Vertical stab tendon bottom connector and method for securing and releasing the same

Abstract

A bottom connector for the tendon of a tension leg platform uses a latch ring with an outer profile to engage a mating profile in a receptacle on the sea floor. The latch ring moves radially within a housing, relative to the receptacle, between an engaged position and a retracted position. The latch ring engages the receptacle by lowering the connector into the receptacle below the mating profile and then lifting it until the latch ring locks into the receptacle. The latch ring disengages the receptacle by lowering the connector beyond a recess located below the mating profile and then lifting the connector out of the receptacle. As the connector is lifted above the recess, a retaining ring is actuated by the recess to retain the latch ring in its retracted position.

We claim:  
     
       1. A bottom connector for a tension leg platform tendon, comprising: 
       a receptacle adapted to be mounted on the sea floor, the receptacle having a bore with an inner profile and a recess located below the inner profile;  
       a body adapted to be secured to the lower end of the tendon and lowered into the receptacle;  
       an outwardly-biased latch carried by the body and having an outer profile which engages the inner profile of the receptacle in an engaged position to limit upward movement of the body, and a retracted position wherein the latch is retracted out of engagement with the inner profile;  
       a retainer slidably mounted to the body and having a released position relative to the latch which allows the latch to move to the engaged position, and a locked position which holds the latch in the retracted position; and  
       wherein lowering the body until the retainer engages the recess and then lifting the body causes the retainer to assume the locked position, thereby allowing the body to be withdrawn from the receptacle with the latch being held in the retracted position.  
     
     
       2. The bottom connector of  claim 1  wherein the body is axially movable relative to the retainer, the retainer having an upper portion which engages the latch while the retainer is in the locked position. 
     
     
       3. The bottom connector of  claim 2 , further comprising an internal groove in the retainer; and wherein 
       the latch has a rib which engages the internal groove in the retainer when the retainer is in the released position, and is disengaged from the groove in the retainer when the retainer is in the locked position.  
     
     
       4. The bottom connector of  claim 1  wherein the latch is a split ring. 
     
     
       5. A bottom connector for a tension leg platform tendon, comprising: 
       a receptacle adapted to be mounted on the sea floor, the receptacle having a bore with an inner profile and a recess located below the inner profile;  
       a body adapted to be secured to the lower end of the tendon and lowered into the receptacle;  
       an outwardly-biased latch carried by the body and having an outer profile which engages the inner profile of the receptacle in an engaged position to limit upward movement of the body, and a retracted position wherein the latch is retracted out of engagement with the inner profile;  
       a retainer mounted to the body and having a released position relative to the latch which allows the latch to move to the engaged position, and a locked position which holds the latch in the retracted position; and  
       wherein lowering the body until the retainer engages the recess and then lifting the body causes the retainer to assume the locked position, thereby allowing the body to be withdrawn from the receptacle with the latch being held in the retracted position; and  
       wherein the latch is axially movable relative to the retainer while the retainer engages the recess, causing the retainer to assume the locked position.  
     
     
       6. The bottom connector of  claim 5  wherein the latch and the body move upward relative to the retainer while the retainer engages the recess to move from the released position to the locked position. 
     
     
       7. The bottom connector of  claim 5  wherein the retainer has a portion located radially outward of and engaging an outer surface of the latch while the retainer is in the locked position. 
     
     
       8. The bottom connector of  claim 5 , further comprising a spring mounted to the body for biasing the latch outward; and wherein 
       the latch comprises a plurality of segments, each of which is outwardly pivotal about a pivot point on a lower end.  
     
     
       9. The bottom connector of  claim 5 , further comprising a split ring mounted to the body for biasing the latch outward; and wherein 
       the latch comprises a plurality of segments, each of which is outwardly pivotal about a pivot point on a lower end.  
     
     
       10. A bottom connector for a tension leg platform tendon, comprising: 
       a receptacle adapted to be mounted on the sea floor, the receptacle having a bore with an inner profile and a recess located below the inner profile;  
       a body adapted to be secured to the lower end of the tendon and lowered into the receptacle;  
       an outwardly-biased latch carried by the body and having an outer profile which engages the inner profile of the receptacle in an engaged position to limit upward movement of the body, and a retracted position wherein the latch is retracted out of engagement with the inner profile;  
       a retainer mounted to the body and having a released position relative to the latch which allows the latch to move to the engaged position, and a locked position which holds the latch in the retracted position; and  
       wherein lowering the body until the retainer engages the recess and then lifting the body causes the retainer to assume the locked position, thereby allowing the body to be withdrawn from the receptacle with the latch being held in the retracted position; and wherein the body comprises:  
       an inner body portion which is adapted to be secured to the lower end of the tendon;  
       an annular outer body portion surrounding the inner body portion; and  
       a flexible element located between the inner body portion and the outer body portion for accommodating a limited amount of pivotal movement between the inner and the outer bodies.  
     
     
       11. A bottom connector for a tension leg platform tendon, comprising: 
       a receptacle adapted to be mounted on the sea floor, the receptacle having a bore with an inner profile and a recess located below the inner profile;  
       a body adapted to be secured to the lower end of the tendon and lowered into the receptacle;  
       an outwardly-biased latch carried by the body and having an outer profile which engages the inner profile of the receptacle in an engaged position to limit upward movement of the body, and a retracted position wherein the latch is retracted out of engagement with the inner profile;  
       a retainer mounted to the body and having a released position relative to the latch which allows the latch to move to the engaged position, and a locked position which holds the latch in the retracted position; and  
       wherein lowering the body until the retainer engages the recess and then lifting the body causes the retainer to assume the locked position, thereby allowing the body to be withdrawn from the receptacle with the latch being held in the retracted position; and  
       wherein the retainer is mounted to the body for limited axial movement relative to the body; and wherein  
       the recess has a downward-facing shoulder which contacts the retainer as the body is lifted, moving the body upward relative to the retainer.  
     
     
       12. A bottom connector for a tension leg platform tendon, comprising: 
       a receptacle adapted to be mounted on the sea floor, the receptacle having a bore with an inner profile and a recess located below the inner profile;  
       a body adapted to be secured to the lower end of the tendon and lowered into the receptacle;  
       an outwardly-biased latch carried by the body and having an outer profile which engages the inner profile of the receptacle in an engaged position to limit upward movement of the body, and a retracted position wherein the latch is retracted out of engagement with the inner profile;  
       a retainer mounted to the body and having a released position relative to the latch which allows the latch to move to the engaged position, and a locked position which holds the latch in the retracted position; and  
       wherein lowering the body until the retainer engages the recess and then lifting the body causes the retainer to assume the locked position, thereby allowing the body to be withdrawn from the receptacle with the latch being held in the retracted position;  
       an intermediate groove in the receptacle between the inner profile and the recess; and  
       a lock member on a lower part of the retainer, the lock member engaging the intermediate groove in the receptacle when the latch engages the inner profile to releasably prevent downward movement of the body in the receptacle.  
     
     
       13. A bottom connector for a tension leg platform tendon, comprising: 
       a receptacle adapted to be mounted on the sea floor, the receptacle having a bore with an inner profile and a recess located below the inner profile;  
       a body adapted to be secured to the lower end of the tendon and lowered into the receptacle;  
       an outwardly-biased latch carried by the body and having an outer profile which engages the inner profile of the receptacle in an engaged position to limit upward movement of the body, and a retracted position wherein the latch is retracted out of engagement with the inner profile;  
       a retainer mounted to the body and having a released position relative to the latch which allows the latch to move to the engaged position, and a locked position which holds the latch in the retracted position; and  
       wherein lowering the body until the retainer engages the recess and then lifting the body causes the retainer to assume the locked position, thereby allowing the body to be withdrawn from the receptacle with the latch being held in the retracted position; and  
       wherein the body has a downward-inclined shoulder and the latch is slidably movable along the inclined shoulder.  
     
     
       14. The bottom connector of  claim 13 , further comprising a lock member mounted to the body for limited axial movement relative to the body, the lock member having an upper side that is flush with the inclined shoulder while in an upper position, the upper side of the lock member being in engagement with a lower side of the latch, wherein an upward poll on the tendon while the latch is in engagement with the inner profile causes the body to move slightly upward relative to the lock member and the latch to hold the latch outward in the engaged position. 
     
     
       15. A bottom connector for a tension leg platform tendon, comprising: 
       a receptacle adapted to be mounted on the sea floor, the receptacle having a bore with an inner profile and a recess located below the inner profile;  
       a body adapted to be secured to the lower end of the tendon and lowered into the receptacle;  
       an outwardly-biased latch carried by the body and having an outer profile which engages the inner profile of the receptacle in an engaged position to limit upward movement of the body, and a retracted position wherein the latch is retracted out of engagement with the inner profile;  
       a retainer mounted to the body and having a released position relative to the latch which allows the latch to move to the engaged position, and a locked position which holds the latch in the retracted position; and  
       wherein lowering the body until the retainer engages the recess and then lifting the body causes the retainer to assume the locked position, thereby allowing the body to be withdrawn from the receptacle with the latch being held in the retracted position; and  
       wherein the retainer is a split ring located above the latch, the split ring having a lower portion which extends downward over the latch when in the locked position.  
     
     
       16. The bottom connector of  claim 15  wherein the retainer is a split ring located above the latch, the split ring having a lower portion which extends downward over the latch when in the locked position, and a rib which extends into a slot in the body for holding the split ring in the locked position, the rib being spaced above the slot and the lower portion being spaced above the latch in the released position. 
     
     
       17. A bottom connector for a tension leg platform tendon, comprising: 
       a receptacle adapted to be mounted on the sea floor, the receptacle having a bore with an inner profile and a recess located below the inner profile;  
       a body adapted to be secured to the lower end of the tendon and lowered into the receptacle;  
       an outwardly-biased latch carried by the body and having an outer profile which engages the inner profile of the receptacle in an engaged position to limit upward movement of the body, and a retracted position wherein the latch is retracted out of engagement with the inner profile;  
       a retainer sleeve mounted to the body which is axially movable relative to the sleeve, the sleeve having a released position relative to the latch which allows the latch to move to the engaged position, and a locked position which holds the latch in the retracted position, the latch moving upward relative to the sleeve as the sleeve moves from the released position to the locked position; and  
       wherein lowering the body until the sleeve engages the recess and then lifting the body causes the sleeve to assume the locked position.  
     
     
       18. The bottom connector of  claim 17  wherein the sleeve has a portion located outward of and engaging an outer surface of the latch while the sleeve is in the locked position. 
     
     
       19. The bottom connector of  claim 17 , further comprising a spring for biasing the latch outward; and wherein 
       the latch comprises a plurality of segments, each of which is outwardly pivotal about a pivot point on a lower end.  
     
     
       20. The bottom connector of  claim 17 , further comprising an internal groove in the sleeve; and wherein 
       the latch has a rib which engages the internal groove in the sleeve when the sleeve is in the released position, and is disengaged from the groove in the sleeve when the sleeve is in the locked position.  
     
     
       21. The bottom connector of  claim 17  wherein the sleeve has a lock member portion mounted to the body for limited axial movement relative to the body; and wherein 
       the recess has a downward-facing shoulder which is contacted by the lock member portion of the sleeve to cause the body to move upward relative to the sleeve while the body is lifted.  
     
     
       22. The bottom connector of  claim 17 , further comprising: 
       an intermediate groove in the receptacle between the inner profile and the recess; and  
       a lock member on a lower part of the sleeve, the lock member engaging the intermediate groove in the receptacle when the latch engages the inner profile to releasably prevent downward movement of the body in the receptacle.  
     
     
       23. The bottom connector of  claim 17  wherein the body has a downward-inclined shoulder and the latch is a split ring which is slidably movable along the inclined shoulder. 
     
     
       24. The bottom connector of  claim 17 , further comprising a split ring lock member mounted to the body in engagement with the sleeve for releasably holding the sleeve to the body for axial movement therewith, the lock member being engagable with the recess, the body being movable axially relative to the lock member, wherein an upward pull on the tendon while the lock member is engaging the recess causes the latch and the body move upward relative to the sleeve to cause the sleeve to hold the latch in the retracted position. 
     
     
       25. The bottom connector of  claim 17  wherein the sleeve comprises a split ring located above the latch, the split ring having a lower portion which extends downward over the latch when in the locked position, and a rib which extends into a slot in the body for holding the split ring in the locked position, the rib being spaced above the slot and the lower portion being spaced above the latch in the releasably position. 
     
     
       26. A bottom connector for a tension leg platform tendon, comprising: 
       a receptacle adapted to be mounted on the sea floor, the receptacle having a bore with an inner profile and a recess located below the inner profile;  
       a body adapted to be secured to the lower end of the tendon and lowered with the tendon into the receptacle;  
       a plurality of latch segments, each of which is outwardly pivotal about a pivot point on a lower end, the latch segments being carried by the body and having an outer profile which engages the inner profile of the receptacle in an outward engaged position to limit upward movement of the body, and an inward retracted position wherein the latch segments are retracted out of engagement with the inner profile;  
       a split ring mounted to the body for biasing the latch segments in an outward direction;  
       an axially movable retainer sleeve mounted to the body and having a released position relative to the latch segments which allows the latch segments to move outward to the engaged position, and a locked position wherein an upper portion holds the latch segments in the retracted position; and wherein  
       lowering the body until the sleeve engages the recess and then lifting upward causes the latch segments to move upward relative to the sleeve, placing the sleeve in the locked position.  
     
     
       27. The bottom connector of  claim 26 , further comprising: 
       an internal groove in the sleeve; and wherein  
       each of the latch segments has a rib which engages the internal groove in the sleeve when the sleeve is in the released position, and is disengaged from the internal groove in the sleeve when the sleeve is in the locked position.  
     
     
       28. The bottom connector of  claim 26  wherein the sleeve has a lock member portion mounted to the body for limited axial movement relative to the body; and wherein 
       the recess has a downward-facing shoulder which contacts the lock member portion of the sleeve as the body is lifted for moving the body upward relative to the lock member and the sleeve.  
     
     
       29. The bottom connector of  claim 26 , further comprising an intermediate groove in the receptacle between the inner profile and the recess; and 
       a split ring lock member on a lower part of the sleeve, the lock member engaging the intermediate groove in the receptacle when the latch segments engage the inner profile to releasably prevent downward movement of the body in the receptacle.  
     
     
       30. A bottom connector for a tension leg platform tendon, comprising: 
       a receptacle adapted to be mounted on the sea floor, the receptacle having a bore with an inner profile and a recess located below the inner profile;  
       a body adapted to be secured to the lower end of the tendon and having a slot and a downward-inclined shoulder;  
       an outwardly-biased, split ring latch carried by the body on the shoulder and having an outer profile which engages the inner profile of the receptacle in an engaged position to limit upward movement of the body, and a retracted position wherein the latch is retracted out of engagement with the inner profile;  
       a split ring retainer mounted to the body above the latch for axial movement relative to the body and the latch, the retainer having a released position relative to the latch which allows the latch to move to the engaged position, and a locked position wherein a lower portion of the split ring extends downward over the latch to hold the latch in the retracted position;  
       a rib on an inner portion of the retainer which extends into the slot in the body for holding the split ring in the locked position, the rib being in disengagement with the slot and above the slot while the retainer is in the released position; and wherein  
       lowering the body until the retainer engages the recess and then lifting the body upward causes the retainer to assume the locked position.  
     
     
       31. The bottom connector of  claim 30 , further comprising a lock member mounted to the body for limited axial movement relative to the body, the lock member having an upper side flush with the inclined shoulder while in an upper position, the upper side of the lock member being in engagement with a lower side of the latch, wherein an upward pull on the tendon while the latch is in engagement with the inner profile causes the body to move slightly upward relative to the lock member and the latch to hold the latch in the engaged position. 
     
     
       32. A method for securing and releasing a bottom connector on a tension leg platform tendon, comprising: 
       (a) providing a receptacle on the sea floor with a bore having an inner profile and a recess located below the inner profile;  
       (b) securing a body to a lower end of the tendon, the body having a retainer mounted thereto and an outwardly-biased latch with an outer profile for engaging the inner profile of the receptacle, the retainer being in a released position relative to the latch which allows the latch to move to an engaged position;  
       (c) lowering the body into the receptacle and engaging the latch with the inner profile of the receptacle to limit upward movement of the body; and then to disengage the bottom connector,  
       (d) lowering the body until the retainer is located in the recess in the receptacle; and then  
       (e) lifting the body out of the receptacle, causing the retainer to move to a locked position which holds the latch in a retracted position out of engagement with the inner profile.  
     
     
       33. The method of  claim 32  wherein step (c) comprises lowering the latch below the inner profile, then raising the body and the latch until the latch engages the inner profile. 
     
     
       34. The method of  claim 32  wherein step (e) comprises moving a portion of the retainer into engagement with an outer surface of the latch while the retainer is in the locked position. 
     
     
       35. A method for securing and releasing a bottom connector on a tension leg platform tendon, comprising: 
       (a) providing a receptacle on the sea floor with a bore having an inner profile and a recess located below the inner profile;  
       (b) securing a body to a lower end of the tendon, the body having a retainer and an outwardly-biased latch with an outer profile for engaging the inner profile of the receptacle, the retainer being in a released position relative to the latch which allows the latch to move to an engaged position;  
       (c) lowering the body into the receptacle and engaging the latch with the inner profile of the receptacle to limit upward movement of the body; and then to disengage the bottom connector.  
       (d) lowering the body until the retainer is located in the recess in the receptacle; and then  
       (e) lifting the body out of the receptacle, causing the retainer to move to a locked position which holds the latch in a retracted position out of engagement with the inner profile; and wherein step (e) comprises  
       moving the body and the latch upward relative to the retainer while the retainer is in the recess.  
     
     
       36. The method of  claim 35 , further comprising: 
       retaining the body against downward movement up to a selected downward force after step (c) and before step (d); and wherein step (d) comprises  
       applying a downward force on the body which is greater than said selected downward force.  
     
     
       37. A connector comprising: 
       
         a receptacle having a bore with an inner profile and a recess located below the inner profile;  
       
       
         a body adapted to be lowered into the receptacle;  
       
         an outwardly - biased latch carried by the body and having an outer profile which engages the inner profile of the receptacle in an engaged position to limit upward movement of the body, and a retracted position wherein the latch is retracted out of engagement with the inner profile;    
       
         a retainer slidably mounted to the body and having a released position relative to the latch which allows the latch to move to the engaged position, and a locked position which holds the latch in the retracted position; and  
       
       
         wherein lowering the body until the retainer engages the recess and then lifting the body causes the retainer to assume the locked position, thereby allowing the body to be withdrawn from the receptacle with the latch being held in the retracted position. 
       
     
     
       38. The connector of  claim 37  wherein the body is axially movable relative to the retainer, the retainer having an upper portion which engages the latch while the retainer is in the locked position. 
     
     
       39. The connector of  claim 37 , further comprising an internal groove in the retainer; and wherein 
       
         the latch has a rib which engages the internal groove in the retainer when the retainer is in the released position, and is disengaged from the groove in the retainer when the retainer is in the locked position. 
       
     
     
       40. The connector of  claim 37  wherein the latch is a split ring. 
     
     
       41. A connector comprising: 
       
         a receptacle having a bore with an inner profile and a recess located below the inner profile;  
       
       
         a body adapted to be lowered into the receptacle;  
       
         an outwardly - biased latch carried by the body and having an outer profile which engages the inner profile of the receptacle in an engaged position to limit upward movement of the body, and a retracted position wherein the latch is retracted out of engagement with the inner profile;    
       
         a retainer sleeve mounted to the body which is axially movable relative to the sleeve, the sleeve having a released position relative to the latch which allows the latch to move to the engaged position, and a locked position which holds the latch in the retracted position, the latch moving upward relative to the sleeve as the sleeve moves from the released position to the locked position; and  
       
       
         wherein lowering the body until the sleeve engages the recess and then lifting the body causes the sleeve to assume the locked position. 
       
     
     
       42. The connector of  claim 41  wherein the sleeve has a portion located outward of and engaging an outer surface of the latch while the sleeve is in the locked position. 
     
     
       43. The connector of  claim 41 , further comprising a spring for biasing the latch outward; and wherein 
       
         the latch comprises a plurality of segments, each of which is outwardly pivotal about a pivot point on a lower end. 
       
     
     
       44. The connector of  claim 41 , further comprising: 
       
         an internal groove in the sleeve; and wherein  
       
       
         the latch has a rib which engages the internal groove in the sleeve when the sleeve is in the released position, and is disengaged from the groove in the sleeve when the sleeve is in the locked position. 
       
     
     
       45. The connector of  claim 41 , wherein the sleeve has a lock member portion mounted to the body for limited axial movement relative to the body; and wherein 
         the recess has a downward - facing shoulder which is contacted by the lock member portion of the sleeve to cause the body to move upward relative to the sleeve while the body is lifted.   
     
     
       46. The connector of  claim 41 , further comprising: 
       
         an intermediate groove in the receptacle between the inner profile and the recess; and  
       
       
         a lock member on a lower part of the sleeve, the lock member engaging the intermediate groove in the receptacle when the latch engages the inner profile to releasably prevent downward movement of the body in the receptacle. 
       
     
     
       47. The connector of  claim 41  wherein the body has a downward- inclined shoulder and the latch is a split ring which is slidably movable along the inclined shoulder.   
     
     
       48. The connector of  claim 41 , further comprising a split ring lock member mounted to the body in engagement with the sleeve for releasably holding the sleeve to the body for axial movement therewith, the lock member being engagable with the recess, the body being movable axially relative to the lock member, wherein an upward pull on the body while the lock member is engaging the recess causes the latch and the body move upward relative to the sleeve to cause the sleeve to hold the latch in the retracted position. 
     
     
       49. The connector of  claim 41  wherein the sleeve comprises a split ring located above the latch, the split ring having a lower portion which extends downward over the latch when in the locked position, and a rib which extends into a slot in the body for holding the split ring in the locked position, the rib being spaced above the slot and the lower portion being spaced above the latch in the released position. 
     
     
       50. A method for securing and releasing a connector comprising: 
       ( a )  providing a receptacle on the sea floor with a bore having an inner profile and a recess located below the inner profile;    
       ( b )  providing a body having a retainer mounted thereto and an outwardly - biased latch with an outer profile for engaging the inner profile of the receptacle, the retainer being in a released position relative to the latch which allows the latch to move to an engaged position;    
       ( c )  lowering the body into the receptacle and engaging the latch with the inner profile of the receptacle to limit upward movement of the body, and then to disengage the connector;    
       ( d )  lowering the body until the retainer is located in the recess in the receptacle; and then    
       ( e )  lifting the body out of the receptacle, causing the retainer to move to a locked position which holds the latch in a retracted position out of engagement with the inner profile.   
     
     
       51. The method of  claim 50  wherein step ( c )  comprises lowering the latch below the inner profile, then raising the body and the latch until the latch engages the inner profile.   
     
     
       52. The method of  claim 50  wherein step ( e )  comprises moving a portion of the retainer into engagement with an outer surface of the latch while the retainer is in the locked position.