Field of the Invention

[0001] The present invention relates to apparatus for servicing a structure, such as a support structure including but not limited to marine support structures such as risers, conductors, caissons, piles, or legs for marine platforms, jetties or wharves, or pipes, and land-based or offshore structures such as wind turbine towers.

Background of the Invention

[0002] Marine support structures typically suffer from ageing and degradation, particularly in the 'splash zone', which is the part of the structure that is periodically covered and uncovered by water, for example as a result of tidal range, wave action and/or splashing. Ageing may include corrosion and physical damage caused by wave action and impacts. Degradation may include accumulation of marine growth, such as weed, barnacles etc.

[0003] Marine support structures therefore need to be serviced, for example by cleaning, inspection, and coating or painting, to ensure continued performance and to extend their life. Conventionally, servicing is carried out by divers but this can be extremely difficult and hazardous, particularly in the splash zone, and is often not fully effective. Land-based or offshore structures such as wind turbine towers also require maintenance and may not be easily accessible, whether due to their height or their location.

[0004] WO-A-2020/096529 discloses apparatus for servicing a structure, comprising a frame for assembly around the structure, with pairs of arms extending in axially opposite directions, each carrying a wheel or roller for driving and/or supporting the frame against the structure.

[0005] For some applications, there is a need to provide a smaller and/or lighter apparatus of the above type, which can be more easily moved into position around the structure to be serviced. Preferably, the apparatus should be able to pass small obstructions on the structure. It would be also desirable to be able to quickly release the apparatus from the structure in an emergency.

Summary

[0006] Aspects of the invention comprise apparatus for servicing a structure, comprising a frame for assembly around the structure, a plurality of rotatable members mounted on the frame and arranged to contact the structure so as to allow the frame to be driven along the structure; and a tool carriage connected to the frame and arranged to carry one or more tools for servicing the structure.

[0007] According to one embodiment, upper and lower rotatable members are mounted on a bracket that is able to pivot relative to the frame so that one of the rotatable members is able to ride over an obstruction while the other rotatable member stays in contact with the structure to be serviced. The pivoting bracket is mounted so as to pivot about a rotational axis of the rotatable member that stays in contact with the structure. This provides a simple arrangement for overcoming obstacles on the structure.

[0008] According to another embodiment, the frame comprises at least first and second frame sections that are separable at respective free ends thereof to enable the frame to be arranged around the structure, the free ends being connectable together by a latching mechanism that is operable to adjust the tension of the connection between the free ends, the latching mechanism including a quick release mechanism for releasing the connection between the free ends. This may allow the frame to be quickly removed from the structure in the case of an emergency.

[0009] The latching mechanism may include a first connector connected to the free end of the first frame section and a second connector connected to the free end of the second frame section, the first and second connector being adjustably connected together so as to adjust the connection between the free ends, wherein the quick release mechanism is arranged to disconnect one of the first and second connectors from the respective one of the free ends. Brief Description of the Drawings

[0010] Specific embodiments of the present invention will now be described with reference to the accompanying drawings, in which:

Figure 1 is a perspective view from above of an apparatus in an embodiment of the invention;

Figure 2 is a top view of the apparatus of the embodiment;

Figure 3 is a perspective view of a wheel mounting arrangement in the embodiment;

Figures 4-6 are side views of the wheel mounting arrangement in different pivotal positions; Figure 7 is a perspective view of frame parts of the apparatus of the embodiment, with a latching mechanism;

Figure 8 is a top view of the parts of Figure 7;

Figure 9 is a top view showing the latching mechanism in more detail.

Detailed Description of Embodiments

[0011] In the description below, the orientation of the apparatus will be described as assembled around a vertically elongate support structure 30. 'Circumferential' and 'tangential' refers to a circumference around a notional central vertical axis, and 'radial' to a direction perpendicular to that axis. However the support structure 30 need not be vertically arranged.

[0012] For clarity, not all instances of a particular part are indicated by reference numerals in the drawings. It will be understood by inspection of the drawings as a whole which parts are referred to. Similar parts between different embodiments are indicated by the same reference numeral.

[0013] Apparatus in an embodiment of the invention is described below with reference to Figures 1 and 2. A cage or frame 1 comprises first and second segments or sections la, lb which are pivotally connected together about a vertical axis at a hinge point 2. This pivotal connection allows the sections la, lb to be opened so as to arrange the frame 1 around the structure 30, and then closed around the structure 30. To secure the frame 1 around the structure 30, free ends la', lb' of the sections la, lb diametrically opposite the hinge point a02 re releasably latched together by a latching mechanism, for example as described in more detail below.

[0014] The frame 1 comprises an upper support 3 and a lower support 4, interconnected by frame struts 5. In this embodiment, the upper and lower supports 3, 4 are approximately circular in shape, and coaxial. The frame struts 5 extend generally vertically between the upper and lower supports 3, 4. The upper support 3, lower support 4 and frame struts 5 are preferably substantially rigid and are connected together so that the frame 1, when assembled, is substantially rigid.

[0015] A guide rail 14 may be connected to and spaced apart from the lower support 4, for example by guide rail struts 16. A tool carriage 15 is drivable circumferentially around the guide rail 14 and is arranged to carry one or more tools 22 for servicing the support structure 30. One or more flexible hoses 23 may be connected between the frame 1 and the tool carriage 15, for example for carrying high-pressure fluid for cleaning.

[0016] By moving the frame 1 up and down the support structure 30 using the driveable wheel(s) 8, 9, and moving the tool carriage 15 circumferentially around the support structure 30, the tool(s) 22 may reach substantially any part of the external surface of the support structure 30, at least within the splash zone and subject to any restrictions due to hoses 23 and the like.

[0017] The tool(s) 22 may be moveably mounted on the carriage 15, to allow movement of the tool(s) 22 relative to the carriage 15. For example, the tool(s) 22 may be reciprocally driveable towards and away from the structure 30, for example in a radial direction.

[0018] Examples of the tool(s) that may be mounted either singly or together on the carriage 15, and which may be interchangeable, include:

- a high-pressure water nozzle for cleaning the surface of the structure 30

- a wall thickness measuring probe for measuring the wall thickness of the structure 30, for example using ultrasound

- a clearance sensor for sensing clearance from the surface of the structure

- a painting tool, such as a paint roller or brushes, for painting the surface of the structure 30

- a wrapping tool for applying a protective wrapping to the structure 30

- a cutting tool for cutting a part of the structure 30, for example using high-pressure abrasive cutting.

[0019] The carriage 15 may carry a camera, such as a video camera, in addition to a cleaning tool 22.

[0020] In an alternative embodiment, the apparatus may comprise a drive module which may be removably connected to one or more further modules that carry tools for servicing the structure 30; in that case the drive module need not include the guide rail 14, tool carriage 15 and tool(s) 22. [0021] The apparatus may include one or more distance sensors, to determine the distance travelled along the support structure 30. The distance sensor(s) may for example determine the number of rotations of the wheel(s) 8, 9, for example by using one or more optical or magnetic angular position sensors.

[0022] The carriage 15 may include one or more rotational position sensors (e.g. optical or magnetic sensors) able to detect an absolute or relative circumferential position of the carriage 15 relative to the frame 1, for example by detecting reference position markings on the guide rail 14.

[0023] The distance sensor(s) and/or rotational position sensors (s) may be used to determine the position of the tool 22, carriage 15 or another part of the apparatus on the support structure 30. This may allow the apparatus to travel to a predetermined absolute position or to return to a previously visited position, for example where an anomaly or discrepancy has been detected.

[0024] The apparatus may be aligned with one or more reference marks on the support structure 30, to allow the apparatus to return to a previously visited position relative to the reference marks.

[0025] Each of the sections la, lb has a wheel support 10 mounted thereon, preferably in a middle part of the section between the hinge point 2 and the free end la', lb' so that the wheel supports 10 are diametrically opposite each other. The wheel support 10 is mounted on the respective section by one or more arms 12, which are preferably adjustable so as to vary the radial position of the wheel support 10 radially inwardly of the frame and thereby adjust the radial position of the wheel support 10 to fit different diameters of structure 30.

[0026] Each wheel support 10 comprises a fixed bracket 11 connected to the arms 12, and a pivotable bracket 13 pivotably mounted relative to the fixed bracket 11, and biased towards a position parallel to the surface of the structure 30. The pivotable bracket 13 may be connected to the fixed bracket 11 by means of a spring 17, which may be adjustable to vary the bias. In the specific embodiment shown, the spring 17 is arranged coaxially with a bolt connected to the fixed bracket 11, with one end of the spring 17 held by a nut at the outer end of the bolt, and the other end of the spring 17 connected to a midpoint of the pivotable bracket 13 so as to bias the pivotable bracket 13 against the fixed bracket 11 in the vertical position shown in Figures 3 and 4. The nut is adjustable in position along the bolt so as to adjust the tension or compression on the spring.

[0027] Upper and lower wheel mounts 18, 19 are provided respectively at upper and lower ends of the pivotable bracket 13, each wheel mount 18, 19 carrying respectively an upper or lower wheel 8, 9 or other rotating member such as a roller. Each wheel 8, 9 may be driven by an associated drive motor, or may rotate without being driven.

[0028] In embodiments designed for support structures 30 of only one diameter, or a small range of diameters, some of the non-driven wheels 8, 9 may be replaced by other types of guides, such as rollers or wheels of fixed radial position.

[0029] At least one of the wheels 8, 9 is driveable reciprocally in either one of opposite directions (e.g. forward and backward) so as to move the frame 1 respectively up and down the support structure 30. Others of the wheels 8, 9 may not be driven but may freely rotate, preferably independently of each other, so as to act as guides for movement of the apparatus up and down the support structure 30.

[0030] As shown in Figures 5 and 6, when one of the wheels 8, 9 encounters an obstacle 20, the pivotable bracket 13 pivots as the wheel 8, 9 passes over the obstacle 20, thus allowing the obstacle 20 to be passed over while maintaining one of the wheels 8, 9 in contact with the structure 30. In the example shown in Figure 5, the frame 1 is driven upwards and the upper wheel 8 passes over an obstacle, with the pivotable bracket 13 pivoting about the rotational axis A2 of the lower wheel 9. In the example shown in Figure 6, the frame 1 is driven downwards and the lower wheel 9 passes over an obstacle 20, with the pivotable bracket 13 pivoting about the rotational axis Al of the upper wheel 8. Hence, the frame 1 may pass over small obstacles 20 on or close to the surface of the structure 30, when driven in either direction. [0031] As illustrated by the example above, the connection between the pivotable bracket 13 and the fixed bracket 11 allows the midpoint of the pivotable bracket to move radially inwardly against the bias of the spring 17, so that the pivotable bracket 13 is able to pivot about the rotational axis Al, A2 of either the upper or lower wheel 8, 9.

[0032] The latching mechanism 40 for securing the free ends la', lb' of the sections la, lb together is shown in Figures 7-9. The latching mechanism 40 comprises a first connector 41 mounted on a first bracket 42 on the free end la' of the first frame section la, and a second connector 43 mounted on a second bracket 44 on the free end lb' of the second frame section lb.

[0033] The connection between the first and second connectors 41, 43 may be adjustable, for example to tighten or slacken the latched connection between the free ends la', lb' of the sections la, lb. In this specific embodiment, the first connector 41 comprises a threaded bolt and the second connector 43 comprises a nut that engages the bolt. The distance of the nut along the bolt may be adjusted by rotating the nut and the bolt relative to one another. In this specific embodiment, the bolt is rotated by a motor 40 which may be controlled remotely.

[0034] The engagement between the first and second connectors 41, 43 may be difficult to release quickly; in the above specific embodiment, the nut and bolt would need to be relatively rotated so that the nut disengages from the bolt. To provide a quick release mechanism, one of the first and second connectors 41, 43 is connected to its respective bracket 42, 44 with a quick release pin 46, removal of which allows the connector 41, 43 to quickly detach from its respective bracket 42, 44 while the first and second connectors 41, 43 remain mutually connected. The quick release mechanism may be used in an emergency to quickly remove the frame 1 from the structure 30. The latching mechanism 40 may later be reset by mutually disconnecting the first and second connectors 41, 43 and reattaching the detached one of the first and second connectors 41, 43 to its respective bracket 42, 44. [0035] The embodiment may be designed to service support structures 30 with a diameter in the range 8-22 inches (0.20-0.56 m). Alternative embodiments of different sizes and/or numbers of frame sections la, lb may be provided to service support structures of other diameters.

[0036] Driveable functions of the apparatus in embodiments of the invention, such as the embodiments as described above, include: i. Move up/down, by driving the driveable wheel(s) 8, 9 in contact with the surface of the support structure 30 in forward/re verse directions respectively; ii. Move tool carriage 15 clockwise/anticlockwise along the guide rail 14; iii. Tool adjustment forward/backward, by driving the tool 22 radially forward/backward respectively, with respect to the carriage 15; iv. Adjusting the latching mechanism 40.

[0037] The driveable functions may be each be powered and/or controlled by hydraulic or electric power, for example by hydraulic hoses and/or electrical cables connected to the apparatus. In one preferred embodiment, the apparatus includes a battery that supplies power to the drive wheels, the tools and/or the tool carriage.

[0038] The apparatus is preferably controlled by a remote control unit which allows control of some or all of the functions described above, preferably by means of corresponding user actuable controls. The remote control unit may be connected by a wired or wireless connection to a controller of the functions described above. Power for driving the functions may be provided by a power supply, under the control of the controller.

[0039] Preferably, the drive speeds of the wheels 8, 9 and of the tool carriage 15 are controllable independently to adjust for the servicing required. Alternatively or additionally, the remote control unit or controller may be programmable or programmed to carry out a particular service by coordinated control of the different functions, optionally in response to the distance travelled as detected by the distance sensor(s), and/or the circumferential position of the tool carriage 15 as detected by the circumferential position sensor(s). This may enable a predetermined section of the support structure 30 to be serviced.

[0040] The number of wheels 8, 9 that are driven or drivable may be varied according to the load to be carried by the apparatus or the operating conditions of the apparatus.

[0041] Preferably, the frame sections la, lb are constructed of lightweight material such as Delrin (RTM). For example, the mass of the apparatus may be in the range 30-50 kg.

[0042] The above embodiments are designed for servicing a circular cylindrical support structure 30 such as a pile, and therefore the frame 1 is approximately circular cylindrical, having an inner diameter slightly larger than the diameter of the support structure 30. Alternative embodiments may have alternative shapes and sizes to match the type of support structure 30 which they are designed to service. For example, a square or rectangular cylindrical frame 1 may be used in an embodiment designed for servicing a square or rectangular cylindrical support structure 30.

[0043] The above embodiments may be used in a marine or aquatic splash zone, or at a shallow depth below the surface, such as 10 metres. The embodiments may be modified for operation below 10 metres in depth, for example by the use of suitable hydraulic seals. The embodiments may be used for servicing pipes, to the extent that they are not impeded by the support of the pipes.

[0044] Alternative embodiments of the present invention may be used for servicing nonmarine or on-shore support structures, such as wind turbines or radio masts. For these applications, the frame sections la, lb may be provided with one or more detachable or permanently attached wheels for or other transport members, allowing the frame segments to be moved into position around the support structure, along the ground.

[0045] Alternative embodiments of the invention, which may be apparent to the skilled person on reading the above description, may fall within the scope of the invention as defined by the accompanying claims. List of parts and reference numerals