Threaded connector having metal-to-metal seal

Abstract

Threaded connectors for tubular members having metal-to-metal seals are provided. The connectors have different shapes for the contact sealing surfaces of the first and second connectors, which may be male and female connectors. In particular, the contact sealing surfaces may have mismatched surface shapes. For example, the male connector may have a frustohemispherical scaling surface while the female connector may have a frustoconical sealing surface. The disclosed mismatched male and female curvilinear surfaces, along with the flexible male connector nose, facilitate a reliable threaded connection having a metal-to-metal seal. The mismatched surfaces may provide for a wide parabolic distribution of contact stresses along the metal-to-metal seal of the curvilinear sealing surfaces.

What is claimed is: 
     
         1 . A connector assembly comprising:
 a first connector member having an exterior curvilinear sealing surface;   a second connector member having an interior curvilinear sealing surface;   wherein the first connector member is adapted to be received by the second connector member, allowing a connection to be formed; and   wherein the exterior curvilinear sealing surface and the interior curvilinear sealing surface have portions with non-complementary surface shapes.   
     
     
         2 . The connector assembly of  claim 1  wherein:
 the interior and exterior curvilinear surfaces are selected from a group consisting of frustoconical surfaces, frustocylindrical surfaces, frustoellipsoidal surfaces, frustospheroidal surfaces, frustohemispherical surfaces, frustoparabolic surfaces, frustohyperbolic surfaces, frutstoroidal surfaces, and blends thereof; and 
 wherein one of the curvilinear sealing surfaces is selected from the group and the other of the curvilinear surfaces is selected from the remaining members of the group. 
 
     
     
         3 . The connector assembly of  claim 1  wherein:
 the first connector member further comprises tapered external threads disposed on a section of the first connector member adjacent to the exterior curvilinear sealing surface; and 
 the second connector member further comprises tapered internal threads disposed on a section of the second connector member adjacent to the interior curvilinear sealing surface, wherein the tapered external threads are complementary to the tapered internal threads. 
 
     
     
         4 . The connector assembly of  claim 3  wherein:
 the interior curvilinear sealing surface or the second connector member contains a recess adjacent to a nose of the first connector member when the first connector member is seated in the second connector member. 
 
     
     
         5 . The connector assembly of  claim 3  wherein:
 the first connector member has a flexible nose that will allow the first connector member to rotate into a different orientation while seated inside of the second connector member. 
 
     
     
         6 . The connector assembly of  claim 5  wherein:
 the different orientation creates a new contact area between the interior curvilinear sealing surface and exterior curvilinear sealing surface; and 
 surface contact stresses are exerted by a metal-to-metal seal in the contact area. 
 
     
     
         7 . The connector assembly of  claim 6  wherein:
 the different orientation causes a rapid pressure-energization of the metal-to-metal seal when the connection is under either internal or external pressure; and 
 wherein during the pressure-energization, the new contact area widens and the surface contact stresses increase in magnitude. 
 
     
     
         8 . The connector assembly of  claim 1  wherein:
 the first connector member comprises a pin; and 
 the second connector member comprises a box. 
 
     
     
         9 . The connector assembly of  claim 1  wherein:
 the first connector member is a pin connector comprising a pin nose and an annular groove on the exterior surface of the pin connector proximate the pin nose; and 
 the second connector is a box connector. 
 
     
     
         10 . The connector assembly of  claim 1  wherein:
 a gap in a direction parallel to an axis or the first and second connector members is present between an end of the first connector member and a shoulder of the second connector member. 
 
     
     
         11 . A method comprising:
 receiving a first connector member into a second connector member;   wherein the first connector member has on exterior curvilinear sealing surface and the second connector member has an interior curvilinear sealing surface; and   wherein the exterior curvilinear sealing surface and the interior curvilinear sealing surface have portions with non-complementary surface shapes.   
     
     
         12 . The method of  claim 11  wherein:
 the interior and exterior curvilinear surfaces are selected from a group consisting of frustoconical surfaces, frustocylindrical surfaces, frustoellipsoidal surfaces, frustospheroidal surfaces, frustohemispherical surfaces, frustoparabolic surfaces, frustohyperbolic surfaces, frutstoroidal surfaces, and blends thereof; and 
 wherein one of the curvilinear sealing surfaces is selected from the group and the other of the curvilinear surfaces is selected from the remaining members of the group. 
 
     
     
         13 . The method of  claim 11  wherein:
 the first connector member further comprises tapered external threads disposed on a section of the first connector member adjacent to the exterior curvilinear sealing surface; and 
 the second connector member further comprises tapered internal threads disposed on a section of the second connector member adjacent to the interior curvilinear sealing surface, wherein the tapered external threads are complementary to the tapered internal threads. 
 
     
     
         14 . The method of  claim 13  wherein:
 the interior curvilinear sealing surface of the second connector member contains a recess adjacent to a nose of the first connector member when the first connector member is seated in the second connector member. 
 
     
     
         15 . The method of  claim 13  further comprising:
 allowing the first connector member to rotate into a different orientation while seated inside the second connector member via a flexible nose of the first connector member. 
 
     
     
         16 . The method of  claim 15  further comprising:
 creating a new contact area between the interior curvilinear sealing surface and exterior curvilinear surface via the first connector member rotating into the different orientation; and 
 exerting surface contact stresses via a metal-to-metal seal in the new contact area. 
 
     
     
         17 . The method of  claim 16  further comprising:
 causing a rapid pressure-energization of the metal-to-metal seal when the connection is under either internal or external pressure; and 
 during the pressure-energization, widening the new contact area and increasing a magnitude of the surface contact stresses. 
 
     
     
         18 . The method of  claim 11  wherein:
 the first connector member comprises a pin; and 
 the second connector member comprises a box. 
 
     
     
         19 . The method of  claim 11  wherein:
 the first connector member is a pin connector comprising a pin nose and an annular groove on the exterior surface of the pin connector proximate the pin nose; and 
 the second connector is a box connector. 
 
     
     
         20 . The method of  claim 11  wherein:
 a gap in a direction parallel to an axis of the first and second connector members is present between an end of the first connector member and a shoulder of the second connector member