Threaded pipe connection with improved seal

Abstract

An improved coupling for joining together threaded tubular sections is disclosed. The coupling includes a seal seat between the threaded areas of the coupling and a seal assembly positioned on the seal seat. The seal assembly engages the end of the threaded tubular section and forms an axial seal without application of radial stress in the coupling. The seal assembly has an elastomeric component and a rigid component.

What is claimed is:  
     
         1 . A coupling for joining together threaded tubular sections, the coupling having opposing first and second internally threaded end sections, comprising: 
 (a) at least one seal seat positioned between the first internally threaded end section and the second internally threaded end section; and    (b) a removable seal assembly positioned on the seal seat, the seal assembly having an elastomeric component and a substantially rigid component, the elastomeric component being resilient and protruding axially from the substantially rigid component, the elastomeric component being axially compressible by at least one of the internally threaded end sections, the substantially rigid component limiting axial compression of the elastomeric component of the seal assembly and limiting the axial advancement of at least one of the internally threaded end sections.    
     
     
         2 . The coupling of  claim 1  further comprising a plurality of channels in the rigid component of the seal insert.  
     
     
         3 . The coupling of  claim 1  further comprising a snap surface adjacent the seal seat.  
     
     
         4 . The coupling of  claim 1  wherein the rigid component of the seal assembly has an outer perimeter and inner perimeter, and the seal seat has a diameter greater than the diameter of the outer perimeter of the rigid component.  
     
     
         5 . The coupling of  claim 4  wherein the coupling has a center section with an internal diameter smaller than the internal diameter of the first and second internally threaded end sections.  
     
     
         6 . The coupling of  claim 5  wherein the center section has opposing first and second shoulders and a seal seat adjacent each of the first and second shoulders.  
     
     
         7 . A coupling for joining together threaded tubular sections, each threaded tubular section having external threads, comprising: 
 (a) first and second internally threaded end sections, each end section having an internally tapered threaded area beginning at the outer end of the end section and terminating at a thread relief groove, the first and second end sections joined together to form an unthreaded intermediate area;    (b) a seal seat in the unthreaded intermediate area, the seal seat having an internal diameter less than the internal diameter of the threaded areas; and    (c) a seal assembly configured to fit on the seal seat, the seal assembly having a rigid component retaining at least one elastomeric seal element, the elastomeric seal element forming a seal with the end of a threaded tubular section by application of axial force against the seal element.    
     
     
         8 . The coupling of  claim 7  wherein the end of the threaded tubular section engages the elastomeric seal element before engaging the rigid component of the seal assembly.  
     
     
         9 . The coupling of  claim 7  wherein the rigid component limits axial compression of the elastomeric seal element.  
     
     
         10 . The coupling of  claim 7  wherein the threaded tubular section forms a metal-to-metal axial seal with the rigid component.  
     
     
         11 . The coupling of  claim 7  wherein the coupling includes a snap surface for retaining the seal assembly on the seal seat.  
     
     
         12 . The coupling of  claim 7  wherein the seal assembly includes at least one channel in the outer surface of the rigid component.  
     
     
         13 . An improved coupling for repeatedly joining together externally threaded tubular sections, comprising: 
 (a) first and second internally threaded ends and an unthreaded intermediate section axially spaced between the first and second internally threaded ends; and    (b) at least one seal assembly seated on a seal seat in the intermediate section and spaced axially between the first and second internally threaded ends, the seal assembly having an axially compressible resilient component and a substantially rigid component, the resilient component of the seal assembly forming a seal with the end of a threaded tubular section and the substantially rigid component limiting axial advancement of the externally threaded tubular section into the coupling.    
     
     
         14 . The improved coupling of  claim 13  wherein the rigid component comprises a metal retainer.  
     
     
         15 . The improved coupling of  claim 13  wherein the axially compressible resilient component protrudes axially from the rigid component.  
     
     
         16 . The improved coupling of  claim 13  further comprising a pair of axially compressible resilient components.  
     
     
         17 . The improved coupling of  claim 13  wherein the unthreaded intermediate section has internal shoulders and an inner diameter substantially the same as the inner diameter of the externally threaded tubular sections.  
     
     
         18 . The improved coupling of  claim 13  comprising a pair of seal assemblies, each seal assembly engaging the end of one of the externally threaded tubular sections.  
     
     
         19 . The improved coupling of  claim 13  further comprising a snap ridge for retaining the seal assembly in place on the seal seat.  
     
     
         20 . The improved coupling of  claim 13  wherein the coupling and threaded tubular sections have API threads.