Pipe Element Having Wedging Groove

Abstract

A pipe element has a circumferential groove with a surface portion oriented at an angle with respect to its longitudinal axis. A surface portion of the groove adjacent to the angled surface portion is oriented perpendicular to the longitudinal axis. A mechanical coupling has projecting keys that engage the groove. The keys have mating surfaces that contact both the perpendicular and angled surface portions of the groove. When the pipe element and coupling are used in combination to form a pipe joint, axial load on the pipe, resisted by the mechanical coupling, is shared between the perpendicular and angled surface portions which results in a pipe joint that can withstand higher internal pressure than if the axial load were borne by the perpendicular surface portion alone.

What is claimed is: 
     
         1 . A method of using a coupling having an arcuate projection engaged with a groove positioned in an outer surface proximate to a first end of a pipe element extending along a longitudinal axis, said groove comprising:
 a first sub-surface oriented at an angle with respect to said longitudinal axis and facing away from said first end;   a second sub-surface oriented at an angle with respect to said longitudinal axis, said second sub-surface being in spaced relation away from and facing toward said first sub-surface;   a third sub-surface contiguous with said first sub-surface, said third sub-surface oriented at a non-zero angle with respect to said longitudinal axis and sloping toward said second sub-surface; and   a fourth sub-surface contiguous with said third and second sub surfaces, said fourth sub-surface being oriented at an angle with respect to said longitudinal axis;   said method comprising:
 contacting said third sub-surface with a first portion of said arcuate projection of said coupling while maintaining a gap between said first sub-surface and a second portion of said arcuate projection of said coupling; and 
 applying a tensile force between said pipe element and said coupling, thereby causing said gap to close and said second portion of said arcuate projection of said coupling to engage said first sub-surface. 
   
     
     
         2 . The method according to  claim 1 , wherein said tensile force causes wedging between said third sub-surface and said first portion of said arcuate projection of said coupling. 
     
     
         3 . The method according to  claim 1  further comprising:
 contacting said second sub-surface with a third portion of said arcuate projection of said coupling while maintaining said gap between said first sub-surface and said second portion of said arcuate projection of said coupling. 
 
     
     
         4 . The method according to  claim 3 , wherein said tensile force causes a second gap to form between said second sub-surface and said third portion of said arcuate projection of said coupling. 
     
     
         5 . The method according to  claim 1 , wherein said second sub-surface is oriented at an angle less than 90 degrees with respect to said longitudinal axis to bias said arcuate projection of said coupling towards said third sub-surface and said first sub-surface when said tensile force is applied. 
     
     
         6 . A method of using a coupling to connect a first pipe element having a first end and a second pipe element having a second end, said first and second pipe elements extending along a longitudinal axis, said first pipe element comprising:
 a first groove positioned proximate to said first end and configured to receive a first arcuate projection of said coupling, said first groove comprising:
 a first sub-surface oriented at an angle with respect to said longitudinal axis and facing away from said first end; 
 a second sub-surface oriented at an angle with respect to said longitudinal axis, said second sub-surface being in spaced relation away from and facing toward said first sub-surface; 
 a third sub-surface contiguous with said first sub-surface, said third sub-surface oriented at a non-zero angle with respect to said longitudinal axis and sloping toward said second sub-surface; and 
 a fourth sub-surface contiguous with said third and second sub surfaces, said fourth sub-surface being oriented at an angle with respect to said longitudinal axis; 
   said second pipe element comprising:
 a second groove positioned proximate to said second end and configured to receive a second arcuate projection of said coupling, said second groove comprising:
 a fifth sub-surface oriented at an angle with respect to said longitudinal axis and facing away from said second end; 
 a sixth sub-surface oriented at an angle with respect to said longitudinal axis, said sixth sub-surface being in spaced relation away from and facing toward said fifth sub-surface; 
 a seventh sub-surface contiguous with said fifth sub-surface, said seventh sub-surface oriented at a non-zero angle with respect to said longitudinal axis and sloping toward said sixth sub-surface; and 
 an eighth sub-surface contiguous with said seventh and sixth sub surfaces, said eighth sub-surface being oriented at an angle with respect to said longitudinal axis; 
 
   said method comprising:
 contacting said third sub-surface with a first portion of said first arcuate projection of said coupling while maintaining a first gap between said first sub-surface and a second portion of said first arcuate projection of said coupling; 
 contacting said seventh sub-surface with a first portion of said second arcuate projection of said coupling while maintaining a second gap between said fifth sub-surface and a second portion of said second arcuate projection of said coupling; and 
 applying a tensile force between said first and second pipe elements, thereby causing:
 said first gap to close, 
 said second portion of said first arcuate projection of said coupling to engage said first sub-surface, 
 said second gap to close, and 
 said second portion of said second arcuate projection of said coupling to engage said fifth sub-surface. 
 
   
     
     
         7 . The method according to  claim 6 , wherein said tensile force causes wedging between said third sub-surface and said first portion of said first arcuate projection of said coupling and said seventh sub-surface and said first portion of said second arcuate projection of said coupling. 
     
     
         8 . The method according to  claim 6  further comprising:
 contacting said second sub-surface with a third portion of said first arcuate projection of said coupling while maintaining said first gap between said first sub-surface and said second portion of said first arcuate projection of said coupling; and 
 contacting said sixth sub-surface with a third portion of said second arcuate projection of said coupling while maintaining said second gap between said fifth sub-surface and said second portion of said second arcuate projection of said coupling. 
 
     
     
         9 . The method according to  claim 8 , wherein said tensile force causes a third gap to form between said second sub-surface and said third portion of said first arcuate projection of said coupling, and a fourth gap to form between said sixth sub-surface and said third portion of said second arcuate projection of said coupling. 
     
     
         10 . The method according to  claim 6 , wherein said second sub-surface is oriented at an angle less than 90 degrees with respect to said longitudinal axis to bias said first arcuate projection of said coupling towards said third sub-surface and said first sub-surface when said tensile force is applied, wherein said sixth sub-surface is oriented at an angle less than 90 degrees with respect to said longitudinal axis to bias said second arcuate projection of said coupling towards said seventh sub-surface and said fifth sub-surface when said tensile force is applied. 
     
     
         11 . A method of forming a groove in an outer surface proximate to a first end of a pipe element extending along a longitudinal axis, said groove comprising:
 a first sub-surface oriented at an angle with respect to said longitudinal axis and facing away from said first end;   a second sub-surface oriented at an angle with respect to said longitudinal axis, said second sub-surface being in spaced relation away from and facing toward said first sub-surface;   a third sub-surface contiguous with said first sub-surface, said third sub-surface oriented at a non-zero angle with respect to said longitudinal axis and sloping toward said second sub-surface; and   a fourth sub-surface contiguous with said third and second sub surfaces, said fourth sub-surface being oriented at an angle with respect to said longitudinal axis;   said method comprising:
 using an inner roller contacting an inside surface of said pipe element and an outer roller contacting said outer surface of said pipe element to roll groove said groove in said pipe element. 
   
     
     
         12 . The method of  claim 11 , wherein said inner roller and said outer roller comprise corresponding profiles configured to form said groove. 
     
     
         13 . The method of  claim 11 , wherein said method further comprises rotating said inner roller about a first axis, thereby causing said pipe element to rotate which causes said outer roller to rotate about a second axis. 
     
     
         14 . The method of  claim 13 , wherein said pipe element and said outer roller each rotate as a result of contact friction between said inner roller and said pipe element and said pipe element and said outer roller. 
     
     
         15 . The method of  claim 11 , wherein said method further comprises forcing said outer roller toward said inner roller. 
     
     
         16 . The method of  claim 15 , wherein said outer roller is forced toward said inner roller via a hydraulic ram.