The invention relates to a temporary working platform, in particular a temporary working platform for removable attachment to a column of an offshore structure.

Temporary working platforms for marine applications are typically used to accommodate workers performing tasks such as maintenance activities to columns of offshore structures. Usually, temporary working platforms are mounted to the columns using mounting constructions that are permanently or semi -permanently provided in the exterior wall of the columns. Then, damage may be caused to the carrying structure of the columns reducing their operational lifetime.

An object of the invention therefore is to provide a temporary working platform that mitigates at least one of the above mentioned drawbacks.

Thereto, the invention provides a temporary working platform for removable attachment to a column of an offshore structure, comprising a frame for carrying a working structure, in particular a working surface, and a mounting mechanism for releasably mounting the working platform to said column, from a side of the column.

By providing a mounting mechanism for releasably mounting the working platform to said column, from a side of the column, the temporary working platform can be easily attached to columns of offshore structures, also to columns that are not provided with mounting elements. Due to the apphcation of a mounting mechanism such as a unit for disposing a non permanent adhesive, an electromagnetic device for magnetic coupling with a column having magnetizable material such as steel, and/or a clamping construction exploiting frictional forces between the column and the platform, there is no need to realize mechanical permanent or semi- permanent modification to the column structure for carrying the temporary working platform, thereby saving time, costs and reducing a chance that damage may occur at the columns, also after removal of the temporary working platform.

The clamping mechanism may support the frame and may be arranged for at least partially surrounding the column and for releasably clamping said column.

After installation of the platform, access to the platform can be provided either by a motion compensated access bridge such as a telescopic gangway or via rope access.

Preferably, the clamping mechanism includes a pair of clamping jaws having respective free ends, the jaws being mutually removable between a releasing state wherein the jaw free ends are relatively remote from each other and a clamping state wherein the jaw free ends are relatively close to each other, so as to efficiently provide a clamping principle to the temporary working platform, like a pair of pincers.

The pair of clamping jaws can be pivotably mounted to each other such that the clamping jaws are pivotable between the releasing state and the clamping state. However, in another structure the clamping jaws may move in another way, e.g. by shifting relative to each other.

Advantageously, an actuator can be provided for controllably driving the clamping mechanism.

The frame may include a pair of frame elements, each frame element being supported by a corresponding clamping jaw. However, multiple pairs of frame elements can be applied, or more generally, a set of individual frame elements. Further, a single frame element can be used, e.g. shdably resting on the clamping jaws.

Preferably, the clamping jaws and/or the frame elements are mainly shaped as curved portions for at least partially surrounding the column of an offshore structure, in order to match, at least partially the exterior curvature of the column.

An elastic layer can be mounted on a clamping side of the jaws, e.g. to further reduce a chance that any damage occurs to the column.

The clamping jaws and/or the frame elements may be located at mutually opposite locations, thereby providing a balance clamping force to the column.

Advantageously, the working structure may include a grating or another working surface, and/or a working device such as a hoist.

Preferably, a first coupling element is provided for releasable coupling to a second coupling element mounted on a transport system transporting the platform to and from the column of the offshore structure. Then, the platform can be deployed and retrieved easily using a motion compensated access bridge such as a gangway, without the use rope structures or hoisting units.

The first or second coupling element may include a guiding structure for guiding the first and second coupling elements towards each other and/or for providing a secure connection between the transport system and the temporary working platform.

The invention also relates to a transport system, such as a telescopic gangway, coupled to a temporary working platform, wherein, preferably, the second coupling element is mounted to a free end of the transport system.

Further, the invention relates to a vessel, comprising a transport system, such as a telescopic gangway.

The invention further relates to a telescopic gangway and a temporary working platform, wherein the telescopic gangway comprises first and second gangway parts which are telescopable relative to each other in a longitudinal direction, as well as a primary coupling element for removably coupling the telescopic gangway to the temporary working platform, and wherein the temporary working platform comprises a secondary coupling element for removably coupling the temporary working platform to the telescopic gangway, as well as an actuated clamping mechanism suitable for removably attaching the working platform to a column of an offshore construction by at least partially surrounding said column with said actuated clamping mechanism.

Also, the invention relates to a method of handling a temporary working platform.

The invention will be further elucidated on the basis of exemplary embodiments which are represented in the drawings. The exemplary embodiments are given by way of non-limitative illustration of the invention. In the drawings:

Fig. 1 shows a schematic perspective view of a temporary working platform according to the invention;

Fig. 2 shows a schematic top view of the temporary working platform shown in Fig. 1;

Fig. 3 shows a schematic side view of the temporary working platform shown in Fig. 1;

Fig. 4 shows a schematic front view of the temporary working platform shown in Fig. 1;

Fig. 5 shows a vessel comprising a telescopic gangway coupled to a temporary working platform according to the invention,

Fig. 6 shows the vessel depicted in Fig. 5, wherein the temporary working platform is attached to a column of an offshore construction,

Fig. 7 shows the vessel depicted in Fig. 5, wherein the temporary working platform has been decoupled,

Fig. 8 shows the vessel depicted in Fig. 5, wherein the telescopic gangway is coupling to the temporary working platform, Fig. 9 shows the vessel depicted in Fig. 5, wherein the temporary working platform has been released from the column of an offshore construction,

Fig. 10 shows a flow diagram of a method according to the invention,

Fig. 11A shows a schematic top view of another temporary working platform according to the invention, in a first state,

Fig. 11B shows a schematic top view of the temporary working platform of Fig. llAin a second state,

Fig. 12A shows a schematic side view of the temporary working platform of Fig. llAin the first state,

Fig. 12B shows a schematic side view of the temporary working platform of Fig. llAin the second state,

Fig. 13A shows a schematic top view of yet another temporary working platform according to the invention, in a first state, and

Fig. 13B shows a schematic top view of the temporary working platform of Fig. 13B in a second state.

In the figures identical or corresponding parts are represented with the same reference numerals. The drawings are only schematic representations of embodiments of the invention, which are given by manner of non-limited examples.

Figure 1 shows a schematic perspective view of a temporary working platform 1 according to the invention. The temporary working platform 1 includes a frame 2 and a mounting mechanism for releasably mounting the working platform to a column 20 of an offshore structure, from a side of the column 20. The mounting mechanism is provided, in the shown embodiment, with a clamping mechanism 3 supporting the frame. In use, the temporary working platform 1 can be removably attached to said column 20, using the clamping mechanism 3. The offshore structure is e.g. a drilling rig, drilling platform or offshore windmill, the column also referred to as jacket leg.

The frame 2 of the temporary working platform 1 is arranged for carrying a working structure such as a working surface 4 or another working structure such as a hoisting device. The working surface 4 may be implemented as a grating or another working surface such as a supporting plate.

The clamping mechanism 3 is arranged for at least partially surrounding a column 20 of an offshore structure and for releasably clamping said column 20.

In the shown embodiment, the clamping mechanism 3 includes a pair of clamping jaws 3a, b that are pivotably mounted to each other such that the clamping jaws 3a, b are pivotable with respect to a pivoting axis PA between a releasing state and a clamping state. Each of the clamping jaws 3a, b has a free end 5a, b, respectively, also referred to as distal free ends 5a, b. In the releasing state, the jaw free ends 5a, b are relatively remote from each other, while, in the clamping state, the jaw free ends 5a, b are relatively close to each other. Further, the clamping mechanism 3 may include a locking element for locking the jaw free ends 5a, b to each other, in the clamping state so as to counteract that the clamping jaws 3a, b move unintentionally away from each other. In the releasing state, the platform 1 can be moved towards or from the column 20 of the offshore structure. In the clamping state, the platform 1 is releasably attached to said column 20.

The temporary working platform 1 further includes an actuator 6 for controllably driving the clamping mechanism 2. The actuator 6 may include a motor 6” such as a hydraulic or an electric motor, as well as a driving element 6’ driven by said motor 6” for moving a first clamping jaw 3a relative to a second clamping jaw 3b such that the clamping mechanism opens from or closes towards the clamping state, like a pair of pincers. The actuator 6 may be operated by a control unit having an interface for manual or remote interaction by a user of the actuator 6.

Figure 2 shows a schematic top view of the temporary working platform 1 shown in Fig. 1. Here, the clamping mechanism 3 is shown in both the clamping state CS and the releasing state RS.

In the shown embodiment, the driving element 6’ pivots the first clamping jaw 3a relative to the second clamping jaw 3b by exerting a driving force to the first clamping jaw 3a. Here, the first clamping jaw 3a is formed as a lever rotating around the pivoting axis PA having a proximal end 3a’ to which the driving element 6’ is connected for receiving said driving force. During movement, one of the jaw free distal ends 5a, b or both jaw free distal ends 5a, b move along a displacement path DPa, DPb that is mainly circular. In the shown embodiment, the jaw free distal ends 5a, b move in a symmetric way relative to a plane of symmetry PS, e.g. for balancing reasons.

Generally, the actuator may be provided in or on the platform 1 or on another structure such as a telescopic gangway or another transport system coupled to the temporary working platform 1.

Further, the clamping mechanism 3 may be implemented as another structure wherein the clamping jaws 3a, b controllably move towards and from each other, e.g. following a non-circular curved or straight path, contrary to the circular displacement path DPa, DPb. Also, the clamping mechanism may include more than two clamping jaws or clamping elements for releasably clamping a column 20 of an offshore construction.

The frame 2 includes a pair of frame elements 2a, b wherein each frame element 2a, b is supported by a corresponding clamping jaw 2a, b.

Then, a wide angle range access to the column 20 is provided, e.g. at least 180 degrees or more. Further, a number of workers may work on the platform, up to a safety load of e.g. 500 kg. In another embodiment, the frame 2 includes more than two frame elements, e.g. four or six frame elements. Further, the frame 2 may include a single frame element, e.g. supported by one of the clamping jaws 3a, b.

In the shown embodiment, the clamping jaws 3 and the frame elements 2 are mainly shaped as curved portions for at least partially surrounding the column 20 of an offshore structure. Preferably, the clamping jaws and/or the frame element 2 are mainly shaped as annular portion segments around a common axis of symmetry AS mainly coinciding with a longitudinal axis of the column 20, in the clamped state of the platform 1. A radial inner contour 7 of the clamping jaws 3 and/or the frame elements 2 may have a constant curvature of radiation that may mainly match with the curvature of the exterior wall of the column 20.

The clamping jaws 3 may be provided with an elastic layer mounted on a clamping side of said jaws, such as the above mentioned radial inner contour 7, thereby reducing a chance that permanent damage may occur at the column 20 to be clamped. Further, the clamping jaws 3 may be provided with clamping shoes, at the radial inner contour 7.

The frame elements 2 and/or the clamping jaws are located at mutually opposite locations, symmetric with respect to the plane of symmetry, facing each other and clamping the column 20 between the opposite clamping jaws 3, as a pair of pincers.

Figure 3 shows a schematic side view of the temporary working platform 1 shown in Fig. 1.

Figure 4 shows a schematic front view of the temporary working platform 1 shown in Fig. 1.

The shown temporary working platform 1 is coupled to a telescopic gangway 72 described in more detail below. In the shown embodiment, the temporary working platform 1 has a first coupling element 8, e.g. mounted on the frame 2 or clamping mechanism 3, the first coupling element 8 being coupled to a second coupling element 9 mounted on the free end or tip 73 of the telescopic gangway 72. In the coupled state, the telescopic gangway 72 can transport the platform 1 to and from the column 20 of the offshore structure.

It is noted that the second coupling element 8, serving as a launch mechanism, may be mounted to a different gangway or to another transport system such as a crane.

Advantageously, the first coupling element 8 is provided with a guiding structure for guiding the first and second coupling elements 8, 9 towards each other. The guiding structure may include a self centering or self ahgning structure such as tapered or V-shaped guiding plates for aligning the second coupling element 9 in a horizontal and/or vertical direction, during a positioning / coupling process. Accordingly, the second coupling element 9 may include a corresponding wedge-shaped insertion element or tapered pin module to be guided and/or received by the guiding structure of the first coupling element 8. In a horizontal plane, the guiding structure may allow freedom for alignment and in a vertical plane for landing under different angles. Further, the guiding structure provides a secure locking position of the second coupling element. Alternatively, the second coupling element 9 may be provided with a guiding structure for guiding the first coupling element 8.

Further, the platform 1 includes a locking element 10 for locking the first coupling element 8 to the second coupling element 9.

Figure 5 shows a vessel 60 comprising a telescopic gangway 72 coupled to a temporary working platform 1 according to the invention.

Generally, a motion compensated gangway 70 comprises a movable transition deck 71 and a telescopic gangway 72 connected to the transition deck 71. The telescopic gangway 72 has a tip 73 that may be held, during operation of the motion compensated gangway 70, in close proximity of an object such as an offshore construction 21 to or from which a load or a person has to be transferred. The motion compensation system 70 may use actuators, e.g. hydraulic pistons 74, to compensate for relative motion between the vessel 60 on which the motion compensated gangway 70 is mounted and the object to or from which the load/person can be transferred. Said relative motion may for example result from waves or rolling, pitching, and/or yawing motion of a vessel or boat 60 floating on the water 61.

The telescopic gangway 72 may comprise a first and second gangway part, for example a telescoping and main boom, which are telescopable with respect to each other in a longitudinal direction to adjust a longitudinal length of the telescopic gangway. Within the context of this application the term telescopable is meant to be construed as being movable, such as being able to move in and out of each other and/or with respect to each other along said longitudinal direction.

The first and second gangway part may each have a walkboard or walkplank to facilitate transfer of persons and/or goods.

Motion compensated gangways per se, such as for compensating for vessel motions when transferring personnel and/or loads are known in the art. For example from the Ampelmann® system as disclosed in general in NL1027103, or systems disclosed in WO2012/138227 and W02013/10564.

Patent publication NL 1027103 discloses a vessel with a Stewart type construction for compensating motions of a ship. The construction comprises a transition deck, borne on six hydraulic cylinders, and motion sensors. During use, with the aid of the sensors, the motions of the vessel are measured. With the aid of these measurements, the orientation and/or position of the cyhnders is driven continuously so that the transition deck remains approximately stationary relative to the fixed world. A luffing gangway is connected to the transition deck. In this manner, motions of the vessel are compensated and for instance people or loads can be transferred from the vessel onto a stationary offshore construction, or vice versa.

In Fig. 5, the telescopic gangway 72 is coupled to the temporary working platform 1 using the coupling elements 8, 9 described above, for moving or deploying the platform to a column 20 of the offshore construction 21.

Figure 6 shows the vessel 60 depicted in Fig. 5, wherein the temporary working platform 1 is releasably attached to a column or pillar 20 of an offshore construction 21. Here, the clamping mechanism 3, also referred to as actuated clamping mechanism, has been actuated to move to the clamping state for clampingly attachment or clamp on to the column 21. Preferably, the telescopic gangway 72 pushes the platform 1 against the column 20 to temporarily fix a desired position of the platform 1 relative to the column 20 during closure of the clamping mechanism 3. Also, persons and/or goods can be transferred to the platform 1, e.g. for maintenance activities to the column 20.

Generally, the actuated clamping mechanism is suitable for removably attaching the working platform to a column of an offshore construction by at least partially surrounding said column with said actuated clamping mechanism.

Figure 7 shows the vessel 60 depicted in Fig. 5, wherein the temporary working platform 1 has been decoupled or disconnected. Here, the telescopic gangway 72 is moving away from the temporary working platform 1 attached to the column 20.

Figure 8 shows the vessel 60 depicted in Fig. 5, wherein the telescopic gangway 72 is landing for coupling to the temporary working platform 1, e.g. for potential people and/or goods transfer.

Figure 9 shows the vessel 60 depicted in Fig. 5, wherein the temporary working platform 1 has been released from the column 20 of an offshore construction 21. Here, the clamping mechanism 3 has been brought into the releasing state for retrieval of the platform 1 that can be re-used at another location of the column 20, to another column 20 or for further apphcations. Figure 10 shows a flow chart of a method of handling a temporary working platform according to the invention. Particularly, the method includes a step of handling 100 a temporary working platform 1 as described above.

The method may include a step of controllably driving the clamping mechanism 3 to a clamping state wherein the clamping mechanism 3 clamps a column 20 of an offshore construction 21.

The method may also include a step of decoupling the temporary working platform 1 from a transport system such as a telescopic gangway 72, after the step of controllably driving the clamping mechanism to the clamping state

Further, the method may include a step of coupling the temporary working platform 1 to a transport system such as a telescopic gangway 72, the temporary working platform 1 being removably attached to a column of an offshore construction. As a next step, the method may include a step of driving the clamping mechanism 3 to a releasing state wherein the clamping mechanism 3 releases the column 20 of the offshore construction 21.

Figure 11A shows a schematic top view of another temporary working platform 200 according to the invention, in a first state wherein the platform 20 is not mounted to the column 20 of the offshore structure.

Figure 11B shows a schematic top view of the temporary working platform 200 of Fig. 11A in a second state wherein the platform 20 is mounted to the column 20. Here, the clamping mechanism includes a multiple number of wedges 201, 202, 203, 204 oriented such that their tapered end 207 points upwardly. Further, the wedges 201-204 are located on a contour 208 for at least partly surrounding the column 20. Preferably, at least one wedge 201 of the multiple number of wedges 201-204 is movable along a moving direction M, between a first position PI, shown in Fig. 11A, enabling the column 20 to be received into said contour 208, and a second position P2, shown in Fig. 11B, wherein the column 20 is actually received into said contour 208.

The clamping mechanism further includes a locking ring, in the shown embodiment including two mainly semi-annular elements 205, 206 that are pivotable to each other between an open state for receiving the column 20, as shown in Fig. 11A and a closed state for locking the column 20, as shown in Fig. 11B.

Figure 12A shows a schematic side view of the temporary working platform 200 of Fig. 11A in the first state, corresponding with Fig. 11A.

During a process of mounting the temporary working platform 200 to the column 20, the at least one wedge 201 is brought in the first position PI, and the semi-annular elements 205, 206 are brought in the open state, as shown in Fig. 11A. Then, the column 20 is received into the contour 208 and in the semi-annular elements 205, 206. Subsequently, the at least one wedge 201 is brought into the second position P2, and the semi-annular elements 205, 206 are brought into the closed state, as shown in Fig. 11B, thereby locking the column 20 in a mainly horizontal plane.

As a next step, the semi-annular elements 205, 206 move downwardly along a mainly downward direction D, thereby pressing the wedges 201-204 radially inwardly towards the column 20 so as to clamp the platform 200 to the column 20, the locking ring blocking any movement of the wedges 201-204 in a radial, circumferential or downward direction D.

Figure 12B shows a schematic side view of the temporary working platform 200 of Fig. llAin the second state, corresponding to Fig. 11B, after moving the semi-annular elements 205, 206 downwardly.

The temporary working platform 200 can be removed from the column 20 by performing the above steps in a reverse order.

Various variations are possible. As an example, more or less than four wedges can be applied. Further, in addition or alternative to the wedges, pressure shoes can be applied pressurizable against the column from respective circumferential positions. Also, a clamping belt can be applied releasably enclosing the column, from a side of the column 20.

Figure 13A shows a schematic top view of yet another temporary working platform 200 according to the invention, in a first state. Further, Figure 13B shows a schematic top view of the temporary working platform 200 of Fig. 13B in a second state. Here, the clamping mechanism of the platform 200 includes two mainly semi-annular clamping elements 211, 212 that are mutually rotatable between the first state wherein they mainly overlap, and the second state wherein they do not overlap or only for minor portion. In the first state, the clamping elements 211, 212 may receive the column 20, while in the second state, said clamping elements 211, 212 lock the column 20 in a mainly horizontal plane. Any movement in a vertical direction may be blocked by an additional mechanism, such as pressurizing shoes described above. Further, a downward movement of the semi-annular clamping elements 211, 212 may be blocked, in the second state, if the column 20 has a conical shape, tapered upwardly.

The mounting mechanism of the temporary working platform may further include other mounting structures, optionally instead of a clamping mechanism, such as a unit for disposing a non-permanent adhesive between the column and the platform, and/or an electromagnetic device for magnetic coupling with a column having magnetizable material such as steel.

According to an aspect of the invention a telescopic gangway and a temporary working platform are provided, wherein the telescopic gangway comprises first and second gangway parts which are telescop able relative to each other in a longitudinal direction, as well as a primary coupling element for removably coupling the telescopic gangway to the temporary working platform, and wherein the temporary working platform comprises a secondary coupling element for removably coupling the temporary working platform to the telescopic gangway, as well as an actuated clamping mechanism suitable for removably attaching the working platform to a column of an offshore construction by at least partially surrounding said column with said actuated clamping mechanism. Here, the primary coupling element corresponds with the second coupling element described above arranged for removably coupling the telescopic gangway to the temporary working platform, while the secondary coupling element corresponds with the first coupling element described above for removably couphng the temporary working platform to the telescopic gangway.

It will be clear to the skilled person that the invention is not limited to the exemplary embodiment represented here. Many variations are possible.

Such variations shall be clear to the skilled person and are considered to fall within the scope of the invention as defined in the appended claims.

List of Reference Signs

AS Axis of symmetry

PA Pivoting Axis

PS Plane of symmetry cs Clamping State

RS Releasing State

DPa Displacement Path a

DPb Displacement Path b

1. Temporary Working Platform

2. Frame, frame elements

3. Clamping mechanism, clamping jaws

4. Working surface

5. Free end of clamping jaws

6. Actuator

7. Radial inner contour of clamping jaw

8. First coupling element

9. Second coupling element

10. Locking element

20. Column

21. Offshore construction

60. Vessel

61. Water

70. Motion compensated gangway

71. Movable Transition Deck

72. Telescopic gangway

73. Tip

74. Hydraulic piston

200. Temporary Working Platform

201-204. Wedge

205-206. Semi-annular element

207. Wedge tapered end

208. Contour

211-212. Semi-annular clamping element