Claims:

1. A pipe coupling for receiving, holding and releasing a pipe, comprising: a coupling body having a bore with a geometric axis into which a pipe can be inserted in a pipe insertion direction; a rotatable sleeve which is arranged at least partially around the coupling body and which is rotatable around the axis of the bore with respect to the coupling body; a gripping element configured to engage a surface of the pipe; a pipe release element configured to disengage the gripping element from the surface of the pipe upon axial movement of the pipe release element; and a release collar coupled to an end of the rotatable sleeve; wherein axial rotation of the rotatable sleeve in a first direction causes the release collar to move axially from a locked position to an unlocked position and wherein in the unlocked position, the release collar can be moved axially in the pipe insertion direction to cause the pipe release element to disengage the gripping element from the surface of the pipe.

2. The pipe coupling of claim 1, wherein axial rotation of the rotatable sleeve in a second direction causes the release collar to move axially from the unlocked position to the locked position.

3. The pipe coupling of claim 1 or 2, wherein the pipe release element has a threaded outer surface which engages with a threaded inner surface of the release collar.

4. The pipe coupling of any preceding claim, wherein the release collar is coupled to the rotatable sleeve such that the release collar rotates together with the rotatable sleeve.

5. The pipe coupling of any preceding claim, wherein the release collar is coupled to the rotatable sleeve such that the release collar can move axially with respect to the rotatable sleeve.

6. The pipe coupling of claim 4 or 5, wherein the release collar comprises a number of axial grooves or ridges to engage a number of axial ridges or grooves of the rotatable sleeve.

7. The pipe coupling of any preceding claim, wherein, when rotating the rotatable sleeve in a second direction, the rotatable sleeve provides tactile feedback when the release collar is in a locked position.

8. The pipe coupling of claim 7, wherein the rotatable sleeve comprises a first axial ridge and the coupling body comprises a second axial ridge arranged such that when rotating the rotatable sleeve in a second direction, the first axial ridge engages the second axial ridge to provide tactile feedback when the release collar is in a locked position.

9. The pipe coupling of any preceding claim, wherein, when rotating the rotatable sleeve in a first direction, the rotatable sleeve is prevented from further rotation when the release collar is in the unlocked position.

10. The pipe coupling of claim 9, wherein the rotatable sleeve comprises a first axial ridge and the coupling body comprises a third axial ridge arranged such that when rotating the rotatable sleeve in a first direction, the first axial ridge engages the third axial ridge to stop further rotation of the rotatable sleeve when the release collar is in the unlocked position.

11. The pipe coupling of any preceding claim, wherein the pipe release element is coupled to the coupling body to prevent rotational movement of the pipe release element with respect to the coupling body.

12. The pipe coupling of any preceding claim, wherein the pipe release element is coupled to the coupling body to allow axial movement of the pipe release element with respect to the coupling body.

13. The pipe coupling of any preceding claim, wherein the pipe release element comprises a number of axially aligned legs.

14. The pipe coupling of claim 13, wherein the axially aligned legs extend in the pipe insertion direction.

15. The pipe coupling of claim 13 or 14, wherein the gripping element is disposed on the legs of the pipe release element.

16. The pipe coupling of claim 15, wherein the gripping element comprises a number of teeth disposed on the legs of the pipe release element.

17. The pipe coupling of claim 16, wherein the teeth extend radially inwardly to engage an outer surface of the pipe.

18. The pipe coupling of claim 16 or 17, wherein the teeth are inclined in the pipe insertion direction.

19. The pipe coupling element of any of claims 16 to 18, wherein upon axial movement of the pipe release element in the pipe insertion direction, the legs of the pipe release 41 element expand radially outwards so as to disengage the teeth of the gripping element from the surface of the pipe.

20. The pipe coupling of any of any of claims 1 to 12, wherein the gripping element is separate from the pipe release element.

21. The pipe coupling of claim 20, wherein the gripping element is disposed adjacent the pipe release element.

22. The pipe coupling of claim 21, wherein the pipe release element and the gripping element are disposed sequentially in the pipe insertion direction.

23. The pipe coupling of any of claims 20 to 22, wherein the gripping element comprises a number of teeth extending radially inwardly to engage with an outer surface of the pipe.

24. The pipe coupling of claim 23, wherein the teeth are inclined in the pipe insertion direction.

25. The pipe coupling of any of claims 20 to 24, wherein at least one of the teeth comprises a first strengthening element, preferably a first flange, which extends along the majority of the length of the at least one of the teeth.

26. The pipe coupling of claim 25, wherein the first strengthening element is disposed along a first edge of the at least one of the teeth.

27. The pipe coupling of claim 25 or 26, wherein the at least one of the teeth comprises a second strengthening element, preferably a flange, which extends along the majority of the length of the at least one of the teeth. 42

28. The pipe coupling of claim 27, wherein the second strengthening element is disposed along a second edge of the at least one of the plurality of teeth.

29. The pipe coupling of any of claims 20 to 28, wherein the pipe release element has an outer surface which tapers in the pipe insertion direction.

30. The pipe coupling of claim 29, wherein the tapered surface of the pipe release element engages the teeth of the gripping element upon axial movement of the pipe release element in the pipe insertion direction to disengage the teeth of the gripping element from the surface of the pipe.

31. The pipe coupling of any preceding claim, wherein the pipe release element and the gripping element are arranged sequentially in the pipe insertion direction in a chamber defined by the rotatable sleeve.

32. The pipe coupling of any preceding claim, further comprising a connecting element for connecting the coupling body to the pipe release element.

33. The pipe coupling of claim 32, wherein the connecting element is coupled to the coupling body to prevent rotation of the connecting element with respect to the coupling body.

34. The pipe coupling of claim 32 or 33, wherein the connecting element is coupled to the coupling body to prevent axial movement of the connecting element with respect to the coupling body.

35. The pipe coupling of any of claims 32 to 34, wherein the coupling body comprises a number of tabs or slots to engage a number of corresponding slots or tabs of the connecting element. 43

36. The pipe coupling of any of claims 32 to 35, wherein the pipe release element is coupled to the connecting element to prevent rotation of the pipe release element.

37. The pipe coupling of any of claims 32 to 36, wherein the pipe release element is coupled to the connecting element to allow axial movement of the pipe release element with respect to the connecting element.

38. The pipe coupling of any of claims 32 to 37, wherein the pipe release element comprises a number of axial grooves or ridges to engage a number of corresponding axial ridges or grooves of the connecting element.

39. The pipe coupling of any of claims 32 to 38, wherein the connecting element limits the axial movement of the pipe release element in a direction opposite the pipe insertion direction.

40. The pipe coupling of any of claims 32 to 39, wherein the pipe release element, the connecting element and the gripping element are disposed sequentially in the pipe insertion direction in a chamber defined by the rotatable sleeve.

41. The pipe coupling of any preceding claim further comprising a sealing element for sealing a space between the pipe coupling and an outer surface of the pipe.

42. The pipe coupling of claim 41, wherein the pipe release element, the connecting element, the gripping element and the sealing element are disposed sequentially in the pipe insertion direction in a chamber defined by the rotatable sleeve. 44

43. The pipe coupling of claim 41 or 42, further comprising a spacer element disposed between the gripping element and the sealing element.

44. The pipe coupling of any preceding claim, wherein the bore is tubular and the pipe release element is a tubular pipe release element.

45. The pipe coupling of any preceding claim, wherein the coupling body has a first shoulder for limiting the pipe insertion length.

46. The pipe coupling of claim 45, wherein the first shoulder has a number of radially disposed ridges for interacting with a pipe insertion end.

47. A method of assembling a pipe coupling for receiving, holding and releasing a pipe, the method comprising: coupling a release collar to the end of a rotatable sleeve; coupling a pipe release element to the release collar to produce a first subassembly, wherein the rotatable sleeve and the release collar are rotatable with respect to the pipe release element; inserting a gripping element into a coupling body comprising a bore with a geometric axis into which a pipe can be inserted in a pipe insertion direction to produce a second subassembly; attaching the first subassembly to the second subassembly to produce a pipe coupling in which axial rotation of the rotatable sleeve in a first direction causes the release collar to move axially from a locked position to an unlocked position and in the unlocked position, the release collar can be moved axially in the pipe insertion direction to cause the pipe release element to disengage the gripping element from the surface of the pipe. 45

48. The method of claim 47, wherein coupling the pipe release element to the release collar comprises threadably engaging a threaded outer surface of the pipe release element with a threaded inner surface of the release collar.

49. The method of claim 47 or 48, wherein, before coupling the pipe release element to the release collar, the pipe release element is coupled to a connecting element.

50. The method of claim 49, wherein the pipe release element is coupled to the connecting element to prevent rotation of the pipe release element with respect to the connecting element.

51. The method of claim 49 or 50, wherein the pipe release element is coupled to the connecting element to allow axial movement of the pipe release element with respect to the connecting element.

52. The method of any of claims 47 to 51, wherein, before inserting the gripping element into the coupling body, a sealing element is inserted into the bore of the coupling body.

53. The method of claim 52, wherein after the sealing element is inserted into the coupling body, a spacer element is inserted into the bore of the coupling body.

54. A gripping element for a holding a pipe in a pipe coupling, comprising: an annular ring; a plurality of teeth for engaging an outer surface of the pipe, the plurality of teeth extending radially inwardly from the annular ring and inclined at an angle with respect to the annular ring, wherein at least one of the plurality of teeth comprises a first strengthening element which extends along the 46 majority of the length of the at least one of the plurality of teeth.

55. The gripping element of claim 54, wherein the first strengthening element is a flange.

56. The gripping element of claim 54 or 55, wherein the annular ring is in the form of a planar ring.

57. The gripping element of claim 55 or 56, wherein there is a gap between the end of the first flange and the annular ring.

58. The gripping element of any of claims 54 to 57, wherein the at least one of, preferably each of, the plurality of teeth is in the shape of a trapezoid.

59. The gripping element of claim 58, wherein the width of the at least one of, preferably each of, the plurality of teeth tapers in a direction radially inwards from a wider width to a narrower width.

60. The gripping element of any of claims 55 to 59, wherein the first flange is disposed along a first edge of the at least one of the plurality of teeth.

61. The gripping element of claim 60, wherein the first flange is disposed at an angle of 45 to 120 degrees, preferably at an angle of 60 to 90 degrees, to the at least one of the plurality of teeth.

62. The gripping element of any of claims 54 to 61, wherein the at least one of the plurality of teeth comprises a second strengthening element which extends along the majority of the length of the at least one of the plurality of teeth. 47

63. The gripping element of claim 62, wherein the second strengthening element is a second flange.

64. The gripping element of claim 63, wherein there is a gap between the end of the second flange and the annular ring.

65. The gripping element of claim 63 or 64, wherein the second flange is disposed along a second edge of the at least one of the plurality of teeth.

66. The gripping element of claim 63, 64 or 65, wherein the second flange is disposed at an angle of 15 to 90 degrees, preferably at an angle of 45 to 90 degrees, to the at least one of the plurality of teeth.

67. The gripping element of any of claims 54 to 66, wherein each of the plurality of teeth comprises the first strengthening element.

68. The gripping element of any of claims 54 to 67, wherein each of the plurality of teeth comprises the second strengthening element.

69. The gripping element of any of claims 54 to 68, wherein the gripping element is made from a metal.

70. A coupling body for receiving a pipe in a pipe coupling, the coupling body comprising: a bore with a geometric axis into which a pipe can be inserted in a pipe insertion direction; a first annular internal shoulder within the bore; a first annular external shoulder for engaging with a rotatable sleeve, the first annular external shoulder being offset from the first annular internal shoulder along the axis of the bore; and 48 an elongate annular portion which connects the first annular internal shoulder with the first annular external shoulder.

71. The coupling body of claim 70, wherein the first annular internal shoulder is suitable for receiving a sealing element or a gripping element.

72. The coupling body of claim 70 or 71, further comprising a second annular internal shoulder for accommodating an end of the pipe.

73. The coupling body of any of claims 70 to 72, further comprising a third annular internal shoulder for accommodating a spacer element.

74. The coupling body of claim 73, wherein the third annular internal shoulder is axially aligned with the first annular external shoulder.

75. A pipe coupling for receiving, holding and releasing a pipe, comprising: the coupling body of any of claims 70 or 74; a rotatable sleeve which is arranged at least partially around the coupling body and which is rotatable around the axis of the bore with respect to the coupling body, the rotatable sleeve having an annular groove which is engaged with the first annular external shoulder of the coupling body; a gripping element configured to engage a surface of the pipe; a pipe release element configured to disengage the gripping element from the surface of the pipe upon axial movement of the pipe release element.

76. The pipe coupling of claim 75, further comprising a sealing element for sealing a space between the pipe coupling 49 and an outer surface of the pipe, wherein the sealing element is in contact with the first annular internal shoulder of the coupling body.

77. The pipe coupling of claim 75 or 76, further comprising a spacer element which is in contact with the third annular internal shoulder of the coupling body and the gripping element.

78. The pipe coupling of any of claims 75 to 77, further comprising a release collar coupled to an end of the rotatable sleeve.

79. The pipe coupling of claim 78, wherein axial rotation of the rotatable sleeve in a first direction causes the release collar to move axially from a locked position to an unlocked position

80. The pipe coupling of claim 79, wherein in the unlocked position, the release collar can be moved axially in the pipe insertion direction to cause the pipe release element to disengage the gripping element from the surface of the pipe.