Systems and methods for adjusting the length of tension leg platform tethers - Patents.com

Abstract

To provide a system and a method for adjusting the length of a tension leg platform tether.SOLUTION: A link plate system connects a tether to TLP through a first pin and a second pin. The link plate system may include a plurality of link plates. Each link plate may include first holes sized to receive the first pin connecting the link plate to the TLP and second holes sized to receive the second pin connecting the link plates to a tether. The length of respective link plates may be sized, and holes of each link plate may be aligned and sized so that the distance between the first pin and the second pin is different for each link plate so as to enable adjustment of connection length between TLP and the tether.SELECTED DRAWING: Figure 2

Description

[Background technology]

[0001] This section is intended to provide relevant background information to facilitate a better understanding of the various aspects of the described embodiments. As such, it should be understood that these statements are to be read in this light, and not as admissions of prior art.

[0002] A Tension Leg Platform (TLP) is a floating platform that is anchored to the seabed foundation by mooring elements, often called tension legs, tethers, or tendons. The tendons are kept in tension at all times by ensuring a net positive TLP buoyancy under all environmental conditions. The tendons rigidly constrain the TLP against vertical offsets, essentially preventing heave, pitch, and roll, but they adaptively constrain the TLP against horizontal offsets, allowing limited surge, sway, and yaw. Each tether requires length adjustment so that all tethers can be equally tensioned under various uncertainties, such as variations in pile head elevation and tether length.

[0003] The ability to adjust the length of the tether is essential to the integrity of the tether system. In conventional TLP tether designs, the length adjustment mechanism is achieved by a length adjustment joint (LAJ), and a matching grooved segment grip that can lock the groove joint at any position. Without the LAJ, the tether is at risk of over-tensioning, which can lead to tether failure, or under-tensioning, which can lead to tether buckling and / or snatch loads depending on the type of tether body. Conventional length adjustment mechanisms involve large forged cylindrical structures, and hydraulically actuated segment receptacles. However, the LAJ is a relatively expensive component and is not suitable for some TLP projects.

[0004] An embodiment of a system for adjusting the length of a tension leg platform tether is described with reference to the following figures. The same numbers are used throughout the figures to reference like features and components. Features illustrated in the figures are not necessarily shown to scale. Certain features of the embodiments may be shown exaggerated in scale or in somewhat schematic form, and some details of elements may not be shown for clarity and conciseness. [Brief description of the drawings]

[0005] [Figure 1] FIG. 1 illustrates an isometric view of a tension leg platform (TLP) according to one or more embodiments.

[0006] [Diagram 2] FIG. 2 is a diagram of a TLP tether assembly according to one or more embodiments.

[0007] [Diagram 3] FIG. 3 is a 3D perspective view of the upper connector assembly of FIG.

[0008] [Figure 4] FIG. 4 is a plan view of a link plate system for use with the upper connector assembly of FIG. 3. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] The present disclosure describes a system for adjusting the length of Tension Leg Platform (TLP) tethers. The system provides an alternative to costly length adjustment joints typically used to adjust the length of tethers. Additionally, the system provides fine adjustment of each tether to ensure that the loads resulting from maintaining the position of the TLP are evenly distributed among all tethers.

[0010] 1 is an isometric view of a tension leg platform (TLP) 100, according to one or more embodiments. The TLP 100 includes a base 102 made of columns 104 connected via ringed pontoons 106. The columns 104 are coupled to tethers 108, which are secured to piles (not shown) driven into the ocean floor 110, as described in more detail below. The tethers 108 prevent vertical motion of the TLP 100, such as wave, pitch, and roll, while allowing limited horizontal motion, such as swell, rock, and yaw. The length of the tethers 108 is sized such that loads due to constraints on the TLP are evenly distributed across the tethers 108.

[0011] In the illustrated embodiment, the base 102 supports a wind turbine 112 used to generate power. However, the base 102 may also support a platform, such as an oil and gas production platform, or other type of offshore platform, suitable for use with a TLP.

[0012] Reference is now made to Figure 2, which is a diagram of a TLP tether assembly 200, according to one or more embodiments. The TLP tether assembly 200 includes a tether 202 that couples the TLP hull 204 to a piling 206 or other substructure on the ocean floor 208 via a top connector assembly 210 and a bottom connector assembly 212. The length of the tether 202 is based on the estimated distance between the piling 206 and the hull 204. In at least one embodiment, the tether 202 is made from a synthetic material. In other embodiments, the tether 202 may be made from a composite material, steel, or other suitable material known to those of skill in the art.

[0013] As shown in FIG. 3, the upper connector assembly 210 includes a mounting bracket 300, a biaxial joint 302, a pull head 304, a link plate 306, and an H-link 308. A particular tether may also optionally include a coupler 310. Additionally, the H-link 308 may alternatively be a Y-link for a particular tether. The mounting bracket 300 is coupled to both the hull 204 and the biaxial joint 302 via an upper connector pin 312 to couple the upper connector assembly 210 to the hull 204. The biaxial joint 302 is then further coupled to the link plate 306 via an upper link plate pin 314. Thus, the biaxial joint allows the upper connector assembly 210, and thus the tether 202, to rotate about the upper connector pin 312 and the upper link plate pin 314 while preventing vertical movement of the upper connector assembly 210.

[0014] Link plate 306 is further coupled to H-link 308 via lower link plate pin 316, which is further coupled to thimble 310 via H-link pin 318. Thimble 310 is further coupled to tether 202 (not shown in FIG. 3 ). H-link 308 allows for additional rotation about both lower link plate pin 316 and H-link pin 318. However, some embodiments may omit H-link 308 and thimble 310 may be coupled to link plate 306 via lower link plate pin 316.

[0015] Link plate 306 is used to vary the connection length between hull 204 and tether 202, as discussed in more detail below with reference to Figure 4. This allows compensation for the difference between the length of tether 202, based on the estimated distance between peg 206 and the top connector location on hull 204, and the actual distance between peg 206 and the top connector location on hull 204.

[0016] FIG. 3 shows the top connector assembly 210, while the bottom connector assembly 212 may include the same components and functions as described above with reference to FIG. 3, except that the mounting bracket 300 of the bottom connector assembly 212 is coupled to the post 206.

[0017] Referring now to Figure 4, Figure 4 illustrates link plate assemblies 400, 402, 404 for use with the upper connector assembly 210 of Figure 3. Each link plate 406, 408, 410 of the link plate assemblies 400, 402, 404 has an upper hole 412 through which the upper link plate pin 314 extends to connect the link plate 406, 408, 410 to the biaxial joint 302. The link plates 406, 408, 410 also have a lower hole 414 through which the lower link plate pin 316 extends to connect the link plate to the H link 308 or Y link shown in Figure 3.

[0018] The holes 412, 414 in each link plate are positioned and sized such that the distance 416 between the upper link plate pin 314 and the lower link plate pin 316 is different for each link plate 406, 408, 410. The distance 416 between the upper link plate pin 314 and the lower link plate pin 316 can be varied via the holes 412, 414 to allow adjustment of the distance between the upper link plate pin 314 and the lower link plate pin 316, and thus the connection length of the tether 202.

[0019] 4 and described below, the lower hole 414 may be slotted and a pin sleeve 418 may be disposed within the lower hole 414 and surround the lower link plate pin 316. The distance 420 between the lower link plate pin 316 and a lower end 422 of the lower hole 414 may be altered via the pin sleeve 418 to allow for adjustment. Thus, the link plate shown in FIG. 4 may be used to change the connection length between the tether 202 and the post 206.

[0020] 4 to allow for different connection lengths with the same link plates 406, 408, 410. The offset holes 424 in the pin sleeve 418 allow the pin sleeve 418 to be rotated 180° between two positions to change the distance 420 between the lower end 422 of the lower link plate pin 316 and the lower link plate pin 414, providing further adjustment of the distance 416 between the upper link plate pin 314 and the lower link plate pin 316.

[0021] Although FIG. 4 shows three link plates 406, 408, 410, the upper connector assembly 210 utilizes only a single link plate 406, 408, 410 at a time, as shown in FIG. 3, depending on the desired connection length. To determine the correct link plate 406, 408, 410, the post-construction connection length is determined, and a link plate 406, 408, 410 is selected for the connection length. The stake end of the tether 202 is first connected to the stake 206 via the bottom connector assembly 212. The top end of the tether is then pulled toward the TLP, and the upper connector assembly 210 is assembled to connect the tether to the TLP. If desired, a pin sleeve 418 may also be selected for the connection length and installed within the link plate 406, 408, 410 to allow further adjustment of the connection length.

[0022] Alternatively, this process may be reversed and the top end of the tether may first be connected to the hull 204 via the top connector assembly 210. The stake end of the tether 202 is then connected to the stake 206 at the bottom connector assembly 212 as described with the top connector assembly 210.

[0023] Further examples include the following:

[0024] Example 1 is a link plate system for connecting a tether to a TLP via a first pin and a second pin. The link plate system includes a plurality of link plates. Each link plate includes a first hole sized to receive a first pin that connects the link plate to the TLP and a second hole sized to receive a second pin that connects the link plate to the tether. The length of each link plate is sized and the holes of each link plate are positioned and sized such that the distance between the first pin and the second pin is different for each link plate to allow adjustment of the connection length between the TLP and the tether.

[0025] In Example 2, an embodiment of any preceding paragraph or combination thereof further includes the second hole being further sized to receive any one of a plurality of pin sleeves sized to receive the second pin, each pin sleeve of the plurality of pin sleeves enabling a different distance between the second pin positioned within the pin sleeve and a lower end of the second hole.

[0026] In Example 3, an embodiment of any preceding paragraph or combination thereof further includes at least one of the multiple pin sleeves is asymmetric and positionable to allow for two different connection lengths with the same pin sleeve.

[0027] Example 4 is an upper connector assembly for connecting a TLP to a tether. The upper connector assembly includes a biaxial joint configured to couple to the TLP, a link plate including a first hole and a second hole, a first pin extending through the first hole to couple the biaxial joint to the link plate, and a second pin extending through the second hole to couple the link plate to the tether. The distance between the first pin and the second pin is based on the connection length between the TLP and the tether.

[0028] In Example 5, any of the preceding paragraphs or combinations thereof further include a pin sleeve disposed within the second hole and sized to receive the second pin. The distance between the second pin positioned within the pin sleeve and the lower end of the second hole is based on the connection length.

[0029] In Example 6, an embodiment of any preceding paragraph or combination thereof further includes that the pin sleeve is asymmetric and positionable to allow for two different connection lengths with the same pin sleeve.

[0030] Example 7 is a tether assembly for connecting a TLP to a pile. The tether assembly includes a tether having a top end and a pile end, and a connector. The connector includes a biaxial joint configured to couple to one of the TLP or the pile, a link plate including a first hole and a second hole, a first pin extending through the first hole to couple the biaxial joint to the link plate, and a second pin extending through the second hole to couple the link plate to the tether. The distance between the first pin and the second pin is based on the connection length between either the tether and the TLP or the tether and the pile.

[0031] In Example 8, any of the preceding paragraphs or combinations thereof further include the connector further comprising a pin sleeve disposed within the second hole that receives the second pin. The distance between the second pin positioned within the pin sleeve and the lower end of the second hole is based on the connection length.

[0032] In Example 9, an embodiment of any preceding paragraph or combination thereof further includes that the pin sleeve is asymmetric and positionable to allow for two different connection lengths with the same pin sleeve.

[0033] In Example 10, an embodiment of any preceding paragraph or combination thereof further includes that the connector is a top connector configured to couple the TLP to the tether.

[0034] In Example 11, an embodiment of any preceding paragraph or combination thereof further includes the connector being a bottom connector configured to couple the stake to the tether.

[0035] In Example 12, an embodiment of any preceding paragraph or combinations thereof further includes that the tether comprises a polyester.

[0036] Example 13 is a TLP. The TLP includes a hull, a pile, a tether having a top end and a pile end, a top connector that couples the top end of the tether to the hull at a top connector location on the hull, and a bottom connector that couples the pile end of the tether to the pile at a bottom connector location on the pile. At least one of the top connector and the bottom connector includes a biaxial joint configured to couple to one of the TLP or the pile, a link plate including a first hole and a second hole, a first pin extending through the first hole to couple the biaxial joint to the link plate, and a second pin extending through the second hole to couple the link plate to one of the top end of the tether or the pile end of the tether. The distance between the first pin and the second pin is based on the connection length between one of the tether and the TLP or the tether and the pile.

[0037] In Example 14, an embodiment of any preceding paragraph or combination thereof further includes the top connector includes a biaxial joint coupled to the TLP at the top connector, a link plate, a first pin extending through the first hole to couple the biaxial joint to the link plate, and a second pin extending through the second hole to couple the link plate to an upper end of the tether. The distance between the first pin and the second pin is based on the connection length between the tether and the TLP.

[0038] In Example 15, an embodiment of any preceding paragraph or combination thereof further includes the bottom connector including a biaxial joint coupled to the pile at the bottom connector, a link plate, a first pin extending through the first hole to couple the biaxial joint to the link plate, and a second pin extending through the second hole to couple the link plate to the pile end of the tether. The distance between the first pin and the second pin is based on the connection length between the tether and the pile.

[0039] In Example 16, an embodiment of any preceding paragraph or combination thereof further includes at least one of the top connector and the bottom connector further includes a pin sleeve disposed within the second hole that receives the second pin. The distance between the second pin positioned within the pin sleeve and the lower end of the second hole is based on the connection length.

[0040] In Example 17, an embodiment of any preceding paragraph or combination thereof further includes that the pin sleeve is asymmetric and positionable to allow for two different connection lengths with the same pin sleeve.

[0041] In Example 18, an embodiment of any preceding paragraph or combination thereof further includes that the tether comprises a polyester.

[0042] Example 19 is a method of installing a TLP. The method includes coupling a stake end of a tether to a stake. The method also includes measuring a connection length between an upper end of the tether and an upper connector location on the hull of the TLP. The method further includes installing a link plate to the upper connector, the link plate including a first hole and a second hole, and a distance between a first pin of the upper connector extending through the first hole and a second pin of the upper connector extending through the second hole is based on the connection length. The method also includes coupling the upper end of the tether to the hull via the upper connector.

[0043] In Example 20, an embodiment of any preceding paragraph or combination thereof further includes that installing the link plate includes installing a pin sleeve in a second hole of the link plate that receives the second pin. A distance between the second pin positioned in the pin sleeve and a lower end of the second hole is based on the connection length.

[0044] In Example 21, an embodiment of any preceding paragraph or combination thereof further includes that the pin sleeve is asymmetric and positionable to allow for two different connection lengths with the same pin sleeve.

[0045] Certain terms are used throughout the specification and claims to refer to particular features or components. As one skilled in the art will appreciate, different people may refer to the same feature or component by different names. This document does not intend to distinguish between components or features that differ in name but not function.

[0046] As referenced throughout this specification, the words "one embodiment," "an embodiment," "a" embodiment, "embodiment," "some embodiments," "particular embodiments," or similar language means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of the disclosure. Thus, throughout this specification, these phrases or similar language may, but do not necessarily, all refer to the same embodiment.

[0047] The disclosed embodiments should not be construed or otherwise used as limiting the scope of the present disclosure, including the claims. It should be fully appreciated that the different teachings of the discussed embodiments can be employed separately or in any suitable combination to produce the desired results. In addition, those skilled in the art will appreciate that the description has broad applicability, and the discussion of any embodiment is merely an illustration of that embodiment, and is not intended to suggest that the scope of the present disclosure, including the claims, is limited to that embodiment.

Claims

1. An upper connector assembly for connecting a TLP to a tether, comprising: a biaxial joint configured to couple to the TLP; a link plate having a first hole and a second hole; a first pin extending through the first hole to couple the biaxial joint to the link plate; a second pin extending through the second hole to couple the link plate to the tether; a distance between the first pin and the second pin based on a connection length between the TLP and the tether; a pin sleeve disposed within the second hole and sized to receive the second pin, wherein a distance between the second pin positioned within the pin sleeve and a lower end of the second hole is based on the connection length; An assembly, wherein the pin sleeve is asymmetric and positionable to allow for only two different connection lengths with the pin sleeve, and wherein the pin sleeve is asymmetric and positionable to allow for only two different connection lengths with the pin sleeve.

2. 1. A tether assembly for connecting a TLP to a stake, comprising: a tether having a top end and a stake end; a connector, the connector comprising: a biaxial joint configured to couple to either the TLP or the pile; a link plate having a first hole and a second hole; a first pin extending through the first hole to couple the biaxial joint to the link plate; a second pin connecting the link plate to the tether, the second pin extending through the second hole; the distance between the first pin and the second pin is based on a connection length between either the tether and the TLP or the tether and the peg; the connector further comprises a pin sleeve disposed within the second hole to receive the second pin, the distance between the second pin positioned within the pin sleeve and a lower end of the second hole being based on the connection length; An assembly in which the pin sleeve is asymmetric and positionable to allow for only two different connection lengths with the pin sleeve.

3. The assembly of claim 2 , wherein the connector is a top connector configured to couple the TLP to the tether.

4. The assembly of claim 2 , wherein the connector is a bottom connector configured to couple the stake to the tether.

5. The assembly of claim 2 , wherein the tether comprises polyester.

6. A TLP, The hull and Stakes and a tether having a top end and a stake end; an upper connector coupling the upper end of the tether to the hull at an upper connector location on the hull; a bottom connector for coupling the stake end of the tether to the stake at a bottom connector location on the stake; At least one of the top connector and the bottom connector: a biaxial joint configured to couple to either the TLP or the pile; a link plate having a first hole and a second hole; a first pin extending through the first hole to couple the biaxial joint to the link plate; a second pin extending through the second hole to couple the link plate to one of the top end of the tether or the stake end of the tether; the distance between the first pin and the second pin is based on a connection length between either the tether and the TLP or the tether and the peg; At least one of the top connector and the bottom connector further comprises a pin sleeve disposed in the second hole receiving the second pin, and the distance between the second pin positioned in the pin sleeve and a lower end of the second hole is based on the connection length; The pin sleeve is asymmetric and positionable to allow for only two different connection lengths with the pin sleeve, TLP.

7. The upper connector is the biaxial joint coupled to the TLP at the top connector; The link plate; the first pin extending through the first hole to couple the biaxial joint to the link plate; the second pin extending through the second hole to couple the link plate to the upper end of the tether; The TLP of claim 6 , wherein the distance between the first pin and the second pin is based on a connection length between the tether and the TLP.

8. The bottom connector includes: the biaxial joint being coupled to the pile at the bottom connector; The link plate; the first pin extending through the first hole to couple the biaxial joint to the link plate; the second pin extending through the second hole to couple the link plate to the stake end of the tether; The TLP of claim 6 , wherein the distance between the first pin and the second pin is based on a connection length between the tether and the post.

9. The TLP of claim 6 , wherein the tether comprises polyester.

10. 1. A method of installing a TLP, comprising: coupling a stake end of the tether to the stake; measuring a connection length between an upper end of the tether and an upper connector location on the hull of the TLP; installing a link plate to an upper connector, the link plate comprising a first hole and a second hole, a distance between a first pin of the upper connector extending through the first hole and a second pin of the upper connector extending through the second hole being based on the connection length; and coupling the upper end of the tether to the hull via the upper connector.

11. 11. The method of claim 10, wherein installing the link plate includes installing a pin sleeve in the second hole of the link plate that receives the second pin, and the distance between the second pin positioned in the pin sleeve and a lower end of the second hole is based on the connection length.

12. The method of claim 11 , wherein the pin sleeve is asymmetric and positionable to allow for only two different connection lengths with the pin sleeve.

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