System and method for subsea assembly of a guide cone on a manifold hub

Abstract

A system and method for the subsea assembly of a guide cone on a manifold HUB, useful in instances where it is necessary to reassemble guide cones in manifolds that are already installed on the seabed, allowing for the use of a manifold HUB that had become inoperative due to the impossibility of performing a new DVC (Direct Vertical Connection) operation. The system and method are application to subsea maintenance, more specifically the decommissioning of flexible pipelines and the assembly of subsea equipment.

Description

RELATED APPLICATION DATA

[0001] This application is based on and claims priority to Brazilian Application No. BR 10 2025 004781 0, filed on Mar. 13, 2025, the entire contents of which are incorporated herein by reference.FIELD OF THE INVENTION

[0002] The present invention is within the technical field of oil and gas, in particular subsea maintenance, more specifically the decommissioning of flexible pipelines and the assembly of subsea equipment, and refers to a system and method for the subsea assembly of a guide cone on a manifold HUB. The present invention can be applied when it is necessary to reassemble guide cones on manifolds that are already installed on the seabed.BACKGROUND OF THE INVENTION

[0003] In the context of subsea operations, during the decommissioning of flexible pipelines that connect oil wells to production units, or to subsea manifolds, problems may arise during the DVC (Direct Vertical Connection) and DVD (Direct Vertical Disconnection) operations.

[0004] Currently, interconnections are made through the Vertical Connection Module (VCM), which is a device that can connect the flexible pipeline to the Christmas tree, a manifold, or even another rigid pipeline. For the purpose of facilitating the positioning of the VCM on the target and to provide greater maneuverability, the operation known as Direct Vertical Connection (DVC) is often performed first with a second-end pull-in.

[0005] Similarly, the DVD disconnection operation is the process of disconnecting equipment performed in the subsea environment. Just like direct vertical connections, direct vertical disconnections can be performed at the first end or at the second end. In these instances, the guide cone may become detached from the HUB, preventing a new DVC operation on that HUB, which can lead to significant financial losses.

[0006] During the pull to dislodge the VCM (Direct Vertical Connection Module) for repositioning, resistance to the upward vertical movement may occur, leading to an abrupt uncoupling of the VCM (Direct Vertical Connection Module). As a consequence of this motion, the guide cone (Guide Cone Weldment) and a two-part piece can detach from the HUB and be projected towards the seabed.

[0007] When the manifold is assembled at the factory, the guide cones that protect the HUB are positioned and secured to remain in place until the end of the equipment's service life. However, it was never intended to be removed and installed in subsea operations.

[0008] Thus, in order to solve the aforementioned technical problems, the present invention proposes a Subsea Guide Cone Weldment System and Method in a Manifold HUB. The method reinstalls the guide cone in the manifold, but in a completely diverless manner (without the need for divers). Thus, the present invention makes it possible to rebuild the guide cone in the manifold in a completely underwater and diverless manner.STATE OF THE ART

[0009] Document KR20140078951A is part of the general state of the art and describes a method for installing a manifold in a deep sea suction pile, aiming to optimize the process and solve common issues related to the observation and alignment during installation. The manifold is placed over a flange of the suction pile, and a guide cone located at the base of the manifold receives the guide post to ensure proper alignment. On the other hand, the present invention is more related to assembling part of the HUB guide cone onto a manifold that is already installed and operating.

[0010] In turn, document WO1999023350A1 describes a method for mounting a seabed installation, such as a drilling template and a manifold. After alignment and contact, the manifold is lowered relative to the guide post, completing the installation. It should be noted that the method described in the aforementioned document further refers to mounting the manifold on the seabed, and the present invention proposes a system for mounting a guide cone on the HUB of a manifold that is already installed and in operation.

[0011] Document CN109098692B covers a method of installing an underwater suspension manifold, consisting mainly of a cluster type manifold body and a buoy arranged at the bottom of the manifold. It should be noted that this approach overcomes the limitations of traditional methods, which only allow the installation of manifold systems attached to the seabed. It should be noted once again that this document focuses on the assembly of the manifold itself, and does not relate to the assembly of the guide cone, as is the case in the present invention.

[0012] Finally, document WO2001025083A1 is also part of the general state of the art and covers a method for positioning subaqueous articles and provides a solution for aligning equipment that is lowered from the ocean surface. The invention provides for the use of a thrust assembly including two thrust units mounted on opposite ends of a metal pipe which is suspended in water by lifting rigging. It should be noted that the aforementioned document is more related to a subsea alignment system operated with hydraulic thrusts for large-scale subsea movements, unlike the present invention which aims at mounting the guide cone of the manifold HUB.

[0013] It is also important to highlight that the present invention offers advantages considering the economic and productivity impact, which is associated with the fact that it enables the use of a manifold HUB that had become inoperative due to the impossibility of performing a new DVC (Direct Vertical Connection) operation.BRIEF DESCRIPTION OF THE INVENTION

[0014] The present invention refers to subsea maintenance, more specifically the decommissioning of flexible pipelines and the assembly of subsea equipment, and refers to a system and method for the subsea assembly of a guide cone on a manifold HUB. The present invention finds use in instances where it is necessary to reassemble guide cones in manifolds that are already installed on the seabed, allowing for the use of a manifold HUB that had become inoperative due to the impossibility of performing a new DVC (Direct Vertical Connection) operation.BRIEF DESCRIPTION OF THE FIGURES

[0015] To provide a comprehensive and full view of the goal of the present invention, the figures are presented below, which are referred to as follows.

[0016] FIG. 1 schematically depicts the split ring, according to a preferred embodiment of the present invention.

[0017] FIG. 2 shows schematically the split plate with special nuts placed to guide the screws, according to a preferred embodiment of the present invention.

[0018] FIG. 3 schematically represents the mechanism for positioning the guide cone in the HUB, according to a preferred embodiment of the present invention.

[0019] FIG. 4 (4a, 4b and 4c) schematically represents the ROV support table located near the HUB in different views, according to a preferred embodiment of the present invention.

[0020] FIG. 5 schematically represents the ROV mounting the guide cone on the HUB, according to a preferred embodiment of the present invention.

[0021] FIG. 6 shows the mechanism for placing the guide cone in the HUB, highlighting the regions where screws should not be mounted.

[0022] FIG. 7 shows the mechanism for placing the guide cone in the HUB, highlighting the tie rods that hold the tabs of the split ring.

[0023] FIG. 8 shows the HUB capped with a protective cap.

[0024] FIG. 9 shows the mechanism for positioning the guide cone in the HUB, highlighting the release of the shackles.

[0025] FIG. 10 shows the procedure for installing hex socket screws (Allen).

[0026] FIG. 11 shows the torque sequence for the screws.DETAILED DESCRIPTION OF THE INVENTION

[0027] The present invention relates to a system and method for underwater mounting a guide cone on a manifold HUB. The system comprises a split ring, a split plate, a mechanism for positioning the guide cone on the HUB, and a support table for the ROV, which is located near the Manifold HUB.

[0028] The split plate holds the split ring, the mechanism for positioning the guide cone on the HUB centers the guide cone for subsequent attachment of the split ring. The ROV support table is used for docking the ROV.

[0029] As shown in FIG. 1, the split ring comprises two main parts, each part comprising at least four special nuts equally spaced at an angle of preferably 45°. Positioning of the nuts is important as they serve as a guide for placing the split ring (this component locks the guide cone to the HUB groove).

[0030] The nuts can be 1″ hexagonal and can be made of steel. As shown in FIG. 2, the split plate of the mounting device includes recesses to assist in the correct placement of the split ring and subsequent connection of the special nuts.

[0031] The split plate comprises two shafts at the ends, which are directed outwards from the plate and serve to fit the wrench and can be manufactured from SAE 1045 steel. The split plate further includes support elements (shown in green) to assist in securing the guide cone (“panelão”), at least four padeyes (elements shown in green with a central opening and at least four guide cone bracing elements (elements shown in blue).

[0032] The split plate further includes four openings at opposite ends for attaching bottom screws, which may be 1″×138 hex socket c-c screws (Allen). The positioning mechanism on the HUB comprises a guide cone (“panelão”), as shown in FIG. 3, a master link ring to which the vessel winch is connected, and a four-leg sling to assist in maneuvering the assembly.

[0033] The guide cone comprises four T-shaped elements arranged in its interior and has openings at its bottom having the same configuration as the split ring, thereby allowing them to be bolted together. The support table for the ROV, as shown in FIG. 4a, can be 2 meters high and include central openings.

[0034] In general, the method of subsea mounting of a guide cone on a manifold HUB comprises the following steps:

[0035] (a) installing the Teflon cover on the HUB, wherein a RSV vessel (ROV Support Vessel) installs it in the subsea environment via ROV at the manifold hub,

[0036] (b) coupling the Guide Cone on the HUB and disconnecting the sling and buoys, wherein the RSV vessel is connected to its crane cable with the four-leg sling and masterlink ring,

[0037] (c) tightening the Guide Cone Centering Screws with the Split Ring, where the ROV places the guide cone centering mechanism on the HUB, tightening the first and second stroke screws of the split ring,

[0038] (d) aligning the Guide Cone Openings and the Split Ring, wherein the alignment of the split ring with the guide cone is permitted from two spindles installed on the base of the mechanism,

[0039] (e) placing screws and applying torque, wherein the screws inside the guide cone (“panelão”) are positioned in the openings using a magnetic tool and subsequently torqued with a hydraulic torque wrench attached to a handle designed for each position,

[0040] (f) removal of the system, where the entire system used for mounting and centering the guide cone and HUB is removed, and

[0041] (g) removal of the Teflon cover, at which point the HUB is ready for a new DVC. Detail of the special nuts mounted on the split ring.

[0042] Due to difficulty of access, the torques applied were from (244N.m initial) to (519 N.m final), according to the torque procedure.

[0043] More specifically, the method first comprises a step of “preparing the tools required for performing the activities” (step 1), in which buoyancy devices are installed on all equipment and tools that are handled by the ROV, where necessary (e.g., a nylon rope monkey fist with a minimum length of 400 mm, to assist in the retrieval of such equipment in the event that it becomes detached and falls onto the seabed). Preparation of the hub protection device is also carried out in the ROV tool tray. If required, the device is lowered in the tool basket via the vessel crane.

[0044] Thereafter, the step of “placing the guide cone on the installation device for lowering together with its deployment sling” is carried out (step 2). A transfer strap or sling is provided on the masterlink ring of the device deployment sling, as it will be used to transfer the buoyancy force from the buoy to the dead weight at a later stage.

[0045] Length of the strap to be used must be verified on-site during the survey stages (inspection). Due to the equipment weighing over 100 kg in the water, the onboard crew should assess the need to install the accessory using flotation devices to neutralize its weight. If necessary, a lifting strop should be attached to the upper end of the equipment for installing the buoy so that it is lowered at the proper installation position.

[0046] Attention should be paid to the following points during preparation of the device prior to deployment to the working depth: 1) Refrain from assembling the screws at the positions indicated in FIG. 6, as this side will be on the back of the HUB; 2) The parts indicated in FIG. 1 act as stoppers, aligning the openings of the guide cone with the nuts of the split ring, where they will be bolted to secure the HUB; 3) Attention should be paid to the correct placement of the nuts, as they will serve as a guide for positioning the split ring, as shown in FIG. 2; 5) Attention should be paid to the tie rods securing the tabs of the split ring, as shown in FIG. 7; 6) Attention should be paid to the upper centering screws that should be lowered while mounted on the guide cone, as shown in FIG. 3.

[0047] The next step is to “Surveying (inspecting) and locating the points of interest according to the coordinates” (step 3). During the survey, the vessel must assess whether there is any interference near the operation site. If any obstruction is identified that could hinder or prevent the operation, the crew must assess it and record it in a report. If necessary, the survey may be extended to other locations to ensure safety and the proper execution of the operation.

[0048] Next, the step of “Assessing a clear area on the seabed near the operation site for positioning the concrete mooring anchor and dead weight” is carried out (step 4). Thereafter, the step of “performing metrology on the MSIAG to confirm the height of the equipment HUB relative to the seabed” (step 5) is performed. This information is important so that the table can be adjusted to the optimal height for the vehicle to operate. Metrology can be performed using a graduated ruler or other resource available on board the vessel.

[0049] In step 6, the “preparation and lowering of the ROV table, and its positioning near MSIAG-FC-014 such that the vehicle can operate at the equipment HUB,” is carried out. The table should be lowered at the proper height required for operation with the ROV. In step 7, using the vessel winch or crane, a concrete mooring anchor is lowered and placed on the seabed near the operation site.

[0050] In step 8, using the vessel winch or crane, the device is deployed together with the guide cone and placed on the concrete mooring anchor. After the placement of the device, the crane cable is released. Due to the equipment weighing over 100 kg in the water, the onboard crew should assess the need to install the accessory using flotation devices to neutralize its weight.

[0051] If necessary, a lifting strop should be attached to the upper end of the equipment for installing the buoy so that it is lowered at the proper installation position. The use of 600 kg of buoyancy force is suggested; however, the vessel crew may determine the required amount. If the onboard crew deems it more appropriate to deploy the equipment without the buoy and to transfer the required buoyancy force at the sea bottom, this may also be performed. There is also the need to assess the use of the vessel heave when positioning the equipment over the mooring anchor and the HUB.

[0052] In step 9, with the ROV at the working depth resting on the table, the mouth of the HUB should be capped with the protective cap available on board, as shown in FIG. 8. After positioning the protective cap on the HUB, the ROV should pick up the installation device along with the guide cone and move towards the table.

[0053] With the ROV properly supported on the table and aligned, the installation device should be fit onto the equipment HUB. If the equipment is being positioned using the vessel's crane, the heave compensator must be engaged at all times. After positioning, crane cable should be released.

[0054] After positioning the guide cone over the HUB, the dead weight should be deployed and placed on the seabed near the operation site. Next, the float buoyancy is transferred to the deadweight slowly and gradually, so as not to damage the equipment. A strap or sling may be used with the transfer attachment. Once the transfer strap or sling is properly attached to the dead weight, the 12.5-ton shackles should be released, and the tie rods securing the tabs of the split ring should be cut and removed.

[0055] Accordingly, as soon as the shackles are gradually released, the buoyance force will be transferred to the dead weight, as shown in FIG. 9. After removing the buoy along with the guide cone deployment sling, they should be retrieved to the deck.

[0056] After completing the previous steps, using the wrench, the tabs of the split ring must be brought together, attaching the guide cone to the HUB. They shall be bolted by aligning the holes of the ring and the guide cone. A 1 ⅝″ hexagonal wrench is used, as shown in FIG. 5.

[0057] Next, the step of “checking or inspecting whether the openings in the guide cone are at the same position as the split ring” should be carried out. After confirming that the accessory openings are correctly drilled, the 1″ Hex socket screws should be installed to secure the guide cone, as shown in FIG. 10. A wrench with a ¾″ magnetized Allen key adapter and a 1″ Hex socket screw should be used.

[0058] After completing the installation of all Hex socket screws, they should be torqued using the RSL-2 Hex Link 1 ⅝″ torque wrench with a ¾″ Hex socket key adapter, as shown in FIG. 11. First stage of torque application on studs 2 and 3:244 Nm (1400 psi on RSL-2). 2nd Torque Phase on studs 1 and 4:519 Nm (2800 psi on RSL-2). 3rd Torque Phase on studs 7 and 6:244 Nm (1400 psi on RSL-2). 4th Torque Phase on studs 8 and 5:519 Nm (2800 psi on RSL-2). 5th Torque Phase in all studs (from 1 to 8) sequentially with 519 Nm (2800 psi on RSL-2).

[0059] After completing the torque procedure, the two centering screws must be removed and stored in the ROV tray or tool basket.

[0060] Based on the previous disclosure, it is evident that the methodology created makes it possible to install the split cone using a completely diverless underwater operation. This new methodology enabled the maintenance and recovery of a manifold HUB that was previously inoperative, allowing connection of the platform export gas pipeline and resulting in significant financial gains.

[0061] The present invention takes advantage of the access constraints to the subsea structure and a scenario modeling, which allowed the design of special tools to reach the points of interest. In addition, a removable assembly system was developed to enable the precise installation of the guide cone at the specified location. To enable fastening without using welds, a special nut was created that allowed the guide cone to be centered with the split ring.

[0062] The present invention deals with the proper application of commercially available instruments and tools that have been assertively selected, as well as the knowledge of subsea assembly processes carried out by specialized vessels. Thus, a method was created with predefined steps that must necessarily be carried out in order for the assembly requirements to be met.

[0063] Those skilled in the art will value the knowledge presented herein and may reproduce the invention in the disclosed embodiments and other variants thereof, as covered by the scope of the appended claims.

Examples

Embodiment Construction

[0027]The present invention relates to a system and method for underwater mounting a guide cone on a manifold HUB. The system comprises a split ring, a split plate, a mechanism for positioning the guide cone on the HUB, and a support table for the ROV, which is located near the Manifold HUB.

[0028]The split plate holds the split ring, the mechanism for positioning the guide cone on the HUB centers the guide cone for subsequent attachment of the split ring. The ROV support table is used for docking the ROV.

[0029]As shown in FIG. 1, the split ring comprises two main parts, each part comprising at least four special nuts equally spaced at an angle of preferably 45°. Positioning of the nuts is important as they serve as a guide for placing the split ring (this component locks the guide cone to the HUB groove).

[0030]The nuts can be 1″ hexagonal and can be made of steel. As shown in FIG. 2, the split plate of the mounting device includes recesses to assist in the correct placement of the s...

RELATED APPLICATION DATA

[0001] This application is based on and claims priority to Brazilian Application No. BR 10 2025 004781 0, filed on Mar. 13, 2025, the entire contents of which are incorporated herein by reference.FIELD OF THE INVENTION

[0002] The present invention is within the technical field of oil and gas, in particular subsea maintenance, more specifically the decommissioning of flexible pipelines and the assembly of subsea equipment, and refers to a system and method for the subsea assembly of a guide cone on a manifold HUB. The present invention can be applied when it is necessary to reassemble guide cones on manifolds that are already installed on the seabed.BACKGROUND OF THE INVENTION

[0003] In the context of subsea operations, during the decommissioning of flexible pipelines that connect oil wells to production units, or to subsea manifolds, problems may arise during the DVC (Direct Vertical Connection) and DVD (Direct Vertical Disconnection) operations.

[0004] Currently, interconnections are made through the Vertical Connection Module (VCM), which is a device that can connect the flexible pipeline to the Christmas tree, a manifold, or even another rigid pipeline. For the purpose of facilitating the positioning of the VCM on the target and to provide greater maneuverability, the operation known as Direct Vertical Connection (DVC) is often performed first with a second-end pull-in.

[0005] Similarly, the DVD disconnection operation is the process of disconnecting equipment performed in the subsea environment. Just like direct vertical connections, direct vertical disconnections can be performed at the first end or at the second end. In these instances, the guide cone may become detached from the HUB, preventing a new DVC operation on that HUB, which can lead to significant financial losses.

[0006] During the pull to dislodge the VCM (Direct Vertical Connection Module) for repositioning, resistance to the upward vertical movement may occur, leading to an abrupt uncoupling of the VCM (Direct Vertical Connection Module). As a consequence of this motion, the guide cone (Guide Cone Weldment) and a two-part piece can detach from the HUB and be projected towards the seabed.

[0007] When the manifold is assembled at the factory, the guide cones that protect the HUB are positioned and secured to remain in place until the end of the equipment's service life. However, it was never intended to be removed and installed in subsea operations.

[0008] Thus, in order to solve the aforementioned technical problems, the present invention proposes a Subsea Guide Cone Weldment System and Method in a Manifold HUB. The method reinstalls the guide cone in the manifold, but in a completely diverless manner (without the need for divers). Thus, the present invention makes it possible to rebuild the guide cone in the manifold in a completely underwater and diverless manner.STATE OF THE ART

[0009] Document KR20140078951A is part of the general state of the art and describes a method for installing a manifold in a deep sea suction pile, aiming to optimize the process and solve common issues related to the observation and alignment during installation. The manifold is placed over a flange of the suction pile, and a guide cone located at the base of the manifold receives the guide post to ensure proper alignment. On the other hand, the present invention is more related to assembling part of the HUB guide cone onto a manifold that is already installed and operating.

[0010] In turn, document WO1999023350A1 describes a method for mounting a seabed installation, such as a drilling template and a manifold. After alignment and contact, the manifold is lowered relative to the guide post, completing the installation. It should be noted that the method described in the aforementioned document further refers to mounting the manifold on the seabed, and the present invention proposes a system for mounting a guide cone on the HUB of a manifold that is already installed and in operation.

[0011] Document CN109098692B covers a method of installing an underwater suspension manifold, consisting mainly of a cluster type manifold body and a buoy arranged at the bottom of the manifold. It should be noted that this approach overcomes the limitations of traditional methods, which only allow the installation of manifold systems attached to the seabed. It should be noted once again that this document focuses on the assembly of the manifold itself, and does not relate to the assembly of the guide cone, as is the case in the present invention.

[0012] Finally, document WO2001025083A1 is also part of the general state of the art and covers a method for positioning subaqueous articles and provides a solution for aligning equipment that is lowered from the ocean surface. The invention provides for the use of a thrust assembly including two thrust units mounted on opposite ends of a metal pipe which is suspended in water by lifting rigging. It should be noted that the aforementioned document is more related to a subsea alignment system operated with hydraulic thrusts for large-scale subsea movements, unlike the present invention which aims at mounting the guide cone of the manifold HUB.

[0013] It is also important to highlight that the present invention offers advantages considering the economic and productivity impact, which is associated with the fact that it enables the use of a manifold HUB that had become inoperative due to the impossibility of performing a new DVC (Direct Vertical Connection) operation.BRIEF DESCRIPTION OF THE INVENTION

[0014] The present invention refers to subsea maintenance, more specifically the decommissioning of flexible pipelines and the assembly of subsea equipment, and refers to a system and method for the subsea assembly of a guide cone on a manifold HUB. The present invention finds use in instances where it is necessary to reassemble guide cones in manifolds that are already installed on the seabed, allowing for the use of a manifold HUB that had become inoperative due to the impossibility of performing a new DVC (Direct Vertical Connection) operation.BRIEF DESCRIPTION OF THE FIGURES

[0015] To provide a comprehensive and full view of the goal of the present invention, the figures are presented below, which are referred to as follows.

[0016] FIG. 1 schematically depicts the split ring, according to a preferred embodiment of the present invention.

[0017] FIG. 2 shows schematically the split plate with special nuts placed to guide the screws, according to a preferred embodiment of the present invention.

[0018] FIG. 3 schematically represents the mechanism for positioning the guide cone in the HUB, according to a preferred embodiment of the present invention.

[0019] FIG. 4 (4a, 4b and 4c) schematically represents the ROV support table located near the HUB in different views, according to a preferred embodiment of the present invention.

[0020] FIG. 5 schematically represents the ROV mounting the guide cone on the HUB, according to a preferred embodiment of the present invention.

[0021] FIG. 6 shows the mechanism for placing the guide cone in the HUB, highlighting the regions where screws should not be mounted.

[0022] FIG. 7 shows the mechanism for placing the guide cone in the HUB, highlighting the tie rods that hold the tabs of the split ring.

[0023] FIG. 8 shows the HUB capped with a protective cap.

[0024] FIG. 9 shows the mechanism for positioning the guide cone in the HUB, highlighting the release of the shackles.

[0025] FIG. 10 shows the procedure for installing hex socket screws (Allen).

[0026] FIG. 11 shows the torque sequence for the screws.DETAILED DESCRIPTION OF THE INVENTION

[0027] The present invention relates to a system and method for underwater mounting a guide cone on a manifold HUB. The system comprises a split ring, a split plate, a mechanism for positioning the guide cone on the HUB, and a support table for the ROV, which is located near the Manifold HUB.

[0028] The split plate holds the split ring, the mechanism for positioning the guide cone on the HUB centers the guide cone for subsequent attachment of the split ring. The ROV support table is used for docking the ROV.

[0029] As shown in FIG. 1, the split ring comprises two main parts, each part comprising at least four special nuts equally spaced at an angle of preferably 45°. Positioning of the nuts is important as they serve as a guide for placing the split ring (this component locks the guide cone to the HUB groove).

[0030] The nuts can be 1″ hexagonal and can be made of steel. As shown in FIG. 2, the split plate of the mounting device includes recesses to assist in the correct placement of the split ring and subsequent connection of the special nuts.

[0031] The split plate comprises two shafts at the ends, which are directed outwards from the plate and serve to fit the wrench and can be manufactured from SAE 1045 steel. The split plate further includes support elements (shown in green) to assist in securing the guide cone (“panelão”), at least four padeyes (elements shown in green with a central opening and at least four guide cone bracing elements (elements shown in blue).

[0032] The split plate further includes four openings at opposite ends for attaching bottom screws, which may be 1″×138 hex socket c-c screws (Allen). The positioning mechanism on the HUB comprises a guide cone (“panelão”), as shown in FIG. 3, a master link ring to which the vessel winch is connected, and a four-leg sling to assist in maneuvering the assembly.

[0033] The guide cone comprises four T-shaped elements arranged in its interior and has openings at its bottom having the same configuration as the split ring, thereby allowing them to be bolted together. The support table for the ROV, as shown in FIG. 4a, can be 2 meters high and include central openings.

[0034] In general, the method of subsea mounting of a guide cone on a manifold HUB comprises the following steps:

[0035] (a) installing the Teflon cover on the HUB, wherein a RSV vessel (ROV Support Vessel) installs it in the subsea environment via ROV at the manifold hub,

[0036] (b) coupling the Guide Cone on the HUB and disconnecting the sling and buoys, wherein the RSV vessel is connected to its crane cable with the four-leg sling and masterlink ring,

[0037] (c) tightening the Guide Cone Centering Screws with the Split Ring, where the ROV places the guide cone centering mechanism on the HUB, tightening the first and second stroke screws of the split ring,

[0038] (d) aligning the Guide Cone Openings and the Split Ring, wherein the alignment of the split ring with the guide cone is permitted from two spindles installed on the base of the mechanism,

[0039] (e) placing screws and applying torque, wherein the screws inside the guide cone (“panelão”) are positioned in the openings using a magnetic tool and subsequently torqued with a hydraulic torque wrench attached to a handle designed for each position,

[0040] (f) removal of the system, where the entire system used for mounting and centering the guide cone and HUB is removed, and

[0041] (g) removal of the Teflon cover, at which point the HUB is ready for a new DVC. Detail of the special nuts mounted on the split ring.

[0042] Due to difficulty of access, the torques applied were from (244N.m initial) to (519 N.m final), according to the torque procedure.

[0043] More specifically, the method first comprises a step of “preparing the tools required for performing the activities” (step 1), in which buoyancy devices are installed on all equipment and tools that are handled by the ROV, where necessary (e.g., a nylon rope monkey fist with a minimum length of 400 mm, to assist in the retrieval of such equipment in the event that it becomes detached and falls onto the seabed). Preparation of the hub protection device is also carried out in the ROV tool tray. If required, the device is lowered in the tool basket via the vessel crane.

[0044] Thereafter, the step of “placing the guide cone on the installation device for lowering together with its deployment sling” is carried out (step 2). A transfer strap or sling is provided on the masterlink ring of the device deployment sling, as it will be used to transfer the buoyancy force from the buoy to the dead weight at a later stage.

[0045] Length of the strap to be used must be verified on-site during the survey stages (inspection). Due to the equipment weighing over 100 kg in the water, the onboard crew should assess the need to install the accessory using flotation devices to neutralize its weight. If necessary, a lifting strop should be attached to the upper end of the equipment for installing the buoy so that it is lowered at the proper installation position.

[0046] Attention should be paid to the following points during preparation of the device prior to deployment to the working depth: 1) Refrain from assembling the screws at the positions indicated in FIG. 6, as this side will be on the back of the HUB; 2) The parts indicated in FIG. 1 act as stoppers, aligning the openings of the guide cone with the nuts of the split ring, where they will be bolted to secure the HUB; 3) Attention should be paid to the correct placement of the nuts, as they will serve as a guide for positioning the split ring, as shown in FIG. 2; 5) Attention should be paid to the tie rods securing the tabs of the split ring, as shown in FIG. 7; 6) Attention should be paid to the upper centering screws that should be lowered while mounted on the guide cone, as shown in FIG. 3.

[0047] The next step is to “Surveying (inspecting) and locating the points of interest according to the coordinates” (step 3). During the survey, the vessel must assess whether there is any interference near the operation site. If any obstruction is identified that could hinder or prevent the operation, the crew must assess it and record it in a report. If necessary, the survey may be extended to other locations to ensure safety and the proper execution of the operation.

[0048] Next, the step of “Assessing a clear area on the seabed near the operation site for positioning the concrete mooring anchor and dead weight” is carried out (step 4). Thereafter, the step of “performing metrology on the MSIAG to confirm the height of the equipment HUB relative to the seabed” (step 5) is performed. This information is important so that the table can be adjusted to the optimal height for the vehicle to operate. Metrology can be performed using a graduated ruler or other resource available on board the vessel.

[0049] In step 6, the “preparation and lowering of the ROV table, and its positioning near MSIAG-FC-014 such that the vehicle can operate at the equipment HUB,” is carried out. The table should be lowered at the proper height required for operation with the ROV. In step 7, using the vessel winch or crane, a concrete mooring anchor is lowered and placed on the seabed near the operation site.

[0050] In step 8, using the vessel winch or crane, the device is deployed together with the guide cone and placed on the concrete mooring anchor. After the placement of the device, the crane cable is released. Due to the equipment weighing over 100 kg in the water, the onboard crew should assess the need to install the accessory using flotation devices to neutralize its weight.

[0051] If necessary, a lifting strop should be attached to the upper end of the equipment for installing the buoy so that it is lowered at the proper installation position. The use of 600 kg of buoyancy force is suggested; however, the vessel crew may determine the required amount. If the onboard crew deems it more appropriate to deploy the equipment without the buoy and to transfer the required buoyancy force at the sea bottom, this may also be performed. There is also the need to assess the use of the vessel heave when positioning the equipment over the mooring anchor and the HUB.

[0052] In step 9, with the ROV at the working depth resting on the table, the mouth of the HUB should be capped with the protective cap available on board, as shown in FIG. 8. After positioning the protective cap on the HUB, the ROV should pick up the installation device along with the guide cone and move towards the table.

[0053] With the ROV properly supported on the table and aligned, the installation device should be fit onto the equipment HUB. If the equipment is being positioned using the vessel's crane, the heave compensator must be engaged at all times. After positioning, crane cable should be released.

[0054] After positioning the guide cone over the HUB, the dead weight should be deployed and placed on the seabed near the operation site. Next, the float buoyancy is transferred to the deadweight slowly and gradually, so as not to damage the equipment. A strap or sling may be used with the transfer attachment. Once the transfer strap or sling is properly attached to the dead weight, the 12.5-ton shackles should be released, and the tie rods securing the tabs of the split ring should be cut and removed.

[0055] Accordingly, as soon as the shackles are gradually released, the buoyance force will be transferred to the dead weight, as shown in FIG. 9. After removing the buoy along with the guide cone deployment sling, they should be retrieved to the deck.

[0056] After completing the previous steps, using the wrench, the tabs of the split ring must be brought together, attaching the guide cone to the HUB. They shall be bolted by aligning the holes of the ring and the guide cone. A 1 ⅝″ hexagonal wrench is used, as shown in FIG. 5.

[0057] Next, the step of “checking or inspecting whether the openings in the guide cone are at the same position as the split ring” should be carried out. After confirming that the accessory openings are correctly drilled, the 1″ Hex socket screws should be installed to secure the guide cone, as shown in FIG. 10. A wrench with a ¾″ magnetized Allen key adapter and a 1″ Hex socket screw should be used.

[0058] After completing the installation of all Hex socket screws, they should be torqued using the RSL-2 Hex Link 1 ⅝″ torque wrench with a ¾″ Hex socket key adapter, as shown in FIG. 11. First stage of torque application on studs 2 and 3:244 Nm (1400 psi on RSL-2). 2nd Torque Phase on studs 1 and 4:519 Nm (2800 psi on RSL-2). 3rd Torque Phase on studs 7 and 6:244 Nm (1400 psi on RSL-2). 4th Torque Phase on studs 8 and 5:519 Nm (2800 psi on RSL-2). 5th Torque Phase in all studs (from 1 to 8) sequentially with 519 Nm (2800 psi on RSL-2).

[0059] After completing the torque procedure, the two centering screws must be removed and stored in the ROV tray or tool basket.

[0060] Based on the previous disclosure, it is evident that the methodology created makes it possible to install the split cone using a completely diverless underwater operation. This new methodology enabled the maintenance and recovery of a manifold HUB that was previously inoperative, allowing connection of the platform export gas pipeline and resulting in significant financial gains.

[0061] The present invention takes advantage of the access constraints to the subsea structure and a scenario modeling, which allowed the design of special tools to reach the points of interest. In addition, a removable assembly system was developed to enable the precise installation of the guide cone at the specified location. To enable fastening without using welds, a special nut was created that allowed the guide cone to be centered with the split ring.

[0062] The present invention deals with the proper application of commercially available instruments and tools that have been assertively selected, as well as the knowledge of subsea assembly processes carried out by specialized vessels. Thus, a method was created with predefined steps that must necessarily be carried out in order for the assembly requirements to be met.

[0063] Those skilled in the art will value the knowledge presented herein and may reproduce the invention in the disclosed embodiments and other variants thereof, as covered by the scope of the appended claims.

Examples

Embodiment Construction

[0027]The present invention relates to a system and method for underwater mounting a guide cone on a manifold HUB. The system comprises a split ring, a split plate, a mechanism for positioning the guide cone on the HUB, and a support table for the ROV, which is located near the Manifold HUB.

[0028]The split plate holds the split ring, the mechanism for positioning the guide cone on the HUB centers the guide cone for subsequent attachment of the split ring. The ROV support table is used for docking the ROV.

[0029]As shown in FIG. 1, the split ring comprises two main parts, each part comprising at least four special nuts equally spaced at an angle of preferably 45°. Positioning of the nuts is important as they serve as a guide for placing the split ring (this component locks the guide cone to the HUB groove).

[0030]The nuts can be 1″ hexagonal and can be made of steel. As shown in FIG. 2, the split plate of the mounting device includes recesses to assist in the correct placement of the s...

Claims

1. A system for subsea assembly of a guide cone on a manifold HUB, comprising:a guide for a split ring;a split plate;a mechanism for positioning the guide cone on the HUB; anda support table for the ROV, located near the Manifold HUB.

2. The system according to claim 1, wherein:the split plate holds the split ring,the mechanism for positioning the guide cone on the HUB centers the guide cone for subsequent attachment of the split ring, andthe ROV support table serves for docking the ROV.

3. The system according to claim 1, wherein the split ring comprises two main parts, each part comprising at least four special nuts equally spaced at an angle of preferably 45°.

4. The system according to claim 1, wherein the positioning of the nuts serves as a guide for positioning the split ring.

5. The system according to claim 1, wherein the split plate comprises recesses to aid in positioning the split ring and subsequently connecting the special nuts.

6. The system according to claim 1, wherein the split plate comprises:two shafts at the ends, being directed outwards from the plate and used for attaching the wrench,support elements to assist in securing the guide cone, at least four padeyes, and at least four brace elements for the guide cone, andopenings at opposite ends for attaching bottom screws.

7. The system according to claim 1, wherein the mechanism for positioning the guide cone on the HUB comprises: a guide cone, a master link ring connected to the vessel's winch, and a four-legged sling to assist in the maneuver of the assembly.

8. The system according to claim 1, wherein the guide cone comprises four T-shaped elements in its interior as well as openings at its base with the same configuration as the split ring, enabling them to be bolt together.

9. A method for subsea assembly of a guide cone on a manifold HUB, the method comprising the steps of:installing the Teflon cover on the HUB;coupling the guide cone to the HUB and disconnecting the sling and buoys;tightening the Centering Screws of the Split Cone;aligning the openings of the Guide Cone and the Split Ring;placing the screws and applying torque;removing the system; andremoving the Teflon cover.

10. The method according to claim 9, wherein the Teflon cover is installed in the underwater environment via ROV.

11. The method according to claim 10, wherein in step c the ROV places the device by tightening the first and second stroke screws of the split ring.

12. The method according to claim 9, wherein the alignment of the split ring with the guide cone is made via two spindles installed at the base of the mechanism.

13. The method according to claim 9, wherein the screws inside the guide cone are positioned in the holes using a magnetic tool and subsequently torqued with a hydraulic torque wrench attached to a handle designed for each position.

14. The method according to claim 9, wherein the applied torques are preferably from an initial torque of 244 N.m to a final torque of 519 N.m.

15. The method of claim 9, wherein the method promotes maintenance and recovery of a manifold HUB that was inoperative.

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