GB2532064A

GB2532064A - Connection device

Info

Publication number: GB2532064A
Application number: GB1419871.7A
Authority: GB
Inventors: James Bowles Christopher
Original assignee: Individual
Current assignee: Individual
Priority date: 2014-11-07
Filing date: 2014-11-07
Publication date: 2016-05-11
Also published as: GB201419871D0

Abstract

A connection assembly, for connecting a downhole tool to coiled tubing, having a gripper 2 to pass over a tube 3 in a first configuration, and to grip the outside of the tube in a second configuration when compressed. The assembly comprising a top sub-assembly 1 with an aperture to allow it to be passed over the tube 3 and a gripper 2; a seal housing 16 having an aperture to allow it to be passed over the end of the tube and an abutment face for forming a seal against a face of a sealing ring 17, to seal between the abutment face and the end face of the tube; an initiator ring 18 formed of relatively deformable material and interposed between the seal ring housing and the gripper; a seal housing carrier 29 to receive the seal housing from one end only, and to allow access to a face of said seal housing from the other end. The top sub-assembly and seal housing carrier are adapted to be releasably held together to trap the gripper.

Description

CONNECTION DEVICE

Field of the Invention

The invention relates to a connection device suitable for connecting down-hole tools to tubes, especially for use in the drilling industry, for example the oil and gas industry. More particularly, the invention relates to external grapple connectors. The invention also relates to methods for joining a connection device to a tube.

Background and Prior Art

This invention is an improvement on the connection assembly described in the inventor's earlier patent application W02014/033072. That application described the Is context of the invention, which remains unchanged, and is repeated here for completeness: In the drilling industry, and in particular for oil and gas, underground operations are often carried out by affixing tools and the like to the end of tubes, through which material can flow. The tubes used are often so-called "coil tubing" usually made of steel, and that are stored as a coil of material that can be uncoiled for use. In order to attach such tools to the end of the tube, a connector is required. Two forms of connector are common* those that connect to the inside diameter of the tube (Inline Connectors) and those that connect to the outside diameter of the tube (Outline Connectors). Inline connectors have the advantage that there is no increase in the outside diameter of the coil tubing by use of the connector, but with the disadvantage that the bore is restricted, leading to a smaller flow through the tube once the connector is in place. Outline (or grapple) connectors have the advantage that they do not restrict the bore of the tube following connection, although the increased outside diameter of the assembly can restrict their use in some circumstances. The present invention relates only to external/outline grapple connectors.

Such grapple connectors are fixed on to the outside diameter of the coil tubing at the end of the coil tubing reel and are used to attach and run (deploy) what is known in the industry as a Bottom Hole Assembly (BHA), which is a screwed-together combination of pressure-operated tools, such as: jarring subs, hammers, back pressure valves, and milling bits, (called a tool string). This is used to carry out live oil or gas well intervention work, e.g. descaling, fishing out of well trapped/broken equipment, and milling/drilling operations.

Existing coil tubing grapple connectors typically consist of a three-piece assembly and follow a common installation process. The three components are: a threaded compression nut/cap with internal taper; a heat-treated (surface-hardened) tapered grapple spiral teeth slip; and a bottom sub housing that contains the pressure retaining O'-ring seal arrangement.

The installation method involves sliding the connector's threaded compression nut/cap and the (surface hardened) tapered grapple spiral teeth slip over and up the Is tubing, followed by the bottom sub containing the 'O'-ring seals, which is tapped on to the end of the tubing until it passes the 'O'-ring seal area and bottoms out inside the housing. The compression nut/cap is then slid down the tube over the grapple spiral teeth slip and is joined on to the bottom sub housing thread by manually tightening down the threaded compression nut/cap with a spanner or wrench while simultaneously holding the bottom sub housing from rotating by using a second spanner or wrench. This compresses, via the taper, the grapple teeth slip on to the outside of the coil tubing to form the grip.

There are three fundamental areas that determine the success and reliability of current grapple connector design: 1: The grapple slip spiral teeth bite in to the coil tubing to provide tensile and torsion capabilities and prevent the grapple from being pulled from the tube or being rotated in the same direction as the spiral (necessary for rotating tools milling/drilling tools these all typically rotate clockwise).

2: The two 'Cr-ring elastomer seal arrangement housed inside the connector's bottom sub housing -this is essential for a pressure-tight seal to prevent pressure drop when pumping the necessary fluids through the coil tubing to operate the BHA when carrying out operations.

3: The installation procedure for the connector to ensure the tensile and torsion capabilities meet operational requirements and a pressure tight seal is achieved.

Existing Coil Tubing Grapple Connectors are prone to operational problems because of inconsistency with the installation process, which can lead to the connector slipping on the tubing and/or strangulation and collapse of the tube resulting in reduced sealing capability. Once installed, Grapple Connectors are expected to withstand upward and downward jarring (hammer action) with accelerated impacts of several 100,000 lbs force (445kN) and torsional forces of around 5,000 ft.lbs (6780 Nm) (dependent on tubing strength) during fishing /trapped in hole operations, with single straight pull loads at surface equivalent to 80% of tubing yield.

Existing external coil tubing grapple connectors generally use two clastomer seals (O'-rings) when installed to seal against the outside of the coil tubing and can be Is prone to sealing failure while under pressure causing fluid leaks and, notably, loss of operating pressure (typical internal coil tubing pressure 5,000psi (34.5 MPa)). The current problems with existing designs have been around for many years and are now inherent with grapple connector use.

For example, there arc several different brands of grapple connectors all with varying join-up threads and different tapered grapple slips rendering the installation of each connector unique to its own brand, i.e. the amount of turns required to set the grapple on the tube, the position of the '0'-ring seals and, ultimately, the effectiveness of 'O'-ring seals in this application after considering standard coil tubing is produced with surface finish and tolerances that do not have to comply with British Standard 'O'-ring sealing specifications (BS 1806:1989). In addition, the tubing suffers ovality, nicks and abrasions, and other surface damage during its production and during operations being reeled on and off the coil tubing drum rendering the tubing surface in many instances unsuitable for a pressure retaining 'Cr-ring seal.

The present invention seeks to attempt a solution to these and other problems, and is an improvement over the earlier design disclosed in W02014/033072.

Summary of the Invention

Accordingly, the invention provides a connection assembly, for connecting an item to a tube, said assembly comprising: (i) a gripper configured to pass over a tube in a first s configuration, and to grip the outside of the tube in a second configuration when a compressive force is applied thereto; (ii) a top sub-assembly having an aperture therethrough to allow it to be passed over a tube and a gripper mounted thereon; (iii) a seal housing having an aperture therethrough to allow it to be passed over the end of a tube, said aperture having an abutment face for forming a seal against a face of a sealing ring; (iv) a sealing ring, adapted to seal between said abutment face and the end face of a tube; (v) an initiator ring formed of relatively deformable material having an aperture therethrough to allow it to he passed over a tube, and interposed between the seal ring housing and the gripper; (vi) a seal housing carrier having an aperture therethrough so sized as to slidingly receive said seal housing from one end only, and to allow access to a face of said seal housing from the other end; and (vii) wherein said top sub-assembly and said seal housing carrier are adapted to be releasably held together to trap said gripper.

Such an arrangement has been found to provide a very reliable method of connecting an item to a tube, and utilises fewer working parts than earlier designs. This is particularly important for cost, and also for ease of use in e.g. an offshore environment.

Preferably said sealing ring is provided with a plurality of concentric grooves on at least one of its end faces. More preferably said sealing ring is provided with a plurality of concentric grooves on each of its end faces. Conentric grooves aid the deformation of the sealing ring, and prevent the appearance of a leakage path that might otherwise occur with a single spiral groove.

Preferably, said sealing ring is made of metal, and most preferably from the same metal as the tube to which the device is to be fitted.

In any embodiment of the assembly, it is preferred that said gripper comprises a collet. Alternative grippers may be employed, such as an elastomeric cylinder, but a collet provides a more secure fitment.

s Also in an embodiment of the invention it is preferred that said initiator ring is made of plastics, and more preferably PTFE. Such materials give appropriate deformation characteristics without causing any problems of electrolytic incompatibility.

Also in any embodiment of the invention it is preferred that said sealing ring is made from the same material as the tube to which the assembly is to be connected.

Also included within the scope of the invention is a sealing ring for use in a connection assembly described herein comprising a cylindrical ring provided with a plurality of concentric grooves on at least one of its end faces. Preferably, said sealing ring is provided with a plurality of concentric grooves on each of its end faces.

Also included within the scope of the invention is a collet for use in a connection assembly having a collet, said collet comprising a cylinder having internal grip teeth, an external buttress thread, and a plurality of through-slots said slots extending sequentially from alternate ends of the collet, and wherein said internal grip teeth are present on only one region of said collet.

Also included within the scope of the invention is a connection assembly substantially as described herein with reference to and as illustrated by any appropriate combination of Figures 1 to 11.

Also included within the scope of the invention is a collet for use in a connection assembly according to any of Claims 4 to 8 substantially as described herein with reference to and as illustrated by any appropriate combination of Figures 1-4, 10 or 11.

Also included within the scope of the invention is a method of connecting a connection assembly to a tube comprising the steps of: (1) providing a connection assembly as described herein; (ii) assembling said top sub-assembly, gripper, initiator ring, scaling ring, seal housing and seal housing carrier onto the end of a tube; (iii) applying a compressive load between said top sub-assembly and said seal housing to cause the gripper to grip the tube, and the sealing ring to seal between the end face of the tube and the seal housing; (iv) tightening the connection between the top sub-s assembly and the seal housing carrier; and (v) releasing said compressive load. An item may then be connected to said assembly.

Brief Description of the Figures

The invention will be described with reference to the accompanying drawings, in which: Figure 1 illustrates a cross-sectional view through a top sub-assembly and gripper, forming an embodiment of part of the invention; Figures 2-4 illustrate in elevation, radial cross-section and axial cross-section respectively, a gripper forming an embodiment of part of the invention; Figures 5 and 6 illustrate, in cross-section a seal housing, sealing ring and initiator ring forming an embodiment of part of the invention; Figures 7A and 7B illustrate a sealing ring in perspective and cross-sectional view respectively, and forming an embodiment of part of the invention; Figures 8A and 8B illustrate an initiator ring in perspective and cross-sectional view respectively, and forming an embodiment of part of the invention; Figure 9 illustrates, in cross-sectional view, a seal housing carrier, forming an embodiment of part of the invention; Figures 10 and 11 illustrate, in cross-sectional view, an embodiment of a device of the invention, in place on a tube; and Figure 12 illustrates, in schematic plan view, a hydraulic ram assembly for fitting a device of the invention to a tube.

Description of Preferred Embodiments

The component parts of a preferred embodiment of a connection device of the invention will first be described, followed by a description of how they may be assembled to connect to a tube.

Figure 1 illustrates in cross-sectional view a top sub-assembly 1 and a gripper 2 assembled onto a tube 3. The left-hand side of the Figure corresponds to the top (up-hole) end of the assembly, and the right-hand side to the bottom (down-hole) end. This orientation is repeated in the other Figures, for clarity. The top sub-assembly 1 is of generally cylindrical form, having an aperture therethrough to allow it to be passed over a tube 3 to which the device is to be affixed. The top sub-assembly is provided with an external thread 4 to allow it to he connected to a bottom sub-assembly to he described below.

The bottom end of the top sub-assembly is counter bored, the inside surface being provided with a coarse internal gripper thread 5 to engage the externally-threaded gripper 2. The shallow incline of the thread 5 provides the means to cause an applied compressive load to urge the gripper into gripping engagement with the outside of the tube 3.

At a top region of the top sub-assembly, a chamfered portion 6 is provided to allow a compressive load to be applied to the assembly whilst holding the assembly in axial alignment with the hydraulic press that may be used to apply the force. This is described in more detail below. A number of radially-orientated threaded grub screw holes 7 may also be provided, and provided with grub screws (not illustrated) to allow the assembly to be releasably connected to the tube 3 to aid the attachment process and to provide additional security of fixing. A number of flat portions 8 are also provided, to allow a spanner to be used to transmit rotational force to the assembly. A circumferential recess 9 is also provided to allow an identification band to be attached to the assembly.

The gripper 2, preferably in the form of a collet as described below, is provided with an external inclined thread 10 to engage with the similar thread 5 on the top sub-assembly. The inside of the generally cylindrical gripper is provided with an array of inwardly-pointing teeth 11 which, when a compressive load is applied to the gripper, bite into the outside surface of the tube 3. The gripper 2 is shorter than the counter-bored portion of the top sub-assembly 1. In particularly preferred embodiments, such as the one illustrated in Figure 1, a section of the gripper towards the bottom end is not provided with such inwardly-pointing teeth 11. By removing the teeth in this way, it ensures that the compressive loads are transmitted through the collet to the main body of the top sub-assembly, and not through to the area of the thread 4 the downhole end of the sub-assembly 1. If force were to be transmitted to this region, s there is a danger that the thread will he distorted, leading to difficulty in joining the top sub-assembly to the seal housing carrier and potential compromise of the seal. This may be readily accomplished by manufacturing a the gripper with inwardly-pointing teeth along its whole length (e.g. in the form of a spiral thread), and then counter-boring off the end of the teeth at one end of the gripper. This can be seen in the section marked 12 in Figure 1.

Figures 2-4 illustrate a gripper 2 forming part of the invention in elevation, radial cross-section and axial cross-section respectively. The gripper is in the form of a collet and is of generally cylindrical form having an aperture therethrough to allow the gripper 2 to be passed over the outside of a tube 3 on which it is to be used. The external surface of the gripper is provided with a large pitch helical thread 10 having asymmetric thread angles forming a buttress thread. The shallow angle of the teeth 13 of the thread interact with the similarly-shaped internal thread 5 in the top subassembly 1, such that a compressive load applied to the end of the gripper when in the top sub-assembly cause the teeth 11 to he urged inwardly, towards the tube 3.

The bore of the gripper 2 is provided with inwardly-facing gripping members that, in this embodiment, take the form of helically-disposed grip teeth 11. The gripper is made from a deformable strong material such as surface hardened steel. The gripper is preferably made from a resiliently deformable material, to assist in removing it from a tube when it is no longer required.

Longitudinal slots 14 are provided in the collet, extending completely through the wall 15 in the radial direction and extending from one end of the collet to a position adjacent the other end. In preferred embodiments successive slots in the collet extend from alternate ends. The inventor has found that such an arrangement prevents asymmetric deformation of the collet when compressed, and thereby improves the grip on the tube 3, and reduces internal stresses in the apparatus. In particularly preferred embodiments, eight such slots 14 are provided -four extending from one end of the collet 2 and four extending from the opposite end. The number of slots may be chosen depending on the size of the collet, larger collets having more slots to allow the stresses to be distributed around the collet's circumference.

In one end region 12 of the collet, the inwardly-pointing teeth 11 are absent, as described above.

Figure 5 illustrates, in cross-sectional view, a seal housing 16, scaling ring 17, and initiator ring 18 in exploded layout. The seal housing is of generally cylindrical form having an aperture therethrough, one end of which (the top, uphole end) is so sized as to allow it to be passed onto the end a tube 3 to which it is to be fitted. The other end (the bottom, downhole end) has a narrower bore, preferably corresponding to the bore of the tube 3 to which the device is to be attached so that no obstructions are present within the tube-device flowpath. This change in bore diameter provides the seal IS housing 16 with a step, forming a seal-engaging face 20, against which the sealing ring 17 may be abutted. An internal O'-ring groove 21 is also provided, to form a back-up seal, but more particularly to temporarily hold the seal housing on a tube to facilitate assembly. The '0'-ring itself is not illustrated, for clarity.

The seal housing is also provided with a counter-bored portion 22 at its top end, so sized as to lightly grip the external face of the initiator ring 18. An external shoulder 23 is also provided to allow the top end of the seal housing to protrude into the gap between the gripper 2 and the top sub-assembly 2, as will be illustrated below. The sealing ring 17 and initiator rings will also be described below in more detail.

The bottom end of the seal housing is also provided with an external '0'-ring groove 24 to allow an O'-ring to be fitted to temporarily hold the seal housing within the seal housing carrier (described below), and to provide a hack-up seal.

The seal housing is preferably made from hardened steel.

Figure 6 illustrates, again in cross-sectional view, a seal housing 16, scaling ring 17 and initiator ring 18 assembled for use on the end of a length of tube 3. Again, the O'-ring is omitted, for clarity.

Figures 7A and 7B illustrate, in perspective and cross-sectional views respectively a preferred sealing ring 17 forming part of the invention. The sealing ring 17 is circular, and is so sized such that the two end faces 25 of the ring are approximately the same size as the end face of a tube 3 to which the device is to he fitted. In this preferred embodiment, each end face is provided with a number of concentric circular grooves 26 extending partway into the ring. These grooves allow the sealing ring to deform more easily when under compressive load, thereby improving the seal. Concentric grooves are preferred over a single spiral groove, as a spiral groove can o provide a leakage path in the case of seal failure. By contrast, concentric grooves provide a multiple of seals -one between each groove. Typically between two and eight such grooves will he provided, e.g. four grooves, as illustrated. The sealing ring may be made of soft iron such as that sold under the Registered Trade Mark ARMCO®. Alternatively, the ring may be made of another relatively soft metal, such as aluminium or copper, or an alloy such as those sold under the Registered Trade Marks INCONEL® (alloys containing predominantly nickel and chromium) or MONEL® (alloys containing predominantly nickel and copper). In particularly preferred embodiments, however, the ring is manufactured from the same material from which the tube 3 is constructed. In this way, any unwanted electrolytic effects arc avoided.

Figures 8A and 8B illustrate, in perspective and cross-sectional views respectively a preferred initiator ring 18 forming part of the invention. The initiator ring 18 is of generally cylindrical construction, and with a diameter so sized as to fit within the counterbore 22 of the seal housing 16, and a length such that a portion of the initiator ring 18 protrudes from the end of the seal housing 16 when the ring is mounted in the housing. Typically, the initiator ring should protrude by at least 0.5mm, preferably 1mm, and generally between 0.5 and 4mm. This gives sufficient movement of the assembly when under compressive load, to enable the sealing ring 17 to be deformed sufficiently to create an effective seal. In preferred embodiments, one end of the initiator ring is provided with an external shoulder 27, leaving a protruding part 28 that can engage with the gap between the gripper 2 and the inside face of the top subassembly 1.

The initiator ring is formed of a readily deformable material (i.e. more readily deformable than the hardened steel construction of the main body of the device, and more deformable than the tube 3). In preferred embodiments, the initiator ring 18 is made of a plastics material such as PTFE.

Figure 9 illustrates, in cross-sectional view, a seal housing carrier 29 forming part of a bottom sub-assembly of a device of the invention. The carrier 29 is of generally cylindrical form and is made of metal, such as hardened steel. The carrier 29 has a stepped bore 30, larger at the top end (left hand side of Figure 9) and is sized so as to w be able to receive a seal housing 16 as described above. A carrier shoulder 31 is provided within the bore of the carrier 29 against which the bottom end face of the seal housing abuts, when assembled. The shoulder 31 is so sized as to allow a portion of the end face of the seal housing 16 to extend into the bore 30 of the carrier at its bottom end.

The top end of the carrier 29 is provided with an internal thread 32 to mate with the external thread 4 on the top sub-assembly. Threaded grub screw holes 33 arc provided around the periphery of the carrier 31 which can be provided with grub screws (not illustrated) to allow the carrier to be releasably secured to the tube 3 to which the device is to be fitted. A series of flat regions 34 arc also disposed around the outside surface of the carrier, to allow a spanner to used to provide rotational force to the carrier. A circumferential recess 35 is also provided to allow an identification band to be attached.

At the bottom end of carrier, a connection means for connecting the carrier to a tool or other device is provided. In this case, this takes the form of an external screw thread 36 and an external 'Cr-ring groove 37.

Figure 10 illustrates, in cross-sectional view, a device of the invention in position on a tube 3 to which it is to be attached, to illustrate the overall configuration of the device.

O'-rings and grub screws are omitted, for clarity. It can be seen how a portion of the end face 38 of the seal housing 16 protrudes into the bore 30 of the seal housing carrier 29.

Figure 11 illustrates, again in cross-sectional view, how the seal is formed between the device and the tube. The components of the device are illustrated in a slightly spaced-apart configuration, for clarity. After loosely assembling the device as shown in Figure 10, a compressive force is applied between the top face of the top subassembly, including the chamfered face 6 and the bottom end of the seal housing, by use of e.g. a hydraulic ram 40. The device may be mounted in a cradle (described below), with the tapered portion 6 located in a receiving recess 39 in the cradle, the interacting tapered portions serving to retain the axial alignment of the device within the cradle. A hydraulic ram 40 may then be used to exert a compressive force between the bottom end of the seal housing and top face of the top sub-assembly. As the parts of the device move relative to each other, the initiator ring exerts a compressive force on the gripper 2, causing the teeth II of the gripper to bite into the outside surface of the tube 3. As further force is applied, the initiator ring is crushed, the deformation of the ring allowing the seal housing 16 to continue to move relative to the top sub-assembly, and allowing a compressive force to be exerted on the sealing ring 17 which is itself deformed between the end face of the tube 3 and the abutment surface 20 of the seal housing, causing a fluid-tight seal to be formed.

Once a sufficient force has been exerted on the assembly to form the seal and grip, a spanner (or the like) may be used to screw the seal housing carrier 29 onto the top sub-assembly 1 whilst the force is still being applied. The compression force exerted on the top sub-assembly and consequent friction between the chamfer 6 and the recess 39 prevents rotation of the top sub-assembly. Once the assembly has been lightened in this way, the compressive force can be removed, and the device released from the cradle. The grub screws on the device may also then be secured, to provide additional security to the joint.

To dismantle the assembly, the process is merely repeated in reverse: any grub screws may be released; force is exerted on the assembly by means of the hydraulic ram; the top sub-assembly and seal housing carried are unscrewed from each other using a pair of spanners, and the compressive force is released. Once this is completed, the whole assembly may be readily dismantled.

Figure 12 illustrates in horizontal cross-sectional view a hydraulic assembly jig, generally illustrated by 41, that may be used to attach a connection device to the end of a tube 3. The jig comprises a hydraulic ram 40 actuated by delivering high pressure hydraulic fluid to a face of a piston 42. On release of the hydraulic pressure, the ram 40 returns to its at-rest position by means of a biasing spring 43. The s hydraulic ram 40 is held apart from a top-sub receiving support 39 by two arms 44.

The top-sub receiving support 39 may be configured to be removable such that different-sized top-sub receiving supports may be provided to suit a variety of sizes of connector and tubes. Similarly, the hydraulic ram 40 may he configured (e.g. by having a replaceable threaded portion) to accommodate a range of sizes of ram with to different outside diameters to suit the diameters of different sizes of tubing.

Claims

CLAIMS1. A connection assembly, for connecting an item to a tube, said assembly comprising: (i) a gripper configured to pass over a tube in a first configuration, and to grip the outside of the tube in a second configuration when a compressive force is applied thereto; (ii) a top sub-assembly having an aperture therethrough to allow it to be passed over a tube and a gripper mounted thereon; (iii) a seal housing having an aperture therethrough to allow it to be passed over the end of a tube, said aperture having an abutment face for forming a seal against a face of a sealing ring; (iv) a scaling ring, adapted to seal between said abutment face and the end face of a tube; (v) an initiator ring formed of relatively deformable material having an aperture therethrough to allow it to be passed over a tube, and interposed between the seal ring housing and the gripper; (vi) a seal housing carrier having an aperture therethrough so sized as to slidingly receive said seal housing from one end only, and to allow access to a face of said seal housing from the other end; and (vii) wherein said top sub-assembly and said seal housing carrier are adapted to be releasably held together to trap said gripper.
2. A connection assembly according to Claim I wherein said sealing ring is provided with a plurality of concentric grooves on at least one of its end faces.
3. A connection assembly according to Claim 1 wherein said sealing ring is provided with a plurality of concentric grooves on each of its end faces.

3o
4. A connection assembly according to any preceding claim wherein said sealing ring is made of metal.
5. A connection assembly according to any preceding claim, wherein said gripper comprises a collet.
6. A connection assembly according to any preceding claim wherein said initiator ring is made of plastics.s
7. A connection assembly according to Claim 6 wherein said initiator ring is made of PTFE.
8. A connection assembly according to any preceding claim wherein said scaling ring is made from the same material as the tube to which the assembly is to be connected.
9. A sealing ring for use in a connection assembly according to any preceding claim comprising a cylindrical ring provided with a plurality of concentric grooves on at least one of its end faces.Is
10. A sealing ring according to Claim 9 wherein said sealing ring is provided with a plurality of concentric grooves on each of its end faces.
11. A collet for use in a connection assembly according to any of Claims 4 to 8 comprising a cylinder having internal grip teeth, an external buttress thread, and a plurality of through-slots said slots extending sequentially from alternate ends of the collet, and wherein said internal grip teeth are present on only one region of said collet..
12. A connection assembly substantially as described herein with reference to and as illustrated by any appropriate combination of Figures 1 to 11.
13. A collet for use in a connection assembly according to any of Claims 4 to 8 suhstantially as described herein with reference to and as illustrated by any appropriate combination of Figures 1-4, 10 or 11.
14. A method of connecting a connection assembly to a tube comprising the steps of: (i) providing a connection assembly according to any preceding claim; (ii) assembling said top sub-assembly, gripper, initiator ring, sealing ring, seal housing and seal housing carrier onto the end of a tube; (iii) applying a compressive load between said top sub-assembly and said seal housing to cause the gripper to grip the tube, and the sealing ring to seal between the end face of the tube and the seal housing; (iv) tightening the connection between the top sub-assembly and the seal housing carrier; and (y) releasing said compressive load.