Patent Description:
In some fields of technology, very large tanks are used for holding large amounts of liquid. One such technology is onshore fish farming. Within this field, often referred to as RAS technology (recirculating aquaculture system), fish is kept in tanks having a diameter of for instance <NUM> to <NUM> meters.

Some RAS systems use tanks made of concrete. Concrete is a well-known and proven material but has some disadvantages. For instance, once concrete tanks are built, they are costly to dismount. Furthermore, examples have shown that when filling such large tanks with water, the added weight may result in ground settling that makes the concrete crack. As an illustrational example, the water held by a fully filled square-shaped tank with <NUM> meter sides and a water depth of <NUM> meters will weigh <NUM> tonnes. Such amounts of mass demand a stable ground.

An alternative is to use tanks made of a fiber-reinforced material, typically GRP or FRP (glass fiber-reinforced plastic / fiber-reinforced plastic). At least in part due to the size of such tanks, such fish tanks are typically installed near the sea. Such a location enables transport of the tanks to the site in one large piece or in separate but large pieces.

Installing GRP or FRP tanks that are remote from the sea, such that ship transport is impossible, can however be problematic with known tanks. The size of such tank pieces is typically restricted to the capability of road trucks.

Another transport issue is the desire to transport such tanks in a compact state, i.e. in a manner where even large tanks can be transported with few and small-sized items. Typically, it would be desirable to transport the tanks in standard containers, of the type that can be carried by road trucks.

<CIT> discloses a modular structure for being at least partially submerged in water. The structure can be used for containing live fish, and is built by joining a plurality of modules into a complete structure.

According to the present invention, there is provided a fiber-reinforced plastic material aquaculture tank comprising side walls. The side walls comprise a plurality of horizontally oriented wall beams that are stacked vertically on top of each other. The respective wall beams have a first side plate and an oppositely arranged second side plate. The first and second side plates, respectively, comprise a vertical wall portion, wherein there is a horizontal distance between the vertical wall portions of the first and second side plates, respectively. Furthermore, the first and second plates are made of a fiber-reinforced plastic material. The side plates further comprise connection flanges that extend parallel to the horizontal extension of the wall beams. The connection flanges of the respective two oppositely arranged side plates curve towards each other. The connection flanges comprise bolt apertures and access apertures.

The fiber-reinforced plastic material can typically be GRP (glass-fiber reinforced plastic). However, other fiber-reinforced composite materials can also be used.

With the term aquaculture tank is meant water-holding tanks related to aquaculture, e.g. water-holding tanks with live fish, or tanks used for water treatment. A typical embodiment where the tank can be used for water treatment, is an RAS system (recirculating aquaculture system). In such systems, tanks according to the present invention may for instance be used as a settling tank or water treatment tank.

In some embodiments, the side plates can further comprise attachment flanges that are arranged vertically opposite of the connection flanges and which extend parallel to the horizontal extension of the wall beams. The attachment flanges of the respective two oppositely arranged side plates can curve towards each other.

By having access apertures in addition to the bolt apertures, one is able to access the bolts to connect one wall beam to the previously installed wall beam.

The connection flange and the attachment flange of the respective side plates may extend with a different horizontal extension crosswise to the longitudinal length of the side plates. In such embodiments, one connection flange of one side plate may overlap with a portion of one attachment flange of an opposite and below side plate.

The connection flanges and the attachment flanges can comprise a securing pattern. The securing pattern can transfer forces between the wall beams and between opposite side plates.

The respective side plates can in some embodiments comprise a connection flange and an attachment flange, which each comprises a respective fixation slot that together receives a fixation member. This is one manner of providing forces transfer from one side of the wall beam to the other side.

The connection flanges and/or the attachment flanges can comprise a plurality of protrusions and a plurality of receiving recesses. The protrusions and the recesses can engage, thus providing force transfer between the side plates.

The said horizontal distance can be a first horizontal distance, and the first and second side plates, respectively, can further comprise a vertical attachment portion, wherein there is a second horizontal distance between the outer faces of the vertical attachment portions of the first and second side plates, respectively. The first horizontal distance can be equal to or larger than the second horizontal distance. The vertical attachment portions can be located between the vertical wall portions.

The wall beam may further comprise an attachment plate that is connected to both opposite side plates.

Preferably, the attachment plate can be made of a fiber-reinforced plastic material. Typically, the material can be the same material as in the side plates.

The attachment plate can typically be attached to the side plates with glue, with bolts, or both.

In embodiments where the side plates comprise connection flanges, the attachment plate can advantageously connect to said connection flanges.

The side plates may comprise a landing element arranged on an inner face of the vertical wall portion.

In some embodiments, among the two side plates of one wall beam, the vertical wall portion of the first side plate constitutes an inner wall face of the aquaculture tank, and the vertical wall portion of the second side plate constitutes an inner wall face of an adjacent aquaculture tank.

In some embodiments, where the aquaculture tank is one of several tanks, the attachment plate can comprise three branches extending from an intersection and into separate side walls of adjacent aquaculture tanks. This enhances the mechanical stability of the adjacent tanks.

Advantageously, the aquaculture tank can further comprise a top wall cover that covers the upper face or edge of the side plates. The top wall cover can comprise three branches that extend from a top wall cover intersection and along separate side walls.

The side plates may further comprise an edge that is arranged between a first part of the side plate extending in a first horizontal direction and a second part of the side plate extending in a second horizontal direction, wherein an angle is present between the first and second directions. The angle is above zero degrees and advantageously not larger than <NUM> degrees. Such side plates are suitable for constructing aquaculture tanks that have a polygonal shape.

Advantageously, one or more side plates can comprise an attachment portion in the form of a recessed step at an end of the side plate. The recessed step can overlap with and connect to an end of an adjacent side plate. In this manner, several side plates can be attached together into longer sections of side plates. In turn, such longer section of side plates can be part of long wall beams.

The aquaculture tank may comprise three or more wall beams that comprises an attachment plate, wherein the attachment plates have different thickness, and wherein the lower-most attachment plate is thicker than the upper-most attachment plate. In this manner, weight and material is saved, as the strength of the upper attachment plates need not be as strong as the lower attachment plates.

In some embodiments, the aquaculture tank can comprise an attachment plate that connects the first side plate to the second side plate, and a landing element that is configured to abut against an adjacent wall beam. The attachment plate and the landing element can advantageously be the same item. In other words, one may use one single component to fulfill the function of the attachment plate and the function of the landing element. These functions will be discussed further below.

The aquaculture tank may further comprise a clamping element configured to clamp the vertical attachment portions of two opposite side plates outwardly against facing vertical wall portions of an adjacent wall beam, wherein the clamping element is configured to be moved from a non-clamping position into a clamping position.

While the present invention has been presented above in general terms, some detailed and non-limiting examples of embodiment will be presented in the following with reference to the drawings, in which.

The present example embodiment relates to a fish tank or a plurality of fish tanks suitable for an onshore aquaculture facility, such as an RAS facility. Thus, the tank or tanks will be suitable for containing water.

<FIG> depicts a plurality of fish tanks <NUM>. The side walls <NUM> of the fish tanks <NUM> can have a substantially polygonal shape, in the present example an octagonal shape. As appears from <FIG>, the fish tanks <NUM> share common side walls. Instead of having an octagonal shape, other shapes are possible. For instance, as will be shown further below, the shape of the side walls may be hexagonal or rectangular.

In other embodiments, the side walls of a tank <NUM> may be circular.

<FIG> depict a portion of a side wall <NUM>. The side wall <NUM> is made up of horizontally extending wall beams <NUM>, of which two are shown in <FIG>. For illustrational purpose, only a short length of the wall beams <NUM> is shown.

Each wall beam <NUM> has a first side plate <NUM> and an oppositely arranged second side plate <NUM>. The first side plate <NUM> has a vertical wall portion 7a and the second side plate <NUM> has a vertical wall portion 9a. Between the vertical wall portions 7a, 9a of the first and second side plates <NUM>, <NUM>, respectively, there is a first distance <NUM>.

Furthermore, the first side plate <NUM> has a vertical attachment portion 7b and the second side plate <NUM> has a vertical attachment portion 9b. Between the outer faces of the vertical attachment portions 7b, 9b of the first and second side plates <NUM>, <NUM>, respectively, there is second distance <NUM>. When an upper vertical wall beam <NUM> is installed onto a lower vertical wall beam <NUM>, the second distance <NUM> is not larger than the first distance <NUM>. Consequently, as shown in <FIG>, the vertical attachment portions 7b, 9b of the lower wall beam <NUM> fits within the vertical wall portions 7a, 9a of the upper wall beam <NUM>.

Preferably, the second distance <NUM> and the first distance <NUM> are equal, such that the vertical attachment portions 7b, 9b fit snugly into the gap between the vertical wall portions 7a, 9a.

The first distance <NUM> can in some embodiments be more than <NUM> or even more than <NUM>.

As appears from <FIG>, the first side plate <NUM> and the second side plate <NUM> are separate parts. they have been manufactured as separate parts and assembled as a part of the side wall <NUM> of the fish tank <NUM>. Above the vertical attachment portions 7b, 9b, the side plates <NUM>, <NUM> curve towards each other, into a connection flange 7c, 9c. In the shown embodiment, the faces of the connection flanges 7c, 9c are horizontal, however in other embodiments they may have another inclination with respect to the vertical attachment portions 7b, 9b.

Fixedly attached to the two connection flanges 7c, 9c there is an attachment plate <NUM>. The attachment plate <NUM> can be fixed to the connection flanges 7c, 9c for instance with glue, bolts or rivets.

As perhaps best illustrated in <FIG>, where one side plate has been removed for illustrational purpose, however also shown in <FIG>, a landing element <NUM> is attached to the inner face of the vertical wall portion 7a, 9a of the side plates <NUM>, <NUM>. In the shown embodiment, the landing element <NUM> is in the form of an angle bracket, wherein one bracket plate is attached to the inner face of the vertical wall portion 7a, 9a.

As appears from <FIG>, the landing element <NUM> is arranged at a distance from the lower edge of the vertical wall portion 7a, 9a. The main technical function of the landing element <NUM> is to ensure a correct mutual position between the upper wall beam and the lower wall beam <NUM>, when the upper wall beam <NUM> lands on the lower wall beam <NUM>.

As shown in <FIG>, the landing element <NUM> will land on the attachment plate <NUM>. The lower parts of the vertical wall portions 7a, 9a can advantageously be fixed to the vertical attachment portions 7b, 9b of the lower (e.g. the previously installed) wall beam <NUM> by means of glue, bolts, or a combination of glue and bolts. Advantageously, the glue may serve both as a means for fixating the wall beams <NUM> together, as well as a means for sealing the wall <NUM>, i.e. making the side wall <NUM> liquid tight.

In the embodiment shown in <FIG>, the connection flanges 7c, 9c are attached to each other by means of the attachment plate <NUM>. In an alternative embodiment, however, one could extend one or both of the connection flanges 7c, 9c such that they overlap each other. In that way, the connection flanges 7c, 9c could be connected directly to each other, such as with glue and/or bolts. In such embodiments, it would be advantageous to displace the mutual vertical positions of the connection flanges 7c, 9c, such that they will overlap each other without displacing the remaining parts of the side plates <NUM>, <NUM>.

In the discussed embodiment, the wall beams <NUM> are downwardly open and landed from above onto the vertical attachment portions 7b, 9b. It shall be clear, however, that the wall beams <NUM> also could be arranged upside down with respect to the shown embodiment. Hence, the use of terms like upper and lower, is merely for explanation.

The side plate <NUM>, <NUM> is advantageously produced in one piece, such as by vacuum moulding. The side plate <NUM>, <NUM> is made of glass-fiber reinforced plastic (GRP) or fiber-reinforced plastic (FRP).

Reference is now made to <FIG>, which is a perspective view of a side plate <NUM>.

At one end of the side plate <NUM>, it comprises a lateral attachment portion 7d. The lateral attachment portion 7d is in the form of a recessed step. The recessed step 7d is configured to be arranged overlapping an adjacent end of another side plate (not shown) such that the recessed step 7d can be attached to the end of the adjacent side plate. The connection can be made by glue and/or bolts. <FIG> depicts the lateral attachment portion 7d of the side plate <NUM> in better detail.

Advantageously, the recced step 7d is displaced with respect to the main faces of the side plate <NUM> with a distance that equals the thickness of the side plate <NUM>.

Thus, when an adjacent side plate is connected to the side plate <NUM>, the main faces of the two side plates will be flush.

The side plate <NUM> shown in <FIG> further comprises an edge 7f. The edge 7f is arranged between a first part 7e of the side plate <NUM> that extends in a first horizontal direction, and a second part <NUM> of the side plate <NUM> that extends in a second horizontal direction. In the shown embodiment, the angle of the edge 7f is orthogonal. The profile of the first part 7e is the same as for the second part <NUM> of the side plate <NUM>. Hence, the first part 7e of the side plate <NUM> will be compatible with a lateral attachment portion 7d of another side plate.

While the angle of the edge 7f between the first and second extensions of the side plate <NUM> shown in <FIG> is orthogonal, the angle may different. The angle of the edge 7f will determine the overall shape of the fish tank <NUM>, i.e. the angle between the adjacent side walls <NUM>.

In some embodiments, the side plates <NUM>, <NUM> may be straight, i.e. without the edge 7f shown in <FIG>.

In some embodiments, the side plates <NUM>, <NUM> may be curved, thus being suitable for a curved side wall <NUM>. Such curved side walls <NUM> may together form a circular shaped tank <NUM>. A combination of straight and curved side walls <NUM> is also possible.

As the skilled person will understand from <FIG>, a plurality of side walls <NUM>, such as shown in <FIG>, can be readily stacked for storage and transport. One face of one side wall <NUM> will substantially be equal to the opposite face (i.e. a facing face) of another side wall <NUM>.

<FIG> depicts a cross section view through two side plates <NUM> that are joined. The lateral attachment portion 7d overlaps with the end of the adjacent side plate. Furthermore, a strip <NUM> of an elastic and curing material is arranged to seal the interface between the two side plates and to avoid sharp edges.

<FIG> is a view corresponding to <FIG>. However, <FIG> depicts the interface between the vertical wall portion 7a one side plate <NUM> and the vertical attachment portion 7b of an adjacent side plate <NUM>.

<FIG> is a cross section view through a complete height of a side wall <NUM>. In this embodiment, the side wall <NUM> comprises seven wall beams <NUM> that are stacked on top of each other. The added height of each wall beam <NUM> can for instance be between <NUM> and <NUM>. With the term added height is meant the increase of height that is obtained by installing one wall beam <NUM> onto a previous wall beam <NUM>. Thus, with the embodiment shown in <FIG>, the total height of the side wall <NUM> can typically be between <NUM>,<NUM> and <NUM>,<NUM>.

<FIG> depict two alternative embodiments of a foot wall beam <NUM>. The design of the foot wall beams <NUM> may resemble the previously discussed wall beams <NUM> in many respects. For instance, they can be provided with side plates <NUM>, <NUM> that comprise a vertical wall portion 107a and a vertical attachment portion 107b. However, at their lower sections, they are provided with a foot flange <NUM>, <NUM>.

In some embodiments, the foot flanges <NUM>, <NUM> extend with a substantially horizontal orientation, out from the side wall <NUM>, i.e. out from the main portion of the wall beam <NUM>. In other embodiments, as depicted in <FIG>, a first foot flange <NUM> extends out from the side wall <NUM>, while the second foot flange <NUM> extends in the same direction as the first foot flange <NUM>. In this manner, one is able, for instance, to assemble the fish tank <NUM> immediately next to a vertical wall, such as the inner face of a building wall, or any other object. The fish tank <NUM> will in this manner reduce its footprint.

<FIG> is a cross section view through the upper wall beam <NUM>. Instead of another wall beam <NUM> landed on top of it, there is arranged a top wall cover <NUM>. The top wall cover <NUM> fulfills, inter alia, the technical purpose of the attachment plate <NUM> used in the lower wall beams <NUM>. The top wall cover <NUM> comprises a horizontal portion 17a. On both sides of the horizontal portion 17a extend a vertical, downwardly extending side flange 17b. The distance between the two side flanges 17b corresponds to the second distance <NUM>, i.e. the distance between the outer faces of the vertical attachment portions 7b of the side plates <NUM>, <NUM>.

The top wall cover <NUM> can advantageously be fixed to the side plates <NUM>, <NUM> by means of glue and/or bolts. Possible bolts may advantageously penetrate through the side flanges 17b, thereby leaving the horizontal portion 17a intact.

<FIG> depicts a portion of a tank system having a plurality of fish tanks <NUM>, such as depicted in <FIG>. In the shown view, three side walls <NUM> meet at an intersection <NUM>. At the position of the intersection <NUM>, the attachment plate <NUM> comprises three branches 11a.

Thus, the three interfacing side walls <NUM> comprise a plurality of attachment plates <NUM> that connect the side walls <NUM> rigidly together with their attachment plate branches 11a. On top of the upper-most wall beam <NUM>, there may be a (not shown) top wall cover <NUM> having three top wall cover branches, similar to the attachment plate branches 11a. Thus, a strong mechanical integrity of the fish tanks <NUM> is provided.

<FIG> is a schematic cross section view of three side plates <NUM>, depicting how several side plates <NUM> are suitable for being stacked in a compact fashion for storage or transport.

<FIG> depict two further overall shapes of the fish tanks <NUM>. <FIG> depict fish tanks <NUM> having a hexagonal layout, while <FIG> depict fish tanks <NUM> that have a square layout.

<FIG> shows how a stack of curved side plates <NUM> are joined into a stack of wall beams <NUM> that together form a tank wall <NUM>. In this image, some side plates are removed for illustrational purpose.

<FIG> depicts a series of connected side plates <NUM>, typically connected by gluing and / or bolting their lateral attachment portions 7d, e.g. the recessed steps, to the end portion of the adjacent side plate <NUM>. As the skilled reader will appreciate, the connected side plates <NUM> shown in <FIG> would fit with the embodiment shown in <FIG>.

<FIG> is a perspective view of a side wall <NUM> of a tank, with the wall cut off for illustrational purpose.

<FIG> is a schematic cross section view through the interface between two wall beams <NUM>, each having a first and a second side plate <NUM>, <NUM>. In the embodiment shown in <FIG>, the attachment plate <NUM> that connect the side plates <NUM>, <NUM> is the same item as the landing element <NUM>. As shown, the attachment plate <NUM> and the landing element <NUM>, which are the same item, has a substantially flat, horizontal surface with two side flanges arranged orthogonally with respect to the flat, horizontal surface.

Still referring to <FIG>, layers of glue <NUM> are indicated between the vertical wall portions 7a, 9a and the vertical attachment portions 7b, 9b of the side plates <NUM>, <NUM>. A clamping element, here shown as a clamping plate <NUM>, is configured to be moved into a clamping position between the vertical attachment portions 7b, 9b. When in the clamping position, it compresses the glue between the vertical attachment portions 7b, 9b and the vertical wall portions 7a, 9a, thus ensuring a solid connection between the adjacent wall beams <NUM>.

In the shown embodiment, a layer of glue <NUM> is also arranged between the clamping plate <NUM> and the attachment plate <NUM>.

To enable movement of the clamping plate <NUM> between the non-clamping position and the clamping position, the attachment plate <NUM> is provided with access apertures <NUM>. Hence, one will be able to force the clamping plate <NUM> into the clamping position for instance by forcing it into position with a rod extended through the access aperture <NUM>.

In the situation shown in <FIG>, an upper wall beam <NUM> is about to be installed on a lower wall beam <NUM>. Advantageously, both the side plates <NUM>, <NUM> and the attachment plate <NUM> are made of a fiber-reinforced plastic material. Hence, the material is somewhat flexible. To insert the vertical attachment portions 7b, 9b into the first distance <NUM>, i.e. between the vertical wall portions 7a, 9a, the vertical wall portions 7b, 9b are flexed towards each other. In this manner, one avoids scraping off or moving the layers of glue <NUM>. To obtain the flexed configuration shown in <FIG>, one may simply use manual force while moving the wall beams together. In addition, or instead, one could also temporarily introduce an installation element (not shown) between the vertical wall portions, above the attachment plate <NUM>, so as to obtain the non-parallel configuration of the side plates <NUM>, <NUM>.

<FIG> illustrates an alternative embodiment of the present invention. In this embodiment, the vertical attachment portions 7b, 9b are larger than the vertical wall portions 7a, 9a.

<FIG> shows the lower portion of one wall beam <NUM> landed on the upper part of another wall beam <NUM>, according to another embodiment. According to this embodiment, the two opposite side plates <NUM>, <NUM> are not attached by introducing the vertical attachment portions 7b, 9b into the gap between the vertical wall portions 7a, 9a. Instead, the side plates <NUM>, <NUM> further comprise attachment flanges 7i, 9i in addition the connection flanges 7c, 9c. The attachment flanges 7i, 9i extend parallel to the connection flanges 7c, 9c, at the opposite vertical ends of the side plates <NUM>, <NUM>. Hence, the upper wall beam <NUM> is landed on the lower wall beam <NUM> by landing the attachment flanges 7i, 9i onto the connection flanges 7c, 9c, as illustrated in <FIG>. A plurality of bolts <NUM> are used to attach the flanges together. In this embodiment, there is also arranged a fixation plate <NUM> that adsorbs the tensioning forces of the bolts <NUM>.

<FIG> depicts a principle view of one side plate <NUM> that is provided with both the connection flange 7c and the attachment flange 7i. Both the connection flange 7c and the attachment flange 7i are provided with bolt apertures <NUM>. The bolt apertures <NUM> are configured to receive bolts <NUM>, for connection to the neighboring side plate <NUM>. Furthermore, to provide access to the bolts <NUM> during installation, the attachment flange 7i is provided with access apertures <NUM>. Thus, when the side plate <NUM> has landed on top of a previous side plate (not shown in <FIG>), with bolts <NUM> protruding up through the bolt apertures <NUM> of the connection flange 7c, a tool (not shown) can be inserted through the access aperture <NUM> to secure a nut (not shown) onto the bolt <NUM>.

In some embodiments, the bolts <NUM> can be pre-attached to the attachment flange 7i, protruding upwards.

In the embodiment shown in <FIG>, the access apertures <NUM> of the attachment flange 7i are located directly above the bolt apertures <NUM> of the connection flange 7c. In this manner, the tool (not shown) can be directed directly onto the awaiting bolt <NUM> without an angle. In such embodiments, however, the position of the access apertures <NUM> of the succeeding side plate <NUM> should be displaced, such that the bolt apertures <NUM> of the connection flange 7c and the attachment flange 7i are aligned.

<FIG> depicts an embodiment where the connection flange 7c and the attachment flange 7i comprise a plurality of protrusions <NUM> and a plurality of receiving recesses <NUM>. In <FIG> the side plates <NUM>, <NUM> are shown in an exploded view for illustrational purpose. When assembled, the protrusions <NUM> will extend into the receiving recesses <NUM>. In addition, bolts <NUM> (not shown) will extend through the bolt apertures <NUM>.

The engagement between the protrusions <NUM> and the receiving recesses <NUM> will transfer shear forces between the opposite side plates <NUM>, <NUM>. Such shear forces can typically be significant if for instance one tank <NUM> is filled with water, while an adjacent tank <NUM> is empty. The hydrostatic pressure will then flex the wall <NUM> into a curved shape, and thus expose the wall <NUM> to shear forces.

While the protrusions <NUM> and receiving recesses <NUM> of the shown embodiment comprise edges extending in a longitudinal and crosswise direction, with respect to the longitudinal direction of the wall beams <NUM>, other embodiments may have a different pattern. For instance, the protrusions <NUM> and the receiving recess <NUM> may have a zig-zag pattern, or for instance a sinusoidal pattern.

Moreover, still referring to <FIG>, in the shown embodiment, the protrusions <NUM> of the connection flange 7c of the first side plate <NUM> overlap the protrusions <NUM> of the attachment flange 9i of the second side plate <NUM>. In this manner, additional fixation of the opposite side plates <NUM>, <NUM> can be obtained, for instance by providing glue or an adhesive between the overlapping protrusions <NUM>.

<FIG> depicts another embodiment, wherein the connection flanges 7c, 9c and the attachment flanges 7i, 9i of the respective side plates <NUM>, <NUM> extend horizontally and crosswise to the longitudinal extension of the wall beams <NUM>, with different lengths. This is better shown with the cross section view of <FIG>, wherein a second side plate <NUM> is shown with the connection flange 9c having a longer crosswise, horizontal extension than its attachment flange 9i. With such a system, as shown in <FIG>, the first side plate <NUM> will have the opposite difference, namely a connection flange 7c with a smaller extension than the attachment flange 7i.

A result of the different horizontal extension is that the connection flange 7c, 9c of one side plate <NUM>, <NUM> will overlap with the attachment flange 7i, 9i of the opposite, overlying or underlying side plate <NUM>, <NUM>. This enables the opposite side plates <NUM>, <NUM> to be connected to each other, for instance by applying glue between the flanges at the overlapping portion.

The embodiment discussed with reference to <FIG> above is shown with a cross section view in <FIG>. In addition, as shown in <FIG> and in <FIG>, there is arranged a fixation slot 7j, 9j in the attachment flange 7i of the first side plate <NUM> and in the connection flange 9c of the second side plate <NUM>. The two fixation slots 7j, 9j extend in the longitudinal direction of the side plates <NUM>, <NUM>. Furthermore, two fixation slots 7j, 9j oppose each other and are aligned with each other, such that they together can receive an elongated fixation member <NUM>. The fixation member <NUM> fits snugly into the two aligned fixation slots 7j, 9j, and thus contributes to maintaining the opposite side plates <NUM>, <NUM> together. The fixation member <NUM> can be inserted into the fixation slots 7j, 9j with a longitudinal movement, or it can be landed into the upwardly facing fixation slot 9j before the opposite side plate <NUM> is landed.

<FIG> depicts the upper portion of a first side plate <NUM>. The upper face of the connection flange 7c is provided with a securing pattern <NUM>. The securing pattern <NUM> of the embodiment shown in <FIG> comprises pattern edges 41a that extend with an inclined direction, with respect to the longitudinal direction of the first side plate <NUM> (and thus with respect to longitudinal direction of the wall beam <NUM>). This securing pattern <NUM> is configured to engage with an opposite (not shown) securing pattern on the downwardly facing face on the attachment flange 7i of the first side plate <NUM> (not shown) above it. It will thus be understood that among the two engaging securing patterns <NUM>, the recesses of one pattern will receive protrusions of the opposite pattern.

The securing pattern <NUM> shown in <FIG> is thus configured to transfer forces between the two vertically stacked first side plates <NUM> both in the longitudinal and crosswise directions.

It will be understood that also the second side plate <NUM> will be provided with the securing pattern <NUM> on the connection flange 9c and on the facing attachment flange 9i.

<FIG> depicts a similar embodiment. However, in the embodiment shown in <FIG>, the pattern edges 41a of the securing pattern <NUM> extend in a direction perpendicular to the longitudinal extension of the first side plate <NUM>.

Finally, <FIG> shows an embodiment wherein the pattern edges 41a of the securing pattern <NUM> is in the form of circles. This securing pattern <NUM> comprises a plurality of upwardly extending protrusions. As will be understood, the oppositely facing securing pattern <NUM> of the attachment flange 7i will thus comprise receiving recesses (not shown) that receive the protrusions.

In some embodiments, the side plates <NUM>, <NUM> can comprise connection flanges 7c, 9c and attachment flanges 7i, 9i of different length, such as shown in <FIG> and in <FIG>, wherein the overlapping portions comprise a securing pattern <NUM>.

The fish tanks <NUM> discussed herein can be stored and transported in a relatively compact state, since the main parts are configured to be stacked in a compact state. This advantage facilitates transport of large fish tanks <NUM> even remote from the sea, i.e. without the use of seagoing vessels.

The light weight of the composite plastic material, such as GRP, which is used to manufacture the side plates <NUM>, <NUM>, results in fish tanks <NUM> having relatively light weight. Another advantage of using composite plastic material, is its ability to adapt to ground settling better than a corresponding fish tank made of concrete.

Yet a further advantage of the presented tank <NUM>, is that it is possible to disassemble it in a non-destructive manner and possible re-assemble it. This contrasts to known tanks made in concrete, which will require a significant effort for disassembly.

The side plates <NUM>, <NUM> can typically have a thickness in the range between <NUM> to <NUM>.

The tank <NUM> according to the present invention can typically accommodate <NUM> to <NUM><NUM> of water.

Arranging the wall beams <NUM> in a horizontal orientation is advantageous since they are then suited for adsorbing tensile forces resulting from the pressure from the contained water.

Claim 1:
A fiber-reinforced plastic material aquaculture tank (<NUM>) comprising side walls (<NUM>), wherein the side walls (<NUM>) comprise a plurality of horizontally oriented wall beams (<NUM>) stacked vertically on top of each other, wherein the respective wall beams (<NUM>) comprise a first side plate (<NUM>) and an oppositely arranged second side plate (<NUM>), wherein the first and second side plates (<NUM>, <NUM>), respectively, comprise
- a vertical wall portion (7a, 9a), wherein there is a horizontal distance (<NUM>) between the vertical wall portions (7a, 9a) of the first and second side plates (<NUM>, <NUM>), respectively;
and wherein the first and second plates (<NUM>, <NUM>) are made of a fiber-reinforced plastic material,
wherein the side plates (<NUM>, <NUM>) further comprise connection flanges (7c, 9c) that extend parallel to the horizontal extension of the wall beams (<NUM>), and wherein the connection flanges (7c, 9c) of the respective two oppositely arranged side plates (<NUM>, <NUM>) curve towards each other,
characterized in that the connection flanges (7c, 9c) comprise bolt apertures (<NUM>) and access apertures (<NUM>).