Lifting device for picking up a member from the bottom of the sea

The invention relates to a lifting device for picking up a member from the bottom of the sea, the lifting device comprising;

BACKGROUND

The present invention relates to a lifting device for picking up a member from the bottom of the sea, the lifting device comprising a body, a housing and an engagement member coupled with the body and the housing such that the engagement member is moveably arranged to move in a radial direction with respect to the central axis. An example of this type of lifting device of the present invention is referred to as to internal lifting tool in the field.

Such a lifting device is known from GB1577778 which relates to lifting devices for tubular piles. GB1577778 provides a pipe lifting device having a plurality of latches movably mounted on the body and moveable between retracted positions and extended positions in which the latches project laterally of the body. The latches can be operated by a weight means and a drawing line.

Incorporating a free weight in the lifting device complicates the design and a drawing line is cumbersome in use during operations at the bottom of the sea.

Offshore lifting devices frequently put objects down on the seabed and pick these objects from the seabed later. Many times it is desirable that no connection between the lifting device and the vessel is maintained during the time that the object is down on the seabed. It is then required to make connection again with the object for lifting the object off the seabed. There are already different ways of doing this such as connect slings around trunnions, connect a shackle to the object or lower an internal lifting tool into a piece of pipe on the object. Such an Internal Lifting Tool (ILT) needs to be connected hydraulically to a powerpack to be activated. In most cases this is a powerpack on the vessel, but it can also be a subsea powerpack or a set of hydraulic accumulators. At all times this complicates the use of an ILT.

EP 0257943 relates to an apparatus for use in energy exploration and includes a support tubular member for connection to a drilling string, and a radially movable member to pass through tubular obstructions.

SUMMARY OF THE INVENTION

The invention aims to provide a lifting device which does not need an hydraulic connection when picking up an object from the seabed.

Another object of the invention is to improve a lifting device in that a problem associated therewith is at least partially solved.

Yet another object of the invention is to provide an alternative lifting device.

According to a first aspect of the invention this is realized with a lifting device for picking up a member from the bottom of the sea, the lifting device comprising;a body extending along a central axis of the lifting device and having means for connection to a hoist cable,a housing configured to be at least partially introduced into a cavity of the member to be picked up and accommodating at least a part of the body and wherein the body and the housing are moveable with respect to each other along the central axis of the lifting device,an engagement member, coupled with the body and the housing such that the engagement member is moveably arranged to move in a radial direction with respect to the central axis upon movement of the body and the housing with respect to each other, wherein the engagement member is moveable between a radially outward position wherein at least a part of the engagement member extends outside the housing for contacting the member to be picked up, and a radially inward position wherein the engagement member is substantially accommodated within the housing such that the lifting device can be introduced in a cavity of the member to be picked up, anda gas spring device coupled with the body and the housing for biasing the engagement member towards its radially outward position.

The body and the housing being moveable with respect to each other provides the possibility driving the engagement member with an external force, that is a force applied to the exterior of the housing. Thus, a direct force on the engagement member may drive the engagement member, which is the case during use of the lifting device, but the engagement member may also be driven indirectly by an external force through the housing and body.

Such an external force can be applied to the body and housing by the object to be picked up when the lifting device rests on the object to be picked up. In contrast known lifting devices drive engagement members directly by an internal force generated by an internal actuator, typically an hydraulic cylinder.

In an embodiment of the invention, the lifting device comprises cooperating guiding means for guiding the radial movement of the engagement member, and wherein the engagement member is coupled with the body and the housing and moveably arranged through said cooperating guiding means.

The cooperating guiding means constrain the movement of the engagement member with respect to the mutual movement of the housing and the body.

In an embodiment of the invention, the cooperating guiding means comprise cooperating bevelled faces to move the engagement member by wedging action upon movement of the body and the housing with respect to each other.

In an embodiment of the invention, the cooperating guiding means comprise a guide slot and a guide pin engaging the guide slot.

In an embodiment of the invention the guide slot is provided with the engagement member and the guide pin is provided with the housing.

In an embodiment of the invention, the cooperating guiding means comprise a guiding surface provided with the housing for guiding the engagement member when the engagement member moves between the radially outward position and the radially inward position.

In an embodiment of the invention, the engagement member is hingeably coupled with the body.

In an embodiment of the invention, the lifting device comprises a plurality of engagement members arranged around the central axis for distributing a lifting force FLover a circumference of the lifting device.

In an embodiment of the invention, the gas spring device comprises a cylinder system having a spring pressure chamber containing a compressible fluid, like compressed nitrogen for biasing the engagement member towards its radially outward position. Biasing is in other words pretensioning. Preferably, the spring pressure chamber is arranged at a full bore side of the cylinder system.

Alternatively the nitrogen can be replaced by hydraulic fluid. In that case the gas spring device comprises a hydraulic accumulator in fluid connection with the hydraulic fluid in the spring pressure chamber. This accumulator will store the hydraulic fluid that is pushed out of the cylinder either by external force on the housing and/or body, or by retracting the cylinder hydraulically. Inside the accumulator nitrogen is compressed again which will in that case act as the gas spring.

In an embodiment of the invention, the gas spring device comprises a floating piston at an annular side of the cylinder system which floating piston delimits the spring pressure chamber, and a leaking piston facing the full bore side of the cylinder system, wherein the leaking piston is coupled with a cylinder rod. This enables to have different characteristics for the lifting device with respect to internal operation of the engagement member and external operation of the engagement member. This enables to move the engagement members by an external force and/or an internal force while maintaining biasing the engagement member towards its radially outward position. The external force is applied through the housing and body. The internal force is generated through the gas spring device.

In an embodiment of the invention, the leaking piston comprises a through hole for allowing fluid to flow past the leaking piston. This provides more controlled characteristics with respect to external operation of the engagement member.

In an embodiment of the invention, the leaking piston and the floating piston are configured such that when the floating piston contacts the leaking piston, the floating piston closes off the through hole. This provides controlled characteristics with respect to internal operation of the engagement member.

In an embodiment of the invention, the cylinder system comprises a further pressure chamber opposite the spring pressure chamber, which further pressure chamber contains an hydraulic fluid for retracting the cylinder rod when pressurizing the hydraulic fluid. This enables to operate the engagement member internally. It is noted that upon pressurizing the hydraulic fluid the floating piston moves towards the leaking piston or moves in unity with the leaking piston. The leaking piston may already start moving before the floating piston contacts the leaking piston.

The floating piston, leaking piston and further pressure chamber together enable to provide spring action at the engagement member and active operation of the engagement member while keeping the required hydraulic system simple.

In an embodiment of the invention, the cylinder system is integrated in the body. This provides a compact lifting device with a lower part count.

In an embodiment of the invention, the body and the housing are moveable with respect to each other along the central axis of the lifting device along a housing range of motion and the cylinder rod is provided with a stop for defining an end of the housing range of movement.

The invention is beneficial for different types of lifting devices like a flange lifting tool, an internal lifting tool and an external lifting tool. The engagement member of the flange lifting tool engages a flange of the pipe to provide a form closed connection between the pipe and the lifting device which results in a quick connection. The engagement member of the internal and external lifting tool engages the wall of the pipe by friction to build a frictional connection between the pipe and the lifting device.

It is conceivable that in case of an external lifting tool, the gas spring device comprises a number of cylinder systems which enables that a respective engagement member is associated with a respective cylinder system. These number of cylinder systems may extend outside the housing.

According to a further aspect of the invention, a device is provided comprising one or more of the characterising features described in the description and/or shown in the attached drawings.

According to a further aspect of the invention a method is provided comprising one or more of the characterising features described in the description and/or shown in the attached drawings.

The various aspects discussed in this patent can be combined in order to provide additional advantageous advantages.

DETAILED DESCRIPTION OF EMBODIMENTS

In theFIGS. 1-3an embodiment of the lifting device1according to the invention is shown.

The lifting device1is suitable for picking up a member7from the bottom of the sea.

The lifting device1comprises a central body2. The central body2extending along a central axis20of the lifting device1. The central body is at its trailing end provided with a means11for connection to a hoist cable which is not shown. Here, the central body2is massive however it may also be constructed from plate material.

The lifting device1comprises a housing3. The housing3is configured to be introduced into a cavity21of the member7to be picked up. The housing3accommodates a major part of the body2. Here, the housing3is formed by a cylindrical housing portion3b, a top lid3aand a housing bottom3c. The body2extends through the top lid3a.

The body2and the housing3are moveable arranged with respect to each other along the central axis20of the lifting device1.

The lifting device1comprises an engagement member4. The engagement member4is coupled with the body2and the housing3in such a way that the engagement member4is moveably arranged and moves when the housing3and the body2move with respect to each other. The engagement member4is moveable in a radial direction with respect to the central axis20.

The engagement member4is driven to move in a radial direction in two different ways. Firstly, a direct force F on the engagement member may drive the engagement member4, which is the case during use of the lifting device1. Secondly, the engagement member4may also be driven indirectly by an indirect force applied to the engagement member4through the housing3and the body2. Such an indirect force may be applied to the housing3and the body3from the interior of the lifting device1by a gas spring device5that is described below. It is also conceivable that such an indirect force may be applied to the housing3and the body3from the exterior of the lifting device1.

The engagement member4moves upon movement of the body2and the housing3with respect to each other. The engagement member4is moveably between a radially outward position shown inFIGS. 2 and 3wherein at least a part of the engagement member4extends outside the housing3for contacting the member7to be picked up, and a radially inward position shown inFIG. 1wherein the engagement member4is substantially accommodated within the housing3such that the lifting device1can be introduced in a cavity21of the member7to be picked up.

The body2and the engagement member4comprise cooperating bevelled faces25a,25bto move the engagement member4by wedging action upon movement of the body2and the housing3with respect to each other.

The body2and the housing3are moveable with respect to each other along the central axis20of the lifting device1along a housing3range of motion. Here, the cylinder rod16is provided with a stop19for defining an end of the housing3range of movement as shown inFIG. 6a-6c.

In this case, the engagement member4is hingeably coupled with the body2. The engagement member4is hingeably coupled with the body2at one end4bof the engagement member4. The one end4bof the engagement member is opposite the part4aof the engagement member4which part4aextends outside the housing3for contacting the member7to be picked up.

The lifting device1comprises cooperating guiding means6,9,22,23for guiding the radial movement of the engagement member4. The engagement member4is coupled with the body2and the housing3. The engagement member4is moveably arranged through said cooperating guiding means6,9,22,23. The cooperating guiding means include a guide slot22and a guide pin9. The guide slot22is integrally formed with the engagement member4. The guide pin9is mounted with the housing3. The guide pin9engages the guide slot22and constraints the movement of the engagement member4. The engagement member4is coupled with the body2in a hingeable manner. The engagement member4is coupled with the body2with its one end4b. The engagement member4is coupled with the body2through a hinge joint23. The hinge joint23is supported by the body2through an outward flange24of the body2. The cooperating guiding means6,9,22,23thus constrain the movement of the engagement member4with respect to the mutual movement of the housing3and the body2. When the body2is in an upper position as shown inFIG. 3, an open space10is left below the body2.

The housing3is provided with guiding surfaces6for guiding the engagement member4. In fact these guiding surfaces6do form a framework where the engagement member4extends through when the engagement member4moves between the radially outward position and the radially inward position. The guiding surfaces6are provided in the housing3. The guiding surface6aguides the engagement member4sidewards.

In this case, the lifting device1comprises a plurality of engagement members4. The plurality of engagement members4is arranged around the central axis20for distributing a lifting force FLover a circumference of the lifting device1.

The lifting device1comprises a gas spring device5. The gas spring device5is coupled with the body2and the housing3for biasing the engagement member4towards its radially outward position.

The gas spring device5comprises a cylinder system12,13,15as can be seen inFIGS. 5ato 5cand 6ato 6c. The cylinder system12,13,15has a spring pressure chamber13. The spring pressure chamber13contains a compressible fluid, like compressed nitrogen. The spring pressure chamber13biases the engagement member4towards its radially outward position. In this case, the spring pressure chamber13is arranged at a full bore side of the cylinder system12,13,15.

The gas spring device5comprises a floating piston15. The floating piston is arranged at an annular side of the cylinder system12,13,15. The floating piston15delimits the spring pressure chamber13. The gas spring device5comprises a leaking piston12. The leaking piston12faces the full bore side of the cylinder system12,13,15. The leaking piston12is coupled with a cylinder rod16. The cylinder rod16is coupled with the housing3. The body2is coupled with the housing3through the gas spring device5. Here, the cylinder system12,13,15is integrated in the body2.

The leaking piston12comprises a through hole14for allowing fluid to flow past the leaking piston12. The leaking piston12and the floating piston15are configured such that when the floating piston15contacts the leaking piston12, the floating piston15closes off the through hole14. The floating piston15ensures that the spring action of the gas spring device5is possible in view of the compressible fluid in the spring pressure chamber13and the hydraulic fluid in the further pressure chamber18that is described below.

The cylinder system12,13,15comprises a further pressure chamber18. The further pressure chamber18is arranged opposite the spring pressure chamber13. The pressure chamber18contains an hydraulic fluid for retracting the cylinder rod16when pressurizing the hydraulic fluid. The pressurizing of the hydraulic fluid in the further pressure chamber in turn compresses the fluid in spring pressure chamber13.

When retracting the leaking piston12by an external force, that means here not by pressurizing the hydraulic fluid, the floating piston15detaches from the leaking piston12and an in between chamber17is present as shown inFIG. 5a.

InFIG. 4a-csubsequent states of the lifting device1are shown when the lifting device1contacts an object7to be picked up. First,FIG. 4a, the lifting device contacts a pipe7provided with an internal flange8. The pipe7supports the lifting device1. The weight of the lifting tool1is supported through the engagement member4. The Force F applied therefore on the engagement member4moves the engagement member4from its radially outward position shown towards its radially inward position,FIG. 4b. As a consequence the body2and the housing3start moving with respect to each other. Finally, when the engagement member4has passed the flange8, the gas spring device5forces the engagement member4back towards its radially outward position. The engagement member4now contacts the flange8so that the lifting device can pick up the pipe7. The engagement member4contacts the flange8through its part4athat extends outside the housing3.

WhileFIG. 1-4do show a flange lifting device,FIG. 7shows a schematic cross sectional side view of a further embodiment of the lifting device1according to the invention. The lifting device1is schematically and only partly shown. In general only differences are described compared with the embodiment ofFIG. 1-4. The lifting device1ofFIG. 7is an internal lifting device that engages the interior of the pipe7by friction between the engagement member4and the pipe wall8.

The body2and the engagement member4comprise cooperating bevelled faces25a,25bto move the engagement member4by wedging action upon movement of the body2and the housing3with respect to each other.

FIG. 8shows a schematic cross sectional side view of an even further embodiment of the lifting device1according to the invention. The lifting device1is schematically and only partly shown. In general only differences are described compared with the embodiment ofFIG. 1-4. The lifting device1ofFIG. 8is an external lifting device that engages the exterior of the pipe7by friction between the engagement member4and the pipe wall8. Again, the body2and the engagement member4comprise cooperating bevelled faces25a,25bto move the engagement member4by wedging action upon movement of the body2and the housing3with respect to each other.

It will also be obvious after the above description and drawings are included to illustrate some embodiments of the invention, and not to limit the scope of protection. Starting from this disclosure, many more embodiments will be evident to a skilled person which are within the scope of protection and the essence of this invention and which are obvious combinations of prior art techniques and the disclosure of this patent.