In offshore applications, there are several ways of connecting piles to pile sleeves, such as providing an annular space between the pile and pile sleeve and then when assembly is required, grouting the annular space. In another arrangement, the pile is swaged into prepared grooves provided in the pile sleeve, and in yet a further arrangement, a large and heavy pin is inserted through the pile and pile sleeve. When used underwater, the connection is difficult and may well involve the use of divers.

Accordingly, a tubular connection according to the invention comprises a first tube and a second tube, one having a part insertable into the other in an axial direction, the first tube having a first circumferential recess and a second circumferential recess, the second tube having a first set of resiliently biased latching means latchingly engageable in the first recess and a second set of resiliently biased latching means latchingly engageable in the second recess and corresponding abutments on the first recess and first set so that when mutually engaged axial movement is prevented in a first said axial direction and when the second recess and second set are mutually engaged axial movement is prevented in a second said axial direction opposite the first direction.

Engagement between the tubes preventing relative axial movement is achieved by sliding an end portion of one tube of greater internal size than the other (the tubes may be of circular or rectilinear cross section) over the end of the other tube so that as the first set of latching means which is nearest the end of the first tube meets the recess of the other tube nearest its end they do not engage latchingly, latching engagement being only possible when the first set of latching

means is opposite to the first recess and second set opposite the second recess.

Means are preferably provided to unlatch the latching means from outside the tube connection. Such a means is a protrusion from each latching means to the outside which can be urged outwardly against the bias by suitably shaped ring around the connection.

A tubular connection according to another aspect of the invention comprises a first tube and a second tube, the first tube having a circumferential recess biased to latchingly engage with the recess by inward movement, the latching means being provided with means to cause outward unlatching movement so that by relative axial movement of the tubes they can be disconnected.

The provision of disconnection means when used underwater provides a simple way of disconnecting without the use of divers.

Embodiments of the invention will now be described by way of example with reference to the accompanying drawings in which:- Figure 1 is a cross section taken on A-A of Figure 2 of a tubular connection according to the invention, Figure 2 is a cross section of Figure 1 taken on B-B, Figure 3 is a cross section taken on A-A of Figure 2 of the connection of Figure 1 at a first engaging stage, Figure 4 is a similar cross section to Figure 3 showing the connection of Figure 1 at a second engaging stage, Figure 5 is a similar cross section to Figure 3 showing the connection of Figure 1 at a third engaging stage,

Figure 6 is a similar cross section to Figure 3 showing the connection of Figure 1 at a fourth and final engaging stage, Figure 7 is a cross section taken on D-D of Figure 6, Figure 8 is a cross section of a second embodiment of the invention taken on E-E of Figure 10, Figure 9 is a part cross section of one tubular member for the connection of Figure 8, Figure 10 is a cross section of Figure 8 taken on F-F, Figure 11 is an axial cross section of a third embodiment of the invention, Figure 12 is an axial cross section of a fourth embodiment of the invention, and Figures 13 and 14 are similar cross sections of a modification to the first embodiment of Figure 1 showing disengaging arrangements for the tubular connection of the invention.

Figure 15 is a similar longitudinal cross section to Figure 6 showing a fifth embodiment of the invention.

Figure 16 is a longitudinal cross section of one of the latching recesses of the embodiment of Figure 15.

Figure 17 is a transverse cross section of the recess of Figure 16 taken on XVII.

Figure 18 is a cross section of half a first tube of Figure 15 taken on XVII.

Figure 19 is a cross section of a second tube of Figure 15 taken on XIX, and Figure 20 is a partial longitudinal cross section of a further embodiment of the invention.

In the first embodiment shown in Figures 1 to 7, a first tube 2 of circular cross section is arranged to fit over a second tube 4 to form a connection as shown in Figure 6. The connection comprises two sets 5 and 6 of latching means 8, the first of which fits in a latchingly engageable manner into a first recess 10 whilst the second set fits into a second circumferential recess 12.

As will be seen from Figure 1, each set of latching means comprises eight latches 8 and 8'. Each latching member is supported on a resiliently flexible finger 14 and 14'. The fingers are intercollated so that, as seen in Figure 1, the downwardly extending fingers 14 which are fixed at their upper end 16 lie adjacent to the upwardly extending fingers 14'which are fixed at their lower end 18. Both sets of fingers 14 and 14'are pinned together for partial rotation at their mid point, or other intermediate position, that is, at the level of the cross section B-B on which Figure 2 is taken. By this means, outward pressure on latches 8'causes latches 8 to move outwards and vice versa.

On first engagement between tube 2 and tube 4, as shown in Figure 3, latches 8'of the second set 6 are forced outwardly by the end portion 20 of tube 4 until recess 10 is level with set 6 of latches 8'. The latches then tend under the bias of finger 14'to enter recess 10. This is shown in Figure 4. As the tube further intrudes into tube 2, a chamfered face 22'on each latch 8'causes latches 8'to ride outwardly from the rectilinear abutment face 241 ouf recess 10. This is shown in Figure 5. As tube 4 continues into tube 2, recess 10 comes opposite set 5 of latches 8 and at the same time, recess 12 comes opposite to latches 8'of set 6. Both sets 5 and 6 of

the latches are then able to engage in the recesses 10 and 12 so that the rectilinear abutment faces 24'and 24 of recesses 10 and 12 latchingly engage with rectilinear abutment faces 28 and 28'on latches 8 and 8'. Tube 4 is then latched into place in tube 2 so that any axial movement of tube 4 in either direction is transferred directly to tube 2.

Whereas the tubes are shown as having a circular cross section, they can equally be of rectangular cross section.

Each latch 8 or 8'has a guiding bolt 30 which is mounted for axial movement in radial openings 32 in tube 2. In a modification of this embodiment, as shown in Figures 13 and 14, the guiding bolts 32'for latches 8'have lengthened shanks which engage in arms 34 of cranked members 36 which pivot on abutments 38. In order to release the latches, and thus disengage the connection, a ring 40 surrounding the tube is lowered so as to cause cranks 36 to pivot about abutments 38 and so cause bolts 32'to move outwardly and hence latches 8' outwardly. Because the fingers 14'and latches 8'are fixed at point 48 to the fingers 14 of latches 8, latches 8 also move outwardly. Hence both sets 5 and 6 of the latches disengage from recesses 10 and 12. Tube 4 can then be pulled out of tube 2.

It will be appreciated that because the fingers 14 and 14'are interconnected only one set of bolts 32 on either set 5 or set 6 but not both is required.

Figures 8,9 and 10 show a second embodiment in which any torque between the tubes which might damage the fingers 14 and 14'is relieved by means of pointed blocks 50 on first tube 52 which engage on corresponding pointed blocks 53 on second tube 54. These are clearly shown separately in Figures 8 and 9 and mated together in Figure 10. Engagement between the tubes may be assisted by a proprietary guidance system 56.

In a third embodiment, shown in Figure 11, a single set of upwardly extending fingers 14'with latches 8'engage in a single recess 12'. The latches 8'have the same directional effect for acting in tension as the arrangements in Figure 1.

However, in order to enable the connection to act so as to counter movement in both directions, an external collar 70 on tube 4'engages with an internal ring 72 on tube 2'.

In a fourth embodiment, shown in Figure 12, the reverse arrangement of Figure 11 is shown with collar 70'on tube 4" acting with recess 10'to provide bidirectional latching.

An energy absorbing collar may be incorporated into the arrangement. This is shown in the embodiment of Figures 15 to 19 and comprises a ring 75 welded to a segmented liner 76 which is bonded to an elastomeric collar 77 formed for instance of polychloroperene. The elastomeric collar 77 is in turn bonded to the upper pile tube 79. The ring 75 is not attached to the pile tube 79, being free to move axially independently of the pile tube 79.

The energy absorbing collar arrangement of this latter embodiment is intended to absorb energy by deformation of the elastomeric liner 77 in the event that the pile is inadvertently overdriven. This occurs when the pile hammer operator allows the pile to penetrate beyond the target penetration. Before the lower pile groove abutment face 80 can be driven against the abutment face 81 of the latch or spring head 82, the ring 75 will engage on an upper support ring 84 which has a chamfered surface corresponding to the chamfered surface of ring 75. Further driving of the pile will cause ring 75 to react with the segmented liner 76, causing the elastomeric collar 77 to be deformed in shear. A gap 85 between the ring 75 and collar 77 enables the free deformation of the collar without the slip ring 75 bearing directly on to the collar 77. The ring 84 contacts ring 75 before abutment faces 80 and 81 come into contact. This ensures that energy applied to tube 79 will be absorbed by a combination of both

the collar shear deformation and the pile overcoming soil resistance to penetration. Furthermore, the avoidance of stress on the spring head 82 avoids damage to these components.

In Figure 16, the upper pile groove 86 is shown, and in broken lines, an upper spring head 87 is also shown. The abutment faces 89 and 90 of respectively the spring head and pile groove are inclined to the horizontal to ensure better engagement.

Because of the necessary gap between the outer surface 92 of the upper pile and the inner surface 93 of the springs 94 and 95, it is possible for the upper pile tube 79 to be inclined slightly to the lower pile tube 97. As a result of this, it would be possible to have an uneven distribution of loading to each of the spring heads 82 and possibly 87. To assist in avoiding this, the spring head abutment face 89 of spring head 87 and also spring head 82 are each provided with a nib 108 which, when the faces 89 and 90 come into engagement, bears against radial beads 99 on face 90, causing localised bearing deformation. The beads 99 are welded on to the face 90, using a soft material such as soft iron or possibly copper or a nickel alloy.

In order to ensure that outward movement of spring heads 87 results in a consequential outward movement of spring heads 82 to facilitate interlocking and unlocking of the tubes 79 and 97, the springs 94 which terminate with upper spring heads 87 are arranged to push out springs 95, having spring heads 82 by means of arcuate plates 100 welded to springs 95 in such a way as to overlap on each side the edges of springs 94. This is best shown in Figure 19. In order to balance the outward movement of spring heads 87 and spring heads 82, the arcuate plates 100 are located nearer heads 87 than heads 82, as may be seen in Figure 15.

In order to unlatch the pile tubes 79 and 97, retractor bolts 101 are provided which locate freely in radial holes in tube 97 but which are threadingly connected to the heads 87. Each

bolt 101 has an outer nut 102 to which is welded a large washer 103. The position of the spring head can be adjusted radially so as to avoid the lower edge 104 of the pile hitting the upper nose 105 of any of the upper spring heads during connection of the two pile tubes. The washer 103 also provides a visual indication for a remote underwater camera as to when the retractor bolts attached to the spring heads move radially inward to engage in groove 86. This is particularly useful when coupling piles underwater where any indication has to be easily visual to a remote camera.

To prevent soil or detritus from entering the annular space 106 between tubes 79 and 97, which could interfere with the operation of springs 94 and 95, an elastomeric seal 107 is provided on the inner side of a ring 108 on the upper end of lower pile tube 97 and seals against the outer face of tube 79.

It will be appreciated that the lower pile tube 97 fills with soil as it is driven into the ground or sea bottom.

The operation of the embodiment shown in Figures 15 to 19 is similar to that shown in Figures 1 to 7. It will be appreciated that retractor bolts can be provided on the lower spring heads 82. In this case additional arcuate plates 100 would be welded to springs 94 to ensure consequential movement of upper spring heads 87. It is also possible to use other methods of connecting the springs 94 and 95 together. For instance, coiled springs acting on the inner and outer surfaces of both springs 94 and 95 could result in suitable functional connection although these might not be so reliable as the arcuate plate construction shown in Figure 19.

In Figure 20, an arrangement similar to Figure 12 is shown, in which an upper tube 110 is to be fitted to a lower tube 112, having a cruciform head 113. The cruciform head 113 is formed from two upwardly tapering plates 114 and 115 interlocked to provide a virtually conical mating head to assist location of upper tube 110. Plates 114 and 115 are mounted to a collar 116 having a lower abutment surface 117 to which spring heads 118

engage to lock the pile tubes together. Abutment between tubes is here provided by end surfaces 119 and 120 of tubes 112 and 110 respectively. A flange plate 122 is welded to the lower end of tube 110 adjacent surface 120 in order to strengthen the tube 110 at its outer and lower edge. Retractor bolts 123 are fixed to the spring heads 118 as before or by the simple means as shown with the bolt heads in the spring heads and the nuts bearing on the outside of tube 110.

The connection arrangement of the invention is primarily intended for subsea surface piling but may well have surface and shore applications. The invention is useful for connecting piles and pile sleeves together but also can be used for connecting one pile axially to another.