Abstract:
The invention concerns an annular clamping ring in particular for laying oil ducts including a rigid annular base ( 2 ) supporting with support apparatus a coaxial ring-shaped assembly of vertical jaws ( 4 ) mobile in the diametral planes; said apparatus includes long connecting rods ( 14 ) articulated on the base ( 2 ) and on the outside of the jaws ( 4 ) in an almost vertical position, and the rigid annular body ( 3 ) enclosing the jaw ( 4 ) assembly, mobile in vertical translation by means of controllable cylinder actuators ( 6 ) linking it to the base ( 2 ); the jaws ( 4 ) are linked with the annular body ( 3 ) by at least two connecting rods ( 5 ) forming an articulated parallelogram, such that the annular body ( 3 ) vertical displacement relative to the base ( 2 ) causes a substantially radial and synchronized displacement of the jaw assembly ( 4 ).

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a clamping ring (otherwise known as a clamp) of large size, particularly intended, by clamping, to hold a rigid or flexible oil duct or a similar heavy cylindrical elongate element (tube, cable, umbilical) and which is designed, in particular, to be used in a device for laying tubular ducts under water from a laying vessel. 
     French Patent Application No. 98/00148 in the name of the Applicant Company, to which reference can usefully be made, and the teaching of which is incorporated herein by reference, discloses a duct-laying device of the family of J-lay devices. It comprises an inclinable tower, placed in and a great height above the moon pool of the laying vessel, and designed to take a certain length of duct that is to be laid, and means for holding and shifting the said length of duct; the said means comprise two motorized mobile carriages capable of travelling the said height of the tower, and able to take members for holding the duct. These holding members are very advantageously clamping jaws (otherwise known as clamps), that is to say actual (and static) clamping devices, as opposed in particular to linear caterpillar-type tensioners (which entail moving the duct along at the same time as the clamping jaws) By controlling the tightening of the clamps and the displacement of one or other of the carriages along the tower, it is possible to use the device described in the aforementioned application in a great many possible configurations, giving the device great versatility, in order to move the duct along in what is known as the hand over hand fashion. 
     Document GB 2,299,646 discloses a clamp with jaws borne by connecting rods in the form of an articulated parallelogram, in accordance with the preamble of the appended Claim 1. However, in this device which is intended to keep a duct horizontal, the movement of the jaws is essentially longitudinal and is ill-suited to the problem at which the invention is aimed, namely that of holding heavy vertical ducts. 
     BRIEF SUMMARY OF THE INVENTION 
     The object of the invention is to provide a clamp which is particularly well suited to this context. 
     The object of the invention is achieved by virtue of an annular clamping ring comprising a rigid annular base which has an axis, and supporting, by support means, a coaxial ring-shaped assembly of jaws parallel to the axis and mobile in diametral planes, the said support means comprising, on the one hand, a rigid annular body surrounding the assembly of jaws, mobile in axial translation by means of controllable cylinder actuators which connect it to the base, the jaws being connected to the annular body by at least two connecting rods forming an articulated parallelogram, characterized in that the said support means also comprise long connecting rods articulated on the base and on the outside of the jaws in a position which is almost the axial direction, such that the axial translation of the annular body with respect to the base causes a substantially radial and synchronized displacement of the assembly of jaws. 
     Advantageously, each of the jaws consists of a main jaw which consists of a main beam and of a secondary jaw which consists of an adapter girder mounted on the main beam at a distance away that can be altered between at least two positions, which makes it possible to increase the range of duct diameters that can be accommodated. As a preference, the adjustment of the distance may differ from one girder to the next or from one group of girders to the next, so that a lower number of girders can be used for ducts of small diameter. 
     This diversity is further enhanced if the adapter girders are chosen from sets of several sizes. 
     Advantageously, provision is made in the base and the body of the clamp for a sector, thus constituting a doorway which can advantageously be locked, for slipping a duct in sideways or for inspection. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will be better understood by virtue of the following description of one particular embodiment, referring to the appended drawings in which: 
     FIG. 1 is a view from above of the clamp of the invention, 
     FIG. 2 is a view from above of the same clamp, with the lateral doorway open, 
     FIG. 3 is a view in section on III—III of the clamp of FIG. 1, 
     FIG. 4 is a view in section on IV—IV of the clamp of FIG. 1, the left-hand half section depicting the clamp in the closed position (clamping position), while the right-hand half section depicts it in the open position (released position), 
     FIGS. 5A,  5 B and  5 C are views respectively from the side, from the front and from above of a jaw vertical main beam, 
     FIGS. 6A,  6 B and  6 C are views respectively from the side, from the front and from above of a jaw adapter girder, 
     FIGS. 7A and 7C are views respectively from the side and from above of a beam and of a girder of FIGS. 5 and 6, associated in the deployed position, 
     FIGS.  7 ′A and  7 ′C are views respectively from the side and from above of a beam and of a girder of FIGS. 5 and 6, associated in the close-together position, 
     FIGS. 8A and 8B are diagrammatic views respectively from the side and from above of a clamp of the invention, with jaws with an adapter girder of a first type, clamping a duct of a first diameter, 
     FIGS. 9A,  9 B,  10 A and  10 B are views similar to FIGS. 8A and 8B for, respectively, ducts of a second, third diameter and the same jaws, 
     FIGS. 11A,  11 B,  12 A and  12 B on the one hand, and  13 A and  13 B on the other hand, are views similar to the preceding figures for, respectively, ducts of a fourth and fifth diameter with a second type of jaws, and of a sixth diameter with the same second type of jaws, only one in three of which is in the deployed position, 
     FIG. 14 is a side view of the constructional detail of the base of the clamp, in the region of its opening, 
     FIG. 15 is a detail view from above of the clevis joint articulating a jaw control connecting rod, 
     FIG. 16 is a diagrammatic view from above of a clamp according to the invention, mounted in a duct-laying tower which is depicted in broken line. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Reference is made first of all to FIGS. 1 to  4 . The clamp  1  of the invention is essentially made up of a rigid annular base  2 , about 5 m in diameter, supporting a clamp body  3  about 4 m high, mobile vertically, on which twelve jaws  4 , also about 4 m high, are mounted via four parallel articulated connecting rods  5  about 1.6 m long, keeping the jaws  4  vertical. 
     The base  2  consists of an annular beam structure leaving, at the centre, an orifice  57  for the passage of a duct of about 1.6 m diameter. Fixed to the annular structure, distributed about the circumference, are the bodies of twelve vertical hydraulic cylinder actuators  6 , the top ends of the rod  7  of which are articulated in clevis joints  8  secured to the clamp body  3 . 
     The clamp body  3  consists of a cylindrical (or polygonal for the convenience of producing it in twelve assembled sectors) rigid structure which, on its inner surface, apart from the clevis joints  8  already mentioned, has the articulation supports  9  intended for the clevis joint-shaped bottom ends  10  of the connecting rods  5  connected to the jaws  4 . FIG. 15 shows in greater detail the articulation of the clevis joint  10  at the bottom of the connecting rod  5  to an axle  20  passing through the support  9 . 
     The connecting rods  5  are produced in the form of rigid tubes, the top ends  11  of which are also shaped as clevis joints, so that they can be articulated about axles  21  passing through four vertically aligned holes  22  in the jaws  4 , as illustrated in FIGS. 5 to  7  to which reference is now made. The jaws  4  consist of vertical beams  23  lined, on the inside, by a mobile adapter girder  12  articulated to the beam  23  by link rods  24  and  24 ′. 
     Each beam  23  comprises a section piece  25  of essentially rectangular cross section extended, on its radially interior face (with respect to its position in the circular clamp) by two triangular profiled flanges  26  which leave between them a vertical space  27  of essentially U-shaped cross section, the closed end of which is formed by the radially interior face  29  of the piece  25 . This face  29  is crenelated with successive merlons  30  comprising an oblique flank  31  and a straight flank  32 , flanking a flat top  33 , two merlons  30  being separated by a crenel  40  with a flat bottom  34 . 
     Each adapter girder  12  consists of a section piece of essentially rectangular cross section, the thickness of which essentially corresponds to the width of the space  27  in which it is intended to be inserted, and the length of which may be chosen according to the diameters of the ducts that are to be clamped within a certain range. On the radially interior side of the girder  12 , the edges form chamfers  35  inclined at 15° with respect to the vertical mid-plane  36  of the section piece and parallel to the oblique faces  37  of the flanges  26 . The radially exterior face of the girder  12  consists of merlons  39  which complement the crenels  40  of the section piece  25 . Likewise, the crenels  41  separating the merlons  39  complement the merlons  30 . 
     In the thickness of three merlons  39  of the girder  12 , advantageously one at the top, one near the middle and one near the bottom of the girder, there is a recess  42 , the vertical walls of which are pierced with an orifice  43  for the passage of an axle allowing one end of the link rods  24  and  24 ′ to be articulated. The other end of the link rods  24  and an intermediate region of the link rod  24 ′ is articulated in the same way to an axle  44  fixed into the walls of recesses  45  formed in corresponding merlons  30  belonging to the beam  23 . The width and shape of the recesses  42  and  45  allows the passage and necessary pivoting of the link rods  24  and  24 ′. The lower recess  44 ′ differs from the top and middle two recesses  45  in that it is extended towards the bottom of the section piece and is also extended radially outwards by a manoeuvring cavity  46  actually inside the section piece  25 . 
     The cavity  46  is intended to house, on the one hand, a continuation  47  of the lower link rod  24 ′ and, on the other hand, the rod  48  and the top end  49  of a cylinder actuator  50 , the body of which is arranged under the beam  4 . The lower link rod  24 ′ comprises, on the one hand, a part identical in terms of dimensions to the link rods  24  and articulated in the same way on the axles  43  and  44  and, on the other hand, beyond the articulation at  44 , the rigid continuation  47  has a longitudinal slot  51  in which the articulation axle  52  for the top end  49  of the cylinder actuator  50  slides. 
     In the retracted position depicted in FIGS. 7A and 7C, the rod  48  of the cylinder actuator  50  is retracted and has forced the link rod  24 ′ to pivot completely so as to bring the axle  43  into the highest possible position; the collection of link rods  24  and  24 ′ has pivoted at the same time and has placed the girder  12 , still vertical, in its highest position in which, because of the way in which the merlons and crenels provided, on the one hand, on the beam  23  and, on the other hand, on the girder  12  fully complement each other, has fully engaged in the space  27 , and is therefore fully housed between the flanges  26  of the beam  23 . The fitting-together of the merlons and crenels of the beam and of the girder ensures that the vertical forces exerted by one element on the other are fully reacted. The oblique flank  31  and the corresponding oblique flank on the complementary element, allow the link rods to pivot and the fitted-together parts to disengage. In addition, the horizontal components of forces resulting from the weight of a duct (sketched in as  100 ) applied to the girder and tending to part the two elements because of the obliqueness of the contacting flanks are countered, on the one hand, by the friction of the two flanks one on the other and the position-maintaining force of the cylinder actuator  50  and, on the other hand, by the physical impossibility of parting the two elements from one another, the beam  23  being blocked radially on the outside by the rest of the structure of the clamp and the girder  12  being blocked radially on the inside by the duct  100  against which it actually rests. The resulting end effect is an improvement in the clamping force. 
     In the deployed position depicted in FIGS.  7 ′A and  7 ′C, the rod  48  of the cylinder actuator  50  is deployed, and has caused the link rod  24 ′ to pivot so that the axle  23 , at the end of its circular path, reaches it lowermost point In this position, the girder  12  rests via its merlons  39  on the merlons  30  of the beam  23 , and protrudes from the flanges  26  as shown in FIG.  7 ′C. The weight of a duct (sketched in as  100 ) in contact with the girders  12  tends to press the girder all the more firmly against the beam, because the axles  43  of the link rods  24  and  24 ′ are located below the axles  44 . Deploying or retracting the adapter girders makes it possible to create a 9 cm difference with respect to the axis of the clamp (namely an 18 cm difference in diameter for a duct held in the clamp). 
     The beam  23  comprises the four aforementioned aligned axle holes  22  and, radially towards the outside and towards the top of the beam  23 , a lug  13  houses the axle  53  articulating the top ends of twelve long connecting rods  14  (about 4.8 m long), which are almost vertical, the bottom end of which is articulated at  15  to the base  2  (cf. FIGS.  3  and  4 ). 
     By comparing the right-hand and left-hand halves of FIG. 4, it can be seen that deploying the rod of the cylinder actuator  6  raises the clevis joint  8  and the entire body  3  (left-hand half); the jaws  4 , held from behind by the articulation  53 , are not free to rise up at the same time as the body  3 ; a relative rotation of the connecting rods  5  about their articulations on the axles  20  thus occurs, the connecting rods  5  adopting a more horizontal position (for example between 7 and 22° to the horizontal in the clamping position). As the body  3  is a fixed distance away from the central axis  56  of the clamp, this results in the jaws  4  moving closer to the central axis  56 , corresponding to the clamping of the duct which may have been placed in the clamp  1 . During this movement towards the axis, the jaw  4  remains vertical because of the articulated parallelogram system consisting of the connecting rods  5 , and its heightwise position has varied only very slightly, because of the slight rotation of the long almost vertical connecting rod  14  providing the connection to the base  2 . Considering the base  2  as reference, and assuming that a duct against which the jaws  4  are clamped transmits its weight to these jaws, it can be seen that the resulting forces on the jaws  4  which tend to push these jaws downwards tend at the same time to move them closer to the axis  56  because of the articulation imposed by the connecting rods  14  connected to the fixed base, and therefore tend to clamp the duct more firmly. 
     In the right-hand half of FIG. 4, total retraction of the cylinder actuator  6  has placed the body  3  in its lowermost position and caused the connecting rods  5  to pivot, relative to the body  3 , into their most nearly vertical position (52° to the horizontal), which has had the result of placing the jaw  4  in its position furthest from the central axis  56 , that is to say in the position in which the clamp is the widest open. In this position, the separation between the jaws is identical to the diameter of the opening  57  of the base  2 . 
     The base  2  and the body  3  can open over a large enough angular sector to allow a duct to be slipped into the clamp, and for example may form a passage  58  measuring about 0.8 m as depicted in FIG.  2 . The opening is achieved by pivoting a sector about an articulation  16  using a manoeuvring cylinder actuator  17 . Closure and locking are performed at an annular part  18  collaborating with locking actuators  19  (cf. FIGS.  2  and  4 ). At the edges of the pivoting angular sector, the base  2  has overlapping joints  55 . 
     The clamp  1  according to the invention can be installed as shown in FIG. 16 in a carriage  60  with motorized wheels  61 , itself mounted in a duct-laying tower  62  (cf. the aforementioned Patent Application 98/00148). The clamp can also be mounted on any other hand over hand displacement system known per se. 
     Naturally, a hydraulic control unit, not depicted, is provided for powering the various hydraulic cylinder actuators of the clamp. 
     The way in which the clamp  1  works for clamping ducts of different diameters will now be explained with more particular reference to FIGS. 8 to  13 . To allow the clamp of the invention to adapt to suit the various diameters of pipe, the following features are combined appropriately: firstly, the various dimensions of jaw adapter girders  12 , secondly, the deployment or retraction of the said adapter girders into the jaw main beams (if appropriate, independently from one girder to another), and thirdly, naturally, the adjustment of the jaw separation by virtue of the controlled rise or fall of the clamp body  3  and by virtue of the movement of the various connecting rods  5  and  14 . 
     FIGS. 8A,  8 B,  9 A,  9 B,  10 A, and  10 B show the use of a clamp in which the adapter girders  12  of the jaws  4  are of the smallest size (the one also illustrated in FIGS. 7A,  7 C,  7 ′A, and  7 ′C), for which the girders  12  lie completely between the flanges  26  of the beams  23  when the jaws are in the retracted position. In FIGS. 8A and 8B, the clamp is clamping a duct  100  of a diameter of 0.22 m. The cylinder actuators  6  are deployed to their maximum extent and the connecting rods  5  are at their minimum angle of inclination α to the horizontal (7°). The cylinder actuators  50  of the jaws are in the deployed position as shown by the inclination of the link rod  24 ′ and the deployed position of the girders  12  with respect to the beams  23  of the jaws. As shown by FIG. 8B, the chamfered flanges  26  of the beams  23 , on the one hand, and the chamfered edges of the girders  12 , on the other hand, can come very close to one another when clamped around a duct. The separation e between two adjacent flanges is about 13 mm. 
     In FIGS. 9A and 9B, the only change is that the cylinder actuators  50  have been retracted and the girders  12  have therefore been retracted into the recess of the beams  23 , thus gaining, in terms of diameter, two lots of 90 mm, that is to say allowing the clamping of a duct with a diameter Ø of 0.4 m. 
     To change to the configuration of FIGS. 10A and 10B, the cylinder actuators  6  have been retracted a little and the body  3  thus lowered, to give the connecting rods  5  a clamping angle α of 22°, and allowing the clamping of a duct  100  with a diameter Ø equal to 0.6 m. The separation e between the adjacent flanges  26  of the jaws is 67 mm. 
     In FIGS. 11A to  12 B, use is made of a second size of adapter girders  12  which, even in the non-deployed position as shown by the position of the link rods  24 ′ in FIGS. 11A and 12A, protrude from the flanges  26  of the beams as can be clearly seen in FIGS. 11B and 12B. In the case of FIGS. 11A and 11B, the angle α is 7°, the diameter Ø0.2 m and the separation e 14 mm. In the case of FIGS. 12A and 12B, the angle α is 20°, the diameter Ø0.39 m and the separation e 66 mm. It can thus be seen that in this configuration ducts with the same diameter as the configuration of FIGS. 9A and 9B can be clamped. 
     In FIGS. 13A and 13B, use has been made of the same size of girders  12 , but with just four of them in the deployed position, these thus being able to clamp a duct of very small diameter (Ø=0.08 m), the eight remaining girders being in the retracted position in order not to impede the extreme moving-together of the four deployed girders.