LOCKING APPARATUS FOR DRILLING RIG COMPONENTS

Abstract

The present application relates to a locking apparatus for locking axial ends of first and second drilling rig components in a connected state, the connected state established by sufficiently rotating the first drilling rig component relative to the second drilling rig component in a first direction. The apparatus includes a first locking means that enables the first and second drilling rig components to be locked in their connected state by causing, during rotation of the first drilling rig component in the first direction, the locking apparatus to engage with the first drilling rig component in a configuration that prevents the first drilling rig component from rotating in a direction opposite to the first direction. The apparatus further includes a second locking means that enables the locking apparatus to be prevented from rotation relative to the second drilling rig component, including during rotation of the first drilling rig component in the first direction, the locking apparatus thereby preventing relative rotation between the first and second drilling rig components.

Claims

1. A locking apparatus for locking axial ends of first and second drilling rig components in a connected state, the connected state established by sufficiently rotating the first drilling rig component relative to the second drilling rig component in a first direction, the apparatus including: a first locking means that enables the first and second drilling rig components to be locked in their connected state by causing, during rotation of the first drilling rig component in the first direction, the locking apparatus to engage with the first drilling rig component in a configuration that prevents the first drilling rig component from rotating in a direction opposite to the first direction, and a second locking means that enables the locking apparatus to be prevented from rotation relative to the second drilling rig component, including during rotation of the first drilling rig component in the first direction, the locking apparatus thereby preventing relative rotation between the first and second drilling rig components.

2. A locking apparatus according to claim 1, wherein the locking apparatus includes a single locking ring, and the first locking means is a ratchet type locking mechanism comprising a set of ratchet teeth associated with the locking ring and configured to engage with a complementary set of ratchet teeth associated with the first drilling rig component.

3. A locking apparatus according to claim 2, wherein the second locking means is a spline type locking mechanism comprising a set of radially projecting splines associated with the locking ring and configured to engage with a complementary set of radially projecting splines associated with the second drilling rig component, the splines allowing axial motion of the locking ring relative to the second drilling rig component but preventing rotational motion of the locking ring.

4. A locking apparatus according to claim 3, wherein the locking ring includes internally projecting splines and the second drilling rig component includes corresponding externally projecting splines.

5. A locking apparatus according to claim 4, wherein the locking ring is secured to the second drilling rig component prior to connecting the first drilling rig component to the second drilling rig component, by axially aligning the internal splines of the locking ring with the external splines of the second drilling rig component and then sliding the locking ring in an axial direction towards the second drilling rig component so that the respective splines engage.

6. A locking apparatus according to claim 5, wherein: the locking ring encounters a circlip journaled around the second drilling rig component a predetermined distance inward from the engaging end of the second drilling rig component, the circlip preventing sliding motion of the locking ring beyond the circlip, the circlip thereby providing a means of abutment for the locking ring, and a rubber wedge or O-ring is disposed between the locking ring and circlip to absorb vibration and prevent wear and tear that would otherwise result from direct contact between the locking ring and circlip.

7. A locking apparatus according to claim 1, wherein the locking apparatus includes a first locking ring associated with the first drilling rig component and a second locking ring associated with the second drilling ring component, and the first locking means is a ratchet type locking mechanism comprising a set of ratchet teeth associated with the first locking ring and configured to engage with a complementary set of ratchet teeth associated with the second locking ring.

8. A locking apparatus according to claim 7, wherein the second locking means is a spline type locking mechanism comprising a set of radially projecting splines associated with the second locking ring and configured to engage with a complementary set of radially projecting splines associated with the second drilling rig component, the splines allowing axial motion of the second locking ring relative to the second drilling rig component but preventing rotational motion of the second locking ring.

9. A locking apparatus according to claim 8, wherein the first locking ring also includes a set of radially projecting splines configured to engage with a complementary set of radially projecting splines associated with the first drilling rig component, the splines allowing axial motion of the first locking ring relative to the first drilling rig component but preventing rotational motion of the first locking ring.

10. A locking apparatus according to claim 9, wherein the first and second locking ring include internal splines and the respective first and second drilling rig components include corresponding external splines.

11. A locking apparatus according to claim 10, wherein the first locking ring is secured to the first drilling rig component and the second locking ring is secured to the second drilling rig component prior to connecting the first drilling rig component to the second drilling rig component, by axially aligning the internal splines of each locking ring with the external splines of the corresponding drilling rig component, and then sliding the locking rings in an axial direction so that the respective splines engage.

12. A locking apparatus according to claim 11, wherein: the first locking ring encounters a circlip journaled around the first drilling rig component a predetermined distance inward from the engaging end of the first drilling rig component, the circlip preventing sliding motion of the first locking ring beyond the circlip, the circlip thereby providing a means of abutment for the first locking ring, and a rubber wedge or O-ring is disposed between the first locking ring and circlip to absorb vibration and prevent wear and tear that would otherwise result from direct contact between the first locking ring and circlip.

13. A locking apparatus according to claim 7, wherein: the second locking ring encounters a shoulder associated with the second drilling rig component a predetermined distance inward from the engaging end of the second drilling rig component, the shoulder preventing sliding motion of the second locking ring beyond the shoulder, the shoulder thereby providing a means of abutment for the second locking ring, and a rubber wedge or O-ring is disposed between the second locking ring and shoulder to absorb vibration and prevent wear and tear that would otherwise result from direct contact between the second locking ring and shoulder.

14. A locking apparatus according to claim 2, wherein each drilling rig component and locking ring is substantially cylindrically shaped and thereby has a substantially circular edge surface at each engaging end thereof such that when a set of ratchet teeth is associated with the engaging end, the ratchet teeth are arranged around the edge surface in a substantially circular arrangement with teeth projecting outwardly from the surface in a substantially axial direction.

15. A locking apparatus according to claim 14, wherein: the teeth protrude axially at an angle of between 30 and 50 degrees from the edge surface, or the teeth protrude axially at an angle of 40 degrees from the edge surface.

16. A locking apparatus according to claim 1, wherein the first and second drilling rig components are connected by rotatably engaging a frusto-conical projection extending from the axial end of one drilling rig component with a corresponding frusto-conical bore in the axial end of the other drilling rig component, wherein the connected state is achieved once an abutment surface at a base of the projection comes into contact with a corresponding abutment surface at the axial end of the drilling rig component that includes the frusto-conical bore.

17. A locking apparatus according to claim 1, further including an annular protector for use when the first and second drilling rig components are locked in their connected state, the annular protector fitted over any exposed locking means to prevent ingress of particles during a drilling operation.

18. A locking apparatus according to claim 1, wherein: the first drilling rig component is a rotary head and the second drilling rig component is a cross-over sub, or the first drilling rig component is a rotary head and the second drilling rig component is a cushion sub, or the first drilling rig component is a rotary head and the second drilling rig component is a first drill rod, or the first drilling rig component is a cross-over sub and the second drilling rig component is a first drill rod, or the first drilling rig component is a cross-over sub and the second drilling rig component is a drill bit, or the first drilling rig component is cushion sub and the second drilling rig component is a first drill rod, or the first drilling rig component is a cushion sub and the second drilling rig component is a cross-over sub, or the first drilling rig component is a first drill rod and the second drilling rig component is a second drill rod, or the first drilling rig component is a first drill rod and the second drilling rig component is a cross-over sub, or the first drilling rig component is a drill rod and the second drilling rig component is a drill bit.

19. A drilling rig including: a first drilling component, a second drilling component, and a locking apparatus for the first and second drilling components, the locking apparatus configured in accordance with claim 1.

20. A method of assembling a drilling rig configured in accordance with claim 19, the method including: mounting the locking apparatus to the second drilling rig component such that the locking apparatus, or a locking ring associated therewith, is prevented from rotation relative to the second drilling rig component; connecting the first drilling rig component to the second drilling component by rotating at least the first drilling rig component in said first direction and thereby causing the two components to rotatably engage, wherein during rotation of the first drilling rig component in the first direction, the first locking means associated with the locking apparatus is caused to engage with the first drilling rig component in a manner that allows further rotation of the first drilling rig component in the first direction but prevents the first drilling rig component from rotation in a direction opposite to the first direction; and continuing to rotate the first drilling rig component until the first and second drilling rig components are in their connected state.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0067] Features of the present disclosure are illustrated by way of example and not limited in the following figure(s), in which like numerals indicate like elements, in which:

[0068] FIG. 1 illustrates a first exploded, perspective view of a portion of a drilling rig comprising two drilling rig components and a locking apparatus according to an embodiment of the present invention.

[0069] FIG. 2 illustrates a second exploded, perspective view of the drilling rig portion illustrated in FIG. 1.

[0070] FIG. 3 illustrates a perspective view of the two components shown in FIG. 1 in an assembled state and prevented from disengagement by the locking apparatus.

[0071] FIG. 4 illustrates the perspective, assembled view of FIG. 3 including a tooth protector associated with the locking apparatus.

[0072] FIG. 5 a cross-sectional view of the assembled components shown in FIG. 4.

[0073] FIG. 6 illustrates two drilling rig components connected and prevented from disengaging using a first and second locking ring associated with a locking apparatus configured in accordance with an alternative embodiment.

DETAILED DESCRIPTION OF THE EMBODIMENT(S) OF THE INVENTION

[0074] For simplicity and illustrative purposes, the present disclosure is described by referring to an embodiment thereof. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present disclosure. It will be readily apparent however, that the present disclosure may be practiced without limitation to these specific details. In other instances, some methods and structures have not been described in detail to avoid unnecessarily obscuring the present disclosure.

[0075] As used herein, the terms “a” and “an” are intended to denote at least one of a particular element, the term “includes” means includes but not limited to, the term “including” means including but not limited to, and the term “based on” means based at least in part on.

[0076] The present invention relates to a locking apparatus (10) for preventing rotation (disengagement) between the axial ends (12) and (14) of respective first and second drilling rig components (16) and (18) connected coaxially along a longitudinal axis (19). The drilling rig components (16) and (18) are rotatably connected, i.e. by rotation of the first drilling rig component 16 relative to the second drilling rig component (18) in a first rotational direction (20) until the first and second drilling rig components are in a connected state, as described in greater detail below.

[0077] The locking apparatus (10) is used to ensure that the established connection between alternatively configured drilling rig components is maintained. The two drilling rig components that are connected may include, but are not limited to, a rotatory head, a cross-over sub, a cushion sub, a drill rod, and a drill bit.

[0078] The present invention further relates to a drilling rig including the first and second drilling rig components (16) and (18), and the locking apparatus (10) for locking the first and second drilling components in their connected state.

[0079] FIGS. 1 to 5 illustrate the use of a locking apparatus in the form of a locking ring (10) for locking (i.e. preventing disengagement between) a cushion sub component (16) and a cross-over sub component (18). As mentioned above, these represent two examples of drilling rig components, but the locking ring (10) can be used to lock other components of a drilling rig.

[0080] It will be appreciated that the locking ring (10) is in the form of an annular ring configured to be associated with the cross-over sub component (18) in a manner that prevents rotation of the locking ring (10) relative to the component (18). The manner in which this is achieved will be described in greater detail below. The locking apparatus (ring) further includes teeth (22a) which form part of a first locking means. The first locking means further includes teeth (22b) associated with the first drilling rig component (16) and enables the two components (16) and (18) to be locked in their connected state by causing, during rotation of the component (16) in the first direction (20), the teeth (22a) of the locking ring (10) to engage with the teeth (22b) of the first drilling rig component (16). It will become apparent that this engagement utilising the first locking means is such that the component (16) is prevented from rotation in a rotational direction opposite to the first direction (20). The locking ring (10) thereby prevents, by action of the first locking means, relative rotation between the first (16) and second (18) components once the components have been rotationally engaged and in their connected state.

[0081] As shown in FIG. 1, the locking ring (10) includes a first axial end (24) which includes the teeth (22a) associated with the first locking means, and a second axial end (26) which includes internal vertical splines (28a) forming part of a second locking means which also includes external vertical splines (28b) of the second drilling rig component (18). The respective splines are configured to engage and prevent rotation of the locking ring (10) relative to the second drilling rig component (18).

[0082] It is to be understood that reference to “vertical”, when describing the splines (28a) and (28b), or other splines described herein in a similar manner, is representative of the direction of splines when the drilling rig components are assembled in a vertical arrangement (e.g. during a drilling operation). These splines may also be characterised as projecting radially (i.e. from an internal or external surface of a drilling rig component and/or locking ring) and extending axially (i.e. in the same direction as longitudinal axis (19)).

[0083] Accordingly, it will be appreciated that in addition to the teeth (22a) associated with the locking ring (10), the first locking means includes a set of teeth (22b) associated with the first drilling rig component (16). Accordingly, the first locking means is a ratchet type locking mechanism whereby the locking ring (10) includes a set of ratchet teeth (22a) and the first drilling rig component (16) includes a complimentary set of ratchet teeth (22b). In this way, when the locking ring (10) engages the second drilling rig component (18), and the first drilling rig component has been drawn sufficiently towards the locking ring (10) during rotation of the component (16) in the first rotational direction (20), the two sets of teeth (22a) and (22b) will eventually come into contact and start to rotatably interact. Such interaction continues in order to allow rotation of the first drilling rig component (16) in the first direction (20), until the two components become fully connected and the first drilling rig component (16) is prevented from further rotational motion in the first direction (20). The locking ring (10) prevents rotation of the first drilling rig component (16) in the opposite direction, thereby preventing the two components (16) and (18) from disengaging once in their connected state.

[0084] As described above, at a drill site (not shown), the drilling rig components (16) and (18) will generally be assembled such that they extend substantially vertically. Accordingly, the rachet type mechanism (i.e. teeth (22a) associated with the locking ring (10) and teeth (22b) associated with the first drilling rig component (16)) will extend substantially horizontally such that the first axial end (24) of the locking ring (10) includes a horizontal set of ratchet teeth (22a), and the engaging axial end (12) of the first drilling rig component (16) also includes a horizontal set of ratchet teeth (22b). In the embodiment shown, the components (16) and (18) are substantially cylindrical, and the respective teeth (22a) and (22b) protrude axially from each engaging end of the component (16) and the locking ring (10) in a substantially annular arrangement. In an embodiment, there are an even number of teeth disposed around each engaging end of the first drilling rig component (16) and locking ring (10), and the skilled addressee will appreciate that the number of teeth required will increase as the size of the first drilling rig component (16) and locking ring (10) increases.

[0085] The angle of protrusion of the teeth (22) from each of the engaging ends of the component (16) and locking ring (10) is such that the teeth (22) enable rotation in one direction (e.g. direction (20)), but prevent rotation in the opposite rotational direction, as described above. According to an embodiment, the teeth (22a) and (22b) protrude axially at an angle of between 30 and 50 degrees, e.g. 40 degrees.

[0086] In the embodiment shown in FIGS. 1 to 5, the second locking means, which enables the locking ring (10) to slide axially relative to the end (14) of the second drilling rig component (18) whilst preventing rotation of the locking ring (10), includes internal vertical splines (28a) associated with the second axial end (26) of the locking ring (10) and corresponding external vertical splines (28b) associated with the axial end (14) of the second drilling component (18). It will be appreciated that the locking ring (10) is secured to the second drilling rig component (18) prior to connecting the first drilling rig component (16) to the second drilling rig component (18) by way of rotational engagement, and this is achieved by axially aligning the internal vertical splines (28a) of the locking ring (10) with the external vertical splines (28b) of the second drilling rig component (18) before sliding the locking ring (10) in an axial direction towards the second drilling rig component (18) so that the respective splines engage.

[0087] When assembling a drilling rig including components (16) and (18) and locking ring (10), the second drilling rig component (18) requires a means of preventing axial movement of the locking ring (10) beyond a certain point as the locking ring (10) is fitted onto the second drilling rig component (18), to ensure the locking ring (10) remains in the desired position for locking the first drilling rig component (16). In this regard, and as shown in FIGS. 1 to 5, the second axial end (26) of the locking ring (10) encounters a circlip (30) journaled around the second drilling rig component (18) a predetermined distance from the axial end (14) of the second drilling rig component (18), the circlip (30) preventing sliding (axial) motion of the locking ring (10) beyond the circlip (30). In this way, the circlip (30) provides a means of abutment for the second axial end (26) of the locking ring (10). As also shown in the drawings, a rubber wedge or O-ring (32) may be positioned between the locking ring (10) and circlip (30) to absorb vibration and prevent wear and tear that would otherwise result from direct contact between the locking ring (10) and the circlip (30).

[0088] Accordingly, the steps of assembling the drilling rig components (16) and (18) together with the locking ring (10) should now be appreciated. In this regard, the steps include: [0089] fitting the circlip (30) and O-ring (32) onto the second drilling rig component (18) at the relevant position inward from the axial end (14) of the second drilling rig component (18)—this position could be marked or indented to enable an operator to see where the circlip (30) and O-ring (32) need to be positioned; [0090] fitting the locking ring (10) onto the second drilling rig component (18) by causing the vertical (axial) splines (28a) associated with the locking ring (10) and vertical (axial) splines (28b) associated with the second drilling rig component (18) to engage, wherein the locking ring (10) slides axially along the second drilling rig component (18) until the locking ring (10) abuts with the rubber O-ring (32); [0091] the first drilling rig component (16) is then drawn closer towards the second drilling rig component (18) to enable the components to connect. In the embodiment shown, this connection is achieved by causing the frusto-conical projection (33) extending from the axial end (14) of the second drilling rig component (18) to be inserted into a corresponding frusto-conical bore (34) in the axial end (12) of the first drilling rig component (16); [0092] rotating the first drilling rig component (16) in the first direction (20) causing the first and second drilling rig components to rotatably engage, i.e. by engagement between the frusto-conical projection (33) and the frusto-conical bore (34). The rotation of the first drilling rig component (16) in the first direction draws the components closer and eventually causes the teeth (22a) associated with the locking ring (10) and the teeth (22b) associated with the first drilling rig component (16) to rotatably interact, i.e. the respective set of teeth are configured to allow further rotation of the first drilling rig component (16) in the first direction (20) but preventing rotation in the opposite direction; [0093] further rotation (tightening) of the first drilling rig component (16) in the first direction (20) against the second drilling rig component (18), the axial end 14 of the second drilling rig component (18) including an abutment surface (35) with which a corresponding abutment surface (36) associated with the axial end (12) of the first drilling rig component (16) comes into contact once the first drilling rig component (16) has been sufficiently tightened, the abutment surfaces (35/36) thereby preventing further rotation of the first drilling rig component (16) in the first direction (20) (as shown most clearly in the cross sectional view of FIG. 5).

[0094] The connected state between the first (16) and second (18) component is shown in FIG. 3, and it is at this point that the ratchet teeth (22a) and (22b) engage and prevent rotation of the first drilling rig component (16) in a direction opposite to the first direction (20). The location of the circlip (30) is such that its distance inward from the axial end (14) of the second drilling rig component (18) substantially corresponds with the length of the locking ring (10) such that when the locking ring (10) is mounted onto the second drilling rig component (18) (through engagement between vertical splines (28a) and (28b)), the horizontal teeth (22a) associated with the locking ring end (24) are substantially aligned radially with the abutment surface (35) of the second drilling rig component axial end (14). In this way, as the first drilling rig component (16) and the second drilling rig component (18) are drawn closer together towards their connected state, the teeth (22a) and (22b) associated with the ratchet type locking mechanism eventually commence their engagement to prevent rotation of the first drilling rig component (16) in the opposite direction, thereby locking the two components (16) and (18) in their connected state.

[0095] FIG. 4 illustrates the use of a tooth protector (37) which is fitted over the exposed engaging ratchet teeth (22) when the first and second drilling rig components are in a connected and locked state, to prevent ingress of dust and other material during a drilling operation.

[0096] In summary, the method by which a drilling rig comprising a first and second drilling rig component (16) and (18) may be assembled, includes mounting the locking apparatus (10) to the second drilling rig component (18) such that the locking apparatus (10) is prevented from rotation relative to the second drilling rig component (18), and connecting the first drilling component (16) to the second drilling component (18) by rotating at least the first drilling rig component (16) in a first direction (20), thereby causing the two components to rotatably engage. During rotation of the first drilling rig component (16) in the first direction (20), the ratchet type locking teeth (22a) associated with the locking apparatus (10) are caused to engage corresponding teeth (22b) associated with the first drilling rig component (16) in a manner that allows further rotation of the first drilling rig component (16) in the first direction (20) but prevents the first drilling rig component (16) from rotation in a direction opposite to the first direction (20) due to abutment between surfaces (35) and (36). The first drilling rig component (16) may then continue to be rotated and tightened against the second drilling rig component (18) until it can no longer rotate in the first direction (20). In this state, the first and second drilling rig components are effectively locked together since the first drilling rig component (16) is no longer capable of rotation in either direction. As an additional step, as described earlier, a tooth protector (37) may then be fitted over the exposed ratchet teeth (22).

[0097] The skilled addressee will appreciate that by being allowed to assemble two components of a drilling rig in this manner, an operator no longer experiences difficulties associated with having to rotate an entire component in an effort to align radially projecting splines to lock the components. Whilst the locking ring (10) along with the second drilling rig component (18) of the present invention do include vertical splines (28a) and (28b) respectively, and the splines first need to be aligned before sliding the locking ring (10) onto the second drilling rig component (18), this is not difficult to achieve in the field because this step occurs prior to the first and second drilling rig component being connected, hence the locking ring (10) is not already fixed to another component and can be manually handled at that point in the assembly process. In other words, there is no difficulty in manually aligning the splines and sliding the locking ring (10) onto the second drilling rig component (18).

[0098] In order to unlock the two drilling rig components and enable the rotation of the first drilling rig component (16) in the opposite direction, the tooth protector (37) may be removed and the circlip (30) may be disengaged. The disengagement of the circlip (30) allows the locking ring (10) to be moved axially away from the first drilling rig component (16), i.e. in the direction of the second drilling rig component (18). The ratchet teeth (22a) associated with the locking ring (10) and the first drilling rig component (16) may be disengaged from teeth (22b), enabling the first drilling rig component (16) to be rotated in the opposite direction.

[0099] Whilst the embodiment shown in FIGS. 1 to 4 illustrate a first drilling rig component in the form of a cushion sub (16) and a second drilling rig component in the form of a cross-over sub (18), as mentioned previously, the locking apparatus (10) could be used to connect other types of components associated with a drilling rig such as a rotary head, a drill rod, a drill bit, etc.

[0100] FIG. 6 illustrates a locking apparatus (100) including a first locking ring (102) and a second locking ring (104) used to lock two drilling rig components (106) and (108) in accordance with an alternative embodiment. It should be understood that whilst an alternative embodiment is shown in FIG. 6, where certain features associated with the two components are identical or perform a similar function as features previously described with respect to the embodiment shown in FIGS. 1 to 5, the same numerals are used to reference those identical or similar features.

[0101] In the alternative embodiment of FIG. 6, the first drilling rig component (106) is a cross-over sub, and the second drilling rig component (108) is a cushion sub. In this alternative embodiment, the reader will appreciate that rather than having ratchet teeth projecting axially from the engaging end of the first drilling rig component (106), ratchet teeth (110a) form part of the first locking ring (102) associated with the first drilling rig component (106), such that the first locking ring (102) includes ratchet teeth (110a) projecting axially from the axial end thereof and thereby adapted to engage with ratchet teeth (110b) of the second locking ring (104) which is associated with the second drilling rig component (108).

[0102] The first locking ring (102) further includes internal vertical splines (112a) adapted to engage with corresponding external vertical splines (112b) associated with the axial engaging end of the first drilling rig component (106). The first locking ring (102) also abuts against a rubber O-ring (113) and associated circlip (not shown) journaled around the first drilling rig component (106) to prevent further sliding (axial) motion of the first locking ring (102) beyond the O-ring (113) and associated circlip when the first locking ring (102) is being fitted to the first drilling rig component (106) and during use.

[0103] The second locking ring (104) is similarly associated with the second drilling rig component (108) in that each includes correspondingly shaped, vertical splines (114a) and (114b) respectively, which are configured for engagement in a manner that allows for axial motion but not rotation motion. The second locking ring (104) includes the ratchet teeth (110b) for engaging with ratchet teeth (110a) to lock the two components together, as previously described. The second locking ring (104) is prevented from axial movement beyond the splines (towards the second drilling rig component (108)) by a shoulder (120) associated with the second drilling rig component (108) and associated O-ring (122). Similar to the tooth protector (37) in locking ring (10), the locking apparatus (100) uses a similar tooth protector (124) to protect the engaging teeth (110a) and (110b) of locking rings (102) and (104).

[0104] It will be appreciated that whilst the locking ring (100) shown in FIG. 6 is configured in an alternative manner as compared with the locking ring (10) shown in FIGS. 1 to 5 in that it comprises two locking rings (102) and (104) as compared with a single locking ring, it generally performs similar functions and addresses the same problems. In particular, the two locking rings (102) and (104) associated with components (106) and (108) respectively are able to engage (via their ratchet teeth (110a) and (110b)) and thereby lock the connection between the two components without requiring splines to be axially aligned during the locking process. The ratchet type engagement between the two locking rings facilitates the process of locking the two components in the field in that the locking is achieved during rotation of one component relative to the other (i.e. at the same time as connecting the two components). In this way, the locking occurs in a manner that does not compromise (i.e. loosen) the connection between the two components.

[0105] The steps associated with assembling the drilling rig components shown in FIG. 6 will not be described again in detail in the interest of brevity.

[0106] The skilled addressee will appreciate that in the embodiment of FIG. 6, when the drilling rig is arranged vertically and the first drilling rig component (106) is positioned above the second drilling rig component (108), the first locking ring (102) will have a tendency to slide downwards towards the second locking ring (104) during the process of connecting the two components. In order to avoid the sliding down of the first locking ring (102) a grub screw or similar retaining device (not shown) may be utilised to maintain the first locking ring (102) engaged with the first drilling rig component (106) when required.

[0107] In order to disengage the first and second drilling rig components shown in FIG. 6, the teeth (110a) and (110b) need to be disengaged and this can be achieved by, for example, disengaging the circlip associated with rubber O-ring (113).

[0108] Throughout this specification and claims which follow, unless the context requires otherwise, the word “comprise”, and variations such as “comprises” and “comprising”, will be understood to mean the inclusion of a stated feature or step, or group of features or steps, but not the exclusion of any other feature or step, or group of features or steps.

[0109] The reference to any prior art in this specification is not, and should not be taken as, an acknowledgement or any suggestion that the prior art forms part of the common general knowledge.