NL2032516B1 - Fallpipe handling system and method therefor - Google Patents

Abstract

The present invention relates to a (flexible) fallpipe handling system for handling, on a vessel, a plurality of bucket strings for assembling a (flexible) fallpipe, the system comprising: 5 - a storage platform comprising a plurality of standpipes each extending from a lower end to an upper end along a longitudinal axis that extends in a substantially perpendicular direction to the storage platform, wherein the lower end of the standpipe is operatively connected to the storage platform, and wherein the upper end of each of the plurality of standpipes is configured to receive thereover an associated bucket 10 string to store the bucket string around the standpipe, and - a crane comprising a pick-up mechanism that is configured to pick up and transport the bucket strings from the standpipes.

Description

FALLPIPE HANDLING SYSTEM AND METHOD THEREFOR

The present invention relates to a fallpipe handling system for handling, on a vessel, a plurality of bucket strings for assembling a flexible fallpipe. The invention further relates to a method for assembling a fall pipe, more specifically a flexible fallpipe, comprising a plurality of bucket strings on a vessel.

Fallpipe handling systems are systems that can handle and assemble fallpipes. Fallpipes are for example used on vessels to provide a passageway for rocks to be deposited onto a pipeline that is arranged on the seabed. Rocks are typically used to protect objects on the seabed against wave slamming, ersosion and/or floating. Flexible fallpipes generally comprise a plurality of buckets strings, wherein each of the bucket strings are operatively connected to each other by means of (steel) wires to form together such fallpipe. The bucket strings, or pre-assembled set(s) of buckets. need to be transported and moved on the vessel by a fallpipe handling system to be added or removed from the total fallpipe-assembly.

A known fallpipe handling system comprises a guide that is positioned along the deck of the vessel in a substantially horizontal direction. On the guide the buckets strings are stored. The guide can act as a conveyor belt to guide the buckets strings towards an opening in the deck of the vessel wherein the buckets strings are positioned to a substantially vertical position. In this way the fallpipe can be assembled and extends from the opening in the deck towards the desired location of the rock. A disadvantage of this system is that it necessitates a large area on the deck to store and handle the bucket strings. Alternative systems require external guidance, a transfer trolley and a separate manipulator to transfer the bucket strings to the moonpool. Disadvantage is the complexity and dependancy due to the need of several machines.

It is an object for the present invention to obviate or at least reduce the abovementioned problems. In particular, it is an object of the present invention to provide a fallpipe handling system that provides an easy handling of the fallpipes during the assembly of the fallpipe.

This object is achieved by a fallpipe handling system for handling, on a vessel, a plurality of bucket strings for assembling a fallpipe, wherein the system comprises: - astorage platform comprising a plurality of standpipes each extending from a lower end to an upper end along a longitudinal axis that extends in a substantially perpendicular direction to the storage platform, wherein the lower end of the standpipe is operatively connected to the storage platform, and wherein the upper end of each of the plurality of standpipes is configured to receive thereover at least one associated bucket string to store the at least one bucket string around the standpipe; and - acrane comprising a pick-up mechanism that is configured to pick up and transport the at least one bucket strings from the standpipes.

An advantage of the invention is that due to the standpipes extending substantially perpendicularly from the storage platform, the bucket strings can be arranged over the standpipes of the storage platform such that the standpipe also extends perpendicularly to the storage platform.

This ensures that the buckets strings can be picked up from the standpipe with a substantially vertical movement. An easy handling of the bucket strings is hereby provided. The easy substantially vertical movement is especially advantageous because the vessel may be subjected to ship motions resulting from waves, such as vaw, pitch and roll movements, and/or varying and/or unevenly distributed loads. The vertical movement provides that even during these ship motions the bucket strings can effectively be handled. This enables handling of the bucket strings in a wider range of operating conditions, thereby increasing the efficiency and reliability of the fallpipe handling system. The fallpipe specifically relates to a flexible fallpipe comprising a number of bucket strings that are assembled together. In the context of the present invention, a reference to a fallpipe specifically relates to a flexible fallpipe.

Another advantage is that, due to the vertical movement of the bucket strings during handling, the amount of rotation of the pick-up mechanism of the crane is also reduced. This allows for a relatively simple construction for the pick-up mechanism, thereby also improving the robustness of the system and reducing the risk of downtimes. Furthermore, the reduced rotation also reduces the chance of undesired movement of the bucket strings, thereby reducing the possibility of damage to the bucket strings or flexible fallpipe due to bumping. Optionally, the crane is a so-called knuckle boom crane.

An even further advantage is that due to the use of a standpipe a plurality of bucket strings can be stored on the same surface area of the deck as the plurality of bucket strings can be slid into gach other. Preferably, each individual standpipe is configured for storing a plurality of bucket strings. This increases the storage capacity of the system according to the invention. Alternatively, or additionally, a smaller surface area of the vessel is needed to store the same amount of bucket strings compared to conventional fallpipe handling systems. For example. each individual standpipe can be configured to store thereon 10 to 20 bucket strings, preferably 12 to 16 bucket strings. The actual number of bucket strings may depend on the local water depth. Furthermore, the system can easily be extended to enable handling more bucket strings. Furthermore, the bucket strings can be manufactured and/or repaired on the standpipe. The buckets can be manufactured from different components, including steel and composites.

In addition, the system according to the invention enables flexible system at limited complexity and cost.

The storage platform can be provided as a dedicated platform. Optionally the storage platform could be the deck of the vessel. In one of the presently preferred embodiments the storage platform is configured to be arranged on the deck of the vessel. The storage platform preferably extends in a substantially horizontal direction.

The bucket strings generally are hollow, such that through their hollow inner space the rocks can be allowed to passage. Due to the bucket strings being hollow, the bucket strings can effectively be placed over the standpipes. The bucket strings are, in a storage position, preferably positioned around the standpipes, wherein the standpipes extend through the hollow part of the bucket strings.

In an embodiment according to the invention each of the plurality of standpipes comprises a circumferential wall, wherein the bucket strings are configured to be positioned over the circumferential wall of the standpipe.

An advantage of the circumferential wall of the standpipe is that the bucket strings, which are hollow, can effectively be positioned against the circumferential wall. This inhibits significant (undesired) movement of the bucket strings when stored on or over the standpipes. Preferably, the circumferential inner wall of the hollow bucket string is at least partly in contact with the outer circumferential wall of the standpipe in the storage position. The buckets strings are preferably positioned over the circumferential wall of the standpipe in a storage position.

In an embodiment according to the invention the standpipe is cylindrically shaped.

The cylindrical shape provides a preferably even surface without edges or ridges on the circumferential wall of the standpipe. Another advantage is that the cylindrical shape is complementary to the substantially cylindrically shaped bucket strings.

In an embodiment according to the invention the standpipe is substantially hollow and comprises an opening at the upper end of the standpipe and an inner space that is positioned along and around its longitudinal axis, wherein the inner space is connected to the opening.

In an embodiment according to the invention the inner space is configured to receive at least a part of the pick-up mechanism.

The mner space is configured to receive at least part of the pick-up mechanism through its opening at the upper end. Due to the inner space the part of the pick-up mechanism that enters the inner space can function as a guiding tool for the pick-up mechanism. In this way it is ensured that the pick-up mechanism positions itself correctly over the bucket strings, such that a correct pick-up of the bucket strings is realized. A safe handling of the bucket strings is thereby achieved.

In an embodiment according to the invention the storage platform is configured to be arranged on the deck of the vessel.

By being arranged on the deck of the vessel the bucket strings can be stored on the deck and be picked up by the crane to a desired location to arrange the fallpipe. Another advantage of the storage platform being configured to be arranged on the deck of the vessel is that the storage platform can be exchanged between different vessels. Alternatively, or additionally, the storage platform can be removed from a vessel such that the vessel can be used for other operations.

In an embodiment according to the invention the upper end of the standpipe is slanted towards the longitudinal axis of the standpipe.

Preferably, the upper end of the standpipe is slanted from the circumferential wall towards the longitudinal axis. The angle of the slanted surface may be in the range of 5-30 degrees.

An advantage of the slanted upper end of the standpipe is that during the positioning of the bucket strings over the standpipes the upper end becomes self-searching. In particular, when the longitudinal axis of the bucket string is not positioned exactly vertically centred above the longitudinal axis of the standpipe, the slanted upper end guides the bucket strings towards a position wherein the longitudinal axes more closely coincide. This reduces the time necessary to store the bucket strings onto the standpipes.

In a further embodiment according to the invention the pick-up mechanism comprises an elongated element that in use extends in a first direction that is substantially parallel to the longitudinal axis of the standpipes, and further comprises a gripper element that is operatively connected to the elongated element and is movable in the first direction, wherein the pick-up mechanism has a pick-up position wherein the gripper element 1s at least partly positioned over the standpipe. The gripper element may comprise a latching mechanism. In certain embodiments of the system according to the present invention the gripper may engage 1 to 15 bucket strings at once.

In this embodiment the pick-up mechanism is operatively connected to the crane. The gripper element is configured to grip or hold the bucket string. The first direction is substantially parallel to the longitudinal axis of the elongated element. The crane is then capable of moving and positioning the bucket string at the desired location. An advantage of such configuration is that the crane can also be used for other operations. In fact, no specific crane is essential for the system of the present invention.

In an embodiment according to the invention the pick-mechanism comprises a center element that is movably connected in the first direction to the elongated element, wherein the center element is fixedly or operatively connected to the gripper element such that a movement of the center element in the first direction results in a movement of the gripper element in the first direction.

The center element is movably attached to the elongated element such that an easy movement in the first direction is made possible. In a presently preferred embodiment the gripper element is directly or indirectly attached to the center element such that a movement of the center element relative to the elongated element in the first direction results in a (joint) movement of the gripper element relative to the elongated element in the first direction. Optionally, the center element is coaxially provided over the elongated element.

An advantage of the center element is that it can function as a guide for positioning the pick-up mechanism relative to the bucket strings.

In an embodiment according to the invention the center element has an elongated shape. and wherein in the pick-up position the center element is positioned in the inner space of the 5 standpipe.

Optionally, the center element is for example a tubular element coaxially positioned around the elongated element. Due to the center element having an elongated shape it is easily provided in the inner space of the standpipe. which preferably has a corresponding elongated shape. This provides an effective guiding of the gripper element around the bucket string.

Alternatively, or additionally, it ensures that the gripper is correctly and easily positioned around the bucket string.

In a further embodiment according to the invention the system further comprises a second crane that is configured to pick up and transport the bucket strings from the standpipe.

The second crane preferably is similar or identical to the first crane, and at least comprises a pick-up mechanism as described for previous embodiments. Due to the second crane a larger area can be used to arrange the standpipes. Furthermore, this increases the overall capacity and provides a more redundant system.

In an even further embodiment according to the invention a length of the standpipes as measured along its longitudinal axis is in the range of 1-10 metres, preferably in the range of 2-5 metres, and most preferably in the range of 3-4 metres.

The abovementioned lengths provide an adequate height to store the bucket strings over the standpipes.

In an embodiment according to the invention the system further comprises a plurality of bucket strings that are configured to be stored around an associated standpipe.

The bucket strings can effectively be stored over the standpipes, and in a next step being transported from the standpipes to an opening in the ship, wherein at the opening the fallpipe can be constructed/assembled from the bucket strings. The bucket strings are preferably substantially cylindrically shaped with a diameter at the top opening slightly larger than the diameter at the bottom opening. In this way a funnel-like structure is obtained wherein a plurality of bucket strings can be slid into each other.

Optionally, the system is provided with a controller to enable automated bucket string handling when assembling a fallpipe for subsea rock installation.

The invention further relates to a vessel provided with a system according to any one of the foregoing embodiments.

The vessel provides similar effects and advantages as described for the system.

The invention further also relates to a method for assembling a fall pipe comprising a plurality of bucket strings on a vessel, comprising: - providing a system according to the invention or a vessel according to the invention: - picking up the bucket strings from the standpipes; and - moving the bucket string to a desired location.

The method provides similar effects and advantages as described for the system and the vessel.

In an embodiment according to the invention picking up the bucket strings of the standpipes comprises: - moving the pick-up mechanism above the standpipe such that the elongated element is in line with the longitudinal axis of the standpipe; - moving a center element downwards such that a gripper element is in a pick-up position around the standpipe; - attaching the gripper element to the bucket string that is stored around the standpipe: and - moving the center element upwards to remove the bucket string from the standpipe.

The invention further relates to the use of a system according to the invention, a vessel according to the invention or a method according to the invention for depositing rock on an underwater pipe to stabilize the pipe, also referred to as subsea rock installation. Such underwater pipe can be at 1500 m below sea level, for example.

The use of the system, vessel or the method provides similar effects and advantages as described for the system, the vessel and the method.

Further advantages, features and details are elucidated on the basis of preferred embodiments thereof, wherein reference is made to the accompanying drawings, wherein: - figures 1A-B illustrate a top view of a vessel according to the invention; - figure 2 illustrates a side view of a vessel according to the invention; and - figure 3-6 illustrate examples of stages of lifting a bucket string from a standpipe.

Vessel 2 (figures 1A-B) comprises deck 4 whereon (flexible) fallpipe handling system 6 is provided. System 6 comprises standpipes 8 whereon bucket strings 10 are stored. System 6 is furthermore provided with two cranes 9, wherein each of the cranes is configured to pick up bucket strings 10 from standpipes 8. Standpipes 8 are arranged on storage platform 12, wherein storage platform 12 is provided on deck 4. Storage platform 12 stretches out in a plane whereon standpipes 8 are substantially perpendicularly provided. Cranes 9 are further configured to transport bucket strings 10 from standpipe 8 to moonpool 14. Moonpool 14 is an opening that is provided in deck 4 and reaches through the bottom of vessel 2. In this way a fallpipe that is constructed from bucket strings 10 can be provided through moonpool (opening) 14 towards the seabed. Further provided on vessel 2 in the illustrated embodiment are rocks 20. Bucket strings 10 are in the illustrated embodiment substantially cylindrically shaped with a slightly wider diameter at the top opening than the bottom opening such that a funnel-like structure is obtained.

Vessel 2 (figure 2) comprises deck 4 through which moonpool 14 is provided. On top of deck 4 above moonpool 14 fallpipe assembly system 16 is arranged that is configured to assemble bucket strings 10 into fallpipe 18. Fallpipe 18 comprises plurality of bucket strings 10 and is provided to allow the deposit of rocks 20, using ROV 21, on pipeline 22 that is positioned on seabed 24.

Cranes 9 comprise pick-up mechanism 26 that is configured to grip bucket strings 10.

Standpipe 8 is configured to store a plurality of bucket strings 10 that are slid into each other. In this way more bucket strings 10 can be stored on a single standpipe 8, which increases the storage capacity of system 2 such that it can provide a longer fallpipe 18.

Standpipe 8 (figure 3) is arranged on storage platform 12. Standpipe 8 is cylindrically shaped and comprises circumferential wall 36. Standpipe 8 extends in longitudinal direction L that is substantially perpendicular to storage platform 12. Lower end 28 of standpipe 8 is arranged on storage platform 12 and upper end 30 comprises standpipe opening 32. Standpipe opening 32 provides access to inner space 34 of standpipe 8. Inner space 34 is positioned substantially concentrical around longitudinal axis L. Upper end 30 further is provided with slanted surface 38.

Slanted surface 38 has angle a of about 70 degrees with respect to circumferential wall and is slanted towards longitudinal axis L. Bucket strings 10 are stored around standpipe 8, such that inner circumferential wall 40 contacts circumferential wall 36 of standpipe 8 in order to prevent movement of bucket strings 10 relative to standpipes 8 when vessel 2 moves.

Pick up mechanism 26 comprises elongated element 42 that is attached with hinge axis 44 to crane 9. In the illustrated embodiment pick-up mechanism 26 also comprises leveling system 46 that comprises cylinder 48 that is positioned between hinge axis 50 operatively attached to crane 9 and hinge axis 52 operatively attached to attachment member 54. Cylinder 48 of leveling system 46 can be used to hinge elongated element 42 around hinge axis 44 in order to bring elongated element 42 in its desired position. Elongated element 42 is in the illustrated embodiment a cylindrical element. Coaxially positioned around elongated clement 42 is center element 56. Center element 56 is movably attached to elongated element 42. Fixed to center element 56 is gripper or gripper element 58. Gripper 58 comprises two side bars 60a, 60b that are positioned on opposite sides of center element 56 and extend substantially parallel to center element 56 and elongated element 42. Cross bars 61a, 61b are operatively connected between side bars 60a, 60b and fixed to center element 56. At lower ends 62a, 62b of side bars 60a, 60b latching system 64 is arranged.

Latching svstem 64 comprises cylinder 66 that is connected between side bar 60a, 60b and latch element 68. Latch element 68 is rotatably connected to side bar 60a, 60b around rotation axis 69. A contracting movement of cylinder 66 provides a movement of engagement edge 70 towards center element 56. In the illustrated embodiment the axis of center element 56 is positioned in ling with longitudinal axis L of standpipe 8.

Center element 56 (figure 4) is moved downwards relative to its position illustrated in figure 3 in a direction substantially parallel to longitudinal axis L. In fact, center element 56 is moved downwards relative to elongated element 42. Center element 56 is thereby provided in opening 32 and inner space 34 of standpipe 8.

Center element 56 (figure 5) is moved further downwards relative to its position in figure 3, such that center element 56 almost completely fills inner space 34 of standpipe 8. Pick up mechanism 26 is then in pick up position 74. In pick up position 74 gripper 58 substantially surrounds plurality of bucket strings 10. Cylinder 66 of latching system 64 is contracted such that latch element 68 is rotated towards center element 56 and thus towards lowest bucket string 10 of plurality of bucket strings 10. In this way engagement edge 70 of latch element 68 is positioned against lowest bucket string 10 such that engagement edge 70 can come into contact with engagement ridge 72 that is provided on bucket string 10.

Center element 56 (figure 6) is moved upwards by moving over elongated element 42. As latching system 64 engages on lowest bucket string 10 plurality of bucket strings 10 is effectively lifted from standpipe 8. Crane 9 can then move plurality of bucket strings 10 towards fallpipe handling system 16 such that fallpipe 18 can be assembled from plurality of bucket strings 10. It will be understood that it would also be possible to remove only some of the plurality of bucket strings 10 in a single transportation movement.

The present invention is by no means limited to the above-described preferred embodiments thereof. The rights sought are defined by the following claims within the scope of which many modifications can be envisaged.

Claims (17)

CONCLUSIONS I. Downcomer handling system for handling a plurality of bucket parts on a vessel for assembling a downcomer. the system comprising: - a storage platform comprising a plurality of standpipes, each standpipe extending from a lower end along a longitudinal axis extending in a substantially perpendicular direction to the storage platform to an upper end, the lower end of the standpipe is operatively connected to the storage platform, and wherein the upper end of each of the plurality of standpipes is arranged to receive at least one associated bucket part thereover for storing the at least one bucket part around the standpipe; and - a crane comprising a picking mechanism that is adapted to pick up and transport the at least one bucket part. 2. System according to claim 1, wherein each of the plurality of standpipes comprises a circumferential wall, wherein the bucket parts are designed to be positioned over the circumferential wall of the standpipe. 3. System according to any one of the preceding claims, wherein the standpipe is cylindrical in shape. 4. System according to any of the preceding claims, wherein the standpipe is substantially hollow and at the upper end of the standpipe comprises an opening and an inner space positioned around the longitudinal axis, wherein the inner space is connected to the opening. 5. System according to claim 4, wherein the interior space is designed to receive at least part of the picking mechanism. 6. System according to any of the preceding claims, wherein the storage platform is designed to be placed on the deck of the vessel. 7. System according to any of the preceding claims. wherein the upper end of the standpipe is oriented obliquely towards the longitudinal axis of the standpipe. 8. System according to any of the preceding claims, wherein the crane comprises a pick-up mechanism for picking up bucket parts, wherein the pick-up mechanism comprises an elongated element that in use extends in a first direction that is substantially parallel to the longitudinal axis of the standpipes further comprising a gripper element operatively connected to the elongated element and movable in the first direction, the pick-up mechanism having a pick-up position in which the gripper element is positioned over the standpipe. 9. System according to claim 8, wherein the picking mechanism comprises a middle element that is movably connected in the first direction to the elongated element, wherein the middle element is fixedly connected to the gripping element such that a movement of the middle element in the first direction results in a movement of the gripping element in the first direction. 10. System according to claim 9, wherein the middle element has an elongated shape, and wherein in the pick-up position the middle element is positioned in the inner space of the standpipe. 11. System according to any of the preceding claims, further comprising a second crane that is designed to pick up and transport the bucket parts of the standpipe. 12. System according to any of the preceding claims, wherein the length of the standpipes measured along the longitudinal axis is in the range of 1-10 meters, preferably in the range of 2-5 meters, and most preferably in the range range of 3-4 meters. A system according to any one of the preceding claims, further comprising a plurality of bucket parts adapted to be stored around an associated standpipe. 14. Vessel provided with a system according to any of the preceding claims. 15. Method for assembling a fall pipe comprising a plurality of bucket parts on a vessel, comprising: - providing a system according to any one of claims 1-13 or a vessel according to claim 14; and - picking up the bucket parts from the standpipes; and - moving the bucket parts to a desired location. 16. Method according to claim 15, wherein picking up the bucket parts from the standpipes comprises: - moving the picking mechanism up the standpipes such that the elongated element is in line with the longitudinal axis of the standpipe; - moving a center element downwards such that a gripping element is in a picking position around the standpipe; - attaching the gripping element to the bucket part stored around the standpipe; and - moving the middle element upwards to remove the bucket part from the standpipe. 17. The use of a system according to any one of claims 1-13, a vessel according to claim 14 or a method according to claim 15 or 16 for applying stones to an underwater pipe for stabilizing the pipe.