Note: Descriptions are shown in the official language in which they were submitted.
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=
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
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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 A'-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:
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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 'I' beam, also known as an
'H' 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.
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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
=to 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
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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
5 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 1.2 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.
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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.
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BRIEF DESCRIPTION OF THE DRAWINGS
By way 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
11 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.
=
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Figure 2 illustrates a closer view of a portion of the tank around the
region labelled 'A', 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 top: 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
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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 10, 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
o set of cables, is provided for each aperture height, with each cable, or
set of
cables, traversing the perimeter of the tank 10. 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
/5 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
20 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
25 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
30 adjacent stressing support members 11'. The vertically offset apertures
18'
are utilised to tension and secure each cable.
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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
5 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
/o 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 LULDPE liner, 0.75mm Geofiex, 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 'Li' 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.
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Once all the panels 12 are in place in their respective support members
11, 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
/o 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
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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
= 5 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.
