GB2156890A - Storage tank - Google Patents

Abstract

The tank (10) comprises an endless wall formed of a plurality of overlapping panel members (11) with at least one endless support strap (17) extending substantially horizontally around the endless wall, wherein each panel member (11) comprises a loop (16) having an endless support strap (17) extending therethrough. The panel members (11) may comprise a plurality of upright raised ribs and an integral loop. The tank is slated to be useable as a dwelling with the addition of doors, insulation and/or ventilation. <IMAGE>

Description

SPECIFICATION Storage tanks The present invention relates to storage tanks.

Storage tanks are usually built in situ or constructed and transported to a required location.

In particular large storage tanks are built in situ and often employ steel reinforced concrete. Whereas, tanksforthe storage of relatively small quantities of various liquids, solids or powders are often constructed and transported to a desired location for installation and use.

In general the latter form oftank may be removed and relocated for use elsewhere. However, tanks built in situ and comprising concrete are not usually intended to be relocated, nor can economically be relocated.

The present invention provides a storage tank which is built in situ and may be readily dismantled and relocated. In accordance with one aspect ofthe present invention there is provided a storage tank comprising an endless wall formed of a plurality of overlapping panel members with at least one endless support strap extending substantially horizontally around the endless wall, wherein each panel member comprises a loop having an endless support strap extending therethrough. In accordance with a further aspect ofthe present invention there is provided a substantially flat panel member comprising a plurality of upright raised ribs and an integral loop arranged to receive, in use, a substantially horizontal support strap.

The present invention will now be described, by way of example, with reference to the accompanying drawings, in which:- Figure lisa front elevation of a panel member in accordance with the present invention; Figure 2 is a side elevation ofthe panel member of Figure 1, shown in situ; Figure 3 is a cross sectional view of the panel member of Figure 1 along line A-A; Figure 4 is an enlarged view of a trough ofthe panel member shown in Figure3; Figure 5 is an elevated view of a storage tank in accorda nce with th e present invention; and Figure 6 is an upper perspective view of a support strap ofthe storage tank of Figure 5.

In Figure there is shown a storagetank 10 in accordance with the present invention, comprising a plurality of panel members 11.

As can be readily seen in Figure 1, each panel member 11 comprises flat portions 12 lying in the same plane and a plurality of intermediate upright raised ribs 14 and a pair of lateral raised ribs 15 all of which project in the same direction from the plane of the flat portions 12.

The raised ribs 14 and 15 are vertically disposed with a raised rib 15 at a first and a second lateral edge 1 5a and 1 sub, respectively, ofthe panel member 11 and further raised ribs 14 intermediately located between the first and second lateral edges 1 spa and 1 Sb. The flat portions 12 are disposed between adjacent raised ribs 14and 15. The raised ribs 14and 15areformed by deformation ofthe panel member 11, in known manner. The vertically disposed raised ribs 14 and 15 produce a vertical rigidity in the panel member 11 whilst allowing an amount of horizontal flexibility found to be suitable to allow erection of the storage tank 10ofthe present invention.

As is best shown in Figures 1 and 3 each panel member 11 comprises a plurality of raised ribs 14 and 15, such as 6 raised ribs 14 and 15. The raised ribs 14 are equally spaced and the lateral raised ribs 15 have a lesser spacing. The panel member 11 has a width P and the distance between adjacent raised ribs 14 is designated D2, D3 and D4 respectively.

Typicallytheratios Pud2, PD3 and PD4 of panel width to inter-ribdistances is inthe rangefrom 3.2:1 to 5:1, preferably in the range from 4:1 to 4.5:1, for example about 4.3:1.The lateral raised ribs 15 are spaced at distances of D1 and D5 from adjacent raised ribs 14.

Typically the ratio PDa of the panel width to inter-rib distance at the first lateral edge 1 5a is in the range from from 12.5:1 to 5:1, preferably in the rangefrom 11.5:1 to 10:1,forexample about 10.8:1. Also, the ratio 05 ofthe panel width to inter-rib distance at the second lateral edge 15b istypicallyinthe rangefrom 3.5:1 to 5:1, preferably in the rangefrom 4:1 to 5:for exampleabout4.7:1.

It is envisaged that each panel member 11 could be formed from a 1200mm wide, 2100mm long and 0.6mm thick sheet of metal. In such a case the distance D1 is about 100mm; D2, D3 and D4 are about 250mm and D5 is about 230mm.

Figure 4 shows a cross section of one ofthe raised ribs 14or 15 of Figure 3. The size ofthe raised ribs l4or 15 suitable to form the tank 10 of the present invention is dependent upon the volume and the height ofthe tank. For example, a larger raised rib 14 or 15 may be needed to suit a tank of greatervolume and height than that considered herein. Although, it is understood thatthe strength ofthe endless wall may be increased by other means, as described hereinafter.

Each raised rib 14 or 15 has a length L, a width W, crest length C, a slope width S, a slope angle B, a thicknessTand a curve radius.

Forthe particular size panel member 11 described immediately hereinbefore the raised ribs 14 and 15 may have the following characteristics; the length L is about 35m m, th e width W is about 20mm, the crest length C is about 15mm, the slope width S is about 1 Omm, the slope angle P is about 26.6 ; the thicknessT is about 0.6mm and the curve radius is in the approximate range of 5 and 7mm.

It is envisaged that a panel member 11 of dimension other than that described hereinabove could use a different number of raised ribs 14 and 15 of different characteristics.

The raised ribs 15 of two adjacent panel members 11 are intended to overlap in use.

In particulara raised rib 1 5 of the first edge 15a of one panel member 11 is intended to cup, in use, into a raised rib 15 of the second edge 15b of an adjacent panel member 11.

It is envisaged that a panel member 11 having a different arrangement of raised ribs 14 and 15 could be used such that more than one raised rib 14 and 15 of adjacent panel members 11 overlap.

The panel members 11 also comprise a loop means comprising loops 16 extending from the flat portions 12 and projecting in a direction opposite to that of the raised ribs 14 and 15. The loops 16 are formed by punching two equally sized parallel slits in a flat portion 12. The material between the slits is then deformed awayfrom the flat portion 12 in a direction opposite to the raised ribs 14 and 15to form a loop 16 of material.

The panel members 11 each comprise a plurality of such loops 16, such as 12 loops 16, arranged toward the lateral edges 15a and 15b. The loops 16 are arranged so that half are adjacent one lateral edge 15a or 15b and half adjacent the other, with corresponding loops 16 being at the same height upon the panel member 11. Conveniently, the loops 16 are arranged in respective substantially vertical rows adjacent each lateral edge 15a and 15b.

The loops 16 are arranged to receive, in use, a plurality of support straps 17 as shown in Figure 5. The support straps 17 are formed of elongated flexible flat metal straps having holes 17a in each end thereof, as shown in Figure 6.

Each support strap 17 is, in use, threaded through each ofthe horizontally corresponding loops 16, as shown in FigureS. It is intended thatthe support straps 17 be of such length as to enable them to be threaded through loops 16 of more than one panel member 11, such as a bank of3 panel members 11.

Thus, the straps 17 align and retain, in side by side overlapped manner, a number of panel members 11, such as 3 panel members 11.

Individual banks of panel members 11 are con nected together by first overlapping their adjacent outer lateral edges 1 5a and 1 5b and secu ring co rres- pondingstraps 17 with bolt assemblies 18 arranged through the holes 17a of overlapping straps 17.

Any number of panel members 11 may be con nected in this mannerto form an endless wall storage tank 10. As is particularly shown in Figure 2 the support straps 17 are not equally spaced over the height ofthe panel member 11. It has been found that an equal spacing ofthe support straps 17 results in an unequal distribution of load thereon imparted by an outwardforce due to the contents oftank 10. In particular it has been found thatfor a tank 10 comprising 6 support straps 17 equally spaced up the panel members 11 a large force acts against the second lowest supportstrap from the bottom of the tank (Figure 5). The othersupportstraps then have progressively less load the higher up the tank 10 they are situated.

It is preferred to maintain substantially equal load on each ofthe support straps 17. To accomplish substantially equal supportstrap loading more closely spaced straps 17 are required toward the lower end of the tank 10. Figure 2 shows an arrangement for 6 support straps 17to achieve substantially equal distribution of load overthefoursupport straps 17 located within the uppermost and lowermostsupport straps 17.

In the arrangement of Figure 2 the uppermost and lowermost support straps 17 have substantially less load than the remaining support straps 17.

The height of the panel member 11 is designated H and the distance between adjacent support straps 17 is designated H1, H2, H3, H4, H5 and H6. The distance between the uppermost strap 17 and an uppermost edge of the panel member 11 is designated as H7.

Typicallythe ratio ofthe panel heightto the distance between adjacent support straps 17 is about 21 for HHa, about9.2:lfor HH2, about7.7:lfor HH3 about6.2:1 for 4, about4.1 :1 for HH5, about4.1 :1 for HHS, and about15.6:1 for 7.

Fora panel member height H of 2100mm the support straps 17 are typically spaced such that H1 is about 100mum, H2 is about 227mm, H3 is about 273mm, H4 is about 338mm, H5 is about 51 Omm, H6 is about 517mm and H7 is about 135mm.

It is envisaged thatthe ratio Wi be in the range of 14:1 to 21:1. That is, it is envisaged that the height H1 ofthe lowest strap 17 could be altered by up to about 50mm.

The preferred location ofthesupportstraps 17 is mainly dependent upon the height ofthe panel members 1 1.Thus, the ratios may be applied to produce a tank 10 of a different height with substantially even loading on the support straps 17. However, it is to be understood that a scaling ofthe height and strap location of the tank 10 will result in corresponding scaling ofthe load bearing capabilityofthetank 10.

For example, an increase in the height of the tank 10 will iead to a corresponding decrease in the load bearing capability ofthe straps 17 and the tank 10.

In orderto enablethetank lotto store liquids, solids or powders of different densities it is generally only necessaryto alterthe support straps 17. For example, to enable the tank to store a dense liquid such as oil relatively stronger support straps 17 may be used than would be necessary in the storage of water or grain such as wheat.

When the tank 10 is used to store liquids the load on the support straps 17 is principally dependent on the head of water and the diameterofthetank 10. It isto be understood that the capacity of thetank 10 is also dependent on wind loading and wave formation (for stored liquids and bearing and shearforces on the soil and the like.

ltfollowsthatthe load bearing capability of the tank 10 may be increased by increasing the size, gauge and yield strength of the support straps 17,the panel member 11 and the dimensional parameter of the tank 10 described herein.

When the tank 10 is used to store solids or powders the load onthesupportstraps l7isprincipally dependent on the height of the solids or powders and the angle at which it will stack. That is, solids and powders can be substantially selfsupporting except for a periphery in which the solids or powders tend to slide underforce of gravity. The angle of slope ofthe solids or powders at which no sliding occurs is called the stack angle.

The load due to solids or powders on the support straps 17 is onlysecondarilydependenton the diameter ofthetank 10. Therefore, the capacity ofthe tank with respectto solids and powdersfora given strength of support straps is substantially dependent on the height of the solids and powders. Thus,to increase the capacity ofthe tank lOin respect of storage of solids and powders it is generally necessary only to increase the diameter ofthe tank 10 whilst maintaining the height of the tank 10 substantially constant. An important point to note in regard to the storage of solids and powders is that the load on the support straps 17 may not be constant.For example, where a tank 10 containing grain has some ofthe grain removed via an outlet located at the side ofthetank 10 the load on the support straps 17 located opposite the outlet may be substantially greaterthan that near the outlet. Such non uniform loading of the tank 10 must be considered in determining the load capability of the tank. Thus, the actual capacity ofthe tank in respect of solids and powders is also dependent on the likely non uniform loading caused bythestacking effect of its contents. It is to be understood that an even distribution of support straps 17 could be used. In such a case it is also understood that an evenly distributed arrangement of support straps 17 generally results in a lower load bearing capacity ofthe tank 10.Itfollows from this that relatively smallertanks 10 could comprise such an arrangement ofsupportstraps 17.

The storage tank 10, in use, is intended to have a liner 20 formed of a resilient material such as a polyvinyl chloride plastics material orthe like, as shown in Figures 2 and 5. Preferably, the liner 20 has resistance to U.V. light. The liner 20 is intended to be located inside the storage tank 10 and secured to the top of each panel member 11 by a securing means 22.

The securing means 22 comprises a capping angle 24 and a plurality of securing plates 26. The capping angle 24 is laid, in use, on the wall ofthe tank 10 on top ofthe liner 20. The capping angle 24 is secured to the uppermost one ofthesupportstraps l7bythe securing plates 26 and thus secures the liner 20 in place. The capping angle 24 also provides an amount of rigidityto the upper reaches ofthe tank 10. Such rigidity may be necessary in situations when the tank lOis substantially empty.

It is envisaged that patches may be required to coverthe inside of the storage tank 10, at locations corresponding to the loops 16, to protect the liner 20.

The storagetank 10 may have a cover (not shown) positioned atop.

The cover may coneniently be formed of material similartothe liner 20.

The cover may be arranged so that substantially all of its area is in close proximity with a stored liquid. It is envisaged that a flotation means (not shown) would be useful to communicate the liquid level to the cover.

Thus, the cover could be maintained substantially at the same level as the liquid.

In thiswaythe volume of air between thecover22 and the liquid may be maintained as small as possible.

It is desired to reduce the volume of airabovethe ofairabove the liquid to reduce the growth of algae and the like in the liquid. It is further envisaged that the storage tank 10 could comprise a roof means (not shown) to seal its contents from the outside environment. The roof means could also be sealed to the capping angle 24 to renderthetank 10substantiallyairtight.

It is preferred that, in use, the raised ribs 14 and 15 of the panel member 11 be disposed inwardly ofthe storage tank 10. It has been found that such an arrangement has preferable features compared to an arrangement with outwardly disposed ribs. In particular, it results in a more evenly distributed outward force on the panel members 11 and on the support straps 17. Such even distribution of force occurs since the support straps 17 contact the flat portions 12 ofthe panel members 11.

If the raised ribs 14 and 15 extend outwardly of the storage tank 10 the support straps 17 may be drawn through slots 16 in the raised ribs 14 and 15. Such an arrangement is not preferred since the plurality of slots 16 result in much friction in drawing the straps 17 therethrough. Also, in use, such an arrangement would result in deformation of flat portions 12 of the panel members 11 under the force of the contents of the tank 10.

Also, the preferred arrangement yields less stretch on the liner 20 about the raised ribs 14 and 1 Swhen the storage tank 10 has a store of liquid or solids or powders, such as water, grain or cement powder. That is, since the raised ribs 14 extend inwardly of the storage tank 10 the liner 20 is not forced into the raised ribs 14and 15 and so is notsubjectedto as much stretching as otherwise may occur. In use, an unassembled tank 10 is taken to a desired location and a number of panel members 11, such as 3 panel members 11, are laid in side by side arrangement with adjacent raised ribs 15 overlapped.

Then the support straps 17 are threaded through horizontally corresponding loops 16 of the overlapped panel members 11. Once the straps 17 are threaded the bank of panel members 11 are stood up and the bank bent to a desired amount of curvature. The amount ofcurvature desired is that which will ultimately yield a storage tank 10 of desired radius once a plurality of banks are secured together.

The banks are secured together by the bolt assemblies 18, shown in Figure 5, engaged with the holes 1 7a (Figure 6) of overlapping straps 17.

When the wall ofthe storage tank 10its completed, by the bolting together ofthefirst and the last panel members 11, the liner 20 and the roof may be placed in and on the storage tank 10.

It has been found that a support base is not essential in supporting the apparatus ofthe present invention, as the outward force ofthe stored substance is usually sufficientto preventsinkage ofthe panel members 11 into the ground. However, it is to be understood that a lip may beformed on the lower edge ofthe panel members 11 to further assist in the vertical support of the storage tank 10.

Preferably, the storage tank 10 is to be erected on a bed of dense sand 40 spread over a permeable underlay42 on top of the ground 44 as shown in Figures 2 and 5. It has been found thatsinkage ofthe panel member 11 is least likely when erected on a dense sand 40 ratherthan a clay based soil 44. Further, the permeable underlay 42 is preferred to reduce the occurrence of the dense sand 40 combining with the lower soil 44. Also, if the liner 20 develops a leak the underlay 42 will allow a liquid stored in the tank 10 to flow awaysubstantiallywithout errosion of the dense sand 40.

If an underlay 42 is not used it is predicted that a leak could cause considerable errosion of the supporting sand 40 and ground44andcould result in the collapse ofthetank 10.

If the storage volume ofthe storage tank 10 is to be increased or reduced one may effect such achange by respectively adding or removing panel members 11 or banks of panel members 11 1 and support straps 17.

It is envisaged thatthetank 10 of the present invention could comprise inlet means and outlet means for entry and exit ofthe substances stored therein.

Also, it is envisaged thatthe tank 10 could be adapted, with the addition of doors and the like and the deletion ofthe liner20, as a dwelling. The dwelling could require some form of insulation and/orventialation. Modifications and variations such as would be apparent to a skilled addressee are deemed within the scope of the present invention. For example, panel members 11 of a shape otherthan that described hereinabove could be used provided the straps 17 could still retain the panel members 11 secured in side by side alignment.

Further,the plurality of panels 11 could be replaced by a single sheet of ribbed material curved around so that its ends overlap to form the endless wall ofthe storage tank 10. Also, it is envisaged that the lower reaches ofthe storage tank 10 would be coated with a corrosion resistant substance such as polyurethane.

Also, panel members 11 of a width other than 1200mm could be used and thus may require ratios other than those mentioned hereinabove.

Claims (23)

1. Astoragetankcomprising an endlesswall formed of a plurality of overlapping panel members with atleastone endless support strap extending substantially horizontallyaround the endless wall, wherein each panel member comprises a loop having an endlesssupportstrap extendingtherethrough.

2. Astoragetankaccording to claim 1,characte rised in that each panel member comprises a plurality offlat portions situated in the same plane and being located between spaced upright ribs projecting in the same direction from the plane of the flat portions.

3. A storage tank according to claim 2, characte rised in that each panel member comprises a plurality of loops arranged with some ofthe loops located adjacent afirst lateral edge ofthe panel member and with otherofthe loops located adjacent a second opposite lateral edge, pairs of loops located atthe opposite lateral edges being, in use, at substantially the same height and having an endless support strap extending therethrough.

4. Astoragetank according to claim 2 or3, characterised in thatthe loops extend from the flat portions and project in a direction opposite to that of the upright raised ribs.

5. A storage tank according to any one of claims 2 to 4, characterised in that each panel member is arranged with the upright raised ribs extending inwardly ofthe storage tank and the loops extending outwardly of the storage tank.

6. A storagetankaccording to any one of claims 2 to 5, characterised in that the loops are integrally formed with the panel members.

7. A storage tank according to any one of claims 2 to 6,characterised in thatthe loops and thus the support straps are arranged at non-uniform spacings up the panel member.

8. Astoragetank according to anyone of claims2 to 7, characterised in that the height of the panel member is H and the distance from a lower edge of the panel member and a centre of a lowermost loop is H1 and the lowermost loop is situated such thatthe ratio H isintherangeof14:1to21:1.

9. A storagetankaccording to claim 8, characte rised in thatthe distance from the centre of the lowermost loop to the centre of a second lowest loop is H2 and the second lowest loop is situated such that the ratio H isabout9.2:1.

10. Astoragetank according to claim 8 or 9, characterised in thatthe distance from the centre of the second lowest loop to the centre of a third lowest loop is H3 and the third lowest loop is situated such thattheratio H3 isabout7.7:1.

11. A storage tank according to any one of claims 8 to 10, characterised in thatthe distance from the centre ofthe third lowest loop to the centre of a fourth lowest loop is H4 and the fourth lowest loop is situated such thatthe ratio HH4 iS about 6.2:1.

12. A storage tank according to any one of claims 8 to 11, characterised in thatthe distancefrom the centre of the fourth lowest loop to the centre of a fifth lowest loop is H5 and thefifth lowest loop issituated suchthattheratio H isabout4.1:1.

13. Astoragetank according to any one of claims 8 to 12, characterised in thatthe distancefrom the centre ofthe fifth lowest loop to the centre of a sixth loop is H6 and the sixth loop is situated such that the ratio -Hs isabout4.1:1.

14. A storage tank according to any one of claims 8 to 13,characterised in that the distance from the centre of a highest loop to an uppermost edge of the panel member is H7 and the heightofthe panel member is such thatthe ratio -H7 is about 15.6:1.

15. Astoragetankaccording to any one ofthe preceding claims, characterised in that it comprises a linerformed of a resilient material and disposed inside the endlesswall and secured to an upper edge thereof.

16. Astoragetankaccording to any one of the preceding claims, characterised in that it comprises inlet and outlet means to provide for entry and exit of material to be stored therein.

17. Astoragetankaccording to any one ofthe preceding claims, characterised in that it comprises a roof means.

18. A storage tank according to any one ofthe preceding claims, characterised in that it is adapted as a dwelling andcomprisesa roof means, afloor means, a door means and ventilation means.

19. A substantially flat panel member characterised in that it comprises a plurality of upright raised ribs and an integral loop arranged to receive, in use, a substantially horizontal support strap.

20. A substantially flat panel member according to Claim 19, characterised in thatthe upright ribs project in the same direction from the plane ofthe panel member.

21. A substantially flat panel member according to Claim 20, characterised in that the loops project in an opposite direction to the upright raised ribs.

22. A storage tank substantially as hereinbefore described with reference to and as illustrated in the drawings.

23. A panel member substantially as hereinbefore described with reference to and as illustrated in Figures 1 to 4 of the drawings.