GB2473526A - Sign suitable for subsea structure comprising anti-fouling sign plate marker and frame - Google Patents

Abstract

A sign 1 suitable for use on a subsea structure comprises an antifouling sign plate marker 3, a backing member 4, and a fixing frame 6. The fixing frame 6 attaches to the backing member 4 to secure the perimeter of the antifouling marker 3 between the fixing frame 6 and the backing member 4. The backing member 4, and the fixing frame 6 may be made from thermoplastic materials. The backing member and the fixing frame may be bolted together, preferably with appropriate recesses for housing nuts 9, or these components may be welded together to seal the perimeter of the mount. The sign maybe curved for fixing to pipes etc. Provision may be made for securing the sign to subsea structures including providing magnetic fixing means, apertures to receive fixing bands, clip mountings, etc. A protective cover may be provided over the sign plate marker.

Description

1 Apparatus and Methods for Mounting Antifouling Markers 3 The present invention relates to antifouling markers and in particular apparatus and 4 methods for mounting such antifouling markers.

6 Various different types of articles incorporating visual characters are known, for example 7 signs. The visual characters are typically numerals, letters, words, phrases, sentences or 8 other indicia such as regular or irregular shapes. One particular type of sign is that utilised 9 in aquatic environments such as subsea locations, for marking or providing information about an object located below the surface or on the seabed. Such signs have a particular 11 utility in the oil and gas exploration and production industry. Aquatic organisms such as 12 grasses, algae, barnacles, tube worms, sepula, oysters, ascidia, bryozoa and the like are a 13 particular problem, and can cause fouling of such subsea signs so that the sign becomes 14 illegible.

16 In an effort to overcome these problems, polymeric antifouling silicone based compositions 17 have been developed which resist such aquatic growth, as disclosed for example in British 18 Patent No. 1,307,001 in the name of Kroyer. The antifouling properties of these silicone 19 based compositions are known to be improved by incorporating into the vulcanized silicon 1 rubbers a fluid organic compound. See for example British Patent No. 1,470,465 in the 2 name of the International Paint Company Limited; British Patent No. 1,581,727, European 3 Patent Publication No.0 171 110 and European Patent Publication No. EP 0063388 all in 4 the name Shell Internationale Research Maatschappij B.V.

6 Whilst polymeric antifouling markers are known to function well in terms of resisting 7 aquatic growth, it can be difficult to attach or bond such signs to subsea objects. In order 8 to address this problem US Patent Publication No. 2007/0023959 in the name Movevirgo 9 Limited describes a sign formed from the above-described polymeric antifouling compositions and comprising a backing layer of a Velcro � -type hook and/or loop fastener 11 material. The completed markers can then be attached to an object to be located subsea 12 using a suitable adhesive which bonds with the backing sheet. Within UK Patent 13 Publication No. 2,434,022 in the name Champion Environmental Technologies, there is 14 described an alternative method for mounting such vulcanized silicone rubber based markers. The method comprises the steps of applying an adhesive which is compatible 16 with the antifouling material of the marker to at least one of a surface of the marker and a 17 surface of the object, for example a pipe section. Thereafter, the marker is located on the 18 pipe section such that the adhesive forms a bond between the antifouling material of the 19 marker and the pipe section, thereby mounting the marker on the pipe section.

21 Employing an adhesive to mount polymeric antifouling markers can provide satisfactory 22 results if carried out correctly. However, the success of the bond depends upon the skill 23 and knowledge of the individual carrying out the process. If the methods are not carried 24 out correctly then a weaker than expected bond forms between the marker and the subsea structure which can result in the marker becoming detached from the subsea structure 26 such that the associated information contained on the marker is lost.

28 Adhesives for subsea use are often formed by mixing two components. Incorrect mixing 29 can compromise the effectiveness of the adhesive. Even if correctly mixed, the adhesive has a limited useful period during which it can be applied, which may not be more than 31 thirty or forty minutes. This means that individuals may attempt to use the subsea 32 adhesives at the end of their useful lifetimes, which results in poor adhesion of the subsea 33 markers. The adhesive needs to be carefully applied, with incorrect application resulting in 34 a deficient bond. Furthermore, if the adhesion process is carried out on land then a number of factors have been found to weaken the bond, e.g. heat and humidity.

2 These adhesion issues are exacerbated due to the harsh conditions in which the markers 3 operate. Accessing the subsea structures, e.g. for intervention or maintenance purposes, 4 typically requires the use of divers and/or remotely operated vehicles (ROV5). It is common for the diver or the ROV to come into contact with the marker when trying to read 6 the information carried by the marker. This can act to damage the marker or completely 7 dislodge the marker if not properly bonded with the subsea structure. In practice, it is 8 found that if the edge of a polymeric antifouling marker is damaged then this acts a point of 9 weakness within the marker which can result in further tearing or disintegration of the marker.

12 The subsea structures and markers are also required to be cleaned during their operating 13 lifetimes. Typically this is achieved by the employment of high pressure (5000 psi) water 14 jet cleaning systems. A marker can be damaged by such a process or, if incorrectly bonded, the marker can be dislodged as a result of the jet washing process.

17 One method for using polymeric antifouling signs is to manufacture them in the form of a 18 tag wherein an aperture is formed in the backing substrate of the sign. This tag design 19 allows the sign to be attached to a subsea structure by the employment of a steel wire, or other similar attachment means, which is threaded through an aperture. This method 21 simplifies the attachment process so that less skilled individuals can deploy the signs 22 subsea. However, signs attached in this manner are found to move about the mounting 23 such that when required to be detected at a later date the information, can be hidden from 24 a diver or ROV attempting to locate the sign.

26 As well as being susceptible to in situ damage, it is also found that markers can be 27 damaged during periods of transportation, storage and testing of components upon which 28 the markers are deployed. In addition, a number of materials from which polymeric 29 antifouling markers are manufactured are found to be susceptible to fading when exposed to prolonged periods of sunlight.

32 In order to provide physical protection from damage and exposure to sunlight it is known to 33 provide the polymeric antifouling markers with a protective plastic cover. Although the use 34 of such covers provides protection from dust, grit, weld spatter, UV light and mechanical damage they do not provide an entirely satisfactory solution.

2 Plastic covers require tape to secure them in place and once in place they can act to 3 obscure the information contained on the marker. Over time tape is known to lose 4 adhesion thus resulting in the plastic covers becoming detached from the markers. This reduced adhesion is exacerbated during periods of testing of components upon which the 6 markers are deployed since the plastic covers are often required to be repeatedly removed 7 during these test processes. Furthermore, it is found that the removal of adhesive tapes 8 can also directly damage the substrates upon which the markers are located. Once these 9 substrates are damaged there is a tendency for the plastic covers to be left off thus leaving the markers again susceptible to fading from sunlight.

12 Obscuring the information contained on the marker can lead to the incorrect components 13 being selected from storage for transportation and/or deployment. It is therefore 14 inconvenient, and in some circumstances costly, to have to replace such incorrectly selected components.

17 It is therefore an object of an aspect of the present invention to obviate or at least mitigate 18 the foregoing disadvantages of the prior art methods and apparatus employed for 19 mounting antifouling markers and in particular polymeric antifouling markers on subsea structures.

22 Summary of Invention

24 According to a first aspect of the present invention there is provided a sign suitable for use on a subsea structure, the sign comprising a antifouling marker, a backing member, and a 26 fixing frame wherein the fixing frame is attached to the backing member so as to secure at 27 least one perimeter section of the antifouling marker between the fixing frame and the 28 backing member.

Preferably the antifouling marker comprises a polymeric antifouling marker.

32 The fixing frame may surround the full perimeter of the polymeric antifouling marker so as 33 to secure the full perimeter between the fixing frame and the backing member. In such an 34 embodiment the internal area of the fixing frame is preferably smaller than a surface area of the polymeric antifouling marker.

2 The backing member may be a backing panel.

4 Optionally the sign further comprises a frame located between the backing panel and the fixing frame and which surrounds at least one perimeter section of the polymeric 6 antifouling marker. Preferably the frame locates around the entire perimeter of the 7 polymeric antifouling marker.

9 Most preferably the backing member and the fixing frame comprise a thermoplastic material.

12 Optionally the thermoplastic material comprise a thermoplastic material selected from the 13 group comprising polypropylene, polyethylene, PVC, UPVC, acrylic, hypalon, 14 polycarbonate, polyisobutene, polystyrene and PVDF.

16 The fixing frame and the backing panel may comprise one or more apertures suitable for 17 receiving a securing bolt. Preferably the backing plate comprises one or more recesses 18 suitable for housing a nut for the securing bolt.

In one embodiment the backing panel comprises a clip mechanism that provides a means 21 for attaching the sign to a subsea structure.

23 Optionally the sign further comprises a mesh and a base frame wherein the base frame is 24 attached to the backing panel so as to locate the mesh between the base frame and the backing panel. Preferably the sign further comprises a cover attachable with the fixing 26 frame so as to provide physical protection to the polymeric antifouling marker.

28 In alternative embodiment the sign further comprises a magnetic backing plate attached to 29 the backing panel. The magnetic backing plate preferable comprises a push form plate and a flexible magnetic strip whereby when the magnetic backing plate is attached to the 31 backing panel the flexible magnetic strip takes on the profile of the push form plate.

33 Optionally the magnetic backing plate further comprises a base frame. Preferably the 34 base frame comprises one or more recesses suitable for housing a nut for the securing bolt.

2 In some embodiments the polymeric antifouling marker, the backing panel, and the fixing 3 frame are curved. In such embodiments the signs are suitable for deployment with a 4 cylindrical subsea structure.

6 The sign may further comprise a cradle mounting attached to the backing panel so as to 7 define one or more tunnels suitable for receiving a fixing means for the sign. Preferably 8 the cradle mounting comprises two or more support bars. Optionally the cradle mounting 9 further comprises a cradle plate attached to the support bars so as to locate the support bars between the cradle plate and the backing panel.

12 Optionally the sign may further comprise a saddle mount attached to the backing panel so 13 as to define one or more tunnels having a predefined radius of curvature and suitable for 14 receiving a fixing means for the sign. Preferably the saddle mount comprises at least one curved banding support struts located between two sign support struts wherein the height 16 of the curved banding support strut is less than the height of the two sign support struts.

18 In an alternative embodiment the backing member comprises a backing frame. In such 19 embodiments attachment of the fixing frame to backing frame allows for both two sides of the polymeric antifouling marker to remain visible. Preferably the backing frame and the 21 fixing frame comprise an aperture suitable for receiving a steel tie. In this embodiment the 22 sign can be used as a tag having information presented on both sides of the marker.

24 In a further alternative embodiment the surface area of the backing panel is greater than the area covered by the fixing frame. The backing panel may therefore comprise one or 26 more apertures suitable for receiving banding fixing means. Such an embodiment 27 provides a sign that is particularly suited for use with a grating.

29 Optionally the backing panel and the fixing frame each comprise two apertures through which banding fixing means may be threaded. Alternatively the backing panel comprises 31 one or more channels through which banding fixing means may be threaded. These 32 embodiments provide a sign that is particularly suited for use with a subsea hose.

34 The sign may further comprise a stand-off mounting attached to the backing panel wherein the stand-off mounting comprises two or more standoff runs which are arranged to define 1 a channel on the lower surface of the sign. When such signs are attached to a subsea 2 structure the channels provide a means for water to freely move under the sign.

4 Optionally the sign further comprises a sliding cover guide attached to the fixing frame so as to provide a guide channel between the sliding cover guide and the fixing frame.

7 Most preferably the sign further comprises a protective cover that forms a physical barrier 8 for the polymeric antifouling marker when located within the guide channel.

Preferably the protective cover provides an interference fitting with the sliding cover frame 11 when located within the guide channel.

13 Optionally a mechanical and/or magnetic clip is employed to secure the protective cover 14 within the guide channel.

16 Optionally at least one outer surface of the protective cover comprises replica information 17 to that contained on the polymeric antifouling marker.

19 According to a second aspect of the present invention there is provided a sign suitable for use on a subsea structure, the sign comprising an antifouling marker, a backing member, 21 and a fixing frame wherein the fixing frame is welded to the backing panel so as to secure 22 at least one perimeter section of the antifouling marker between the fixing frame and the 23 backing member.

Preferably the fixing frame is heat welded to the backing member.

27 Embodiments of the second aspect of the invention may comprise preferred or optional 28 features of the first aspect of the invention or vice versa.

According to a third aspect of the present invention there is provided a sign suitable for 31 use on a subsea structure, the sign comprising an antifouling marker and a water jet cut 32 backing member and fixing frame wherein the fixing frame is attached to the backing panel 33 so as to secure at least one perimeter section of the antifouling marker between the fixing 34 frame and the backing member.

1 Preferably the fixing frame is attached to the backing member by welding. Most preferably 2 the fixing frame is heat welded to the backing panel.

4 Embodiments of the third aspect of the invention may comprise preferred or optional features of the first or second aspects of the invention or vice versa.

7 According to a fourth aspect of the present invention there is provided a method of 8 producing a sign suitable for use on a subsea structure, the method comprising the steps 9 of -providing an antifouling marker; 11 -providing a backing member and a fixing frame; and 12 -attaching the fixing frame to the backing member so as to secure at least one perimeter 13 section of the antifouling marker between the fixing frame and the backing panel.

Preferably the antifouling marker comprises a polymeric antifouling marker.

17 Most preferably the step of providing the backing member and the fixing frame comprises 18 water jet cutting a thermoplastic material.

Preferably the step of attaching the fixing frame to the backing member comprises welding 21 and most preferably heat welding.

23 Optionally the method further comprises the step of bonding the polymeric antifouling 24 marker to the backing member 26 Preferably the method further comprises the step of attaching the backing member to a 27 mount.

29 Preferably the method further comprises the step of attaching a sliding cover guide to the fixing frame so as to define a guide channel suitable for receiving a protective cover.

32 Optionally the method further comprises the step of locating a protective cover within the 33 guide channel. The protective cover may be provided with replica information to that 34 contained on the polymeric antifouling marker.

1 Embodiments of the fourth aspect of the invention may comprise preferred or optional 2 features of the first, second or third aspects of the invention or vice versa.

4 According to a fifth aspect of the present invention there is provided a method of producing a sign suitable for use on a subsea structure, the method comprising the steps of 6 -providing an antifouling marker; 7 -providing a backing member and a fixing frame; and 8 -welding the fixing frame to the backing member so as to secure at least one perimeter 9 section of the polymeric antifouling marker between the fixing frame and the backing panel.

12 Embodiments of the fifth aspect of the invention may comprise preferred or optional 13 features of the fourth aspect of the invention or vice versa.

According to a sixth aspect of the present invention there is provided a method of 16 producing a sign suitable for use on a subsea structure, the method comprising the steps 17 of 18 -providing an antifouling marker; 19 -water jet cutting a backing member and a fixing frame; and -attaching the fixing frame to the backing member so as to secure at least one perimeter 21 section of the polymeric antifouling marker between the fixing frame and the backing 22 panel.

24 Embodiments of the sixth aspect of the invention may comprise preferred or optional features of the fourth or fifth aspects of the invention or vice versa.

27 Brief Description of Drawings

29 Aspects and advantages of the present invention will become apparent upon reading the following detailed description and upon reference to the following drawings in which: 32 Figure 1 presents: 33 (a) an exploded side view; 34 (b) a schematic assembled perspective view; and (c) a schematic assembled front view with cut away section 1 of a sign in accordance with an embodiment of the present invention; 3 Figure 2 presents: 4 (a) a schematic assembled side view; (b) an exploded view; and 6 (c) an assembled front view 7 of a sign in accordance with an alternative embodiment of the present invention; 9 Figure 3 presents: (a) an exploded view; and 11 (b) a schematic assembled view 12 of the sign of Figure 2 having a clip mount; 14 Figure 4 presents: (a) an exploded view; 16 (b) a schematic assembled side view; and 17 (c) an assembled front view 18 of a mimic sign in accordance with an embodiment of the present invention; Figure 5 presents: 21 (a) an exploded view; 22 (b) a first schematic view; 23 (c) a second schematic view; 24 (d) a schematic view in situ; and (e) a side view in situ 26 of a sign having a backing panel suitable for mounting on a concrete block; 28 Figure 6 presents: 29 (a) an exploded view; (b) a schematic side view; 31 (c) a schematic lower view; and 32 (d) a side view 33 of a sign having a magnetic backing panel; Figure 7 presents: 1 (a) an exploded view; 2 (b) a first schematic side view; and 3 (c) a second schematic side view 4 of a curved sign having a cradle mounting; 6 Figure 8 presents: 7 (a) an exploded view; 8 (b) a schematic lower view; and 9 (c) a schematic side view of a flat sign having a cradle mounting; 12 Figure 9 presents: 13 (a) an exploded view; 14 (b) a first schematic side view; and (c) a second schematic side view 16 of a flat sign having a cradle and saddle mounting; 18 Figure 10 presents: 19 (a) an exploded view; and (b) a schematic assembled side view 21 of a tag sign in accordance with an embodiment of the present invention; 23 Figure 11 presents: 24 (a) an exploded view; (b) a schematic assembled side view; and 26 (c) a front assembled view 27 of a sign having a backing panel suitable for mounting onto grating; 29 Figure 12 presents: (a) an exploded view; and 31 (b) a schematic assembled side view 32 of a sign having a backing panel suitable for mounting on a hose; 34 Figure 13 presents: (a) an exploded view; and 1 (b) a schematic assembled side view 2 of a sign having an alternative backing panel suitable for mounting on a hose; 4 Figure 14 presents: (a) an exploded view; 6 (b) a first schematic side view; and 7 (c) a second schematic side view 8 of a flat sign having a cradle and stand-off mounting; Figure 15 presents: 11 (a) an exploded view; and 12 (b) a side assembled side view 13 of a flat sign having a cradle and a saddle with an integrated stand-off mounting; and Figure 16 presents: 16 (a) an exploded view; and 17 (b) a schematic assembled view 18 of the sign of Figure 2 having a sliding cover frame.

Detailed Description

22 Figure 1(a) presents an exploded side view of a sign 1 in accordance with an embodiment 23 of the present invention which comprises a mount 2 within which is housed a polymeric 24 antifouling marker 3.

26 The mount 2 can be seen to comprise a backing member 4 in the form of a panel, an inner 27 frame 5 and a fixing frame 6. The internal area of the inner frame 5 corresponds to the 28 surface area of the polymeric antifouling marker 3 while the internal area of the fixing 29 frame 6 is smaller than the surface area of the polymeric antifouling marker 3. Each of the backing panel 4, the inner frame 5 and fixing frame 6 can be seen to comprise four 31 apertures 7 suitable for receiving bolts 8. Nuts 9 can then be employed in order to secure 32 the sign 1 on a subsea structure, further details of which are described below.

34 The backing panel 4, the inner frame 5 and the fixing frame 6 are preferably made from a thermoplastic material. Some thermoplastic materials are known to be difficult to bond, for 1 example polyethylene and polypropylene. However, thermoplastic materials are known to 2 melt under the application of heat and set when cooled. The cooled material has the same 3 properties as it had prior to melting and so these materials can be melted and cooled over 4 a number of occasions.

6 The following is a list of suitable thermal plastic materials along with their associated 7 welding temperatures that can be employed to produce the mount 2, namely: 9 Polypropylene (-300°C) Polyethylene (250 to 300°C) 11 PVC/UPVC (-300°C) 12 Acrylic (-350°C) 13 Hypalon (-V 600°C) 14 Polycarbonate (-350°C) Polyisobutene (-600°C) 16 Polystyrene (-250°C) 17 PVDF (-350°C) 19 From the above listed materials, the preferred option is to use polyethylene since this material is known to have inherent anti-fouling properties.

22 There exist a number of means for applying the heat required to weld the thermoplastic 23 materials. In the first instance, a hot air gun may be used. For hot air welding of 24 polyethylene the material requires to be cleaned with a solvent such as IPA so as to remove any greases or dust which may interfere with the bond. The heating times will 26 depend on the particular thermoplastic being employed and the size of the components 27 being welded. In practice, it is found that small sections can be heat welded in a few 28 seconds while larger elements take tens of seconds to reach the required welding 29 temperatures.

31 Alternatively, the heat could be provided by means of ultrasonic vibration wherein 32 ultrasonic energy is focused through a horn on to the area to be welded. The ultrasonic 33 energy acts to heat and melt the plastic and bonding occurs when cooled. Further 34 alternatives comprise the use of microwave welding focused in a similar manner to 1 ultrasonic energy or friction welding which vibrates two surfaces together at high speeds 2 so as to produce the required heat.

4 Cooling times are also found to vary depending on the particular thermoplastic materials.

Generally the more heat required to melt the thermal plastic the longer it will take to cool.

6 The components to be heat welded may be clamped prior to the operation being carried 7 out and thereafter left in place until cooled. Typically cooling in air may take 5 to 6 8 minutes. Alternative cooling methods, such as the employment of a cooling mist or a 9 cooling bath may be used to speed up the cooling process and allow for a more automated high volume process be adopted.

12 The sign 1 as shown in Figure 1(b) is assembled as follows. In the first instance the 13 polymeric anti-fouling marker 3 is located in position on to the backing panel 4. Use of an 14 adhesive bond to assist in locating the marker 3 and to secure the marker is preferred.

Next the inner frame 5 is position around the polymeric antifouling marker 3. The fixing 16 frame 6 is then positioned over the marker 3 and the inner frame 5. The final step involves 17 securing the positions of the backing panel 4, the innerframe Sand the fixing frame 6.

18 Preferably this is achieved by heat welding around the perimeter of the mount although 19 alternative welding techniques or indeed mechanical fixing means such as clamps or clips could also be employed.

22 Figure 1(c) presents a schematic view of the assembled sign 1 with a lower cut away 23 section. Here it can be clearly seen that because the internal area of the fixing frame 6 is 24 less than the surface area of the polymeric anti-fouling marker 3 then the fixing frame overlaps a perimeter section of the polymeric anti-fouling marker 3. In this way the 26 polymeric anti-fouling marker 3 is fixed in position within the mount 2 and the mount 2 can 27 then be attached to a subsea structure by a number of mechanical means, as described in 28 further detail below. Incorporating the polymeric anti-fouling marker 3 within the mount 2 29 therefore removes the need for the polymeric anti-fouling marker 3 to be bonded directly to the subsea structure.

32 By the nature of the industry, the polymeric anti-fouling markers 3 and hence the 33 associated mounts 2 are required to be made in a large variety of shapes and thicknesses.

34 As a result bespoke signs 1 are made to order based on the requirements of the customer.

For this reason it is necessary to have a highly adaptable means for machining the 1 thermoplastic materials i.e. the backing panel 4, the inner frame 5 and the fixing frame 6.

2 The most efficient and reliable way for machining these components found by the 3 inventors, which provides the required flexibility for producing the bespoke component 4 parts, is to employ water jet cutting techniques.

6 An alternative embodiment of the sign lb is presented in Figure 2(a). In this embodiment 7 the inner frame 5 is replaced by the use of thermoplastic welding rods 10. As can be seen 8 from the exploded view of Figure 2(b) the welding rods 10 are located around the 9 perimeter of the backing panel 4. The polymeric anti-fouling marker 3 is again located on the backing panel 4 and the fixing frame 6 is thereafter positioned on top of the welding 11 rods 10 and the anti-fouling marker 3. The anti-fouling marker 3 is then secured in place 12 by heat welding around the perimeter of the mount 2 so as to seal the interface between 13 the backing panel 4 and the fixing frame 6 thus encapsulating the anti-fouling marker 3 as 14 required, while still allowing for the information carried by the anti-fouling marker 3 to remain visible. From Figure 2(c) it can again be seen that since the internal area of the 16 fixing frame 6 is less than the surface area of the polymeric anti-fouling marker 3 (the 17 perimeter of the polymeric anti-fouling marker 3 being indicated by the dashed line) then 18 fixing frame overlaps a perimeter section of the polymeric anti-fouling marker 3, thereby 19 securing the marker 3 within the mount 2.

21 Figure 3 presents an alternative embodiment of the sign 1 of Figure 1. In this embodiment 22 the sign 1 further comprises a clip mechanism 11 that allows for the sign 1 to be easily 23 attached to a riser or other similar cylindrical structure 12. In this embodiment it is 24 preferable for a neoprene liner 13 to be located within the clip mechanism 11 before it is attached to the cylindrical structure by means of bolts 8 threaded through apertures 7 26 located within the body of the clip 11.

28 The flexibility and scalability of the presently described methods and apparatus will now 29 described with reference to Figure 4 which presents an exploded view, a schematic assembled perspective view and an assembled front view of a mimic sign lb in 31 accordance with an embodiment of the present invention. In this embodiment the sign lb 32 comprises an antifouling marker 3 that is again located on the backing panel 4. The 33 antifouling marker 3 and the backing panel 4 are both water jet cut so as to contain various 34 geometrically shaped apertures 14 so as to provide a mimic of the structure to which the sign lb is to be attached. The sign lb is assembled as previously described with the 1 antifouling marker 3 being bonded to the backing panel 4, the fixing frame 6 being located 2 over the antifouling marker 3 with the inner perimeter area of the fixing frame 6 being 3 smaller than the surface area of the antifouling marker 3. The components are then heat 4 welded in the order to provide a sealed single piece unit. The dash line presented in Figure 4(c) shows the outer perimeter of the antifouling marker 3 so as to again highlight 6 the fact that the fixing frame 6 acts to secure the antifouling marker 3 in place within the 7 mount 2.

9 Figure 5 presents an alternative sign 1 b that comprises additional elements so as to make the sign lb suitable for mounting on a concrete block 15. In particular Figures 5 (a)to (e) 11 present respectively an exploded view, a first schematic assembled view, a second 12 schematic assembled view, a schematic view of the sign in situ and a side view of the sign 13 in situ, respectively. The sign lb can be seen to comprise a backing panel 4, a polymeric 14 anti-fouling marker 3 and a fixing frame 6 as previously described. In addition the sign lb comprises a temporary cover 16, a mesh 17 and a base frame 18.

17 The components are arranged such that the mesh 17 is located between the base frame 18 18 and the backing panel 4. The polymeric anti-fouling marker 3 is again bonded to the 19 backing panel 4 before the fixing frame 6 is positioned on top. A number of securing bolts 8 are then threaded through the apertures 7 located in the fixing frame 6, the backing 21 panel 4 and the base frame 18 so as to secure the components together. Welding rods 10 22 are again employed to seal the perimeter of the mount 2 via a heat welding process which 23 also acts to weld the backing panel 4 and the base frame 18. Once assembled, the cover 24 16 is attached to the fixing frame 6 by screws 19 so as to provide a physical barrier for the polymeric anti-fouling marker 3. With the cover 16 SO located, concrete can be poured, as 26 appropriate, so as to fix the sign 1 in the desired location. Since the base frame 18 allows 27 access to the underside of the sign 1 b it allows for the concrete to flow so as to embed the 28 mesh 17, the nuts 9 for the securing bolts 8 and the base frame 18, as shown in Figure 29 5(e).

31 Figure 6 presents various views of a sign lb comprising a magnetic backing plate 20 that 32 provides the means for attachment of the sign lb to a subsea structure. As can be seen 33 from the exploded view presented in Figure 6(a) the magnetic backing plate 20 comprises 34 a push form plate 21, a flexible magnetic strip 22 and a base frame 18. Figure 6(a) also shows the positioning of welding rods 10 on the push form plate 21 and the base frame 18.

1 Assembly of the device is as follows: the flexible magnetic strip 22 is threaded through 2 rectangular shaped apertures 23 located within the push form plate 21 so that the 3 magnetic strip 22 takes on the profile of the push form plate 21. The flexible magnetic strip 4 22 is then bonded to the backing panel 4 while the push form plate 21 is heat welded to the backing panel 4. The base frame 18 is then located over the flexible magnetic strip 22 6 and heat welded in place so as to provide a clamping force for the magnetic strip 22. The 7 device may be further secured by the use of the securing bolts 8. The nuts 9 for the 8 securing bolts 8 are located within recesses located within the base frame 18 so as to 9 provide the device with a substantially planer lower surface. This assists in the magnetic fixing of the sign lb to a subsea structure 12.

12 Figure 7(a) to (c) present an exploded view and two schematic assembled side views, 13 respectively, of a curved sign Ic comprising a cradle mounting 24. The sign ic comprises 14 a curved backing panel 4c and two curved fixing bars 25 which act to clamp the anti-fouling marker 3c in position upon the backing panel 4c, in a similar manner to that 16 previously described. The cradle mounting 24 comprises four curved support bars 26 that 17 are arranged on the lower surface of the backing panel 4c and curved cradle plate 27, that 18 supports a plurality of curved welding rods lOc. The curved welding rods lOc are heat 19 welded in order to attach the curved cradle plate 27 and the curved support bars 26 to the backing panel 4c, as shown in Figures 7(b) and (c). This arrangement results in cradle 21 mounting 24 providing three curved tunnels 28 through which banding 29 can be threaded 22 so as to secure the cradle mounting 24, and hence the sign 1 c in place to a curved subsea 23 structure 12, as shown schematically in Figure 7(c).

It will be appreciated by those skilled in the art that the cradle mounting 24 need not have 26 a curved profile. Indeed Figure 8 presents a sign 1 that incorporates a flat cradle mounting 27 30. In this embodiment planar support bars 31 are heat welded to the backing panel 4.

28 Thereafter, a flat cradle plate 32 is heat welded to the support blocks 31 so as to provide 29 the mount 2 with two tunnels 28 suitable for banding 29 that provides a means for fixing the sign 1 to a subsea structure. Securing bolts 8 and nuts 9 may again be employed to 31 provide further strength to the structure. The nuts 9 are again located within recesses 32 formed on the underside of the flat cradle plate 32 so as to provide the structure with a 33 substantially flat surface lower surface.

1 During deployment it is found that sharp 9Q0 edges, such as those found within the 2 structure present in Figure 8, can put undue stresses on the banding 29 employed to fix 3 the sign 1 in place. As a result the banding 29 can snap and therefore the sign 1 could 4 become detached from the subsea structure. In order to mitigate the effects of these sharp edges, a saddle mount 33 as presented in an exploded view within Figure 9(a) and 6 is shown being employed to attach a sign 1 to a subsea structure 12 within Figures (9b) 7 and (c).

9 In the presently described embodiment the saddle mount 33 comprises two curved banding support struts 34 and three sign support struts 35. The lower surfaces of the 11 curved banding support struts 34 and the sign support struts 35 are water jet cut so as to 12 match the specific radius of the subsea structure 12 to which the saddle mount 33 and 13 hence the sign 1, is to be attached. As can be seen the banding support struts 34 are 14 located between adjacent sign support struts 35 and these components are secured together by two bolts 8 and nuts 9.

17 Significantly the height of the banding support struts 34 is less than the height of the sign 18 support struts 35 such that they form two tunnels 28 through which banding 29 can be 19 threaded so as to secure the device in place. When the banding 29 is threaded through these tunnels 28 extending legs 36 of the banding supports 34 provide for a gentler radius 21 for the banding 29 and so reduces the stress experienced by the banding 29 when in-situ.

22 By employing the saddle mount 33 the lifetime which the sign 1 can be expected to remain 23 in place with the subsea structure 12 is significantly increased.

Figure 10 presents an alternative embodiment of the sign id. In this embodiment the sign 26 1 d is in the form of a tag, an exploded view and a schematic side view for which are 27 presented in Figure 10(a) and (b), respectively.

29 In this embodiment, the tag mount 37 comprises a fixing frame 6, a backing member 4 in the form of a frame, and a polymeric antifouling marker 3. Significantly, the internal area 31 of the tag mount 37 is less than the surface area of the polymeric antifouling marker 3. To 32 assemble the tag Error! Bookmark not defined.d frames 4 and 6 are located around the 33 polymeric antifouling marker 3 and are then heat welded in place by means of welding 34 rods 10. In this way the polymeric antifouling marker 3 is secured within the tag mount 37.

Once welded, a cable-tie 38 can be threaded through an aperture 39 in the tag mount 37 1 so as to provide a means for attachment to a subsea structure. The cable-tie may be 2 made of steel, nylon or other suitable material 38.

4 The tag id exhibits several advantages over those described in the prior art. In the first instance the polymeric antifouling marker 3 can be provided with information located on 6 both sides. Thus when deployed, if the tag id were to rotate about the steel tie 38 fixing 7 means then the required information would still be visible to the diver or ROV operator.

8 This is a more cost effective solution to providing two separate polymeric antifouling 9 markers 3 mounted on opposite sides of a central plate since it is the production of the polymeric antifouling marker 3 that is the most expensive component of the device.

12 Figures 11(a) to (c) respectively present an exploded view, a schematic assembled 13 perspective view and a front view of a sign 1 having a backing panel 40 suitable for 14 attachment to a grating 41. In this embodiment the backing panel 40 comprises a recess 42 for locating the polymeric antifouling marker 3 and a plurality of apertures 43 suitable 16 for receiving cable tie 38 fixing means. The fixing frame 6 is again located over the 17 polymeric antifouling marker 3 and heat welded in place, in a similar manner to that 18 previously described. The backing panel 40 can then be located against the grating 41 as 19 shown in Figure 11(b) and fixed in place by cable tie 38 fixing means. Such a sign is suitable for location on a manifold roof where ROVs are frequently required to land and 21 therefore are known to cause damage to signs place in such locations.

23 With reference to Figure 12 a sign le suitable for mounting on a hose 44 will now be 24 described. In particular, Figures 12 (a) and (b) respectively present an exploded view and a schematic assembled side view of the sign. In a similar manner to that described 26 previously, the polymeric antifouling marker 3 is bonded to the backing panel 45 which in 27 this embodiment comprises two apertures 46 located at either end that are suitable for 28 receiving a banding 29 fixing means. The backing panel 45 further comprises welding 29 rods 10 located around its perimeter.

31 A fixing frame 47, having internal area that is smaller than the surface area of the 32 polymeric antifouling marker 3, is then located over the polymeric antifouling marker 3.

33 The fixing frame 47 also has two apertures 46 located at either end that are also suitable 34 for receiving a banding 29 fixing means. The sign le is then heat welded around its perimeter so securing the polymeric antifouling marker 3 therein. As shown in Figure 1 12(b) banding fixing means can then be threaded through the apertures 46 so as to 2 provide a means for fixing the 1 e to a hose 44.

4 An alternative embodiment of a sign if suitable for mounting on a hose 44 is presented in Figure 13. In this embodiment the backing panel 45b has channels 48 provided within the 6 welding rods 10 so as to provide a channel that allows a cable tie or banding 29 fixing 7 means to be threaded through the sign if so as to provide the means for fixing the sign if 8 to the hose 44. In practice it is found to be simpler to deploy the signs shown in Figure 13 9 than those described in relation to Figure 12 since the threading of the banding fixing means does not require the same level of manual dexterity.

12 Figure 14 presents an alternative embodiment of the sign 1 incorporating the cradle 13 mounting 30, as described previously with reference to Figure 8, which further comprises a 14 stand-off mounting 49. From the exploded view of Figure 14(a) the stand-off mounting 49 can be seen to five standoff runs 50 which are attached to the lower surface of the flat 16 cradle plate 32 so as to form four equally sized channels 51. In this way, when the sign 1 17 is attached to a subsea structure, the channels 51 provide a means for water to freely 18 move under the sign. As can be seen from the view presented in Figure 14(c), 19 approximately 70% of the lower surface of the flat cradle plate 32 remains open. This is advantageous since allowing the water to move freely underneath the sign reduces the 21 presence of stagnant water under the sign, so reducing the effects of corrosion and 22 thereby increasing the lifetime of the device.

24 Figures 15 (a) and (b) present an exploded view and an end assembled view, respectively, of an alternative saddle mount 33b to that previously described with reference to Figure 9.

26 Saddle mount 33b differs from that previously described in that it further comprises an 27 integrated stand-off mounting in the form of three channels 51 being formed on the 28 underside of each of the sign support struts 35b. Thus, when the sign 1 is attached to a 29 subsea structure, the channels 51 provide a means for water to freely move under the sign thus reducing the effects of corrosion.

32 Figure 16 presents an exploded view of the sign lb of Figure 2 further comprising a sliding 33 cover frame 52 while Figure 16(b) presents a schematic assembled view of this 34 embodiment. In particular, the sign lb can to further comprise a three sided, sliding cover frame 52 that is welded by way of welding rods 10 to the top surface of the fixing frame 6.

1 The lower side of sliding cover frame 52 thus forms a guide channel 53 with the top 2 surface of the fixing frame 6 suitable for receiving a protective cover 54. The protective 3 cover 54 forms an interference fit with the guide channel 53 so as to secure it in place for 4 periods of transportation and/or storage. A mechanical or magnetic clip (not shown) may also be employed to further assist in securing the protective cover 54 within the guide 6 channel 53.

8 The use of the sliding cover frame 52 and the protective cover 54 provides a physical 9 barrier for the polymeric antifouling marker 3 so as to protect it from accidental damage and UV light during periods of transportation and/or storage. Employing these 11 components also removes the requirement for tape to be employed to secure a plastic 12 cover over the polymeric antifouling marker 3. The protective cover 54 may further 13 comprise replica information to that contained on the polymeric antifouling marker 3 14 printed on its outer surfaces. In this way the protective covers 54 also address the disadvantage of information on the polymeric antifouling marker 3 being obscured when 16 plastic covers are deployed.

18 The presently described signs offer a number of advantageous over those known in the 19 art. In the first instance the locating the polymeric antifouling marker within a mount comprising a fixing frame and a baking panel provides for significant simplification for the 21 methods of mounting the sign on a subsea structure. In particular the reliance on the use 22 of adhesives to bond the polymeric antifouling markers is removed and so the attachment 23 of such markers does not require the same degree of skill. As a result the signs can be 24 more reliably attached without the experience of subsea adhesive techniques.

26 By employing thermoplastic materials to form the mounts allows for welding techniques to 27 be employed so as to seal the perimeter of the mounts. As a result the likelihood of 28 physical damage to the polymeric antifouling markers through the ingress of water, due to 29 collision with divers or ROVs or through the impact of high pressure water cleaning is significantly reduced.

32 Thermoplastic materials also lend themselves to efficient water jet cutting. This allows for 33 bespoke signs to be easily produced, as and when required by a customer.

1 The foregoing description of the invention has been presented for purposes of illustration 2 and description and is not intended to be exhaustive or to limit the invention to the precise 3 form disclosed. The described embodiments were chosen and described in order to best 4 explain the principles of the invention and its practical application to thereby enable others skilled in the art to best utilise the invention in various embodiments and with various 6 modifications as are suited to the particular use contemplated. Therefore, further 7 modifications or improvements may be incorporated without departing from the scope of 8 the invention as defined by the appended claims.