GB2178101A

GB2178101A - Improvements in and relating to connector assemblies

Info

Publication number: GB2178101A
Application number: GB08615593A
Authority: GB
Inventors: Anthony John Asbury; John Drummond Mcgugan
Original assignee: Hunting Oilfield Services Ltd
Current assignee: Hunting Oilfield Services Ltd
Priority date: 1985-07-03
Filing date: 1986-06-26
Publication date: 1987-02-04
Also published as: GB2178101B; GB8615593D0

Abstract

A connector for connecting members in tension comprises a first body 2 and a second body 3, each for connection to a member. The first body 2 is provided with a generally cylindrical receptacle for receiving the second body 3 and the bodies are provided with radially extending projections 5, 14 which have axially directed shoulders 5a, 14a which in use are brought into alignment and abutment to prevent axial disengagement of the bodies. The second body 3 is received in the generally cylindrical receptacle of the first body 2, and upon tensioning of the connector these shoulders 5a, 14a are brought into axial abutment to prevent disengagement of the bodies. The first body 2 is provided with radially inwardly extending keys 7, which co-operate with key-ways 15 provided on the second body 3. As the second body 3 is moved relatively axially into the first body 2, the keys 7 are received in the key-ways 15 to cause any required initial relative rotation between the bodies to allow the projections 14 to pass between the projections 5 and to relatively rotate the bodies to axially align the shoulders 5a, 14a which on tensioning of the connector are brought into abutment. <IMAGE>

Description

SPECIFICATION Improvements in and relating to connector assemblies The present invention relates to a connector assembly for connecting members which in use are maintained in tension, such for example as a tendon string of a tether system for a tethered leg platform, and an anchor template.

According to the present invention there is provided a connector for connecting members which are in use maintained in tension, comprising a first body and a second body each connected or for connection to a said member, the first body providing a generally cylindrical receptable for receiving the second body, the bodies being provided with radially extending projections having axially directed shoulders which, in use of the connector, are brought into axial alignment and abutment to prevent axial disengagement of the bodies, the projections being arranged so that, in at least one relative angular position of the bodies, as the second body is moved relatively axially into the receptacle of the first body, the or each projection of the first body passes the or each projection of the second body, wherein one of the bodies is provided with guide means and the other body is provided with a boss for co-operation with the guide means at least on further relative axial movement of the bodies to rotate one of the bodies relative to the other body to axially align the projections of the bodies to allow the shoulders thereof to be brought into abutment.

The boss may be arranged to engage the guide means before the projections on the bodies come together to ensure that the bodies are in the or one of the said relative angular positions of the bodies to permit the or each projection on one body to pass the or each projection on the other body.

The guide means may comprise a first part for guiding the key during engagement of the bodies and a second part for guiding the key during disengagement of the bodies, guide means being arranged so that the bodies rotate relative to each other in the same overall direction during both engagement and disengagement.

Where the members connected to the bodies are not able to rotate relative to each other during assembly of the bodies, one of the bodies may be connected to its member through means permitting relative rotation between that body and its member during assembly.

The means permitting relative rotation may comprise a third body coaxial with the one body and axially movable relative thereto between a first position in which the bodies can rotate relative to each other and a second position which the bodies assume in use. Preferably the bodies have co-operating frustoconical surfaces which are in engagement in the second position.

Further features and advantages of the present invention will become apparent from the following description of an embodiment thereof, given by way of example only, with reference to the accompanying drawings, in which: Figure 1 is an axial section through an embodiment of connector assembly according to the present invention; Figure 2 is a section perpendicular to the axis through the connector assembly of Figure 1 during a stage in connection; Figure 3 is a developed view of part of the surface of one of the bodies of the connector assembly of figure 1; and Figure 4 is an axial section through an assembly optionally associated with the connector assembly of Figure 1.

The connector assembly shown in Figures 1 to 3 is intended for connection of a tendon string, which in use is maintained in tension, to an anchor template 1 of a tether system for a tethered leg platform.

The connector assembly comprises a first body 1 which, in use, is welded or otherwise fixed to the anchor template 1 which is installed on the sea bed, and a second body 3 which, in use, is connected to the tendon string.

The first body 2 provides a generally cylindrical receptacle 2a for the second body, which receptacle may be closed at its lower end. At the upper end, the body 2 is provided with a generally frusto-conical guide ring 4 surrounding the upper end and for guiding the second body into the receptacle, and the region of the upper end is provided with regularly spaced axially extending radially inwardly extending projections or splines 5 each of which provides at its Tower end a shoulder 5a. As shown in Figure 2, in this particular embodiment four splines are provided equally angularly spaced around the circumference of the receptacle and each subtending an angle which is approximately equal to the angle subtended by the space between the splines.It will however be appreciated that the number of splines provided may be varied depending on the particular circumstances and design of the connector assembly.

Below the splines 5, a corresponding number of radially inwardly projecting bosses or keys 7 are provided. The keys 7 may be fixed to the wall of the body 2 or, as shown, may be radially outwardly retractable. As shown on the left hand side of Figure 1, the key 7 has an enlarged head 8 which is located in a recess in the outer wall of the body 2 and is biased outwardly by springs 9. A release pin 10 holds the key 7 in its radially inner position, the pin 10 being mounted in a housing 11 surrounding the key head and fixed to the outer wall of the body 2. If required, the pin 10 can be withdrawn by axial upward movement, using an appropriate tool which is lowered from the surface of the water, to release the key 7 which will then move outwardly under the action of the springs 9.

The closed lower end of the body 2 may be provided with an axial opening 12 for a guide wire attached to and for guiding the second body 3 into the first body 2.

The second body 3 has an outer generally cylindrical surface which, adjacent the upper end is provided with splines 14 corresponding to the splines 5 of the first body and which provide axially directed shoulders 1 4a for abutment with the shoulders 5a provided by the splines on the first body 2.

Splines 14 are dimensioned and arranged relative to splines 5 so that, during engagement of the bodies 2,3, as body 3 is moved into body 2, splines 14 will pass between (as shown in Figure 2) and beyond splines 5. Rotation of body 3 relative to body 2 will then bring the splines 14 into axial alignment with splines 5 and tensioning of the tendon string attached to body 3 will bring the bodies 2,3 into their final position with shoulders 5a,14a in abutment.

Below the splines 14, the body 3 is provided with guide means or key-ways 15 for receiving the keys 7 of the first body and which are more clearly shown in Figure 3. The key-ways are shaped to cause the required rotation of the second body 3 relative to the first body 2 as the bodies are assembled to bring them into the required relative orientation for abutment of the shoulders 5a,14a on the splines. Co-operation between the keys and keyways also causes any required initial rotation of body 3 relative to body 2 to bring the splines 14 into a position such that they can pass between the splines 5 on body 2.

As the bodies 2,3 are moved axially together, and before the splines 5,14 interengage, each key 7 enters a first guide portion 15a of the respective key-way 15, which provides converging walls 15b. If the splines 14 are not in the required position for interengagement with the splines 5, each key 7 will contact one of the walls 15b to cause body 3 to rotate as the keys move along the walls 15b, to bring the keys to generally axial portions 15c. At this point the splines 14,5 will have the required orientation and during passage of the keys along portions 15c, splines 15 will pass between and through splines 5.

At the point that the splines 14 are clear of splines 5, the keys contact and move along inclined walls 15d causing body 3 to rotate to move the splines 14 to a position in partial alignment with splines 5. When the keys reach points 15e at the limit of downward movement of body 3 relative to body 2 (shown on the left-hand side of Figure 1), body 3 is then lifted. The keys then run along inclined walls 15f causing body 3 to rotate slightly in the reverse direction and then run along walls 1 5g causing further rotation of body 3 in the forward direction. Finally the keys assume positions 15h in which each is located in a recess 15k. At this point body 3 has rotated to bring splines 14 into full alignment with splines 5 and shoulders 5a,14a are in abutment (shown on the right-hand side of Figure 1).Further angular movement of body 3 relative to body 2 is prevented by the lateral walls of each recess 15k and the recess is sufficiently deep that the respective key is not in contact with the base of the recess (which could prevent full abutment between shoulders 5a,14a).

For disengagement purposes, the key-ways are, in this embodiment, designed so that the overall relative direction of rotation on disengagement is the same as that for engagement.

It will of course be appreciated that the keyways could be arranged so that the path followed by each key is the reverse of that for engagement. As shown, for disengagement, tension on the tendon string attached to body 3 is released and the body 3 moves downwardly relative to body 2, initially axially to release the keys from recesses 15k and bring them into contact with inclined walls 151 which causes partial rotation of the body 3 until the keys reaches positions 15m. At this point the body 3 is lifted and keys run along walls 15n causing reverse rotation of body 3 until the keys contact inclined walls 15p when the direction of rotation reverses and continues in the forward direction to bring the keys into the axial portions 15c of the adjacent key-ways.At this point the splines 5,14 are in a relative position that splines 14 can move between splines 5 to free the body 3 from body 2 to enable it to be withdrawn to the surface.

Where the suspension of the tendon string does not of itself permit rotation of the string, means may be provided between the tendon string and body 3 permitting body 3 to rotate relative to the tendon string at least during engagement and disengagement of the connector. In the embodiment shown in Figure 1, these means are incorporated in body 3.

As shown, body 3 is generally annular and is provided with an end cap 3a closing the end of the hollow in the body 3 and which is provided with a ring 16 for attachment to a guide wire. A third body 17 is received within body 3 and it is body 17 which is connected to the tendon string. Body 17 is axially movable relative to body 3 between a first lower position (shown on the left-hand side of Figure 1) and a second upper position (shown on the right-hand side of Figure 1) and is arranged to be rotatable relative to body 3 in its first position and in an intermediate position between the first and second positions, and may be non-rotatable relative to body 3 in its second position.

The periphery of body 17 is provided with at least one frusto-conical portion and the inner surface of body 3 is provided with a corresponding frusto-conical portion, both of which taper upwardly, so that when body 17 is tensioned the frusto-conical portions come into engagement to prevent relative axial deflection between bodies 3,17. As shown, the circumferential surface of body 17 is provided with two frusto-conical portions 18,19, for example each with a cone angle of the order of 6 , and which are spaced apart by a cylindrical portion 20, a further cylindrical portion 21 being provided adjacent the lower end of body 17 and the corresponding surface of body 3.The cylindrical portions of body 17 have diameters which are slightly smaller than those of the corresponding portions of body 3 to ensure that these portions do not come into contact and interfere with full engagement of the frusto-conical portions 18,19.

During initial engagement of the members 2,3 while member 3 is being lowered into member 2, body 17 assumes its lower position with the end of the body bearing on a thrust plate 22 provided on cap 3a and in this position body 3 is rotatable relative to body 17. During the second part of engagement of bodies 2,3 in which the tendon string is tensioned to pull body 3 upwardly, the tension is primarily applied to body 17 which moves upwardly. In this stage, less than full tension is applied to body 17 and the two bodies are held apart permitting continued rotation between body 3 and body 17 by springs 23 located between a shoulder 24 on body 3 and a thrust washer 26 abutting shoulder 25 and permitting continued rotation.Finally the full tension is exerted on the tendon string which overcomes the action of springs 23 to bring the frusto-conical surfaces 18,19 into full engagement and prevent relative axial deflection between the bodies 3,17, and may also frictionally prevent further relative rotation between the bodies 3,17.

For disengagement purposes, when the tension on the tendon string is released, body 1 7 should move downwardly relative to body 3 to free body 3 for rotation relative thereto. In the event that body 17 does not free itself automatically, it is provided with a central passage 27, communicating with the central passage in the tendon string, together with one or more radial ducts 28 opening into the region of one of the frusto-conical surface portions, as shown portion 19. In the event that body 17 does not free itself automatically from body 3, fluid under pressure can be passed down central passage 27 and along ducts 28 into the region of the frusto-conical surfaces to break the frictional engagement.

Seal assemblies 29 and 30 are provided at the ends of surfaces 18 to 21 to prevent penetration of water in use.

Where it is required to permit axial deflection or inclination of the tendon string about a horizontal axis relative to the connector assembly, the upper end of body 17 may be connected to or form one part 33 of a flexible Joint, for example as shown in Figure 4. The joint also comprises a second part 34 which is connected, e.g. by welding, to the tendon string. Parts 33 and 34 are provided with mating part hemispherical surfaces 35,36, one of which, as shown surface 36, is provided by the surface of a gimbal bearing 42 received in the end of part 34 which are held together under compression by a flexible thrust bearing 37 bearing on a collar 38 on the member 34 and a collar 39 fixed to an annular member 40 threaded onto the end of the other member 33. Where the members 33,34 are tubular with a central passage way, annular seal assemblies 41 may be provided between surfaces 35,36.

It will be appreciated that, while the invention has been described in relation to a connector for connecting a tendon string to an anchor template, the invention is equally applicable to the connection of other members which are to be maintained in tension. Equally it will be appreciated that the above described connector may be used in a different orientation. For example it may be inverted or could be used with its axis inclined to the vertical (eg horizontai). When used as above described or in any other -orientation, it will be understood that relative movements of the bodies 2,3 and 17 (when provided) away from each other (upward as described above) are caused by tensioning of the members connected to the bodies and relative movements of the bodies 2,3 towards each other (downward as described above) may be caused by gravity or by other suitable means, eg by ten sioning a wire line attached to ring 16 on body 3.

Claims

1. A connector for connecting members which are in use maintained in tension, comprising a first body and a second body each connected or for connection to a said member, the first body providing a generally cylindrical receptacle for receiving the second body, the bodies being provided with radially extending projections having axially directed shoulders which, in use of the connector, are brought into axial alignment and abutment to prevent axial disengagement of the bodies, the projections being arranged so that, in at least one relative angular position of the bodies, as the second body is moved relatively axially into the receptacle of the first body, the or each projection of the first body passes the or each projection of the second body, wherein one of the bodies is provided with guide means and the other body is provided with a boss for co-operation with the guide means at least on further relative axial movement of the bodies to rotate one of the bodies relative to the other body to axially align the projections of the bodies to allow the shoulders thereof to be brought into abutment.

2. A connector as claimed in Claim 1, wherein the guide means comprise a first part for guiding the boss during engagement of the bodies and a second part for guiding the boss during disengagement of the bodies.

3. A connector as claimed in Claim 2, wherein the guide means are arranged to cause relative axial movement of the bodies in the same overall direction during engagement and disengagement of the bodies. claims, wherein the guide means comprise a third part engageable by the boss as the bodies are moved together to position the bodies in the or one of the said relative angular positions thereof.

5. A connector as claimed in any one of the preceding claims, wherein the guide means include a portion in the form of a recess for receiving the boss when the shoulders are in axial alignment and which is shaped to prevent relative angular movement of the bodies when the shoulders are in axial abutment.

6. A connector as claimed in Claim 5, wherein when the boss is received in the recess, engagement between the boss and the recess does not interfere with axial abutment of the shoulders on the bodies.

7. A connector as claimed in any one of the preceding claims, comprising a plurality of bosses for engagement with the guide means, the bosses being circumferentially spaced apart around the other body.

8. A connector as claimed in any one of the preceding claims, wherein one of the bodies is connected or for connection to the respective one of said members by means permitting rotation of the one body relative to the said member at least during engagement of the bodies.

9. A connector as claimed in Claim 8, wherein the means permitting rotation of the one body relative to the said member comprises a third body coaxial with the one body, connected or for connection to the said member and axially movable relative to the one body between a first position in which the one body and the third body are rotatable relative to each other, and a second position in which the one body and the third body are axially fixed together and which the one body and the third body assume when the connector is in use.

10. A connector as claimed in Claim 9, wherein the one body and the third body have corresponding frusto-conical surfaces which, in the second position, are in engagement.

11. A connector as claimed in either Claim 9 or Claim 10, wherein the one body is the said second body which is annular, and the third body is received within the second body.

12. A connector as claimed in Claim 11, wherein the one body and the second body have co-operating frusto-conical surfaces, the apices of the cones of which are directed in the direction of the tension to be applied thereto in use.

13. A connector as claimed in any one of Claims 9 to 12, wherein means are provided for biasing the said one body and the third body towards the said first relative position thereof.

14. A connector as claimed in any one of the preceding claims, wherein means for permitting inclination of the connector relative to one of the said members is provided for connection between the respective body of the connector and the one member.

15. A connector as claimed in any of the preceding claims, wherein the or each boss is adapted to be radially retractable.

16. A connector substantially as herein described with reference to the accompanying drawings.