EP2699494A1

EP2699494A1 - Storage tank

Info

Publication number: EP2699494A1
Application number: EP12773574.4A
Authority: EP
Inventors: Kieron JEFFRIES; Shaun Edward Barry
Original assignee: Concept Environmental Services Pty Ltd
Current assignee: Concept Environmental Services Pty Ltd
Priority date: 2011-04-20
Filing date: 2012-04-19
Publication date: 2014-02-26
Also published as: AU2012245072A1; EP2699494A4; WO2012142661A1; CA2833447A1; US20140144916A1; AU2012245072B2

Abstract

A storage tank (10) for storing a fluid, such as water, having a wall defined by a plurality of panels (12) which are retained by opposed side edges between adjacent support members (11). The support members have a base portion (13) and a support portion (15) and are free-standing on the base portion (13) on an earthen floor allowing the tank (10) to be constructed at sites without concrete foundations such as a concrete pad or ring. Preferably all that is required prior to construction of the tank (10) is for the site to be graded (if necessary). The tank also has a liner (20) that lines the interior surfaces of the wall and the floor.

Description

STORAGE TANK

FIELD OF THE INVENTION

The invention relates to tanks. In particular, the invention relates, but is not limited, to free standing fluid, preferably water, storage tanks that are erected at site without a concrete foundation.

BACKGROUND TO THE INVENTION

Reference to background art herein is not to be construed as an admission that such art constitutes common general knowledge in Australia or elsewhere.

Tanks of various shapes and sizes are known for storing fluids, in particular liquids, such as water. Such tanks vary in size tremendously from, for example, a personal water storage tank for drinking or irrigation purposes to industrial or commercial storage tanks. Small tanks are relatively easy to assemble and can often be moulded as a single piece (e.g. 1-5KL water storage tanks). However, as tank sizes increase it becomes increasingly more difficult to construct a sealed tank for storing fluid.

One of the issues with constructing large tanks is in transporting and building the tank, particularly for remote locations. For example, in mining, oil, and gas applications, water is a common by-product which may be processed and/or stored in tanks, or reservoirs, or the like. Furthermore, primary extraction fluids, such as oil or condensate, are also often stored in holding tanks. The storage of these liquids in the tanks may be long term or temporary. In any event, often the well or mine site is in a remote location with limited infrastructure and building a tank requires significant preparation.

Typically a site for a tank requires earth working, grading, and a concrete pad or footing. In one tank design, an annular concrete footing is provided which tracks the perimeter of the tank. The tank walls then extend off the pad or footing . Considerable time and expense is taken to prepare the site for tank construction. Furthermore, often tanks are, or have to be, decommissioned at the end of their use or life. This includes digging up and removing the concrete pad or footing which is again time consuming and costly. There may also be adverse environmental impacts from utilising, and subsequently disposing of, the concrete pad or footing.

Large tanks also often suffer from hoop stress and, when empty, wind loading. In order to avoid these variables tanks may be designed of a limited size. This is clearly undesirable if a larger tank is required, usually necessitating multiple tanks where one larger tank may have been sufficient.

Furthermore, the walls of the tank may need to be reinforced with an external structure. For example, the walls of the tank may be reinforced with a frame. Such a frame typically has support members which extend radially outwards from the tank walls. In one tank design, the support members are steel Ά'-frame members. Disadvantageously, such supporting framework requires additional space around the tank walls. As the support members need to be provided with suitable support, the concrete pad or footing also needs to be large enough to extend to at least the outer edge of the framework, further increasing costs and environmental impact of the tank.

OBJECT OF THE INVENTION

It is an aim of this invention to provide a storage tank which overcomes or ameliorates one or more of the disadvantages or problems described above, or which at least provides a useful alternative.

Other preferred objects of the present invention will become apparent from the following description. SUMMARY OF INVENTION

According to a first aspect of the invention, there is provided a storage tank for storing a fluid, the storage tank comprising: a wall defined by a plurality of panels and a plurality of support members, wherein each of the support members has a base portion and a support portion, and each panel is retained, by opposed side edges, between respective support portions.

The tank preferably further comprises a liner. The liner is preferably located on at least an inner side of the wall. The liner preferably lines an inner surface of the tank defined by the inner surface of the wall and a floor. The floor preferably includes a surface upon which the support members are placed. The surface may be earthen, preferably graded. Preferably the tank, and in particular the support members, do not require, or even include, a concrete surface or concrete foundations for support.

The wall is preferably generally circular, and defines the perimeter and, together with the liner, the storage volume of the tank. Preferably the wall defines a low, wide tank.

The panels are preferably planar members and are preferably rectangular. The panels may be concrete, preferably reinforced, and even more preferably pre-stressed. The concrete may be reinforced with a mesh, preferably with SL82 reinforcing mesh, and/or a stressing cable, preferably a plurality of strands, even more preferably three strands of 10-20mm stressing cable. In a preferred form, the stressing cable is between 12mm and 16mm, preferably 12.7mm or 15mm.

The support members are preferably free standing on the base portion on a surface. The support portion is preferably an Ύ beam, also known as an Ή' beam, but hereinafter referred to as an I-beam. The support portion is preferably welded to the base portion. The side edges of the panels are preferably retained between two flange portions of the I-beam. Respective panels retained by a support portion are preferably separated by a web portion between the two flange portions of the I-beam; an inner flange, on the inside of the wall, and an outer flange, on the outside of the wall. Each panel is preferably slotted in between the two flange portions of the I-beam at each edge. The wall is preferably constructed of alternating support members and panels, and is preferably free standing and supported vertically by the base portion of the support members. The support portion is preferably substantially perpendicular to the base portion. The base portion is preferably planar and/or rectangular. In a preferred form, the base portion is rectangular with a longitudinal axis substantially parallel, or the same as, the axis of the span of the web portion between the flange portions of the I-beam.

The tank may further comprise a reinforcement assembly which, preferably, does not increase the footprint of the tank. The reinforcing assembly preferably comprises at least one cable. Alternatively, or even in addition, the reinforcing assembly may comprise at least one reinforcement strap. The at least one cable preferably extends around at least a portion of the perimeter of the wall. The cable may extend around the entire perimeter of the wall or a plurality of cables may extend around portions of the perimeter of the wall. Preferably if a plurality of cables extend around portions of the perimeter of the wall, the cables collectively extend around the entire perimeter of the wall.

Preferably, at least some of the support members have an aperture in the support portion for receiving the reinforcement assembly. Preferably the aperture is in the web portion of the I-beam. Even more preferably, the aperture is located on an outer side of the web portion of the I-beam adjacent the outer flange. The apertures are preferably round and/or oval.

In a preferred form, each support member has an aperture in the support portion which receives a stressing cable. In an even more preferred form, each support member has three spaced apart apertures, each for receiving a respective stressing cable. Preferably one of the apertures is near the top of the support portion, one near the bottom of the support portion, and one somewhere in between. In a preferred form, the middle aperture is closer to the bottom aperture than the top aperture.

The support members may or may not be identical. Preferably there are two types of support members: a standard support member and a stressing support member. Preferably the majority of support members are standard support members. In a preferred form, a stressing support member is provided for every quarter of a circular tank.

The stressing support member preferably has at least one aperture that is vertically offset from a corresponding aperture on the standard support members. Preferably the vertically offset aperture is higher than the corresponding aperture on the standard support members. Preferably the stressing support member has a vertically offset aperture corresponding to each of the apertures on the standard support member. The stressing support member may also have one or more apertures corresponding directly to the apertures on the standard support member (i.e. not offset). One or more of the apertures of the stressing support member may be reinforced.

The tank may further comprise a leak detection system. The leak detection system may comprise a leak detection liner. The leak detection liner is preferably adjacent, and external to, a primary liner (described previously). The leak detection liner preferably has an outlet in fluid communication with a conduit. The leak detection liner and/or outlet preferably comprise a sump. The conduit preferably extends from the fluid detection liner outlet to a leak detection location outside of the tank wall.

In use, any fluid exiting the conduit at the leak detection location indicates that there is a leak in at least the primary liner. An electronic sensor may also be utilised to detect a leak. Preferably, a transmission means is coupled to the electronic sensor such that notification of a leak can be transmitted to a receiver. Once the receiver detects such a transmission, a warning may be issued.

The wall may be a circular wall of 10m to 200m in diameter and may be 1m to 5m high. Preferably, the wall is a circular wall 20m to 80m in diameter and 1m to 2m high, even more preferably 40m to 70m in diameter and .2 to 1.8m high. In a preferred form, the wall is 60m in diameter and 1.4m high. Of course, it will be appreciated to a person skilled in the art that other sizes outside these sizes/ranges may be achievable. According to a second aspect of the invention, there is provided a method of assembling a tank on a site, the method comprising the steps of: arranging a plurality of support members around the site; and mounting a panel between adjacent pairs of support members to form a continuous wall that defines the perimeter of the tank.

Preferably, the site is graded prior to arranging the support members. Preferably the support members have a base, are self standing, and do not require a concrete pad or footing to be laid first.

Preferably the method further comprises applying a reinforcement assembly. Preferably the step of applying a reinforcement assembly comprises running a tensioning line around the perimeter of the wall. Even more preferably, the step comprises running a stressing cable through apertures in the support members. The cable is preferably then tensioned and secured. The cable may be tensioned and secured using cable wedges.

The step of arranging a plurality of support members may comprise utilising a level and/or measuring device, preferably a laser level and laser measuring device. Preferably the level and measuring device are placed adjacent a centre point for the tank. The level and measuring device are preferably utilised to determine support member and/or panel locations on the site.

Preferably the method further comprises the step of installing at least one liner to an inner surface of the wall and a floor, the floor preferably being the site surface (e.g. the graded site). Preferably the method further comprises constructing a leak detection system. Preferably this step comprises grading the site for leak detection, and installing a leak detection liner underneath the primary liner. The leak detection liner preferably has an outlet arranged to fluidly communication with a conduit, the conduit preferably being installed to extend from the outlet of the leak detection layer, under the wall, to a leak detection location outside the wall.

Further features and advantages of the present invention will become apparent from the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

Byway of example only, preferred embodiments of the invention will be described more fully hereinafter with reference to the accompanying figures, wherein:

Figure 1 illustrates a plan view of a tank according to an embodiment of the invention.

Figure 2 illustrates a close up view of a portion of the tank illustrated in figure 1.

Figure 3 illustrates a close up view of a single support structure of the tank illustrated in figures 1 and 2.

Figure 4 illustrates a side elevation view of a standard support structure according to an embodiment of the invention.

Figure 5 illustrates a side elevation view of a stressing support structure according to an embodiment of the invention.

Figure 6 illustrates a plan view of the stressing support structure illustrated in figure 5.

Figure 7 illustrates a cross sectional view of a panel of the tank showing a liner.

DETAILED DESCRIPTION OF THE DRAWINGS

Figure 1 illustrates a plan view of a tank 10 according to an embodiment of the invention. The tank 10 of the illustrated embodiment is generally circular, having a continuous wall made up of 81 support members 1 and 80 panels 12 (in the interests of clarity, only a few select support members 11 and panels 12 have been pointed to). As will be appreciated the number of support members and panels may be altered to suit different requirements. Figure 2 illustrates a closer view of a portion of the tank around the region labelled Ά', where the support members 11 and panels 12 can be more seen more clearly.

Figure 3 shows the region labelled 'A' in figures 1 and 2 in more detail, clearly showing two panels 12 joined, and retained, by a support member 11. The support member 11 has a base portion 13 and a support portion 14. The support portion is an I-beam member, having an inner flange 15 and an outer flange 16 separated by a web 17. As illustrated in figure 4, which shows a side elevation view of a single support member 11 without any panels 12, the I-beam support portion 14 is elongate, extending substantially perpendicularly from the base portion 13.

The base 13 is a substantially planar rectangular portion of the support member 11. Longitudinal axis of the base is aligned with the span of the web 17 between the flange portions 15, 16 of the I-beam. In use, the longitudinal axis of the base is generally perpendicular to the plane of the panels 12 that the support member 14 is holding. This provides support to the support member 11 from falling perpendicularly to the plane of the panels 12; the support member being supported laterally, in use, by the panels 12 on either side of it. In a preferred embodiment, the support member is 1.2m high with a 150 UC 30 I-beam and a base plate of approximately 757x250x16mm.

The panels 12 are rectangular planar panels made of concrete. The concrete is pre-stressed with a reinforcing element 12, such as mesh or, in a preferred embodiment, 12.7mm or 15mm stressing. In a preferred embodiment the concrete panels are 2.4m long, 1.4m high, and 80mm thick. Preferably the panel has a concrete strength of at least 40MPA.

As illustrated in figure 4, the support portion 14 of the support member 11 has three apertures 18. The three apertures are spaced apart with one near the topi one near the bottom, and one in between the other two. The middle aperture is closer to the bottom aperture than the top aperture. The apertures 18 are located in the web 17 of the I-beam, and are for receiving a stressing cable (not shown) therethrough. The top two sets of apertures are round, and the bottom aperture is oval. In an embodiment, all of the apertures are oval. This allows different sized cables to be used in the same support members 11 , which is particularly important for reuse of support members 11 from one application to another (e.g. different sized tanks). For example, for a 40m diameter tank a 12.7mm cable may be used, and for a 60m diameter tank a stronger 15mm cable may be used.

A single cable may traverse the perimeter of the wall of the tank 1 , but in a preferred embodiment a set of four smaller cables, each traversing an equal portion of the wall of the tank 10, may be utilised. A separate cable, or set of cables, is provided for each aperture height, with each cable, or set of cables, traversing the perimeter of the tank 0. Each cable is tensioned and secured using cable, wedges (not shown). The cables provide additional reinforcement to the tank wall, without substantially increasing the footprint of the tank (e.g. as occurs when utilising a support framework which extend beyond the outer wall of the tank). In a preferred embodiment, the cable is a 12.7mm or 15mm super grade stress relieved low relaxation strand cable having a breaking strain of approximately 250Kn.

Figure 5 illustrates a different type of support member in the form of a stressing support member 11'. The stressing support member 11 ' is similar to the standard support members 11 , but is of a slightly heavier constructions as the I-beam support portion is heavier, in a preferred embodiment 150 UC 37. Other than the I-beam support portion, the dimensions of the stressing support member are the same.

The stressing support member 11' has two sets of apertures, the standard apertures 18 and vertically offset apertures 18' . The vertically offset apertures 18' are adjacent, but vertically higher than, the standard apertures 18. The vertically offset apertures 18' are located in tabs 19 which extend from the outer flange 16. Preferably a plurality of stressing cables are provided for each aperture height, with each stressing cable going between adjacent stressing support members 11'. The vertically offset apertures 18' are utilised to tension and secure each cable. Figure 7 illustrates a cross section through a panel 12 of the tank 10. Illustrated in figure 7 is a liner 20. The liner 20 extends from a floor level 21 to up, and over, the panel 12. The liner 20 lines the entire inner surface of the tank 10 to seal the tank. A further liner (not shown) adjacent to the first line may also be utilised for leak detection.

The leak detection liner is located adjacent the standard liner 20 but has an outlet in fluid communication with a conduit. The conduit extends from the outlet, which is usually under the tank, below the wall of the tank to an external location, if liquid is found coming out of the conduit, it indicates that there is a leak in the liner, and that liquid is escaping the tank. The leak detection liner may be a 200 micron polyethylene (pe) liner, and the primary liner may be a 0.75mm LL/LDPE liner, 0.75mm Geoflex, or a Thermoplastic Polyolefin (TPO). The primary liner 12 and the leak detection liner may be adjacent to, or separated by, a geotextile and/or geo-net,

To construct a tank 10 at a remote site, the site is first graded, including creating a pad for the leak detection system. The support members 11 are then transported to site and unloaded around the site. A laser level and laser measuring device are placed above a centre point for the tank 10. The support members 11 are then arranged around the centrepoint, with the laser measuring devices ensuring they are located the correct distance from the centre. As the panels 12 have a known width, the spacing between the support members 11 can be determined. This may also be done using some form of panel template.

The base plate 13 of each support member 11 allows the support member 11 to sit upright on a ground surface without the need for a concrete pad or footing. The panels 12 are then lowered into 'U' channels formed by side portions of the flanges 15, 16, and the web 17. Wedging blocks (not shown) may be utilised, if necessary, to prevent movement of a panel 12 in a U-channel of an I-beam during installation. A conduit is also placed under one of the panels for the leak detection system. Once all the panels 12 are in place in their respective support members 1 , a stressing cable is spooled off a reel and fed through the apertures 18 of the support portion 14 of the support members 11 between stressing support members 11'. Once the cable extends between two stressing support members 11' the cable is tensioned and secured using cable wedges. A separate cable is installed for each set of aperture height (i.e. there are three cables, one through each of the three apertures 18 illustrated in the figures). Multiple cables are secured until the cables traverse the perimeter of the wall formed by the panels 12 retained by the support members 11. Finally, the liners are installed and, once installed, the tank is ready for use.

Advantageously, the tank 10 of the present invention can be readily assembled at a site without the need for a concrete pad or footing. Furthermore, the footprint of the tank 10 is not increased to allow for an external support framework, such as A-frame members. These reduce the environmental impact of the tank, and time and money when decommissioning. Furthermore, not require a concrete pad or footing to set reduces the time taken to install the tank 10. All of the structural components of the tank are reusable, and a tank can be disassembled and reassembled at another site as may be required. The support members 11 and panels 12 also have enough weight to make them resistant to high winds even when the tank is empty.

Compared with traditional liquid holding reservoirs, the tank 10 of the present invention also has a low visual impact and does not require work at heights, due to its low walls. The modular nature of the design also allows tanks of different shapes and sizes to be constructed, depending on the site and requirements.

Reference herein to a wall is intended to refer to a continuous wall, but is not intended to exclude walls with corners, or the like, such as a rectangular or square wall.

In this specification, adjectives such as first and second, left and right, top and bottom, and the like may be used solely to distinguish one element or action from another element or action without necessarily requiring or implying any actual such relationship or order. Where the context permits, reference to an integer or a component or step (or the like) is not to be interpreted as being limited to only one of that integer, component, or step, but rather could be one or more of that integer, component, or step etc.

The above description of various embodiments of the present invention is provided for purposes of description to one of ordinary skill in the related art. It is not intended to be exhaustive or to limit the invention to a single disclosed embodiment. As mentioned above, numerous alternatives and variations to the present invention will be apparent to those skilled in the art of the above teaching. Accordingly, while some alternative embodiments have been discussed specifically, other embodiments will be apparent or relatively easily developed by those of ordinary skill in the art. The invention is intended to embrace all alternatives, modifications, and variations of the present invention that have been discussed herein, and other embodiments that fall within the spirit and scope of the above described invention.

In this specification, the terms 'comprises', 'comprising', 'includes', 'including', or similar terms are intended to mean a non-exclusive inclusion, such that a method, system or apparatus that comprises a list of elements does not include those elements solely, but may well include other elements not listed.

Claims

The claims defining the invention are as follows:

1. A storage tank for storing a fluid, the storage tank comprising: a wall defined by a plurality of panels and a plurality of support members, wherein each of the support members has a base portion and a support portion, and each panel is retained by opposed side edges between respective support portions.

2. A storage tank according to claim 1 , further comprising a liner located on an inner side of the wall.

3. A storage tank according to claim 2, wherein the liner lines an inner surface of the tank defined by an inner surface of the wall and a floor of the tank.

4. A storage tank according to claim 3, wherein the floor of the tank is the surface upon which the support members are placed.

5. A storage tank according to claim 3 or 4, wherein the floor is earthen.

6. A storage tank according to any preceding claim wherein the base portion of the support members is planar and substantially perpendicular to a longitudinal axis of the support portion.

7. A storage tank according to any preceding claim wherein the support portion of the support member has an inner flange and an outer flange separated by a web portion.

8. A storage tank according to any preceding claim wherein the support portion of the support member is an I-beam welded to the base.

9. A storage tank according to any preceding claim wherein the panels are substantially planar concrete panels.

10. A storage tank according to claim 9 wherein the panels are prestressed reinforced concrete panels.

11. A storage tank according to any preceding claim further comprising a reinforcement assembly.

12. A storage tank according to claim 1 wherein the reinforcement assembly does not increase the footprint of the tank.

13. A storage tank according to claim 11 or 12 wherein the reinforcement assembly comprises one or more cables that extend around the wall of the tank.

14. A storage tank according to claim 13 wherein the support members have an aperture in the support portion to receive the one or more cables.

15. A storage tank according to any preceding claim wherein the tank does not require concrete foundations.

16. A method of assembling a tank on a site, the method comprising the steps of :

arranging a plurality of support members around the site; and mounting a panel between adjacent pairs of support members to form a continuous wall that defines the perimeter of the tank.

17. A method of assembling a tank on a site according to claim 16 further comprising the step of grading the site prior to arranging the plurality of support members.

18. A method of assembling a tank on a site according to claim 17 wherein the support members are self standing on the graded surface.

19. A method of assembling a tank on a site according to any one of claims 16 to 18 further comprising the step of applying a reinforcement assembly.

20. A method of assembling a tank on a site according to claim 19 wherein the step of applying a reinforcement assembly comprises running a tensioning line around the perimeter of the wall.

21. A method of assembling a tank on a site according to claim 20, wherein the step of running a tensioning line around the perimeter of the wall comprises running one or more cables through apertures in the support members.

22. A method of assembling a tank on a site according to claim 21 , further comprising the step of tensioning and securing the one or more cables with cable wedges.

23. A method of assembling a tank on a site according to any one of claims 16 to 22 further comprising the step of installing at least one liner to an inner surface of the wall and a floor of the tank.