the wall panels via perimeter beams associated with an upper edge of the wall panels. [0045] In an embodiment, a single perimeter beam spans a distance between the external ballast locations. [0046] In an embodiment, a plurality of perimeter beams span the distance between the external ballast locations whereby each wall panel includes a corresponding perimeter beam.

9 [0047] In an embodiment a plurality of perimeter beams span the distance between the external ballast locations whereby every two or more wall panels includes a corresponding perimeter beam. [0048] In an embodiment, the perimeter beams extend across the top and between upper corners of the wall panels. [0049] In an embodiment, each perimeter beam includes a narrow, rectangular frame adapted to be fastened to the uppermost horizontal structural elements of the wall panel(s). [0050] In an embodiment, the ends of each perimeter beam, or fastening components associated therewith, are configured to enable adjacent perimeter beams to be fastened to one another at an angle of orientation dependent upon the angle of orientation of adjacent wall panels. [0051] In an embodiment, for a tank wall system with thirty-six wall panels having an angle of rotation between adjacent wall panels of approximately 10 degrees, eighteen perimeter beams each spanning two adjacent wall panels have an angle of rotation between adjacent perimeter beams of approximately 20 degrees. [0052] In an embodiment, a ballast bracket is supported at a junction between two adjacent perimeter beams and the ballast bracket extends in a direction outwardly from the wall panel, a ballast brace extending from the outwardly extending portion of the ballast bracket to an upper portion of the ballast block under tension. [0053] In another aspect, the present invention provides a tank including a tank wall system as characterised in any one of paragraphs [0013] to [0052]. [0054] In an embodiment, the tank wall system thirty-six wall panels having an angle of rotation between adjacent wall panels of approximately 10 degrees. [0055] In an embodiment, the tank further includes an internal liner adapted to carry a volume of liquid contained within the tank wall system.

10 [0056] In an embodiment, the tank further includes a plurality of internal ballast blocks spaced along a ground surface inside the tank wall system and configured to cause separation between the internal liner and the ground surface. [0057] In yet another aspect, the present invention provides a method of constructing a tank wall system including: erecting a first, flat wall panel of at least partial tube frame construction such that said first wall panel is upstanding; erecting a second wall panel of flat and at least partial tube frame construction such that the second wall panel is upstanding adjacent said first wall panel, the second wall panel being of a corresponding size and shape to said first wall panel; fastening the second wall panel to the first wall panel along a side edge of each wall panel; and repeating said erecting and fastening steps for subsequent wall panels until a full perimeter of the tank wall system is formed, wherein adjacent wall panels are configured to be fastened to one another along their side edges at an angle that results in the formation of an enclosed polygon tank wall shape having multiple sides defined by each of said plurality of flat wall panels. [0058] In an embodiment, each wall panel side edge includes a web portion that extends at an angle that ensures that when an outer face of the web portion abuts with an outer face of a side edge associated with an adjacent panel, the panel and the adjacent panel extend at said angle resulting in the formation of an enclosed polygon tank wall shape. [0059] In an embodiment, the method further includes: anchoring the tank wall system using a plurality of above-ground ballast blocks positioned around said perimeter. [0060] In an embodiment, the method further includes: strengthening the wall panels using a plurality of adjoining perimeter beams spanning one or more wall panels, wherein each perimeter beam is fastened to upper structural elements of the spanned wall panels. [0061] In an embodiment, the method further includes: 11 anchoring the perimeter beams using a plurality of above-ground ballast blocks positioned around said perimeter. [0062] In a further aspect, the present invention provides a tank wall system constructed using a method according to any one of paragraphs [0057] to [0061].

12 BRIEF DESCRIPTION OF THE FIGURES [0063] Features of the present disclosure are illustrated by way of example and not limited in the following figure(s), in which like numerals indicate like elements, in which: Figure 1 is a perspective view of a tank wall system according to an embodiment of the present invention; Figure 2 is an enlarged perspective view of a portion of the tank wall system of Figure 1; Figure 3 is a perspective view of a single, leg wall panel erected according to an embodiment; Figure 4 is a perspective view of a leg wall panel and standard wall panel fastened along a side edge thereof at an angle to form an angled wall panel pair according to an embodiment; Figure 5 is a top view of a standard wall panel according to an embodiment and an enlarged view of its side edge construction; Figure 6 is an enlarged perspective view of plurality of alternating leg and standard wall panels fastened along side edges at an angle to form a full perimeter of angled wall panel pairs according to an embodiment; Figures 7-8 are perspective views demonstrating the installation of perimeter beams to wall panels according to an embodiment; Figure 9 is an enlarged perspective view of tank wall system panels, one of which includes an equalizing nozzle location according to an embodiment; Figure 10 is an enlarged perspective view of tank wall system panels including a ballast block and external cladding installed according to an embodiment; Figure 11 is a perspective view of a tank wall system according to another embodiment of the present invention, including three enlarged perspective views of portions of the tank wall system; 13 Figure 12 is an enlarged underside perspective view of a further portion of the tank wall system of Figure 11; Figure 13 is an enlarged perspective view of a further portion of the tank wall system of Figure 11; Figure 14 is a top view spanning three wall panels of the tank wall system of Figure 11; and Figure 15 is an enlarged top view of a join between adjacent wall panels of the tank wall system of Figure 11.

14 DETAILED DESCRIPTION OF THE EMBODIMENT(S) OF THE INVENTION [0064] For simplicity and illustrative purposes, the present disclosure is described by referring mainly to an example thereof. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present disclosure. It will be readily apparent however, that the present disclosure may be practiced without limitation to these specific details. In other instances, some methods and structures have not been described in detail so as not to unnecessarily obscure the present disclosure. As used herein, the terms "a" and "an" are intended to denote at least one of a particular element, the term "includes" means includes but not limited to, the term "including" means including but not limited to, and the term "based on" means based at least in part on. [0065] The present invention according to an aspect relates to a tank wall system 10 of the type used to contain an internal liner (not shown) which carries liquid, the tank wall system 10 including a plurality of upstanding, substantially flat wall panels 12 of at least partial tube frame construction. This tank construction differs from that which is used in existing tank wall systems known to the Applicant which employ a monocoque type construction. In the tank wall system 10 shown, adjacent wall panels 14 and 16 may be fastened to one another along their side edges at an angle that results in the formation of an enclosed polygon wall shape having multiple sides defined by each of the plurality of flat wall panels 12. The polygon shape of the tank and in particular the flat panel construction allows for each component of the tank to be easily assembled, disassembled and packed ready for transportation. [0066] Figure 1 illustrates a tank wall system 10 according to an embodiment of the present invention and Figure 2 illustrates an enlarged view of a portion of the tank wall system 10. The present invention further provides a tank incorporating the tank wall system 10 and may include additional components including a tank liner (not shown) contained inside the tank wall system for holding liquid and a plurality of internal ballast blocks 18 used to separate the tank liner from a ground surface. The tank wall system as shown in Figure 1 is ready to receive the tank liner which may then be filled via an equalizing nozzle assembly 20 (shown in more detail in Figure 9) accessible from an exterior of the tank wall system as described in more detail below. Indeed, each 15 component of this exemplified tank wall system 10 and a method of assembling same according to an embodiment will now be described in more detail. [0067] Each flat wall panel 12 may be a "leg panel" 14 which includes components forming part of an above-ground footing system, described further below, to enable the panel to be freestanding or a "standard panel" 16 which does not include all of the base stabilising components. For the purpose of brevity, like features between panels 14 and 16 are referred to herein using like descriptors and reference numerals. An assembler of the system 10 may start with a single leg panel 14 as shown in Figure 3. Each panel 12 includes a substantially rectangular frame including two vertical and spaced apart structural elements 22 and 24 defining the side edges of the wall panel, and two horizontal and spaced apart structural elements 26 and 28 defining an upper and lower (which may be an uppermost and lowermost) edge of the wall panel. The structural elements 22, 24, 26 and 28 may be internally directed C-section beams, although other structural configurations are possible. For example Figure 3 shows that whilst the vertical elements 22 and 24 are C-section beams, the uppermost and lowermost beams 26 and 28 are not. Not all shapes and configurations of all beams depicted in the drawings will be described herein. [0068] The vertical structural elements 22 and 24 may include a plurality of internal, spaced apart cross beams 30 extending horizontally between the vertical structural elements 22 and 24. Further, the wall panel structural elements 22 and 24 including the internal cross beams 30 may provide a substantially flush internal surface for accommodating internal cladding which may be constructed of any appropriate material. For example, the internal cladding in the embodiment shown is in the form of plywood sheeting 32. Any one panel 12 may also include diagonal bracing 33 as shown in the leg panel 14 shown in Figure 1. [0069] Each leg wall panel may include stabilising horizontal structural members 34 at each lower corner of the leg panel 14 which extend outwardly and externally a short distance from the wall panel. The stabilising structural member 34 may be hollow to telescopically accommodate an internal stabiliser beam 36 which extends along the ground surface inwardly and internally from the wall panel 14 a sufficient distance to stabilise the leg wall panel 14 in an upstanding or upright position. In addition, the structural element 34 may be supported above a base plate 37, and each internal 16 stabiliser beam 36 may include a stabiliser plate 38 at or adjacent an internal end thereof to increase the contact area with the ground surface. Additional features of each panel 12 will be described below. [0070] Turning to Figure 4, it is apparent that each of the leg 14 and standard 16 panels are configured to be joined or fastened together along an available side edge thereof to form a panel pair. In the embodiment shown, the vertical structural element 26 of panel 14 is configured for fastening to element 24 of panel 16. The tank wall system 10 may be made up of a plurality of such panel pairs including alternating standard and leg panels 14 and 16 around the perimeter of the tank wall system 10, although the invention is not intended to be limited to using alternating panel types. For example, all or most panels could be constructed to be of the freestanding leg panel type 14, and likewise all or most panels could be constructed to be of the standard panel type 16. [0071] In an embodiment, each flat wall panel further includes an external stabilising beam 40 extending along the ground surface between adjacent stabilising structural members, said external stabilising beam extending a spaced distance from and substantially parallel to the flat wall panel frame. This beam 40 together with internal stabilising beams 36 allow panel 14 to be freestanding and increase the general stability of the structure. Flanges 42 associated with ends of each structural member 34 may be used to allow for fastening of the beams 40. The lowermost edge beam 28 and external stabilising beam 40 may each be an L-section beam whose horizontal component abuts with the ground surface. [0072] When considering the tank wall structure as a whole, the components which may be said to form part of the "above-ground footing system" include the base and stabiliser plates 37 and 38 respectively, and the stabiliser beam 36. These may be linked together by the lowermost edge beam 28, and their purpose is to add to the stability of the structure and create a mechanism to transfer the loads into the foundation which in this case is the ground surface. [0073] The skilled addressee would understand that in order for erected panel pairs to meet again at the first pair, the number and angle of orientation of adjacent panels needs to be pre-calculated. In the embodiment shown in Figure 1 for example, there are 17 thirty-six panels 12 having an angle of rotation between each panel of approximately 10 degrees. However, it is to be understood that variations are possible depending on the required size of the tank. As shown in Figure 5, the side structural elements 22 and 24 may be manufactured such that they are angled according to the required angle of rotation of the panels 12 to ensure that they provide an abutment surface with the structural element of an adjacent panel, and so on. [0074] In the embodiment shown, the horizontal beams 26, 28 and 30 include ends 44 that are shaved at the appropriate angle to provide a flush and appropriately angled surface along the height of the horizontal beams to which the vertical 22 or 24 may be fastened. This also ensures that bolts 45 used to fasten two adjacent panels can be bolts loaded in tension rather than in shear. The configuration of the vertical structural elements 22 and 24 as shown in Figure 5 and the means of fastening the elements is not described further in view of the multiple different ways that fastening could be achieved, including fastening of the cross beams 30 between the vertical elements. [0075] The skilled addressee would appreciate that starting with a freestanding leg panel 14 and erecting an adjacent standard wall panel 16 at a predefined angle and then repeating this process until the entire wall is constructed, assembly time is greatly reduced. Multiple panel pairs that have been joined by means described above are shown in Figure 6. [0076] The tank wall system 10 may further include a plurality of perimeter beams 46 which are shown to span at least two adjacent flat wall panel pairs. When spanning over two panels 14 and 16, as shown in Figure 8 for example, each perimeter beam 46 forms a substantially triangular structure between the perimeter beam 46 and adjacent wall panels 14 and 16. The perimeter beam 46 may alternatively span over one panel (provided the structural detail was sufficient) or more than two panels. The use of perimeter beams differs to prior art tank wall systems in which a single continuous beam often supports an entire tank wall. The purpose of the perimeter beams is described in more detail below. [0077] Figures 7 and 8 illustrate a means by which the beams may be attached according to an embodiment. Each perimeter beam may include a narrow, rectangular frame adapted to be fastened to the uppermost horizontal structural elements 26 of 18 each corresponding adjacent wall panel pair. Perimeter beam bolt fasteners 48 may be installed in the top structural element 26 of each panel, as shown in Figure 7, which may then accommodate the perimeter beam 46 there above, as shown in Figure 8. Each perimeter beam 46 may extends across the top of the wall panels and spans two adjacent, angled wall panels. However, it is to be understood that other perimeter beam fastening options are available. In addition, the perimeter beam need not necessarily have a rectangular frame structure as shown and could for example include a curved structure. [0078] As with the wall panels, the ends of each perimeter beam 46 may be configured to enable adjacent perimeter beams to be fastened to one another using bolts loaded in tension. In this regard, each perimeter beam 46 may include at least one structural surface at an end thereof that is also angled to ensure that the perimeter beam angled surface abuts with the same angled surface of an adjacent perimeter beam 46. When spanning two wall panels, the skilled person would understand that adjacent perimeter beams are angled at approximately double the angle of adjacent wall panels. For example, for a tank wall system with thirty-six wall panels having an angle between adjacent wall panels of approximately 10 degrees, there may be eighteen perimeter beams each separated by an angle of approximately 20 degrees. [0079] As mentioned earlier, the tank wall system 10 may include an equalizing nozzle assembly 20 and the configuration and placement of same, according to an embodiment, is shown in Figure 9. The skilled addressee would know that such a nozzle assembly is used to fill the tank liner with liquid and is configured for attachment to known hose attachments which transport liquid to the tank. In the embodiment shown, the nozzle assembly forms part of a cross beam 30. [0080] The tank wall system may further include a plurality of external, above ground ballast blocks 50. The skilled addressee would appreciate that the above-ground ballast blocks 50 combined with other structural aspects allows for the tank wall system to be assembled without penetrating a ground surface which would otherwise be the case in tank wall systems requiring in-ground anchors. [0081] The ballast blocks may be spaced around the external perimeter of the tank wall system, as shown by way of example in Figure 1, and coupled to the perimeter 19 beams via a ballast brace 52 as shown in enlarged view in Figure 10. A ballast bracket 54 may be supported at a junction between two adjacent perimeter beams 46 and the ballast bracket 54 may extend in a direction outwardly and downwardly from the wall panel as shown, the ballast brace extending from the outwardly extending portion of the ballast bracket 54 to an upper portion of the ballast block 50 under tension. The ballast block may be constructed of concrete. In the example of Figure 1 which is a thirty-six panel tank wall system, a ballast block 50 is present at every sixth wall panel 12 (or every three perimeter beams 46). The skilled addressee would understand that the connection between the wall panels create a hinge at the panel connections disposed between external ballast locations. The perimeter beams 46 create the ability to carry a bending moment across the span between the external ballast locations. This is distinct from the continuous beams used in the prior art to provide stiffness to the open edge to stop the circular vessel from buckling. In an embodiment, each perimeter beam could be made to span between external ballast locations and still provide the required capacity. [0082] The tank wall system 10 may further include external cladding upright supports 56 at the junction between adjacent wall panels 12, wherein adjacent supports 56 provide a substantially flush external surface for accommodating external cladding sheets 58. The side structural elements may include outwardly extending brackets 60 for accommodating such supports 56, and the external cladding sheets may be in the form of corrugated iron sheets as shown by way of example in Figure 10. [0083] Figure 11 illustrates a tank wall system 70 according to another embodiment of the invention, and Figures 11 to 15 illustrate enlarged views of various portions of the tank wall system 70. The present invention further provides a tank incorporating the tank wall system 70 and may include additional components including a tank liner (not shown) contained inside the tank wall system 70 for holding liquid and a plurality of internal ballast blocks (not shown in Figure 11 but described with respect to the earlier embodiment) used to separate the tank liner from a ground surface. The tank wall system as shown in Figure 11 is ready to receive the tank liner which may then be filled via an equalizing nozzle assembly (not shown in Figure 11 but described with respect to the earlier embodiment) accessible from an exterior of the tank wall system.

20 [0084] The skilled addressee will appreciate that the tank wall system 70 resembles the tank wall system 10 of the earlier embodiment in that it too includes a plurality of upstanding, substantially flat wall panels 72 of at least partial tube frame construction forming an enclosed polygon tank wall shape having multiple sides defined by each of the plurality of flat wall panels 72, but with various differences which will become apparent. [0085] Each flat wall panel 72 of the tank wall system 70 includes adjacent wall panels 74 and 76 which are substantially identical wall panels. Each panel 72 includes a substantially rectangular frame including two vertical and spaced apart structural elements 78 and 80 defining the side edges of the wall panel, and two horizontal and spaced apart structural elements 82 and 84 defining an upper and lower (which may be an uppermost and lowermost) edge of the wall panel. [0086] The tank wall system 10 of the earlier embodiment included vertical structural elements in the form of internally directed C-section beams. In contrast, the tank wall system 70 includes vertical structural elements 78 and 80 in the form of flat sections. These flat sections are configured to allow space for more fasteners, and for improved access to the fasteners from an exterior of the tank when connecting or disconnecting adjacent wall panels 74 and 76. In the embodiment shown, the fasteners are a double row of bolts (and associated nuts) 85 as shown most clearly in Figure 12. The vertical structural elements 78 and 80 are of a thick construction in order to withstand the imposed connection loads (tension and moment). In an embodiment, the thickness of these sections 78 and 80 is 16mm, however, other thicknesses may be suitable depending on the size of the tank. [0087] The reader will appreciate that horizontal flat beams 26 and the perimeter beams 46 at the top of each wall panel 12 in the earlier described embodiment are replaced with a single, downwardly facing C-section beam 82 integrated into the wall panel 72 of the tank wall system 70. Additionally, the lower structural element 84 of the wall panel 72 is in the form of a single L-shaped beam extending between the vertical structural elements 78 and 80, as shown most clearly in Figure 13. This beam 84 may be supported at each of its ends above a base plate 86 to which a base portion of the L shaped beam 84 may also be bolted using bolts (and associated nuts) 87.

21 [0088] The skilled addressee would realise that the use of the top C-section beam 82 integrated into the wall panel frame and a double row of bolts (and associated nuts) 85 at each panel join in the tank wall system 70 effectively replaces the perimeter beam 46 and the various base stabilising components of the tank wall system 10. The double row of bolts (and associated nuts) 85 provides the tank wall system 70 with the ability to resist moments created by external, non-axisymmetric loads (e.g. wind loads). Accordingly, the perimeter beam 46 and various base stabilising components described with respect to the tank wall system 10 are no longer required to resist the expected service loads. [0089] The vertical structural elements 78 and 80 may include a plurality of internal, spaced apart cross beams 88 extending horizontally between the vertical structural elements 78 and 80. Further, the wall panel structural elements 74 and 76 including the internal cross beams 88 may provide a substantially flush internal surface for accommodating internal cladding which may be constructed of any appropriate material. For example, the internal cladding in the embodiment shown is in the form of plywood sheeting 90 as shown and described in the earlier embodiment. Any one panel 72 may also include diagonal bracing 92, and a plurality of external, above-ground ballast blocks 94 coupled to the upper beams 82 via a ballast brace 96, these and their associated features also described earlier with respect to tank wall system 10. In the example of Figure 11 which is a thirty-six panel tank wall system, a ballast block 94 is present at every fourth wall panel 72. [0090] As shown in Figures 14 and 15, the side structural elements 78 and 80 may be configured such that they are angled according to the required angle of rotation of the panels 72 to ensure that they provide an abutment surface with the structural element of an adjacent panel. [0091] As per the previous embodiment, the horizontal beams 82, 84 and 88 may include ends 98 that are shaved at an angle to provide a flush and appropriately angled surface along the height of the horizontal beams to which the vertical structural elements 78 and 80 may be fastened (for example, welded to the shaved ends of the horizontal beams 82, 84 and 88). This also ensures that bolts (and associated nuts) 85 used to fasten two adjacent panels can be loaded in tension rather than in shear.

22 [0092] The skilled addressee would appreciate that starting with a panel 74 and then erecting an adjacent panel 76 at a predefined angle, and then repeating this process until the entire wall is constructed, the tank assembly time is greatly reduced. Multiple panel pairs that have been joined by means described above are shown in Figures 11 to 15. [0093] The tank wall system 70 may further include external cladding 100 which may be screwed directly to the vertical structural elements 78. Also shown in Figures 11 and 12 in particular are liner clamp grips 102 used to secure liner (which may be in the form of geombrane) to the tank structure, in particular, to clamp the liner to the outer flange of the upper C-section beam 82. These clamps 102 may be bolted 104 directly to this outer flange portion of the upper beam 82. [0094] The tank wall systems 10 and 70 as described above according to various embodiments provide a number of advantages over traditional tank wall systems of this type, including but not limited to: * a light-weight, low profile structure with no single component needing to exceed 400kg, without compromising strength, stability, and necessary support against hydrostatic and wind loads; * easily manufactured and transported (no low loader or over-width permits required) as each component is easily disassembled and flat packed; and * quick, efficient and safer assembly due to no ground-penetrating components, less fasteners, ability to access fasteners externally (from outside the tank), and overall improved polygon structure. [0095] What has been described and illustrated herein are examples of the disclosure along with some variations. The terms, descriptions and figures used herein are set forth by way of illustration only and are not meant as limitations. Many variations are possible within the scope of the disclosure, which is intended to be defined by the following claims -- and their equivalents -- in which all terms are meant in their broadest reasonable sense unless otherwise indicated. [0096] Throughout this specification and claims which follow, unless the context requires otherwise, the word "comprise", and variations such as "comprises" and 23 "comprising", will be understood to imply the inclusion of a stated integer or step, or group of integers or steps, but not the exclusion of any other integer or step, or group of integers or steps. [0097] The reference to any prior art in this specification is not, and should not be taken as, an acknowledgement or any suggestion that the prior art forms part of the common general knowledge.

Claims (29)

1. A tank wall system for a tank of the type including an internal liner for holding liquid, the tank wall system including: a plurality of upstanding, substantially flat wall panels of at least a partial tube frame construction, wherein adjacent wall panels are configured to be fastened to one another along their side edges at an angle that results in the formation of an enclosed polygon tank wall shape having multiple sides defined by each of said plurality of flat wall panels.

2. A tank wall system according to claim 1, wherein each flat wall panel includes a substantially rectangular frame including horizontal structural elements, and two vertical and spaced apart structural elements defining the side edges of the wall panel.

3. A tank wall system according to claim 2, wherein the vertical structural elements of each wall panel are configured to enable adjacent wall panels to be fastened to one another at said angle resulting in the formation of an enclosed polygon tank wall shape.

4. A tank wall system according to claim 3, wherein the vertical structural elements of each wall panel each include a web portion that does not extend perpendicularly to said horizontal structural elements but extends on an angle to ensure that when an outer face of the web portion abuts with an outer face of a vertical structural element of an adjacent panel, the panel and the adjacent panel extend at said angle resulting in the formation of an enclosed polygon tank wall shape.

5. A tank wall system according to claim 4, wherein the abutting web portions are adapted to be connected using fasteners extending through the web portions and thereby loaded in shear, wherein the web portion of each abutting vertical structural element is sufficiently thick to withstand imposed connection loads including tension and/or moment loads.

6. A tank wall system according to claim 5, wherein the web portion is sufficiently wide to accommodate at least one vertically extending row of fasteners.

7. A tank wall system according to claim 6, wherein said web portion accommodates two vertically extending rows of fasteners. 25

8. A tank wall system according to either claim 6 or claim 7, wherein the fasteners are nut and bolt fasteners.

9. A tank wall system according to any one of claims 2 to 8, wherein the horizontal structural elements include two horizontal and spaced apart structural elements defining an uppermost and lowermost edge of the wall panel.

10. A tank wall system according to claim 9, wherein each panel includes a base plate associated with each lower corner of the panel, each base plate thereby disposed beneath fastened horizontal structural elements and ends of lowermost horizontal structural elements of two adjacent wall panels.

11. A tank wall system according to any one of claims 2 to 10, wherein the horizontal structural elements include a plurality of internal, spaced apart cross beams extending horizontally there between.

12. A tank wall system according to claim 11, wherein one or more of the wall panel structural elements, including the internal cross beams, provide a substantially flush internal surface for accommodating internal cladding.

13. A tank wall system according to claim 12, wherein the internal cladding is in the form of plywood panels.

14. A tank wall system according to any one of claims 9 to 13, wherein the vertical structural elements defining the side edges of the wall panel, and the horizontal structural elements defining the uppermost and lowermost edges of the wall panel, are each internally directed C-section beams.

15. A tank wall system according to any one of claims 9 to 13, wherein the vertical structural elements defining the uppermost and lowermost edges of the wall panel are flat sections, and the uppermost horizontal structural element is a downwardly directed C-section beam extending there between.

16. A tank wall system according to claim 15, wherein an outer flange of the downwardly extending C-section beam includes at least one liner clamp adapted to clamp liquid holding liner to a top portion of each wall panel. 26

17. A tank wall system according to either claim 15 or claim 16, wherein the lowermost horizontal structural element is an L-shaped beam extending between the vertical structural elements, wherein a lower flange portion of the L-shaped beam is configured to line a ground surface upon which the wall panel is supported.

18. A tank wall system according to any one of claims 15 to 17, further including a plurality of externally positioned, above-ground ballast blocks.

19. A tank wall system according to claim 18, wherein the ballast blocks are spaced around an external perimeter of the tank wall system and each ballast block is joined to the uppermost edge of a wall panel by a ballast brace extending between the downwardly directed C-section beam to an upper portion of the ballast block under tension.

20. A tank wall system according to either claim 18 or claim 19, wherein each ballast block is constructed of concrete.

21. A tank wall system according to any one of the preceding claims, wherein each wall panel further includes external cladding in the form of corrugated sheeting.

22. A tank including a tank wall system according to any one of the preceding claims.

23. A tank according to claim 22, wherein the tank wall system thirty-six wall panels having an angle of rotation between adjacent wall panels of approximately 10 degrees.

24. A tank according to either claim 22 or claim 23, further including an internal liner adapted to carry a volume of liquid contained within the tank wall system.

25. A tank according to any one of claims 22 to 24, further including a plurality of internal ballast blocks spaced along a ground surface inside the tank wall system and configured to cause separation between the internal liner and the ground surface.

26. A method of constructing a tank wall system, including: erecting a first, flat wall panel of at least partial tube frame construction such that said first wall panel is upstanding; 27 erecting a second wall panel of flat, at least partial tube frame construction such that the second wall panel is upstanding adjacent said first wall panel, the second wall panel being of a corresponding size and shape to said first wall panel; fastening the second wall panel to the first wall panel along a side edge of each wall panel; and repeating said erecting and fastening steps for subsequent wall panels until a full perimeter of the tank wall system is formed, wherein adjacent wall panels are configured to be fastened to one another along their side edges at an angle that results in the formation of an enclosed polygon tank wall shape having multiple sides defined by each of said plurality of flat wall panels.

27. A method according to claim 26, wherein each wall panel side edge includes a web portion that extends at an angle that ensures that when an outer face of the web portion abuts with an outer face of a side edge associated with an adjacent panel, the panel and the adjacent panel extend at said angle resulting in the formation of an enclosed polygon tank wall shape.

28. A method according to either claim 26 or claim 27, further including: anchoring the tank wall system using a plurality of above-ground ballast blocks positioned around said perimeter.

29. A tank wall system constructed using a method according to any one of claims 26 to 28.