COUPLING THAT HAS A RETAINER WITH TABS.

Abstract

A plain-end pipe coupling is formed from segments joined end-to-end around a central space; the ends are connected end-to-end by lugs on each segment with fasteners extending between them; each segment has channels on opposite sides facing the central space with floors at different radii; retainers are received within the channels; the retainers have teeth and one or more offset tabs that cooperate with the channels to prevent improper assembly; an annular seal is received within a channel positioned on each segment between the retainer channels.

Description

This application is based on and claims priority over U.S. Provisional Application No. 62 / 336,885, filed on May 16, 2016, and incorporated herein by reference. FIELD OF INVENTION This invention relates to pipe couplings for joining plain-ended pipe elements. BACKGROUND OF THE INVENTION Mechanical couplings for joining plain-ended pipe elements end-to-end comprise interlocking segments that can be circumferentially placed around the end portions of coaxially aligned pipe elements. The term "pipe element" is used herein to describe any pipe-like article or component that has a pipe-like shape. Pipe elements include pipe materials, pipe fittings such as elbows, caps, and tees, as well as fluid control components such as valves, reducers, filters, chokes, pressure regulators, and the like. Each mechanical coupling segment comprises a housing with inwardly projecting lugs. Toothed retainers can be used to form these projections for couplings to plain-end pipe fittings. When the retainers are properly oriented on the segments, the engagement between the teeth and the pipe fittings provides mechanical restraint to the joint and ensures that the pipe fittings remain coupled even under high internal pressure and / or external forces. The housings also define an annular channel or box that receives a ring gasket or seal, typically an elastomeric ring that couples the ends of each pipe fitting and cooperates with the segments and pipe fittings to provide a fluid-tight seal. The segments have connecting members, typically in the form of lugs, that project outward from the housings.The lugs are adapted to receive fasteners, such as nuts and bolts, which can be adjusted to attract the segments to each other. Some retainers use teeth that are oriented at an angle to a line extending radially from an axis coaxial with the center space. The proper angle allows the teeth to be self-acting; that is, the mechanical engagement of the pipe fittings and teeth increases with increasing force on the pipe fittings attempting to pull or push them out of the engagement. Therefore, the force resisting pullout increases with the applied force that might otherwise cause pullout. However, if such retainers are oriented improperly—for example, if the retainer is inverted within the engagement—then the teeth will not be self-acting against forces that might pull or push the pipe fitting out of the engagement.Thus, the retainer might not provide sufficient mechanical engagement against removal, and the pipe fittings are not securely held within the coupling. For couplings with retainers, it is difficult to determine if the retainers are properly oriented once the coupling has been installed. It would be advantageous if pipe couplings could be designed to alert the user if the retainer is not properly oriented during assembly. BRIEF DESCRIPTION OF THE INVENTION The invention relates to a coupling for joining pipe elements. In one exemplary embodiment, the coupling comprises a plurality of segments joined end-to-end surrounding a central space for receiving the pipe elements. For example, there may be no more than a first and a second segment. Each segment comprises first and second channels positioned on opposite sides of the segment. Each channel extends between the ends of the segments and has a first and a second deck facing the central space. The first deck has a larger radius of curvature than the second deck. First and second retainers are positioned in the first and second channels, respectively. Each retainer comprises a band having opposite ends. A plurality of teeth are positioned along one edge of the band and project into the central space.At least one tab is placed along an opposite edge of the band. The band overlaps the first layer, and the tab lies on the second layer when the retainers are placed within the canals. A plurality of tabs is advantageous. The coupling example also includes a third channel placed within each of the segments. The third channels face the central space. A seal is placed. IVIA / S / ZUZZ / UII 1 ring within the third channels. The annular seal has an inner surface sized to receive the pipe elements and may have an outer surface sized to support the segments in a sufficiently separate relationship to allow the insertion of the pipe elements into the central space while the segments are joined together. As a further example, retaining bands may be sized to cooperate with the annular seals to support the housing portions in a separate relationship. In one particular exemplary arrangement, the third canals are positioned between the first and second canals, or adjacent to the first canal if the second canal is absent. As a further example, the teeth are oriented angularly with respect to a line extending radially from an axis coaxial with the central space. Additionally, as an example, the tab or tabs are oriented perpendicularly to a line extending radially from an axis coaxial with the central space. In a specific instance, the tab or tabs project into the third canals. Another exemplary coupling mode further comprises a first opening in at least one of the segments. The first opening provides a line of sight to the central space and may be aligned with the first channel. In one specific exemplary mode, the first opening is positioned between two of the segments. The opening may include a channel at the interface between the segments. Additionally, by way of example, a second opening is positioned in at least one of the segments. The second opening provides a line of sight to the central space and may be aligned with the second channel. In one specific example, the second opening is positioned between two of the segments. The second opening may include a channel at the interface between the segments. Another exemplary embodiment comprises the first and second connecting members positioned at opposite ends of the segments. At least one of the connecting members can be adjusted to pull the first and second segments apart. In one exemplary embodiment, the first connecting member comprises the first and second lugs positioned respectively on the first and second segments. The first and second lugs are separated in a facing relationship. A first fastener extends between the first and second lugs. Tightening the first fastener pulls the segments apart. In another exemplary embodiment, the second connecting member comprises the third and fourth lugs positioned respectively on the first and second segments. The third and fourth lugs are facing each other. A second fastener extends between the third and fourth lugs.Tightening the second fastener pulls the segments apart. The invention further comprises a coupling for joining pipe elements, which, by way of example, comprise a plurality of segments (for example, no more than a first and a second segment) joined end-to-end, surrounding a central space for receiving the pipe elements. In this exemplary embodiment, each segment comprises at least one channel positioned on one side of the segment. At least one channel extends between the ends of the segments and has a first and a second deck facing the central space. The first deck has a larger radius of curvature than the second deck. A retainer is positioned in at least one channel. The retainer comprises a band having opposite ends. A plurality of teeth is positioned along one edge of the band and projects into the central space. At least one tab is positioned along an opposite edge of the band.The band overlaps the first layer, and the tab overlaps the second layer when the retainer is placed within at least one canal. A plurality of tabs is advantageous. The invention further includes a method for joining pipe elements. In one exemplary embodiment, the method comprises: insert at least one first pipe element within a central space defined by a plurality of segments connected end-to-end, spaced far enough apart to allow insertion of the pipe elements; and observe, through a first opening in at least one of the segments, whether or not the first pipe element is present within the central space. The exemplary method may also include: insert at least a second pipe element into the central space; and observe, through a second opening in at least one of the segments, whether or not the second pipe element is present within the central space; Additionally, by way of example, the method of conformity with the invention may also comprise: Adjust the positions of the pipe elements within the central space if the pipe elements are not present within the central space; and pull the segments into the central space and into coupling with the pipe elements once it is observed that the pipe elements are present within the central space. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is an isometric view of an exemplary embodiment of a coupling according to the invention; Figure 1A is a partial isometric view of the coupling shown in Figure 1 rotated 90° around line 3-3; Figure 2 is an axial view of the exemplary coupling shown in Figure 1; Figure 3 is a cross-sectional view taken at line 3-3 of Figure 1; Figure 4 is a partial cross-sectional view of a portion of the exemplary coupling shown in Figure 1; Figure 5 is an isometric view of an exemplary retainer used with the coupling example in Figure 1; Figure 6 is a partial cross-sectional view of a portion of the exemplary coupling shown in Figure 1; Figure 7 is an isometric view illustrating the assembly of a pipe connection using a coupling as shown in Figure 1; and Figure 8 is a cross-sectional view illustrating the assembly of a pipe connection using a coupling as shown in Figure 1. DETAILED DESCRIPTION OF THE INVENTION Figures 1 and 2 show an exemplary coupling 10 according to the invention. The coupling 10 comprises a plurality of segments, in this exemplary embodiment, the first and second segments 12 and 14, joined end-to-end, surrounding a central space 16. The connection of segments 12 and 14 is effected by means of the first and second connecting members 18 and 20 placed at the respective opposite ends 22 and 24 of segments 12 and 14. In this exemplary embodiment, the first connecting member 18 comprises the first and second lugs 26 and 28, and a fastener 30 comprising a bolt 32 and a nut 34 (see Figure 2). Lugs 26 and 28 are oriented in relation to each other and extend from the ends 22 of the respective segments 12 and 14. The lugs have holes 36 which receive a first fastener 30, the fastener extending between the first and second lugs.Comprising lugs 26, 28, and a fastener 30, the first connecting member has the ability to be adjusted to pull segments 12 and 14 together to join the pipe elements as described below. Furthermore, in this exemplary embodiment, the second connecting member 20 comprises the third and fourth lugs 27 and 29, and a second fastener 31 comprising a bolt 33 and a nut 35. The lugs 27 and 29 are oriented relative to each other and extend from the ends 24 of the respective segments 12 and 14. The lugs have holes 36 which receive a second fastener 31, the fastener extending between the third and fourth lugs. Comprising lugs 27, 29 and fastener 31, the second connecting member also has the ability to be tightened in an adjustable manner to pull segments 12 and 14 together to join the pipe elements as described below. As shown in the cross-section in Figure 3, each segment 12 and 14 comprises the first and second channels 54 and 56, respectively, positioned on opposite sides 58 and 60 of each segment. The first and second channels 54 and 56 extend between the ends 22 and 24 of segments 12 and 14 (see Figure 1) and face the central space 16. As shown in detail in Figure 4, each channel 54, 56 (channel 56 in segment 14 is shown) is defined by side walls 62 and 64 positioned in a spaced relationship to each other. Each channel 54, 56 also has the first and second floors 66 and 68 situated between the side walls 62 and 64. Floors 66 and 68 face the central space 16 and have an arched shape as they extend between the ends 22 and 24 of segments 12 and 14.As shown in Figure 4, the first floor 66 is positioned closer to side 60 of segment 14 and has a radius of curvature 70 greater than the second floor 68, which has a radius of curvature 72. As shown in Figure 3, channels 54 and 56 and the arrangement of their floors 66 and 68 are symmetric about axis 74 that extends transversely through coupling 10. As further shown in Figures 3 and 4, channels 54 and 56 each receive a respective retainer 76. The retainer 76 is shown in detail in Figure 5 and comprises an arched band 78 having oppositely arranged ends 80 and 82. The band 78 thus forms a split ring which, when radially compressed, will deform to a smaller radius of curvature (see Figure 8). In some embodiments, each band 78 is sized such that the contact between the bands 78 and the respective segments 12 and 14 within channels 54 and 56 allows one or both bands 78 to support segments 12 and 14 in separate relationships, as shown in Figure 1. A plurality of teeth 84 is positioned along an edge 86 of the band 78. The teeth 84 project from the band 78 into the central space 16.As shown in Figures 3 and 4, the teeth 84 are oriented angularly toward the axis 74 with respect to a line 88 extending radially from an axis 40 arranged coaxially with the center space 16. The angular orientation is advantageous for retaining pipe elements as described below. As shown in Figure 5, in this example, a plurality of tabs 90 are positioned along an edge 92 arranged opposite edge 86. As shown in Figure 4, the tabs 90 are oriented substantially perpendicular to line 88 and are offset from band 78 toward axis 40 arranged coaxially with the center space 16. This offset of the tabs 90 allows them to overlap the second floor 68, and band 78 to overlap the first floor 66, when the retainers 76 are appropriately oriented within respective channels 54 and 56 as shown in Figures 3 and 4. The appropriate mounting of the retainers 76 within channels 54 and 56 allows the pipe elements to be inserted into a pre-assembled coupling 10 as described below.However, as shown in Figure 6, channels 54 and 56 (shown as 56) and retainers 76 are sized such that if coupling 10 is improperly assembled with band 78 overlapping the second floor 68 and tabs 90 overlapping the first floor 66, a pipe element is prevented from being inserted into the coupling, also described below. As shown in Figure 3, segments 12 and 14 further comprise a third channel 94. Channel 94 is positioned between the first and second channels 54 and 65 (or adjacent to the first channel if the second channel is not present) and is oriented toward the center space 16. Channel 94 receives an annular seal 96 that ensures a fluid-tight seal. The annular seal 96 is made of a flexible, elastic material such as EPDM or other rubber compounds and has internal surfaces 98 sized to receive pipe elements when inserted into the center space 16 as described below. A pipe stop 100 is positioned between the internal surfaces 98. The pipe stop projects into the center space 16 and limits the insertion of the pipe elements by coupling them to the desired depth when inserted into the coupling 10.The annular seal 96 also has an outer surface 102 that is sized to engage and support segments 12 and 14 in a separate relationship, as shown in Figures 1 and 3. One or more of the bands 78 may also cooperate with the annular seal 94 to support segments 12 and 14 in a separate relationship. The separation of segments 12 and 14, when supported by the annular seal 96 and / or band or bands 78, is sufficient to allow the pipe elements to be inserted into the coupling when it is in its pre-assembled state (Figures 1, 2, and 3). Figure 3 shows an exemplary channel configuration where the second decks 68 are positioned between the first decks 66 and the third channel 94. In this example, the tabs 90 project into the third channel 94 when the retainers 76 are appropriately oriented within the coupling 10. As shown in Figure 1, the coupling 10 further comprises a first opening 42 in segment 12. In this example, the opening 42 is aligned with the first channel 54 and provides a line of sight 44 into the center space 16. In this exemplary embodiment, the opening 42 is positioned at the interface 46 between segments 12 and 14 and is formed as a channel 48 in both segments 12 and 14. The channels 48 in each of segments 12 and 14 are aligned so that when the segments are pulled into the coupling (Figure 8), they provide a view into the center space 16 to allow visual confirmation that a pipe element is present and seated at least past the retainer. As shown in Figure 1A, a second opening 50 is also positioned in at least one of segments 12 and 14.The second opening 50 is also aligned with the second channel 56 in this exemplary mode (see Figure 3) and also provides a line of sight to the central space 16. Again, in the illustrated exemplary mode 10, the second opening 50 is positioned between segments 12 and 14. The opening 50 is also formed by channels 48 at the interface 46 between segments 12 and 14. The second opening also allows visual confirmation that a pipe element is present within the central space 16. As shown in Figures 1, 1A, and 3, each segment 12 and 14 also comprises a first and a second arched surface 63 and 65, respectively, positioned on the side walls 62 and 64. The arched surfaces 63 and 65 face the central space 16, and a plurality of projections 67 can be positioned on each arched surface 63, 65. The projections 67 are spaced relative to each other along the arched surfaces 63 and 65 and project into the central space 16. The projections 67, when clamped in coupling with the external surface of the pipe element, increase the joint stiffness and accommodate a wider tolerance range in the outside diameter of the pipe, as described below. The operation of the exemplary coupling 10 is illustrated in Figures 7 and 8. As shown in Figure 7, the coupling 10 is provided in the pre-assembled state, with segments 12 and 14 connected end-to-end using connecting member 18 (comprising tabs 26 and 28 and fastener 30) and connecting member 20 (comprising tabs 27, 29, and fastener 31). Segments 12 and 14 are held in a sufficiently separate relationship to permit the insertion of pipe elements 104 and 106 into the center space 16 by means of the O-ring 96, the retainers 76, or a combination of the retainers 76 and the O-ring 96.With reference to Figure 4, when pipe element 106 is inserted into the center space 16, the retainer 76, which is properly oriented with band 78 overlapping the first floor 66 and tabs 90 overlapping the second floor 68, has a radius of curvature that allows the pipe element to clear tooth 84, which projects into the center space 16 when the coupling 10 is in the pre-assembled state. However, if, as shown in Figure 6, the retainer 76 is improperly oriented, with band 78 overlapping the second floor 68, the retainer's radius of curvature is smaller, and teeth 84 effectively prevent the insertion of the pipe element into the center space 16 with segments 12 and 14 in their spaced relationship in the pre-assembled state.This cooperation between the retainer 76, its tabs 90, the teeth 84, and the first and second floors 66 and 68 of the channels 54 and 56 prevents the incorrect assembly of a pipe joint using the coupling 10. If the pipe elements 104 and. If the retainer 106 could be inserted with the retaining teeth 84 oriented in the wrong direction (Figure 6), then the teeth will not automatically engage against forces that would pull or push the pipe element out of the coupling. Therefore, the retainer would provide reduced mechanical restraint. Once both pipe elements 104 and 106 are inserted into the center space coupling, the pipe stop 100 and the respective internal surfaces of the annular seal 96 (Figure 8) are engaged by fasteners 30 and 31 (see Figure 1). Tightening fasteners 30 and 31 pulls segments 12 and 14 apart, and, as shown in Figure 8, the segments compress the annular seal 96 and retainers 76 against the pipe elements 104 and 106. The compression of the annular seal 96 forms a fluid-tight seal, and the compression of the retainer 76 forces the teeth 84 into mechanical engagement with the outer surfaces of the pipe elements 104 and 106 to form a secure seal. The advantage of the angular orientation of the teeth 84 is readily apparent, as this causes the teeth to self-drive and resist axial forces which could pull or push the pipe elements out of coupling with the coupling 10.As shown in Figure 7, openings 42 and 50 (42 is shown), aligned with channels 54 and 56, allow a line of sight 44 into the central space 16, which allows confirmation that pipe elements 104 and 106 are coupled by teeth 84 of retainer 76. Projections 67 are also forced into the coupling with pipe elements 104 and 106 when segments 12 and 14 are pulled against each other. Projections 67 add rigidity to the joint between coupling 10 and pipe elements 104 and 106 under their engagement with the outer surfaces of the pipe elements. Furthermore, projections 67 allow coupling 10 to accommodate a larger outside pipe diameter tolerance in combination with the known manufacturing tolerances for coupling 10. When the outside diameter of pipe elements 104 and 106 is near the small end of the tolerance range, the presence of projections 67 ensures a mechanical fit between coupling 10 and pipe elements 104 and 106.However, when the pipe diameter is at the large end of the tolerance range, the projections will tend to deform the outer surface of the pipe fittings locally, and the projections 67 may also deform. For couplings 10 used with plain-end pipe fittings, this is particularly advantageous since plain-end couplings are typically designed so that the arched surfaces 63, 65 (see Figure 3) do not engage the outer surfaces of the pipe fittings. This arrangement ensures that the clamping force provided by the fasteners 30 and 31 (see Figure 2) is fully applied to the retainers 76.If the arched surfaces 63, 65 of coupling 10 were to engage directly with the outer surface of the pipe, the clamping force would be divided between the contact of the arched surfaces with the pipe and the contact between the retainers 76 and the pipe elements. Because the surface areas of the projections 67 are small compared to the arched surfaces 63, 65 and contact the outer surface of the pipe element only at discrete points, only the minimum clamping force of the fasteners 31 and 31 is required to be diverted to the contact between the projections 67 and the pipe elements 104 and 106 to provide improved rigidity without compromising the axial retention provided by the retainers 76. The operation of exemplary coupling 10 can be viewed as illustrative of a method for connecting pipe elements comprising inserting a first pipe element (106) into a central space (16) defined by a plurality of segments (12, 14) connected end-to-end with sufficient separation to permit the insertion of the pipe elements (Figure 7, showing coupling 10 in the previously assembled state). Then, observing, through a first opening (50) in at least one of the segments, whether or not the first pipe element is present within the central space. A further step of the method comprises inserting at least a second pipe element (104) into the central space and then observing, through a second opening (42) in at least one of the segments, whether or not the second pipe element is present within the central space.The method may also comprise adjusting the positions of the pipe elements within the central space if the pipe elements are not present within the central space, and then pulling the segments into the central space and into coupling with the pipe elements, as shown in Figure 8, once it is observed that the pipe elements are present within the central space.

Claims

1. - A coupling (10) for joining pipe elements, said coupling comprising: a plurality of segments (12, 14) joined end to end (22, 24) surrounding a central space (16) for receiving the pipe elements, each of the segments comprising: first and second channels (54, 56) positioned on opposite sides of the segments, each of the channels extending between the ends of the segments and having a first floor (66) and a second floor (68) oriented towards the central space, the first floor having a radius (70) of curvature greater than the (72) second floor;first and second retainers (76) positioned respectively in the first and second canals (54, 56), each retainer comprising a band (78) having oppositely disposed ends, a plurality of teeth (84) being positioned along an edge (86) of the band (78) and projecting into the central space (16), at least one tab (90) being positioned along an opposite edge (92) of the band, the band overlapping the first floor, the at least one tab overlapping the second floor when the retainers are positioned within the canals.; 2 - The coupling according to claim 1, further characterized in that it additionally comprises: a plurality of tabs (90); or a third channel (94) positioned between the first and second channels in each of the segments, the third channels extending between the ends (24, 26) of the segments and oriented towards the central space (16).

3. The coupling according to claim 1, further characterized in that the teeth (84) are oriented angularly with respect to a line (88) extending radially from an axis (40) arranged coaxially with the central space.

4. The coupling according to claim 1, further characterized in that at least one tab is oriented perpendicular to a line (88) extending radially from an axis (40) arranged coaxially with the central space.

5. The coupling according to claim 1, further characterized in that the at least one tab (90) is displaced from the band towards an axis (40) arranged coaxially with the central space (16); preferably the at least one tab projects towards the third channel (94).

6. The coupling according to claim 1, further characterized in that it comprises no more than a first and a second segment joined end-to-end surrounding the central space; preferably further comprising first and second connecting members (18, 20) positioned at opposite ends of the first and second segments, at least one of the connecting members being adjustablely tightened to pull the first and second segments towards each other; more preferably the first connecting member comprises: first and second lugs (26, 28) positioned respectively on the first and second segments, the first and second lugs being oriented relative to each other; a first fastener (30) extending between the first and second lugs, tightening of the first fastener pulling the segments towards each other;More preferably, the second connecting member comprises: third and fourth lugs (27, 29) positioned respectively on the first and second segments, the third and fourth lugs being oriented relative to each other; a second fastener extending between the third and fourth lugs (27, 29), tightening the second fastener by pulling the segments towards each other.

7. The coupling according to claim 1, further characterized in that it additionally comprises a first opening (42) in at least one of the segments, the first opening providing a line of sight to the central space.

8. The coupling according to claim 7, further characterized in that the first opening (42) is aligned with the first channel (54).

9. The coupling according to claim 7, further characterized in that the first opening is positioned between two of the segments; the first opening comprises a channel (48) positioned at an interface between the two segments.

10. The coupling according to claim 7, further characterized in that it additionally comprises a second opening (50) in at least one of the segments, the second opening providing a line of sight to the central space; preferably the second opening is aligned with the second channel. 11.- The coupling according to claim 7, further characterized in that it additionally comprises a second opening (50) in at least one of the segments, the second opening (50) providing a line of sight to the central space, wherein the second opening is positioned between two of the segments (12, 14); preferably the second opening comprises a channel (48) positioned at an interface between the two segments (12, 14). 12.- The coupling according to claim 1, further characterized in that it additionally comprises: an annular seal (96) positioned within the third channels, the annular seal having an inner surface (96) dimensioned to receive the pipe elements and an outer surface (102) dimensioned to support the segments in a sufficiently spaced relationship to permit insertion of the pipe elements into the central space while the segments are joined to one another; preferably the retaining bands are dimensioned to cooperate with the annular seal to support the segments in the spaced relationship.

13. A method for joining pipe elements, said method comprising: 5 providing a coupling for joining pipe elements according to claim 1; inserting at least a first pipe element into the central space defined by the plurality of segments joined end-to-end in a sufficiently spaced relationship to permit insertion of the pipe elements; observing, through a first opening in at least one of the segments, whether or not the first pipe element is present within the central space. 10 14. The method according to claim 13, further characterized in that it additionally comprises: inserting at least a second pipe element within the central space; observing, through a second opening in at least one of the segments, whether or not the second pipe element is present within the central space.

15. The method according to claim 14, further characterized 15 in that it further comprises: adjusting the positions of the pipe elements within the central space if the pipe elements are not present within the central space; and pulling the segments into the central space and into coupling with the pipe elements once it is observed that the pipe elements are present within the central space.

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