Coupling and Seal

Abstract

A mechanical coupling for joining pipe elements end to end has a channel that receives a ring seal. The channel is defined by oppositely disposed side surfaces and the ring seal has lobes on opposite sides. The lobes have surfaces facing the side surfaces of the channel. When the ring seal is seated within the channel, each lobe surface contacts a respective side surface such that the lobes deform inwardly toward the center of the channel.

Claims

1. A coupling for joining pipe elements in end to end relation, said coupling comprising: a plurality of segments attached to one another end to end and surrounding a central space, each of said segments having a channel extending circumferentially around and facing said central space, each of said channels being defined by first and second side surfaces located on opposite sides of said segments and a back surface extending between said side surfaces; a seal positioned within said central space, said seal comprising a ring having first and second lobes positioned on opposite sides thereof, said first lobe having a first lobe surface facing toward said first side surface and said second lobe having a second lobe surface facing toward said second side surface, said first lobe surface being oriented angularly with respect to said first side surface, and said second lobe surface being oriented angularly with respect to said second side surface when said seal is in an undeformed shape; wherein when said first and second lobes are engaged with said pipe elements, at least a portion of said first and second lobe surfaces are in contact with said side surfaces such that said lobes will deform toward a center of said channel when said ring is seated within said channel; and a connection member positioned at one end of each of said segments, said connection members on said segments being adjustably tightenable for drawing said segments toward one another and seating said ring within said channel, thereby deforming said seal.

2. A coupling for joining pipe elements in end to end relation, said coupling comprising: a plurality of segments attached to one another end to end and surrounding a central space, each of said segments having a channel extending circumferentially around and facing said central space, each of said channels being defined by first and second side surfaces located on opposite sides of said segments and a back surface extending between said side surfaces; a seal positioned within said central space, said seal comprising a ring having at least one lobe positioned on a side thereof, said at least one lobe having a lobe surface facing toward said first side surface, said lobe surface being oriented angularly with respect to said first side surface when said seal in in an undeformed shape; wherein when said at least one lobe is engaged with said pipe element, at least a portion of said lobe surface is in contact with said first side surface such that said at least one lobe will deform toward a center of said channel when said ring is seated within said channel; and connection members being positioned at opposite ends of each of said segments, said connection members being adjustably tightenable for drawing said segments toward one another and seating said ring within said channel, thereby deforming said at least one lobe.

3. A coupling for joining pipe elements in end to end relation, said coupling comprising: a plurality of segments attached to one another end to end and surrounding a central space, each of said segments having a channel extending circumferentially around and facing said central space, each of said channels being defined by first and second side surfaces located on opposite sides of said segments and a back surface extending between said side surfaces; a seal positioned within said central space, said seal comprising a ring having first and second lobes positioned on opposite sides thereof, said first lobe having a first lobe surface facing toward said first side surface and said second lobe having a second lobe surface facing toward said second side surface; wherein when said first and second lobes are engaged with said pipe elements said seal is in an undeformed state, at least a portion of said first and second lobe surfaces being wider than the widest distance between said first and second side surfaces such that said lobes will deform toward a center of said channel when said ring is seated within said channel; and connection members being positioned at opposite ends of each of said segments, said connection members being adjustably tightenable for drawing said segments toward one another and seating said ring within said channel, thereby deforming said lobes.

4. The coupling according to claim 3, wherein said first lobe surface is oriented angularly with respect to said first side surface and said second lobe surface is oriented angularly with respect to said second side surface when said seal is in said undeformed shape.

5. The coupling according to claim 3, wherein said first and second lobe surfaces comprises convexly curved surfaces when said seal is in said undeformed shape.

6. The coupling according to claim 5, wherein said first and second side surfaces comprise convexly curved surfaces.

7. The coupling according to claim 3, wherein said first and second side surfaces comprise convexly curved surfaces.

8. A coupling for joining pipe elements in end to end relation, said coupling comprising: a plurality of segments attached to one another end to end and surrounding a central space, each of said segments having a channel extending circumferentially around and facing said central space, each of said channels being defined by first and second side surfaces located on opposite sides of said segments and a back surface extending between said side surfaces; a seal positioned within said central space, said seal comprising a ring having first and second lobes positioned on opposite sides thereof, said first lobe having a first lobe surface facing toward said first side surface and said second lobe having a second lobe surface facing toward said second side surface; a first gland attached to said first lobe and a second gland attached to said second lobe, said first and second glands extending circumferentially about said ring, said first gland having a first sealing surface, said second gland having a second sealing surface, said first and second sealing surfaces facing said central space; wherein when said sealing surfaces are engaged with said pipe element, said first lobe surface is oriented angularly with respect to said first side surface and said second lobe surface is oriented angularly with respect to said second side surface such that said lobes will deform toward a center of said channel when said ring is seated within said channel; and connection members being positioned at opposite ends of each of said segments, said connection members being adjustably tightenable for drawing said segments toward one another and seating said ring within said channel, thereby deforming said lobes.

9. The coupling according to claim 8, wherein said connection members on each of said segments comprise a pair of projections, one said projection being positioned on each of said opposite ends of said segments, said projections having holes to receive a fastener, said fastener being adjustably tightenable.

10. The coupling according to claim 8, wherein said coupling comprises two of said segments.

11. The coupling according to claim 8, wherein said first lobe surface has an orientation angle relative to said first side surface from 1 to 20.

12. The coupling according to claim 11, wherein said orientation angle of said first lobe surface is 8.

13. The coupling according to claim 11, wherein said second lobe surface has an orientation angle relative to said second side surface from 1 to 20.

14. The coupling according to claim 13, wherein said orientation angle of said second lobe surface is 8.

15. The coupling according to claim 8, wherein said second lobe surface has an orientation angle relative to said second side surface from 1 to 20.

16. The coupling according to claim 15, wherein said orientation angle of said second lobe surface is 8.

17. The coupling according to claim 8, wherein said seal is formed of a rubber material.

18. The coupling according to claim 8, wherein said seal is formed of a material having low elasticity.

19. The coupling according to claim 18, wherein said seal is formed of a material having an elastic limit from 0.05% to 20%.

20. The coupling according to claim 18, wherein said seal is formed of a material having an elastic limit from 0.5% to 10%.

21. The coupling according to claim 18, wherein said seal is formed of a material having an elastic limit from 1% to 5%.

22. The coupling according to claim 18, wherein said material having low elasticity is selected from the group consisting of thermoplastic resins, thermosets, epoxies and composites including polyethylene, polypropylene, polyamides, polyvinyl chloride, polycarbonate, polystyrene, acetals, acrylics, fluoropolymers and combinations thereof.

23. The coupling according to claim 8, wherein each of said segments further comprises first and second keys positioned on opposite sides of said segments, each of said keys extending circumferentially around and projecting toward an axis extending through said central space.

24. The coupling according to claim 23, wherein said first keys on each of said segments are positioned in spaced relation to said first side surfaces of said segments.

25. The coupling according to claim 24, wherein said second keys on each of said segments are positioned in spaced relation to said second side surfaces of said segments.

26. The coupling according to claim 23, wherein each of said keys comprises an arcuate surface facing said axis.

27. The coupling according to claim 8, further comprising: a first spring element positioned on said first gland opposite to said first sealing surface; a second spring element positioned on said second gland opposite to said second sealing surface, said spring elements extending circumferentially around said ring and biasing said first and second sealing surfaces toward said central space.

28. In combination, first and second pipe elements and a coupling for joining said pipe elements in end to end relation, said coupling comprising: a plurality of segments attached to one another end to end and surrounding a central space, said pipe elements being received within said central space, each of said segments having a channel extending circumferentially around and facing said central space, each of said channels being defined by first and second side surfaces located on opposite sides of said segments and a back surface extending between said side surfaces; a seal positioned within said central space, said seal comprising a ring surrounding said pipe elements, said ring having first and second lobes positioned on opposite sides thereof, said first lobe having a first lobe surface facing toward said first side surface and said second lobe having a second lobe surface facing toward said second side surface; a first gland attached to said first lobe and a second gland attached to said second lobe, said first and second glands extending circumferentially about said ring, said first gland having a first sealing surface, said second gland having a second sealing surface, said first and second sealing surfaces facing said central space; wherein when said sealing surfaces are engaged with said pipe element, said first lobe surface is oriented angularly with respect to said first side surface and said second lobe surface is oriented angularly with respect to said second side surface such that said lobes will deform toward a center of said channel when said ring is seated within said channel; and connection members being positioned at opposite ends of each of said segments, said connection members being adjustably tightenable for drawing said segments toward one another and seating said ring within said channel, thereby deforming said lobes.

29. The combination according to claim 28, wherein said connection members on each of said segments comprise a pair of projections, one said projection being positioned on each of said opposite ends of said segments, said projections having holes to receive a fastener, said fastener being adjustably tightenable.

30. The combination according to claim 28, wherein said coupling comprises two of said segments.

31. The combination according to claim 28, wherein said first lobe surface has an orientation angle relative to said first side surface from 1 to 20.

32. The combination according to claim 31, wherein said orientation angle of said first lobe surface is 8.

33. The combination according to claim 31, wherein said second lobe surface has an orientation angle relative to said second side surface from 1 to 20.

34. The combination according to claim 33, wherein said orientation angle of said second lobe surface is 8.

35. The combination according to claim 28, wherein said second lobe surface has an orientation angle relative to said second side surface from 1 to 20.

36. The combination according to claim 35, wherein said orientation angle of said second lobe surface is 8.

37. The combination according to claim 28, wherein said seal is formed of a rubber material.

38. The combination according to claim 28, wherein said seal is formed of a material having low elasticity.

39. The combination according to claim 38, wherein said seal is formed of a material having an elastic limit from 0.05% to 20%.

40. The combination according to claim 38, wherein said seal is formed of a material having an elastic limit from 0.5% to 10%.

41. The combination according to claim 38, wherein said seal is formed of a material having an elastic limit from 1% to 5%.

42. The combination according to claim 38, wherein said material having low elasticity is selected from the group consisting of thermoplastic resins, thermosets, epoxies and composites including but not limited to polyethylene, polypropylene, polyamides, polyvinyl chloride, polycarbonate, polystyrene, acetals, acrylics, fluoropolymers and combinations thereof.

43. The combination according to claim 28, wherein each of said segments further comprises first and second keys positioned on opposite sides of said segments, each of said keys extending circumferentially around and projecting toward an axis extending through said central space.

44. The combination according to claim 43, wherein said first keys on each of said segments are positioned in spaced relation to said first side surfaces of said segments.

45. The combination according to claim 44, wherein said second keys on each of said segments are positioned in spaced relation to said second side surfaces of said segments.

46. The combination according to claim 43, wherein each of said keys comprises an arcuate surface facing said axis.

47. The combination according to claim 43, wherein each of said pipe elements comprises a respective circumferential groove positioned proximate to an end of each of said pipe elements, said keys engaging said grooves upon adjustable tightening of said connection members.

48. The combination according to claim 28, further comprising a first gland attached to said first lobe and a second gland attached to said second lobe, said first and second glands extending circumferentially about said ring, said first gland having a first sealing surface facing said central space, said second gland having a second sealing surface facing said central space, said sealing surfaces defining an inner diameter substantially equal to an outer diameter of said pipe elements.

49. The combination according to claim 48, further comprising: a first spring element positioned on said first gland opposite to said first sealing surface; a second spring element positioned on said second gland opposite to said second sealing surface, said spring elements extending circumferentially around said ring and biasing said first and second sealing surfaces toward said pipe elements.

50. The combination according to claim 28, further comprising a first gland attached to said first lobe and a second gland attached to said second lobe, said first and second glands extending circumferentially about said ring, said first gland having a first sealing surface facing said central space, said second gland having a second sealing surface facing said central space, said sealing surfaces defining an inner diameter greater than an outer diameter of said pipe elements when said seal is in said undeformed state.

51. The combination according to claim 50, wherein said inner diameter defined by said sealing surfaces exceeds said outer diameter of said pipe elements from 0.001 inches to 0.3 inches when said seal is in said undeformed shape.

52. The combination according to claim 50, wherein said inner diameter defined by said sealing surfaces exceeds said outer diameter of said pipe elements by 0.05 inches when said seal is in said undeformed shape.

53. The combination according to claim 50, further comprising: a first spring element positioned on said first gland opposite to said first sealing surface; a second spring element positioned on said second gland opposite to said second sealing surface, said spring elements extending circumferentially around said ring and biasing said first and second sealing surfaces toward said pipe elements.

54. A method of joining first and second pipe elements together in end to end relation, said method comprising: supporting at least first and second segments in spaced apart relation to one another on a seal comprising a ring located in a central space surrounded by said segments, said at least first and second segments being attached to one another end to end, each of said at least first and second segments having a circumferential channel, said ring being received within said circumferential channels, said ring having first and second circumferential lobes on opposite sides thereof, said first and second circumferential lobes having respective first and second lobe surfaces respectively facing first and second side surfaces defining said circumferential channel, said first lobe surface being angularly oriented with respect to said first side surface, said second lobe surface being angularly oriented with respect to said second side surface; inserting said first and second pipe elements axially into said central space and engaging said first and second pipe elements respectively with said first and second circumferential lobes on opposite sides of said ring while maintaining said first lobe surface angularly oriented with respect to said first side surface and said second lobe surface angularly oriented with respect to said second side surface; drawing said at least first and second segments toward said central space, thereby deforming said ring so as to substantially align said first lobe surface with said first side surface and to substantially align said second lobe surface with said second side surface.

55. The method according to claim 54, wherein said at least first and second segments each comprises first and second keys positioned on opposite sides of said segments, each of said keys extending circumferentially around and projecting toward said pipe elements, said method further comprising engaging said keys with said pipe elements upon said drawing said at least first and second segments toward one another.

56. The method according to claim 55, further comprising engaging said keys within circumferential grooves located in said first and second pipe elements.

57. A method of joining first and second pipe elements together in end to end relation, said method comprising: inserting said first and second pipe elements into a central space surrounded by a seal comprising a ring having first and second circumferential lobes on opposite sides thereof; surrounding said ring by at least a first and a second segment of a coupling, each of said segments having a circumferential channel, said ring being received within said circumferential channels, said first and second lobes having respective first and second lobe surfaces respectively facing first and second side surfaces defining said circumferential channel, said first lobe surface being angularly oriented with respect to said first side surface and said second lobe surface being angularly oriented with respect to said second side surface while said first and second pipe elements are engaged with said first and second circumferential lobes; drawing said at least first and second segments toward one another, thereby deforming said ring so as to substantially align said first lobe surface with said first side surface and to substantially align said second lobe surface with said second side surface.

58. The method according to claim 57, wherein said at least first and second segments each comprises first and second keys positioned on opposite sides of said segments, each of said keys extending circumferentially around and projecting toward said pipe elements, said method further comprising engaging said keys with said pipe elements upon said drawing said at least first and second segments toward one another.

59. The method according to claim 58, further comprising engaging said keys within circumferential grooves located in said first and second pipe elements.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0039] FIG. 1 is an axial end view of an example combination coupling and pipe elements according to the invention;

[0040] FIG. 2 is a longitudinal sectional view the example combination coupling and pipe elements shown in FIG. 1;

[0041] FIGS. 3 and 4 are longitudinal sectional views taken at line 3-3 of FIG. 1; and

[0042] FIGS. 5-8 are partial sectional views of additional example embodiments of a coupling according to the invention.

DETAILED DESCRIPTION

[0043] FIGS. 1 and 2 show an example combination coupling and pipe elements 10 according to the invention. Combination 10 comprises a coupling 12 having two segments 14 and 16 joined to one another end to end surrounding a central space 18. Although two segments 14 and 16 are illustrated in this example, the coupling 12 may comprise more than two segments. Each of the segments 14 and 16 has at least one connection member 20 positioned at an end. In this example embodiment, each segment 20 has two connection members 20 at opposite ends thereof. The connection members 20 connect the segments end to end and are adjustably tightenable to permit the segments 14 and 16 to be drawn toward one another and the central space 18. In this example the connection members 20 comprise projections 22 having holes 24 that accept fasteners, such as bolts 26 and nuts 28, the fasteners and the projections providing the adjustable tightenablity of the segments.

[0044] As shown in FIG. 2, each of the segments 14 and 16 comprises a circumferentially extending channel 30. Channel 30 faces the central space 18 and is defined by first and second side surfaces 32 and 34 located on opposite sides of each of the segments 14 and 16. The channel 30 is further defined by a back surface 36 extending between the side surfaces. A seal 38 is positioned within the central space 18. In this example the seal 38 comprises a ring 40 having first and second lobes 42 and 44 positioned on opposite sides of the ring. Each lobe 42 and 44 comprises a respective lobe surface 42a and 44a. First lobe surface 42a faces toward the first side surface 32 of the channel 30, and the second lobe surface 44a faces toward the second side surface 34. When the seal 38 is in an undeformed state (shown in FIGS. 1 and 2), for example, before the bolts 26 are tightened to draw the segments toward the central space 18 and compress the ring 40 against the pipe elements 46 and 48, the first lobe surface 42a is angularly oriented relatively to the first side surface 32 of channel 30, and the second lobe surface 44a is angularly oriented relatively to the second side surface 34. Orientation angles 50 between the lobe surfaces 42a and 44a and their respective side surfaces 32 and 34 may range from about 1 to about 20, 5 to about 15 and 7 to about 10. An orientation angle 50 of about 8 is expected to be advantageous.

[0045] As further shown in FIG. 2, a first gland 52 is attached to the first lobe 42 and a second gland 54 is attached to the second lobe 44 of the ring 40. First and second glands 52 and 54 extend circumferentially about the ring 40, and each gland 52 and 54 has a respective sealing surface 52a and 54a facing the central space 18. Gland sealing surfaces 52a and 54a engage the outer surfaces of pipe elements 46 and 48 and define an inner diameter 56 of the ring 40. When the ring 40 is in an undeformed state, the inner diameters 56 respectively defined between the sealing surfaces 52a and 54a of glands 52 and 54 is greater than or substantially equal to the outer diameter 58 of the pipe elements 46 and 48. This relationship between the inner diameters 56 and the outer diameters 58 of the pipe elements 46 and 48 permits the pipe elements to be inserted into ring 40 with little or no resistance, even when the ring 40 is formed of relatively stiff material having low elasticity and low resilience. As shown in FIG. 2 the ring 40 furthermore remains in its undeformed state when the pipe elements engage the lobes, 42 and 44, in this example via the sealing surfaces 52a and 54a. It is expected that it will be favorable for the inner diameters 56 defined by gland sealing surfaces 52a and 54a to exceed the outer diameters 58 of pipe elements 46 and 48 over a range from about 0.001 inches to about 0.3 inches. An inner diameter 56 exceeding the outer diameter 58 by about 0.05 inches is expected to be advantageous.

[0046] In the example combination 10 shown in FIGS. 1 and 2, each of the segments 14 and 16 of coupling 12 comprises first and second keys 60 and 62. Keys 60 and 62 are positioned on opposite sides of the segments 14 and 16 and extend circumferentially there around. Each of the keys 60 and 62 project toward an axis 64 that extends through the central space 18, in this example the axis 64 being substantially coaxial with the pipe elements 46 and 48. In this example, each key 60, 62 has an arcuate surface 66 that faces the axis 64. As shown in FIG. 2, keys 60 and 62 are in spaced relation away from the side surfaces 32 and 34 defining the channel 30, there being a respective shoulder surface 68 positioned between each key 60 and 62, and a respective side surface 32, 34. Segments 14 and 16 having keys 60 and 62 are particularly advantageous for use with pipe elements having circumferential grooves 70. The keys engage the grooves when the segments are drawn toward one another by adjustable tightening of the connection members 20 and provide positive mechanical engagement to prevent the pipe elements 46 and 48 from separating from the coupling 12 due to axial forces and/or bending on the pipe elements during use. Other types of pipe elements, such as shouldered pipe elements, shoulder and bead pipe elements, as well as plain end pipe elements may also be used with couplings and seals according to the invention.

[0047] Seals 38 may be formed from rubber materials such as nitrile and EPDM. It is further expected that seals 38 as disclosed herein will be advantageously formed of relatively stiff material having low elasticity and low resilience suitable for extreme (high and low) temperature applications. In this specification the term low elasticity means materials having an elastic limit in the range of about 0.05% to about 20%, including about 0.5% to about 10% and about 1% to about 5%. Examples of such materials include thermoplastic resins, thermosets, epoxies and composites including but not limited to polyethylene, polypropylene, polyamides, polyvinyl chloride, polycarbonate, polystyrene, acetals, acrylics and fluoropolymers as well as combinations and composites thereof. Metals, such as stainless steel, spring steel, nitinol, copper and copper berylium are also candidate materials for such seals. Because the non-metal materials listed above and useful for seals tend to creep, it may be difficult for seals formed from them to maintain a fluid tight seal. Therefore, it is advantageous that such seals have pressure actuated glands 52 and 54 as disclosed herein. Further improvement in sealing performance may be obtained using spring elements 72 positioned behind the glands 52 and 54 opposite to said gland sealing surfaces 52a and 54a. The spring elements 72 extend circumferentially around the ring 40 and bias the gland sealing surfaces 52a and 54a toward the central space 18 and into engagement with the outer surfaces of pipe elements 46 and 48. The use of spring elements 72 compensates for the tendency of the materials having low elasticity and low resilience to creep and lose seal between the gland sealing surfaces 52a and 54a and the pipe elements 46 and 48. Various types of spring elements are feasible, including, for example, coil springs, leaf springs and elastomeric bands.

[0048] An example method of joining pipe elements in end to end relation is illustrated in FIGS. 1, 3 and 4. As shown in FIGS. 1 and 3, the segments 14 and 16 are attached to one another end to end via the connection members 20 and are supported in spaced apart relation on ring 40. This configuration allows pipe elements 46 and 48 to be inserted axially into the central space 18 from opposite sides of the coupling 12 without interference from the segment 14 and 16. Note that the first and second lobe surfaces 42a and 44a are angularly oriented with respect to the channel side surfaces 32 and 34 in this configuration. Because, when ring 40 is undeformed, the diameter 56, defined by the sealing surfaces 52a and 54a of glands 52 and 54, is substantially equal to or greater than the outer diameter 58 of the pipe elements 46 and 48, the pipe elements enter the central space 18 with little resistance and engage the lobes 42 and 44 by contacting their respective glands 52 and 54. Next, the segments 14 and 16 are drawn toward the central space 18 and the pipe elements 46 and 48 by tightening bolts 26 and nuts 28. As shown in FIG. 4, the ring 40 is compressed between the segments 14 and 16 and the pipe elements 46 and 48. The ring 40 is consequently deformed such that the first lobe surface 42a substantially aligns angularly with the first side surface 32 of channel 30, and the second lobe surface 44a substantially aligns angularly with the channel's second side surface 34. The angular deformation of lobes 42 and 44 also results in the gland surfaces 52a and 54a being compressed against the outer surfaces 46a and 48a of the pipe elements 46 and 48 to effect a fluid tight seal between the glands 52 and 54 and the pipe elements 46 and 48. The spring elements 72, when present, augment the sealing force between gland sealing surfaces 52a, 54a and the pipe elements 46 and 48 and help prevent creep of the material comprising the ring 40 from compromising the integrity of the seal. In the example shown, keys 60 and 62 on the segments 14 and 16 engage circumferential grooves 70 in the pipe elements 46 and 48.

[0049] In another example method for joining pipe elements in end to end relation, pipe elements 46 and 48 are first inserted axially into the central space 18 surrounded by ring 40. Due to the dimensional relationship between gland diameters 56 and pipe element diameters 58 (i.e., gland diameter 56 being as large as or larger than pipe element diameter 58 when ring 40 is undeformed), the pipes enter the central space 18 with little resistance. Next the segments 14 and 16 are assembled surrounding ring 40 and attached to one another end to end using bolts 26 and nuts 28 (see FIG. 1). Ring 40 is received within the channel 30, the first and second lobe surfaces 42a and 44a being angularly oriented with respect to the channel side surfaces 32 and 34. Next, the segments 14 and 16 are drawn toward the central space 18 and the pipe elements 46 and 48 by tightening bolts 26 and nuts 28. As shown in FIG. 4, the ring 40 is compressed between the segments 14 and 16 and the pipe elements 46 and 48. The ring 40 is consequently deformed such that the first lobe surface 42a substantially aligns angularly with the first side surface 32 of channel 30, and the second lobe surface 44a substantially aligns angularly with the channel's second side surface 34.

[0050] The angular deformation of lobes 42 and 44 also results in the gland surfaces 52a and 54a being compressed against the outer surfaces 46a and 48a of the pipe elements 46 and 48, reducing or eliminating the amount of radial compression applied by the back wall of the channel to the ring necessary to effect a fluid tight seal between the glands 52 and 54 and the pipe elements 46 and 48. The spring elements 72, when present, augment the sealing force between gland sealing surfaces 52a, 54a and the pipe elements 46 and 48 and help prevent creep of the material comprising the ring 40 from compromising the integrity of the seal. In the example shown, keys 60 and 62 on the segments 14 and 16 engage circumferential grooves 70 in the pipe elements 46 and 48.

[0051] Deformation of the ring 40 is ensured because the segments 14 and 16 are significantly stiffer than the ring, the segments typically being formed of ductile iron or steel.

[0052] FIGS. 5-8 show additional example embodiments of the coupling according to the invention. A general characteristic linking all of the embodiments disclosed herein concerns the width of the seal relative to the width of the channel. When the seal is in an undeformed state, at least a portion of the first and second lobe surfaces are in contact with the side surfaces such that the lobes deform toward a center of the channel when the seal is seated within the channel.

[0053] As shown in FIG. 5, segment 74 comprises channel 76 defined by oppositely disposed side surfaces 78 and 80 and a back surface 82. Seal 84 comprises lobes 86 and 88. Each lobe has a respective lobe surface 86a and 88a facing a respective side surface 78 and 80. In this example, lobe surfaces 86a and 88a are convexly curved and project outwardly away from one another so that at least a portion of the lobe surfaces 86a and 88a has a width 90 wider than a distance 92 (in this example the widest distance) between side surfaces 78 and 80. The difference in the widths 90 and 92 causes contact between lobe surfaces 86a and 88a and respective side surfaces 78 and 80 as the seal 84 is seated within the channel 76. This causes the lobes 86 and 88 to deform inwardly toward the center 76a of channel 76. FIG. 6 shows a design wherein the lobes 86 and 88 are displaced toward the central space 18 by respective extension portions 93 and 95.

[0054] As shown in FIG. 7, segment 94 comprises channel 96 defined by oppositely disposed side surfaces 98 and 100 and a back surface 102. Seal 104 comprises lobes 106 and 108. Each lobe has a respective lobe surface 106a and 108a facing a respective side surface 98 and 100. In this example, side surfaces 98 and 100 are convexly curved and project inwardly toward one another so that at least a portion of the lobe surfaces 106a and 108a has a width 112 wider than a distance 110 between side surfaces 98 and 100. The difference in the widths 110 and 112 causes contact between lobe surfaces 106a and 108a and respective side surfaces 98 and 100 as the seal 104 is seated within the channel 96. This causes the lobes 106 and 108 to deform inwardly toward the center 96a of channel 96.

[0055] As shown in FIG. 8, segment 114 comprises channel 116 defined by oppositely disposed side surfaces 118 and 120 and a back surface 122. Seal 124 comprises lobes 126 and 128. Each lobe has a respective lobe surface 126a and 128a facing a respective side surface 118 and 120. In this example, side surfaces 118 and 120 are convexly curved and project inwardly toward one another and lobe surfaces 126a and 128a are convexly curved and face outwardly away from one another so that at least a portion of the lobe surfaces 126a and 128a has a width 130 wider than a distance 132 between side surfaces 118 and 120. The difference in the widths 130 and 132 causes contact between lobe surfaces 126a and 128a and respective side surfaces 118 and 120 as the seal 124 is seated within the channel 116. This causes the lobes 126 and 128 to deform inwardly toward the center 116a of channel 116.

[0056] Having the width of the lobe surfaces wider than the widest distance between the side surfaces defining the channel of the segment provides the caroming action that deforms the lobes inwardly toward one another so as to effect a fluid tight seal when the segments are drawn toward one another and toward the pipe elements. This caroming action is expected to be particularly effective when used in conjunction with seals formed of materials having low elasticity and low resilience.