Pipe joint

Abstract

A pipe joint has male and female couplers with interfitting features that join pipe sections together when the male coupler is positioned within the female coupler. The couplers can be separate rings or formed in the ends of lengths of pipe. Typically, a male coupler is at one end of a length of pipe and a female coupler is at the opposite end of the pipe. The interfitting features can include three or more ridges or teeth of a first coupler (a male coupler) and the same number of ridges or teeth of a second coupler (a female coupler) each tooth being positioned in a respective transition region of the coupler. Ramp surfaces of the couplers are positioned at opposite sides of each tooth. The ramp surfaces have respective slopes, and the interfitting features are designed to reduce the forces required to push the couplers together into a locked engagement.

I claim: 
     
       1. A pipe joint comprising:
 a first coupler with an inner wall surface and a first set of interfitting first coupler features on the inner wall surface, the first coupler comprising a first distal end defining a coupler receiving opening; 
 a second coupler with an outer wall surface and a second set of interfitting second coupler features on the outer wall surface, the second coupler comprising a second distal end, the first and second coupler features being sized and positioned to engage one another to join the first and second couplers together when the second coupler is inserted into the coupler receiving opening of the first coupler; 
 the first coupler features comprising a first coupler first tooth spaced from the first distal end and positioned in a first coupler first transition region, a first coupler second tooth positioned in a first coupler second transition region, and a first coupler intermediate tooth spaced from the first distal end and positioned in a first coupler intermediate transition region positioned between the first coupler first and second transition regions, the first coupler second transition region being positioned further from the first distal end than the first coupler first transition region; 
 the second coupler features comprising a second coupler first tooth spaced from the second distal end and positioned in a second coupler first transition region, a second coupler second tooth positioned in a second coupler second transition region, and a second coupler intermediate tooth spaced from the second distal end and positioned in a second coupler intermediate transition region positioned between the second coupler first and second transition regions, the second coupler second transition region being positioned further from the second distal end than the second coupler first transition region; 
 the first coupler features comprising a first coupler first ramp between the first coupler first tooth and the first distal end, a first coupler second ramp positioned further from the first distal end than the first coupler second tooth, and first coupler first and second intermediate ramps on opposite sides of first coupler intermediate tooth; 
 the second coupler features comprising a second coupler first ramp between the seconds second coupler first tooth and the second distal end, a second coupler second ramp positioned further from the second distal end than the second coupler second tooth, and second coupler first and second intermediate ramps on opposite sides of second coupler intermediate tooth; and 
 wherein the first coupler first ramp has a first coupler first ramp surface with a first coupler first ramp surface slope and the first coupler second ramp has a first coupler second ramp surface with a first coupler second ramp surface slope, and wherein the first coupler first ramp surface slope is greater than the first coupler second ramp surface slope. 
 
     
     
       2. An apparatus The pipe joint according to  claim 1  wherein the second coupler first ramp has a second coupler first ramp surface with a second coupler first ramp surface slope and the second coupler second ramp has a second coupler second ramp surface with a second coupler second ramp surface slope, and wherein the second coupler first ramp surface slope is less than the second coupler second ramp surface slope. 
     
     
       3. An apparatus The pipe joint according to  claim 2  wherein the second coupler second ramp surface slope is less than the first coupler first ramp surface slope. 
     
     
       4. An apparatus The pipe joint according to  claim 1  wherein the first coupler first intermediate ramp has a first coupler first intermediate ramp surface with a first coupler first intermediate ramp surface slope, the first coupler second intermediate ramp has a first coupler second intermediate ramp surface with a first coupler second intermediate ramp surface slope, the second coupler first intermediate ramp has a second coupler first intermediate ramp surface with a second coupler first intermediate ramp surface slope, and the second coupler second intermediate ramp has a second coupler second intermediate ramp surface with a second coupler second intermediate ramp surface slope; and wherein each of the ramp surface slopes is less than 0.1. 
     
     
       5. An apparatus The pipe joint according to  claim 4  wherein the first coupler first ramp surface slope and the first coupler intermediate ramp surface slopes are between 0.05 and 0.08, the first coupler second ramp surface slope is from 0.01 to 0.04; the second coupler first ramp surface slope is from 0.01 to 0.04 and the second coupler second ramp surface slope and the second coupler intermediate ramp surface slopes are from 0.05 to 0.08. 
     
     
       6. An apparatus The pipe joint according to  claim 4  wherein the second coupler first intermediate ramp surface slope and the second coupler second intermediate ramp surface slope are the same or approximately the same and are less than the second coupler second ramp surface slope; and wherein the second coupler second ramp surface slope, the second coupler first intermediate ramp surface slope and the second coupler second intermediate ramp surface slope are each greater than the than the second coupler first ramp surface slope. 
     
     
       7. An apparatus The pipe joint according to  claim 6  wherein the first coupler first intermediate ramp surface slope and the first coupler second intermediate ramp surface slope are the same or approximately the same, and wherein the first coupler first intermediate ramp surface slope and the first coupler second intermediate ramp surface slope are each greater than the first coupler first ramp surface slope and greater than the first coupler second ramp surface slope, and wherein the first coupler second ramp surface slope is less than the first coupler second first ramp surface slope. 
     
     
       8. An apparatus The pipe joint according to  claim 1  wherein each of the first and second couplers has a respective longitudinal axis, and wherein the tooth depth of each tooth is equal to the height of the tooth surface in the radial direction from the longitudinal axis and each tooth depth is within the range of from approximately 0.03 to 0.04 inches. 
     
     
       9. An apparatus The pipe joint according to  claim 1  wherein each of the first and second couplers has a respective longitudinal axis, and wherein the tooth depth of each tooth is equal to the height of the tooth surface in the radial direction from the longitudinal axis, and wherein the tooth depth is determined by the formula: Tooth or transition depth is equal to or approximately equal to: [[(pipe diameter/24)*0.005]+0.025], wherein * indicates multiplication and the pipe diameter is in inches. 
     
     
       10. An apparatus The pipe joint according to  claim 1  wherein the first coupler comprises a first longitudinal axis and wherein the first coupler features comprise a respective first coupler first annular surface of a constant diameter and coaxial with the first longitudinal axis positioned at the side of each tooth of the first coupler nearest to the first distal end and a respective first coupler second annular surface of a constant diameter and coaxial with the first longitudinal axis is positioned at the side of each tooth of the first coupler furthest from the first distal end; wherein the second coupler comprises a second longitudinal axis and wherein the second coupler features comprise a respective second coupler first annular surface of a constant diameter and coaxial with the second longitudinal axis positioned at the side of each tooth of the second coupler nearest to the second distal end and a respective second coupler second annular surface of a constant diameter and coaxial with the second longitudinal axis positioned at the side of each tooth of the second coupler furthest from the second distal end; wherein the widths of the first coupler first annular surfaces in the direction of the first longitudinal axis are less than the widths of the first coupler second annular surfaces in the direction of the first longitudinal axis; and wherein the widths of the second coupler first annular surfaces in the direction of the second longitudinal axis are less than the widths of the second coupler second annular surfaces in the direction of the second longitudinal axis. 
     
     
       11. An apparatus The pipe joint according to claim  1   10  wherein each of the first coupler first ramp, first coupler second ramp, first coupler first and second intermediate ramps, second coupler first ramp, second coupler second ramp, and second coupler first and second intermediate ramp ramps each have the same length in the longitudinal direction and wherein the first coupler first annular surfaces and second coupler first annular surfaces have a length in the longitudinal direction that is approximately five to ten percent of the length of the ramp sections ramps. 
     
     
       12. An apparatus The pipe joint according to  claim 1  wherein the first coupler features comprise a first shelf spaced further from the first distal end than the first coupler second transition region, the first coupler features also comprising a first coupler base section extending from the first shelf to the first coupler second ramp section and having a first coupler base section axial length, the first coupler also comprising a first coupler entrance section extending from the first distal end to the first coupler first ramp section and having a first coupler entrance section axial length, wherein the first coupler base section axial length that is longer than the first coupler entrance section axial length; and wherein the second coupler features comprise a second shelf spaced further from the second distal end than the second coupler second transition region, the second coupler features also comprising a second coupler base section extending from the second shelf to the second coupler second ramp section and having a second coupler base section axial length, the second coupler also comprising a second coupler entrance section extending from the second distal end to the second coupler first ramp section and having a second coupler entrance section axial length, wherein the second coupler base section axial length is longer than the second coupler entrance section axial length. 
     
     
       13. An apparatus The pipe joint according to  claim 12  wherein the first coupler base section axial length is the same as the second coupler base section axial length and the first coupler entrance section axial length is the same as the second coupler entrance section axial length. 
     
     
       14. An apparatus The pipe joint according to  claim 1  wherein the diameter of the second coupler at the location of the second coupler first tooth at the second coupler first transition region is less than or equal to the diameter of the first coupler first tooth at the location of the first coupler first transition region. 
     
     
       15. A pipe joint comprising:
 a first coupler with an inner wall surface and a first set of interfitting first coupler features on the inner wall surface, the first coupler comprising a first distal end defining a coupler receiving opening; 
 a second coupler with an outer wall surface and a second set of interfitting second coupler features on the outer wall surface, the second coupler comprising a second distal end, the first and second coupler features being sized and positioned to engage one another to join the first and second couplers together when the second coupler is inserted into the coupler receiving opening of the first coupler; 
 the first coupler features comprising a first coupler first tooth spaced from the first distal end and positioned in a first coupler first transition region, a first coupler second tooth positioned in a first coupler second transition region, and a first coupler intermediate tooth spaced from the first distal end and positioned in a first coupler intermediate transition region positioned between the first coupler first and second transition regions, the first coupler second transition region being positioned further from the first distal end than the first coupler first transition region; 
 the second coupler features comprising a second coupler first tooth spaced from the second distal end and positioned in a second coupler first transition region, a second coupler second tooth positioned in a second coupler second transition region, and a second coupler intermediate tooth spaced from the second distal end and positioned in a second coupler intermediate transition region positioned between the second coupler first and second transition regions, the second coupler second transition region being positioned further from the second distal end than the second coupler first transition region; 
 the first coupler features comprising a first coupler first ramp between the first coupler first tooth and the first distal end, a first coupler second ramp positioned further from the first distal end than the first coupler second tooth, and first coupler first and second intermediate ramps on opposite sides of first coupler intermediate tooth; 
 the second coupler features comprising a second coupler first ramp between the seconds second coupler first tooth and the second distal end, a second coupler second ramp positioned further from the second distal end than the second coupler second tooth, and second coupler first and second intermediate ramps on opposite sides of second coupler intermediate tooth; and 
 wherein the first coupler first ramp has a first coupler first ramp surface with a first coupler first ramp surface slope and the first coupler second ramp has a first coupler second ramp surface with a first coupler second ramp surface slope, and wherein the first coupler first ramp surface slope is greater than the first coupler second ramp surface slope; 
 wherein the second coupler first ramp has a second coupler first ramp surface with a second coupler first ramp surface slope and the second coupler second ramp has a second coupler second ramp surface with a second coupler second ramp surface slope, and wherein the second coupler first ramp surface slope is less than the second coupler second ramp surface slope; 
 wherein the second coupler second ramp surface slope is less than the first coupler first ramp surface slope; 
 wherein the first coupler first intermediate ramp has a first coupler first intermediate ramp surface with a first coupler first intermediate ramp surface slope, the first coupler second intermediate ramp has a first coupler second intermediate ramp surface with a first coupler second intermediate ramp surface slope, the second coupler first intermediate ramp has a second coupler first intermediate ramp surface with a second coupler first intermediate ramp surface slope, and the second coupler second intermediate ramp has a second coupler second intermediate ramp surface with a second coupler second intermediate ramp surface slope; and wherein each of the ramp surface slopes is less than 0.1; 
 wherein the second coupler first intermediate ramp surface slope and the second coupler second intermediate ramp surface slope are the same or approximately the same and are less than the second coupler second ramp surface slope; and wherein the second coupler second ramp surface slope, the second coupler first intermediate ramp surface slope and the second coupler second intermediate ramp surface slope are each greater than the than the second coupler first ramp surface slope; 
 wherein the first coupler first intermediate ramp surface slope and the first coupler second intermediate ramp surface slope are the same or approximately the same, and wherein the first coupler first intermediate ramp surface slope and the first coupler second intermediate ramp surface slope are each greater than the first coupler first ramp surface slope and greater than the first coupler second ramp surface slope, and wherein the first coupler second ramp surface slope is less than the first coupler second first ramp surface slope; 
 wherein each of the first and second couplers has a respective longitudinal axis, and wherein the tooth depth of each tooth is equal to the height of the tooth surface in the radial direction from the longitudinal axis and each tooth depth is within the range of from approximately 0.03 to 0.04 inches; 
 wherein the first coupler comprises a first longitudinal axis and wherein the first coupler features comprise a respective first coupler first annular surface of a constant diameter and coaxial with the first longitudinal axis positioned at the side of each tooth of the first coupler nearest to the first distal end and a respective first coupler second annular surface of a constant diameter and coaxial with the first longitudinal axis is positioned at the side of each tooth of the first coupler furthest from the distal end; wherein the second coupler comprises a second longitudinal axis and wherein the second coupler features comprise a respective second coupler first annular surface of a constant diameter and coaxial with the second longitudinal axis positioned at the side of each tooth of the second coupler nearest to the second distal end and a respective second coupler second annular surface of a constant diameter and coaxial with the second longitudinal axis positioned at the side of each tooth of the second coupler furthest from the second distal end; wherein the widths of the first coupler first annular surfaces in the direction of the first longitudinal axis are less than the widths of the first coupler second annular surfaces in the direction of the first longitudinal axis; and wherein the widths of the second coupler first annular surfaces in the direction of the second longitudinal axis are less than the widths of the second coupler second annular surfaces in the direction of the second longitudinal axis; 
 wherein the first coupler features comprise a first shelf spaced further from the first distal end than the first coupler second transition region, the first coupler features also comprising a first coupler base section extending from the first shelf to the first coupler second ramp section and having a first coupler base section axial length, the first coupler also comprising a first coupler entrance section extending from the first distal end to the first coupler first ramp section and having a first coupler entrance section axial length, wherein the first coupler base section axial length that is longer than the first coupler entrance section axial length; and wherein the second coupler features comprise a second shelf spaced further from the second distal end than the second coupler second transition region, the second coupler features also comprising a second coupler base section extending from the second shelf to the second coupler second ramp section and having a second coupler base section axial length, the second coupler also comprising a second coupler entrance section extending from the second distal end to the second coupler first ramp section and having a second coupler entrance section axial length, wherein the second coupler base section axial length is longer than the second coupler entrance section axial length; and 
 wherein the diameter of the second coupler at the location of the second coupler first tooth at the second coupler first transition region is less than or equal to the diameter of the first coupler first tooth at the location of the first coupler first transition region. 
 
     
     
       16. A pipe joint for joining first and second pipes together, the pipe joint comprising:
 an annular first coupler having a first longitudinal axis, the first coupler being mounted to or formed in a first end of the first pipe, and an annular second coupler having a second longitudinal axis, the second coupler being formed in or mounted to a second end of the second pipe; 
 the first coupler comprising a first distal end, an annular first outer wall and an annular first inner wall, the first distal end defining a first pipe receiving opening; 
 the second coupler comprising a second distal end, an annular second outer wall and an annular second inner wall, the second distal end and second coupler being sized for insertion into the first pipe receiving opening and into the first coupler to join the first and second pipes together, the second distal end defining a second pipe opening; 
 the first inner wall comprising a first set of interfitting features and the second outer wall comprising a second set of interfitting features, the first set of interfitting features surrounding and interfitting with the second set of interfitting features to join the first and second pipes together; 
 the first set of interfitting features comprising a first coupler first transition region spaced from the first distal end, a first coupler second transition region spaced further from the first distal end than the first coupler first transition region, and at least one intermediate first coupler transition region between the first coupler first transition region and the first coupler second transition region; wherein each of the first coupler first transition region, first coupler second transition region and at least one intermediate first coupler transition region are coaxial with the first longitudinal axis; a first shelf positioned further from the first distal end than the first coupler second transition region and having a first shelf surface that faces the first pipe receiving opening; wherein the first coupler first transition region comprises a first coupler first tooth having a first coupler first tooth surface defined at a location in the first coupler first transition region where the first coupler first transition region has an increased radius from the first longitudinal axis and wherein the first coupler first tooth surface faces the first shelf surface; wherein the first coupler second transition region comprises a first coupler second tooth having a first coupler second tooth surface defined at a location in the first coupler second transition region where the first coupler second transition region has an increased radius from the first longitudinal axis and wherein the first coupler second tooth surface faces the first shelf surface; and wherein each of the at least one first coupler intermediate transition region comprises a first coupler intermediate tooth having a first coupler intermediate tooth surface defined at a location in the first coupler intermediate transition region where the first coupler intermediate transition region has an increased radius from the first longitudinal axis and wherein the first coupler intermediate tooth surface faces the first shelf surface; 
 the first set of interfitting features further comprising a first coupler first ramp with a first coupler first ramp surface between the first distal end and the first coupler first transition region, a first coupler second ramp with a first coupler second ramp surface between the first coupler first transition region and the first shelf, and first coupler intermediate ramps, each first coupler intermediate ramp having a respective first coupler intermediate ramp surface, the first coupler intermediate ramps being positioned at opposite sides of each of the at least one first coupler intermediate transition region; and wherein the first coupler first ramp surface has a first coupler first ramp surface slope moving in a direction away from the first shelf, the first coupler second ramp surface has a first coupler second ramp surface slope moving in a direction away from the first shelf, and wherein the first coupler intermediate ramp surfaces each have a respective first coupler intermediate ramp surface slope moving in a direction away from the first shelf; 
 the second set of interfitting features comprising a second coupler first transition region spaced from the second distal end, a second coupler second transition region spaced from the second distal end and positioned further from the second distal end than the second coupler first transition region, and at least one intermediate second coupler transition region between the second coupler first transition region and the second coupler second transition region, each of the second coupler first transition region, second coupler second transition region and at least one intermediate second coupler transition region being coaxial with the second longitudinal axis; a second shelf positioned further from the second distal end than the second coupler second transition region and having a second shelf surface that faces the second pipe opening; wherein the second coupler first transition region comprises a second coupler first tooth having a second coupler first tooth surface defined at a location in the second coupler first transition region where the second coupler first transition region has a decreased radius from the second longitudinal axis and wherein the second coupler first tooth surface faces the second shelf surface; wherein the second coupler second transition region comprises a second coupler second tooth having a second coupler second tooth surface defined at a location in the second coupler second transition region where the second coupler second transition region has a decreased radius from the second longitudinal axis and wherein the second coupler second tooth surface faces the second shelf surface; and wherein each of the at least one second coupler intermediate transition region comprises a second coupler intermediate tooth having a second coupler intermediate tooth surface defined at a location in the second coupler intermediate transition region where the second coupler intermediate transition region has a decreased radius from the second longitudinal axis and wherein the second coupler intermediate tooth surface faces the second shelf surface; 
 the second set of interfitting features further comprising a second coupler first ramp with a second coupler first ramp surface between the second distal end and the second coupler first transition region, a second coupler second ramp with a second coupler second ramp surface between the second coupler first transition region and the second shelf, and second coupler intermediate ramps, each second coupler intermediate ramp having a respective second coupler intermediate ramp surface, the second coupler intermediate ramps being positioned at opposite sides of each of the at least one second coupler intermediate transition region; and wherein the second coupler first ramp surface has a second coupler first ramp surface slope moving in a direction away from the second distal end, the second coupler second ramp surface has a second coupler second ramp surface slope moving in a direction away from the second distal end, and wherein the second coupler intermediate ramp surfaces each have a second coupler intermediate ramp surface slope moving in a direction away from the second distal end; 
 wherein the first coupler first ramp surface slope, the first coupler second ramp surface slope, the first coupler intermediate ramp surface slope, the second coupler first ramp surface slope, the second coupler second ramp surface slope, and the second coupler intermediate ramp surface slope are each positive and less than 0.1; and 
 wherein the second coupler second ramp surface slope is less than the first coupler first ramp surface slope. 
 
     
     
       17. An apparatus The pipe joint according to  claim 16  wherein the first coupler first ramp surface slope is greater than the first coupler second ramp surface slope, and wherein the second coupler first ramp surface slope is less than the second coupler second ramp surface slope. 
     
     
       18. An apparatus The pipe joint according to  claim 16  wherein the first coupler second ramp surface slope is approximately one-third the first coupler first ramp surface slope. 
     
     
       19. An apparatus The pipe joint according to  claim 16  wherein the second coupler second ramp surface slope is approximately twenty percent less than the first coupler first ramp surface slope. 
     
     
       20. An apparatus The pipe joint according to  claim 16  wherein the first coupler first ramp surface slope and the first coupler intermediate ramp surface slope are from 0.05 to 0.08 and wherein the first coupler second ramp surface slope is from 0.01 to 0.04; and wherein the second coupler first ramp surface slope is from 0.01 to 0.04 and the second coupler second ramp surface slope and the second coupler intermediate ramp surface slope are from 0.05 to 0.08. 
     
     
       21. An apparatus The pipe joint according to  claim 16  wherein the second coupler intermediate ramp surface slope is the same or approximately the same for each second coupler intermediate ramp and less than the second coupler second ramp surface slope, and wherein the second coupler second ramp surface slope and second coupler intermediate ramp slope are greater than the second coupler first ramp surface slopes. 
     
     
       22. An apparatus The pipe joint according to  claim 21  wherein the first coupler intermediate ramp surface slope is the same or approximately the same for each first coupler intermediate ramp and greater than the first coupler first ramp surface slope and greater than the first coupler second ramp surface slope, and wherein the first coupler second ramp surface slope is less than the first coupler second ramp surface slope. 
     
     
       23. An apparatus The pipe joint according to  claim 16  wherein each of the first coupler first ramp, first coupler second ramp and first coupler intermediate ramps are frustoconical and coaxial with the first longitudinal axis; and wherein each of the second coupler first ramp, second coupler second ramp and second coupler intermediate ramps are frustoconical and coaxial with the second longitudinal axis. 
     
     
       24. An apparatus The pipe joint according to  claim 16  wherein the tooth depth of each tooth is equal to the height of the tooth surface in the radial direction and ranges from approximately 0.03 to 0.04 inches. 
     
     
       25. An apparatus The pipe joint according to  claim 16  wherein the tooth depth of each tooth is equal to the height of the tooth surface in the radial direction and is determined by the formula: Tooth or transition depth is equal to or approximately equal to: [[(pipe diameter/24)*0.005]+0.025], wherein * indicates multiplication and the pipe diameter is in inches. 
     
     
       26. An apparatus The pipe joint according to  claim 16  wherein a respective first coupler first annular surface of a constant diameter and coaxial with the first longitudinal axis is positioned at the side of each tooth of the first coupler nearest to the first distal end and a respective first coupler second annular surface of a constant diameter and coaxial with the first longitudinal axis is positioned at the side of each tooth of the first coupler nearest to the first shelf, wherein a respective second coupler first annular surface of a constant diameter and coaxial with the second longitudinal axis is positioned at the side of each tooth of the second coupler nearest to the second distal end and a respective second coupler second annular surface of a constant diameter and coaxial with the second longitudinal axis is positioned at the side of each tooth of the second coupler nearest to the second shelf, wherein the widths of the first coupler first annular surfaces in the longitudinal direction are less than the widths of the first coupler second annular surfaces in the longitudinal direction; and wherein the widths of the second coupler first annular surfaces in the longitudinal direction are less than the widths of the second coupler second annular surfaces in the longitudinal direction. 
     
     
       27. An apparatus The pipe joint according to  claim 26  wherein each of the first coupler first rampsections, first coupler second rampsection, first coupler intermediate rampsections, second coupler first rampsection, second coupler second rampsection, and second coupler intermediate ramp sections each have the same length in the longitudinal direction and wherein the first coupler first annular surfaces and second coupler first annular surfaces have a length in the longitudinal direction that is approximately five to ten percent of the length of the ramp sections ramps. 
     
     
       28. An apparatus The pipe joint according to  claim 16  wherein the first coupler comprises a first coupler base section extending from the first shelf to the first coupler second ramp section and having a first coupler base section axial length, the first coupler also comprising a first coupler entrance section extending from the first distal end to the first coupler first ramp section and having a first coupler entrance section axial length, the first coupler base section having an axial length that is longer than the axial length of the first coupler entrance section; and
 wherein the second coupler comprises a second coupler base section extending from the second shelf to the second coupler second ramp section and having a second coupler base section axial length, the second coupler also comprising a second coupler entrance section extending from the second distal end to the second coupler first ramp section and having a second coupler entrance section axial length, the second coupler base section having an axial length that is longer than the axial length of the second coupler entrance section. 
 
     
     
       29. An apparatus The pipe joint according to  claim 28  wherein the first coupler base section axial length is the same as the second coupler base section axial length and the first coupler entrance section axial length is the same as the second coupler entrance section axial length. 
     
     
       30. An apparatus The pipe joint according to  claim 16  wherein the diameter of the second coupler at the location of the second coupler first tooth at the second coupler first transition region is less than or equal to the diameter of the first coupler first tooth at the location of the first coupler first transition region. 
     
     
       31. An apparatus The pipe joint according to  claim 16  wherein the first and second pipes have respective first and second ends, the first coupler comprises a first ring adapted to be mounted to a first end of the first pipe and the second coupler comprises a second ring adapted to be mounted to the second end of the second pipe. 
     
     
       32. A pipe ram joint according to  claim 16  wherein the first and second pipes have respective first and second ends, a first of the first couplers being formed in or mounted to the first end of the first pipe and a second of the first couplers being formed in or mounted to the first end of the second pipe; and a first of the second couplers being formed in or mounted to the second end of the first pipe and a second of the second couplers being formed in or mounted to the second end of the second pipe. 
     
     
       33. A pipe joint comprising:
 a first coupler with an inner wall surface and a first set of interfitting first coupler features on the inner wall surface, the first coupler comprising a first distal end defining a coupler receiving opening;   a second coupler with an outer wall surface and a second set of interfitting second coupler features on the outer wall surface, the second coupler comprising a second distal end, the first and second coupler features being sized and positioned to engage one another to join the first and second couplers together when the second coupler is inserted into the coupler receiving opening of the first coupler;   the first coupler features comprising a first coupler first tooth spaced from the first distal end, a first coupler second tooth spaced from the first distal end, and a first coupler intermediate tooth spaced from the first distal end and positioned between the first coupler first and second teeth, the first coupler second tooth being positioned further from the first distal end than the first coupler first tooth;   the second coupler features comprising a second coupler first tooth spaced from the second distal end, a second coupler second tooth spaced from the second distal end, and a second coupler intermediate tooth spaced from the second distal end and positioned between the second coupler first and second teeth, the second coupler second tooth being positioned further from the second distal end than the second coupler first tooth;   the first coupler features comprising a first coupler first ramp nearest the first distal end, a first coupler second ramp positioned further from the first distal end than the first coupler second tooth, and a first coupler intermediate ramp between the first coupler intermediate tooth and the first coupler second tooth;   the second coupler features comprising a second coupler first ramp between the second coupler first tooth and the second distal end, a second coupler second ramp positioned further from the second distal end than the second coupler intermediate tooth, and a second coupler intermediate ramp between the second coupler first tooth and the second coupler intermediate tooth;   wherein the first coupler first ramp has a first coupler first ramp surface with a first coupler first ramp surface slope and the first coupler second ramp has a first coupler second ramp surface with a first coupler second ramp surface slope, and wherein the first coupler first ramp surface slope is greater than the first coupler second ramp surface slope;   wherein the second coupler first ramp has a second coupler first ramp surface with a second coupler first ramp surface slope and the second coupler second ramp has a second coupler second ramp surface with a second coupler second ramp surface slope, and wherein the second coupler first ramp surface slope is less than the second coupler second ramp surface slope.    
     
     
       34. The pipe joint according to  claim 33 , wherein the first coupler comprises a chamfer adjacent the first distal end.  
     
     
       35. The pipe joint according to  claim 33 , wherein the second coupler comprises a chamfer adjacent the second distal end.  
     
     
       36. The pipe joint according to  claim 33 , wherein the second coupler intermediate ramp has a second coupler intermediate ramp surface with a second coupler intermediate ramp surface slope, and wherein the second coupler second ramp surface slope and the second coupler intermediate ramp surface slope are each greater than the second coupler first ramp surface slope.  
     
     
       37. The pipe joint according to  claim 33 , wherein the first coupler intermediate ramp has a first coupler intermediate ramp surface with a first coupler intermediate ramp surface slope, and the first coupler second ramp surface slope is less than the first coupler intermediate ramp surface slope.  
     
     
       38. The pipe joint of  claim 33 , wherein the first coupler further comprises:
 a first shelf spaced further from the first distal end than the first coupler second tooth; and   from the first distal end in a direction toward the first shelf, a first coupler entrance section having a first inwardly facing cylindrical surface, a second inwardly facing cylindrical surface closer to the first shelf than the first inwardly facing cylindrical surface, a third inwardly facing cylindrical surface closer to the first shelf than the second inwardly facing cylindrical surface, and a fourth inwardly facing cylindrical surface closer to the first shelf than the third inwardly facing cylindrical surface;   wherein the first inwardly facing cylindrical surface, the second inwardly facing cylindrical surface, the third inwardly facing cylindrical surface, and the fourth inwardly facing cylindrical surface have radii measured from a longitudinal axis of the first coupler, and wherein the radius of the second inwardly facing cylindrical surface is greater than the radius of the fourth inwardly facing cylindrical surface.    
     
     
       39. The pipe joint according to  claim 33 , wherein the first coupler comprises a first shelf spaced further from the first distal end than the first coupler second tooth, the second coupler comprises a second shelf spaced further from the second distal end than the second coupler second tooth, and when the second coupler is fully engaged with the first coupler the first distal end of the first coupler abuts the second shelf of the second coupler and the second distal end of the second coupler abuts the first shelf of the first coupler.  
     
     
       40. A pipe joint comprising:
 a first coupler with an inner wall surface and a first set of interfitting first coupler features on the inner wall surface, the first coupler comprising a first distal end defining a coupler receiving opening;   a second coupler with an outer wall surface and a second set of interfitting second coupler features on the outer wall surface, the second coupler comprising a second distal end, the first and second coupler features being sized and positioned to engage one another to join the first and second couplers together when the second coupler is inserted into the coupler receiving opening of the first coupler;   the first coupler features comprising a first coupler first tooth spaced from the first distal end and positioned in a first coupler first transition region, a first coupler second tooth positioned in a first coupler second transition region, and a first coupler intermediate tooth spaced from the first distal end and positioned in a first coupler intermediate transition region positioned between the first coupler first and second transition regions, the first coupler second transition region being positioned further from the first distal end than the first coupler first transition region;   the second coupler features comprising a second coupler first tooth spaced from the second distal end and positioned in a second coupler first transition region, a second coupler second tooth positioned in a second coupler second transition region, and a second coupler intermediate tooth spaced from the second distal end and positioned in a second coupler intermediate transition region positioned between the second coupler first and second transition regions, the second coupler second transition region being positioned further from the second distal end than the second coupler first transition region;   the first coupler features comprising a first coupler first ramp nearest the first distal end, a first coupler second ramp positioned further from the first distal end than the first coupler second tooth, and a first coupler intermediate ramp between the first coupler intermediate tooth and the first coupler second tooth;   the second coupler features comprising a second coupler first ramp between the second coupler first tooth and the second distal end, a second coupler second ramp positioned further from the second distal end than the second coupler intermediate tooth, and a second coupler intermediate ramp between the second coupler first tooth and the second coupler intermediate tooth;   wherein the first coupler first ramp has a first coupler first ramp surface with a first coupler first ramp surface slope and the first coupler second ramp has a first coupler second ramp surface with a first coupler second ramp surface slope, and wherein the first coupler first ramp surface slope is greater than the first coupler second ramp surface slope;   wherein the second coupler first ramp has a second coupler first ramp surface with a second coupler first ramp surface slope and the second coupler second ramp has a second coupler second ramp surface with a second coupler second ramp surface slope, and wherein the second coupler first ramp surface slope is less than the second coupler second ramp surface slope.    
     
     
       41. The pipe joint according to  claim 40 , wherein the first coupler comprises a chamfer adjacent the first distal end.  
     
     
       42. The pipe joint according to  claim 40 , wherein the second coupler comprises a chamfer adjacent the second distal end.  
     
     
       43. The pipe joint according to  claim 40 , wherein the second coupler intermediate ramp has a second coupler intermediate ramp surface with a second coupler intermediate ramp surface slope, and wherein the second coupler second ramp surface slope and the second coupler intermediate ramp surface slope are each greater than the second coupler first ramp surface slope.  
     
     
       44. The pipe joint according to  claim 40 , wherein the first coupler intermediate ramp has a first coupler intermediate ramp surface with a first coupler intermediate ramp surface slope, and the first coupler second ramp surface slope is less than the first coupler intermediate ramp surface slope.  
     
     
       45. The pipe joint of  claim 40 , wherein the first coupler further comprises:
 a first shelf spaced further from the first distal end than the first coupler second tooth; and   from the first distal end in a direction toward the first shelf, a first coupler entrance section having a first inwardly facing cylindrical surface, a second inwardly facing cylindrical surface closer to the first shelf than the first inwardly facing cylindrical surface, a third inwardly facing cylindrical surface closer to the first shelf than the second inwardly facing cylindrical surface, and a fourth inwardly facing cylindrical surface closer to the first shelf than the third inwardly facing cylindrical surface;   wherein the first inwardly facing cylindrical surface, the second inwardly facing cylindrical surface, the third inwardly facing cylindrical surface, and the fourth inwardly facing cylindrical surface have radii measured from a longitudinal axis of the first coupler, and wherein the radius of the second inwardly facing cylindrical surface is greater than the radius of the fourth inwardly facing cylindrical surface.    
     
     
       46. The pipe joint according to  claim 40 , wherein the first coupler comprises a first shelf spaced further from the first distal end than the first coupler second tooth, the second coupler comprises a second shelf spaced further from the second distal end than the second coupler second tooth, and when the second coupler is fully engaged with the first coupler the first distal end of the first coupler abuts the second shelf of the second coupler and the second distal end of the second coupler abuts the first shelf of the first coupler.  
     
     
       47. A pipe joint, comprising:
 a female coupler mounted to or formed in a first end of a first pipe, the female coupler comprising an inner wall surface and a set of coupler features on the inner wall surface, the female coupler comprising a distal end defining a coupler receiving opening;   the coupler features comprising a first tooth spaced from the distal end and positioned in a first transition region, a second tooth positioned in a second transition region, and an intermediate tooth spaced from the distal end and positioned in an intermediate transition region positioned between the first and second transition regions, the second transition region being positioned further from the distal end than the first transition region;   the coupler features comprising a first ramp nearest to the distal end, a second ramp positioned further from the distal end than the second tooth, and an intermediate ramp between the intermediate tooth and the second tooth;   wherein the first ramp has a first ramp surface with a first ramp surface slope and the second ramp has a second ramp surface with a second ramp surface slope, and wherein the first ramp surface slope is greater than the second ramp surface slope; and   a male coupler mounted to or formed in an end of a second pipe, the male coupler being sized for insertion into the female coupler of the first pipe to join the first and second pipes together.    
     
     
       48. The pipe joint according to  claim 47 , wherein the female coupler comprises a chamfer adjacent the distal end.  
     
     
       49. The pipe joint according to  claim 47 , wherein the intermediate ramp has an intermediate ramp surface with an intermediate ramp surface slope, and the second ramp surface slope is less than the first coupler intermediate ramp surface slope.  
     
     
       50. The pipe joint according to  claim 47 , wherein the female coupler further comprises:
 a first shelf spaced further from the distal end than the second tooth; and   from the distal end in a direction toward the first shelf, an entrance section having a first inwardly facing cylindrical surface, a second inwardly facing cylindrical surface closer to the first shelf than the first inwardly facing cylindrical surface, a third inwardly facing cylindrical surface closer to the first shelf than the second inwardly facing cylindrical surface, and a fourth inwardly facing cylindrical surface closer to the first shelf than the third inwardly facing cylindrical surface;   wherein the first inwardly facing cylindrical surface, the second inwardly facing cylindrical surface, the third inwardly facing cylindrical surface, and the fourth inwardly facing cylindrical surface have radii measured from a longitudinal axis of the female coupler, and wherein the radius of the second inwardly facing cylindrical surface is greater than the radius of the fourth inwardly facing cylindrical surface.    
     
     
       51. A pipe joint, comprising:
 a male coupler mounted to or formed in a first end of a first pipe, the male coupler comprising an outer wall surface and a set of coupler features on the outer wall surface, the male coupler comprising a distal end;   the coupler features comprising a first tooth spaced from the distal end and positioned in a first transition region, a second tooth positioned in a second transition region, and an intermediate tooth spaced from the distal end and positioned in an intermediate transition region positioned between the first and second transition regions, the second transition region being positioned further from the distal end than the first transition region;   the coupler features comprising a first ramp between the first tooth and the distal end, a second ramp positioned further from the distal end than the intermediate tooth, and an intermediate ramp between the first tooth and the intermediate tooth;   wherein the first ramp has a first ramp surface with a first ramp surface slope and the second ramp has a second ramp surface with a second ramp surface slope, and wherein the first ramp surface slope is less than the second ramp surface slope; and   a female coupler mounted to or formed in an end of a second pipe, the male coupler being sized for insertion into the female coupler of the second pipe to join the first and second pipes together.    
     
     
       52. The pipe joint according to  claim 51 , wherein the male coupler comprises a chamfer adjacent the second distal end.  
     
     
       53. The pipe joint according to  claim 51 , wherein the intermediate ramp has an intermediate ramp surface with an intermediate ramp surface slope, and wherein the second ramp surface slope and the intermediate ramp surface slope are each greater than the first ramp surface slope.  
     
     
       54. A pipe joint comprising:
 a male coupler comprising:
 an outer wall surface and an inner wall surface 
 a distal end and a proximal end; and 
 a first tooth positioned closest to the distal end on the outer wall surface, and at least one second tooth on the outer wall surface; 
 wherein the first tooth includes, in a direction from the distal end toward the proximal end, a first inwardly facing cylindrical surface, a first ramp having a first ramp surface with a radius that progressively increases in a direction toward the proximal end, a second inwardly facing cylindrical surface parallel to the axial direction, and a first tooth surface extending in a radial direction of the pipe joint, 
 wherein the at least one second tooth includes, in a direction from the distal end toward the proximal end, a third inwardly facing cylindrical surface, a second ramp having a second ramp surface with a radius that progressively increases in a direction toward the proximal end, a fourth inwardly facing cylindrical surface, and a second tooth surface extending in the radial direction, 
 wherein the first inwardly facing cylindrical surface, the second inwardly facing cylindrical surface, the third inwardly facing cylindrical surface, and the fourth inwardly facing cylindrical surface each have a radius measured from a longitudinal axis of the pipe joint, and wherein the radius of the fourth inwardly facing cylindrical surface is greater than the radius of the second inwardly facing cylindrical surface, the radius of the second inwardly facing cylindrical surface is greater than the radius of the first inwardly facing cylindrical surface, and the radius of the first inwardly facing cylindrical surface is greater than the radius of the third inwardly facing cylindrical surface, and 
 wherein the first ramp surface has a first ramp surface slope relative to the longitudinal axis, the second ramp surface has a second ramp surface slope relative to the longitudinal axis, and the first ramp surface slope is less than the second ramp surface slope; and 
   a female coupler, comprising:
 an outer wall surface and an inner wall surface 
 a distal end and a proximal end; and 
 a first tooth positioned closest to the proximal end on the inner wall surface, and at least one second tooth on the inner wall surface; 
 wherein the first tooth includes, in a direction from the proximal end toward the distal end, a first inwardly facing cylindrical surface, a first ramp having a first ramp surface with a radius that progressively decreases in a direction toward the distal end, a second inwardly facing cylindrical surface, and a first tooth surface extending in the radial direction, 
 wherein the at least one second tooth includes, in a direction from the proximal end toward the distal end, a third inwardly facing cylindrical surface, a second ramp having a second ramp surface with a radius that progressively decreases in a direction toward the distal end, a fourth inwardly facing cylindrical surface, and a second tooth surface extending in the radial direction, 
 wherein the first inwardly facing cylindrical surface, the second inwardly facing cylindrical surface, the third inwardly facing cylindrical surface, and the fourth inwardly facing cylindrical surface each have a radius measured from the longitudinal axis, and wherein the radius of the third inwardly facing cylindrical surface is less than the radius of the first inwardly facing cylindrical surface, and the radius of the first inwardly facing cylindrical surface is less than the radius of the second inwardly facing cylindrical surface, and the radius of the second inwardly facing cylindrical surface is less than the radius of the fourth inwardly facing cylindrical surface, and 
 wherein the first ramp surface has a first ramp surface slope, the second ramp surface has a second ramp surface slope, and wherein the first ramp surface slope is less than the second ramp surface slope.  
   
     
     
       55. The pipe joint according to  claim 54 , wherein:
 the male coupler comprises at least two second teeth and the female coupler comprises at least two second teeth; and   when the male coupler is fully engaged with the female coupler, the at least two second teeth of the male coupler engage the at least two second teeth of the female coupler.    
     
     
       56. The pipe joint according to  claim 54 , wherein:
 the male coupler comprises a proximal shelf parallel to a radial direction and a distal end parallel to the radial direction;   the female coupler comprises a proximal shelf parallel to the radial direction and a distal end parallel to the radial direction; and   when the male coupling is fully engaged with the female coupling, the male coupler proximal shelf is adjacent the female coupler distal end and the male coupler distal end is adjacent the female coupler proximal shelf.    
     
     
       57. The pipe joint according to  claim 54 , wherein the female coupler comprises a chamfer adjacent the distal end, and the male coupler comprises a chamfer adjacent the distal end.  
     
     
       58. A pipe joint, comprising:
 female coupling means for coupling to male coupling means, the female coupling means being mounted to or formed in a first end of a first pipe, the female coupling means comprising an inner wall surface and interfitting feature means on the inner wall surface, the female coupling means comprising a distal end defining a coupler receiving opening;   the interfitting feature means comprising a first tooth means spaced from the distal end, a second tooth, and an intermediate tooth spaced from the distal end and positioned between the first and second tooth, the second tooth being positioned further from the distal end than the first tooth;   the interfitting feature means comprising a first ramp nearest to the distal end, a second ramp positioned further from the distal end than the second tooth, and an intermediate ramp between the intermediate tooth and the second tooth;   wherein the first ramp has a first ramp surface with a first ramp surface slope and the second ramp has a second ramp surface with a second ramp surface slope, and wherein the first ramp surface slope is greater than the second ramp surface slope; and   male coupling means for coupling to the female coupling means, the male coupling means being mounted to or formed in an end of a second pipe, the male coupling means being sized for insertion into the female coupling means of the first pipe to join the first and second pipes together.   
     
     
       59. The pipe joint according to  claim 58 , wherein the female coupling means comprises chamfer means adjacent the first distal end.  
     
     
       60. The pipe joint according to  claim 58 , wherein the intermediate ramp has an intermediate ramp surface with an intermediate ramp surface slope, and the second ramp surface slope is less than the intermediate ramp surface slope.  
     
     
       61. The pipe joint of  claim 58 , wherein the female coupling means further comprises:
 first shelf means for abutting a distal end of the male coupling means, the first shelf means spaced further from the distal end than the second tooth; and   from the distal end in a direction toward the first shelf means, an entrance section having a first inwardly facing cylindrical surface, a second inwardly facing cylindrical surface closer to the first shelf means than the first inwardly facing cylindrical surface, a third inwardly facing cylindrical surface closer to the first shelf means than the second inwardly facing cylindrical surface, and a fourth inwardly facing cylindrical surface closer to the first shelf means than the third inwardly facing cylindrical surface;   wherein the first inwardly facing cylindrical surface, the second inwardly facing cylindrical surface, the third inwardly facing cylindrical surface, and the fourth inwardly facing cylindrical surface have radii measured from a longitudinal axis of the female coupling means, and wherein the radius of the second inwardly facing cylindrical surface is greater than the radius of the fourth inwardly facing cylindrical surface.   
     
     
       62. A method, comprising:
 advancing a first coupler of a first pipe over a second coupler of a second pipe such that the first coupler receives the second coupler in a coupler receiving opening of the first coupler to form a pipe joint,   the first coupler comprising:
 an inner wall surface and a set of first coupler features on the inner wall surface, the first coupler comprising a distal end defining the coupler receiving opening; 
 the first coupler features comprising a first coupler first tooth spaced from the distal end and positioned in a first coupler first transition region, a first coupler second tooth positioned in a first coupler second transition region, and a first coupler intermediate tooth spaced from the distal end and positioned in a first coupler intermediate transition region positioned between the first coupler first and second transition regions, the first coupler second transition region being positioned further from the distal end than the first coupler first transition region; 
 the first coupler features further comprising a first coupler first ramp nearest to the distal end, a first coupler second ramp positioned further from the distal end than the first coupler second tooth, and a first coupler intermediate ramp between the first coupler intermediate tooth and the first coupler second tooth; 
 wherein the first coupler first ramp has a first coupler first ramp surface with a first coupler first ramp surface slope and the first coupler second ramp has a first coupler second ramp surface with a first coupler second ramp surface slope, and wherein the first coupler first ramp surface slope is greater than the first coupler second ramp surface slope; and 
   the second coupler comprising:
 an outer wall surface and a set of second coupler features on the outer wall surface, the second coupler comprising a distal end; 
 the second coupler features comprising a second coupler first tooth spaced from the distal end and positioned in a second coupler first transition region, a second coupler second tooth positioned in a second coupler second transition region, and a second coupler intermediate tooth spaced from the distal end and positioned in a second coupler intermediate transition region positioned between the second coupler first and second transition regions, the second coupler second transition region being positioned further from the distal end than the second coupler first transition region; 
 the second coupler features further comprising a second coupler first ramp between the second coupler first tooth and the distal end, a second coupler second ramp positioned further from the distal end than the second coupler intermediate tooth, and a second coupler intermediate ramp between the second coupler first tooth and the second coupler intermediate tooth; 
 wherein the second coupler first ramp has a second coupler first ramp surface with a second coupler first ramp surface slope and the second coupler second ramp has a second coupler second ramp surface with a second coupler second ramp surface slope, and wherein the second coupler first ramp surface slope is less than the second coupler second ramp surface slope.  
   
     
     
       63. A pipe joint comprising:
 a male coupler comprising:
 an outer wall surface and an inner wall surface 
 a distal end and a proximal end; and 
 a first tooth positioned closest to the distal end on the outer wall surface, and at least one second tooth on the outer wall surface; 
 wherein the first tooth includes, in a direction from the distal end toward the proximal end, a first inwardly facing cylindrical surface, a first ramp having a first ramp surface with a radius that progressively increases in a direction toward the proximal end, a second inwardly facing cylindrical surface parallel to the axial direction, and a first tooth surface extending in a radial direction of the pipe joint, 
 wherein the at least one second tooth includes, in a direction from the distal end toward the proximal end, a third inwardly facing cylindrical surface, a second ramp having a second ramp surface with a radius that progressively increases in a direction toward the proximal end, a fourth inwardly facing cylindrical surface, and a second tooth surface extending in the radial direction, 
 wherein the first inwardly facing cylindrical surface, the second inwardly facing cylindrical surface, the third inwardly facing cylindrical surface, and the fourth inwardly facing cylindrical surface each have a radius measured from a longitudinal axis of the pipe joint, and wherein the radius of the second inwardly facing cylindrical surface is greater than the radius of the first inwardly facing cylindrical surface, and 
 wherein the first ramp surface has a first ramp surface slope relative to the longitudinal axis, the second ramp surface has a second ramp surface slope relative to the longitudinal axis, and the first ramp surface slope is less than the second ramp surface slope; and 
   a female coupler, comprising:
 an outer wall surface and an inner wall surface 
 a distal end and a proximal end; and 
 a first tooth positioned closest to the proximal end on the inner wall surface, and at least one second tooth on the inner wall surface; 
 wherein the first tooth includes, in a direction from the proximal end toward the distal end, a first inwardly facing cylindrical surface, a first ramp having a first ramp surface with a radius that progressively decreases in a direction toward the distal end, a second inwardly facing cylindrical surface, and a first tooth surface extending in the radial direction, 
 wherein the at least one second tooth includes, in a direction from the proximal end toward the distal end, a third inwardly facing cylindrical surface, a second ramp having a second ramp surface with a radius that progressively decreases in a direction toward the distal end, a fourth inwardly facing cylindrical surface, and a second tooth surface extending in the radial direction, 
 wherein the first inwardly facing cylindrical surface, the second inwardly facing cylindrical surface, the third inwardly facing cylindrical surface, and the fourth inwardly facing cylindrical surface each have a radius measured from the longitudinal axis, and wherein the radius of the first inwardly facing cylindrical surface is less than the radius of the second inwardly facing cylindrical surface, and 
 wherein the first ramp surface has a first ramp surface slope, the second ramp surface has a second ramp surface slope, and wherein the first ramp surface slope is less than the second ramp surface slope.