GB2205370A - Pipe connectors - Google Patents

Abstract

The present invention provides a connector (10) comprising retaining means (22), actuator means (60), follower means (82) and mechanical drive means (96 - 130). The actuator means (60) is arranged to be reciprocated hydraulically so as to operate the retaining means (22) and thereby releasably retain the connector (10) on a connection unit (12). The follower means (82) is connected to the actuator means (60) so as to reciprocate therewith. The mechanical drive means (96 - 130) is connected to the follower means (82) and is operable to retract the follower means (82) and the actuator means (60) so as to release the connector (10) from the connection unit (12). The drive means (96 - 130) is provided with means (84) for receiving a remotely operated tool and is arranged for actuation by the remotely operated tool. Preferably, the drive means (96 - 130) provides a lock-down facility and the interaction between the actuator means (60) and the retaining means (22) is such as to resist disengagement of the connector (10) from the connection unit (12) resulting from axial tension between the connector (10) and connection unit (12). <IMAGE>

Description

Title:- A CONNECTOR The present invention relates to v connector and. finds particular but non-limiting a:ppli#ation to sub-seaconnections between components of a fluid production system such as an oil or gas well.

There has been an increasing trend towards the use of hydraulically operated connectors for connecting sub-sea components of fluid production systems. In the event of failure of the hydraulic system i# is often necessary to send a diver to effect manual override of the connector. This involves considerable risk for the diver, incurs significant expense and is not feasible for some existing and many proposed deep water wells.

With a view to mitigating the above disadvantages, the present invention provides a connector comprising retaining means arranged to bereciprocated hydraulically so as to releasably retain the connector on a connection unit, comprist2y a follower connected to the retaining means so as to reciprocate therewith and mechanical drive means connected the follower and operable to retract the follower and retaining means so as to release the connector from the connection unit.

the drive means having means for receiving a remotely operated tool and being arranged for actuation by the remotely operated tool.

Preferably, the mechanical drive means is arranged so as to be actuable to lock the retaining means. when the connector has been latched onto the connection unit.

Advantageously, the follower is configured so as to enable the follower to be mechnically gripped externally of the connector and to be retracted by a direct pulling action in order to provide a last resort override of both the hydraulic system and the mechanical drive means.

An embodiment of the invention will now be described by way of example only and with reference to the accompanying drawing. in which: Figure 1. is a vertical section through a connector embodying the invention. and Figure 2 is an enlarged sectional view of the retaining ring shown in figure 1.

Figure 1 shows a connector 10 in a partial cut-away vertical section. As shown the connector 10 is just prior to final mating with and retention on a connection unit 12. which may be a well head or so-called tree connector. The connector 12 is in the form of a upstanding cylidrical tube having a rim 14 terminating its upper end. Rim 14 is formed by a circumferential groove 16 provided in the outer cylindrical surface of the tube. The upper and lower walls, 18 and 20 respectively. of groove 16 are inclined such that the width of the groove at the cylindrical surface is greater than the width of the base, 17. of the groove.

Connector 10 generally sitsPover the connection unit 12 and includes retaining means which seat in grooves 16 thereby latching the connector 10 to the connection unit 12.

The connector 10 includes a retaining member 22 which is in the form of a split ring. Split ring 22 has its inner periphery configurerd to complement the profile of groove 16. The internal periphery of split ring 22 consists of: upper inclined surface 24 (for abutment with surface 18 of groove 16), longitudinal face 26 (for abutment with the base 17 of groove 16) and lower inclined base 28 (for abutment with surface 20 of groove 16). The remaining periphery of split ring 22 includes a narrow annular upper surface 30, inclined bearing surface 32. an outer longitudinal face 34, a lower inclined outer face 36 and a narrow annular base 38.

Connector 10 has a main body 40 which has the general shape of a short cylinder with a stepped internal bore 42. The internal bore comprises an enlarged lower chamber 44 which receives the connection unit 12 and an upper chamber 46 intended to provide fluid communication between the internal bore of the connection unit 12 and an outlet 48 provided on connector 10. The lower end of chamber 46 is surrounded by a frusto-conical projection 50 which passes into the internal bore of the connection unit 12 and mates therewith. The connector body 40 is provided with a circumferential recess 52 extending radially outwards at the top of the lower central chamber 44. Recess 52 houses split-ring 22 which is seated on an anti-friction ring 54 located in a stepped portion at the lower inner edge of recess 52.An annular seal 56 is located above split-ring 22 and has an inwardly projecting upper rim 58 which seats on the upper surface of connection unit 12. when connector 10 is fully engaged with unit 12.

In its unbiased position, split-ring 22 has an internal diameter substantially equal to the external diameter of the upper cylindrical surface of connection unit 12.

With connector 10 seated on connection unit 12 splitring 22 is positioned slightly above groove 16. Ring 22 is then forced radially inwards so that surface 24 slides over surface 18. This has the effect of causing a small additional downward movement of connector 10 with a corresponding compression of the rim 58 of seal 56. With connector 10 fully latched on connection unit 12, the internal periphery of split ring 22 is fully seated in the complementary shape of groove 16 - thus retaining connector 10 on connection unit 12.

The described movement of split ring 22 is effected by a number of plunger segments 60, usually six. located in respective longitudinal slots 62 angularly spaced around connector 10. Slots 62 pass through the wall of the connector so as to communicate with recess 52. The plunger segments 60 are held in respective apertures in an annular sleeve 64 which slides in a recess 66 provided on the outer cylindrical surface of the connector body 40. A cover plate 68 closes the recess 66 so as to form an upper hydraulicchamber 70 above sleeve 64 and a lower hydraulic chamber 72 beneath slide 64. The lower inner edge 61 of each plunger segment 60 has a camber which initially contacts the upper outer inclined surface 32 of split ring 22.

With the connector 10 seated on connection unit 12 and hydraulic pressure supplied via supply line 74 to chamber 70, sleeve 64 is urged downwards. The plunger segments 60 are therefore also urged downwards and each surface 61 acts on and slides over surface 32. This action forces surface 24 of the split ring over surface 18 of groove 16 so that the split ring 22 starts to move into groove 16. Subsequently, surfaces 61 and 32 move out of contact and the inner longitudinal face of each plunger segment comes into contact with surface 34 of ring 22. As this occurs, the bottom surface 34 of ring 22 slides across the anti-friction ring 72 and ring 22 fully seats in groove 16. It will be noted that with the connector 10 fully latched to connection unit 12 there is a certain resistance to the plunger segments 60 being forced upwards by outward movement of ring 22.

This is a result of the line of contact between the two components being. in these circumstances, nearly parallel with the longitudinal axis of the connector and connection unit. Thus, it may not be necessary to maintain hydraulic pressure in chamber 70 in order to retain the connector in the latched position.

When it is desired to unlatch connector 10 from connection unit 12, hydraulic pressure is supplied to chamber 72 via supply line 76, the supply of hydraulic pressure to chamber 70 already having been removed.

Hydraulic pressure in chamber 72 forces the sleeve 64 and plunger segments 60 to move upwards thus allowing split ring 22 to spring out of groove 16 under its own self-bias.

A back-up hydraulic system is provided in order to enable unlatching of connector 10 from connection unit 12 in the event of failure in the hydraulic system associated with supply line 76. The back-up hydraulic system comprises an annular ring 78 normally seated at the bottom of recess 66. Should the back-up system be required, hydraulic pressure is supplied to the underside of ring 78 via a supply line 80. Ring 78 is thus forced upward where it contacts the bottom of sleeve 64 and subsequently forces sleeve 64 and plunger segment 60 upwards, thus unlatching the connector.

Supply lines 74,76 and 80 are only partially shown in Figure 1 for the sake of clarity of the drawing.

The connector 10 includes a mechanical drive means operable to provide an additional mechanism whereby the annular sleeve 64 and plunger segments 60 can be retracted, thus causing split ring 22 to spring out of groove 16 and thereby releasing connector 10 from connection unit 12. The mechanical drive means is arranged for actuation by a remotely operated tool which is lowered to the connector and coupled with the drive means, as and when necessary. Actuation of the drive means by a remotely operable tool advoids the necessity of having a diver descend to the well head to operate the drive means manually. Such an operation involves significant risk for the diver. is costly and is not feasible for deep water wells.The drive means comprises a number of followers 82. each attached to a respective plunger segment 60, and a drive gear arrangement which translates rotary actuation by the remotely operated tool into linear motion of the followers 82.

The drive gear arrangement includes at least one and preferably two actuator units 84 capable of receiving a remotely operated tool. Components of one actuator unit 84 are rotated by the remotely operated tool. in a manner to be described, and this rotary motion is transmitted to an annular gear wheel 86 which drives a number of drive units 88. Each drive unit 88 translates the rotary action of the annular gear wheel 86 in order to effect linear motion of a respective follower 82.

The followers 82 comprise respective rods 90 and each of the plunger segments 60 is provided with a respective spigot 92 which projects outwardly from the outer lateral face of each plunger segment. Each rod 90 is connected to the respective spigot 92 by a ring connector 94 which has the spigot 92 threadedly engaged with the central aperture thereof. Rod 90 of each follower threadedly engages an aperture in the upper surface of the ring connector 94 of the follower. The rod of the followers associated with the actuator units 84 are passive and simply pass through the centre of the unit. In contrast, the rod 90 of each follower 82 associated with a drive unit 88 is active. That is. the rod 90 is driven along its longitudinal axis by the drive unit 88.

Actuator unit 84 comprises a drive spindle 96, provided with drive splines 98 at its upper end, and has a drive wheel 100 connected adjacent its lower end. Drive spindle 96 is supported by a support cylinder 102 which has a central aperture through which drive spindle 96 passes. A rim 104 on the drive spindle seats on the upper annular surface of support cylinder 102 which acts as a beaTing surface for rotation of drive spindle 96.

The outer surface of support cylinder 102 is configured to receive and retain the outer housing of a remotely operated tool. This configuration includes a circumferential groove 106 into which a retaining member of the tool is latched and also includes anti-rotation splines 108 which prevent the tool housing from rotating as the tool drives spindle 96 via splines 98.

Rod 90 extends through a central bore in spindle 96 and projects above the upper end of the spindle. Rod 90 moves freely in the longitudinal direction through the centre of the spindle and contacts an indicator mechanism within the remotely operated tool. when the tool is latched onto the actuator unit 84. Thus as follower 82 reciprocates with movement of sleeve 64 rod 90 operates the indicator mechanism within the tool, thereby enabling remote sensing of the position of retaining ring 22. This enables determination of whether or not the connector 10 is fully latched to the connection unit 12.

The teeth of drive wheel 100 mesh with the teeth of annular gear wheel 86 which are provided on the inner circumference thereof. Drive wheel 100 and annular gear wheel 86 are housed beneath a cover 110 which is seated on the upper surface of body 40 of the connector 10.

The annular gear wheel 86 is seated in upper and lower bearings located in respective annular recesses, one provided in the surface of the body 40 and the other provided in the underside of cover 110.

In drive unit 88 the annular gear wheel 86 meshes with and drives a drive cylinder 112. The drive cylinder 112 has a step in its outer surface thus providing an upper drive cylinder 114 of reduced external diameter. Upper drive cylinder 114 rotates within an aperture passing through cover 110. Drive cylinder 112 is supported on an annular bearing (not shown) seated on the upper surface of the body 40. A central bore passes through drive cylinder 112 and the bore is enlarged within upper cylinder 114 and also adjacent the bottom face of the cylinder 112. Rod 90 of the follower 82 passes through the centre of drive cylinder 112 and the rod has two collar rigidly attached thereto.The upper collar 116 carries an external thread and the lower collar 118 is provided with longitudinal splie. The splined collar 118 passes through an anti-rotation g.ng 120 which is bolted to the upper surface of body 40 and housed within the enlarged bore provided at the lower end of the central bore in drive cylinder 112. Splined collar 118 and anti-rotation ring 120 prevent rotation of rod 90 while allowing reciprocating movement thereof.

The inner cylinder wall which defines the enlarged bore within upper drive cylinder 114 is provided with longitudinal splines 122 which project radially inwards for a relatively short distance compared with the radius of the enlarged bore. These splines 122 engage a complementary configuration provided in the outer cylinder wall of a nut 124 which is received within the enlarged internal bore of upper drive cylinder 114. Nut 124 has a threaded central aperture such that the nut is threadedly engaged with threaded collar 116 on rod 90.

The top of the drive cylinder 112 is closed by a cap 126 which seats over the top of upper !cylinder 114 and which has a central seal 128 through Which the rod 90 passes.

Cap 126 is retained on upper cyirnder 114 by a plurality of shear pins 130 such that thewcawp rotates together with the drive cylinder. Each rota. sO associated with a drive unit 88 is terminated beyond the respective cap 126 by an enlarged head 132.

Use and operation of the drive arrangement will now be explained in more detail.

During normal operation of the connector, as described above, sleeve 63 is hydraulically operated so as to latch or unlatch the connector via retaining ring 22.

Normally, the connector 10 is located and retained on connection unit 12 with sleeve 64 positioned at the lower limit of its travel in recess 66. As mentioned above. there is resistance to upward movement of plunger segments 60 and sleeve 64 even in the absence of maintained hydraulic pressure in chamber 70. due to the near vertical interface between the plunger segments 60 and the retaining ring 22. It is clearly undesirable to have to maintain hydraulic pressure within chamber 70 at all times when the connector is retained on the connection unit since this represents effectively the whole of the working life of the connector. However, the resistance to outward motion of split-ring 22 offered by the near vertical interface with plunger segments 60 is insufficient to provide reliable retention of the connector on the connection unit.Significant forces tending to disengage the connector from the connection unit can be generated in the pipe line attached to the connector by many different causes. Thus it is desirable to provide some form of mechanical locking so as to ensure that the sleeve 64 remains at its lower limit of travel. That is, to ensure that retention ring 22 remains in grooves 16. Such a mechanical locking facility is available via the drive arrangement, in the following manner.

Once sleeve 64 has been moved hydraulically to the lower limit of its travel, a remotely operated tool is lowered into position on an actuator 84. The remotely operated tool rotates drive spindle 96 and thus rotates annular gear wheel 86 via drive wheel 100. This in turn rotates drive cylinder 112 which, via splines 122, results in rotation of nut 124. Rod 90 is held against rotation and rotation of nut 124 therefore causes the nut to progress along threaded collar 116. The direction of rotation and number of revolutions imparted to drive spindle 96 by the remotely operated tool is pre-calculated to cause nut 124 to rise within the enlarged chamber of upper drive cylinder 114 until the nut 124 abuts against cap 126. In this position, nut 124 locks follower 82 and therefore sleeve 64 against upward movement. Any upward movement is resisted by contact between nut 124 and cap 126.Once this locking operation has been completed the remotely operated tool is withdrawn.

If it is desired to unlock the arrangement, the tool is re-applied and nut 124 is lowered back to its original position. However, in the event of emergency release of the locking mechanism being required, either for the sake of speed or because of a fault in the drive.

mechanism, shear pins 130 are designed to shear upon application of a force slightly less than that which can be applied by supplying full hydraulic pressure via supply line 76, or via supply lines 76 and 80 in combination.

The main function of the mechanical drive arrangement is to provide a mechanical override to operate the retaining means in the event of failure of the hydraulic system. Assuming that the connector is retained on the connection unit and that the hydraulic system has failed with the subsequent requirement to disengage the connector from the connection unit, the following operation can be applied.

A remotely operated tool is lowered onto and secured with actuator unit 84. The tool rotates drive spindle 96 which, in the above described manner, causes rotation of drive cylinder 112 with resultant longitudinal movement of nut 124. However. in these circumstances the sense of rotation is such as to cause nut 124 to move down threaded collar 116 until the under surface of the nut contacts the step in the internal bore of cylinder 112 defined by the base of the enlarged bore of upper drive cylinder 114.Nut 124 seats in the bottom of the enlarged bore and contitrued rotation of drive cylinder 112 causes the rod 90 to be pulled linearly upwards, rotation of rod 90 being;revented by splines 118 and anti-rotation ring 120. rotation of drive cylinder 112 thus causes upward movement of the follower 82, sleeve 64 and plunger segments 60 - enabling retention ring 22 to ease out of groove 16 thereby releasing the connector. It is to be noted that when actuator unit 84 is actuated by the remotely operated tool each of the drive units 88 round the connector are operated simultaneously. In addition, the follower 82 associated with the active actuator unit 84 moves upwards as sleeve 64 is retracted. thus enabling the remotely operated tool to monitor the retraction of sleeve 64.

In the unlikely event of complete failure of both the hydraulic and mechanical release systems, grapples can be lowered to grasp the heads 132 of the followers associated with the drive units. This enables the followers 82 to be pulled directly sovas to release the retaining means. Such last resort- release of the retaining means may or may not involve shearing of the shear pins 130, depending upon thexposition of nuts 124. One embodiment of the invention has been described with reference to the accompanying drawing. Various modifications will be readily apparent to those skilled in the art and such modifications are included in the scope of the present invention.

Claims (13)

CLAIMS:

1. A connector comprising retaining means, actuator means arranged to be reciprocated hydraulically so as to operate the retaining means and thereby releasably retain the connector on a connection unit, follower means connected to the actuator means so as to reciprocate therewith, and mechanical drive means connected to the follower means and operable to retract the follower means and actuator means so as to release the connector from the connection unit, the drive means having means for receiving a remotely operated tool and being arranged for actuation by the remotely operated tool.

2. A connector as claimed in claim 1, wherein the retaining means comprises a split-ring and the actuator means comprises a plurality of plungers arranged to be reciprocated perpendicularly with respect to the plane of the split-ring.

3. A connector as claimed in claim 2, comprising a hydraulically operated annular sleeve which surrounds the split ring and which is arranged to cause the plungers to reciprocate.

4. A connector as claimed in claim 3, comprising a hydraulically operated annular ring arranged to effect reciprocation of the annular sleeve in the event of failure of the hydraulic system associated with the annular sleeve.

5. A connector as claimed in claim 2 or 3, wherein the follower means comprises a plurality of shafts each connected to a respective plunger.

6. A connector as claimed in claim 5, wherein the mechanical drive means comprises a rotatable element, rotation of which is arranged to effect reciprocation of a number of the shafts by way of respective drive mechanisms.

7. A connector as claimed in claim 6, wherein each drive mechanism comprises a nut threadedly engaged with the shaft and constrained to rotate with a driven element which is contacted by the said rotatable element.

8. A connector as claimed in claim 7, wherein the drive mechanism comprises an abutment against which the nut may be brought to bear so as to lock the shaft and hence the actuator and retaining means.

9. A connector as claimed in any of claims S to 8, wherein each of the said number of shafts extend beyond their respective drive mechanism and are terminated by a grappel receiving configuration.

10. A connector as claimed in claim 6, wherein the said rotatable element is an annular cog.

11. A connector as claimed in any of claims 2 to 10, wherein the follower means associated with one plunger is not driven but is instead connected to an elongate element which indicates the relevant position of the plunger.

12. A connector as claimed in any of claims 2 to 11, wherein the plungers and the split-ring are configured such that with the connector fully retained on the connection unit the mutually contacting surfaces of the split-ring and plungers are substantially aligned with the axis of reciprocation of the plungers.

13. A connector substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.