PIPE COUPLING HAVING COMPRESSION BAND
Field of the Invention This invention concerns couplings for joining pipe elements end to end, the couplings having multiple segments held together by a compression band.
Background of the Invention Mechanical couplings for joining pipe elements together end-to-end comprise interconnectable segments that are positionable circumferentially surrounding the end portions of co-axially aligned pipe elements. The term "pipe element" is used herein to describe any pipe-like item or component having a pipe like form. Pipe elements include pipe stock, pipe fittings such as elbows, caps and tees as well as fluid control components such as valves, reducers, strainers, restrictors, pressure regulators and the like.
Each mechanical coupling segment comprises a housing having arcuate surfaces which project radially inwardly from the housing and engage plain end pipe elements or circumferential grooves that extend around each of the pipe elements to be joined. Engagement between the arcuate surfaces and the pipe elements provides mechanical restraint to the joint and ensures that the pipe elements remain coupled even under high internal pressure and external forces. The housings define an annular channel that receives a gasket or seal, typically an elastomeric ring which engages the ends of each pipe element and cooperates with the segments to provide a fluid tight seal. The segments have connection members, typically in the form of lugs which project outwardly from the housings. The lugs are adapted to receive fasteners, such as nuts and bolts, which are adjustably tightenable to draw the segments toward one another. To ensure a good fit between the couplings and the pipe elements, the arcuate surfaces on prior art couplings have a radius of curvature that is substantially matched to the radius of curvature of the outer surface of the pipe element that it is intended to engage. For couplings used with grooved pipe elements, the radii of curvature of the arcuate surfaces are smaller than the radii of curvature of the outer surfaces of the pipe elements outside of the grooves so that the arcuate surfaces fit within and engage the grooves properly.
This geometrical relation between the arcuate surfaces of the couplings and the outer surfaces of the pipe elements in prior art couplings results in a tedious and time consuming installation process when mechanical couplings are used. Typically, the coupling is received by the technician with the segments bolted together and the ring seal captured within the segments' channels. The technician first disassembles the coupling by unbolting it, removes the ring seal, lubricates it (if not pre-lubricated) and places it around the ends of the pipe elements to be joined. Installation of the ring seal requires that it be lubricated and stretched to accommodate the pipe elements, an often difficult and messy task, as the ring seal is usually stiff and the lubrication makes manual manipulation of the seal difficult. With the ring seal in place on both pipe elements, the segments are then placed one at a time straddling the ends of the pipe elements and capturing the ring seal against them. During placement, the segments engage the seal, the arcuate surfaces are aligned with the grooves when present, or with alignment marks made on the outside surfaces of the pipe elements, the bolts are inserted through the lugs, the nuts are threaded onto the bolts and tightened, drawing the coupling segments toward one another, compressing the seal and engaging the arcuate surface within the grooves .
As evident from the previous description, installation of mechanical pipe couplings according to the prior art requires that the technician typically handle at least seven individual piece parts (and more when the coupling has more than two segments) , and must totally disassemble and reassemble the coupling. Significant time, effort and expense would be saved if the technician could install a mechanical pipe coupling without first totally disassembling it and then reassembling it, piece by piece.
Summary of the Invention The invention concerns a pipe coupling positionable straddling facing end portions of a pair of pipe elements for securing the pipe elements together in end to end relationship. The pipe coupling comprises a deformable sealing member having an inner diameter sized to receive the pipe elements and an outer surface. A plurality of segments are supported on the outer surface of the sealing member. The segments are positioned circumferentially around the sealing member in predetermined spaced apart relation to one another. Each segment has a pair of arcuate surfaces positioned on opposite sides of the sealing member. The arcuate surfaces are engageable with the pipe elements to retain them in end to end relationship. A compression band extends around an outer perimeter of the segments. The segments are captured between the band and the sealing member. A tensioning member is mounted on the band. The tensioning member is adjustably tightenable for forcing the segments substantially radially inwardly against the sealing member. Tightening of the tensioning member moves the arcuate surfaces into engagement with the pipe elements.
Preferably, the segments are spaced apart from one another at substantially equal intervals. In order to maintain the spacing of the segments, one or more projections are mounted on either the band or the segments. The projections limit relative motion between the band and the segments and serve to hold the segments at a predetermined position relatively to the band. Preferably, the projections are attached to the segments and extend substantially radially outwardly. The band has apertures therethrough or indentations at spaced intervals for receiving the projections.
The segments have oppositely disposed end faces that engage each other as the tensioning member is tightened to force the segments inwardly against the sealing member. In one embodiment, the end faces are oriented substantially parallel to a longitudinal axis of the pipe elements. The end faces may be brought into engagement with one another upon tightening of the tensioning member.
In another embodiment, the segments have oppositely disposed end faces oriented angularly relatively to a longitudinal axis of the pipe elements. Each end face on each segment is substantially parallel to an adjacent end face on an adjacent segment. The end faces on each segment have opposite slopes from one another. The end faces are brought into engagement with one another upon tightening of the tensioning member, and the angular orientation of the end faces causes neighboring segments to move in opposite directions lengthwise along the pipe elements.
In yet another embodiment, the segments have oppositely disposed end faces oriented angularly relatively to a longitudinal axis of the pipe elements. Each end face on each segment is substantially parallel to an adjacent end face on an adjacent segment. The end faces on each segment have substantially the same slope. The end faces are brought into engagement with one another upon tightening of the tensioning member, and the angular orientation of the end faces causes neighboring segments to rotate in opposite directions relative to one another about respective axes along radii of the segments that are substantially perpendicular to the axis of the pipe elements.
Brief Description of the Drawings Figure 1 is an axial cross-sectional view of a coupling according to the invention;
Figure IA is an axial cross-sectional view of an alternate embodiment of a coupling according to the invention;
Figures 2, 2A and 2B are longitudinal sectional views of the coupling shown in Figure 1;
Figures 3 and 3A are side views of a coupling embodiment according to the invention;
Figure 4 is a partial axial cross-sectional view showing a detail of a coupling according to the invention;
Figure 5 is a partial axial cross-sectional view showing a detail of a coupling according to the invention;
Figure 6 is a perspective view showing a detail of a coupling according to the invention;
Figure 7 is an axial view of a segment used with the coupling shown in Figure 3;
Figure 7A is a side view of the segment shown in Figure 7;
Figures 8 and 8A are side views of a coupling embodiment according to the invention; Figure 9 is an axial view of a segment used with the coupling shown in Figure 8; and
Figure 9A is a side view, of the segment shown in Figure 9.
Detailed Description of the Embodiments Figure 1 shows a compression band pipe coupling 10 for securing pipe elements together in end to end relationship according to the invention. Coupling 10 comprises a deformable sealing member 12, preferably in the form of a ring of elastomeric material. Sealing member 12 engages the pipe elements to ensure a fluid-tight joint as described below. Sealing member 12 has an inner diameter 14 sized to receive the pipe elements and an outer surface 16. Outer surface 16 supports a plurality of • segments 18. Segments 18 are preferably formed of metal and may be cast, formed, stamped or machined. The segments are supported on the outer surface 16 of the sealing member 12 and are positioned circumferentially around it in predetermined spaced apart relation to one another. A compression band 20 extends around the outer perimeter of the segments 18. Band 20 is preferably a flexible metal strap and has opposite ends 22 and 24 connected to one another by a tensioning member 26 mounted thereon. Tensioning member 26 preferably comprises a threaded bolt 28 mounted on one band end 22 and a threaded body 30 mounted on the other band end 24. The bolt 28 is rotatable and engages the threaded body 30. Tightening of the bolt draws the band ends 22 and 24 towards one another, applies tension to the band and forces the segments 18 radially inwardly against the sealing member 12.
Figure IA illustrates an alternate coupling embodiment 11 wherein compression band 2.0 is divided into a plurality of band portions, in this example, two portions, 20a and 20b. Each band portion has opposite ends 22a and 24a, and 22b and 24b respectively, which are positioned adjacent to one another so as to arrange the band portions in end to end relationship around the segments 18. The ends in facing relation, 22a and 24b, and 22b and 24a, are joined by- respective tensioning members 26a (mounted between 22a and 24b) and 26b (mounted between 22b and 24a) . Each tensioning member preferably also comprises a bolt 28, mounted on one end of a band portion (22a and 22b) , the bolt engaging a threaded body 30 mounted on the adjacent end portion (24a, 24b) . Tightening of the tensioning members applies tension to the band portions and forces the segments 18 radially inwardly against the sealing member 12. Compression band couplings having two or more band portions and the appropriate number of tensioning members are advantageous for use with larger diameter pipes to distribute the tension force among multiple tension members and limit the size of the bolts required to reasonable and practical lengths and diameters.
With reference again to Figure 1, it is advantageous to maintain the segments 18 in spaced apart relation at substantially equal intervals around the seal. This ensures that no large gaps form between the segments that will allow the sealing member to be pinched during assembly or blow out under pressure. To this end, each segment 18 has a projection 32 that extends radially outwardly and engages an aperture 34 in band 20. The positions of the apertures in the band and the projections on the segments are coordinated such that the apertures receive the projections and maintain the segments in the desired relative spacing, engagement between the projections and the band limiting the relative motion between the band and the segments. In order to allow some free play permitting the segments 18 to shift circumferentially relatively to sealing member 12, the apertures 34 may be oversized holes or, as shown in Figure 6, they may comprise slots 36 that extend lengthwise along the band 20. Alternately, projections 32 may be relatively flexible or deformable to allow relative shifting of the segments when the tensioning member is tightened. Deformation may be elastic, plastic, or a combination of the two.
As shown in Figure 4, in an alternate embodiment of the coupling, segments 18 may have a projection 32 that is received within an indentation 38 in band 20. Indentation 38 may be elongated to allow some free play to the segments. Alternately, as shown in Figure 5, the projection 32 may be mounted on the band 20 and the indentation 38 which receives it is positioned in the segment 18.
As shown in Figure 2, segments 18 each have a pair of arcuate surfaces 40 and 42 positioned respectively on opposite sides of the sealing member 12. Arcuate surfaces 40 and 42 respectively engage outer surfaces 44 and 46 of pipe elements 48 and 50 when the tensioning member is tightened. Preferably, arcuate surfaces 40 and 42 project substantially radially inwardly and engage respective grooves 52 and 54 formed in the outer surfaces 44 and 46. Engagement between the arcuate surfaces and the grooves provides mechanical restraint to the joint and ensures that the pipe elements remain coupled even under high internal pressure and/or external force. Couplings 10 according to the invention may also be used with plain end pipe elements (described below) as well as with pipe elements that have shoulders proximate the ends or which have flared or expanded ends.
Arcuate surfaces 40 and 42 are positioned at the ends of segment sidewalls 56 and 60 that are joined by a back wall 62 and together form a channel 64 that receives the sealing member 12. Additional sidewalls 66 and 68 may also be extended radially outwardly to form a trough 70 that receives the band 20. Trough 70 helps keep the band properly engaged with the segments 18 during tightening of the tensioning member 26 by limiting the axial and rotational motion of the segments relatively to the band.
Installation of the banded coupling is described with respect to Figures 1, 2 and 2A. As shown in Figures 1 and 2, coupling 10 is sized with segments 18 spaced diametrically from one another such that pipe elements 48 and 50 may be inserted between the segments in end to end relationship. The pipe elements are received by the sealing element 12, which may have lips 72 that engage the pipe element outer surfaces 44 and 46 and use the internal pressure within the pipe elements to effect a tighter seal. Once both pipe elements are engaged within the coupling 10, the grooves 52 and 54, if present, are aligned with the arcuate surfaces 40 and 42 and the tensioning member 26 is tightened. As shown in Figure 2A, this forces the arcuate surfaces on each segment into engagement with the outer surfaces 44 and 46 of the pipe elements, in this example within grooves 52 and 54.
As shown in Figure 1, segments 18 have oppositely disposed end faces 74 and 76. End faces 74 and 76 are oriented substantially parallel to■ the longitudinal axis 78 of the pipe elements to be joined. As the tensioning member 26 is tightened, the end faces on adjacent segments move toward one another and the segments may be sized so that the end faces are in contact with one another to close off the entire outer surface 16 of the sealing member 12 when the arcuate surfaces 40 and 42 are engaged with grooves 52 and 54.
While projecting arcuate surfaces engageable with grooved pipes are a preferred embodiment, the coupling according to the invention may also be used to join plain end pipe elements. Such an embodiment 80 is shown in Figure 2B, wherein segments 18 have arcuate surfaces 40 and 42 that may- comprise a tooth or teeth 82 and 84. The teeth, when present, face substantially radially inwardly to grip the outer surface of plain pipe elements and provide mechanical restraint to the joint when the tensioning member of the coupling is tightened and the segments are forced into engagement with the pipe elements . The teeth may extend substantially continuously around the segment as illustrated by teeth 82, or they may be a single tooth 84, or a plurality of single teeth 84 spaced apart at intervals from one another.
In an alternate coupling embodiment 79, shown in Figures 3 and 3A, segments 18 have opposite end faces 86 and 88 that are angularly oriented with respect to the longitudinal axis 78 of the pipe elements. This angular orientation is best shown in Figures 7 and 7A. Figure 7 shows an axial view of a single segment 18 from coupling 79 wherein end faces 86 and 88 are visible. Figure 7A shows the segment 18 of Figure 7 as it would appear looking inwardly toward axis 78 to render the relative orientation of both end faces 86 and 88 visible and thus emphasize the angular relation between the end faces and the axis 78. Note that the end faces on each segment have opposite slopes. Furthermore, as shown in Figures 3 and 3A, the end faces 86 and 88 on neighboring segments 18 are substantially parallel to one another. In this embodiment, the segments are sized so that the end faces 86 on each segment engage the end faces 88 on each neighboring segment upon tightening of the tensioning member and as the arcuate surfaces begin to engage the outer surface of the pipe elements being joined together. The angular orientation of the end faces is such that forced contact between them (engendered by tightening of the tensioning member) causes neighboring segments to move in opposite directions to one another in the direction lengthwise along the pipe elements as shown in Figure 3A. Relative shifting of the segments 18 is advantageous when the coupling is used with grooved pipe because the lengthwise motion' of the segments forces the arcuate surfaces into engagement with the shoulders of the grooves and increases the stiffness of the joint about all of its axes.
In another coupling embodiment 90, shown in Figures 8 and 8A, segments 18 have end faces 92 and 94 that are angularly oriented with respect to the longitudinal axis 78 of the pipe elements. This angular orientation is best shown in Figures 9 and 9A. Figure 9 shows an axial view of a single segment 18 from coupling 90 wherein end face 92 is visible but end face 94 is hidden. Figure 9A shows the segment 18 of Figure 9 as it would appear looking inwardly toward axis 78 to render the relative orientation of both end faces 92 and 94 visible and emphasize the angular relation between the end faces and the' axis 78. Note that the end faces on each segment have substantially the same slope. Furthermore, as shown in Figures 8 and 8A, the end faces 92 and 94 on neighboring segments 18 are substantially parallel to one another. In this embodiment, the segments are sized so that the end faces 92 on each segment engage the end faces 94 on each neighboring segment upon tightening of the tensioning member and as the arcuate surfaces begin to engage the outer surface of the pipes being joined together. The angular orientation of the end faces is such that forced contact between them (engendered by tightening of the tensioning member) causes neighboring segments to rotate in opposite directions to one another about respective radii 96 and 98 extending outwardly from axis 78 as shown in Figure 8A. Relative rotation of the segments 18 is again advantageous when the couplin'g is used with grooved pipe because the rotational motion of the segments forces the arcuate surfaces into engagement with the shoulders of the grooves and increases the stiffness of the joint about all of its axes. Pipe couplings having compression bands according to the invention provide for rapid and sure installation, creating a pipe joint while avoiding the' need to partially or totally disassemble and then reassemble the coupling and handle the individual piece parts.