DESC:FIELD OF THE INVENTION

[001] The present invention relates to systems and methods for protecting marine surfaces against biological fouling, and more particularly to a marine anti-fouling device for preventing marine growth on offshore platform structures semi-submerged in water.

BACKGROUND OF THE INVENTION

[002] Fouling is the accumulation of unwanted material on solid surfaces subjected to harsh environment to detriment its function. The fouling materials can consist of either living organisms or a non-living substance (inorganic or organic). Fouling occurs on a surface of a component performing a defined and useful function and impedes or interferes with its ability to perform the function efficiently. Water submerged structures such as ship hulls, pipelines, offshore oil platforms etc are always subjected to harmful effects of harsh climatic conditions and fouling is one of the major concerns.

[003] Marine growth (also referred to as fouling or bio-fouling hereafter) increases the roughness of the exposed surfaces, and grows in the form of a sheath or coating, which add substantial mass to submerged members and increase the effective dimensions or volume of the members. It also obscures visibility of surface, thus preventing necessary visual inspection of the structure.

[004] Offshore platforms used in the oil and gas industry are formed of large diameter pipe elements in the form of vertical, horizontal or inclined legs interconnected by other tubular members. The legs are semi-submerged in sea water and the splash zone where the air meets water is the area of the legs which is prone to fouling.

[005] In order to allow the component to deliver its intended function for the duration of its life, it is necessary to remove or prevent the formation of such fouling on the surface of the structure. Anti-fouling is the process of removing or preventing these accumulations from forming.

[006] The most common anti-fouling method for removing the marine growth is by scrapping the surface with blades. Sea divers need to take a deep dive along with cleaning instruments and scrap the structure to clean the submerged structures. This method is very tedious and involves high cost and skills. Another method is to apply coatings on the structure which does not allow any fouling to stick on the surface; however the coating also wear out with time and the application of coating on huge surface is also prohibitively expensive.

[007] Another drawback with coatings is that, the submerged surfaces have to be brought outside water to apply coating and let it cure before putting the structure again in application. This may not be possible for most of the structures.

[008] Other technique uses Ultrasonic waves and continuous current supply to inhibit microorganism settlement on the submerged structure surface. However the requirement of power source and sophisticated sensors and instruments limit use of this technique.

[009] Accumulation of marine fouling on an offshore structure influences the overall and local loading on in several ways. Layer wise coating of biological species increasing the diameter of structure causing increase in overall projected area and hence hydrodynamic loading. Fatigue life of structure is greatly affected by the marine growth compare to wave loading and hence need extra care in fatigue loading calculations while designing offshore structures. Decrease in inertial coefficient and increase in drag coefficient observed for hard layers of marine growth on offshore constructions whereas relation between marine growth and drag is not clearly understood for the soft/flexible growth. Change in frequency due to added mass alters the dynamic behavior of the structure and hence changes the vortex shedding pattern. This vortex shedding frequency is not considered as problem unless it reaches to the domain in which vortex shedding frequency is close to the natural frequency of the structure causes resonance condition which can lead to catastrophic failure.

[0010] Several factors are responsible for the random nature of fouling which ultimately creates problem for engineers with design and in-situ maintenance of offshore structures. In the early days, anti-fouling coatings were used to prevent ship hulls from the formation of layer of the bio species which affects the performance of the ship. This early paint (coatings) faced harsh criticism from the environmentalist due to their leaching into ocean and side effects on marine life. Several researches are going in this area to form non-toxic coating. Apart from chemical solution there are different techniques are developed to root out this fouling issue such as mechanical devices, ultrasonic techniques, UV radiation, bleaching injection, electrochemical solutions and so on. By considering all these factors and demand for cheap solution this paper presents the mechanical solution against fouling which is not affecting the environment and the system (offshore structures, rigs etc.) along with durable in aggressive ocean conditions and consumes no power as it is powered by ocean wave and current.

[0009] In view of the limitations inherent in the available anti fouling methods for removing marine growth, there exists a need for an anti-fouling device which overcomes the disadvantages of the prior art and which can be used in a simple, cost effective, reliable, secure and environmental friendly manner.

[0011] The present invention fulfils this need and provides further advantages as described in the following summary.
SUMMARY OF THE INVENTION

[0012] In view of the foregoing disadvantages inherent in the prior arts, the general purpose of the present invention is to provide an improved combination of convenience and utility, to include the advantages of the prior art, and to overcome the drawbacks inherent therein.

[0013] A primary objective of the present invention is to provide a device and method for indicating failure of a surge arrester in an electrical system which is simple and cost effective.

[0014] In one aspect, the present invention provides a marine anti-fouling device for removing a marine growth from a structure. The device comprises a plurality of wings, each wing including a flap and at least two wing eyelets, a plurality of horizontal and vertical rollers which are adapted to clean the structure by rubbing, a plurality of clearance links and lock links, each of the clearance and the lock link is adapted to allow mounting of the horizontal rollers and connecting two adjacent wings and a plurality of pins to allow mounting of the vertical roller and connect the clearance link and the lock link with the wing.

[0015] In another aspect of the present invention, the device moves up and down along the structure by an ocean current force.

[0016] In yet another aspect of the present invention, a chain link is formed by connecting a first wing with a second wing by two lock links and the second wing and a third wing by two clearance links.

[0017] In another aspect of the present invention, the chain link is connected to other similar chain links in a closed chain to form the device.

[0018] In one aspect of the present invention, the flap has an aerofoil cross section and the two wing eyelets are located on an edge of the flap on a top and a bottom portion with common axis.

[0019] In another aspect of the present invention, the vertical roller is mounted between the two wing eyelets using the pin.

[0020] In one aspect of the present invention, each of the clearance link and the lock link includes a middle cylindrical portion with two link eyelets at its ends, such that the middle cylindrical portion holds the horizontal roller.

[0021] In another aspect of the present invention, the horizontal roller can rotate about its axis and slide along the middle cylindrical portion.

[0022] In yet another aspect of the present invention, the clearance link eyelets are disposed on two sides of the vertical roller towards inside of the two wing eyelets and the lock link eyelets are disposed on outside of the two wing eyelets with the pin inserted inside to secure the connection.

[0023] In a further aspect of the present invention, the device is adapted to be connected with other similar device using a plurality of flexible connectors with a plurality of floaters.

[0024] In another aspect of the present invention, the floaters keep the devices separated and adds to a buoyant force on the device.

[0025] These together with other aspects of the invention, along with the various features of novelty that characterize the invention, are pointed out with particularity in the description annexed hereto and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and the specific objects attained by its uses, reference should be made to the accompanying drawings and descriptive matter in which there are illustrated exemplary embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The advantages and features of the present invention will become better understood with reference to the following more detailed description taken in conjunction with the accompanying drawings in which:

[0027] FIG. 1 illustrates a marine anti-fouling device, according to one embodiment of the present invention;

[0028] FIG. 2 illustrates a schematic view of the wing, according to one embodiment of the present invention;

[0029] FIG. 3 illustrates a schematic view of the Clearance link and the Lock link, according to one embodiment of the present invention;

[0030] FIG. 4 illustrates a Pin, according to one embodiment of the present invention;

[0031] FIG. 5 illustrates a marine anti-fouling device, according to another embodiment of the present invention; and

[0032] FIG. 6 illustrates a multilayer assembly of the marine anti-fouling device, according to one embodiment of the present invention.

[0033] Like reference names refer to like parts throughout the several views of the drawings.

DETAILED DESCRIPTION OF THE DRAWINGS

[0034] In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the present invention. It will be apparent, however, to one skilled in the art that the present invention may be practiced without these specific details.

[0035] As used herein, the term ‘plurality’ refers to the presence of more than one of the referenced item and the terms ‘a’, ‘an’, and ‘at least’ do not denote a limitation of quantity, but rather denote the presence of at least one of the referenced item.

[0036] Reference herein to “one embodiment” or “another embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the invention. The appearances of the phrase “in one embodiment” in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. Further, the diagrams representing one or more embodiments of the invention do not inherently indicate any particular order nor imply any limitations in the invention.

[0037] Referring to FIG.1 that illustrates a marine anti-fouling device 10 for removing a marine growth from a structure, according to one embodiment of the present invention. The device 10 comprises a plurality of wings 12, each wing including a flap 12F and at least two wing eyelets 13, a plurality of horizontal 14 and vertical rollers 16 which are adapted to clean the structure by rubbing, a plurality of clearance links 18 and lock links 20, each of the clearance and the lock link is adapted to allow mounting of the horizontal rollers 14 and connecting two adjacent wings 12 and a plurality of pins 22 to allow mounting of the vertical roller 16 and connect the clearance link 18 and the lock link 20 with the wing 12.

[0038] The device 10 moves up and down along the structure by an ocean current force. Due to the up and down movement of the ocean surface water the device also moves up and down and rotates around the structure axis due to the buoyant force of the water. The up-down motion makes the horizontal rollers 14 to rotate and clean the surface of the structure. Similarly the rotation of the device makes the vertical rollers 16 to rub and clean the structure and allows the horizontal rollers 14 to move along the clearance link 18 thereby providing linear motion, such that the horizontal roller 14 changes its cleaning area on the structure. This makes sure that whole of the structure along the length and circumference is cleaned by the device 10.

[0039] In one embodiment of the present invention, a chain link 25 is formed by connecting a first wing 121 with a second wing 122 by two lock links 20 and the second 122 and a third wing 123 by two clearance links 18. This chain link 25 is connected to other similar chain links 25 in a closed chain to form the device 10. The chain link 25 is a part which can be connected to similar chain links using the clearance links 18 and lock links 20 to form a big closed loop thereby making the device 10. The number of chain links 25 to be connected with each other from both sides depends on the dimension of the structure on which the device 10 is to be installed. This gives the device 10 the adaptability to be customized as per the dimension of the structure.

[0040] Referring to FIG.2 that illustrates a schematic view of the wing 12, according to one embodiment of the present invention. The wing 12 is one of the main component of the device 10 which helps the device to rotate and move up and down due to the ocean current when immersed in water. The wing 12 includes a flap 12F and at least two wing eyelets 13 which helps it to connect with other components of the device 10. In one embodiment of the present invention, the flap 12F has an aerofoil cross section. This two wing eyelets 13 are located on the thicker end of the aerofoil at top and bottom, such that the wing 12 can rotate about the axis of the two wing eyelets 13. The vertical roller 16 is mounted between the two wing eyelets 13 using the pin 22.

[0041] Wings 12 are the current facilitators that capture the ocean current energy to set the device 10 in revolving motion about offshore structures. Wings 12 are designed in such a way that when the front face of the flap 12F comes in the way of ocean current it gets open automatically due to upstream force whereas wing 12 on other sides whose backsides are facing to the current automatically get closed. This feature allows device 10 to utilize more current energy compare to fix wing design as net torque acting on device is magnified.

[0042] Referring to FIG. 3 that illustrates a schematic view of the clearance link 18 and the lock link 20, according to one embodiment of the present invention. In one embodiment of the present invention, each of the clearance link 18 and the lock link 20 includes a middle cylindrical portion 24 with two link eyelets 26 at its ends, such that the middle cylindrical portion 24 holds the horizontal roller 14. Horizontal rollers 14 are designed in such a way that they revolve and slide along clearance link 18 and Lock link 20 acting as cleaning member and at least two of the horizontal rollers 14 are always in contact with offshore structure to achieve continuous cleaning action. Vertical rollers 16 just rotate about pin 22 and no clearance is provided to slide freely along pin 22 to give extra strength to the assembly.

[0043] Lock link 20 is horizontal component fixed with pin 22 at the link eyelets 26 and connects two pins 22 disposed on two wings 12 with each other and forms closed structure. Clearance links 18 are provided to give extra strength to the device 10 which holds two pins 22 at its two ends and provide with clearance to revolve about pin 22. This feature allows the device 10 ring to wrap closely with offshore structure every time to ensure continuous cleaning action. The clearance link 18 and the lock link 20 are similar except for the holes of the link eyelets 26. The link eyelets 26 of the clearance link has circular holes while in the lock link 20 the holes are of hexagonal shape. It is to be noted that the shape in not a limitation and other shapes may be used. The shape of the hole of the link eyelet 26 in lock link 20 corresponds with the shape of the both ends 30 (shown in FIG.4) of pin 22, so that the rotation of the lock link 20 is locked and it is not able to rotate about the pin.

[0044] FIG. 4 illustrates the pin 22, according to one embodiment of the present invention. The pin includes a cylindrical middle portion 28 and two ends 30 of hexagonal cross section. The link eyelets 26 of the clearance link 18 which have circular holes are adapted to engage with the pin at the cylindrical middle portion 28, such that it allows rotation of the clearance link 18 about the pin 22. Similarly the link eyelets 26 of the lock link 20 which have hexagonal holes are adapted to engage with the pin at the ends 30 of the pin, such that it locks the rotation of the lock link 20 about the pin 22. The the vertical roller 16 is mounted between the two wing eyelets 13 on the cylindrical middle portion 28 of the pin, such that it can rotate about the pin 22.

[0045] In one embodiment of the present invention, the clearance link 18 eyelets are disposed on two sides of the vertical roller 16 towards inside of the two wing eyelets 13 and the lock link 20 eyelets are disposed on outside of the two wing eyelets 13 with the pin 24 inserted in to secure the connection as shown in FIG.1.

[0046] Referring to FIG. 5, that illustrates a marine anti-fouling device 100, according to another embodiment of the present invention. It is similar to the device 10 of first embodiment as shown in FIG. 1 with only difference that it contains wings 12 on alternate vertical pins 22. The pins 22 which do not have the wings 12 are provided with bush 35 to support other links (18 and 20). Bush 35 is the component which can be part of final assembly as per the design requirement. When no current facilitators are required, the wings 12 may be replaced by the bush 35 to give structural rigidity to the device 100.

[0047] The device 10 is a mechanical solution to prevent biofouling using rubbing action of its horizontal and vertical rollers (14 and 16) with offshore structure. This device 10 may be made of HDPE due to its corrosion resistance, recycling and low-density properties that allows it to float on the sea water. Sea waves induces force on device 10 setting it to continuous reciprocating motion along structure. Wings 12 act as current facilitators that utilize ocean current force to give continuous rotational motion to the device 20. Hence device 10 is the cost efficient and durable solution to combatting and controlling the biofouling.

[0048] Referring to FIG. 6 that illustrates a multilayer assembly 200 of the marine anti-fouling device 10, according to one embodiment of the present invention. This helps in cleaning of long structures where a single device 10 is not sufficient as fouling can be up to 30 meter depth from water surface. In one embodiment of the present invention, the device 10 is adapted to be connected with other similar device 10 using a plurality of flexible connectors 40 with a plurality of floaters 44. Flexible connectors 40 are like ropes which are used to achieve this multilayer structure 200 instead of rigid connectors, since rigid connectors may induce excess mechanical stress on the device 10 that may eventually cause failure. Since the connectors 40 are flexible, it may happen that the connectors collapse and both devices 10 may come close due to ocean force impact, so to eliminate this possibility floaters 44 are provided which are act as separators as well adds to the buoyant force on the device 10. Any number of devices 10 may be added on top of each other using the flexible connectors 40 with the floaters 44 as per the length of the structure.

[0049] The device gives the adaptability of customization, by knowing the diameter of the offshore structure which has to be cleaned of marine fouling, the number of chain links 25 required to make the device 10 may be planned at warehouse only hence takes less time at in-situ installation. Similarly knowing the depth of the cleaning required the number of devices 10, flexible connectors 40 and floaters 44 may also be planned and supplied. This flexibility reduces the installation cost and time.

[0050] Although a particular exemplary embodiment of the invention has been disclosed in detail for illustrative purposes, it will be recognized to those skilled in the art that variations or modifications of the disclosed invention, including the rearrangement in the configurations of the parts, changes in steps and their sequences may be possible. Accordingly, the invention is intended to embrace all such alternatives, modifications and variations as may fall within the spirit and scope of the present invention.

[0051] The foregoing descriptions of specific embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teaching.

[0052] The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the appended description.
,CLAIMS:WE CLAIM:

1. A marine anti-fouling device (10) for removing a marine growth from a structure, comprising:
- a plurality of wings (12), each wing including a flap (12F) and at least two wing eyelets (13);
- a plurality of horizontal (14) and vertical rollers (16) which are adapted to clean the structure by rubbing;
- a plurality of clearance links (18) and lock links (20), each of the clearance and the lock link is adapted to allow mounting of the horizontal rollers (14) and connecting two adjacent wings (12); and
- a plurality of pins (22) to allow mounting of the vertical roller (16) and connect the clearance link (18) and the lock link (20) with the wing (12).

2. The marine anti-fouling device according to claim 1, wherein the device (10) moves up and down along the structure by an ocean current force.

3. The marine anti-fouling device according to claim 1, wherein a chain link (25) is formed by connecting a first wing (121) with a second wing (122) by two lock links (20) and the second wing (122) and a third wing (123) by two clearance links (18).

4. The marine anti-fouling device according to claim 3, wherein the chain link (25) is connected to other similar chain links (25) in a closed chain to form the device (10).

5. The marine anti-fouling device according to claim 1, wherein the flap (12F) has an aerofoil cross section.

6. The marine anti-fouling device according to claim 1, wherein the at least two wing eyelets (13) are located on an edge of the flap (12F) on a top and a bottom portion with common axis.

7. The marine anti-fouling device according to claim 1, wherein the vertical roller (16) is mounted between the two wing eyelets (13) using the pin (22).

8. The marine anti-fouling device according to claim 1, wherein each of the clearance link (18) and the lock link (20) includes a middle cylindrical portion (24) with two link eyelets (26) at its ends, such that the middle cylindrical portion (24) holds the horizontal roller (14).

9. The marine anti-fouling device according to claim 8, wherein the horizontal roller (14) can rotate about its axis and slide along the middle cylindrical portion (24).

10. The marine anti-fouling device according to claim 1, wherein the clearance link (18) eyelets are disposed on two sides of the vertical roller (16) towards inside of the two wing eyelets (13) and the lock link (20) eyelets are disposed on outside of the two wing eyelets (13) with the pin (22) inserted inside to secure the connection.

11. The marine anti-fouling device according to claim 1, wherein the device (10) is adapted to be connected with other similar device (10) using a plurality of flexible connectors (40) with a plurality of floaters (44).

12. The marine anti-fouling device according to claim 11, wherein the floaters (44) keep the devices separated and adds to a buoyant force on the device.