System, method and apparatus for expansion coupling for pipes

1. A coupling forming a joint with at least two pipes, the coupling comprising:

a coupling body having an axis, an axial length, an axial center, axial ends and an inner surface comprising an inner diameter that is substantially constant over an entirety of the axial length; and

a single shoulder protruding radially inward relative to the axis from the inner surface, such that the inner surface has no other shoulders, and the single shoulder is not axially aligned with the axial center of the coupling body,

wherein the coupling body comprises retainer grooves and seal grooves, each of the at least two pipes comprises only a pipe retainer groove but not a pipe seal groove, and the coupling is configured to retain the pipes with retainers in an installed configuration.

2. The coupling of claim 1 , wherein, in an installed configuration, the single shoulder is substantially in contact with only one of the at least two pipes, such that another of the at least two pipes is free of contact with the single shoulder.

3. The coupling of claim 1 , wherein an exterior of the coupling body comprises visual indicia to indicate a location of the single shoulder from the exterior of the coupling.

4. The coupling of claim 1 , wherein an axial centerline of the single shoulder is axially spaced apart from a first axial end by a first distance, the axial centerline of the single shoulder is axially spaced apart from a second axial end by a second distance, and the second distance is at least about twice the first distance.

5. The coupling of claim 1 , wherein the coupling comprises a straight coupling for only the at least two pipes or comprises a tee for the at least two pipes and a third pipe.

6. The coupling of claim 1 , wherein the single shoulder comprises a mechanical stop comprising one of a rectangular hard stop and a chamfered stop.

7. The coupling of claim 1 , wherein the coupling body is configured to freely axially release the at least two pipes from the axial ends from which the at least two pipes are configured to protrude.

8. The coupling of claim 1 , wherein the single shoulder is configured to limit axial insertion of the at least two pipes, such that the at least two pipes are configured to never make contact with each other inside the coupling due to the presence of the single shoulder.

9. The coupling of claim 1 , wherein the coupling body comprises an anchor configured to enhance movement of the coupling relative to the at least two pipes using tools.

10. The coupling of claim 1 , further comprising:

a first pipe axial insertion depth and a second pipe axial insertion depth of the at least two pipes, wherein the second pipe axial insertion depth is at least about double the first pipe axial insertion depth.

11. A pipe system, comprising:

a coupling having an axis, axial ends, an interior and an axial-facing portion in the interior; and

at least two pipes configured to be inserted into different axial ends of the coupling and secured therein with retainers, the axial-facing portion of the coupling is configured to substantially remain in contact with only one of the pipes, and another one of the pipes does not axially abut, either directly or indirectly, any axial-facing portion of the coupling in the installed position other than through a respective retainer, such that said another one of the pipes only radially abuts the coupling with respect to the axis.

12. The pipe system of claim 11 , wherein the coupling comprises an inner diameter that is substantially constant over an entirety of the axial length other than a retainer and a seal groove.

13. The pipe system of claim 11 , wherein the axial-facing portion is not axially aligned with an axial center of the coupling.

14. The pipe system of claim 11 , wherein an axial centerline of the axial-facing portion of the coupling is axially spaced apart from a first axial end of the coupling by a first distance, the axial centerline of the axial-facing portion is axially spaced apart from a second axial end of the coupling by a second distance, and the second distance is at least about twice the first distance.

15. The pipe system of claim 11 , wherein the axial-facing portion comprises a mechanical stop that is chamfered in both axial directions.

16. The pipe system of claim 11 , wherein the coupling body is configured to freely axially release the pipes from the axial ends from which the pipes are configured to protrude.

17. The pipe system of claim 11 , wherein the coupling comprises at least one of a seal groove and a retainer groove.

18. The pipe system of claim 11 , wherein the coupling comprises retainer grooves and seal grooves, each of the pipes comprises only a pipe retainer groove but not a pipe seal groove, and the coupling is configured to retain the pipes with splines in an installed configuration.

19. The pipe system of claim 11 , wherein the axial-facing portion is configured to limit axial insertion of both pipes, such that the pipes are configured to never make contact with each other inside the coupling due to the presence of the axial-facing portion.

20. The pipe system of claim 11 , wherein the pipes have a substantially constant outer diameter, other than axial tips thereof, which can be chamfered.

21. The pipe system of claim 11 , wherein the axial-facing portion can automatically align retainer grooves of the coupling and at least one of the pipes when said at least one of the pipes abuts the axial-facing portion.

22. The pipe system of claim 11 , wherein at least one of the pipes can be positioned in both an installed state and a disassembled state with respect to the coupling without said at least one of the pipes being axially repositioned.