A load emergency release assembly

Abstract

A load emergency release assembly 10 comprises a plurality of latches 16 arranged circumferentially around a load, each latch 16 comprises a first surface 22 for supporting said load by engaging a lip (figure 1, 20) of said load and a second surface 26 distal of said first surface 22 and a first axis therebetween. A rotatable member 24 is adjacent the latches 16, where the rotatable member 24 operates between a first and a second condition wherein: in said first condition said rotatable member 24 engages a plurality of said second surfaces 26 and prevents said latches 16 from rotating about said first axes; in said second condition said rotatable member 24 disengages said second surfaces 26, allowing said latches 16 to rotate about said first axes and said first surfaces 22 to disengage said lip of the load thereby releasing the load. An actuator 28 is adjacent the rotatable member 24 and is for rotating the rotatable member 24 about a second axis into the second condition. A method of release using the assembly is disclosed.

Description

Background to the Invention The present invention relates to a load emergency release assembly and to a method of releasing a load from a floating apparatus and relates particularly, but not exclusively, to a signal-controlled emergency release assembly for high-voltage cables connected to Floating Offshore Wind (FOW) facilities. Traditionally, flexibles (typically high-voltage cables, umbilicals and pipes) connected from subsea to offshore facilities (typically FOW and oil &gas facilities) are connected using a method that is low cost but permanent. However, these connections must be disconnected in cases of urgent maintenance requirements or in emergencies such as extreme weather or collisions. The method of disconnection must be simple for maintenance requirements, but also rapid in emergency situations. The current preferred method of disconnection to address these requirements is cutting through the flexibles which causes irreversible damage to the cables or pipes. As a result, to allow continued functioning of the facility, replacement flexibles must be sourced and installed which can be a costly, difficult and time-consuming operation. It is known in the FOW sector that frequent maintenance disconnections will be common practice for most FOW facilities. The vulnerability of these facilities in emergency situations also means that a remote disconnection system is highly desirable, especially given that rapid manual disconnection of tens or potentially hundreds of facilities is not currently possible, even with considerable notice of an emergency such as a storm. Preferred embodiments of the present invention seek to overcome or alleviate the abovedescribed disadvantages of the prior art. Summary of the Invention According to an aspect of the present invention there is provided a load emergency release assembly comprising: a plurality of latches formed from a first material and arranged circumferentially around a load, each latch comprising a first surface for supporting said load by engaging a lip of said load and a second surface distal of said first surface and a first axis therebetween; a rotatable member adjacent said latches, said rotatable member operating between a first and a second condition wherein: in said first condition said rotatable member engages a plurality of said second surfaces and prevents said latches from rotating about said first axes; in said second condition said rotatable member disengages said second surfaces, allowing said latches to rotate about said first axes and said first surfaces to disengage said lip of said load thereby releasing said load; and an actuator adjacent said rotatable member for rotating said rotatable member about a second axis into said second condition. The emergency release assembly is designed so that flexibles (typically high-voltage cables) can be structurally disconnected and released through a rapid sequence of events initiated manually or preferably by a remote signal. This is a simplified means of releasing the flexible without damaging it, eliminating the need to source expensive replacement parts. Furthermore, as the reconnection procedure is far more simple than the installation of new flexibles, facility operations can be restarted more quickly. As the disconnection can be remotely signal-controlled, facilities can be disconnected promptly ahead of emergency situations, such as adverse weather or an imminent collision, that have potential to damage the flexible, the facility, or both, which has potential to be another significant cost-saving measure. In a preferred embodiment, said second surface comprises a removable component formed from a second material that is different to said first material. The load-supporting surface of the latches include a removable component (typically a reaction pad bolted to the latch surface) that is preferably formed from a non-metallic material. This reduces corrosion of the latch surface and the lip of the load, which are both typically formed from metallic materials and thus susceptible to corrosion, especially when underwater. In another preferred embodiment, said load comprises at least one of a cable and a pipe. In FOW facilities, loads that must be disconnected in the above-described situations are most commonly flexibles which are typically high-voltage cables and / or pipes. In an additional preferred embodiment, said actuator comprises a linear actuator. In a further preferred embodiment, said linear actuator comprises a hydraulic ram, said hydraulic ram comprising a piston and a cylinder wherein operation of said hydraulic ram extends said piston away from said cylinder. Having the release assembly operated by a hydraulic ram means that the system can be both initiated manually or by a remote signal. In a preferred embodiment, said cylinder and piston are joined together by a frangible plate, said plate comprising first and second plate sections wherein said first plate section is fixed to said piston and said second plate section is fixed to said cylinder. Inclusion of a frangible plate as part of the hydraulic ram prevents creep of the piston away from the cylinder which could otherwise cause premature release of the load and therefore unwanted disconnection of the facility In another preferred embodiment, operation of said hydraulic ram causes a breakage of said plate between said first and second plate sections when the force applied by said hydraulic ram exceeds a pre-determined value. In an additional preferred embodiment, rotation of said rotatable member by said hydraulic ram into said second condition only occurs after breakage of said plate. The frangible plate is constructed such that it will only break after a pre-determined amount of force is applied across it by the hydraulic ram. The amount of force applied from natural creep of the piston is insufficient to cause breakage of the plate, thus the piston is held in place and prevented from rotating the rotatable member and initiating release of the load. When the hydraulic ram is operated normally, extension of the piston away from the cylinder produces sufficient force to break the frangible plate and initiate release of the load. In a further preferred embodiment, said hydraulic ram is operated by a signal-controlled power unit. In most cases, it is preferable to initiate release of the load and disconnection of the facility remotely. This is most easily achieved using a signal-controlled power unit, which can power extension of the piston when operated remotely, preferably by pressing a button in a control room onboard the facility or onshore. This allows efficient disconnection of the facility from a remote location which is of significant benefit to the FOW industry. In a preferred embodiment, said hydraulic ram is operated by a manual pump. In certain situations, such as when there is a loss of power to the facility, it may not be possible or preferable to disconnect the facility remotely using a signal-controlled system. In such cases it may be preferable to carry out the disconnection manually using a pump to initiate operation of the hydraulic ram. In another preferred embodiment, said latches further comprise axles allowing said latches to rotate about said first axes. As action of the emergency release assembly depends on rotation of each latch about an axis, allowing them to disengage the lip of the load and thus release it, it is preferable for their rotation to be about an axle. Inclusion of axles allows the rotation axis of the latches to be precisely determined, while securing the latches to the release assembly as they move. In an additional preferred embodiment, said first axis is closer to said first surface than said second surface. By having the first axis closer to the first surface, the advantage is provided that, with the latch acting as a first class lever, a mechanical advantage is created which reduces the force applied by the second surface of the latch to the rotatable member. In a further preferred embodiment, said latches are supported from underneath by a plurality of curved surfaces adjacent said rotatable member. By supporting the latch on a curved surface the advantage is provide that the force of the latch onto its adjacent supporting component is distributed over a large surface area and removes any significant forces from the axles which can then simply be present to hold the latches in place. In a preferred embodiment, said load emergency release assembly is for a load connected to a floating offshore wind facility. FOW facilities require frequent disconnections of their flexibles (high-voltage cables and pipes) both for maintenance and in emergency situations. As current practice involves cutting and later replacing existing cables, which is both expensive and time-consuming, there is a considerable need for these facilities to have a quicker and more economical alternative disconnection method. According to another aspect of the present invention, there is provided a connector for connecting a flexible elongate member to a floating apparatus, the connector comprising: an end connector for a cable having a circumferential recess thereby forming a lip; and a load emergency release assembly as set out above. Although the release assembly is primarily targeted at FOW facilities, other floating apparatuses (such as boats) may benefit from the same device. According to an additional aspect of the invention, there is provided a method for releasing a load from a floating apparatus, comprising the steps: rotating a rotatable member, said rotatable member being adjacent a plurality of latches, said latches being formed from a first material and being arranged circumferentially around said load, each latch comprising a first and a second surface, said first and second surfaces being distal to each other and having a first axis therebetween, said rotatable member being rotated between a first and a second condition about a second axis by an actuator wherein: in said first condition said rotatable member engages a plurality of said second surfaces and prevents said latches from rotating about said first axes, thereby forcing said latches to engage a lip of said load with said first surfaces and preventing the release of said load; in said second condition said rotatable member disengages said second surfaces, allowing said latches to rotate about said first axes and said first surfaces to disengage said lip of said load thereby releasing said load. Brief Description of the Drawings Preferred embodiments of the present invention will now be described, by way of example only, and not in any limitative sense with reference to the accompanying drawings in which: Figure 1 is a cross-sectional view of an emergency release assembly of the present invention; Figure 2 is a pair of perspective views (one exploded and one assembled) of a component referred to as a latch that is used in the present invention; Figure 3 is a pair of perspective views (one exploded and one assembled) of a component referred to as a rotatable member that is used in the present invention; Figure 4 is a series of exploded views illustrating how the latches and rotatable member, of figures 3 and 4 respectively, fit together; Figure 5 is a pair of perspective views of a hydraulic ram that is used in the present invention; Figure 6 is a pair of close-up perspective views showing operation of the hydraulic ram of figure 5; Figure 7 is a series of views (perspective on the left and cross-sectional on the right) illustrating the rotating action of the latches of the present invention; Figure 8 is a pair of cross-sectional views illustrating how the rotating action of the latches causes release of the end-fitting according to the present invention; Figure 9 is a pair of perspective views illustrating how the rotating action of the latches causes release of the end-fitting according to the present invention. Figure 10 is a close-up view of the end-fitting illustrating circumferential bands marked on its surface used to aid mounting of the end-fitting to the emergency release assembly according to the present invention; Figure 11 is a pair of perspective views illustrating the end-fitting being mounted to the emergency release assembly according to the present invention; Figure 12 is a series of perspective and cross-sectional views illustrating the latches being rotated into position to finish the process of mounting the end-fitting according to the present invention; and Figure 13 is an exploded view illustrating the full set of components making up the emergency release assembly according to the present invention. Detailed Description of the Invention Referring initially to figure 1 there is provided a load emergency release assembly 10. In this example the assembly 10 is shown fitted in situ to an end-fitting 12 which connects a high-voltage cable 14 to a Floating Offshore Wind (FOW) facility. The end-fitting 12 and cable 14 together form the load that is to be released by the emergency release assembly. The assembly 10 comprises a number of latches 16 housed in a support plate 18 and arranged circumferentially around the end-fitting 12. The latches 16 support the end-fitting 12 by engaging a lip 20 of the end-fitting with a first surface 22. The assembly 10 further comprises a rotatable member 24 situated above the latches 16 and surrounding the end-fitting 12. The rotatable member 24 engages a second surface 26 of each latch 16 which prevents rotation of the latches. The assembly 10 additionally comprises a hydraulic ram 28 adjacent the rotatable member 24. A guide cone 30 which surrounds the end-fitting 12 and has a series of countersunk holes 31 is fitted above the rotatable member 24. The latches 16 are shown in more detail in figure 2. The second surfaces 26 have fixed to them a removable component 32, preferably formed from a non-metallic material, which provides a surface for engagement by the rotatable member 24. The rotatable member 24 is shown in more detail in figure 3. Substantially circular in shape the rotatable member 24 has fixed to it a first extension 34 to which the hydraulic ram 28 is connected (shown in figure 5). Positioned circumferentially around the rotatable member 24 are a series of recesses 36 interspersed by blocking segments 38. The arrangement of the latches 16 and rotatable member 24 is shown in figure 4. The latches 16 have a curved portion to their bottom surface which sits on a corresponding curved surface 40 of a curved plate 41 which sits on the support plate 18 (figure 4a). Each latch 16 additionally comprises an axle 42. The axle 42 is located at a first axis of rotation of the latch which results from the interaction of the curved surface of the latch with the corresponding curved surface 40 of curved plate 41 (figure 4b). The axles 42 (and therefore the axis of rotation) are most preferably located such that the first axis is closer to the first surface 22 than the second surface 26 of each latch 16. In the embodiment shown, a series of six latches 16 are arranged circumferentially around a substantially circular gap in the centre of the assembly which would normally house the end-fitting 12 when in operation (figure 4c). The axle 42 is not essential to the performance of the latch. The axle 42 is primarily present to help retain the latches 16 in place as the guiding of the rotation of the latches is controlled by the engaged curve bottom surface of the latch and the curved surface 40 of the curved plate 41. The hydraulic ram 28 is shown in more detail in figure 5a and as part of the release assembly in figure 5b. The ram 28 comprises a piston 44 and a cylinder 46 joined together by a frangible plate 48. The piston 44 is connected to the first extension 34 of the rotatable member 24. The cylinder 46 is connected to both a second extension 50 of the support plate 18 and a third extension 52 of a covering plate 54 which is positioned above the rotatable member 24. The frangible plate 48 comprises a first plate section 56 and a second plate section 58 joined together by a section of structural weakness 60 in between which prevents creep of the piston 44 away from the cylinder 46. The first plate section 56 is fixed to the piston 44 and the second plate section 58 is fixed to the cylinder 46. A pin 47 extends through an aperture in the end of the piston 44 and through another aperture in the first extension 34. The aperture in the first extension 34 has a diameter smaller that the diameter of the pin 47 where it extends through the aperture so that the pin is a loose fit with a few millimetres of clearance. Operation of the emergency release assembly will now be described with additional reference to figures 6 to 8. The assembly 10 is fitted to an end-fitting 12 which connects a high-voltage cable 14 to a FOW facility. The end-fitting 12 and cable 14 together form the load that is to be released by the assembly 10. When the load needs to be released, for instance in an emergency situation or for planned maintenance, the user presses a release button or operates a manual pump that is connected to the hydraulic ram 28. This initiates extension of the piston 46 away from the cylinder 48 which causes breakage of the frangible plate 50 at the section of structural weakness 60 into respective first and second plate sections 56 and 58. The piston 46 is shown non-extended in figure 6a and partially extended (sufficient to break the frangible plate 50) in figure 6b. As the piston 46 is connected to the first extension 34 of the rotatable member 24, extension of the piston causes rotation of the rotatable member which in turn allows rotation of the latches 16 and release of the end-fitting 12 of cable 14. The rotating action of the latches 16 is shown in figure 7. Figure 7a shows a perspective (left) and cross-sectional (right) view of a non-rotated latch 16 in the "loaded" position, while figure 7b shows the same views of a rotated latch in the "released" position. Prior to rotation, the rotatable member 24 is positioned such that the blocking segments 38 prevent rotation of the latches 16 about the first axes on their axles 42 by covering the removable component 32 of the second surface 26 of each latch with a portion 62 of the blocking segments. After rotation, the rotatable member 24 is positioned such that the blocking segments 38 no longer cover the removable component 32 of the latches 16. Instead, the recesses 36 are positioned directly above the removable component 32 and second surface 26 of each latch 16. As a result of the weight of the end-fitting 12 and cable 14 pulling downwards, the latches 16 are able to rotate about the first axes on their axles 42 with the second surfaces 26 of each latch 16 extending into the recesses 36. As a result, the first surface 22 of each latch disengages the lip 20 of the end-fitting 12. As the end-fitting 12 is no longer supported, the load is released. Figures 8 and 9 show the position of the latches 16 and end-fitting 12 before (left) and after (right) initiating the emergency release. Mounting of the end-fitting 12 with attached cables 14 to the emergency release assembly 10 will now be described with additional reference to figures 10 to 12. The end-fitting 12 to be pulled through the central bore of the assembly 10 preferably has circumferential bands marked on its surface used to identify its position during mounting. The frangible plate 50 is detached from the hydraulic ram 28. The piston 46 is then manually extended by operating the pump, which rotates the rotatable member 24 such that the blocking segments 38 no longer cover the second surface 26 or removable component 32 of the latches 16. Although the latches 16 are now free to rotate about their first axes, this is normally initiated by the weight of the end-fitting on the first surface 22 of the latches. Therefore, the latches 16 must be manually rotated into the "released" position by firmly tapping on the first surfaces 22 with a suitable tool such as a mallet until they are clear of the central bore through which the end-fitting 12 will be inserted. The end-fitting 12 is then pulled through the central bore, preferably with the assistance of a winch, until the lip 20 is clear of where the second surfaces 22 protrude into the central bore when the latches 16 are rotated back into the "loaded" position (figure Ila). The end-fitting 12 is then lowered back into the assembly 10 until the wide circumferential band 64 is just visible above the assembly 10 without looking down into the guide cone 30 (figure lib). The latches 16 are manually rotated back into the "loaded" position by insertion of reset tools 66 into the countersunk holes 31 of the guide cone 30. The reset tools 66 are used to push down on the second surface 26 or removable component 32 in order to rotate each latch 16 on its first axis back into the "loaded" position (figure 12). The reset tools 66 are then removed and retained. The piston 46 is retracted using the pump which rotates the rotatable member 24 such that the blocking segments 38 again cover the latches 16. The frangible plate 50 is reattached to the hydraulic ram 28. The end-fitting 12 is lowered further until the first surfaces 22 of the latches 16 engage the lip 20 of the end-fitting. The narrow circumferential band 68 should be just visible above the assembly 10 when looking down into the guide cone 30 at this point. The assembly 10 can now be used to perform an emergency release of the end-fitting 12 and attached cables 14. It will be appreciated by persons skilled in the art that the above embodiments have been described by way of example only and not in any limitative sense, and that various alterations and modifications are possible without departure from the scope of the protection which is defined by the appended claims. In particular, where various embodiments and aspects of the invention have been described above, features and steps of the apparatus and method are interchangeable between the embodiments and aspects of the invention. For example, it would be possible to replace the hydraulic ram 28 with another assembly that suitably rotates the rotatable member 24 to uncover the latches 16. This could be achieved using a series of cogs in a gear assembly or a worm gear and at least partially toothed rotatable member 24 or any other suitable mechanism to initiate rotation of the rotatable member. The lip 20 is the upper edge of a circumferential recess formed in the end-fitting 12. Alternatively, this circumferential recess could be replaced with a series of indentations formed around the outer surface of the end-fitting 12 which would align with the latches 16. The assembly 10 as described above is most preferably used in facilities that utilise bellmouthtype cable protection systems. However, it is also suitable for use with bend-stiffener type cable protection systems. In this case, the assembly requires additional components in the form of a bend stiffener connector, an emergency release adapter, as well as a S3NVentus Release System (VRS) as described in the international patent application no. PCT / GB2023 / 053185 (incorporated herein by reference) fitted to the bottom of the end-fitting. When mounting the end-fitting 12 in an assembly 10 used in a facility that utilises the bend-stiffener type cable protection system, the VRS must be primed for an emergency release at the point at which the end-fitting is pulled clear of the central bore of the assembly, as described in the above-mentioned patent application. The assembly 10 as described above is also most preferably used to release flexibles from FOW facilities, but it would be suitable for use with other floating apparatuses such as boats, ships, and offshore oil &gas facilities.

Claims

1. A load emergency release assembly comprising:a plurality of latches formed from a first material and arranged circumferentially around a load, each latch comprising a first surface for supporting said load by engaging a lip of said load and a second surface distal of said first surface and a first axis therebetween;a rotatable member adjacent said latches, said rotatable member operating between a first and a second condition wherein:in said first condition said rotatable member engages a plurality of said second surfaces and prevents said latches from rotating about said first axes;in said second condition said rotatable member disengages said second surfaces, allowing said latches to rotate about said first axes and said first surfaces to disengage said lip of said load thereby releasing said load; andan actuator adjacent said rotatable member for rotating said rotatable member about a second axis into said second condition.

2. A load emergency release assembly according to claim 1, wherein said second surface comprises a removable component formed from a second material that is different to said first material.

3. A load emergency release assembly according to claim 1 or 2, wherein said load comprises at least one of a cable and a pipe.

4. A load emergency release assembly according to any preceding claim, wherein said actuator comprises a linear actuator.

5. A load emergency release assembly according to claim 4, wherein said linear actuator comprises a hydraulic ram, said hydraulic ram comprising a piston and a cylinder wherein operation of said hydraulic ram extends said piston away from said cylinder.

6. A load emergency release assembly according to claim 5, wherein said cylinder and piston are joined together by a frangible plate, said plate comprising first and second plate sections wherein said first plate section is fixed to said piston and said second plate section is fixed to said cylinder.

7. A load emergency release assembly according to claim 6, wherein operation of said hydraulic ram causes a breakage of said plate between said first and second plate sections when the force applied by said hydraulic ram exceeds a pre-determined value.

8. A load emergency release assembly according to claim 7, wherein rotation of said rotatable member by said hydraulic ram into said second condition only occurs after breakage of said plate.

9. A load emergency release assembly according to any preceding claim, wherein said hydraulic ram is operated by a signal-controlled power unit.

10. A load emergency release assembly according to any preceding claim, wherein said hydraulic ram is operated by a manual pump.

11. A load emergency release assembly according to any preceding claim, wherein said latches further comprise axles allowing said latches to rotate about said first axes.

12. A load emergency release assembly according to any preceding claim, wherein said first axis is closer to said first surface than said second surface.

13. A load emergency release assembly according to any preceding claim, wherein said latches are supported from underneath by a plurality of curved surfaces adjacent said rotatable member.

14. A load emergency release assembly according to any preceding claim, wherein said load emergency release assembly is for a load connected to a floating offshore wind facility.

15. A connector for connecting a flexible elongate member to a floating apparatus, the connector comprising:an end connector for a cable having a circumferential recess thereby forming a lip; anda load emergency release assembly according to any preceding claim.

16. A method for releasing a load from a floating apparatus, comprising the steps:rotating a rotatable member, said rotatable member being adjacent a plurality of latches, said latches being formed from a first material and being arranged circumferentially around said load, each latch comprising a first and a second surface, said first and second surfaces being distal to each other and having a first axis therebetween, said rotatable member being rotated between a first and a second condition about a second axis by an actuator wherein:in said first condition said rotatable member engages a plurality of said second surfaces and prevents said latches from rotating about said first axes, thereby forcing said latches to engage a lip of said load with said first surfaces and preventing the release of said load;in said second condition said rotatable member disengages said second surfaces, allowing said latches to rotate about said first axes and said first surfaces to disengage said lip of said load thereby releasing said load.12

Images