Device and method of lifting a tubular pile

Abstract

The present invention relates to a lifting device for lifting a tubular pile comprising a lifting member including a centerline, a plurality of docking elements that are movably mounted on the lifting member at angular distances from each other around the centerline, and actuators for moving the respective docking elements relative to the lifting member. The docking elements are movable in the longitudinal direction of the centerline along respective guides of the lifting member. The guides are inclined relative to the centerline in such a way that the docking elements move in the radial direction of the centerline when moved in the longitudinal direction of the centerline.The actuators are functionally interconnected in such a way that, under operating conditions, the actuators move the docking elements simultaneously until the first actuator reaches a counterforce that is higher than the counterforce of the second actuator, after which the second actuator is moved further.

Description

1 / 6 DESCRIPTIVE REPORT “DEVICE AND METHOD FOR LIFTING A TUBULAR STACK”

[001] The present invention relates to a lifting device for lifting a tubular pile, comprising a lifting member including a centerline, a plurality of docking elements that are movably mounted on the lifting member at angular distances from each other around the centerline and actuators for moving the respective docking elements relative to the lifting member, wherein the docking elements are movable in the longitudinal direction of the centerline along respective guides of the lifting member, these guides being inclined relative to the centerline in such a way that the docking elements move in the radial direction of the centerline when they are moved in the longitudinal direction of the centerline.

[002] A lifting device like this is known from WO 2014 / 084738. Under operating conditions, the lifting device is inserted into an upper end of a tubular pile, after which the fitting elements are moved outwards towards an inner wall of the tubular pile in such a way that they grip the pile. This allows the lifting device to lift the tubular pile. The known lifting device is suitable for gripping a pile that has an integral or nearly integral circular cross-section. If a pile has an oval or slightly oval cross-section, or if the stiffness of the pile in different radial directions varies, one or more of the fitting elements may have insufficient grip to engage an inner wall of the pile when the lifting device is inserted into an upper end of the pile.

[003] The present invention aims to provide a lifting device that has a reliable gripping function.

[004] For this purpose, the actuators are functionally interconnected in such a way that, under operating conditions, the actuators move the docking elements simultaneously until a first actuator reaches a counterforce that is higher than a counterforce of a second actuator, after which, Petition 870210108411, dated 11 / 23 / 2021, pp. 46 / 61 2 / 6 the second of the actuators is moved additionally.

[005] One advantage of the invention is that all the fitting elements will fit properly into a stack before a lifting operation is initiated. The functional interconnection of the actuators creates an automatic gripping control.

[006] In a practical embodiment, the actuators comprise hydraulic cylinders including their respective pressure chambers, which communicate with each other. When a hydraulic pump provides oil pressure to all the hydraulic cylinders, the fitting elements will be moved simultaneously. As soon as one of the fitting elements contacts an inner wall of a tubular stack, the corresponding hydraulic cylinder can encounter an increased counterforce. If another of the fitting elements can still move freely in the direction of the inner wall, the corresponding hydraulic cylinder will be moved further, since the oil will automatically flow into the pressure chamber, which provides a lower backpressure.

[007] Each of the fitting elements may have a wedge shape which includes an outer side that is directed away from the lifting member and extends substantially parallel to the centerline. This means that the outer side may move parallel to the centerline.

[008] In one particular embodiment, a flange is mounted on the lifting member to contact an upper end of a monopile when at least part of the lifting device including the fitting elements is inserted into the monopile. This ensures a well-defined position of the lifting device on the monopile to be lifted.

[009] Each of the connecting elements may be provided with a resilient cover on one side of the connecting element that faces away from the lifting member. Such a cover may be made of rubber or similar materials. The resilient cover provides proper fitting performance between the connecting elements and the inner wall of the tubular pile. In addition, resilient covers are easy to repair in case of wear and / or breakage. It is noted that the remainder of Petition 870210108411, dated 11 / 23 / 2021, pp. 47 / 61 The 3 / 6 fitting element can be made of steel.

[010] The invention also relates to a method of lifting a tubular pile by means of a lifting device which is provided with a lifting member including a centerline and a plurality of docking elements which are movably mounted on the lifting member at angular distances from each other around the centerline, wherein the docking elements are movable in the longitudinal direction of the centerline along respective guides of the lifting member, these guides being inclined relative to the centerline in such a way that the docking elements move in the radial direction of the centerline when they are moved in the longitudinal direction of the centerline, wherein the method comprises the steps of inserting the lifting device into the tubular pile, moving the docking elements simultaneously in a direction in which they also move towards an inner wall of the tubular pile,To stop the movement of the first of the docking elements when it generates a counterforce that is higher than the counterforce of a second of the docking elements, while the second of the docking elements is moved additionally.

[011] The second of the docking elements can be interrupted when its counterforce reaches a predetermined level. This can be a pre-set maximum permissible level.

[012] The invention will be elucidated below in relation to schematic drawings which show an embodiment of the invention by way of example.

[013] Figure 1 is a perspective view of an embodiment of a lifting device according to the invention.

[014] Figure 2 is a view similar to Figure 1, but showing the lifting device in a different condition.

[015] Figure 3 is a base view of the embodiment shown in Figure 1.

[016] Figure 4 is a view similar to Figure 3, but showing the condition of the lifting device, as illustrated in Figure 2.

[017] Figure 5 is a cross-sectional view of the embodiment shown in Petition 870210108411, dated 11 / 23 / 2021, pp. 48 / 61 4 / 6 figure 1.

[018] Figure 6 is a view similar to Figure 5, but showing the condition of the lifting device, as illustrated in Figures 2 and 4.

[019] Figures 1 and 2 show an embodiment of a lifting device 1 according to the invention under two different conditions. Figures 3 and 4 show the base side of the lifting device 1 in the respective conditions. Figures 5 and 6 provide an internal view of the lifting device in order to illustrate its operation. The lifting device 1 is intended to be inserted into an upper end of a tubular stack or a monopile 2 in the condition shown in Figures 2, 4 and 6, and fixed to the monopile 2 in the condition shown in Figures 1, 3 and 5, after which the monopile 2 can be lifted. A monopile such as this 2 is, for example, located at the bottom of the sea and needs to be removed from there. For explanatory reasons, the monopile 2 is not shown in Figures 1, 2, 5 and 6.

[020] The lifting device 1 comprises a lifting member 3 which is provided with a lifting eye 4 that can be fitted by a crane hook (not shown). The lifting device 1 has eight wedge-shaped fitting elements 5 which are movably mounted on the lifting member 3 at an equiangular distance around a centerline CL of the lifting member 3. A different number of fitting elements 5 is conceivable. Each of the fitting elements 5 is movable in the longitudinal direction of the centerline CL along respective guides 6 of the lifting member 3. The guides 6 are inclined relative to the centerline CL. This forces the fitting elements 5 to move in the radial direction of the centerline CL when they are moved in the longitudinal direction of the centerline CL.The respective outer sides of the wedge-shaped docking elements 5 that are directed away from the lifting member 3 extend substantially parallel to the centerline CL. Therefore, the outer sides remain parallel to the centerline CL during the movement of the docking elements 5 relative to the lifting member 3.

[021] Figures 2, 4 and 6 show the condition of lifting device 1 in Petition 870210108411, dated 11 / 23 / 2021, pp. 49 / 61 5 / 6 that the fitting elements 5 are in their upper positions and figures 1, 3 and 5 show the condition of the lifting device 1 in which the fitting elements 5 are in their lower positions. In the latter condition, the fitting elements 5 are located at a greater distance from the central line CL than in the previous condition, and they fit into an inner wall of the monopile 2, as illustrated in figure 3.

[022] The fitting elements 5 can be moved relative to the lifting member 3 by actuators in the form of hydraulic cylinders 7 that are mounted on the lifting member 3 and the respective fitting elements 5. The hydraulic cylinders 7 have orientations inclined relative to the centerline CL of the lifting member 3 to operate along the respective lines that are parallel to the corresponding guides 6. Figure 6 shows the hydraulic cylinders 7 in the retracted condition and Figure 5 shows the hydraulic cylinders 7 in the extended condition. Each of the hydraulic cylinders 7 has a pressure chamber 8 inside which oil is pressurized when the hydraulic cylinder 7 needs to be extended. The pressure chambers 8 of all the hydraulic cylinders 7 communicate with each other, as illustrated by a simplified hydraulic circuit 9 in Figures 5 and 6.Consequently, by applying oil pressure to the hydraulic cylinders 7 to move the fitting elements 5 in the outward direction of the lifting member 3, the oil pressure in all pressure chambers 8 will be substantially equal. The oil chambers for retracting the hydraulic cylinders 7 also communicate with each other through a hydraulic circuit 11.

[023] The lifting device 1 is also provided with a flange 10 which has a fixed position relative to the lifting member 3. This allows the lifting device 1 to rest on the stack 2 when it is inserted into the stack 2.

[024] After the lifting device 1 is placed inside the stack 2, as shown in figure 4, all the fitting elements 5 will be moved substantially simultaneously until one first makes contact with the inner wall of the stack 2, which creates a higher counterforce on Petition 870210108411, dated 11 / 23 / 2021, pp. 50-61 6 / 6 corresponding hydraulic cylinder 7 than in the remaining fitting elements 5 which are still at a distance from the inner wall of the monopile 2. As a consequence, the remaining fitting elements 5 will be additionally actuated until a next one makes contact with the inner wall of the monopile 2, and so on. Therefore, in the case where the monopile 2 is not fully circular cylindrical, the locations of the fitting elements 5 in a direction along the central line CL in the extended conditions of the hydraulic cylinders 7 may be different.

[025] The invention is not limited to the embodiment shown in the drawings and described above, which may be varied in different ways within the scope of the claims and their technical equivalents. For example, the hydraulic cylinders may be replaced by alternative actuators that are functionally interconnected to achieve the same function of the lifting device as set forth. Petition 870210108411, dated 11 / 23 / 2021, pp. 51 / 61

Claims

1 / 2 CLAIMS 1. Lifting device (1) for lifting a tubular stack (2), characterized by comprising a lifting member (3) including a centerline (CL), a plurality of docking elements (5) that are movably mounted on the lifting member (3) at angular distances from each other around the centerline (CL) and actuators (7) for moving the respective docking elements (5) relative to the lifting member (3), wherein the docking elements (5) are movable in the longitudinal direction of the centerline (CL) along respective guides (6) of the lifting member (3), these guides (6) being inclined relative to the centerline (CL) in such a way that the docking elements (5) move in the radial direction of the centerline (CL) when moved in the longitudinal direction of the centerline (CL), wherein the actuators (7) are functionally interconnected in such a way that, under operating conditions,the actuators (7) move the docking elements (5) simultaneously until a first actuator (7) reaches a counterforce that is higher than a counterforce of a second actuator (7), after which the second actuator (7) is moved further.

2. Lifting device (1) according to claim 1, characterized in that the actuators comprise hydraulic cylinders (7) including respective pressure chambers (8), which communicate with each other.

3. Lifting device (1) according to claim 1 or 2, characterized in that each of the fitting elements (5) has a wedge shape including an outer side that is directed away from the lifting member (3) and that extends substantially parallel to the centerline (CL).

4. Lifting device (1) according to any of the preceding claims, characterized by a flange (10) being mounted on the lifting member (3) to contact an upper end of a monopile (2) when at least a part of the lifting device (1) including the fitting elements (5) is inserted into the monopile (2).

5. Lifting device (1) according to any of the previous claims, characterized in that each of the fitting elements (5) is provided with a resilient cover on one side of the fitting element (5) that faces away from the lifting member (3).

6. Method for lifting a tubular pile (2) by means of a lifting device (1) which is provided with a lifting member (3) including a centerline (CL), a plurality of docking elements (5) which are movably mounted on the lifting member (3) at angular distances from each other around the centerline (CL), wherein the docking elements (5) are movable in the longitudinal direction of the centerline (CL) along respective guides (6) of the lifting member (3), these guides (6) being inclined relative to the centerline (CL) in such a way that the docking elements (5) move in the radial direction of the centerline (CL) when they are moved in the longitudinal direction of the centerline (CL), characterized in that the method comprises the steps of inserting the lifting device (1) into the tubular pile (2), moving the docking elements (5) simultaneously in a direction in which they also move towards an inner wall of the tubular pile (2),to interrupt the movement of a first of the docking elements (5) when it generates a counterforce that is higher than a counterforce of a second of the docking elements (5), while the second of the docking elements (5) is moved additionally.

7. Method according to claim 6, characterized in that the second of the fitting elements (5) is interrupted when its counterforce reaches a predetermined level. Petition 870210108411, dated 11 / 23 / 2021, pp. 53 / 61

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