WO2010134825A1

WO2010134825A1 - Net cage construction

Info

Publication number: WO2010134825A1
Application number: PCT/NO2010/000186
Authority: WO
Inventors: Ulrik Ulriksen
Original assignee: Ocea As
Priority date: 2009-05-20
Filing date: 2010-05-20
Publication date: 2010-11-25
Also published as: NO330203B2; NO330203B1; GB2484607A; NO20091963L; GB2484607B; GB201120562D0

Abstract

A net cage construction (50) is described comprising a number of floating tubes (12) and also a number of clamps (10) arranged mutually spaced apart around the floating tubes (12), where said clamps (10) comprise at least two ring-formed casings (22) with a respective through-running opening (14) that surrounds the floating tube (12), and which is connected via intermediate cross struts (24, 26, 28) to take up and retain the respective floating tubes (12), and that in said cross struts is arranged a connection (16) for rods (18) or chains that run to other clamps (10) on the net cage (50). Said connection (16) is formed as a common quick connection for the uptake of said rods (18) or chains and for the uptake of mooring chains (20), as the rods (18) or the chains arranged between mutual clamps (10) are arranged to take up the primary forces that run around the net cage construction (50) to relieve the forces in the floating tubes (12), and that said primary forces are transferred via the common connection (16) to the mooring chains (20). A method of assembling a net cage construction is also described.

Description

Net cage construction

The present invention relates to a net cage construction comprising a number of floating tubes and also a number of clamps arranged mutually spaced apart around the floating tubes, where said clamps comprise at least two ring-formed casings with a respective through-running opening that surrounds the floating tube, and which is connected via intermediate cross struts to take up and retain the respective floating tubes, and that a connection for rods or chains is arranged in said cross strut, that runs to other clamps on the net cage. The invention also relates to a method for assembling a net cage construction.

Traditionally, plastic net cages have been constructed in that the floating tubes, normally made from a PE material (polyethylene) , have a primary safety function for the construction. The floating tube takes up all the forces and distributes these further out to the mooring system. This means that the floating tubes must have relatively thick walls to be able to take up these forces.

On these traditional net cages it has also been normal with chain or rod connections between the clamps so that the clamps shall retain their position on the construction. The chain or rod connections have also been dimensioned as "secondary safety" with the purpose of avoiding that the construction ruptures at a possible breakdown (for example, at a break in the floating tubes) .

The present net cage concept is separate from this, in that the primary and secondary safety functions are reversed. This is achieved through a unique construction where the primary forces operate through integrated rod/chain connections instead of the floating tubes. The chain/rod connections, preferably around the whole net cage, have a primary safety function in that these take up the forces that act on the construction, and transfer these to the mooring system. The floating tubes can still take up some forces, but these are, in the main, tied to the requirement that the construction shall retain its preferably round shape, and also that they shall be buoyancy-providing components in the construction. The floating tubes also have a secondary safety function with the purpose of avoiding that the construction "ruptures" at a possible breakdown, for example, a break in the chain/rod connection.

The forces that are taken up by the chain/rod connections are transferred to the mooring system via integrated fastening elements in the clamps. Thus, the construction of multi-functional, integrated fastening elements is unique. By combining floating tubes and clamps, the rods are quick connected in that hawse pipes, for example, are fastened in the clamp. The novel value of this construction is also that the mooring is mounted through the quick connection. This solution provides an extra safety in that the mooring is secondary-safety to the hawse pipe and therefore secondary safety to the rod connections also (which shall take up most of the forces in the construction) .

From prior art, reference is made, among others, to brochures from the firm Aqualine; "New generation net cages", www. aqualine. no/aqualine/EntryPage . asps, and "The AQUALINE Cage" brochure from 2001.

Aqualine shows solutions with clamps which, in many ways, can seem like the clamps described in the present application. Furthermore, it can also be seen that rods run between the clamps and are fastened to cross struts on the clamps. However, it can clearly be seen that the secondary forces are taken up by the rods between the clamps. In both solutions, the forces are transferred directly from steel clamps to floating ring/plastic tubes. Aqualine describes this as "our well tested secondary safety". Furthermore, a safety chain is shown which clearly has the purpose of ensuring that the tubes or the clamps do not slide away from each other if a rupture should occur. This must be considered to be a verification that the primary forces go through the plastic tubes.

With the present invention one aims to achieve the opposite of what is described in the brochures from Aqualine, namely that the primary forces are taken up by the rods and not the plastic tubes, and that these primary forces are transferred directly to the net cage mooring chains. The task for the plastic tubes is thereby no longer to hold the net cage together, but mainly to hold the net cage construction afloat.

According to the present invention the mooring lines have a direct connection to the rods that distribute the forces around the ring. It is the combination of this that constitutes the primary forces. To achieve this, a common connection is connected in the cross strut of the clamps, in which both the rod and mooring chains are fastened together at the same point. Thus, the rods form a connection around the whole of the net cage, dimensioned for the uptake of the primary forces in the construction. A person skilled in the art that faces the problem of reducing the forces that act on the plastic tubes, to thereby achieve a cost reduction, will not be led towards the present invention based on the information from Aqualine, as it is stated in said documents that the primary forces are taken up by the tubes and that the rods take up secondary forces. From a starting point based on Aqualine, a person skilled in the art will therefore be led away from the present invention.

Furthermore, according to Aqualine, the clamps are mounted with "Mooring lugs", which must be assumed to be a fastening for the mooring chains, but there is no mention of a common connection for chains and rods, and which is in the form of a connecting tube or the like that runs through the cross struts to the clamp.

With the present invention all dimensioning forces will go through the steel construction, i.e. the clamps and the rods, and not via the plastic tubes. This leads to reduced requirements being set for the strength of the plastic tubes (thinner walls).

To emphasis this one can, for example, initially base it on a pipe dimension of ø500 mm. Calculations have shown that with the present solution, SDR 17 PEHD quality can be used, while where the primary forces are taken up by the plastic tubes SDR 13.6 must be used. Technical specifications for plastic tubes show that a metre length with SDR 17 weighs 45.1 kg, while SDR 13.6 weighs 52.4 kg. The weight difference is 7.3 kg/m.

A 160 m floating plastic collar comprising two floating tubes has a total of about 320 metres of the ø500 mm tube. The reduction in weight with a typical price for the plastic (NOK 17 per kg) results in the following cost saving for the raw material: 320 m x 7.3 kg/m x NOK 17/kg = NOK 39 700, i.e. nearly NOK 40 000 per net cage construction .

Even if the distribution of loads (primary/secondary) demands somewhat stronger steel, this does not constitute more that about 1/4 of the cost saving, and the present solution will thereby provide savings with regard to the known solutions.

Consequently, it is an object to provide a clamp solution that uses chain or rod connections as a primary safety function on net cages to relieve the load on the floating tubes. It is a further object to provide a solution that can be used on clamps made from different materials, and which can be used on floating tubes of different materials.

It is also an object to reduce the forces that act on the plastic tubes to achieve a cost saving as less tubing can be used.

The above mentioned objects are achieved with a clamp as described in the independent claim 1 in that the connection in the clamp is formed as a common quick connection for uptake of rods or chains and for uptake of mooring chains, as the rods or chains placed between mutual clamps are arranged to take up primary forces that run around the net cage construction to relieve the forces on the floating tubes, and that said primary forces are transferred via the common connection to the mooring chains.

Alternative embodiments of the net cage construction are given in the dependent claims 2-5.

The mooring chains can be arranged to function as secondary safety for the connection to each clamp and as secondary safety for said rods or chains.

The connection can be in the form of a tube that runs at least partially through the cross struts in the clamp. The lower cross strut can comprise a fastening or holding part to receive a lower part of the connection, and the upper cross strut can comprise fastening means for fastening of the connection.

A second tube can run at least partially through one or more of the cross struts arranged for the fastening of a further chain or the like.

Said objects are also achieved with a method given in the independent claim 6 for mooring and assembly of floating tubes to a net cage construction; in which a number of floating tubes are connected with a number of clamps that are arranged mutually spaced apart about the floating tubes, as the clamp comprises at least two ring-formed casings with a respective through-running opening that surrounds the floating tube and which is connected via intermediate cross struts for the uptake and retention of respective floating tubes, and that rods or chains that run to other clamps on the net cage are fastened to a connection in said cross strut comprising the following steps:

- that the mooring chains are fastened to the connection, and

- that the rods or chains between mutual clamps are fastened to the same connection, so that primary forces in the net cage construction to relieve the forces in the floating tubes run through the rods and are transferred via the common connection to the mooring chains.

An alternative embodiment of the method is given in the dependent claim 7 in that in the assembly of floating tubes and clamps the rods are quickly connected in that said connection is beaten in place in the clamp and that the mooring chain is mounted to the connection at the same time. The invention shall now be described in more detail with reference to the enclosed figures, in which:

Figure 1 shows a net cage construction according to the invention.

Figure 2 shows in more detail a section of floating pipes and clamps according to the invention. Figure 3 shows an outline of a clamp according to the invention seen from the side.

Figure 1 shows a net cage construction 50 that comprises a number of floating tubes 12 that are held in place with the help of a number of clamps 10 arranged around the net cage. A net bag 52 is placed in the net cage, where the net bag will, in a known way, contain the maritime species that shall be farmed in the net cage. Furthermore, the net cage construction 50 is held in place by a mooring system comprising a number of mooring chains 20. These mooring chains 20 can run out at an angle and into the water from several different clamps and they can also run down along the net bag 52 to, for example, lower fastening rings for fastening of the net bag in the net cage.

Figure 2 shows in more detail a section of an embodiment example in which two floating tubes are placed next to each other, and where the floating tubes are held together with the help of more clamps 10 arranged mutually spaced apart around the net cage construction. A rod 18 or chain runs between the clamps 10. A rod is shown to the right in figure 2, while the left side of figure 2 shows a chain. This can, of course, be the other way around, or both rod and chain can be used between the clamps.

A clamp 10 according to the invention is shown in more detail in figure 3. As can be seen, the clamp comprises at least two ring-formed casings 22 which can be threaded onto the floating tubes 12 or be fastened in another way to combine the floating tubes. The casings 22 can be whole or alternatively possibly open. A number of cross struts run between the ring-formed casings. In the example shown, an upper cross strut 24, an intermediate cross strut 26 and a lower cross strut 28 run between the ring-formed casings .

From one of the casings 22 and/or the upper cross strut 24, a support railing 36 stretches upwards, where the support railing 36 can also be equipped with a suspension point 38 for the net bag 52 or other equipment that can be hung onto the clamp 10.

As mentioned earlier, chain or rod connections between the clamps have been used in traditional net cages, so that the clamps shall retain their position on the construction. Chain or rod connections have also been dimensioned as "secondary safety" with the purpose ofavoiding tearing at a possible breakdown. So that the rod 18 or the chain shall be able to take up primary forces, a quick connection is arranged in the form of a hawse pipe 16 in the clamp 10. This hawse pipe 16 can stretch all the way or partially through said cross struts 24, 26, 28, and is arranged for quick coupling with one or more mooring chains 20, so that the forces from the rods 18 or the chains are transferred through the hawse pipe 16 to the mooring chains 20. In this way, it is avoided that the floating tubes 12 take up much of the forces. Even if the floating tubes should take up some forces, this will be minimal in comparison to the known solutions. Furthermore, the mooring chains. 20 will function as secondary safety for the connection 16 in each clamp 10, and as secondary ^■safety for said rods 18 or chains. The hawse pipe 16 can be placed in the clamp 10 and, in addition as an extra safety, the lower cross strut 28 (alternatively the intermediate cross strut), can comprise a fastening or holding part 30 to receive a lower part of the hawse pipe 16 and the upper cross strut 24 can comprise fastening means 32 for fastening of the hawse pipe 16, for example, a screw or a bolt connection.

The clamp 10 can further be equipped with a second hawse pipe 34, which can also run through one or more of said cross struts 24, 26, 28. This second hawse pipe 34 can function as a suspension point for chains or the like that run down along the net cage, for example, to hold or secure the net bag, or also to moor the net cage. Alternatively, said rod 18 or chains can be fastened to the second hawse pipe 34, or a double set of rods 18 or chains can run between the clamps, fastened to the respective hawse pipes 16, 34.

Claims

C L A I M S

1. Net cage construction (50) comprising a number of floating tubes (12) and also a number of clamps (10) arranged mutually spaced apart around the floating tubes (12), where said clamps (10) comprise at least two ring- formed casings (22) with a respective through-running opening (14) that surrounds the floating tube (12), and which is connected via intermediate cross struts (24, 26, 28) to take up and retain the respective floating tubes (12), and that in said cross strut it is arranged a connection (16) for rods (18) or chains that run to other clamps (10) on the net cage (50), c h a r a c t e r i s d i n that said connection (16) is formed as a common quick connection for the uptake of said rods (18) or chains and for the uptake of mooring chains (20), as the rods (18) or the chains arranged between mutual clamps (10) are arranged to take up the primary forces that run around the net cage construction (50) to relieve the forces in the floating tubes (12), and that said primary forces are transferred via the common connection (16) to the mooring chains (20).

2. Net cage construction (50) according to claim 1, c h a r a c t e r i s e d i n that the mooring chains

(20) are arranged to function as secondary safety for the connection (16) in each clamp (10) and as secondary safety for said rods (18) or chains.

3. Net cage construction (50) according to claim 1, c h a r a c t e r i s e d i n that said connection (16) is formed as a tube that runs at least partially through the cross struts (24, 26, 28) in the clamp (10) .

4. Net cage construction (50) according to claim 3, c h a r a c t e r i s e d i n that the lower cross strut (28) comprises a, fastening or holding part (30) to receive a lower part of the connection (16) and that the upper cross strut (24) comprises fastening means (32) for permanent fastening of the connection (16).

5. Net cage construction (50) according to claim 3, c h a r a c t e r i s e d i n that a second tube (34) runs at least partially through one or more of the cross struts (24, 26, 28) arranged for fastening of a further chain or the like.

6. Method for mooring and assembly of floating tubes (12) of a net cage construction (50), in which a number of floating tubes (12) are connected to a number of clamps (10) that are arranged mutually spaced apart around the floating tubes (12), as the clamps (10) comprise at least two ring-formed casings (22) with a respective through- running opening (14) that surrounds the floating tube

(12), and which is connected via intermediate cross struts (24, 26, 28) to take up and retain respective floating tubes (12), and that rod (18) or chains that run to other clamps (10) on the net cage (50) are fastened to a connection (16) in said cross strut, c h a r a c t e r i s e d in the following steps:

- that mooring chains (20) are fastened to the connection (16), and

- that the rods (18) or chains between mutual clamps (10) are fastened to the same connection (16) so that the primary forces in the net cage construction (50), to relieve the forces in the floating tubes (12), run through the rods (18) and are transferred via the common connection (16) to the mooring chains (20).

7. Method according to claim 6, c h a r a c t e r i s e d i n that during assembly of the floating tubes (12) and clamps (10) the rods (18) are quick connected in that said connection (16) is beaten in place in the clamp (10) and that the mooring chain (20) is mounted to the connection (16) at the same time.