AU642822B2 - Improved storage tank - Google Patents

Description

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AUSTRA^A4 82 P/00/0O1 laon 3.2 PATENTS ACT 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT Name of Applicant: Address of Applicant: Actual Inventor: Address for Service: PIONEER WATER TANKS (AUSTRALIA) PTY.

LTD.

32 Goodwood Parade Rivervale 6103, Perth Western Australia, Australia JOHN PENGLASE 23 Toorak Road Rivervale 61 n. Perth Western Australia, Australia GRIFFITH HACK CO.

256 Adelaide Terrace Perth 6000 Western Australia, Australia .di Standard Complete Specification for the invention entitled: IMPROVED STORAGE TANK Details of Associated Provisional Applications: Details of Parent Application for Divisional Applications: 52474/90 filed March 30, 1990 The following is a full description of this invention, including the best method of performing it known to me:- -2- IMPROVED STORAGE TANK The present invention relates to an improved storage tank which is demountable and transportable.

The present invention will herein after be described with particular reference to corrugated panels in storage tanks, although it is to be understood that other profiles of panels could be used, such as, for example, smoothly curved panels.

It is to be noted that any panels used preferably do not have vertically disposed profiles, such as, for example, corrugations or channels. Vertical profiles are not to be used since they lead to shortening of the panels about the curved surface of the storage tank. Such shortening of the panels may allow the force of water or the like in the storage tank to distort the profiles and lengthen the panels. It is envisaged that lengthening of the panels may lead to rupture of the storage tank due to the momentum created by the water in lengthening the panels.

Accordingly, it is is preferably that profiling disposed substantially horizontally when the panels are in use.

Corrugated storage tanks in the past have been factory fabricated and then transported to a location for use. This sets a limit on the size of tank that can be used since it is generally uneconomical to fabricate such tanks on site and also sets a limit on the size of tank that can be transported legally and economically.

Such prior art corrugated storage tanks are constructed by joining a plurality of longitudinally curved corrugated sheets of metal end wise to form rings of a desired circumference. The joints are effected by rivets and soldering. Flat sheets are then joined to a lower lip of a first ring to form a flat base.

A second ring of corrugated sheets is then formed in similar manner to the first ring and is then set upon the first ring such that only one corrugation of each of the first and second rings mate together by overlapping. Only one corrugation overlap is possible because the two rings have been preformed and a trough of a corrugation of the second ring is not of sufficient

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-3diameter to pass over a crest of a corrugation of the first ring.

The single corrugation overlap thus introduces a weakness into the prior art tanks and thus results in a structural limitation of the size and strength of such prefabricated tanks.

"Longitudinal" in the context of the present invention in relation to the sheets, means directed circumferentially with respect to the storage tank.

It is an aim of one aspect of the present invention to provide an improved storage tank which is demountable and reinforcable to attempt to overcome the above disadvantages. For this purpose the tank is formed from a plurality of rings. Each ring is formed of a plurality of sheets of material, such as, for example corrugated iron. The sheets are longitudinally curved and are partly secured together endwise to sustantially form a i first ring of the tank. Formation of a second ring is then commenced, a sheet at a time, by bolting further sheets upon the first ring. The formation of the second ring includes o o overlapping and interleaving the further sheets with the sheets of the first ring, followed by securing the sheets of the second ring at the interleave to complete the first ring. Further rings may similarly be formed. By such securing, substantial .I overlapping of vertically adjacent rings of sheets is possible.

S| The overlapping results in the tank having strengthening hoops at the overlaps of adjacent rings which increases the strength S-4-25 of the tank beyond that of conventional corrugated tanks. Also, Ir the tank is readily transportable and can be erected on site which allows for greater tank sizes. Further, multiple layers of sheets can be used to gain further strength for larger tank sizes.

Unanticipated problems with such a construction of tank were encountered with regard to alignment of holes of sheets at the overlap and interleave of vertically and endwise adjacent sheets and with multiple layers of sheets. It has been discovered that such problems occur because vertically adjacent rings have different radii. For example, in a tank having three rings, the bottom ring has a radius of say R metres, the middle 4 ring then has a radius of R x and the top ring then has a radius of R x y. The values of x and y depend on the thickness of the sheets, and are typically of the order of 0.01% to 0.2% of the radius, depending on the size of the tank and the thickness of the sheets. In a typical case the radius may be about 3 metres and the sheets about Imm thick. Each ring has the substantially same centre of curvature and hence the rings have different radii of curvature and thus different circumferences. Accordingly, to enable adjacent rings to be formed together holes provided in the sheets of the rings for this purpose must be generally aligned upon radii of the tank.

Typically, the sheets forming the different radius rings have the same length of curvature. Thus, the holes must be located at different distances from ends of the sheets depending on the ring within which the sheets are to be located.

It is to be noted that due to the nature of the formation of the rings each ring does not describe a perfect circle having a precise centre of curvature but have w at may 0 o be described as an effective centre of curvature. Instead each sheet of each ring is overlapped endwise and describes a stepped circle. Thus, the precise centre of curvature of each sheet is slightly offset from what may be referred to as an S o effective centre of curvature of the ring. The precise centres o of curvature of each sheet within a given ring describe a circle around the effective centre df curvature. The actual Soffset is of the order of the thickness of the sheets which is I very small in comparison to the radius of the tank.

Accordingly, in practice, in the context of the present invention the actual offset is immaterial due to the imperfections in sizes of the sheets when manufactured and imperfections in the location of the sheets in situ. Thus, for the purposes of the present invention the rings and the sheets within the respective rings are considered to have substantially a single centre of curvature.

According to one aspect of the present invention there is provided an improved storage tank having an endless wall formed of a plurality of rings located vertically upon 4a each other, each ring having a constant average diameter over its width, each ring being formed of a plurality of curved sheets of material, the ends of each sheet of material being aligned with and partly overlapped with the ends of vertically adjacent sheets of material, the plurality of the sheets of material each having holes formed in them by a die, the holes being located adjacent the periphery of the sheets of material, said holes being capable of being in register when two or more sheets of material overlap and/or interleave for receiving fastener means, wherein the holes of overlapped and/or interleaved sheets are aligned upon radii of the storage tank, and the sheets of material are secured together by the fastener means when located in the holes, to form the completed storage tank, and wherein the die circumferentially displaces the holes in the sheets of material of adjacent rings for effecting alignment of the holes upon radii of the completed storage tank.

20 According to another aspect of the present invention there is provided a method for erecting an improved storage tank having a plurality of rings each having a plurality of sheets of material overlapped and interleaved and secured together with fastener means, the method comprising the steps of forming a first ring of sheets by loosely securing a plurality of sheets of material together endwise over all but an upper portion of their ends, forming further rings of sheets by overlapping vertically further sheets of material along their sides, interleaving said further sheets of material with 2 30 the upper portions of the ends of the sheets of material of the tring of sheets vertically there below and loosely securing the vertically adjacent rings of sheets together with fasteners, and tightening all of the fasteners.

According to a further aspect of the present invention there is provided a method of forming a plurality of sheets of material for forming a storage tank, the storage tank having an endless wall formed of a plurality of rings located vertically upon each other, each ring having a constant average diameter over its width, each ring being formed of a plurality

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of curved sheets of material whereby two or more of the sheets of material overlap and/or interleave for securing together with fastening means, the method comprising the steps of: aligning one of the sheets of material on a planar base of a die; securing the sheet of material to the base; adjusting the position of the die in relation to the sheet of material according to which ring of the storage tank the sheet of material is to form part of; S 10 operating the die to form holes proximate the periphery of the sheet of material; curving the sheet of material to a predetermined radius according to the diameter of the storage tank to be formed, whereby, the die position is adjusted so that the holes in sheets of material of adjacent rings are circumferentially displaced for effecting alignment of the holes of the sheets of material where they overlap and/or interleave.

According to a further aspect of the present invention there is provided an improved storage tank having an endless wall formed of a plurality of rings located vertically upon each other, each ring having a constant average diameter over its width, each ring being formed of a plurality of sheets of material, the sheets of material being formed according to the above said method, holes so formed in the sheets of material being capable of being in register when two or more sheets of material are overlapped and/or interleaved for receiving fastener means, wherein the holes of overlapped and/or interleaved sheets are aligned upon radii of the storage tank, and the sheets of material are secured together by the fastener means when located in the holes, to form the completed tank.

The overlapping of the rings effects tension hoops for the tank.

Preferably, the overlapped longitudinal sides of the sheets have holes and receive fastener means to join vertically adjacent sheets for forming the rings. Typically, for large tanks, multiple completely overlapping rings of sheets at and

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r:r 5a adjacent the lower reaches of the tanks may be used to double or triple, for example, the wall thickness of the tank.

Typically, the sheets of material are made from metal materials, although they could be made from plastics materials 5 or fibreglass or the like.

Prior art storage tanks also experience problems with regard to their roof means. In general prior art roof means comprise a central post which stands on a liner in the storage dj .it _~1i I -6tank. The post has a top flange from which generally triangular roof panels depend. The central post has a height adjustment means for raising and lowering the roof panels at the centre of the storage tank to achieve accurate lateral alignment of the roof panels. The adjustment means is located intermediate the length of the central post. The adjustment means is usually, when in use, immersed in the contents of the tank, which contents are usually water.

The disadvantage of such a roof means is that the adjustment means for the central post tends to corrode due to its immersion in the water. Once sufficiently corroded the adjustment means fails under the considerable force of the weight of the roof panels and the roof means collapses into the tank.

It is an aim of the present invention to also provide roof means for a storage tank to attempt to overcome these 4 disadvantages. A first roof means to meet this aim uses a sheet of flexible material, such as, for example a sheet of woven or non woven fabric, to cover the storage tank. The flexible material does not require height adjustment to function correctly and is relatively light. Accordingly, a plastic material support means may be used to support the sheet of Sflexible material. A second roof means employs roof panels and r l a a roof adjustment means which are supported above the contents of the storage tank and has no components located in the contents 2l5 of the tank. Also, the integrity of the roof adjustment means Ott. is not essential to maintain the roof panels above the said contents.

4 "According to a further- aspect of the present invention 64 there is provided a roof means for a storage tank having an endless wall, the roof means comprising a support means made of corrosion resistant material, the support means being located within the storage tank, a plurality of guys locating the support means upright in the storage tank, and a sheet of flexible material draped over the guys and secured to the endless wall.

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I:i 1 9 i i i B i:1 14 ir 1 i.- I i i::S i:: -7- According to a fourth aspect of the present invention there is provided a roof means for a storage tank having an endless wall, the roof means comprising a plurality of roof purlins, a roof adjustment means supported upon' the purlins, a plurality of roof panels disposable when in use, upon the endless wall and the roof adjustment means, whereby height adjustment of the roof adjustment means relative to the endless wall effects side by side alignment of adjacent ones of the roof panels.

According to a fifth aspect of the present invention there is provided a method of erection of a roof means upon a storage tank having an endless wtil, the roof means having a plurality of roof panels and drive cleats therefor, the method comprising the stpeos of coupling the purlins together and locating them upon the endless wall, disposing the roof adjustment means upon the purlins, locating the roof panels to span across the endless wall and the roof adjustment means, adjusting the roof adjustment means to raise and/or lower the roof panels such that adjacent roof panels are aligned edgewise together and coupling adjacent roof panels together.

Preferably, said roof adjustment means comprises a support element for supporting said roof panels and a plurality of height adjustment means extending between respective ones of said roof portions and said support element wherein manipulation of said height adjustment means varies the height of the support element relative to the endless wall.

Preferably, each height adjustment means comprises a first member connected to one of said support element and a roof purlin, said first member including stop engagable with said first member at a plurality of positions along the length of the first member, and a second member for receiving the first member up to said stop, wherein adjustment of the position of the stop along the length of the first member varies the height of the support element relative to the endless wall.

Preferably, said first member comprises a threaded bolt and said stop is a nut threadingly engagable on said bolt.

Preferably, said second element comprises a hollow poSt for receiving said bolt up to said nut.

1 7a Preferably, said bolt depends from said support element and said hollow post is connected to said roof purlin.

Preferably, said support element comprises a ring.

Preferably, the roof means has drive cleats to connect adjacent panel members together and inhibit ingress of water between the panel members.

Preferably, the roof means has a mesh screen and a top hat disposed to ventilate the storage tank and inhibit ingress of water and insects and the like.

A preferred embodiment exemplifying the present invention will now be described, with reference to the accompanying drawings, in which:- Figure 1 is a perspective view seen from above of endless wall of an improved corrugated storage tank in accordance with the present invention, the storage tank having a bottom, a middle and a top ring of sheets of corrugated o4 material; 4 a a Li -8- Figure 2 is a cross sectional view of the bottom ring of the endless wall of Figure 1 taken on Lines 2-2; Figures 3a to 3c are side views of three sheets of corrugated material of the endless wall of Figure 1, shown from their convex side, the sheets being for the bottom ring, the middle ring and the top ring, respectively; Figure 4a is a cross sectional view of the middle ring of the endless wall of Figure 1 taken on lines 4a 4a; Figure 4b is a cross sectional view of an overlap of sheets of material of the middle ring of the endless wall of Figure 1 taken on lines 4b-4b and showing double thicknesses for I each of the sheets of material; Figure 5 is an upper perspective vi w from above of a roof means of the present invention shown attached to the endless wall of Figure i, and shown with a part of a sheet of flexible material of the roof means broken away; Figure 6 is an perspective view fl ,m above of a foot Sof a centre post of the roof means of Figure Figure 7 is an explode view of another embodiment of a roof means according to the present invention; i Figure 8 is an perspective view from above of the endless wall of Figure 1, shown with the roof means of Figure 7 attached; i Figure 9 is an enlarged view of a purlin support S 25 bracket and purlin of the roof means of Figure 7; and, Figures 10a to 10c show steps in construction of the roof means of Figure 7.

In Figure 8 there is shown a storage tank 10 in accordance with the present invention. The storage tank comprises an endless wall lla, a roof means l1b and a liner means llc.

The endless wall 1la is formed of a plurality of rings 12 as shown in Figure 1. In the preferred embodiment the endless wall 1la has three rings 12, being a bottom ring 12a, a middle ring 12b and a top ring 12c. The rings 1r are formed vertically I:

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-9upon each other substantially about a central axis 13 of the endless wall. Each of the rings 12 is formed of a',plurality of sheets of corrugated iron 14. The sheets 14 are curved longitudinally and corrugated transversely.

The sheets 14 include bottom sheets 14a, middle sheets 14b and top sheets 14c being for the bottom ring 12a, the middle ring 12b and the top ring 12c, respectively. Each sheet 14 has two sides 15 parallel to the longitudinal axis of the sheet 14, and two ends 16 at right angles to the sides 15. The bottom sheet 14a has two sides 15a and 15b and two ends 16a and 16b as shown in Figure 3a. The middle sheet 14b has two sides 15e and and two ends 16c and 16d as shown in Figure 3b. And the top sheet 14c has two sides 15e and 15f and two ends 16e and 16f as shown in Figure 3c. Each sheet 14 has a plurality of holes located about its periphery. Typically, the holes 17 are located r upon crests of the corrugations of the sheets 14.

0 Each of the bottom sheets 14a comprises two rows of holes 17a and 17c located adjacent the end 16a and two rows of holes 17b and 17d located adjacent the end 16b. Each bottom sheet 14a also comprises a plurality of spaced apart holes 17e located along the side 15b between the rows of holes 17c and 17b.

Typically, there are ten holes in each row of the two rows of "I holes 17a to 17d. Typically, there are two holes 17e located on the second corrugation in from the side :4,:25 Each of the middle sheet 14b comprises a row of holes '2 18a located adjacent the end 16c and a row of holes 18b located adjacent the end 16d. Typically, two further iows of holes 18c and 18d are provided parallel to and spaced to the right of the 44 rows of holes 18i and 18b, respectively. The row of holes 18c typically has two holes 18ca located toward the side 15c, a hole 18cb located intermediate the row of holes 18c and two further holes 18cc located toward the side 15d. The row of holes 18d is similarly provided witIL holes 18da, 18db and 18dc. Two further holes 18e are located between the rows of holes 18c and 18b and adjacent the side 15c and two still further holes 18f are located between the rows of holes 18c and 18b typically on the second P i ii*---...r-~i*iY~.iYTIIII~-YLC~LXIIII i i II i ~i 10 corrugation in from the side Each of the top sheets 14c comprises a ro 4 of holes 19a located adjacent the end 16e and a row of holes 19b located i adjacent the end 16f. Typically, a row of two holes 19d is located parallel to and to the right of the row of holes 19a and a similar row of two holes 19c is located parallel to and to the i right of the row of holes 19b. Two further holes 19f are located between the rows of holes 19c and 19b and adjacent the side As can be seen by comparing the Figures 3a to 3c the rows 17a, 18a and 19a are staggered relative to each other. The staggering is outwardly toward che adjacent ends 16 with respect j to the row of holes 17a. The rows of holes 17c, 18c and 19c are staggered similarly. The rows of holes 17b, 18b and 19b and the i rows of holes 17d, 18d and 19d are staggered in a similar manner i 5 to the rows of holes 17a to 19a and 17c to 19c respectively. The staggering is shown exaggerated for clarity in Figures 3a to 3c.

Typically, for sheets 14 of about 3000mm in length the staggering Sis about 0.75mm between vertically adjacent rows of holes 17, such as, for example between the row of holes 17a to 18a. The staggering of the rows of holes 17 is essential to the working of the invention, as described in greater detail hereinafter.

The ring 12a is formed by overlapping adjacent ones of the sheets 14a to form a circle as shown in figure 2. The row of hole 17a of one of the sheets 14a is disposed to overlie the S 25 row of holes 17b on the sheet 14a. Accordingly, the rows of holes 17c and 17d of the two sheets 14a also overlie. Bolts constituting fastener means for the present embodiment, are located in the underlying rows of holes 17a and 17b, and 17c and 17d and fixed in placd with ncits 20a. Typically, the bolts are fitted through the rows of holes 17b and 17d and then through the holes 17a and 17c respectively. That is the bolts 20 are passed from within the endless wall 1la to without. The nuts are threaded upon the bolts 20 to secure the adjacent sheets 14a together to complete the ring 12a.

The rings 12b and 12c are formed similarly to the sheets 14b and 14c respectively. There is however a difference 11 in the method of formation of the rings 12b and 12c as described hereinafter.

As shown in Figure 4a the ring 12b has its sheets 14b overlapped with the sheets 14a. That is the side 15c of each sheet 14a and overlap with the side 15b of each vertically adjacent sheet 14b. The ends 16 of the sheets 14a and 14b overlap and interleave. That is the ends 16a and 16b overlap along most of their length, whilst at the join between the two rings 12a and 12b the end 16d is interleaved between the ends 16a and 16b and the end 16a is interleaved between the ends 16c and 16d. Thus, at the longitudinal and transverse juncture of two adjacent sheets 14a with two vertically adjacent sheets 14b, referred to as juncture J1, there are four sheets 14.

As shown in Figure 1 the four sheets 14 at juncture J1 comprise a bottom sheet 14a (sheet a middle sheet 14b (sheet another bottom sheet 14a (sheet C) and another middle sheet 14b (sheet That is holes 17aa and 17ca of the sheet A overlie with holes 18aa and 18ca of the sheet B and *o with holes 17ba and 17da of the sheet C and with the holes 18ba *o and 18da. These holes are referred to collectively as the holes 17 at the juncture J1.

6 0 It is important to note that the sheets 14b are at greater distances from the central axis 13 of the endless wall .o 11 than the sheets 14a. That is the radius of curvature of the sheets 14b is greater than the radius of curvature of the 0f 0 sheets 14a. Thus, to achieve accurate overlying of the holes 17 at the juncture J1, to enable location of the bolts therein, the respective holes 17aa and 18aa, 17ca and 18ca, 17ba and 18ba, and 17da and 18da must align substantially upon .radii of the endless wall lla (which may also be referred to as radii of the storage tank 10). The aligning upon the radii of the endless wall lla is achieved by the staggering of the holes 17 referred to hereinabove. It has been surprisingly discovered, that where the location of the holes 17 on each sheet 14a, 14b and 14c is identical location of the bolts in the holes 17 becomes very difficult and in some cases impossible. i i 12 It is known to force a spike in the holes to assist in achieving alignment of holes in sheets. However, it was foand that even the use of spikes was unsuccessful in attempting to force alignment of such identically located holes. In fact it was discovered that in some cases the metal of the sheets was deformed or tore before alignment of the holes could be achieved.

The sheets 14c of the top ring 12c are overlapped and Sinterleaved with the sheets 14b of the middle ring 12b in similar manner to the overlapping and interleaving of the sheets 14a and 14b described hereinabove. Also, there are four sheets 14 (call them sheets B,D,E, and F) at a juncture J2 (see Figure 1) similar to the juncture J1. At the juncture J2 holes 18ab and 18cc of ii the sheet B overlie with holes 19aa and ,9c of the sheet E, and Sholes 18bb and 18dc of the sheet D overlie with holes 19ba and 19d of the sheet F. These holes are referred to collectively as the holes 17 at the juncture J2. The respective holes 18ab and S19aa, 18cc and 19c, 18bb and 19ba, and 19d are aligned 1 substantially upon radii of the endless wall 11.

The holes 17e and 18e, 18f and 19e along the sides of the sheets 14 are also aligned upon radii of the endless wall 1la. That is the holes 17e and 18e align with each other, as do the holes 18f and 19e.

As shown in figure 14b each of the sheets 14a and 14b may, as shown in Figure 4a, be replaced with two such sheets 14a and 14b. Accordingly, the endless wall la is thicker where the doubled layers of sheets 14a and 14b are used. The doubled layers increase the strength of the endless wall 1la. The arrangements of the holes 17 for securing each sheet 14 together is the same as described herein above.

The storage tank 10 also comprises a liner 22 constituting the liner means lic. Typically, the liner 22 is made of UV stabilised polyethylene and is sized greater than the tank 10 so as to easily conform to the corrugations of the sheets 14. Preferably, the liner 22 is black to inhibit growth of algae. The liner 22 is conveniently fixed to a lip 24 of the endless wall 1la by a strip of plastic 26 or the like (see Figure

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13 Typically, screws are used to fix the strip 26 to the lip 24. Preferably, the storage tank 10 is lined with tape 29 and/or material or the like to cover the bolts 20a and overlapped edges of the sheets 14 where they protrude into the interior of the tank 10 so as to protect the liner 22 from puncture thereby, as shown in Figure 1.

In one form of the invention the roof means llb is in the form of a roof assembly 30 shown in Figure 5. The roof assembly 30 has a centre post 31 with a foot 32 disposed to rest upon the liner 22 as shown in Figure 6. The post 31 is made of plastics material and typically has its length fixed. Typically, S a layer of plastics material 33 is disposed between the foot 32 and the liner 22. The post 31 also has a top 34 with holes to receive guys 36. The endless wall 1la has cleats 38 stationed adjacent the lip 24 to which one end of the guys 36 is fixed.

A flexible sheet material roof 40 is then draped over the guys 36. The sheet material roof 40 is typically formed of plastics material or the like and may be fixed to or adjacent to the lip o o 24 by a draw string 41 or lashings or the like. The sheet 'oo' 20 material roof 40 is relatively light and is readily supported by the post 31 and the guys 36.

According to another embodiment of the present on.

.ooo invention there is a roof means lb in the form of a roof assembly 42 particularly as shown in Figures 7 and 8. The roof 25 assembly 42 comprise a plurality of roof purlins 44, purlin struts 46, purlin support brackets 48 and a centre yoke 50. Each of the purlin support brackets 48 are fixed, such as by bolting, Sto one end of each roof purlin 44 (see Figure The other end of each roof purlin 44 is connected to the centre yoke 50 as shown in Figures 10a to 10c. Typically, there are four radiall; oriented roof purlins 44 although other numbers of roof purlins 44 could be used. It is also envisaged that the roof purlins i could be other than radially disposed, such as disposed upon cords, of the endless wall 1la, in which case the roof purlins 44 would not be terminated at the central yoke 1/6 14- The roof assembly 42 also comprise a roof adjustor 52 in the form of a support element or roof adjustment ring 54. The roof adjustment ring 54 includes a height adjustment means comprising a first member which may be in the form 'bf threaded bolts 56 depending co-directionally upon the ring 54.

Preferably, the roof adjustment ring 54 can be separated into two or more segments for ease of transport. Each bolt 56 has stop in the form of an adjustment nut 58 threadingly engaged upon it.

The height adjustment means also comprises a plurality of second members in the form of hollow posts 60 for receiving respective ones of bolt 56 up to a corresponding nut 58. Typically, one of the hollow posts 60 is fixed, such as by bolting to a respective one of the roof purlins 44 as shown in Figures 8 and 10a to %~The bolts 56 locate in respective ones of the hollow posts 60 and the nuts 58 bear against the hollow posts 60. Threading of the nuts 58 along the bolts 56 causes raising and lowering of the roof adjustment ring 54. The amount of raising and lowering about the circumference of the roof adjustment ring 54 can be controlled by the amount of threading of the respective nuts 58 on the bolts 56. That is the roof adjustment ring 54 can be raised and lowered by varying amounts.

The roof assembly 42 also comprises a plurality of roof panels 62 of generally trapezium-like shape in plan and each having a substantially stretched shaped cross section. Each roof panel 62 is substantially flat between its ends 62a and 62b as shown in Figures 7 and. 8. Fasteners, such as bolts and nuts are provided to fix adjacent panels 62 together. Drive cleats 64 having a shape complementary to the shape of the junction of adjacent panels 62 are also provided to fix adjacent panels 62 together. The drive cleats 64 fix adjacent panels 64 together contiguously and inhibit the ingress of water through the roof assembly 42. The roof assembly 42 also comprises a top hat 66 and a mesh screen 68. The mesh screen 68 is typically shaped in cross section and circular in plan. The mesh screen 68 is conveniently screwed to the panels 62 at their ends 62b. The top hat 66 has a central fixing bolt 70 which thread into the central yoke 50 (or otherwise to or adjacent one of the roof purlins 44) to secure the top hat 66 atop the mesh screen 68. The top hat_- 15 66 is sized to overlie the mesh screen 68 and a part of the roof panels 62 to allow for passage of air through the toof means 42 whilst inhibiting the passage of water such as rain into storage tank 10. That is, the mesh screen 68 allows venting of water vapour from within the storage tank 10 and hence reduces the moisture levels and corrosion therein, whilst providing a barrier to insects.

The roof assembly 42 further comprises a top edge angle 71 formed from lengths of angle material which is longitudinally 1 0 curved and having slots (not shown). The top edge angle 71 is Salso shaped in cross section with a middle 71a of the "z" disposable parallel to the sheets 14c and the ends 71b and 71c of the disposable at right angles to the sheets 14c, as shown in Figure 9. The end 71b is intended to seat into a trough of one of the corrugations proximate the lip 24. The end 71c is intended to sit flush with the lip 24 so as to support the purlin support bracket 48 and to allow fixing of the purlin support bracket 48 to the top edge angle 71.

The storage tank 10 also typically has an outlet and i 20 all overflow located in one of the bottom and top sheets 14a and 14c respectively. The outlet and overflow are of conventional i type as known in the art.

In use, the storage tank 10, in kit form, is taken to a site for assembly. The site is prepared by clearing a j 25 relatively flat and horizontal circle of ground. Preferably, about 100mm of self draining sand is spread over the site to aid .in water drainage and to avoid sticks or stones contacting the liner 22.

Formation of the bottom ring 12a can then commence.

The sheets 14a are set about the site and then stood up in position and overlapped, end 16a to end 16b. It is very important that the sheets 14a be overlapped in the same direction i (see Figure 2) as there will be considerable difficulty in constructing the rings 12b and 12c otherwise. The rows of holes 17a and 17c of the sheet C are overlayed with the rows of holes 17b and 17d, respectively, of the sheet A. The bolts 20 are then i 16 passed through and secured into these holes with the nuts At this stage the nuts 20a are preferably tightehed by hand, without tools. It is to be noted that the holes 17aa, 17ca, 17ba and 17da are not provided with bolts 20 at this stage. The remaining sheets 14a are coupled together as described herein above to partly form the bottom ring 12a. The ring 12a is then checked to determine how circular it is and the sheets 12a moved if necessary to achieve substantial circular shape in plan. The ring 12a is also checked to determine how for horizontal the sides 15b of the sheets 14a are, such as with a split level. The sheets 14a are moved up or down if necessary to achieve o substantial horizontal disposition of all of the sides 15b. It is important for ease of construction of the rings 12b and 12c that the ring 12a be circular in plan and disposed horizontally.

15 Before the bottom ring 12a is completed formation of the middle ring 12b is started. The end 16d of the middle sheet B is interleaved between the bottom sheets A C at the juncture J1. Bolts 20 are then inserted through the holes 17ba and 17da of the bottom sheet A, through the holes 18ba and 18da of the -20 middle sheet B and then through the holes 17aa and 17ca of the bottom sheet C. Nuts 20a are then temporarily threaded fingertight onto the bolts 20. Another one of the middle sheets ~14b, call it sheet G, is then selected. The end 16d of the middle sheet G is interleaved between the bottom sheet 14a, call 25 it sheet H, adjacent the bottom sheet A and to the left, and the bottom sheet A. The bolts 20 are then passed through the holes f 17ba and 17da of the bottom sheet H, through the holes 18ba and 18da of the middle sheet G, through the holes 17aa and 17ca of the bottom sheet A and through the holes 18aa and 18ca of the middle sheet B. The nuts 20a are then threaded fingertight upon the bolts 20. The remainder of the holes in the rows 18a, 18c, 18b and 18b except the holes 18ab, 18cc, 18bb and 18dc, may now be provided with further bolts 20 and secured with nuts 20a. The remainder of the middle sheets 14b are similarly connected upon the bottom ring 12a, until the middle sheet D is to be fitted into place. Once the end 16d has been bolted in place it is then 17 necessary to unthread the nuts 20a at the juncture J1 pass the bolts 20 thereat through the rows of holes 18a and"18c, but not the holes 18ab and 18cc. The bolts 20 then have the nuts rethreaded upon them as before.

The bottom ring 12a is now completed and the middle ring 12b partly completed.

Before the middle ring 12b is completed construction of the top ring 12c is started. The top sheet E is interleaved between the two middle sheets B and D (see figure Bolts are then passed through the holes 17 at the juncture J2 and the nuts 20a threaded thereonto, fingertight. The end 16f of one of the top sheets 14c, call it sheet I, is then interleaved between the end 16d of the middle sheet G and the end 16c of the middle sheet B. Bolts 20 are then secured with nuts 20a into the holes 18bb and 18dc of the middle sheet G, then through the holes 19ba and 19d of the top sheet I, then through the holes 18ab and 18cc of the middle sheet B and then through the holes 19aa and 19c of the top sheet E. Bolts 20 may then be secured by nuts 20a into the remainder of the holes of the rows of holes 19b and 19a of S 20 the top sheets I and E, respectively. The remainder of the top Asheets 14c may be secured in place upon the middle ring 12b until E the top sheet F is to be fitted in place. The top sheet F is fitted similarly to the last middle sheet D except that all remaining holes 17 of the top sheet F are bolted.

S 25 This completes the middle ring 12b and the top ring 12c. All of the bolts 17 may now be tightened with the aid of tools such as wrenches or shifters or the like.

In the preferred embodiment there is an overlap of 2% corrugations between adjacent rings 12a to 12c thus providing two horizontal rows of connecting bolts 20 coupling adjacent rings 12a to 12c together.

The construction results in two hoops extending around the endless wall 1la and integral with it. The lower hoop is formed by the overlap of the bottom ring 12a and the middle ring 12b. The upper hoop is formed by the overlap of the middle ring 12b and the top ring 12c. The hoops are, in the preferred 4 V-\ -18embodiment, 2Y corrugations wide and twice as thick as the i remainder of the endless wall Ila. The hoops produce added t resistance to hoop stresses developed in tY. endless wall lla when in use. Such added resistance is an important factor in considering the safe capacity of the storage tank The vertical overlapping of adjacent rings 12a to 12c U gives an increase in strength compared to that of conventional corrugated tanks where there is only a ring overlap between i rings since there rings are preformed and all have the same i radius and where the vertical overlap of panels is circumferentially staggered.

i The inside of the storage tank 10 is then lined with V the tape 29 and/or material to cover protruding heads of the g bolts 20 and to cover the overlapping sides 15 and ends 16 of the sheets 14. The liner 22 is then fixed to the lip 24 by the strip S26 and the screws.

i Preferably, sand bags are fitted to some of the sheets 14c and disposed inside the tank 10 to inhibit movement of the liner 22 during windy conditions when the tank 10 is empty.

Where larger tanks 10 are to be formed the rings 12a and 12b can be formed of greater thickness to improve tank strength by replacing each sheet with plurality of identical curved panels disposed in a mutually overlying relationship. For example, the thickness of ring 12a and 12b can be doubled by using two sheets 14a face to face in place of each sheet 14a and two sheets 14b face to face in place of each sheet 14b, as shown in Figure 4b. In such a case, the bottom ring 12a may be formed Iof sheets 14a 0.8mmmetal giving a thickness of 1.6mm, the middle ring 12b formed of sheets 14b of 0.6mm metal to give a thickness of 1.2mm and the top rings 12c formed of single sheets 14c of 0.8mm metal. This results in a first hoop of 4 layers of metal at the join of the bottom and middle rings 12a and 12b with a thickness of 2.8mm, and a second hoop of 3 layers at the join of the middle and top rings 12b and 12c with a thickness of The endless wall Ila then has a profile of thickness 1.6mm over most of the bottom rings 12a, 2.8mm at the first hoop, 1.2mm over most of the middle ring 12b, 2.0mm at the second hoop and 0.8mm over the remainder of the top ring 12c.

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t 19 At the juncture J1, for the above example, there is a thickness of 5.6mm constituted by two bottom sheet's 14a and two middle sheets 14b. At the juncture J2 there is a thickness of constituted by two middle sheets 14b and one top sheet 14c.

Due to the considerable thicknesses of metal at the junctures Jl and J2 and the relatively large number of overlapping sheets 14 accurate alignment of the holes 17 is essential.

It is envisaged that the instant storage tank 10 could range in size from 1.8mm to 20m in diameter, more typically 3m to 12m.

One of the roof assemblies 30 or 42 may then be assembled on the storage tank 10. Where the roof assembly 30 is used the material roof 40 is fixed about the sheets 14c adjacent the lip 24. Then the guys 36 are fixed to the cleats 38 and to the top 34 of the centre post 31. The centre post 31 is then raised to lift the material roof 40 to place the foot 32 onto the layer of material 33. The guys 36 are then adjusted to be taught.

2 Where the roof assembly 42 is used the following assembly procedure is preferred. Fix the purlin support brackets 48 to an end of respective ones of the roof purlins 44 as shown in Figure 9. Then fix the hollow posts 60 to the respective roof purlins 44 as shown in Figures 10a to 10c. Then, fix two of the roof purlins 44 onto opposite sides of the centre yoke 50 and S: 25 couple one of the purlin struts 46 between the two roof purlins 44. Lie the assembled purlins 44 and yoke 50 on the lip 24 of i i the storage tank 10, as shown in Figure 10a and fix another roof Spurlin 44 to the yoke 50. The last fitted roof purlin 44 can be used to push all three assembled roof purlins 44 atop the storage tank 10 with the purlin support brackets 48 seated over the lip 24. The purlin support brackets 48 may be attached to the top edge angle 71 such as with screws. The remaining roof purlin 44 and purlin strut 46 are then attached to the yoke 50 and the other roof purlin 44 respectively. The roof adjustment ring 54 is then place on top of the roof purlins 44 with the threaded bolts 56 inserted into the hollow posts 60 so that the adjustment i L i 1 r_ -rripu~*

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nuts 58 bear against the hollow posts The roof panels 62 are next located spanhing from the top edge angle "71 across the roof adjustment ring 54 towards the central axis 13 as shown in Figure 8. A first one of the roof panel 62 is fixed at its centre to the top edge angle 71 to provide a reference point for laying the remainder of the roof panels 62. The next roof panel 62 is laid adjacent the first roof panel 62 and one of the drive cleats 64 is forced over the mating sides of the two panels 62. Preferably, one screw is also used adjacent an outer end of the two panels 62 to inhibit relative longitudinal movement between the adjacent panels 63.

The remainder of the roof panels 62 are put in place in similar s, manner.

555 V In attempting to lay the last roof panels 62 there is usually experienced misalignment toward the end 62a of the first and last panels 62. This is usually due to manufacturing tolerances in all of the roof components and in the storage tank and inaccuracies in placement of all of the other roof panels 62. However, the adjustment nuts 58 can be rotated to both raise some of the panels 62 and lower others of the panels 62 in a continuous manner about the roof adjustment ring 54 to achieve S, accurate alignment of adjacent panels 62. In the context of the present invention accurate alignment of adjacent panels 62 means continuous contact between adjacent panels along their longitudinal sides. It is to be noted that the disposition of the roof adjustment ring 54 can be adjusted, by the nuts 58, in three dimensions.

SThe ends 62b of each of the panels 62 are then fixed to the top edge angle 71 with further screws adjacent panels 62 are screwed together adjacent the their ends 62a. The mesh screen 68 is then located at the end 62a of the panels 62 and screwed thereto. Next the top hat 66 is place to sit atop the drive cleats 64 and/or the mesh screen 68. The fixing bolt is then fixed into the centre yoke 50. This completes the construction of the roof assembly 42.

L.

21 21 It is envisaged that the tank 10 could be fixed, such as by bolting, to a concrete footing or base and sealed with silicone to obviate the need for the liner 22.

The holes 17 in the sheets 14 of the present invention are formed by punching them in a die having a base having a planar -cprrugated profile to receive flat corrugated sheets 14. The base reduces the likelihood of skewing and lateral displacement of the sheets 14 that could otherwise occur. The die also comprises clar~ps to fix the sheets 14 into position and punches to create holes 17 at predetermined centres. The posi.tions of the punches longitudinally on the sheets 14 are adjusted by o o offsetting for the various sheets 14a, 14b and 14c. The sheets oo 14 are then curved by passing them through a bending mandiil.

It is very important that the sheets of corrugated material 14 be "true" that is that the crests and troughs of the corrugations be at exactly equally spaced centres, so that the holes punched in adjacent sheets 14 match at crests or troughs.

In the method of the present invention all sheets 14 are checked Sfor accuracy of corrugation and rerolled if not sufficiently 0 20Q accurate.

The present invention enables relatively larger a, °o a o corrugated tanks 10 to be more easily formed on site. Also, the ooo tanks 10 have greater inherent strength and are more easily transported than prior art corrugated tanks. This is in part due to the hoops effected by the overlap of vertically adjacent rings 00 12. Construction is facilitated by the alignment of adjacent Sholes in the sheets 14 upon radii of the endless wall 1la. The overlap of the ends 16 of the sheets 14 effects vertical posts integral with the endless wall 11a. The posts are thicker than the remainder of the endless wall 1la, except the hoops, and so provide added vertical strength. Thus tie hoops and the posts form a relatively strong grid within which tihe remainder of the sheets 14 span.

The roof assembly 30 is advantageous in that it produces a pitch in the material roof 40 and so avoids collection of water and or debris in the material roof 40. Also, due to the 1 I I i 22inherent flexibility and light weight nature of the material roof no adjustment in the height of the centre port"31 is needed and so it can be made of plastic material and thus avoid the corrosion that plagues metal centre posts.

The roof assembly 42 overcomes the inherent problem of segmented rooves created by corrosion of centre posts when stationed in water. The adjustor 52 allows for accurate alignment of the roof panels 62 and is not stationed to be in water, when in use, and so avoids the corrosion problem. Also, should the adjustment means 52 were to fail the roof panels 62 remain supported by the roof purlins 44. Also, by the provision of the mesh screen 68 moisture levels in the storage tank 10 are 0*j reduced thus reducing corrosion of the roof means 42 and inhibiting entry of insects. Also, the roof panels are so shaped as to be nestable one with the other thus facilitating easier transport.

Modification and variations such as would be apparent to a skilled addressee are deemed within the scope of the present invention. For example, other quantities of holes 17 could be ri 20 used provided radial alignment of overlying holes is maintained.

,Also, other than three rings 12 could be used and other than eight o sheets 14 per ring 12 could be used. Further, one or more relatively narrow rings could be secured about the endless wall 1la to effect further tension hoops.

$0 4 a S

Claims (2)

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23- THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS:- 1. A roof for a storage tank having an endless wall, said roof comprising a plurality of roof purlins, a roof adjustment means supported upon the roof purling, a plurality of roof panels disposed upon the endless wall and the roof adjustment means, whereby alignment of adjacent ones of said roof panels can be effected by varying the height of the adjustment means relative to the endless wall. 2. A roof according to claim i, wherein said roof adjustment means comprises a support element for supporting said roof panels and a plurality of height adjustment means i extending between respective ones of said roof portions and said support element wherein manipulation of said height adjustment means varies the height of the support element relative to the endless wall. 3. A roof according to claim 2, wherein each height adjustment means comprises a first member connected to one of said support element and a roof purlin, said first member including stop engagable with said first member at a plurality i of positions along the length of the first member, and a second member for receiving the first member up to said stop, wherein adjustment of the position of the stop along the length of the first member varies the height of the support element relative to the endless wall. 4. A roof according to claim 3, wherein said first member comprises a threaded bolt and said stop is a nut threadingly engagable on said bolt. A roof according to claim 4, wherein said second element comprises a hollow post for receiving said bolt up to said nut. 6. A roof according to claim 5, wherein said bolt depends from said support element and said hollow post is connected to said roof purlin. c V -24 7. A roof according to any one of claims 2 to 6 wherein said support element comprises ring. i 8. A roof according to claim 2, in wich the roof adjustment means comprises a roof adjustment ring with threaded bolts depending axially therefrom having nuts threadingly engaged thereon, a plurality of hollow posts one fixed to each roof purlin, each hollow post receiving one of the threaded bolts, and the nuts bearing against the hollow posts for standing the roof adjustment ring above the purlins. 9. A roof according to any one of claims 1 to 8 further comprising a plurality of drive cleats shaped complementary to o the join between adjacent roof panels to locate same together in a sealing manner. 0. A roof according to any one of claims 1 to 9, further comprising a top hat disposed atop the roof panels and fixed by a fixing bolt to a junction of the purlins. m 11. A roof means according to claim 10, comprising a mesh screen disposed between the roof panels and the top hat for allowing passage of air into and out of the storage tank. 12. A method of erecting a roof upon a storage tank having an endless wall the roof having a plurality of roof Spurlins, a roof adjustment means a.id a plurality of roof panels and drive cleats therefor; including the steps of coupling the b( purlins together and locating them upon the endless wall, disposing the roof adjustment means upon the purlins, locating the roof panels to span across the endless wall and the roof adjustment means, adjusting the roof adjustment roof means to raise and/or lower the roof panels such that adjacent roof panels are aligned edgewise together and coupling adjacent roof panels together. 13. A roof according to any one of claims 1 to 11 substantially as herein described with reference to and as ii I_ 25 illustrated in Figures 7 to 10c of the accompanying drawings. 14. A method according to claim 12 substantially as herein described with reference to and as illustrated in Figures 7 to 10c of the accompanying drawings. Dated this 3rd day of June, 1992. s i Si: O 0l $0 PIONEER WATER TANKS (AUSTRALIA) PTY. LTD. By Its Patent Attorneys GRIFFITH HACK CO. Fellows Institute of Patent Attorneys of Australia. 4 00 4 0 0t <t 0 4 a a 0 a e 6 a PP'1Y 1 tl-*~l i ABSTRACT The specification discloses a roof for a storage tank having endless walls. The roof 42 comprises a plurality of roof purlins 44, and a centre yoke 50. Each purlin is 1 5 connected at one end to the centre yoke 50 and at an opposite end to the endless wall by means of support brackets 48. S Purlin struts 46 connect different pairs of roof purlins 44. i Supported on the roof purlins 44 is a roof adjusting ring 54. Roof adjusting ring 54 includes a plurality of downwardly I 10 extending bolts 56, each bolt having a nut 58 threadingly i engaged thereon. A hollow post 60 is connected to each roof 1' purlin and receives a length of a corresponding bolt 56 up to its nut 58. A plurality of roof panels 62 are supported at opposite ends between the endless wall of the storage tank and the roof adjusting ring 54. In order to achieve alignment of adjacent roof panels 62 the height of the roof adjusting ring i 54 above the endless wall of the storage tank can be varied by rotating the nuts 58. By appropriately adjusting the nuts 58 edges of adjacent roof panel 62 can be aligned and the panels 62 connected together. ii I Recommended drawing to accompany abstract: Figure 7. i i' i: