MOORING EQUIPMENT FOR USE IN IN-LINE TENSIONING

Abstract

Systems and methods for tensioning mooring lines are provided. The systems include an in-line tensioner that may include a removable chainwheel, a tail chain disconnecting table configured for disconnection of a tail chain and docking of an ROV, a chain guide having low-friction pads that reduce frictional engagement between the in-line tensioner and mooring chains, and a target link stopper that is configured to stop movement of the mooring line at a predetermined location, such that the mooring line has a predetermined length and such that a predetermined link of the mooring line is positioned within a gripping zone of latches of the in-line tensioner.

Description

FIELD

The present disclosure relates to systems and methods for mooring vessels and tensioning mooring lines. In particular, the present disclosure relates to systems and methods that use an in-line tensioner to tension mooring lines.

BACKGROUND

In many applications, floating vessels require mooring, such as in offshore drilling platform applications. The mooring lines typically require at least some tensioning to securely moor the vessel. One approach to mooring and tensioning includes the use of a so called “in-line tensioner” (“ILT”) to tighten mooring lines.

BRIEF SUMMARY

Some embodiments of the present disclosure include an in-line tensioner for tensioning mooring lines.

In some embodiments, the in-line tensioner includes a frame configured to couple with a bottom chain of mooring line, latches coupled with the frame and positioned to grip a top chain of mooring line, and a chainwheel. The chainwheel has at least two configurations. The at least two configurations include a first configuration with the chainwheel coupled with the frame and positioned to guide a top chain of mooring line, and a second configuration with the chainwheel decoupled from the frame.

In some embodiments, the in-line tensioner includes a frame configured to couple with a bottom chain of mooring line, latches coupled with the frame and positioned to grip a top chain of mooring line, a chainwheel coupled with the frame and positioned to guide a top chain of mooring line, and a chain guide coupled with the frame and positioned to guide a top chain of mooring line. The latches are positioned between the chainwheel and the chain guide. Pads are on the chain guide and positioned to slidingly engage with a top chain of mooring line as the mooring line passes through the in-line tensioner. The chain guide includes a first material and the pads include a second material. The first material and the second material are different materials. The second material exhibits a lower coefficient of friction relative to a top chain sliding along the second material than a coefficient of friction exhibited by the first material relative to a top chain sliding along the first material.

In some embodiments, the in-line tensioner includes a frame configured to couple with a bottom chain of mooring line, latches coupled with the frame and positioned to grip a top chain of mooring line, a chainwheel coupled with the frame and positioned to guide a top chain of mooring line, and a tail chain disconnecting table integral with or coupled to the frame. The tail chain disconnecting table is configured to receive and secure a tail chain of mooring line.

Some embodiments of the present disclosure include a mooring system that includes a mooring line having a bottom chain and a top chain. The system includes an in-line tensioner having a frame and latches coupled with the frame. The bottom chain is coupled with the frame. The latches are positioned to selectively grip the top chain such that a length of the top chain portion of the mooring line is adjustable. The system includes a target link stopper coupled with the top chain. The target link stopper is positioned along the top chain such that when the target link stopper engages the in-line tensioner the mooring line has a target length.

Some embodiments of the present disclosure include a method of mooring a floating vessel.

In some embodiments, the method includes providing an in-line tensioner having a frame, a chainwheel coupled with the frame, and latches coupled with the frame. The method includes providing a mooring line including a bottom chain and a top chain, coupling the bottom chain between the frame and an anchor, and coupling the top chain with the chainwheel. The method includes coupling a first end of the top chain with the floating vessel. The method includes adjusting a length of the top chain between the floating vessel and the in-line tensioner until the mooring line has a target length. The chainwheel guides movement of the top chain during the adjusting. The method includes gripping the top chain with the latches when the mooring line has the target length. The method includes removing the chainwheel from the in-line tensioner while the mooring line has the target length.

In some embodiments, the method includes providing an in-line tensioner having a frame, a chainwheel coupled with the frame, latches coupled with the frame, and a chain guide couple with the frame. The chain guide has pads positioned thereon. The method includes providing a mooring line including a bottom chain and a top chain, coupling the bottom chain between the frame and an anchor, and coupling the top chain with the chainwheel. The method includes coupling a first end of the top chain with the floating vessel. The method includes adjusting a length of the top chain between the floating vessel and the in-line tensioner until the mooring line has a target length. The chainwheel guides movement of the top chain during the adjusting. The method includes gripping the top chain with the latches when the mooring line has the target length. The latches are positioned along the top chain between the chainwheel and the chain guide. During the adjusting of the length of the top chain, the top chain slides along the pads. The chain guide includes a first material and the pads include a second material. The first material and the second material are different. The second material exhibits a lower coefficient of friction relative to the top chain sliding along the second material than a coefficient of friction exhibited by the first material.

In some embodiments, the method includes providing an in-line tensioner having a frame, a chainwheel coupled with the frame, latches coupled with the frame, and a tail chain disconnecting table integral with or coupled to the frame. The method includes providing a mooring line including a bottom chain and a top chain, coupling the bottom chain between the frame and an anchor, and coupling the top chain with the chainwheel. The method includes coupling a first end of the top chain with the floating vessel. The method includes adjusting a length of the top chain between the floating vessel and the in-line tensioner until the mooring line has a target length. The chainwheel guides movement of the top chain during the adjusting. The method includes gripping the top chain with the latches when the mooring line has the target length. The method includes securing a tail chain of the top chain to the tail chain disconnecting table, and removing at least some of the tail chain from the top chain.

In some embodiments, the method includes providing an in-line tensioner including a frame, a chainwheel coupled with the frame, and latches coupled with the frame. The method includes providing a mooring line including a bottom chain and a top chain, coupling the bottom chain between the frame and an anchor, and coupling the top chain with the chainwheel. The method includes coupling a first end of the top chain with the floating vessel. The method includes coupling a target link stopper with the top chain. The target link stopper is positioned along the top chain such that when the target link stopper engages the in-line tensioner the mooring line has a target length. The method includes adjusting a length of the top chain between the floating vessel and the in-line tensioner until the target link stopper engages the in-line tensioner. The method includes gripping the top chain with the latches when the target link stopper is engaged with the in-line tensioner.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the features and advantages of the system, apparatus, products, and/or methods so of the present disclosure may be understood in more detail, a more particular description briefly summarized above may be had by reference to the embodiments thereof which are illustrated in the appended drawings that form a part of this specification. It is to be noted, however, that the drawings illustrate only various exemplary embodiments and are therefore not to be considered limiting of the disclosed concepts as it may include other effective embodiments as well.

FIG. 1 depicts a mooring set up.

FIG. 2A depicts another mooring set up.

FIG. 2B depicts a detail view of the mooring set up of FIG. 2A.

FIG. 3 is a perspective view of an in-line tensioner.

FIG. 4 a top view of an in-line tensioner.

FIG. 5 is a side view of an in-line tensioner.

FIG. 6 is an end view of an in-line tensioner.

FIG. 7 is a perspective view an in-line tensioner with a chain engaged therewith.

FIG. 8 depicts an in-line tensioner with the chainwheel removed.

FIG. 9A is a perspective view of a target link stopper.

FIG. 9B is an end view of a target link stopper.

FIG. 9C is a side view of a target link stopper.

FIG. 9D is a cross sectional view of the target link stopper of FIG. 9B along line A-A.

FIG. 9E is another perspective view of a target link stopper.

FIG. 10A is a perspective view of a target link stopper engaged with a chain guide.

FIG. 10B is a side view of a target link stopper engaged with a chain guide.

FIG. 11 depicts an in-line tensioner having a chainwheel attached thereto.

FIG. 12A depicts a tail chain secured on a tail chain disconnecting table including a disconnecting link in a flat orientation.

FIG. 12B depicts a tail chain secured on a tail chain disconnecting table including a disconnecting link in a vertical orientation.

FIG. 12C depicts a tail chain secured on a tail chain disconnecting table including a disconnecting link in a hanging orientation.

FIG. 13A depicts an in-line tensioner with a tail chain secured to a tail chain disconnecting table.

FIG. 13B depicts the in-line tensioner of FIG. 13A, with the chainwheel being lifted from the in-line tensioner.

FIG. 14 depicts an ROV docked at the tail chain disconnecting table and removing a link therefrom.

FIG. 15 depicts an in-line tensioner coupled with a mooring line and without a chainwheel thereon.

DETAILED DESCRIPTION

Certain aspects of the present disclosure include systems and methods for mooring vessels and tensioning mooring lines. The present disclosure includes systems and methods for mooring vessels and tensioning mooring lines using or incorporating in-line tensioning technology. Embodiments of the present disclosure include an in-line tensioner that can be positioned in or along a mooring line and used to tighten the mooring line. As described in more detail below, embodiments of the in-line tensioner disclosed herein include: (1) a removable chainwheel; (2) a chain guide with low-friction pads that reduce frictional engagement with chains; (3) a target link stopper for stopping movement of mooring lines at predetermined locations; (4) a disconnecting table providing for disconnection of tail chain from mooring lines; (5) or combinations thereof.

Mooring Set Up

FIG. 1 depicts an exemplary mooring set up in which the in-line tensioner systems and methods disclosed herein may be applied. While FIG. 1 depicts moored wind turbine 12, the in-line tensioner systems and methods disclosed herein are not limited to use in mooring wind turbines, and may be used to moor other structures, such as oil and gas drilling and production platforms, ships, or other floating structures.

As shown, mooring set up 10 includes wind turbine 12 is moored to seabed 14 via mooring line 16. Mooring line 16 includes chain 18 (bottom chain) anchored to seabed 14. Chain 18 is coupled with in-line tensioner 20. Mooring line 16 includes wire 22 (top chain), which is coupled with in-line tensioner 20 opposite chain 18. Mooring line 16 includes H-links 24 coupled with wire 22, and tri-plate 28 coupled with H-links 24 via chain 26. Chain, rope or wire 30 (e.g., minimum breaking load chain) is coupled between tri-plate 28 and replaceable strongpoints 32 of wind turbine 12.

FIGS. 2A and 2B depict another mooring set up, demonstrating the use of an anchor handling vessel in the tensioning of a mooring line. Mooring set up 34 includes mooring line 42 positioned to moor wind turbine 48. Mooring line 42 includes anchor chain 44 (bottom chain) coupled with chain 46 (top chain) via in-line tensioner 40. Anchor handling vessel 36 is positioned to pull on wire or chain 38, which is coupled with in-line tensioner 40 and is coupled with or integral with chain 46. Pulling on wire or chain 38 results in the tensioning of chain 46; thereby, tensioning of mooring line 42.

The mooring set ups shown in FIGS. 1-2B are examples of mooring set ups in which the systems and methods disclosed herein may be used for mooring operations. One skilled in the art would understand that the in-line tensioner systems and methods disclosed herein may be used in other mooring set ups and arrangements.

In-Line Tensioner

Certain embodiments of the present disclosure include an in-line tensioner. With reference to FIGS. 3-8, an in-line tensioner in accordance with at least some embodiments of the present disclosure is depicted. In-line tensioner 101 (also referred to as ILT 101) is configured to receive coupled with a mooring line, and to lock a position of the mooring line to provide the mooring line with a desired tension and length. In-line tensioner 101 includes frame 103. Frame 103 provides a latch housing for latches of the in-line tensioner 101 and provides a mount for mounting a chainwheel of the in-line tensioner 101. Frame 103 may be the primary body of the in-line tensioner 101.

Frame 103 is mounted on mud mat 107 (e.g., a skid). Mud mat 107 provides the in-line tensioner 101 with the ability to be moved around a deck of an anchor handling vessel (AHV), such as by tugger winches, and provides a structure to withstand loads induced when deploying the in-line tensioner 101 over a stern roller of the anchor handling vessel under tension, which can be up to 1000 kN. The mud mat 107 also provides a surface of the ILT 101 that can be placed on the seafloor. For example, the mud mat 107 can be placed on the seafloor when attached with a mooring line that is pre-laid, or the mud mat 107 can be placed on the seafloor while the mooring line is being replaced.

ILT 101 is coupled with chain 135 (also referred to as anchor chain or bottom chain). For example, chain 135 can be fixedly coupled with frame 103 of ILT 101, such as via chain connector 141. Chain connector 141 is coupled (e.g., pinned to via a pin connection) with chain 135 and with frame 103 (at 103a) via bushings 143. The bushings 143 may be composite bushings to provide galvanic isolation. The bushings 143 may include a material that is capable of withstanding full mooring load design (MBL of the mooring line). In some embodiments, the bushings 143 include a low-friction bearing material. In some embodiments, chain 135 is a “passive chain connection,” such that a length of chain 135 is not adjustable (i.e., is passive). That is, with the chain 135 attached at one end to an anchor and at the other end to the ILT 101, the length of the chain 135 between the anchor and the ILT 101 is static (does not change).

ILT 101 is coupled with chain 131 (also referred to as top chain or work chain). The connection between ILT 101 and chain 131 is an “active chain connection,” such that a length of chain 131 is adjustable. That is, using an AHV in conjunction with the chainwheel and latches of the ILT 101, the length and tension of chain 131 is adjustable, providing for mooring of structures that are coupled with chain. For example, an AHV can haul in or pay out chain 131 to increase or decrease the tension on chain 131.

As shown in FIG. 7, the passive chain connection is located at a bottom end of ILT 101, and the active chain connection is located at a top end of the ILT 101, with the chainwheel 115 positioned between the passive chain connection and the active chain connection. In some embodiments, the passive chain connection includes an ROV operable pin connection (not shown) for disconnecting the frame 103 from chain 135. Tension on the mooring line can be removed to allow an ROV operable pin connection to be safely and reliably released when desired.

Removable Chainwheel

ILT 101 includes removable chainwheel 115. While the embodiment of chainwheel 115 shown in FIGS. 3-7 is a dual chainwheel, the systems and methods disclosed herein are not limited to use with dual chainwheels. Chainwheel 115 is mounted (e.g., pinned) on frame 103 at locations 103b. In particular, chainwheel 115 includes chainwheel mounting frame 153, which is pinned with frame 103. Chainwheel 115 is rotatably mounted onto chainwheel mounting frame 153 via chainwheel axle 152, such that chainwheel 115 can rotate relative to chainwheel mounting frame 153.

The frame 103 can include a chainwheel dock configured to receive and secure the chainwheel 115, such as funnels 159 and pins 157. Chainwheel mounting frame 153 includes stabbing pins 161. Stabbing pins 161 are configured to engage within mating funnels 159 of frame 103. Thus, stabbing pins 161 and mating funnels 159 provide for engagement and disengagement between chainwheel mounting frame 153 and frame 103. In some embodiments, the chainwheel mounting frame 153 includes counterweights to facilitate the stabbing pins 161 remaining in the desired orientation (e.g., vertical) as the chainwheel 115 is lowered into place onto the frame 103 during installation of the chainwheel 115 onto the ILT 101. The chainwheel mounting frame 153 is pinned to the frame 103 via pins 157. The chainwheel and chainwheel frame is not limited to the particular structure shown here, and may have other structures capable of being selectively attached and detached from the ILT to provide a removable chainwheel. Thus, the removable chainwheel 115 disclosed herein has at least two configurations. The at least two configurations include a first configuration with the chainwheel 115 is coupled with the frame 103 and positioned to guide top chain 131, and a second configuration with the chainwheel 115 is decoupled from the frame 103 and removed from the ILT 101.

In operation, the chainwheel 115 rotates, guiding the chain 131 as the chain 131 is hauled-in or paid-out (e.g., hauled in or paid out via an AHV). In some embodiments, the chainwheel 115 has one or more (e.g., two) wildcat profiles that have surface contours designed to engage with the chain, and includes chain contact areas shaped to follow (mate with) the shape of the chain links; thereby, minimizing local stresses. In some embodiments, the chainwheel 115 is a dual chainwheel capable of engaging with and guiding at least two different sized chains. In other embodiments, the chainwheel 115 is a single chainwheel designed for use with just one chain size. In embodiments where the chainwheel 115 is a dual chainwheel, the dual chainwheel is configured to provide for a seamless transition from engagement with a smaller adjustment chain to engagement with a mooring chain. For example, a connector (link coupler) can connect the two different sized chains and engage with the dual chainwheel to facilitate the transition between the chain sizes. For example, and without limitation, the chainwheel 115 may be the same as or similar to the chainwheel disclosed in U.S. Patent Publication No. 2019/0092599 (the '599 Publication), the entirety of which is incorporated herein by reference. Also, the link coupler disclosed in the '599 Publication may both be used to connect the smaller adjustment chain with the larger mooring chain. Use of the link coupler and dual chainwheel can ensure that the two different chain sizes stay “clocked” on the chai wheel 115 and fall into the appropriate pockets of the chainwheel 115 for chain support; thereby, at least reducing bending on the chain links.

In some embodiments, the chainwheel 115 includes two self-lubricating bushings that minimize rotating resistance relative to the mounting frame 153, without requiring the use of external grease lubrication.

Handle 173 is coupled with chainwheel mounting frame 153. In operation, handle 173 may be used to manipulate (e.g., move) chainwheel 115 and chainwheel mounting frame 153, such as for installation onto frame 103 and for removal from frame 103. For example, a wire, rope or chain of a winch or crane (e.g., on an AHV) may engage with handle 173 to lift chainwheel 115 and chainwheel mounting frame 153 from frame 103 or to lower chainwheel 115 and chainwheel mounting frame 153 onto frame 103. The ability to easily remove and reattach chainwheel 115 allows for removable of chainwheel 115 to reduce weight of the ILT 101 when the chainwheel 115 is not in use, and allows for the reattachment of the chainwheel 115 for operations, such as to haul-in or pay-out chain. Reducing the weight of the ILT 101 provides for better long-term performance of the ILT 101; reduces the number of moving parts left in the water column, reducing concerns over marine growth and corrosion; shifts the center of gravity of the ILT 101 to a position below the chain line of action so that there is reduced occurrence of twisting of the mooring line after tensioning; provides for better maintainability of moving parts (e.g., chainwheel bearings); or combinations thereof. As used herein, the “chain line” is an imaginary line that is coincident with the extension of the mooring line. Thus, with the center of gravity of the ILT 101 below the chain line, the center of gravity of the ILT 101 is closer to the seabed than the chain line.

The removability of chainwheel 115 also allows the chainwheel 115 to be used and re-used with multiple different in-line tensioners, reducing the total number of chainwheels 115 needed for mooring operations and, thus, reducing the overall cost of mooring operations. The funnels 159 and pins 161 provide for the easy docking of the chainwheel 115 onto the frame 103, as aligning the pins 161 with the funnels 159 and inserting the pin 161 into the funnels ensures that the chainwheel 115 is docked at the correction location and in the correct orientation. Additionally, the pins 157 that secure the docked chainwheel 115 to the frame 103 can be ROV operable, providing easy securement of the chainwheel 115 to the frame 103. The reverse operation of the pins 157, pins 161, and funnels 159 provide for ease of removal of the chainwheel 115 from the frame.

Chain Guide with Low-Friction Pads

ILT 101 includes chain guide 117. Chain guide 117 is positioned and configured to guide chain 131 into ILT 101 towards the latches thereof. Chain guide 117 may be a tapered funnel that guides chain. Guide 117 may be useful if, for example, the chain is laterally misaligned from the ILT 101 and simultaneously rotated (e.g., up to approximately 20 degrees). Chain guide 117 and frame 103 are equipped with anodes 119, which provide for cathodic protection. Chain guide 117 (chain guide shoe) is positioned at the outboard end of frame 103. In the embodiment shown, chain guide 117 is a double “V” shaped funnel that contacts the chain links to assist in leading the chain properly into the chainwheel 115 and latches 145 during the hauling-in of the chain. However, the chain guide disclosed herein is not limited to this particular embodiment.

Chain guide 117 includes low-friction pads 118 thereon. Low-friction pads 118 are positioned to engage with chain 131 passing through chain guide 117. Low-friction pads 118 exhibit reduced friction when the chain 131 slides along a surface of the low-friction pads 118 during hauling in or paying out in comparison to the degree of friction that would be exhibited by the chain 131 sliding along a surface of the underlying chain guide 117 (without the low-friction pads 118 thereon). For example, the low-friction pads 118 can include a material that is different than the material of the underlying chain guide 117. In some embodiments, the low-friction pads 118 include a material that is different than the material of the chain 131. The material of the low-friction pads 118 can be a material that exhibits a lower coefficient of friction with the mooring chain 131 as the chain 131 slides along the low-friction pads 118, in comparison to the coefficient of friction that would be exhibited by the material of the underlying chain guide 117 if the mooring chain 131 were sliding along the material of the underlying chain guide 117. In some embodiments, the chain guide 117 and the mooring chain 131 both include the same material, such as steel. Without being bound by theory, a steel mooring chain sliding along plate steel of a chain guide, in seawater, typically exhibits a CoF of from 0.25 to 0.5. Thus, the CoF of a steel mooring chain sliding along the low-friction pads 118, in seawater, may be less than 0.5, or less than 0.25, or less than 0.2. By reducing the friction of engagement between chain 131 and chain guide 117, low-friction pads 118 reduce tendency for the ILT 101 and chain catenary to repeatedly rise and fall as the chain 131 is hauled up from an AHV. That is, the low-friction pads 118 reduce friction during tensioning of the mooring line and, thus, reduce the tendency to repeatedly lift and drop the ILT 101 due to static friction of the chain rubbing on the chain guide 117. The reduction in friction provided by low-friction pads 118 at the chain guide 117 interface with chain 131 facilitates better control of the mooring operation in comparison with an otherwise identical ILT without the low-friction pads 118.

Latches

Chain guide 117 guides chain 131 to latches 145 of ILT 101. Latches 145 are, or from a part of, a chain stopper of ILT 101. Latches 145 are coupled with frame 103 and positioned to engage with chain 131 passing through ILT 101. Latches 145 are operable to open, such that the latches 145 are clear of the chain links passing through ILT 101. Latches 145 are also operable to close, such that the latches 145 engage with (latch upon) the chain links passing through ILT 101. In some embodiments, latches 145 are rotatable to change the orientation of the latches 145 relative to the extension of the chain, such that the latches 145 can rotate to engage both vertical links and flat links. As used herein, “flat links” and “vertical links” refer to adjacent links on a chain that are oriented 90 degrees or substantially 90 degrees from one another, as would be well understood by one of ordinary skill in the art. For example, U.S. Pat. No. 10,272,973 (the '973 Patent) discloses a rotatable chain stopper capable of rotating latches to engage both flat and vertical links. In some embodiments, the latches disclosed herein are the same as or similar to the rotatable latches disclosed in the '973 Patent, the entirety of which is incorporated herein by reference. In some embodiments, the latches 145 include latch pawls that contain machined contoured pockets configured and shaped to cradle the chain links, thus, maximizing the chain contact surface and reducing chain wear. In some embodiments, the latches 145 are rotatable latches that permit various orientations of the chain; thereby, reducing off center forces on the latches 145 and the chain. In some embodiments, the latches 145 include a material that has a lower hardness than the material of the chain to ensure that the chain sets into the latches 145 and that local yielding that may occur will be on the latches 145 and not the chain.

The latches 145 can be mechanically opened by the chain as the chain is hauled-in. The embodiment shown includes two latches 145 that are mechanically linked to synchronize their movement via synchronizing linkage 127. The closing force of the latches 145 may be provided by mechanical springs 125 (latch closing spring) that are coupled therewith and bias the latches 145 closed. Alternative methods for providing the closing force of the latches 145 include use of a counterweight, pneumatic or hydraulic springs, or a combination of these methods depending on the particular application. In some embodiments, an ROV can be used for remote operation of the latches 145, a diver can operate the latches 145, or a mechanical wire routed to an AHV above can operate the latches 145. For example, the latches 145 can be pinned in the open position (clear of the chain) by an ROV or diver during chain pay-out of the chain, if desired.

ILT 101 includes latch lock 121 for locking a position of latches 145, and latch open handle 123 for opening latches 145. In one exemplary embodiment, to pin the latches 145 in the open position, an ROV is operated to twist latch lock pin 121; thereby, actuating the lock open mechanism. When the latches 145 are opened, the latches 145 can automatically lock in the open position. Latches 145 can be opened by an ROV after chain tension has been removed or by hauling the chain in a short distance (e.g., less than one chain pitch, or about one and a half chain links) until a first link contacts the bottom of the latches 145 and pushes the latches 145 into the open position, at which point the lock open mechanism maintains the latches 145 open for chain pay-out. When chain pay-out is complete, an ROV can be operated to pull on the latch lock 121 handle to disengage the latch lock 121, and the latches 145 will close, automatically. In some embodiments of the in-line tensioner 101, remote operation of the latches 145 can be controlled by a hydraulic cylinder mounted to the frame 103 and controlled by hoses and/or piping that is routed to a deck above or controlled by acoustic and/or radio remote (e.g., a deck of an AHV).

In some embodiments, latches 145 are designed to stop a mooring chain in a manner that reduces chain stress by supporting the chain on two contoured latches. The in-line tensioner 101 disclosed herein has a hold capacity that is equal to the mooring line minimum breaking load (MBL).

Chain Disconnecting Table

ILT 101 includes tail chain disconnecting table 109. Tail chain disconnecting table 109 is a structure configured to receive and secure the tail chain of chain 131 and provide structure for the disconnection or cutting of the tail chain portion of the chain 131. In some embodiments, tail chain disconnecting table 109 includes a docking station configured to receive and secure an ROV for use in disconnection of the chain. For example, tail chain disconnecting table 109 can include funnels or tubes 111 configured to receive docking or stabbing pins of an ROV, such that the ROV can dock onto ILT 101 for chain disconnection operations. One skilled the art would understand that the funnels or tubes can be on the ROV and stabbing pins on the tail chain disconnecting table 109. One skilled in the art would also understand that the tail chain disconnecting table can include other structures capable of receiving and securing an ROV, and is not limited to including pins and funnels.

The tail chain disconnecting table 109 can be used to disconnect tail chain from the mooring line. In some embodiments, after tensioning of the mooring line, the remaining tail chain (adjustment chain or work chain) is disconnected to reduce weight in the catenary, minimize twist in the mooring line, and eliminate complications for future reconnection due to having a long tail chain hanging in the water column. Prior to disconnecting the tail chain, the tail chain is laid onto the tail chain disconnecting table 109 of the ILT 101 and secured thereto, such as by an ROV operated pin. For example, when positioned on tail chain disconnecting table 109, chain 131 can be pinned via chain locking pin 129. Once the tail chain is pinned or otherwise secured to the tail chain disconnecting table 109, an ROV docked on the tail chain disconnecting table 109 can operate to remove at least a portion of the tail chain. Removal of at least a portion of the tail chain can include cutting a link of the tail chain, or removing a D-link (or other removable link) of the tail chain.

In some embodiments, the tail chain disconnecting table 109 is positioned outside of the chain line such that operations for removing tail chain can be performed outside of the chain line. For example, as shown in FIG. 7, tail chain disconnecting table 109 arcs upwards from the chain line (imaginary line that is coaxial with chains 131 and 135).

Target Link Stopper

Some embodiments disclosed herein include a target link stopper (TLS). With reference to FIGS. 9A-9E, one embodiment of the target link stopper 113 (TLS 113) is depicted. TLS 113 is a configured to be attached to the top, work chain of the mooring line at a predetermined location along the chain, and to stop travel of the chain at the desired length and tension during tensioning of the mooring line. For example, the TLS 113 can be positioned to stop the tensioning of the mooring line such that a predetermined chain link of the mooring line is positioned to be gripped by the latches 145 of the ILT 101. The TLS 113 can be positioned to stop the tensioning of the mooring line such that a predetermined chain link of the mooring line is positioned on the tail chain disconnecting table 109 to be cut or removed. In operation, if the ILT 101 overruns past the correct link, then it may be required to pay-out additional chain to return to the correct mooring line length. The TLS 113 can, thus, prevent or reduce overrunning of the chain.

TLS 113 includes first body end 122 coupled with (e.g., pinned to) second body end 124. TLS 113 may be included two portions pinned together. For example, body portion 133a may be pinned with body portion 133b via pin 126, and hinged via hinge 137, such that body portions 133a and 133b can opened (partially separated) by pivoting about hinge 137 and be secured about a mooring line, and then closed about the mooring line and pinned thereto via pin 126. TLS 113 has spring-loaded mechanisms, including springs 165 positioned within mated chambers 132 and 134. Each spring 165 is configured to absorb impact loads on the TLS 113, such that upon impact of TLS 113 with ILT 101, each spring 165 compresses and the second body end 124 moves toward the first body end 122. Each spring 165 is contained within matted chambers 132 and 134 of the first and second body ends 122 and 124, respectively. TLS 113 includes crush pads 167 positioned on the TLS 113 to interface engagement between the TLS 113 and ILT 101. The crush pads 167 aid in absorbing impact loading on TLS 113.

In some embodiments, the TLS 113 is ROV compatible such that the TLS 113 can be installed, removed and re-installed, before or after deployment, using an ROV.

With reference to FIGS. 10A and 10B, a spring-loaded TLS 113 is depicted engaged with chain 131 and ILT 101. TLS 113 is positioned on chain 131, prior to deployment and tensioning operations. Removal of pin 126 allows TLS 113 to be removed (e.g., using an ROV) after operations are completed. With TLS 113 attached to the desired location on chain 131, TLS 113 acts as a stop on chain 131 by engaging with ILT 101 (e.g., with chain guide 117). The chain guide 117 interfaces with the TLS 113 to accommodate and mitigate impact loading. When TLS 113 engages with ILT 101, at least some compression of TLS 113 may occur as a result of compression of the springs (springs 165) of TLS 113. Engagement of TLS 113 with ILT 101 stops further movement of chain 131, such that the desired link of the chain 131 is positioned within ILT 101 to be latched therein (by latches 145), and such that the mooring line has the desired length and/or tension. That is, TLS 113 can be positioned along chain 131 to stop movement of the chain 131 at a point when a predetermined link of the chain 131 is positioned within a gripping zone of the latches 145. The “gripping zone,” is a position where, when the latches 145 enter the closed position, a chain link positioned in the gripping zone is gripped and latched by the latches 145.

In some embodiments, the TLS 113 has a mating geometry that corresponds with the geometry of the ILT 101, such that surface contact faces of the TLS 113 and the ILT 101 are matched to spread the load over a larger surface area. In some embodiments, TLS 113 has a shape and/or size such that TLS 113 cannot pass through chain guide 117, preventing further tensioning of mooring line upon engaging of TLS 113 with chain guide 117.

One skilled in the art would understand that the target link stopper disclosed herein is not limited to the particular structure shown in FIGS. 9A-10B, and may include other structures that are capable of being coupled with a mooring line and of stopping tension of the mooring line upon engagement between the target link stopper and an in-line tensioner.

Operation

Operation of the ILT 101 in the tensioning of a mooring line will now be described. With reference to FIG. 11, ILT 101 is depicted coupled with chain 135. Chain 135 extends to an anchor (not shown) at the seabed (not shown). ILT 101 is also coupled with chain 131, including upper portion 131a and lower portion 131b. Upper portion 131a extends from ILT 101 to the structure (not shown) being moored (e.g., a wind tower). Lower portion 131b extends from ILT 101 to an anchor handling vessel (not shown). In operation, the anchor handling vessel hauls in or pays out chain 131 by reeling in or releasing chain 131. Once a desired length of chain 131 and/or tension on chain 131 is achieved, the latches of the ILT 101 are used to latch upon the chain 131 to lock the position of the chain 131 relative to the ILT 101. In some embodiments, the desired length of chain 131 and/or tension on chain 131 is determined to be present when the target link stopper engages with the ILT 101, as shown in FIGS. 10A and 10B.

While the chainwheel 115 is exposed to mooring line tension during tensioning operations, the mooring load is reacted by the latches 145. During mooring operations, the chainwheel 115 can be configured to pass an LLLC® connecting link and a messenger chain, thus, satisfying the needs of a variety of mooring, tensioning, and re-tensioning operations. The pretension loads reacted by the chainwheel 115 are, typically, relatively low in comparison with the MBL of the mooring line that the latches 145 bear (or are designed to bear). The chain tension on the chainwheel 115 is removed when the latches 145 are engaged with the chain in the closed position (i.e., latched onto the chain).

With reference to FIGS. 12A-12C, after latching the chain 131 with the latches of ILT 101, the lower portion of the chain 131b (tail chain) is laid upon the tail chain disconnecting table 109 and pinned via pin 129. In some embodiments, the pinning of the chain 131b to the table 109 is performed using an ROV that is docked on the table 109. The lower portion of the chain 131b includes a removable link 130a-130c. The removable link 130a-130c is a chain link that can be opened and closed, such that the removable link 130a-130c can be selectively attached and detached from the remainder of the chain 131. For example, the removable link 130a-130c may be a D-link or the like. Removable link 130a is shown in a flat orientation on table 109 in FIG. 12A, with link 130a positioned on track 114. Removable link 130b is shown in a vertical orientation on table 109 in FIG. 12B, with link 130b positioned in slot 112. Removable link 130c is shown in a hanging orientation on table 109 in FIG. 12C, extending upwards from table 109. The removable link can be passed through the ILT 101 and around the chainwheel 115 in a vertical or flat orientation, giving a mooring installation contractor the ability to choose which orientation is preferred for removal after tensioning.

With reference to FIGS. 13A and 13B, when the end of the chain 131b is pinned into place on the tail chain disconnecting table 109, the chainwheel 115 can be removed from the ILT 101, such as by removing two ROV compatible pins on each side of the chainwheel 115 and then hauling the chainwheel 115 up using an AHV. Chainwheel 115 can be disconnected from frame 103 of ILT 101 and lifted therefrom. For example, wire 175 can be lowered, such as from a winch or crane on an AHV. Wire 175 can include a hook 176 that engages with handle 173 for lifting chainwheel 115.

The chain disconnecting table 109 provides a structure where the chain 131b can be positioned and secured, and provides a dock for an ROV to engage the tail chain disconnecting table 109 to disconnect the chain 131b. To make the operation easier and to stabilize the ROV during disconnection of the chain, the dock of the tail chain disconnecting table 109 includes interface funnels 111 that can include locking features for engagement with and locking with an ROV. The interface funnels 111 allow an ROV to be docked onto the tail chain disconnecting table 109. The ROV docking interface funnels 111 are positioned on both sides of the disconnecting table 109 to provide options to the ROV operator to approach from either side of the ILT 101. As the manipulators of the ROV are not required for holing the ROV onto the table 109, all manipulators of a docked ROV may be free for use in disconnecting the tail chain (rather than using one of the ROV manipulators to hold onto the disconnecting table 109). The docking of the ROV allows the ROV to easily control the chain locking pin 129 as it is removed so that it is not dropped. The chain locking pin 129 on the disconnecting table 109 is used to facilitate the disconnecting operations. The chain locking pin 129 can be guided and captured by the ROV so there is reduced risk of dropping the chain locking pin 129. The chain locking pin 129 is positioned outside of the mooring load path and can be configured to meet corrosion requirements for the life of the mooring line. The chain locking pin 129 locks a position of the chain 131 onto the disconnecting table 109 by being pinned over a link of the chain 131.

With reference to FIG. 14, the chainwheel 115 is removed from the ILT 101 and ROV 201 is docked onto table 109 for operations to disconnect the removable link of chain 131 from the remainder of chain 131. Stabbing pins 203 of ROV 201 are engaged within funnels 111. The removable link 130 provides for the disconnection of the work chain 131 from the mooring chain after tensioning is completed. As the final mooring length can be calculated accurately (e.g., using the target link stopper 113), the position of the link 130 of the chain 131 can also be calculated accurately, such that the link 130 can be installed at the correct location along the chain 131. The link 130 may be removed by removing pin 171 threaded into the 130 (e.g., threaded using ACME threads which offer high strength and are self-locking so the pin will not tend to unthread itself). This removal of pin 171 can be accomplished using ROV 201. For additional security, a safety wire (not shown) can be used to ensure that the pin 171 is maintained fully threaded during operations. In such embodiments, prior to removing the pin 171, the ROV 201 may be used to cut the safety wire. In one example, the end of the pin 171 has an internal hex cavity that matches a male drive bit that is attached to an ROV torque tool. The ability to rigidly connect the ROV 201 to the table 109 via funnels 111 and pins 203 allows the ROV 201 to safely use a torque tool. That is, the ability to rigidly connect the ROV 201 to the table 109 via funnels 111 and pins 203 (or other docking structures) prevents or reduces “swimming” by the ROV 201 while performing the disconnection task, such that the ROV 201 is static or substantially static relative to the ILT 101 during disconnection of the link 130. In some embodiments, when one manipulator 205a of the ROV 201 is used to removes pin 171 using a torque tool, another manipulator 205b of the ROV 201 can be used to capture the pin 171, such that there is a reduced chance of the pin 171 being dropped onto the seabed. While disconnection of the tail chain is described as involving removing a removable link, in other embodiments a link may be cut from the work chain. For example, an ROV may operate a cutting tool to cut a link of the work chain.

If the work chain 131 is installed into an ILT 101 on board an AHV before deployment, the orientation of the chain links can be preselected. The ILT 101 of the present disclosure can accommodate any orientation of chain links. Thus, using the ILT 101 of the present disclosure, a mooring installation contractor can decide which chain link orientation is most convenient for use in the particular application and circumstances, and is not limited to ensuring that the chain line has a particular orientation. Thus, the ILT 101 of the present disclosure has a flexibility of design that accommodates multiple positions for disconnection of the tail chain.

FIG. 15 depicts the ILT 101 incorporate into a mooring line, connecting chain 131a with chain 135, and with chain portion 131b pinned thereto via pin 129.

If, after mooring line tensioning is completed, paying-out of additional chain is required, an ROV connecting link can connect back onto the last exposed link of the work chain that is left on the chain disconnecting table 109. The disconnecting table 109 is configured such that the last link of the chain can be reconnected in either orientation (i.e., vertical or flat) in such a way as to be available and accessible for reconnection. Three different options for connecting link orientation and position are shown in FIGS. 12A-12C, as discussed above. With the chain 131 and chain 135 connected on an AHV prior to deployment, the decision can be made as to which orientation is best and easiest for future reconnection prior to deployment. As shown, the disconnecting table 109 includes a slot 112 for receipt of vertical links, and tracks 114 for receipt of flat links. However, the disconnecting table 109 is not limited to these particular structures, and may include other structures for receipt of and securing of chain links of vertical or flat orientation.

Another feature of flexibility in configuration of the disconnecting table 109 is that, if there is a need to disconnect additional length of chain (e.g., if more chain needs to be hauled), then an underwater diamond saw chain cutter can be used, optionally with modifications. For example, stabbing pins or other docking structures may be incorporated on the cutter to dock with (interface with) the receiving funnels 111 or other docking structures on the disconnecting table 109. Thus, the disconnecting table 109 provides a structure where the work chain 131 can be secured, and can serve as a docking station for either an ROV to perform disconnection or a chain cutter using a diamond wire saw.

Floating Vessels

In some embodiments, the mooring methods and equipment disclosed herein are used to more vessels of various types, such as an oil drilling or production platforms, floating production storage offloading (FPSO) vessels, offshore floating wind power foundations, floating fish farms, or any other offshore floating structure. The AHV disclosed herein may be a ship including one or more winches, cranes, shark jaws, stern rollers, ROVs, and other devices that may be used in the mooring of a vessel.

Mooring Line

The mooring lines disclosed herein may include one or more sections of line, each of which may be composed of the same material or of different materials. The various segments of mooring lines may be coupled together via shackles, H-Links or other connectors. The bottom chain 135 may be a pile forerunner coupled with an anchor at seafloor. The anchor may be a suction pile, driven pile, drag embedment anchor, gravity anchor, torpedo anchor, or another type of anchor positioned at seafloor. The bottom chain 135 may be pre-laid and wet stored on the seafloor at the site, prior to towing the vessel to the site, or may be laid on the seafloor after towing the vessel to the site.

In some embodiments, the in-line tensioner disclosed herein is configured to use a work chain that is smaller than the mooring line chain to tighten the mooring line, while saving weight and cost.

While specific embodiments and equipment are shown and described herein, one skilled in the art would understand that the methods, systems, and apparatus disclosed herein are not limited to these particular embodiments described.

Although the present embodiments and advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the disclosure. Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, composition of matter, means, methods and steps described in the specification. As one of ordinary skill in the art will readily appreciate from the disclosure, processes, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or later to be developed that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein may be utilized according to the present disclosure. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps.

Claims

1. An in-line tensioner for tensioning mooring lines, the in-line tensioner comprising: a frame, the frame configured to couple with a bottom chain of mooring line;latches coupled with the frame, the latches positioned to grip a top chain of mooring line; anda chainwheel, wherein the chainwheel has at least two configurations, the at least two configurations including a first configuration wherein the chainwheel is coupled with the frame and is positioned to guide a top chain of mooring line, and a second configuration wherein the chainwheel is decoupled from the frame.

2. The in-line tensioner of claim 1, wherein the frame comprises a chainwheel dock, the chainwheel dock configured to receive the chainwheel in the first configuration.

3. The in-line tensioner of claim 2, wherein the chainwheel is mounted on a chainwheel frame.

4. The in-line tensioner of claim 3, wherein in the first configuration the chainwheel frame is pinned with the frame.

5. The in-line tensioner of claim 3, wherein the chainwheel frame comprises pins, wherein the chainwheel dock comprises funnels, and wherein, in the first configuration the pins are engaged within the funnels and in the second configuration the pins are disengaged from the funnels.

6. The in-line tensioner of claim 3, further comprising a chainwheel handle coupled with the chainwheel frame, wherein the chainwheel handle is configured to couple with a line for lifting and removing the chainwheel from the frame.

7. The in-line tensioner of claim 3, wherein the chainwheel frame comprises counterweights configured to maintain orientation of the pins.

8. The in-line tensioner of claim 1, wherein, in the second configuration, a center of gravity of the in-line tensioner is below a chain line of the mooring line.

9. The in-line tensioner of claim 1, further comprising: a chain guide coupled with the frame, the chain guide positioned to guide a top chain of mooring line, wherein the latches are positioned between the chainwheel and the chain guide when the chainwheel is in the first configuration; andpads on the chain guide positioned to slidingly engage with a top chain of mooring line, wherein the chain guide comprises a first material and the pads comprise a second material, wherein the first material and the second material are different, and wherein the second material exhibits a lower coefficient of friction relative to a top chain sliding along the second material than a coefficient of friction exhibited by the first material.

10. (canceled)

11. (canceled)

12. (canceled)

13. (canceled)

14. The in-line tensioner of claim 1, further comprising: a tail chain disconnecting table integral with or coupled to the frame, wherein the tail chain disconnecting table is configured to receive and secure a tail chain of mooring line.

15. The in-line tensioner of claim 14, wherein the tail chain disconnecting table comprises a tail chain locking pin for securing a tail chain to the tail chain disconnecting table.

16. The in-line tensioner of claim 14, wherein the tail chain disconnecting table is configured to receive and secure a tail chain in a vertical orientation, a flat orientation, or a hanging orientation.

17. The in-line tensioner of claim 16, wherein the tail chain disconnecting table comprises a track configured to receive a tail chain in a flat orientation and a slot configured to receive a tail chain in a vertical orientation.

18. The in-line tensioner of claim 14, wherein the tail chain disconnecting table comprises a remotely operated vehicle dock, the remotely operated vehicle dock configured to receive and secure a remotely operated vehicle.

19. The in-line tensioner of claim 18, wherein the remotely operated vehicle dock comprises funnels configured to engage with pins of a remotely operated vehicle.

20. A mooring system, the mooring system comprising: a mooring line comprising a bottom chain and a top chain;an in-line tensioner comprising a frame and latches coupled with the frame, wherein the bottom chain is coupled with the frame, and wherein the latches are positioned to selectively grip the top chain such that a length of the top chain portion of the mooring line is adjustable;a chainwheel, wherein the chainwheel has at least two configurations, the at least two configurations including a first configuration wherein the chainwheel is coupled with the frame and is positioned to guide the top chain of mooring line, and a second configuration wherein the chainwheel is decoupled from the frame;a target link stopper coupled with the top chain, wherein the target link stopper is positioned along the top chain such that when the target link stopper engages the in-line tensioner the mooring line has a target length.

21. The mooring system of claim 20, wherein, at the target length, the target link stopper is positioned on an outboard side of the latches and a removable link of the top chain is positioned on an opposite side of the latches, wherein the removable link is a link that is selectively removable from the top chain.

22. (canceled)

23. The mooring system of claim 20, wherein, at the target length, the predetermined link of the top chain is positioned to be gripped by the latches.

24. (canceled)

25. The mooring system of claim 20, wherein, with the top chain moving in a first direction through the in-line tensioner, engagement of the target link stopper with the in-line tensioner prevents further movement of the top chain in the first direction.

26. The mooring system of claim 20, wherein the target link stopper comprises a first body and a second body, wherein the first and second bodies are coupled to each other about a portion of the top chain, and wherein a spring a coupled between the first and second bodies.

27. (canceled)

28. A method of mooring a floating vessel, the method comprising: providing an in-line tensioner comprising a frame, a chainwheel coupled with the frame, and latches coupled with the frame;providing a mooring line including a bottom chain and a top chain;coupling the bottom chain between the frame and an anchor;coupling the top chain with the chainwheel, and coupling a first end of the top chain with the floating vessel;adjusting a length of the top chain between the floating vessel and the in-line tensioner until the mooring line has a target length, wherein the chainwheel guides movement of the top chain during the adjusting;gripping the top chain with the latches when the mooring line has the target length; andremoving the chainwheel from the in-line tensioner while the mooring line has the target length.

29. The method of claim 28, wherein removing the chainwheel comprises unpinning a chainwheel frame of the chainwheel from the frame of the in-line tensioner, and lifting the chainwheel from the in-line tensioner.

30. The method of claim 29, wherein lifting the chainwheel from the in-line tensioner is performed using an anchor handling vessel.

31. The method of claim 28, further comprising: a chain guide coupled with the frame, the chain guide comprising pads positioned thereon;wherein, during the adjusting of the length of the top chain, the top chain slides along the pads, wherein the chain guide comprises a first material and the pads comprise a second material, wherein the first material and the second material are different, and wherein the second material exhibits a lower coefficient of friction relative to the top chain sliding along the second material than a coefficient of friction exhibited by the first material.

32. (canceled)

33. (canceled)

34. (canceled)

35. The method of claim 28, further comprising: a tail chain disconnecting table integral with or coupled to the frame;securing a tail chain of the top chain to the tail chain disconnecting table; andremoving at least some of the tail chain from the top chain.

36. (canceled)

37. (canceled)

38. (canceled)

39. (canceled)

40. (canceled)

41. (canceled)

42. (canceled)

43. (canceled)

44. The method of claim 28, further comprising: coupling a target link stopper with the top chain, wherein the target link stopper is positioned along the top chain such that when the target link stopper engages the in-line tensioner the mooring line has the target length;wherein adjusting the length of the top chain between the floating vessel and the in-line tensioner is performed until the target link stopper engages the in-line tensioner;and wherein gripping the top chain with the latches is performed when the target link stopper is engaged with the in-line tensioner.

45. (canceled)

46. (canceled)

47. (canceled)

48. (canceled)