GB2633304A

GB2633304A - An engagement mechanism for a mono-coupling

Info

Publication number: GB2633304A
Application number: GB2313216.0A
Authority: GB
Inventors: Michael Leuvan Mensah Jonathan; Robert Alexander Field Jonathan
Original assignee: MSCM Ltd
Current assignee: MSCM Ltd
Priority date: 2023-08-30
Filing date: 2023-08-30
Publication date: 2025-03-12
Also published as: GB202313216D0; WO2025045874A1

Abstract

The present invention provides an engagement mechanism 1 which is arranged to receive and house two halves 11, 23 of a coupling, to form an ROV mono-coupling. A flying part 3 of the mechanism is arranged to dock with a fixed part 2 of the mechanism, with a rotatable handle 7 on the flying part then operated by an ROV to cause a threaded member 24 to be rotated, to first lock the two parts together, before continued rotation of the handle subsequently connects the two halves of the coupling. The two parts may be locked together by an expanding dog 32 which is driven radially outwardly by cam member 28 to anchor the flying part into the fixed part.

Description

An Engagement Mechanism for a Mono-Coupling The present invention relates to an engagement mechanism for couplings to be operated by remotely operated vehicles (ROVs), particularly mono-couplings, which couplings may be used to connect tube and hoses on the seabed, such as hydraulic or pneumatic lines, to fixed structures, these lines can be used to transfer power or to inject a fluid or gas at a well head, for example.

Present coupling normally comprise two parts. A fixed part arranged to be attached to a fixed structure on the seabed, such as to a distribution manifold or to a Christmas tree mounted to a wellhead, with the second part of the coupling, the "flying" part, being attached to the end of a hydraulic or pneumatic line. Often, both ends of a pressure hose, or section of metal tubing, will terminate at a respective flying part of a mono-coupling, with the two flying parts and intervening hose, metallic tubing or similar, forming what is termed a single line jumper (or single line hydraulic flying lead).

Considering now the example of a hose, the flying part of a coupling is preassembled on one end of the hose and, in use, this will then need to be picked up and coupled remotely, by an ROV, to the fixed pad of the coupling, already mounted to a fixed structure. Often, a connection will be made to a live pressure supply, where the pressure of a fluid (liquid or gas) in one part of the coupling may be 10,000psi, requiring the ROV to not only position the flying part in place and couple it mechanically to the fixed part, but to also establish a fluid connection where the high pressures that may be present in one part of the coupling, could act to push the two parts of the coupling apart. This normally precludes a straight "push fit" by the ROV.

In addition to the above, because of risk of potential misalignment and subsequent risk of fouling a thread, together with the risk of damaging a thread on the initial coming together of the two parts of a coupling, direct threaded couplings are not commonly used in such remote applications.

An example of one presently known type of mono-coupling for the above type of application is the ROV mono-coupling, manufactured by MSCM Limited. This comprises two parts as described above, wherein the fixed part comprises a port into which the flying part of the coupling is inserted in an axial direction. The fixed part providing a bayonet coupling such that the flying part can be pushed into the port by the ROV in an axial direction and then rotated by the ROV about its axis through 90°. The action of rotation of the flying part initially engages pins on the flying part with ramps of the bayonet coupling on the fixed part, such that the flying part can no longer be axially withdrawn from the fixed part. Continued rotation of the flying part in the fixed part then causes the ramps of the bayonet coupling to urge the pins on the flying part forward in the axial direction as they rotate, drawing the two parts of the coupling together and establishing a hydraulic or pneumatic connection between the two parts of the coupling, against the force exerted by the supply pressure that may be present.

One limitation with the above described coupling arises because the maximum rotation of the flying part, available to fully engage with the bayonet coupling of the fixed part, is 90°. Furthermore, because part of this rotation is required to initially engage the pins of the flying part into the bayonet coupling of the fixed part, there is significantly less than 90° of rotation left to progress the flying part of the coupling forward sufficiently to fully open the hydraulic or pneumatic connection. This limited rotational range, together with the required forward axial displacement necessary to fully open the pneumatic or hydraulic connection, determines the pitch or incline of the ramps of the bayonet. This together with the maximum torque that is available from a drive unit on an ROV manipulator arm, limits the force that can be applied in an axial direction to bring the two parts of the coupling together to establish a hydraulic or pneumatic connection. The result of this is that if the coupling is to be used to connect to a live supply of a given pressure, this pressure will determine the maximum size of the coupling in terms of the cross sectional area of the flow line through the coupling.

Presently a 3/8" coupling is the maximum size of the above coupling type that can connect to a 10,000 psi supply.

Recently pressures of up to 15,000 psi have been used and greater flow rates and thus larger coupling sizes are also desired, which is not possible with the type of coupling described above.

In addition to the above, a problem that can arise with the current coupling is that if two fly couplings are used to terminate respective ends of a relatively stiff hose, pipe or a tube, then once the first coupling has been made at a first end, rotating the second fly coupling at the other end, to make the second coupling, can act to undo the first coupling.

It is an object of the present invention to provide an engagement mechanism 15 for an ROV mono-coupling.

According to a first aspect of the present invention there is provided an engagement mechanism for a remotely operated vehicle (ROV) mono-coupling, which engagement mechanism is arranged to be operated by an ROV and to receive and house two halves of a coupling, to form an ROV mono-coupling. The engagement mechanism comprising: a fixed part arranged to be connected to a fixed structure and to house a first half of the coupling; and a flying part, arranged to be connected to a hose, tube or pipe and to house a second half of the coupling, wherein: the fixed part of the engagement mechanism comprises a port in which the flying part may be docked; the flying part of the engagement mechanism comprises a rotatable handle to be rotated by an ROV; the flying part of the engagement mechanism comprises a threaded member rotated by the rotatable handle, and wherein, once the flying part of the engagement mechanism has been docked in the port of the fixed part, rotation of the rotatable handle by the ROV in a first direction causes the threaded member to first lock the flying part in the fixed part, with continued rotation of the threaded member in the first direction subsequently causing a second half of the coupling housed in the flying part of the engagement mechanism to establish a connection with the first half of a coupling housed in the fixed part of the engagement mechanism.

An engagement mechanism in accordance with the present invention provides the mechanical advantage offered by a screw thread, to both lock two parts of the engagement mechanism together and subsequently advance the second half of a coupling into connection with each other half, without the need to employ a direct conventional screw threaded coupling.

The single action of rotating the rotatable handle in a single direction, (which preferably requires at least five complete turns and more preferably ten complete turns) causes the flying part to first lock itself into the port of the fixed part before connecting the two halves of the coupling housed within the engagement mechanism. The screw threaded action can provide sufficient force to connect relatively large sizes of coupling together, where one may for example be at a live operating pressure of 15,000 psi, with no rotational forces being placed on a hose tube or pipe extending from the flying part.

An engagement mechanism in accordance with the present invention may typically be used to connect a 3/4 inch coupling having a live design pressure of 15,000 psi, or to connect a non-pressurised coupling to subsequently operate at a design pressure of 22,500 psi.

A further advantage of the present invention is that it permits a coupling to be used which is separate to the engagement mechanism used to connect the two halves of the coupling together. This enables a faulty damaged or worn coupling to be replaced without the need to replace the engagement mechanism. It may also permit different types of couplings to be used, so that the engagement mechanism need not be specific to one application or to one specific brand of coupling.

Preferably, the flying part is arranged to be inserted axially into the port to a predetermined position, prior to the rotatable handle being rotated by the ROV to lock the flying part in the fixed part. This provides the advantage that the engagement mechanism of the invention can be operated by presently available ROVs, without modification. The ROV can first dock the flying part of the engagement mechanism with the fixed part, by first generally aligning the flying part with the port of the fixed part and pushing the flying part into the port, prior to engaging with commences rotation of the rotatable handle.

Preferably the flying part comprises a main body having an engagement surface arranged to contact an engagement surface of a main body of the fixed part, to form a stop and limit insertion of the main body of the flying part into the main body of the fixed part. This enables the relative position of the main body of the flying part and the main body of the fixed part to be known, so that the distance that the second half of the coupling will need to be advanced to make connection with the first part can be minimised. This in turn enables the size and bulk of the engagement mechanism to be minimised and this also reduces the number of rotations of the rotatable handle that may otherwise be required to be made by the ROV, to connect the two halves of the coupling together.

Advantageously a visual indicator is provided to indicate to the ROV operator when the flying part has been fully inserted into the fixed part to the predetermined position. Thus, if the port should contain a foreign body preventing full insertion, this will enable the ROV operator to avoid unnecessary rotation of the handle, which would not be desirable if the flying part was not correctly docked.

The flying part may comprise a main body having an engagement surface arranged to contact an engagement surface of a main body of the fixed part, to form a stop and limit insertion of the main body of the flying part into the main body of the fixed part. This stop will ensure that the flying part can not be overly inserted, which could otherwise cause damage to a coupling housed therein.

Advantageously the main body of the of the flying part is prevented from rotating in the main body of the fixed part. This ensures that the action of rotating the rotatable handle does not act to rotate the flying part, for this would act to rotate any hose tube or pipe connected to the flying part.

Preferably the flying part comprises a carrier for the second half of the coupling, the carrier being threaded onto the threaded shaft, which carrier can move axially forward on the shaft as the shaft is rotated in a first axial direction and backwards on the shaft as the shaft is rotated in a second axial direction opposite to the first direction, wherein rotation of the handle in the first direction causes the carrier to move forward urging a locking device in the main body of the flying part to be displaced radially outward from the main body of the flying part, to engage with the main body of the fixed part, to lock the two parts together in the axial direction, prior to continued rotation of the handle and continued forward movement of the carrier pushing the second half of the coupling into engagement with the first half of the coupling. The action of rotating the screw thread can thus initially place significant force on the locking device ensuring correct and positive operation of the locking device, prior to that same screw thread exerting a significant force, in an axial direction, on the second half of the coupling, to ensure positive engagement of the two haves of the coupling against any resistance provided by appropriate seals and to open a connection between the two halves of the coupling, one or more of which may be connected to a pressurised supply of fluid.

The carrier may have one or more cammed surfaces wherein the locking device comprises one or more dogs which may extend through apertures in a main body of the flying part to engage with the fixed part, wherein, as the carrier first moves axially forward, the one or more cammed surfaces act to push the one or more dogs radially outward so that they extend through the apertures in the main body and engage with the fixed part and wherein the one or more dogs are retained in the extended outward position by a surface or surfaces of the carrier during the continued forward movement of the carrier.

The above arrangement permits the initial rotation of the rotatable handle to cause the dogs to be pushed outward and then causes them to be held in the outward "locked" position by the surface or surfaces of the carrier, as the carrier continues to moves forward to engage the two halves of the coupling.

The engagement mechanism may additionally further comprise biasing means which acts to retain the flying part of the engagement mechanism docked in the port of the fixed part, prior to the flying part being locked in the fixed part. An advantage of this is that, should the ROV release the fixed part, the biasing means will then act to retain the flying part in the fixed part, preventing the flying part being accidentally released from the port. This is particularly advantageous because it will normally be necessary for the ROV to release a manoeuvring handle of the flying part, used to guide the flying part into the port of the fixed part, in order for the ROV to engage with the rotatable handle.

The biasing means may be in the form the visual indicator provided to indicate to the ROV operator when the flying part has been fully inserted into the fixed part to the predetermined position, for this may be spring biased inwardly through a main body of the fixed part to engage with a groove of recess on the flying part.

Advantageously the flying part comprises a mounting for the second half of the coupler, which mounting is secured to the carrier and is interchangeable depending on the type of coupling housed in the engagement mechanism. More preferably the fixed part also comprises a mounting for the first half of the coupler, which is interchangeable depending on the type of coupling housed in the engagement mechanism. This permits different types of coupling to be used with the engagement mechanism.

This above arrangement also enables new designs of mountings to be designed and fitted to the engagement mechanism, to accommodate new designs 30 of couplings, avoiding the time and expense of designing a new engagement mechanism Preferably the mounting for the second half of the coupler comprises an engagement surface arranged to contact an engagement surface of the main body of the fixed part, to form a second stop that limits further forward travel of the mounting for the second half of the coupler. This prevents over insertion of the first half of a coupling into the second half of the coupling which could damage the coupling. Furthermore, because the interchangeable mounting for the second part of the coupling forms part of the stop, the mounting may be designed to restrict forward travel to a position appropriate for the type of coupling it is intended to be used with.

Preferably the engagement mechanism comprises a visual indicator to indicate when the mounting for the second half of the coupler has reached the second stop. The indicator will confirm to an ROV operator that two halves of the connector should be fully inserted and a connection established, with the point at which the indicator is set being dependent on the mounting employed, so that this may be tailored to a specific coupling type.

The engagement mechanism may further comprise a resilient nose cone on the front of the mounting for the second half of the coupler, which nose cone surrounds a second half of the coupler. This may act to shield the second part of a coupler from damage and aid insertion of the flying part into the fixed part and also avoid damage during the process of insertion.

The engagement mechanism as described above is particularly applicable for use in remotely connecting a subsea hose, tube or pipe to a fixed structure on the seabed.

The engagement mechanism is preferably arranged such that once a connection has been established between two halves of a coupling, subsequent rotation of the rotatable handle by an ROV in a second direction, opposite to the first direction, causes the second half the coupling, housed in the flying part, to withdraw from the first part of the coupling, housed in the fixed part of the engagement mechanism, and to subsequently cause the threaded member to unlock the flying part from the fixed part to permit the flying part to be axially withdrawn from the fixed part.

According to a second aspect of the present invention, there is provided an ROV mono-coupling comprising an engagement mechanism as described above and a coupling, wherein the second half of the coupling, housed in the flying part of the engagement mechanism, has a connector for a hose, tube or pipe, which connector extends in a direction having a radial component out of a hole or slot in a main body of the flying part and wherein a main body of the fixed part has an open ended slot extending axially to a distal end of the main body, which slot is arranged to receive the connector as the flying part is received into the fixed part. This ensures that no rotation of the hose, tube or pipe can occur.

According to a third aspect of the present invention, there is provided a coupling for a high pressure pneumatic or hydraulic line, the coupling comprising a female half and a male half arranged to be pushed into sealing engagement with each other by the engagement mechanism, wherein each half of the coupling has a passage which, when mounted in the engagement mechanism, extends in an axial direction, each passage comprising an axially aligned poppet valve for sealing with a respective seat in each passage, each poppet valve being urged against its seat by a respective spring and having a nose portion extending towards or out of the open end of each half of the coupling, which nose portions are arranged to engage with each other and open the poppet valves as the two halves of the coupling are pushed together.

One embodiment of the present invention will now be described, by way of example only, with reference to the following figures, of which: Figure 1 is a top perspective view of an engagement mechanism in accordance with the present invention; Figure 2 is a bottom perspective view of the engagement mechanism of Figure 1; Figure 3 is a top perspective view of the flying part of the engagement mechanism of Figures 1 and 2; Figure 4 is a bottom perspective view of the flying part of the engagement mechanism of Figure 3; Figure 5 is a side cross-section through the fixed part of the engagement mechanism and male coupling housed in the fixed part; Figure 6 is a side cross-section through the flying part of the engagement mechanism and the female coupling housed in the flying part; Figure 7 is a side cross-section of the fixed and flying parts of the engagement mechanism separated prior to insertion of the flying part into the fixed part; Figure 8 is a side cross-section corresponding to Figure 7, but showing the flying part inserted axially and docked in the fixed part of the engagement mechanism; Figure 9 is an enlargement of a section of Figure 8, showing the male and female couplings; Figure 10 is a side cross-section corresponding to Figure 7, but showing the engagement mechanism in a locked position, with the couplings opening; Figure 11 is an enlargement of a section of Figure 10 showing the male and female couplings; Figure 12 is a side cross-section corresponding to Figure 7, but showing the engagement mechanism fully mated and with the coupling open; and Figure 13 is an enlargement of a section of Figure 12 showing the male and female couplings.

Referring to Figures 1 and 2 these show an engagement mechanism in accordance with the present invention and indicated generally as 1. This comprises a fixed part 2 with a flying part 3 inserted therein and fully engaged with the fixed part.

Referring to Figures 3 and 4, these show the flying part 3 when separated from the fixed part 2. The flying part 3 comprising a main body 4 attached to a lifting bracket 5 which in turn is attached to a manoeuvring handle 6, the manoeuvring handle 6 is arranged to be held by a manipulator arm of an ROV. In this example, the manoeuvring handle has a fishtail shape, but other shapes are commonly employed. A further handle 7 is provided which is rotatable and which extends through the lifting bracket 5 into the main body 4. The rotatable handle 7 is also arranged to engage with a manipulator arm of an ROV having a rotatable drive unit, so that the rotatable drive unit may rotate the rotatable handle either in a clockwise direction or an anti-clockwise direction. Also evident in Figures 3 and 4 is a hose fitting 8 extending into the main body 4 of the flying part 3. As will be appreciated, particularly from Figure 2, the fitting 8 extending out of main body 4, as shown, will correctly rotationally align the flying part 3 of the engagement mechanism in the fixed part 2 by engaging in the slot 9 formed in a main body 10 of the fixed part 2.

Referring now to Figure 5, a cross section through the fixed part 2, this shows the various components of the fixed part and a male coupling (the fixed half of the coupling) 11 secured in the fixed part 2 of the engagement mechanism 1. The fixed part 2 comprises a main body 10 with a slot 9 running part way along one side and with a tapered opening. The main body 10 has an axial passage 12 forming a port for receiving the flying part 3 of the engagement mechanism. The passage 12 has a tapered opening 13, an annular recess 14, a first shoulder 15, a second shoulder 16, a first indicator 17 and a second indicator 18. Each indicator 17, 18 is biased inwardly by respective springs 19 and 20 and can be raised upwardly against the springs 19 and 20 by the flying part 2, as will be described below with reference to figures 7 to 13.

To a proximal end of the main body 10 there is attached a male coupling mount 21, which may be specific to the male coupling 11 to be used in the engagement mechanism 1. The male coupling 11 is inserted through the proximal end of the fixed coupling mount 21 and is held in place by castle nut 22, engaged with the distal end of the male coupling 11.

Referring now to Figure 6, a sectional view through the flying part 3 of the engagement mechanism, this shows both the various components of the flying part 3 and a female coupling 23 (the flying half of the coupling) mounted in the flying part 3 of the engagement mechanism.

The flying part 3 comprises a main body 4, to a proximal end of which is attached the lifting bracket 5 and manoeuvring handle 6, as previously described. Contained within the main body is a threaded shaft 24 connected to the rotatable handle 7. The threaded shaft 24 has an ACME fine thread is free to rotate with the rotatable handle 7, these being mounted in the main body 4 by glide ring 25 and thrust washers 26 and 27, which retain the threaded shaft 24 axially in position in the main body 4.

Threaded on to the threaded shaft 24 is cam member 28, which is prevented 15 from rotating in the main body 4, by guide pin 29 screwed into the cam member 28 and extending through slot 30 in the main body 4, as can be seen in Figure 4.

The cam member 28 has an annular camming surface 31 which acts against three dogs 32 (only one of which can be seen clearly in Figure 6) equally spaced about the cam member 28. As will be described subsequently, the cam member 28 can thus act to push the dogs 32 radially outward anchoring the flying part 3 in the fixed part 2.

Attached to the front of the cam member 28 is a female coupling mount 33, which may be specific to the female coupling 23 of the coupling to be used in the engagement mechanism 1. The female coupling 23 is held in place in the female coupling mount 33 by split ring 35 and castle nut 36, with the hose fitting 8 extending off the back of the female coupling 23. The provision of the female coupling mount 33 and the male coupling mount 21 (previously described) enables different types of coupling to be used with the engagement mechanism 1, with specific coupling mounts available for different coupling types.

To the front of the female coupling mount 33 there is attached, by grub screws 37, a bumper nose 38 of a resilient material. This surrounds the distal end of the female coupling 23 and protects it from damage. The bumper nose 38 also acts to guide the flying part of the coupling into the fixed part of the coupling, past the tapered opening 13, first shoulder 15 and second shoulder 16 within the axial passage 12 of the main body 10 of the fixed part 2, seen in Figure 5 and prevents these from being damaged.

The operation of the engagement mechanism 1 and of the coupling, comprising the male coupling 11 and female coupling 23, will now be described with reference to Figures 7 to 13.

Figure 7 shows the fixed part 2 mounted to a fixed subsea structure (not shown), ready to receive the flying part 3. The flying part 3 is axially aligned with the fixed part and correctly orientated, so that it may be moved forward in an axial direction by an ROV, not shown, into the fixed part 2. As the flying part 2 is received into the fixed part 2, the hose fitting 8 on the flying part 3 is guided by the tapered leading edge 12 into the slot 9 to the docked position shown in Figure 8. Here the hose fitting 8 will prevent rotation of the flying part 3 in the fixed part 2, as well as providing a conduit from the female coupling 23 to a hose, not shown.

With reference to Figure 8, the flying part 3 is now docked within the fixed part 2, with the leading edge of the main body 4 of the flying part 3 in contact with the first shoulder 15 of the fixed part 2, ensuring that the flying part 3 cannot be overly inserted into the fixed part 2, which could engage with the couplings 23 and 11 in an uncontrolled manner and damage the female and male couplings 23 and 11.

As the flying part 3 has been inserted into the fixed part 2, the base of the first indicator 17 has been raised, by travelling up chamfer 39 of the main body 4 (seen more clearly in the perspective view of Figure 3) until it has reached annular groove 40, where spring 19 has urged it back down inwardly to the position shown in Figure 8. This action of the spring 19 also acts to maintain the flying part 3 in the fully docked position, which is important because in this position the ROV will normally release the manoeuvring handle 6 to engage with the rotatable handle and thus the spring prevents the flying part being accidentally dislodged at this stage.

The exposed head of the indicator 17 has two coloured bands visible to the ROV operator through a camera of the ROV. On insertion, a first coloured band is apparent and then a second coloured band below the first, until the flying part 3 reaches the position shown in Figure 8, where indicator 17 drops back down so that only one band is visible. This indicates to the ROV operator that the flying part 3 is fully inserted. This can be doubled checked by at the same time noting that the second indicator 18 is partly raised. Only in the docked position shown in Figure 8 can the two indicators 17 and 18 have this configuration.

As can be seen from the enlarged section of Figure 8, shown in Figure 9, in the docked position of Figure 8 the male coupling 11 and female coupling 23 are still separated. At this point, the ROV operator commences rotation of rotatable handle 7 in a clockwise direction, rotating threaded shaft 24, which drives the cam member 28 forward in an axial direction to the position shown in Figure 10. Here the annular camming surface 31 has extended the three dogs 32 outwardly of the main body 4 of the flying part 3, so that they engage with the main body 10 of fixed part 2, thus locking the main body 4 of the flying part axially in position in the main body 10 of the fixed part.

Movement of the cam member 28 forward in an axial direction to the position shown in Figure 10, also moves the female coupling mount 33 and female coupling 23 forward in the axial direction, together with the with chamfer 41, most clearly visible in Figure 3. The forward movement of the chamfer 41 raises the second indicator 18 to a maximum position, seen in Figure 10, where two coloured bands are visible to the ROV operator, indicating that the female coupling mount 33 is about to reach the limit of its forward travel. At this point, as can be most clearly seen from the enlarged section of Figure 10, shown in Figure 11, the male coupling 11 has been partly received in female coupling 23, with the front portion of the male coupling 11 being inserted into the seals 42 in the female coupling 23.

Referring to Figure 11, here the detail of both the male coupling 11 and female coupling 23 can be seen. The male coupling 11, comprises a main body 45 with an axial passage 44 defining a seat 47 against which a poppet valve 48 is held in a closed position by spring 49 and any pressure in the passage 44. The poppet valve 48 has a forward projecting nose 50.

The female coupling 23 similarly comprises a main body 51 having an axial passage 46 defining a seat 52, against which a poppet valve 53, with a forward projecting nose 55, is held in a closed position by a spring 54 and any pressure in the passage 46.

At the position shown in Figure 11, the nose 50 of the poppet valve 48 of the male coupling 11 has come into contact with the nose 55 of the poppet valve 53 of the female coupling 23, but neither poppet valve has been displaced out of contact with its respective seat 47, 52. The ROV continues to rotate the handle 7 in a clockwise direction until the handle has been rotated approximately ten times, which is counted by the ROV, at which point the female coupling mount 33 reaches the position shown in figures 12 and 13, Figure 13 being an enlarged section of Figure 12. Here, an annular stepped edge 56 of the female coupling mount 33 (most clearly seen in Figure 3) has come into contact with the second inward shoulder 16 of the main body 10 of the fixed part 2, preventing further forward movement of the female coupling mount 33 in the fixed part of the engagement mechanism. Furthermore, the cam member 28 retaining the dogs 32 in the radially extended position shown in Figure 12 prevents the main body 4 of the flying part 3 from reversing out of the main body 10 of the fixed part 2, thus massively increasing the torque load experienced by the ROV rotating the handle 7, exceeding a preset torque threshold of 200Nm, terminating the rotating action and indicating to the ROV operator that the coupling 11, 23 has been fully mated and the operation is complete. This can be confirmed by ROV operator observing the indicators 17 and 18, where indicator 18 has been urged by spring 20 radially inwardly so that only a single colour band is visible and thus a single coloured band is now be visible to the ROV operator on both of the indicators 17 and 18, indicating that the operation is complete.

With reference to Figure 13, it is seen that the continued advancement of the male coupling 11 into the female coupling 23 has caused the poppet valves 48 and 53 to both be displaced from their respective seats 47 and 52, permitting fluid or gas to pass along the axial passages 44, 46 to or from the hose fitting 8 and the attached hose (not shown). Once the coupling has been opened, it that the action of the springs 49 and 54 will act to centralise the two poppet valves 48 and 53 in the positions shown in Figure 13 maximising flow through passages 44 and 46.

When it is desired to disconnect the engagement mechanism 1 and the coupling 11, 23 housed therein, an ROV engages with the flying part 13 by engaging both manoeuvring handle 6 and the rotatable handle 7 and commencing anti-clockwise rotation of the handle 7. This will initially wind back the female coupling 23 to the position shown in Figures 10 and 11, where the poppet valves 48 and 53 return into engagement with the respective seats 47 and 52, closing respective axial passages 44 and 46. At this stage the two main bodies 4 and 10 of the two parts of the engagement mechanism 1 are still locked together in axial position by dogs 32. Continued rotation of the handle 7 withdraws the cam member 28 to the position shown in Figure 8. However, the dogs 32 will not immediately retract radially inwardly as these are not biased to any position.

Furthermore, because there are three dogs 32, equally spaced about the cam member 28, at least one of the dogs 32 will, under the influence of gravity, remain into the annular groove 14 in the main body 3 of the fixed part 10 of the engagement mechanism 1. However, at this stage the torque experienced by the ROV rotating the handle 7 will rapidly increase and exceed a preset value of 200Nm, as the cam member 28 reaches its limit of travel, indicating that the flying part should be ready to be removed from the fixed part. This can be confirmed by the ROV operator observing that the second indicator 18 will now have been lowered such that no coloured bands are visible. The ROV operator can then axially withdraw the flying part 3 out of the fixed part 2, forcing one or more of the dogs 32 to be retracted, which dogs would have prevented accidental dislodgement of the flying part out of the fixed part should the ROV have, for any reason become detached from the flying part 3 prior to pulling it out the fixed part 2.

Although one embodiment of the present invention has been described by way of example only, it will be appreciated that many variations and modifications may be made which may fall within the scope of the present invention as defined by the following claims.

Claims

Claims 1. An engagement mechanism for a remotely operated vehicle (ROV) mono-coupling, which engagement mechanism is arranged to be operated by an ROV 5 and to receive and house two halves of a coupling, to form an ROV mono-coupling, the engagement mechanism comprising: a fixed part arranged to be connected to a fixed structure and to house a first half of the coupling; and a flying part, arranged to be connected to a hose, tube or pipe and to house a second half of the coupling, wherein: the fixed part of the engagement mechanism comprises a port in which the flying pad may be docked; the flying part of the engagement mechanism comprises a rotatable handle to be rotated by an ROV; the flying part of the engagement mechanism comprises a threaded member rotated by the rotatable handle; and wherein, once the flying part of the engagement mechanism has been docked in the port of the fixed part, rotation of the rotatable handle by the ROV in a first direction causes the threaded member to first lock the flying part in the fixed part, with continued rotation of the threaded member in the first direction subsequently causing a second half of the coupling housed in the flying part of the engagement mechanism to establish a connection with the first half of a coupling housed in the fixed part of the engagement mechanism.
2. An engagement mechanism as claimed in Claim 1 wherein the flying part is arranged to be inserted axially into the port to a predetermined position, prior to the rotatable handle being rotated by the ROV to lock the flying part in the fixed part.
3. An engagement mechanism as claimed in Claim 2 comprising a visual indicator to indicate when the flying part has been inserted into the fixed part to the predetermined position.
4 An engagement mechanism as claimed in Claim 2 or 3 wherein the flying part comprises a main body having an engagement surface arranged to contact an engagement surface of a main body of the fixed part, to form a stop and limit insertion of the main body of the flying part into the main body of the fixed part.
5. An engagement mechanism as claimed in Claim 4 wherein the main body of the of the flying part is prevented from rotating in the main body of the fixed part.
6. An engagement mechanism as claimed in Claim 5 wherein the flying part further comprises a carrier for the second half of the coupling, the carrier being threaded onto the threaded shaft, which carrier can move axially forward on the shaft as the shaft is rotated in a first axial direction and backwards on the shaft as the shaft is rotated in a second axial direction opposite to the first direction, wherein rotation of the handle in the first direction causes the carrier to move forward urging a locking device in the main body of the flying part to be displaced radially outward from the main body of the flying part to engage with the main body of the fixed part, to lock the two parts together in the axial direction, prior to continued rotation of the handle and continued forward movement of the carrier pushing the second half of the coupling into engagement with the first half of the coupling.
7. An engagement mechanism as claimed in Claim 6 wherein the flying part comprises a mounting for the second half of the coupler, which mounting is secured to the carrier and is interchangeable depending on the type of coupling 25 housed in the engagement mechanism.
8. An engagement mechanism as claimed in Claim 7 wherein the fixed part comprises a mounting for the first half of the coupler, which is interchangeable depending on the type of coupling housed in the engagement mechanism.
9. An engagement mechanism as claimed in Claim 7 or 8 wherein the mounting for the second half of the coupler comprises an engagement surface arranged to contact an engagement surface of the main body of the fixed part, to form a second stop that limits further forward travel of the mounting for the second half of the coupler.
10. An engagement mechanism as claimed in Claim 9 comprising a visual indicator to indicate when the mounting for the second half of the coupler has reached the second stop.
11. An engagement mechanism as claimed in Claim 7, 8, 9 or 10 further comprising a resilient nose cone on the front of the mounting for the second half of the coupler, which nose cone surrounds a second half of the coupler
12. An engagement mechanism as claimed in any proceeding claim for use in connecting a subsea hose, tube or pipe to a fixed structure on the seabed. 15
13. An engagement mechanism as claimed in any one of claims 6 to 12, wherein: the locking device comprises one or more dogs which may extend through apertures in a main body of the flying part to engage with the fixed part; as the carrier first moves axially forward, the one or more cammed surfaces act to push the one or more dogs radially outward so that they extend through the apertures in the main body and engage with the fixed part; and the one or more dogs are retained in the extended radially outward position by a surface or surfaces of the carrier during the continued forward movement of the carrier.
14. An engagement mechanism as claimed in any preceding claim wherein, once a connection has been established between two halves of a coupling, subsequent rotation of the rotatable handle by an ROV in a second direction, opposite to the first direction, causes the second half the coupling, housed in the flying part, to withdraw from the first part of the coupling, housed in the fixed part of the engagement mechanism, and to subsequently cause the threaded member to unlock the flying part from the fixed part to permit the flying part to be axially withdrawn from the fixed part.
15. An engagement mechanism as claimed in any preceding claim further comprising biasing means which acts to retain the flying part of the engagement mechanism docked in the port of the fixed part, prior to the flying part being locked in the fixed part.
16. An ROV mono-coupling comprising an engagement mechanism as claimed in any one of claims 2 to 15 and a coupling, wherein the second half of the coupling, housed in the flying part of the engagement mechanism, has a connector for a hose, tube or pipe, which connector extends in a direction having a radial component out of a hole or slot in a main body of the flying part and wherein a main body of the fixed part has an open ended slot extending axially to a distal end of the main body, which slot is arranged to receive the connector as the flying part is received into the fixed part.
17. An ROV mono-coupling comprising an engagement mechanism as claimed in any one of claims 2 to 15 and a coupling for a high pressure pneumatic or hydraulic line, the coupling comprising a female half and a male half arranged to be pushed into sealing engagement with each other by the engagement mechanism and wherein each half of the coupling has a passage which when mounted in the engagement mechanism extends in an axial direction, each passage comprising an axially aligned poppet valve for sealing with a respective seat in each passage, each poppet valve being urged against its seat by a respective spring and having a nose portion extending towards or out of the open end of each half of the coupling, which nose portions are arranged to engage with each other and open the poppet valves as the two halves of the coupling are pushed together.