CA2767354C - Modular liquid storage tanks - Google Patents

Abstract

A modular liquid storage tank comprises a plurality of panels and a plurality of connection brackets for coupling adjacent pairs of panels together. The plurality of panels are arranged in a lateral edge-adjacent fashion, and each panel comprises a pair of opposed generally vertical sides, each having one or more protrusions adjacent thereto extending outwardly from the panel. The protrusions define opposed bearing surfaces which extend, in aggregate, along at least 10% of a length of the generally vertical sides. Each connection bracket comprises a pair of connection bars held in fixed relation to one another and separated by a distance approximately equal to the spacing between the opposed bearing surfaces of protrusions of an adjacent pair of panels such that each connection bracket is operable to laterally confine the protrusions of the adjacent pair of panels.

Description

MODULAR LIQUID STORAGE TANKS
Technical Field [0001] This invention relates to the field of modular tanks for storing large volumes of fluids.
Background

[0002] Modular tanks for storing of large volumes of fluids (e.g., water) may be useful in a variety of situations. For example, such tanks may find application in the extraction of subterranean hydrocarbons using hydraulic fracturing. Hydraulic fracturing requires large amounts of water. To store water necessary for hydraulic fracturing it is common to construct large, temporary water storage tanks (e.g., capable of storing more than 4 million gallons of water). Because such tanks are too large to be transported, modular tank designs comprising panels coupled together to form tank walls are often used in these applications.

[00031 The design of couplings for joining panels of modular tanks presents many challenges. Couplings must be strong enough to resist the large lateral loads exerted by water stored in tanks. Couplings should also be simple, so that tanks may be assembled and disassembled quickly by unskilled persons under challenging conditions (e.g., darkness, cold, etc.). Couplings should also be robust, so that they remain in serviceable condition over many assembly and disassembly operations.

[0004] Examples of prior art liquid holding tanks include:
= US Patent No. 6282863 = US Patent No. 4989751 US Patent No. 4267676 = US Patent No. 2863683 = US Patent No. 0700704 = US Patent No. 2378159 = US Patent No. 3280408 US Patent No. 5029426 = US Patent No. 5387049 = US Patent Application No. 20040103472 = US Patent No. 5592702 = US Patent No. 5083327 US Patent No. 2378128 = US Patent No. 4075801 = US Patent No. 1826918 = GB Patent No. 2408997 US Patent No. 5921049 = US Patent No. 4661008 = US Patent No. 4901497 = US Patent No. 3469865 US Patent No. 1060367 = US Patent Application No. 20110194893 [0005] The inventor has determined a need for improved modular liquid storage tanks, and in particular for such tanks having couplings permitting the tanks to be assembled with a minimum of time, expense and equipment (e.g., bracing, cranes, etc.).

Summary [0006] One aspect provides a modular liquid storage tank comprising a plurality of panels and a plurality of connection brackets for coupling adjacent pairs of panels together. The plurality of panels are arranged in a lateral edge-adjacent fashion, and each panel comprises a pair of opposed generally vertical sides, each having one or more protrusions adjacent thereto extending outwardly from the panel. The protrusions define opposed bearing surfaces which extend, in aggregate, along at least 10% of a length of the generally vertical sides.
Each connection bracket comprises a pair of connection bars held in fixed relation to one another and separated by a distance approximately equal to the spacing between the opposed bearing surfaces of protrusions of an adjacent pair of panels such that each connection bracket is operable to laterally confine the protrusions of the adjacent pair of panels.

[0007] In some embodiments, the pair of connection bars are held in fixed relation to one another by an elongate plate, and the connection bars extend inwardly from the plate along opposed longitudinal edges of the plate.

[0008] In some embodiments, the pair of connection bars are held in fixed relation to one another by a plurality of rungs, each rung being attached to both connection bars.
[0009] In some embodiments, the panels are arcuate and the tank is cylindrical with a generally circular cross section.

[0010] In some embodiments, the panels are straight and the tank is generally in the shape of a regular polygon.

= -3-[0011] In some embodiments, two or two or more panels are arcuate, two or more panels are straight, and the panels are arranged in a configuration such that additional straight panels may be added to increase the volume of the tank.

[0012] In some embodiments, the one or more protrusions comprise a panel bar extending outwardly from the panel along substantially an entire length of each of the generally vertical sides.

[0013] In some embodiments, the one or more protrusions comprise a plurality of panel bar sections extending outwardly from the panel spaced apart along each of the generally vertical sides.

[0014] In some embodiments, the panel bars or panel bar sections are generally rectangular;
and the connection bars are generally rectangular.
[0015] In some embodiments, the panel bars or panel bar sections have beveled outward lateral edges, and the connection bars have beveled inward lateral edges.

[0016] In some embodiments, the connection bars of a connection bracket define one or more sets of aligned apertures, and the one or more protrusions on adjacent edges of adjacent panels define one or more sets of corresponding aligned apertures. In addition, a plurality of retaining elements are provided, insertable through the aligned apertures of the connection bars and the protrusions on adjacent edges of adjacent panels to hold the connection bracket in place.
[0017] In some embodiments, each of the retaining elements comprises a rod.

[0018] In some embodiments, the rod has a hole through each end which is configured to receive a cotter pin.
[0019] In some embodiments, each of the retaining elements comprises a bolt, and one or more of the aligned apertures are threaded to receive the bolt.

[0020] In some embodiments, the plurality of connection brackets each have a lifting lug at a top end thereof.

[0021] In some embodiments, there is a T-section placed snugly along an interface between one or more pairs of adjacent panels.

[0022] In some embodiments, one or more of the panels have lower stiffener angles along their lower edges.

[0023] In some embodiments, one or more of the panels have upper stiffener angles along their upper edges.
[0024] In some embodiments, one or more pairs of adjacent panels each have upper stiffener angles, and a tie plate overlaps each of the two upper stiffener angles of the adjacent panels.
The tie plate may be removably attached to each of the two upper stiffener angles by removable fasteners.
[0025] Further aspects and example embodiments are illustrated in the accompanying drawings and/or described in the following description.

Brief Description of the Drawings [0026] The accompanying drawings illustrate non-limiting example embodiments of the invention.

[0027] Figure 1 shows an example modular liquid holding tank according to one embodiment comprising a plurality of arcuate panels held together by couplings.
[0028] Figure 2 is a top plan view of area A of Figure 1 showing portions of two adjacent arcuate panels and an example connection bracket cooperating to form a coupling according to one embodiment.

[0029] Figure 3 is a front elevation view of portions of adjacent panels according to one embodiment.

[0030] Figure 4 is a front elevation view of portions of adjacent panels according to another embodiment.

[0031] Figure 5 is a rear elevation view of a connection bracket according to one embodiment.

[0032] Figure 5A is a rear elevation view of a connection bracket according to another embodiment.

[0033] Figure 5B is a rear elevation view of a plurality of connection brackets according to another embodiment.

[0034] Figure 6 is a side view of a modular liquid holding tank according to one embodiment.

[0035] Figure 7 is an isometric view of one of the panels of the tank of Figure 7.
[0036] Figure 8 is a top view of the tank of Figure 6.

[0037] Figure 9 a top view of a modular liquid holding tank according to one embodiment.
[0038] Figure 10 is a top view of another embodiment of a modular liquid holding tank.
Description [0039] Throughout the following description specific details are set forth in order to provide a more thorough understanding to persons skilled in the art. However, well known elements may not have been shown or described in detail to avoid unnecessarily obscuring the disclosure. The following description of examples of the technology is not intended to be exhaustive or to limit the system to the precise forms of any example embodiment.
Accordingly, the description and drawings are to be regarded in an illustrative, rather than a restrictive, sense.

[0040] Unless the context clearly requires otherwise, throughout the description and the claims:
= "comprise," "comprising," and the like are to be construed in an inclusive sense, as opposed to an exclusive or exhaustive sense; that is to say, in the sense of "including, but not limited to" .

"connected," "coupled," or any variant thereof, means any connection or coupling, either direct or indirect, between two or more elements; the coupling or connection between the elements can be physical, logical, or a combination thereof.
= "herein," "above," "below," and words of similar import, when used to describe this specification shall refer to this specification as a whole and not to any particular portions of this specification.
= "or," in reference to a list of two or more items, covers all of the following interpretations of the word: any of the items in the list, all of the items in the list, and any combination of the items in the list.
the singular forms "a", "an" and "the" also include the meaning of any appropriate plural forms.

[0041] Words that indicate directions such as "vertical", "transverse", "horizontal", "upward", "downward", "forward", "backward", "inward", "outward", "vertical", "transverse", "left", "right" , "front", "back" , "top", "bottom", "below", "above", "under", and the like, used in this description and any accompanying claims (where present) depend on the specific orientation of the apparatus described and illustrated. The subject matter described herein may assume various alternative orientations. Accordingly, these directional terms should not be interpreted overly narrowly.
[0042] Figure 1 shows a modular liquid storage tank 100 according to an example embodiment. Tank 100 comprises a plurality of arcuate panels 12 held together by couplings 10. In the example shown in Figure 1, tank 100 has six panels 12 (individually numbered 12A-12F), but it is to be understood that tanks according to other embodiments may have different number of panels. Panels 12 may have insulation on the outer or inner surfaces thereof in some embodiments. The interior of tank 100 may be lined with a suitable water-tight liner (not shown) to hold liquids in tank 100, such that couplings 10 need not be water-tight. Each coupling 10 is effected by a connection bracket 20 which engages features on two adjacent panels 12 to form coupling 10, as described below with reference to Figures 2-5.
[0043] Tank 100 may be assembled directly on the ground. If the ground is not already level, a region of approximately the same shape and size of the footprint of tank 100 may be leveled. In some embodiments a frost cover is placed on the ground before tank 100 is assembled. In some embodiments a mat, such as a geomembrane or the like, may be placed on the ground (or on the frost cover, if present) before tank 100 is assembled.

[00441 In the illustrated embodiment the tank 100 is cylindrical with a circular cross section and the panels 12 are arcuate. However in other embodiments the tank may be oval, square, polygonal, or any other closed shape. The panels may be arcuate or straight or a combination thereof, depending on the shape of the tank.

100451 Figure 2 is a top plan view of area A of Figure 1 illustrating an example coupling 10 effected by a connection bracket 20 according to one embodiment. Each panel 12 has one or more protrusions extending outwardly therefrom along opposed vertical sides thereof to provide bearing surfaces 13 to facilitate coupling of panels 12 to each other as described below. In the illustrated example, protrusions are provided in the form of panel bars 14A
and 14B, which extend substantially along the opposed vertical edges of panels 12A and 12B, respectively. Panel bars 14A and 14B project outwardly from panels 12A
and 12B, respectively.
[00461 Connection bracket 20 comprises a pair of connection bars 24A and 24B
held in fixed relation to each other. In some embodiments, connection bracket 20 comprises an elongate plate 22, and connection bars 24A and 24B project inwardly and extend along substantially the entire vertical edges of elongate plate 22. Connection bars 24A and 24B
define a pair of opposed bearing surfaces 23 oriented generally parallel to one another. In the illustrated example, surfaces 23 are spaced apart by approximately the sum of the widths of panel bars 14A and 14B, such that surfaces 23 abut a corresponding pair of generally parallel bearing surfaces 13 defined by panel bars 14A and 14B. This configuration allows connection bracket 20 to be pushed over panel bars 14A and 14B to securely connect panels 12A and 12B.

100471 Panel bars 14A and 14B and connection bars 24A and 24B are generally rectangular in the illustrated example. In other embodiments bars 14A, 14B, 24A, and 24B
may have other shapes.
[00481 Connection bars 24A and 24B have beveled inward lateral edges 26A and 26B, respectively. Panel bars 14A and 14B have beveled outward lateral edges 16A
and 16B, respectively. These features facilitate push-on placement of bracket 20 over panel bars 14A
and 14B.

= -8-[0049] Apertures 15A and 15B extend through panel bars 14A and 14B, respectively.
Apertures 17A and 17B pass through connection bars 24A and 24B, respectively.
Rod 31 passes through apertures 15A, 15B, 17A, and 17B and holds bracket 20 in place.
A plurality of rods 31 may be provided. Rod 31 has apertures 11 A and 11 B defined through opposing ends. Apertures 11A and 11B may be configured to receive cotter pins, retaining bolts, or the like. In other embodiments apertures 15A, 15B, 17A, and/or 17B are threaded and a bolt (not shown) is inserted therethrough to hold bracket 20 in place. As one skilled in the art will appreciate, other means for holding bracket 20 in place may be used in other embodiments.

[0050] In some embodiments, panels 12A and 12B may fit snugly together without any significant gap therebetween. In other embodiments, there may be a gap between panels 12A
and 12B, and T-section 21 may be provided. T-section 21 fits snugly between plates 12A and 12B and extends along substantially all of the length of the interface therebetween. T-section 21 may prevent liner from being forced by water pressure into spaces between adjacent panels. T-section 21 may be made of elastomer, plastic, or any other suitable material.
[0051] Figure 2 also shows a lifting lug 28 on connection bracket 20, which is described in more detail with reference to Figures 5 and 6 below. In some embodiments, each panel 12 also has one or more lifting lugs (not shown) to facilitate movement and positioning of the panel 12.

[0052] Figure 3 is a front elevation view of portions of panels 12A and 12B.
Panel bars 14A
and 14B extend substantially along the entire vertical sides of panels 12A and 12B, respectively.
[0053] Apertures 15A pass through panel bar 14A, and corresponding apertures 15B pass through panel bar 14B. Rods such as rod 31, or other retaining elements may be inserted through apertures 15A and 15B (and corresponding apertures in bracket 20) to hold bracket 20 in place. In some embodiments apertures 15A and/or 15B may be threaded to receive bolts.

[0054] Figure 4 is a front elevation view of portions of panels 12A and 12B
according to another embodiment. In the Figure 4 embodiment panel bars 14A and 14B are broken up into three sections: panel bar sections 14A 1 and 14B 1, panel bar sections 14A2 and 14B2, and panel bar sections 14A3 and 14B3. In other embodiments panel bars 14A and 14B may be broken up into other numbers of sections, such as two, four, five, six, seven, eight, nine, ten, etc. The aggregate length of the panel bar sections should be at least 10% of the height of the panel. In some embodiments the aggregate length of the panel bar sections is more than 50% of the height of the panel. In some embodiments the aggregate length of the panel bar sections is more than 80% of the height of the panel.

[00551 Figure 5 is a rear elevation view of connection bracket 20. Apertures 17B pass through connection bar 17B, and corresponding apertures 17A pass through connection bar 17A. Each pair of apertures lines up with the corresponding pairs of apertures in panel bars 14A and 14B (see Figure 3), forming a set of four apertures through which a rod (such as rod 31 in Figure 2), bolt, or the like may be inserted. Figures 3, 4, and 5 show three sets of apertures, but in other embodiments of the invention there may be other numbers of sets of apertures, such as one, two, four, five, six, seven, eight, nine, or ten. In some embodiments, no such apertures are provided and bracket 20 may be held in place by other means. For example, in some embodiments, a socket, or the like, may be provided at the bottom of the interface between panels 12A and 12B for receiving the bottom of bracket 20, and a latch, or the like, may be provided at the top of the interface between panels 12A and 12B for holding the top of bracket 20 in place. In other embodiments, bracket 20 may be held in place by other suitable means, including for example bolts, straps, brackets, or other removable attachment means.

[00561 Lifting lug 28 extends from the top of elongate plate 22. Lifting lug 28 can be used to facilitate placement of the connection bracket 20 by a crane or other lifting device. Lifting lug 28 contains an aperture 32 which may be engaged by a hook, strap, or other connection component.

[00571 Figure 5A is a rear elevation of connection bracket 20A, which is an alternative embodiment of connection bracket 20. Connection bracket 20A does not have elongate plate 22. Connection bracket 20A has a plurality of rungs 22A which extend between connection bars 24A and 24B, and which are attached to connection bars 24A and 24B and hold connection bars 24A and 24B in fixed relation to each other.

[00581 Figure 5B is a rear elevation of a plurality of connection brackets 20B, which may be used an alternative to connection bracket 20 or 20A. Connection brackets 20B
comprise three bracket sections 20B 1, 20B2, and 20B3, which may be used to couple two adjacent panels together. Each of bracket sections 20B 1, 20B2, and 20B3 is similar to connection bracket 20, only shorter in length and without a lifting lug. Bracket sections 20B 1, 20B2, and 20B3 can be attached to panel bars 14A and 14B in a similar fashion to connection bracket 20. In other embodiments, bracket sections 20B 1, 20B2, and 20B3 are not of equal length. In other embodiments, other numbers of bracket sections may be used to effect a coupling between adjacent panels, such as two, four, five, six, seven, eight, nine, ten, etc.
[0059] Figure 6 shows a front elevation view of a modular storage tank 100' according to another example embodiment. Tank 100' is substantially similar to tank 100, except that in tank 100' each panel 12' (individually numbered 12A'-I2C) has upper and lower circumferential stiffener angles (also known as "shell angles" or "shell stiffeners") 34 and 35 (individually numbered 34A-35C and 34A-35C), respectively. Stiffener angles 34 and 35 extend substantially along the upper and lower edges of each panel 12', respectively.

[0060] Upper and lower stiffener angles 34 and 35 project outwardly from the panels 12'. In some embodiments one or both of the upper and lower stiffener angles may project inwardly from the panels.

[0061] Upper stiffener angles 34 do not project so far outwardly from the panels 12' that they interfere with the operation of lifting lugs 28. In some embodiments upper stiffener angles 34 project outwardly by a distance less than a distance between lifting lugs 28 and panels 12 when connection brackets 20 are in place. In some embodiments upper stiffener angles 34 project outwardly by variable amounts such that the distance of projection of upper stiffener angles 34 is relatively lesser in the regions which are close to lifting lugs 28 and relatively greater in the regions which are not close to lifting lugs 28.

[0062] Upper and lower stiffener angles 34 and 35 provide several benefits.
Both contribute to the overall structural integrity of the tank and to the structural integrity of the panels during handling, assembly, disassembly, and transportation. Upper stiffener angle 34 stiffens the top edge against wind loads. Lower stiffener angle 35 distributes the bearing load of the panels 12' and contributes to the stability of a single panel which has been placed upright but has not yet been connected to adjacent panels.

[0063] In some embodiments, L-brackets (also referred to as L-irons or angle brackets, not shown) may be provided at the interface between adjacent panels. For example, an L-bracket may be attached to each of an adjacent pair of panels 12' near the tops thereof, such that one "arm" of the L-bracket is attached to the outside wall of each adjacent panels 12', and the other "arm" of the L-bracket is attached to the underside of each upper stiffener angle 34.
Similar L-brackets may be provided at the bottoms of panels 12'. In embodiments where L-brackets are provided, connection bars 20 may be sized and shaped to accommodate the L-brackets (e.g., connection bars 20 may not extend all the way to the tops and or bottoms of panels 12').

[0064] Figure 7 shows a single panel 12A' of modular storage tank 100' of Figure 6. Upper and lower stiffener angles 34A and 35A project outwardly from panel 12A'.

[0065] Figure 8 shows a top view of modular storage tank 100'. Tie plates 39 (individually labeled 39A-39F) are provided between each pair of adjacent panels 12' (not visible in this view). Each tie plate 39 overlaps the upper stiffener angles of each pair of adjacent panels, so that tie plate 39A overlaps upper stiffener angles 34A and 34B, and tie plate 39B overlaps upper stiffener angles 34B and 34C, etc. Tie plates 39 may provide improved overall structural integrity to tank 100'.

[0066] Tie plates 39 may be removably attached to the upper stiffener angles 34 via bolts, screws, or any type of removable fastener. Tie plates 39 may be attached as each panel 12' is connected during the construction of the storage tank 100". Tie plates 39 may also be attached after all the panels 12' are connected.

[0067] Figure 9 is a top plan view of an alternative embodiment of a modular liquid holding tank 100". There are several panels 12", some straight (e.g. panels labeled 12A" and 12B") and some arcuate (e.g. panels labeled 12C" and 12D"). The panels are connected to adjacent panels by couplings 10. By changing the number of straight panels, the volume of the tank can be changed.

[0068] Figure 10 is a top plan view of an alternative embodiment of a modular liquid holding tank 200. There are four straight panels 51 arranged in the shape of a square.
Each panel 51 has two panel bars 52. The angle formed between the exterior of each panel 51 and its panel bars 52 is approximately 135 degrees. Each pair of adjacent panels 51 is held together by connection bracket 20.

[0069] In some embodiments a tank may be constructed from more than four straight panels 51, and the straight panels 51 are arranged into the shape of a regular polygon. In some embodiments the angle formed between the exterior of each panel 51 and its panel bars 52 is approximately:

180-180n2 2n where n is the number of panels 51.

[0070] Assembly of a tank, such as tank 100, 100', 100", or 200 as described above, may be accomplished using minimal equipment and labor, and without requiring any welding. The following sequence of steps may, for example, be followed to assemble a tank such as tank 100, 100', 100", or 200:
A. level an area of ground which is approximately the shape and size of the footprint of the tank to be assembled B. place a frost barrier directly over the leveled ground C. place a geomembrane directly over the frost barrier D. place a first panel on the geomembrane such that it stands upright E. ensure that the first panel remains balanced on its bottom edge, this may be accomplished by means of a temporary bracing structure, or by other means (e.g.:
being held in place by the bucket of an excavator) F. place a second panel next to the first panel in a lateral edge-adjacent orientation G. use a connection bracket's lifting lug to lift it with a crane or with other means H. orient the connection bracket directly in front of the panel bars 1. press the connection bracket over the panel bars such that it engages the panel bars and holds the panels together J. insert rods through the apertures of the connection bars and the panel bars K. insert cotter pins through the apertures in each end of the rods L. repeat steps F-K for all the panels necessary to assemble the complete tank M. place tie plates to overlap the upper stiffener angles of each pair of adjacent panels and connect the tie plates to the upper stiffener angles with bolts, screws, or other type of removable fastener N. place T-section between each pair of adjacent panels (in embodiments where there is an appreciable gap between panels) 0. place a liner inside the tank such that the tank can securely hold liquid.

[00711 Specific examples of systems, methods and apparatus have been described herein for purposes of illustration. These are only examples. The technology provided herein can be applied to systems other than the example systems described above. Many alterations, modifications, additions, omissions and permutations are possible within the practice of this invention. This invention includes variations on described embodiments that would be apparent to the skilled addressee, including variations obtained by: replacing features, elements and/or acts with equivalent features, elements and/or acts; mixing and matching of features, elements and/or acts from different embodiments; combining features, elements and/or acts from embodiments as described herein with features, elements and/or acts of other technology; and/or omitting combining features, elements and/or acts from described embodiments.

[00721 It is therefore intended that the following appended claims and claims hereafter introduced are interpreted to include all such modifications, permutations, additions, omissions and sub-combinations as may reasonably be inferred. The scope of the claims should not be limited by the preferred embodiments set forth in the examples, but should be given the broadest interpretation consistent with the description as a whole.

Claims (18)

WHAT IS CLAIMED IS:

1. A modular liquid storage tank comprising:
a plurality of panels arranged in lateral edge-adjacent fashion, each panel comprising a pair of opposed generally vertical sides each having one or more protrusions adjacent thereto extending outwardly from the panel, the protrusions defining opposed bearing surfaces extending, in aggregate, along at least 10% of a length of the generally vertical sides; and a plurality of connection brackets for coupling adjacent pairs of panels together, each connection bracket comprising a pair of connection bars held in fixed relation to one another and separated by a distance approximately equal to the spacing between the opposed bearing surfaces of protrusions of an adjacent pair of panels such that each connection bracket is operable to laterally confine the protrusions of the adjacent pair of panels, wherein the opposed bearing surfaces of the protrusions are parallel and have beveled outward lateral edges, and the connection bars comprise parallel opposed bearing surfaces having beveled inward lateral edges.

2. A tank according to claim 1 wherein the pair of connection bars are held in fixed relation to one another by an elongate plate, and wherein the connection bars extend inwardly from the plate along opposed longitudinal edges of the plate.

3. A tank according to claim 1 wherein the pair of connection bars are held in fixed relation to one another by a plurality of rungs, each rung being attached to both connection bars.

4. A tank according to any one of claims 1-3 wherein the panels are arcuate and the tank is cylindrical with a generally circular cross section.

5. A tank according to any one of claims 1-3 wherein the panels are straight and the tank is generally in the shape of a regular polygon.

6. A tank according to any one of claims 1-3 wherein:
two or more panels are arcuate, two or more panels are straight, and the panels are arranged in a configuration such that additional straight panels may be added to increase the volume of the tank.

7. A tank according to any one of claims 1-6 wherein the one or more protrusions comprise a panel bar extending outwardly from the panel along substantially an entire length of each of the generally vertical sides.

8. A tank according to any one of claims 1-6 wherein the one or more protrusions comprise a plurality of panel bar sections extending outwardly from the panel spaced apart along each of the generally vertical sides.

9. A tank according to claim 7 or 8 wherein:
the panel bars or panel bar sections are generally rectangular; and the connection bars are generally rectangular.

10. A tank according to any one of claims 1-9 wherein:
the connection bars of a connection bracket define one or more sets of aligned apertures, and wherein the one or more protrusions on adjacent edges of adjacent panels define one or more sets of corresponding aligned apertures, further comprising a plurality of retaining elements insertable through the aligned apertures of the connection bars and the protrusions on adjacent edges of adjacent panels to hold the connection bracket in place.

11. A tank according to claim 10 wherein each of the retaining elements comprises a rod.

12. A tank according to claim 11 wherein the rod has a hole through each end which is configured to receive a cotter pin.

13. A tank according to claim 10 wherein each of the retaining elements comprises a bolt, and wherein one or more of the aligned apertures are threaded to receive the bolt.

14. A tank according to any one of claims 1-13 wherein the plurality of connection brackets each have a lifting lug at a top end thereof

15. A tank according to any one of claims 1-14 comprising a T-section placed snugly along an interface between one or more pairs of adjacent panels.

16. A tank according to any one of claims 1-15 wherein one or more of the panels have lower stiffener angles along their lower edges.

17. A tank according to any one of claims 1-16 wherein one or more of the panels have upper stiffener angles along their upper edges.

18. A tank according to claim 17 wherein:
one or more pairs of adjacent panels each have upper stiffener angles; and a tie plate overlaps upper stiffener angles of one or more of the pairs of adjacent panels, the tie plate being removably attached to the upper stiffener angles by removable fasteners.