Abstract:
A method and apparatus for connecting two pieces of pipe having flanges when the pipe pieces are located deep under a water surface. A movable bolt wrench is provided which has a number of wrenches mounted in a frame corresponding to the bolt holes on the flanges of the pipe pieces. Bolts located in the bolt wrenches are aligned with the bolt holes of the flanges and inserted into the bolt holes. A nut wrench is also provided containing nuts which, when aligned, are threaded onto the ends of the bolts associated with the bolt wrench. After the bolt and nut connections are made, these bolts and nuts are tightened by the operation of the bolt and nut wrenches.

Description:
BRIEF SUMMARY OF THE INVENTION 
     In order to enable the realization of nut and bolt connections, in particular deep under the water surface, the invention provides a method herein described in addition to an apparatus also herein described. The invention also provides a bolt designed specially for the application of the invented method. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     In the drawings: 
     FIGS. 1-8 show successive steps of the underwater displacement of a pipe piece; 
     FIGS. 9 and 10 show respectively a top and side view of an apparatus according to the invention; 
     FIG. 11 shows a nut magazine; 
     FIGS. 12 and 14 show side views of a preferred embodiment of the apparatus according to the invention in successive method steps; 
     FIGS. 13 and 15 show a partial top view of FIGS. 12 and 14 respectively; 
     FIG. 16 shows a partial exploded view of FIG. 10 showing the area labeled XVI of FIG. 10; 
     FIG. 17 shows a partial exploded sectional view of FIG. 16 showing the area labeled XVII of FIG. 16; 
     FIGS. 18 and 19 show views of partial exploded views of FIG. 14 showing the area labeled XIX of FIG.  14 . 
     FIG. 20 shows a partial cross-sectional front view of a preferred embodiment of the apparatus of the present invention; 
     FIGS. 21 and 22 show an exploded partial elevation and side view of FIG. 10 showing area XXI of FIG. 10; 
     FIG. 23 shows a section along the line XXIII—XXIII of FIG. 22 on larger scale; 
     FIG. 24 shows a partial exploded view of FIG. 17 showing area XXIV of FIG. 17; 
     FIG. 25 shows a section corresponding with FIG. 20 relating to a preferred embodiment of the apparatus according to the invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     In the method according to the invention, for instance two pipe pieces  100  which lie on a seabed  101  at a depth of for instance 1 km are displaced by means of yokes  106  (FIGS. 1-8) such that they come to lie mutually in line and mutually connect with their flanges  102 . One yoke  106  at a time is herein placed horizontally by means of its telescopic legs  103  provided with pivoting feet  105  (FIGS. 1,  2 ). A gripper frame  104  is displaced in transverse direction of pipe pieces  100  relative to yoke  106  by means of hydraulic cylinders  107  to a position above a pipe piece  100 . Then the yoke  106  is moved downward, a gripper  108  supported by gripper frame  104  is closed round pipe piece  100  by means of a cylinder  109  and yoke  106  with pipe piece  100  is raised, whereafter pipe piece  100  is displaced. 
     These operations can be repeated, optionally while yoke  106  is moved in longitudinal direction of feet  105  and pipe piece  100  by means of hydraulic cylinders  110  (FIG.  9 ). 
     When pipe pieces  100  lie mutually in line, which is controlled from a Remote Operated Vehicle (ROV)  111  (FIG.  10 ), a positioning frame  112  lowered from a ship is placed above a pipe piece  100  on legs  113 . Positioning frame  112  transports a nut wrench  2  and a bolt wrench  3  which are placed on pipe pieces  100 . Positioning frame  112  further carries pump means for hydraulic fluid for driving the diverse hydraulic motors of wrenches  2  and  3 . 
     Nut wrench  2  comprises an upper half  115  of a nut magazine  4  which is fixedly mounted on a wrench frame  114  and from which two lower quarters  116  are suspended by means of cylinders  117  for swivelling between the opened position of FIG. 11 and a closed position engaging round a pipe piece  100 . Wrench frame  114  is supported on a pipe piece  100  via a saddle  118 . Nut magazine  4  has for instance  16  compartments  5  distributed over the periphery and having a hexagonal profile, in each of which compartments is received one nut  6  which is urged outward by a spring  119  but which is held so rigidly in its closely dimensioned compartment  5  by means of rubber friction rings  120  (FIGS. 18,  19 ) that spring  119  cannot overcome this friction. 
     The bolt wrench  3  (FIG. 16) comprises a wrench frame  121  which is provided with floater bodies  122  and which is lowered onto a pipe piece  100  by means of a saddle  123 . A saddle-shaped supporting head  124  is slidable in axial direction relative to saddle  123  by means of hydraulic cylinders  125 . Saddle  123  can be anchored to a pipe piece  100  by means of hydraulically energized transverse pins  47 . A frame  133  mounted to supporting head  124  by means of a ring bearing  127  is rotated into an angular position by means of a gear ring  128  and driving gear  129  such that four wrenches  30  mounted on frame  126  and disposed in each case at mutual angular distances of  900  are situated opposite bolt holes  8  of flanges  102 . The supporting head  124  is then displaced relative to wrench frame  121  until the bolts  9  protrude into bolt holes  8 . Displacing of supporting head  124  is measured by means of a wire  49  trained round a pick-up  48 . In order to place bolt holes  8  of flanges  102  in line, the pipe pieces  100  are optionally twisted slightly by pivoting the yokes  106  (in which pipe pieces  100  are held) relative to each other using pipe pieces  100  as pivot axis. 
     Together with wrench frame  114 , nut magazine  4  is moved relative to saddle  118  toward bolts  8  by means of hydraulic cylinders  130  (FIGS. 14,  15 ) until a positioning cavity  131  of nut magazine  4  strikes against a positioning pin  132  of a flange  102 . The compartments  5  with nuts  6  are hereby centered relative to bolt holes  8 . Bolts  9  drive nuts  6  inside counter to spring action, whereby the friction of rings  120  is overcome. 
     Each wrench  30  comprises in a housing  7  a socket  32  which is urged by means of a spring  34  into the position shown in FIG. 17 on a nut  35  and which is driven by a hydromotor  40  via its gear ring  37  and toothed wheels  38 ,  39 . Each screw bolt  9  has a protruding grooved end  62  and a fixed ring  63  at a small distance from nut  35 . Present is FIG. 17 at the free end of the grooved end  62  is a welded clamp  64  consisting of a number of, for instance three, clamping pieces  65  which have conical surfaces  67  and  68 . Surfaces  67  co-act with the conical surface  73  of a piston  69  of a double-action cylinder  70  which is fixed by means of bolts  66  to a piston piece  61 . Surfaces  68  co-act with a conical surface  73  of the piston piece  61  of piston  74  of a hydraulic, double-action cylinder  72 . Clamping pieces  65  are urged apart by tangential pressure springs  75  arranged in each case in each separating surface. 
     Piston  69  carries a bolt  77  which in the clamping position of clamping pieces  65  (also the clamping position of piston  69 ) lies opposite an electrical sensor  78  mounted on cylinder  70  and thus indicates the clamping position. 
     The ring  63  fixed for instance by glueing or locking comprises axial pins  81  which are urged away from nut  35  against stops  85  by springs  80  and received in continuous holes  83  and which, when energized by sliding sleeve  87  moves into arcuate recesses  89  of nut  35  (FIGS. 17,  24 ). 
     Piston  74  is sealed with at least one sealing ring relative to sliding sleeve  87  which is guided over threaded end  62  by means of a plastic lining  88 . 
     Piston  74  is locked against rotation by means of axial rods  96 . 
     During insertion of bolts  9  into flanges  102  (FIG. 12) the clamps  64  are closed and the pins  81  of fixed ring  63  engage into nut  35 . 
     During arranging of nuts  6  (FIG. 14) clamps  64  are disengaged from bolts  9  and nuts  35  are driven by means of sockets  32  and motors  40  in order to rotate the bolts  9  which are coupled to nuts  35  via pins  81  and fixed rings  63  and thus screw them into the nuts  6 . 
     When nuts  6  are screwed against a flange  102  the supporting head  124 , and thus also housings  7 , are moved away from flanges  102  by means of cylinders  125  so that the fixed rings  63  are moved away from nuts  35  and the disengaged nuts  35  move toward flanges  102  with further driving by motors  40 . 
     While bolts  9  are held fast by clamps  64  and cylinders  72  are energized to place bolts  9  under axial tension, nuts  35  are driven by means of motors  40  in order to screw the flanges  102  firmly against each other. 
     After release of clamps  64  the bolt wrench  3  can be removed, four other bolts  9  can be placed therein by means of the ROV and these can be inserted into flanges  102  in a different angular position of ring bearing  127  relative to supporting head  124 . 
     Instead of using a nut wrench  2  a flange  102  can be provided at each bolt hole  8  with a nut compartment  10  mounted thereon (FIG. 20) in which is situated a nut  6  urged toward flange  102  by a spring  119 . 
     Although the described hydraulically driven clamp  64  is recommended, another, for instance mechanically driven, clamp can also be used. 
     A nut wrench  12  as shown in FIGS. 21-23 of the drawings can be used as an alternate embodiment of the invention to connect or disconnect the pipe pieces. The wrench frame  13  thereof is placed on a pipe piece  100  by means of two saddles  14  and  15  which can each be clamped fixedly to pipe piece  100  by means of a hydraulically operated transverse pin  16  respectively  17 . By fixedly clamping the saddle  14  displaceable relative to wrench frame  13  to pipe piece  100 , the wrench frame  13  can be displaced relative to saddle  14  and, conversely, in the case of a fixedly clamped saddle  15  the saddle  14  is forward displaceable in order to perform the required step movements. (Wrench frame  14  of FIG. 12 is also displaceable in the same manner). 
     The zero position of the angular displacement can be realized by means of a V-shaped angle section  22  which co-acts with a pin  23  welded to pipe piece  100 . Because the weight of nut wrench  12  is compensated by a floater body  24 , nut wrench  12  can be swivelled slightly relative to pipe piece  100  by means of the ROV. 
     A tool head  18  can be set in the required angular position by means of a ring bearing  25  mounted thereon, a gear ring  19  and a driving gear  20 , wherein a plurality of, for instance four, nut wrenches  21  lie in line with bolt holes  8 . 
     Each wrench  21  comprises a housing  26  and a nut magazine  27  mounted rotatably and a slidably therein and urged toward flange  102  by a spring  28 , which magazine is adapted to receive a plurality of, for instance four, nuts  6  (FIGS.  18 ,  19 ) and has for this purpose a hexagonal internal profile. Nut magazine  27  is driven via its gear ring  29  and a driving gear  31 . 
     Hydraulic motors are present for the diverse drives. 
     Nut magazine  27  contains a push member  41  which is provided with three L-shaped leaf springs  42  which in the return direction act as pins, in addition to a rubber friction ring  43 . When tool head  18  is in its starting position, the saddle  15  has axially in line with nut magazine  27  a pusher  44  which in each case is driven by a cylinder  45  and which shifts by one nut width at a time the push member  41  and the nuts  6  which are present. 
     In combination with this wrench  21  a wrench  46  is used in each case which is identical to wrench  30 , except that the now superfluous fixed ring  63  is preferably omitted. Bolts  9  are inserted into holes  8 , a nut  6  is screwed on in each case, a nut  35  is screwed in each case against a flange  102 , bolts  9  are tightened by energizing cylinder  72  and nut  35  is screwed further to flange  102 , all of this while the bolts  9  in question are held fast by means of clamps  64 . Clamps  64  are thereafter released to remove wrenches  126  from bolts  9 . 
     Wrenches  126  are once again filled with bolts  9  by means of the ROV and these are inserted into other holes  8  when wrenches  126  are swivelled through an angle, whereafter nuts  6  from nut wrenches  21  are screwed thereon from the other side. 
     In order to hold nuts  6  positioned in their compartment, instead of friction rings  120  on the nuts  6  rubber strips can be arranged on the inner walls of nut compartments  5 , for instance in the middle of the hexagons in axial direction of nuts  6 , which strips bring about a considerable friction between nuts  6  and the inner walls of compartments  5 . 
     If only one nut and bolt connection has to be made, for instance because a bolt  9  must be replaced, the same wrench  3  can be used, wherein only one of the wrenches  6  is then driven. Control and driving of each wrench is dependent on the others for this purpose.