Lifting device for subsea tubing end fittings

Abstract

The present invention provides a suspension apparatus for a subsea tubing end fitting, the apparatus including: an annular latch mounting member including a through hole; a plurality of latches pivotally mounted on the annular latch mounting member, the latches configured for engagement with a subsea tubing end fitting passing through the through hole and pivotable between an engaged position and a released position; a frangible retaining member configured to hold at least one of the latches in the engaged position; and a housing defining a longitudinal axis of the apparatus and including the through hole aligned with the through hole in the latch mounting member, and one or more recesses configured to receive a portion of the latch when in their engaged position, the annular latch mounting member being longitudinally movable relative to the housing, and the apparatus further including spring means for biasing the latch mounting member and the recesses in the housing away from each other.

Description

[Technical Field]

[0001] The present invention relates generally to the field of subsea tubing and manifolds, and more particularly to the field of subsea tubing connections of flexible supply pipelines to fixed structures, including devices for limiting bends in the flexible tubing or supply pipelines. Specifically, the present invention relates to an improved suspension device for subsea tubing end fittings, which is adapted for installation without the intervention of marine equipment, such as bend stiffeners for cables connecting to floating offshore wind (FOW) facilities, and which allows for disconnection in the event of excessive tension in the subsea tubing. [Background technology]

[0002] Subsea operations often require the use of a series of tubes, also called "risers," to connect equipment on the seabed to a fixed structure above, such as an offshore floating platform or vessel. The series of tubes or risers typically includes a conduit or multiple conduits used for the safe transportation of feedstock (e.g., hydrocarbon production fluids such as crude oil or gas). The series of tubes or risers may include cables or control lines to allow remote control of any equipment from the surface structure (i.e., platform or vessel).

[0003] FIG. 1 illustrates an example of a typical setup for subsea operations, in which production fluid is transported from at least one subsea well 10 to a floating production, storage, and offloading facility 20, also referred to as an FPSO 20. A FOW (Floating Offshore Wind) wind turbine 95 may also be connected via a subsea cable 97. A flexible riser 30 (a series of tubes) is used to transport the production fluid from the well 10, or from the subsea production site in the case of multiple wells, to the FPSO 20 via a turret 40 mounted on the FPSO 20. To protect the flexible riser 30 from excessive cyclic bending due to movement that may be caused, for example, by waves, currents, or wind, or simply by the movement of the FPSO 20, one or more bend stiffeners 50 (only one connection is shown in FIG. 1 ) are typically used at the juncture where the flexible riser 30 enters a fixed structure (i.e., through an “I” or “J” tube 60).

[0004] In many cases, the bend stiffener 50 is installed on the "I" or "J" tube 60 via a detachable connector assembly 70. The detachable connector assembly 70 may include a male connector member 72 that fits onto the bend stiffener 50 and a female connector member 74 that fits onto the "I" or "J" tube 60. During installation, the male connector member 72 is attached to the bend stiffener 50, and the end fittings 32 of the risers 30 are positioned within and attached to the male connector member 72. Specifically, the end fittings 32 of the risers 30 pass through the bend stiffener 50 and into the through-holes of the male connector member 72 and are secured in place by, for example, a cam device, a simple clamping mechanism 78, a latching mechanism, or any other suitable interlocking mechanism (not shown). The end fittings 32 of the series of tubes 30 are typically attached to the male connector member 72 in a workshop.

[0005] The assembly (i.e., riser 30, end fitting 32, bend stiffener 50, and male connector member 72) is then transported to the desired subsea location and pulled toward and coupled with the female connector member 74 using wire lines 80 attached to the end fitting 32 of the riser 30. Once the male connector member 72 is properly positioned within the female connector member 74, it is fixedly interlocked with the female connector member 74 to form a secure connection between the bend stiffener 50 and the "I" or "J" tubing 60. After securing the male connector member 72 within the female connector member 74, the end fitting 32 is released from engagement with the male connector member 72 and the riser 30 is pulled up and through the bend stiffener 50, securing the "I" or "J" tubing in place on the FPSO 20.

[0006] In many cases, the locking and unlocking of the male and female connector members 72, 74, and the release of the riser end fitting 32 from engagement with the male connector member 72, is accomplished through external intervention, such as, for example, a subsea diver 90 or a remotely operated vehicle (ROV) 92. To at least minimize the time and / or expense and potential risks of using a subsea diver 90 or ROV 92, currently available connector assemblies have been improved to also use remotely operable latching and / or end fitting release mechanisms.

[0007] Removable coupling between the male and female connector members is typically achieved using a pivoting latch arm (see latch arm 76 in FIG. 1) attached to the female connector member and configured to contact and engage a lip or shoulder portion of the male connector member, such that the male connector member "hangs" from the latch arm, which projects radially inward.

[0008] However, for this type of interlocking engagement, any relative movement between the male and female connector members can apply substantial stress to the latch arms and the engaging lip or shoulder of the male connector member. Specifically, any axial displacement between the male and female connector members can "rock" the lip or shoulder up and down when located on the respective latch arms during engagement, thus repeatedly hammering the latch arms to the point of potential failure. Furthermore, currently available latching mechanisms may allow for small relative movements between the male and female connector members (e.g., caused by movement of a floating structure, wave or wind movement through a series of tubing, or even pressurized fluid pumped through a conduit(s)), but at the expense of increased risk of damage due to repeated high pressures, shear stresses, fatigue and wear from uneven engagement and / or continuous movement between the contacting surfaces between the male and female connector members.

[0009] Subsea tubing is subjected to continuous changes in applied loads. It is therefore desirable that end fittings and I- or J-tubes automatically disconnect upon application of excessive loads to prevent damage. However, it is also desirable that such automatic disconnection be able to withstand increased loads greater than nominally excessive levels applied for only a fraction of a second, ensuring that disconnection occurs only if the excessive loads are applied for a sufficient period of time that damage would otherwise occur. Summary of the Invention [Means for solving the problem]

[0010] In accordance with the present invention, a suspension device for an end fitting of a subsea tubing comprises: an annular latch mounting member including a through hole; a plurality of latches pivotally mounted on the annular latch mounting member, the latches configured for engagement with end fittings of subsea tubing passing through the throughbore and pivotable between an engaged position and a released position; a frangible retention member configured to retain at least one of the latches in an engaged position; and a housing defining a longitudinal axis of the device and including a through-hole aligned with the through-hole of the latch mounting member and one or more recesses configured to receive a portion of the latch when they are in the engaged position; Including, The annular latch mounting member is vertically movable relative to the housing, and the apparatus further includes spring means for biasing the latch mounting member and the recess in the housing away from each other.

[0011] Such a device would allow the latches to pivot to their released position, thereby releasing the end fittings, when sufficient excess force is applied to the subsea tubing to overcome the bias of the spring means, but the provision of a frangible retaining member would ensure that the latches are still held in their engaged position if an increased load, greater than that which would normally be sufficient for the latches to release, is applied for only a fraction of a second. However, if the increased load on the tubing continues to be applied, the fuse bolt would blow, allowing the latches to pivot to their released position, thereby releasing the end fittings.

[0012] Preferably, the suspension device includes a plurality of frangible retention members, each configured to retain the latch in the engaged position.

[0013] Preferably, each of the latches includes a frangible retaining member configured to retain it in the engaged position.

[0014] Preferably, the or each frangible retaining member is secured to the latch and to a portion of the housing.

[0015] The or each frangible retaining member may include a fuse bolt.

[0016] The suspension device may include a plurality of springs for biasing the latch mounting member and the recess in the housing away from each other.

[0017] The plurality of springs may include a plurality of compression springs.

[0018] Each of the compression springs may be mounted within a spring housing.

[0019] The latch may be configured to be pivotable to an engaged position by engagement with an end fitting of the subsea tubing as the latch moves through the throughbore of the annular latch mounting member.

[0020] Each of the latch members may include a protrusion configured to engage a recess in the end fitting of the subsea tubing as the latch member moves through the through hole in the annular latch mounting member.

[0021] Each of the latch members may include a hook-like end configured to engage a recess in the housing when in the engaged position.

[0022] The suspension device may include a tubular housing.

[0023] The housing may include a plate member having one or more recesses.

[0024] Preferably, the plate member is annular.

[0025] The plate member may be formed from multiple assembled portions.

[0026] The annular latch mounting member may be formed from multiple assembled sections.

[0027] By way of example only, specific embodiments of the present invention will now be described with reference to the accompanying drawings, in which: [Brief explanation of the drawings]

[0028] [Figure 1] An example of a typical offshore setup for producing hydrocarbons from a subsea well and transporting the fluids to and from an FPSO via a flexible riser, protected by bend stiffeners at the point where the riser enters the FPSO's "I" or "J" bend. [Figure 2] 1 is a perspective view of one embodiment of a suspension device for a subsea tubing end fitting according to the present invention shown attached to an "I-tube." FIG. [Figure 3] 3 is a perspective view of the suspension device of FIG. 2 shown on an enlarged scale. [Figure 4] FIG. 3 is a side view of the suspension device of FIG. 2. [Figure 5] FIG. 3 is a plan view of the suspension device of FIG. 2. [Figure 6] 6 is a cross-sectional view of the suspension device of FIG. 2 taken in the direction of arrow AA in FIG. 5. [Figure 7] 5 is a cross-sectional view of the suspension device of FIG. 2 taken in the direction of arrow BB of FIG. 4. [Figure 8] 6 is a cross-sectional view of the suspension device of FIG. 2 taken in the direction of arrow CC in FIG. 5. [Figure 9] 6 is a cross-sectional view of the suspension device of FIG. 2 taken in the direction of arrow EE in FIG. 5. [Figure 10] FIG. 3 is a longitudinal cross-sectional view of the hanging device of FIG. 2 shown attached to an "I-tube" in an engaged mode. [Figure 11] FIG. 11 is a vertical cross-sectional perspective view of the suspension device shown in FIG. 10. [Figure 12] FIG. 3 is a longitudinal cross-sectional view of the suspension device of FIG. 2 shown attached to an "I-tube" in a released mode. [Figure 13] FIG. 13 is a vertical cross-sectional perspective view of the suspension device shown in FIG. 12. DETAILED DESCRIPTION OF THE INVENTION

[0029] The example embodiments described relate to a hanging device for an end fitting used with a subsea connector assembly, however, the invention is not limited to subsea applications and may be used with any other type of coupling that uses wire or cable to connect two tubular components.

[0030] Certain terms are used in the following description for convenience only and are not limiting. The words "right," "left," "bottom," "up," "front," "back," "upward," "downward," "downward," "up," "downward," "uphole," and "downhole" designate directions within the referenced drawings and relate to the described components when assembled and installed (e.g., in situ). Specifically, the designated directions used within the description relate to equipment installed within the facility to provide connections between the FPSO and subsea wells / reservoirs. Specifically, the terms "top," "upward," and "uphole" refer to the side of the equipment, in situ, that faces toward the water surface, and the terms "seabed," "down," and "downhole" refer to the side of the equipment, in situ, that faces toward the seabed or ocean floor. The words "inner," "inwardly," and "outer," "outwardly" refer to directions toward or away from, respectively, a designated centerline or geometric center (e.g., central axis) of the described element, with the particular meaning being readily apparent from the context of the description.

[0031] Furthermore, as used herein, the terms "coupled," "attached," "connected," and "mounted" are intended to include a direct connection between two members with no other members interposed therebetween, and an indirect connection between members where one or more other members are interposed therebetween. The terms include the words specifically mentioned above, their derivatives, and synonyms.

[0032] The term "bend stiffener" may refer to any one of a bend stiffener, bend restrictor, or bend limiter. The terms "fixed structure," "turret," "I-tube," and "J-tube" may be used interchangeably. "Riser" is understood to mean any series of tubing or supply pipeline suitable for operatively connecting a subsea well or any other subsea equipment with a fixed structure, for example, an FPSO vessel.

[0033] Furthermore, unless otherwise specified, the use of ordinal adjectives such as "first," "second," "third," etc., is intended only to indicate that different instances of similar objects are being referred to and is not intended to imply that the objects so described must be in a given order, either temporally or spatially, in ranking or in any other way.

[0034] Throughout the description and claims of this specification, the terms "comprise" and "comprises," and variations thereof, are intended to mean "including but not limited to," and they are not intended to (and do not) exclude other moieties, adjuncts, components, integers, or steps. Throughout the description and claims of this specification, the singular encompasses the plural unless the content requires otherwise. Specifically, where the indefinite article is used, the specification should be understood to contemplate the plural as well as the singular unless the content requires otherwise.

[0035] It should be understood that any feature, integer, property, compound, chemical moiety, or group described in connection with a particular aspect, embodiment, or example of the invention is applicable to any other aspect, embodiment, or example described herein, except where incompatible therewith. All features disclosed herein (including any accompanying claims, summaries, and drawings), and / or all steps of any method or process so disclosed, may be combined in any combination, except where at least some of such features and / or steps are mutually exclusive. The invention is not limited to the details of any of the foregoing embodiments. The invention extends to any novel one or any novel combination of the features disclosed herein (including any accompanying claims, summaries, or drawings), or any novel one or any novel combination of the steps of any method or process so disclosed.

[0036] One embodiment of a suspension apparatus 110 according to the present invention is illustrated in the drawings. In Figures 2 and 11-16, the suspension apparatus 110 is shown connected to the upper end of an "I-tube" 112, with an end fitting 114 attached to one end of a subsea tube 115.

[0037] 2-10, the suspension device 110 includes an annular split plate 116 to whose lower end a split flange interface 118 is coaxially connected using a plurality of bolts 120 extending through the flange interface 118 and into the lower end face of the annular split plate 116. The flange interface 118 is secured to a corresponding flange 113 at the upper end of the I-tube 112 by a plurality of identical fastening bolts 119. A coaxially mounted tubular funnel fixture 122, including four identical, angularly equally spaced support legs 124 defining four identical openings 126, is secured to the upper surface of the annular split plate 116 to support a coaxial frusto-conical funnel 128 at its upper end.

[0038] An annular latch mounting member in the form of a split annular mounting plate 130 is coaxially mounted to the split annular plate 116, split flange interface 18, tubular funnel mounting fixture 122, and frusto-conical funnel 128, which together define a longitudinal through passage or bore 132. The annular mounting plate 130 is retained by a split annular clamp 134 disposed around its outer edge.

[0039] Each of the annular split plate 116, the annular split flange interface 18, the tubular funnel fixture 122, the annular mounting plate 130, and the annular clamp 134 is formed from two semi-annular portions for ease of assembly, although each may alternatively be formed in one piece, as will be described.

[0040] The annular mounting plate 130 has four pairs of identical, planar, parallel mounting flanges 136, 138, each pair supporting a pivot pin 140 to which a latch in the form of a hanging collet 142 is pivotally mounted. The mounting flanges 136, 138 are secured to the upper surface of the annular mounting plate 130 by bolts 139 that pass through openings in the mounting plate and are received in threaded holes in the underside of each flange 136, 138 (FIG. 8).

[0041] Each of the hanging collets 142 is generally hook-shaped and pivotally mounted on a pivot pin 140 adjacent its upper end. Each collet 142 has a radially inwardly directed projection 144 at its upper end and a hook portion 146 at its opposite end. Each collet 142 is pivotable between a first, engaged position, shown in FIGS. 6, 11, 12, and 15, in which the projection 144 engages a corresponding recess 148 in the outer surface of the end fitting 114 and the hook portion 146 is hooked under a complementary-shaped peripheral projection 150 on the upper end of the divider plate 116, and a second, open position, shown in FIGS. 13, 14, and 16, in which the projection 114 is disengaged from the recess 148 in the end fitting 114 and the hook portion 146 is disengaged from the peripheral projection 150. It will also be seen that the inner surface of each collet 142 is configured to receive the outer periphery of the annular mounting plate and the upper end of the dividing plate 116 when in the first engaged position.

[0042] Each collet 142 is held in its engaged position by a fuse bolt 154 that passes through a hole 156 in the collet and is threadably received within a threaded hole 158 in the outer periphery of the annular mounting plate 130. Each fuse bolt 154 is also prevented from inadvertent release by a socket head bolt 160 that engages the head of the fuse bolt 154.

[0043] Eight identical preloaded spring assemblies 162 extend between the upper surface of the annular dividing plate 116 and the annular mounting plate 130 to bias the annular mounting plate 130 away from the annular dividing plate 116 to hold the collets 142 in their engaged position. Each spring assembly 162 includes a tubular spring case 164 within which is coaxially mounted a fixing bolt 166, the lower end of which is threadably received within a complementary threaded opening 168 provided in the upper surface of the dividing plate 116.

[0044] A compression spring 170 is disposed around each spring sleeve 166 and is preloaded to a set level. The lower end of each spring 170 is secured within an annular recess 172 in the upper surface of the dividing plate 116, and the upper end of the spring is retained by the upper end surface 173 of the tubular spring case 164. The lower end of the spring case has an increased outer diameter and is retained by a protruding shoulder 178 of the opening through which the spring case passes. The spring therefore biases the annular mounting plate upward, i.e., away from the dividing plate 116.

[0045] However, it should also be noted that fuse bolt 154 is configured to withstand a higher load than required to overcome the preload of spring 170 as described.

[0046] In use, the end fitting 114 on one end of the subsea tubing 116 is pulled through the I-bend 112, and the annular dividing plate 116, annular dividing flange interface 18, tubular funnel fixture 122, annular mounting plate 130, and annular clamp 134 are assembled around it by sliding the various unit halves together. At this assembly, the collets 142 are in their first engaged position, and the fuse bolts 154 are also installed. The end fitting 114 is thus held within the I-bend by the collets 142. The assembled suspension device 110 is then secured to the flange 113 at the upper end of the I-bend 112 using the securing bolts 119.

[0047] The subsea tube 116 is subjected to continuous changes in applied load. The preload applied to the compression spring 170 minimizes fatigue effects on the assembly from constant changes in tension applied to the tube 116. The preload applied to the compression spring 170 typically corresponds to at least 85% of the defined emergency release load. If the load applied by the compression spring is exceeded for an extended period by the load applied to the tube 116 (and by the expansion of the collet 142), the spring will compress, which will release the collet hook portion 146 from the peripheral protrusion 150. However, the fuse bolt 154 provides a backup in case of a sudden, very short-term load that exceeds the emergency release load for only a moment (e.g., if the tube 116 becomes temporarily stuck). In such a situation, the fuse bolt prevents the collet 142 from pivoting to their second, released position, allowing the system to return to normal once the temporarily increased load is relieved. However, if a load is applied for anything other than a very short period of time, the fuse bolt 154 is designed to break, which allows the collet 142 to pivot to a second, released position, as shown in Figures 13 and 14, releasing the end fitting 114 from the I-tube 112 and allowing it to move downward through the I-tube.

[0048] The present invention therefore results in automatic release of the end fitting from the I-tube 112 in the event of application of a load to the subsea tubing 116 that exceeds a predetermined emergency release load, but also prevents such automatic release if the applied load exceeds the load at which release would normally occur for only a moment.

[0049] The invention is not limited to the details of the foregoing embodiments.

[0050] For example, while in the embodiment described above the unit is assembled around the end fitting 114 after it is pulled through the I-beam 112, the split components could instead be provided as a complete (unsplit) unit. In that case, it would be assembled on top of the I-beam 112 before the end fitting 114 is pulled through it, in which case the collet 142 would be in the second, released position (without the fuse bolt 154 attached) and retracted from the through-hole 132 to allow the end fitting to pass through. The spring 170 would then need to be compressed by approximately 10 mm (using a removable stud and nut) to allow the hooked end 146 to engage the protrusion 150. The fuse bolt 154 would then be attached.

Claims

1. 1. A suspension device for an end fitting of a subsea tube, comprising: an annular latch mounting member including a through hole; a plurality of latches pivotally mounted on the annular latch mounting member, the latches configured for engagement with end fittings of subsea tubing extending through the throughbore, the latches pivotable between an engaged position and a released position; a frangible retention member configured to retain at least one of the latches in the engaged position; a housing defining a longitudinal axis of the device and including a through-hole aligned with the through-hole of the latch mounting member and one or more recesses configured to receive a portion of the latch when in their engaged position; Equipped with the annular latch mounting member is movable in the longitudinal direction relative to the housing, the apparatus further including spring means for biasing the latch mounting member and the recess in the housing away from each other. Hanging device.

2. The suspension apparatus of claim 1 including a plurality of frangible retention members, each configured to retain a latch in the engaged position.

3. The suspension apparatus of claim 2 , wherein each of the latches comprises a frangible retention member configured to retain it in the engaged position.

4. 10. A suspension device according to any preceding claim, wherein the or each frangible retention member is secured to a latch and to a part of the housing.

5. 10. A suspension device according to any preceding claim, wherein the or each frangible retention member includes a fuse bolt.

6. 10. A suspension apparatus according to any preceding claim, including a plurality of springs for biasing the latch mounting member and the recess in the housing away from each other.

7. 7. The suspension device of claim 6, including a plurality of compression springs.

8. The suspension device of claim 7 , wherein each of the compression springs is mounted within a spring housing.

9. 10. A suspension arrangement as claimed in any preceding claim, wherein the latch is configured to be pivotable to the engaged position by engagement with an end fitting of the subsea tubing as it moves through the through hole in the annular latch mounting member.

10. 10. The suspension apparatus of claim 9, wherein each of the latch members includes a protrusion configured to engage a recess in the end fitting of a subsea tubing as the protrusion moves through the through hole of the annular latch mounting member.

11. 10. A suspension device according to any preceding claim, wherein each of the latch members includes a hook-like end configured to engage a recess in the housing when in the engaged position.

12. 10. A suspension device according to any preceding claim, comprising a tubular housing.

13. 10. A suspension apparatus according to any preceding claim, wherein the housing includes a plate member having the one or more recesses.

14. The suspension device of claim 13 , wherein the plate member is annular.

15. 15. The suspension apparatus of claim 14, wherein the plate member is formed from a plurality of assembled sections.

16. 10. A suspension device according to any preceding claim, wherein the annular latch mounting member is formed from a plurality of assembled sections.

Images