Abstract:
A connector for a hydrocarbon system includes a first duct section, a first connector part slidably attached to the first duct section for connecting to a complementary connector part attached to a second duct section and a retraction member for moving the first connector part in an axial direction between an extended position and a retracted position.

Description:
BACKGROUND OF THE INVENTION 
     The invention relates to a connector for a hydrocarbon system. 
     DESCRIPTION OF THE RELATED ART 
     In offshore applications, Floating Production Storage and Offloading systems (FPSO&#39;S) are moored to the sea bed via a riser supporting buoy which is locked into a conical cavity at the bottom of a turret. The turret is rotatably supported in a moonpool of the vessel and is releasably connected to the riser supporting buoy. Risers extend from a subsea hydrocarbon well to the buoy and via the buoy to piping in the turret. On the turret, a swivel stacks connects the stationary fluid ducts in the turret to fluid ducts on the vessel such as to be able to rotate in relation to the stationary risers together with the weathervaning vessel. Anchor lines are attached to the buoy for mooring the vessel in position. 
     In case of severe weather conditions, the mooring buoy is released from the vessel and sinks to a predetermined depth below the wave active zone. Upon reconnection, the buoy is hauled into the cavity of the FPSO and is locked into place. When the riser termination ends are aligned with the piping on the vessel, the risers can be connected to the piping and hydrocarbons can be supplied from the subsea well via the risers, the piping in the turret to the processing or storage facilities on the vessel. 
     SUMMARY OF THE INVENTION 
     It is an object of the invention to provide a connector of compact construction which can rapidly and reliably connect two hydrocarbon ducts. It is in particular an object of the invention to provide a connector which can rapidly and reliably connect hydrocarbon ducts on a riser supporting buoy to ducts on a turret in a receiving cavity. 
     Hereto a connector in accordance with the invention comprises a first duct section, a first connector part slidably attached to said first duct section for connecting to a complementary connector part attached to a second duct section and a retraction member for moving the first connector part in an axial direction between an extended position and a retracted position. 
     The ducts according to the invention can be brought into close mutual proximity and aligned for connection and can then be placed in a fixed position. Thereafter, the retraction member can be activated to axially extend one connector part to mate with the complementary connector part and to establish a fluid connection between the ducts. Since the alignment of the ducts takes place while these ducts are at a sufficient mutual distance, the risk of collision of the ducts and consequent damage is reduced. 
     The connector according to the invention may in one embodiment comprise a generally T-shaped core having a cylindrical part, a transverse part and a central channel connected to the first duct section for transport of hydrocarbons, a sleeve slidably around the core, having an upper and a lower transverse wall part contacting the core, a longitudinal wall extending between the transverse wall parts and defining at a lower end a tapering cavity for receiving a frusto-conical coupling head of the second connector part, at least one fluid pressure actuating member being connected with one end to the sleeve and with an other end to the core. 
     The connector is of compact design and can be fitted in the top part of the receiving cavity of the vessel. The sliding sleeve provides a relatively small size mechanically robust and liquid tight coupling. A valve assembly, for instance a double block and bleed ball valve, may be incorporated in each duct part, near a respective connector part in a compact design. 
     In an advantageous embodiment, a sealing ring is provided around the core between the transverse wall parts. When the sealing ring is pressed against the transverse part of the T-shaped core in the connected state, an effective seal is established preventing leakage of fluid along the outer surface of the cylindrical part of the core. A double barrier can be provided by a second seal at an outer surface of the lower transverse wall part for contacting the coupling head of the second connector part. 
     In a further embodiment the first connector means comprises a locking member attached to a lower part of the sleeve, movable in a direction transversely to the axial direction, having a pin extending through an opening in the longitudinal wall, the coupling head of the second connector part comprising a groove for engaging with the pin. 
     The locking member is of a relatively simple and compact design and maintains the ducts in a fluid tight relationship even under the influence of external forces, for instance wave-induced heave motions. In case of an emergency release the locking pins can be rapidly retracted to uncouple the duct sections on the vessel from those on the buoy. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING FIGURES 
       Some embodiments of a connector in accordance with the invention will be explained in detail with reference to the accompanying drawings. In the drawings: 
         FIG. 1  shows a partly cross-sectional view of a FPSO comprising a riser-supporting buoy and a connector according to the invention, 
         FIG. 2  shows the interconnected fluid ducts at the top part of the buoy on an enlarged scale, and 
         FIGS. 3   a  and  3   b  show the connector parts in their connected and disconnected state, respectively. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  shows a hydrocarbon production vessel (FPSO)  3  anchored to the sea bed via anchor lines  10  that are attached to a riser supporting buoy  11 . The riser-supporting buoy  11  is connected to a conical cavity  1  at the bottom of a turret  2  and is locked to the vessel via locking member  6 . The vessel  3  can weathervane around the turret  2  to align itself with prevailing wind and current conditions. Risers  12  extend from a sub sea hydrocarbon well to the riser-supporting buoy  11  and are guided through tubes  14  in the buoy to an end connector  15  near the top  16  of the buoy  11 . The end connectors  15  are detachably connected to hydrocarbon ducts  17  on the turret, which ducts  17  connect to swivels  8  and via those swivels to ducts on the vessel  3 . 
     Upon detaching of the buoy  11 , for instance in case of severe weather conditions, the connector  15  is released and the risers  12  can be lowered together with the buoy  11  to a desired depth below the wave active zone. 
       FIG. 2  shows the riser supporting buoy  11  and the connector  15  on an enlarged scale. The connector  15  comprises a first connector part  20  attached to upper duct section  21  and a second connector part  22  attached to lower duct section  23 . The first connector part  20  comprises a retractable section attached to retraction member  25 , for instance hydraulic cylinders, for movement of the retractable connector section in the axial direction (i.e. the length direction of the ducts  17 ). 
       FIG. 3   a  shows the connector parts  20 ,  22  in their connected position. The first connector part  20  comprises a T-shaped core  26  with cylindrical part  27 , transverse part  28  and a central channel  29 . On the T-shaped core  26 , a sleeve  30  is slidably mounted. The sleeve  30  has an upper transverse wall  32  and a lower transverse wall  34 , both walls abutting the outer wall  35  of the cylindrical part  27 . A longitudinal wall  37  extends beyond the lower transverse wall  34  at a lower end  40  of the first connector part  20  such as to form a tapering cavity  39 , as can be seen in  FIG. 3   b . In the cavity  39 , the frusto-conical coupling head  43  of the second connector part  22  is received. Double block and bleed (insulation) valves  44 , 45  are attached to each duct section  21 , 23 . 
     A first sealing ring  46  is placed against an inner surface of the upper transverse wall part  32  of the sleeve  30  and sealingly contacts the outer wall  35  of the cylindrical part  27  of the T-shaped core  26  and can slide together with the sleeve  30  up and down along the cylindrical part. A second seal  47  is placed in a groove in the lower transverse wall part  34  of the sleeve  30  such as to sealingly contact the coupling head  22 . 
     In the coupled state as shown in  FIG. 3   a , the sleeve  30  is pushed downward by the hydraulic cylinders  25  such that the first seal  46  is pressed by the upper transverse wall part  32  against the transverse part  28  in a sealing manner. Upper locking pins  50  extend through openings in the longitudinal wall  37  into openings  52  in the transverse part  28 . Lower locking pins  51  extend through openings in the lower end part of the longitudinal wall  37  of the sleeve  30  into a groove  53  in the connector part  22 . The locking pins  50 , 51  may be actuated in a hydraulic or pneumatic manner. 
     Upon disconnecting the riser-supporting buoy  11  from the cavity  1 , hydrocarbon production via the risers  12  is stopped. The insulation valves  44 ,  45  on both sides of the connector parts are closed and the duct section between valves  44 , 45  is depressurized and flushed with N2. The upper and lower locking pins  50 ,  51  are released and the sleeve  30  is retracted as shown in  FIG. 3   b.    
     For connecting the riser-supporting buoy to the cavity, the buoy is hauled into place via a winch and the connector  6  is operated to lock the buoy in position. Next, the riser ends are aligned with the piping  17  on the vessel while the sleeve  30  is retracted, such as shown in  FIG. 3   b . Thereafter the sleeve  30  is lowered by actuation of the hydraulic cylinders  25  and the upper and lower locking pins  50 ,  51  are engaged simultaneously. Then the sealing function of both seals  46 , 47  is tested, the valves  44 , 45  are opened and hydrocarbon production is started.