Lifting and / or lowering apparatus and support apparatus for such lifting and / or lowering apparatus

Abstract

A secondary steel installation tool (SSIT) 2 is disclosed. A lifting and / or lowering apparatus (12) comprises a base structure (8) adapted to be supported by a monopile (4), an external lifting ring (14) for engaging an external surface of the base structure (8) and / or monopile (4) and providing access to said external surface, and an internal lifting ring (20) for engaging an internal surface of the base structure (8) and / or monopile (4) and providing access to said internal surface. Lifting winches (24) selectively lift and / or lower the external or internal lifting ring relative to the monopile (4), and one or more pins selectively fix the external or internal lifting ring in position relative to the base structure (8).

Description

[0001] The present disclosure relates to a support apparatus for supporting a lifting and / or lowering apparatus on a hollow support, and relates particularly, but not exclusively, to a support apparatus for supporting lifting and / or lowering apparatus on monopiles for offshore wind turbine generators.

[0002] Monopiles are tubular steel structures that are driven into the seabed to provide secure foundations for offshore wind turbine generators. Historically, monopiles could not be positioned in the seabed very accurately, particularly with regard to verticality. Wind turbine generators are mounted on top of tower sections which can protrude vertically a significant height - well over 100m in some cases. This means that any error in verticality will result in significant positional offset at the top of the tower which could potentially create loading scenarios outside of the design parameters for the wind turbine.

[0003] Transition pieces are tubular steel structures which are installed between the monopile and the turbine tower. The primary function of the transition piece is to allow for the correction of monopile positional errors that occur during installation into the seabed. Transition pieces have an internal diameter at their bottom end greater than the outside diameter at the monopile top end. Once the monopile has been installed in the seabed, the transition piece is lifted over the top of the monopile and then lowered around the monopile until the monopile protrudes inside of the transition piece the required distance. The transition piece is then surveyed to ensure it is within the required positional tolerances. The transition piece is fixed to the monopile by pumping grout into the recess between the transition piece internal diameter and the monopile outside diameter. The turbine tower is then installed onto the transition piece, typically via a bolted flange connection.

[0004] Methods of installing monopiles have improved such that they can now be installed with far better positional accuracy - to the point that transition pieces are not required in some cases. Monopiles have been developed with flange connections that protrude above sea-level and allow the turbine towers to be bolted directly to the monopile. This method is generally referred to as 'TP-less' turbine installation.

[0005] A secondary function of the transition piece is to provide mounting positions for various access components and equipment. The access components and equipment are collectively referred to as 'secondary steel'. For installations using transition pieces the secondary steel is integrated into the transition piece structure. For TP-less installations the secondary steel must be lifted and mounted on the monopile once it has been driven into the seabed. The secondary steel is typically transported to the wind farm on a vessel with a heavy lift crane and multiple sets of secondary steel are stored on deck.

[0006] Generally, it is not practical to lift secondary steel onto the monopile directly with the crane. Lifting of each of the secondary steel components has its own challenges, some of the main challenges being: Heavy lift vessel cranes are not able to position their hooks accurately enough to locate the secondary steel onto / into their respective mounts. Accurate positioning can also be complicated by wind and wave loading. Tag lines can sometimes be used to help with positioning. However, the position of the vessel relative to monopile cannot be guaranteed and sometimes the monopile will obstruct the use of tag lines.

[0007] Some of the components, for example the boat landing, have multiple points that must be engaged simultaneously. This is very difficult to achieve with a single lift line. Causing any damage to the monopile flange, outside surface or secondary steel during lifting is not acceptable. Any damage caused, including damage to paintwork, will need to be repaired. Offshore repairs of this type are very expensive and so any risk of causing damage must be minimised.

[0008] To mitigate these issues, specialist lifting tools have been developed, sometimes referred to as Secondary Steel Installation Tools (SSIT). SSITs are used to lift the secondary steel components from their storage positions on deck. SSITs commonly have integrated lifting or handling mechanisms such as winches or manipulator arms to lift and position secondary steel components more accurately. The SSITs will also typically have guidance and location features that allow them to be engaged with the top flange of the monopile. Once engaged with the monopile, the SSIT is no longer subject to movements due to environmental loading that it would when hanging from a crane. This allows the more accurate, integrated lifting and handling mechanisms to carry out the last stage of the installation from a stable base. Some tools can lift more than one secondary steel component simultaneously from the vessel. This is advantageous as each lift to and from the monopile is time consuming. Engaging with the monopile is operationally risky, so minimising the number of times this must be done is also advantageous. However, lifting of multiple secondary steel components is technically challenging as each component has a different shape, centre of gravity, mass, and mounting features. This can therefore add significant complexity to the SSIT and therefore capital cost, which must then be balanced against any operational savings. It is believed that there are currently no SSITs in existence that are capable of lifting all of the secondary steel components with a single tool, i.e. multiple lift tools are required for the installation of the secondary steel on each monopile. The use of multiple tools has some significant disadvantages as follows: Changing of lifting tools is time consuming - over multiple monopile installations this time inefficiency can add significant cost to a project. The lifting tools can take up a large amount of deck space - deck space that could be used to transport additional secondary steel components.

[0009] Embodiments of the disclosure seek to overcome one or more of the above disadvantages.

[0010] According to an aspect of the disclosure, there is provided a support apparatus for supporting a lifting and / or lowering apparatus on a hollow support, the support apparatus comprising: a body part adapted to be supported by the hollow support; and a plurality of restraining members for resisting lateral movement of the body part relative to the hollow support when the body part is supported on the hollow support; wherein a plurality of said restraining members are mounted to the body part and are adapted to selectively engage an inner surface or an outer surface of the hollow support to resist said lateral movement of the body part. By providing restraining members adapted to selectively engage an inner surface or an outer surface of the hollow support to resist lateral movement of the body part, this provides the advantage of enabling the same restraining members to engage either the outer surface of the support, leaving the inner surface unobstructed for objects being mounted to the inner surface, or the inner surface of the support, leaving the outer surface unobstructed for objects being mounted to the outer surface.

[0011] At least one said restraining member may be pivotable between at least one first position and at least one second position to selectively engage said inner surface or said outer surface.

[0012] This provides the advantage of allowing for the same restraining member to be moved from the inner or outer surface of the hollow support, without the need to remove and reattach the restraining member.

[0013] The apparatus may further comprise locking means for locking at least one said restraining member in position relative to the body part.

[0014] This provides the advantage of further improving the stability of the apparatus.

[0015] At least one said restraining member may be adapted to define a respective first engaging surface inclined relative to a respective internal and / or external surface of the hollow support to assist in mounting of the support apparatus to the hollow support, and a respective second engaging surface for resisting said lateral movement of the body part when supported by the hollow support.

[0016] This provides the advantage of assisting in mounting the apparatus to the hollow support.

[0017] According to another aspect of the disclosure, there is provided a lifting and / or lowering assembly comprising: a lifting and / or lowering apparatus; and a support apparatus as defined above for supporting the lifting and / or lowering apparatus on a hollow support.

[0018] The assembly may comprise a first support member for engaging an external surface of the body part and / or hollow support and providing access to said external surface.

[0019] This provides the advantage of restraining movement of the object relative to the hollow support, thereby reducing the risk of damage to the hollow support.

[0020] The first support member may be adapted to support at least one object during lifting and / or lowering of said object relative to the hollow support.

[0021] The assembly may further comprise first indexing means for causing rotational movement of said first support member relative to the hollow support about a longitudinal axis of the hollow support.

[0022] This provides the advantage of enabling more accurate location of an object relative to the hollow support.

[0023] At least one said first support member may further comprise a plurality of first rollers for engaging said external surface and allowing movement of said first support member relative to the hollow support in a direction substantially parallel to said longitudinal axis of the hollow support.

[0024] The lifting and / or lowering apparatus may comprise a second support member for engaging an internal surface of the body part and / or hollow support and providing access to said internal surface.

[0025] The second support member may be adapted to support at least one object during lifting and / or lowering of said object relative to the hollow support.

[0026] The assembly may further comprise second indexing means for causing rotational movement of said second member relative to the hollow support about a longitudinal axis of the hollow support.

[0027] Said second support member may further comprise a plurality of second rollers for engaging said internal surface and allowing movement of said second support member relative to the hollow support in a direction substantially parallel to said longitudinal axis of the hollow support.

[0028] The assembly may further comprise winch means for selectively lifting and / or lowering said first support member or said second support member.

[0029] By providing winch means for selectively lifting and / or lowering the first support member or the second support member, this provides the advantage of enabling the lifting / lowering of the first and second support members to be carried out by means of a single winch device. This in turn enables more compact assembly and reduced weight of the apparatus.

[0030] The assembly may further comprise fixing means for selectively fixing said first support member or said second support member in position relative to said body part.

[0031] This provides the advantage of enabling a single winch means to lift and / or lower the first support member and / or the second support member, thereby enabling fewer components to be used, thereby reducing the weight of the apparatus. Embodiments of the disclosure will now be described, by way of example only and not in any limitative sense, with reference to the accompanying drawings, in which: Figure 1 is a perspective view of a secondary steel installation tool (SSIT) of an embodiment; Figure 2 is a perspective view of a top deck assembly and base structure of the SSIT of Figure 1; Figures 3A to 3C illustrate different positions of an external lifting ring of the SSIT of Figure 1; Figure 4 is a detailed view of the external lifting ring of Figures 3A to 3C; Figures 5A and 5B show different positions of an internal lifting ring of the SSIT of Figure 1; Figure 6 shows a winch arrangement for lifting and lowering the internal and external lifting rings of the SSIT of Figure 1; Figure 7 is a perspective view of guidance arms of the SSIT of Figure 1; Figures 8A and 8B show different positions of one of the guidance arms of Figure 7; Figures 9A and 9B show different positions of a boat landing during installation thereof by means of the SSIT of Figure 1; Figure 10 is a detailed view of part of the tool of Figure 1; Figure 11 is a partially cut away perspective view of part of the arrangement of Figure 10; Figure 12 is a schematic representation of the lifting and lowering apparatus of the arrangement of Figure 10; Figure 13 is a schematic representation of the arrangement of Figure 12 lowering an external lifting ring of the tool of Figure 1; Figure 14 is a schematic representation of the arrangement of Figure 12 lowering an internal lifting ring of the tool of Figure 1;. Figure 15 is a detailed view from one side and below of part of the tool of Figure 1; Figure 16 is a detailed view from one side and above of part of the tool of Figure 1; and Figure 17 is a partially cut away view of the arrangement of Figure 16.

[0032] Referring to the Figures, a lifting and / or lowering assembly in the form of a secondary steel installation tool (SSIT) 2 for mounting to a hollow support in the form of a monopile 4 for an offshore wind turbine generator has a support apparatus 6 comprising a body part in the form of a base structure 8 adapted to be supported by the monopile 4 and restraining members in the form of guidance arms 10 for resisting lateral movement of the base structure 8 relative to the monopile 4. The SSIT 2 includes a lifting and / or lowering apparatus 12 having a first support member in the form of an external lifting ring 14 for engaging an external surface 16 of the base structure 8 and / or the monopile 4 and supporting at least one object such as a boat landing 18 for lifting and / or lowering of the boat landing 18 relative to the monopile 4, and a second support member in the form of an internal lifting ring 20 for engaging an internal surface 22 of the base structure 8 and / or the monopile 4 and supporting at least one object (not shown) during lifting and / or lowering of the object relative to the monopile 4. The assembly further includes winch means in the form of a plurality of lifting winches 24 for a selectively lifting and / or lowering the external lifting ring 14 or internal lifting ring 20, the winches 24 being mounted to a top deck assembly 26, the top deck assembly 26 being rotatably mounted to the base structure 8 by means of a roller ring 21 for receiving driven rollers 23 mounted to the top deck assembly 26.

[0033] The external lifting ring 14 is provided with a plurality of first rollers in the form of radially moveable rollers 28 for engaging the external surface 16 of the base structure 8 and / or the monopile 4 and allowing movement of the external lifting ring 14 in a generally vertical direction relative to the monopile 4, and first indexing means having second rollers in the form of a plurality of circumferential driven rollers 30 for engaging the external surface 16 of the base structure 8 and / or the monopile 4 and allowing rotational movement of the external lifting ring 14 about a longitudinal axis (not shown) of the monopile 4. The internal lifting ring 20 is provided with third rollers in the form of a plurality of radial rollers 32 for engaging the internal surface 22 of the base structure 8 and / or the monopile 4 and allowing movement of the internal lifting ring 20 in a generally vertical direction relative to the monopile 4. The internal lifting ring 20 is also provided with second indexing means in the form of circumferential driven rollers 25 for engaging the internal surface 22 to enable rotational movement of the internal lifting ring 20 about the longitudinal axis of the monopile 4. The rotation of the top deck assembly 26 relative to the monopile 4 can be controlled to match the rotation of the inner 20 and outer 14 lifting rings to maintain cables 27 extending between the top deck assembly and the inner 20 or outer 14 lifting ring being lifted and / or lowered vertical. Each of the rollers 25, 30 is mounted on an actuator 29 which pushes the respective roller 25, 30 against the respective surface 16, 22 of the base structure 8 and / or the monopile 4 to provide sufficient traction to rotate the respective ring 14, 20 relative to the monopile 4.

[0034] Each of the guidance arms 10 is pivotable about a respective pivot 34 between a first position (Figure 8A) in which the guidance arm 10 engages the internal surface 22 of the monopile 4 and a second position (Figure 8B) in which the guidance arm 10 engages the external surface 16 of the monopile 4. Each of the guidance arms 10 defines a respective first engaging surface in the form of a lead-in surface 36 inclined relative to the internal 22 or external 16 surface of the monopile 4 to be engaged, to assist in locating the SSIT 2 on the monopile 4. Each of the guidance arms 10 also defines a respective second engaging surface in the form of a shear stop 38 for resisting lateral movement of the SSIT 2 when supported by the monopile 4. Each of the guidance arms 10 is lockable in position relative to the monopile 4 by means of locking means in the form of a pin 40.

[0035] Referring to Figures 6 and 10 to 14, the external 14 and internal 20 lifting rings are selectively actuated by means of the plurality of winches 24 to lift and / or lower the external 14 and internal 20 lifting rings into the desired position. This is achieved by selectively fixing the external 14 or internal 20 lifting ring in position relative to the top deck assembly 26 by means of fixing means in the form of a first part comprising a pin (not shown) insertable into an aperture 42 (Figure 6) in the external lifting ring 14 or a second part comprising a pin 31 (Figure 11) insertable into an aperture 43 (Figure 17) in the internal lifting ring 20. The pins are operated by means of suitable actuators (not shown). Each of the winches 24 can pay in or pay out a respective cable 27, which passes over a respective turnaround sheave 33 on the top deck assembly 26 and is diverted to a respective outer ring lift sheave 35 on the external lifting ring 14. The cable 27 is then diverted back to the top deck assembly 26 and passes over a respective further turnaround sheave 37 and is then diverted to a respective lift sheave 39 on the internal lifting ring 20. The cable is then diverted back to the top deck assembly 26 and is fixed to the top deck assembly 26 at a termination point (not shown).

[0036] It will be appreciated by persons skilled in the art that the above embodiment has been described by was of example only and not in any limitative sense, and that various alterations and modifications are possible without departure from the scope of the disclosure as defined by the appended claims.

Claims

1. A support apparatus for supporting a lifting and / or lowering apparatus on a hollow support, the support apparatus comprising: a body part adapted to be supported by the hollow support; and a plurality of restraining members for resisting lateral movement of the body part relative to the hollow support when the body part is supported on the hollow support; wherein a plurality of said restraining members are mounted to the body part and are adapted to selectively engage an inner surface or an outer surface of the hollow support to resist said lateral movement of the body part.

2. An apparatus according to claim 1, wherein at least one said restraining member is pivotable between at least one first position and at least one second position to selectively engage said inner surface or said outer surface.

3. An apparatus according to any one of the preceding claims, further comprising locking means for locking at least one said restraining member in position relative to the body part.

4. An apparatus according to any of the preceding claims, wherein at least one said restraining member is adapted to define a respective first engaging surface inclined relative to a respective internal and / or external surface of the hollow support to assist in mounting of the support apparatus to the hollow support, and a respective second engaging surface for resisting said lateral movement of the body part when supported by the hollow support.

5. A lifting and / or lowering assembly comprising: a lifting and / or lowering apparatus; a support apparatus according to anyone of the preceding claims for supporting the lifting and / or lowering apparatus on a hollow support.

6. An assembly according to claim 5, wherein the lifting and / or lowering apparatus comprises a first support member for engaging an external surface of the body part and / or hollow support and providing access to said external surface.

7. An assembly according to claim 6, wherein the first support member is adapted to support at least one object during lifting and / or lowering of said object relative to the hollow support.

8. An assembly according to claim 6 or 7, further comprising first indexing means for causing rotational movement of said first support member relative to the hollow support about a longitudinal axis of the hollow support.

9. An assembly according to any one of claims 5 to 8, wherein said first support member further comprises a plurality of first rollers for engaging said external surface and allowing movement of said first support member relative to the hollow support in a direction substantially parallel to said longitudinal axis of the hollow support.

10. An assembly according to any one of claims 5 to 9, wherein the lifting and / or lowering apparatus comprises a second support member for engaging an internal surface of the body part and / or hollow support and providing access to said internal surface.

11. An assembly according to claim 10, wherein the second support member is adapted to support at least one object during lifting and / or lowering of said object relative to the hollow support.

12. An assembly according to claim 10 or 11, further comprising second indexing means for causing rotational movement of said second member relative to the hollow support about a longitudinal axis of the hollow support.

13. An assembly according to any one of claims 10 to 12, wherein at least one said second support member further comprises a plurality of second rollers for engaging said internal surface and allowing movement of said second support member relative to the hollow support in a direction substantially parallel to said longitudinal axis of the hollow support.

14. An assembly according to any one of claims 10 to 13, further comprising winch means for selectively lifting and / or lowering said first support member or said second support member.

15. An assembly according to any one of claims 10 to 14, further comprising fixing means for selectively fixing said first support member or said second support member in position relative to said body part.

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