GB2391052A

GB2391052A - Sleeve to pile connection for offshore structures

Info

Publication number: GB2391052A
Application number: GB0214762A
Authority: GB
Inventors: Peter James Curry
Original assignee: Britannia Engineering Consultancy Ltd
Current assignee: Britannia Engineering Consultancy Ltd
Priority date: 2002-06-26
Filing date: 2002-06-26
Publication date: 2004-01-28
Anticipated expiration: 2022-06-26
Also published as: GB2391052B; GB0214762D0

Abstract

A sleeve to pile connection comprises a pile with a plurality of axially spaced circumferential grooves (26) and a sleeve (10) having at least one groove engaging member (16) resiliently biassed to engage in one of the grooves (26). A withdrawal mechanism (24) is attached to the groove engaging member (16) and is arranged to keep the groove engaging member (16) in withdrawal.

Description

1 2391052

The present invention relates to a method and arrangement 5 for locking a structure to a pile and is particularly applicable to offshore operations where a structure having sleeves or hollow legs is "pinned" to the sea bottom by piles driven through the sleeves or hollow legs.

10 The aforesaid method of stabilizing an offshore structure is well known and is described in detail in US Patent No 4,422,805 (Sweatman, assigned to Hughes Tool Co) and US Patent No 4,721,416 (Gracia, assigned to Int. Building Systems, Inc). In both these patents, the technique used to secure piles to the structure is to pump grouting into the annular gap between the inside of the sleeve or leg and the outside of the pile. This has the advantage that the piles can be driven to the maximum desirable or practical depth and then fixed to the structure where each ceases being 20 driven down. Of course, each pile in a particular structure may require to be driven to a different depth to the next pile. This is shown in US Patent No 4,372,704 (Knox, assigned to Halliburton Co), which also shows a grouting arrangement. A problem with grouting is that piping must be 2s provided to supply the grout with all the difficulties of such provision.

A further known way of coupling piles to such structures is by swaging the sleeve onto the pile. This also requires 30 providing complicated equipment at the swaging location which would be underwater and may require divers.

In my International Patent Application No PCT/GB98703631 (Publication No WO 99/29967), there is described a latching 35 arrangement in which a set of finger-like latches is disposed around the inside of a sleeve so that the latches can spring into engagement with a groove around the pile to

lock the pile and sleeve together. Such an arrangement works well. However, an alternative arrangement would work equally well and this alternative can be used either to provide additional latching for the arrangement shown in my s PCT application or else as a standalone latching arrangement to resist upward forces or both upward and downward forces on the sleeve are likely to be less. It may be mentioned here that high upward forces have been experienced when fishing vessels attempt to winch fishing tackle off an lo offshore structure after snagging the tackle on the structure. Thus a sleeve to pile connection according to the invention comprises a plurality of circumferentially disposed grooves on the pile, adjacent grooves separated axially and at least one groove engaging member mounted to said sleeve resiliently biased to engage in a said groove and removal means to reverse such engagement.

20 The term "sleeve" is used to include both a short sleeve of the sort shown in US Patent No 4,721,416 and a hollow leg as shown in US Patent No 4,372,704.

The advantage of such an arrangement is that the groove 25 engaging member can be held in a withdrawn position whilst the sleeved structure is towed to its offshore site and then released by removing the removable means after insertion and driving of the pile into the sleeve.

30 In a situation where it is desired to detach the sleeved structure from the piles, which was not possible with the known grouted connection unless the piles were cut away, it is simple to provide the groove engaging member with a withdrawal means arranged so that the member can be pulled 3s out of the pile groove and by twisting the member in a housing or cowling, it can be held in a disengaged position.

This is a simple operation for a remotely operated

underwater vehicle (ROY) to perform.

The groove engaging member is preferably provided with a notched nose with a face slightly angled from the horizontal 5 and which corresponds in shape with a groove of the pile which has a somewhat dovetailed shape. This ensures good engagement. The face on the nose may face either upwards or downwards or in both directions depending on the direction of loading to be resisted.

The invention will now be described by way of example with reference to the accompanying drawings, in which: Figure 1 shows in perspective a sleeve of an offshore 5 structure having four groove-engaging members of a sleeve-to-pile connection according to the invention; Figure 2 shows in a cut-away perspective view the sleeve-to-pile connection of Figure 1 in which only the 20 single groove-engaging member is shown; Figures 3 and 4 are cut-away side views of the groove-

engaging member shown in Figure 2 showing the engaging member in a position prior to release and a position after pin release, respectively; Figure 5 is a section taken on A-A of Figure 3; Figure 6 is a section taken on B-B of Figure 3; Figure 7 is an exploded view in perspective of the groove-engaging member, its associated parts and housing or cowling of Figure 2; and Figure 7A is a plan view of the lug of Figure 7.

In the drawings, Figure 1 shows a sleeve 10 which is attached by members 11 to other parts of an offshore

structure such as a submersible offshore structure. Welded to sleeve 10 by means of brackets 12 are four hollow housing members or cowlings 14 in which are mounted groove-engaging members 16, the noses 18 of which are shown projecting 5 through wall 20 of sleeve 10. Each groove-engaging member is held in a retracted position by a removal means being a pin 22, as will be shown in detail in the remaining drawings. 10 A withdrawal means, being a grab handle 24, is attached to the rear end of the engaging member or lug 16. The grab handle 24 is suitably shaped for an ROV to grab it for withdrawal from groove 26 of pile 28. Lug 16 is urged into engagement with groove 26 by means of a coiled spring 30 which acts against plate 32 fixed inside cowling 14. Each of the pins 22 as shown in Figures 5 and 6 and the exploded view in Figure 7 is inserted through the hole 34 in cowling 14 and then through back plate 36 to which grab handle 24 is secured. The grooves 26 may be formed inwardly in the pile 20 as shown at 26 in Figure 2 or formed as at 26' by the application of upward and downward facing annular ramps or collars 27 and 27' Cowling 14 is provided with two pairs of cut-away portions 25 40 and 42 which are at the outer end of cowling 14. These recesses receive grab handle 24 so that recess pair 40 holds the grab handle when the lug is in the retracted position, as shown in Figure 3, and recess pair 42 receives the grab handle when the lug is in the groove-engaging position, as so shown in Figure 4. In Figure 3 there may be seen seals 62 and 63 which retain grease inserted through grease nipples 64. This acts to prevent corrosion of spring 30.

The nose 18 of the lug has a face 44 angled at a slight 35 angle 9 of about 15 to the horizontal which corresponds with a similarly angled face 46 of groove 26 of pile 28 (see Figure 4). As shown in broken lines in Figure 4, nose 18

may also or alternatively have a downward facing angled face 45 angled at about 15 depending on the direction of loading to be resisted. Where it is anticipated the lug has to be withdrawn, the pile grooves shown at 26" and the nose have engagement surfaces 46 and 44 which are perpendicular to the outer surface of the pile. Nose 18 is curved in the horizontal plane to conform with the curve of the pile grooves (see Figure 7A). The lug also has a chamfered face 48 to prevent lug 16 from being damaged on pile insertion.

10 Guides 17 are welded to the inside of wall 20 either side of the holes 19 where noses 18 project through the wall so as to guide the pile away from the lugs on pile insertion.

In operation, the offshore structure having sleeve 10 is 5 prepared in its fabrication yard for removal to the offshore site location and this includes pinning the lugs shown in Figure 1 in the position shown in Figure 3. Lug 16 is then retained against spring 30. After installing the structure so that the several sleeves 10 on the structure are now in a 20 position to receive the piles 28, the piles are inserted with the lugs 16 still pinned back. As the piles are driven down to the necessary level, adjacent grooves 26 can be seen by an ROV camera passing down through the sleeve. The grooves 26 in the piles are spaced apart at a distance so 2s that the groove next above groove 26 on the pile can be seen level with the top edge 50 of sleeve 10. This enables pile driving to be stopped at the level where a pile groove is level with edge 50 so that noses 18 of lugs 16 will then be precisely at the level of groove 26. Pins 22 can then be 30 removed so that lugs 16 are sprung into engagement with groove 26 and sleeve 10 is then locked to pile 28.

Alternatively an opening 60 or 60' may be introduced into sleeve 10 to visually confirm the groove is approaching the 35 lug elevation. At this stage the pin 22 may be released and the lug 16 deployed against the pile groove. The movement of lug 16 into groove 26 will be confirmed by the position

and movement of the handle 24 in recess pair 42. Should the groove not quite align correctly the pile could be driven a small distance further until alignment occurs and the lug 16 moves into the groove as witnessed from the position and 5 movement of the handle 24.

If the lugs are to be withdrawn to disconnect sleeves 10 from piles 28, then an ROV is used to grab handle 24 and pull it out and then twist it into engagement with recess 10 pair 40.

Claims

- CLAIMS

1. A sleeve-to-pile connection comprising a plurality of circumferentially-disposed grooves on the pile, adjacent 5 grooves separated axially and at least one groove-engaging member mounted to said sleeve resiliently biased to engage in a said groove and removal means to prevent such engagement. lo

2. The connection of claim 1 in which the groove-engaging member is provided with a withdrawal means arranged so that the member can be pulled out of the pile groove and by twisting the member in a housing or cowling, it can be held in a disengaged position.

3. The connection of claim 1 or 2 in which the groove-

engaging member is provided with a notched nose having a face slightly angled from the horizontal and which corresponds in shape with a said groove of the pile.

4. The connection of claim 3 in which the notched nose has two faces one facing upwards and the other downwards, both faces being slightly angled from the horizontal.

25

5. The connection of claim 2 in which the withdrawal means is provided with a tee-shaped handle, the arms to fit in recesses on the outer end of a housing arranged to receive the groove-engaging member.

30

6. The connection of any one of the preceding claims wherein the interior of the sleeve has one or more guides arranged to deflect the pile away from the or each groove-

engaging member.

35

7. The connection of any one of the preceding claims wherein the grooves on the pile are formed as being indented into the pile.

A ^

8. The connection of any one of claims 1 to 6 wherein the grooves on the pile are formed as between upwardly and downwardly facing annular ramped portions.

9. A sleeve and pile connection for locking structure to a pile, substantially as described with reference to the lo accompanying drawings.

9. A sleeve-to-pile connection for locking structure to a pile, substantially as described with reference to the accompanying drawings.

lo

10. A method of connecting a pile to a structure, substantially as hereinbefore described.

Amendments to the claims have been filed as follows 1. A sleeve and pile connection including the sleeve and pile, the connection comprising a plurality of 5 circumferentially-disposed grooves on the pile, adjacent grooves separated axially and at least one groove-engaging member mounted to said sleeve resiliently biased to engage in a said groove and removal means to prevent such engagement and wherein the sleeve is arranged to fit around lo the pile.

3. The connection of claim 1 or 2 in which the groove-

engaging member is provided with a notched nose having a 20 face slightly angled from the horizontal and which corresponds in shape with a said groove of the pile.

4. The connection of claim 3 in which the notched nose has two faces one facing upwards and the other downwards, both 25 faces being slightly angled from the horizontal.

5. The connection of claim 2 in which the withdrawal means is provided with a tee-shaped handle, the arms to fit in recesses on the outer end of a housing arranged to receive 30 the groove-engaging member.

6. The connection of any one of the preceding claims wherein the interior of the sleeve has one or more guides arranged to deflect the pile away from the or each groove 35 engaging member.

7. The connection of any one of the preceding claims

1) wherein the grooves on the pile are formed as being indented into the pile.

8. The connection of any one of claims 1 to 6 wherein the 5 grooves on the pile are formed as between upwardly and downwardly facing annular ramped portions.