Abstract:
A coupling for joining pipe elements in end to end relationship is disclosed. The coupling includes a sealing member having an inner diameter and an outer surface. A plurality of segments are supported on the sealing member&#39;s outer surface. Each segment has a pair of arcuate surfaces positioned in space relation on either side of the sealing member. A compression band surrounds the outer perimeter of the segments, the segments being captured between the band and the sealing member. The pipe elements are inserted into the inner diameter between the segments. A tensioning member is mounted on the band. Tightening of the tensioning member causes the compression band to force the segments radially inwardly into engagement with outer surfaces of the pipe elements.

Description:
FIELD OF THE INVENTION  
       [0001]     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  
       [0002]     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.  
         [0003]     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.  
         [0004]     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.  
         [0005]     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&#39; 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.  
         [0006]     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  
       [0007]     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.  
         [0008]     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.  
         [0009]     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.  
         [0010]     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.  
         [0011]     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  
       [0012]      FIG. 1  is an axial cross-sectional view of a coupling according to the invention;  
         [0013]      FIG. 1A  is an axial cross-sectional view of an alternate embodiment of a coupling according to the invention;  
         [0014]      FIGS. 2, 2A  and  2 B are longitudinal sectional views of the coupling shown in  FIG. 1 ;  
         [0015]      FIGS. 3 and 3 A are side views of a coupling embodiment according to the invention;  
         [0016]      FIG. 4  is a partial axial cross-sectional view showing a detail of a coupling according to the invention;  
         [0017]      FIG. 5  is a partial axial cross-sectional view showing a detail of a coupling according to the invention;  
         [0018]      FIG. 6  is a perspective view showing a detail of a coupling according to the invention;  
         [0019]      FIG. 7  is an axial view of a segment used with the coupling shown in  FIG. 3 ;  
         [0020]      FIG. 7A  is a side view of the segment shown in  FIG. 7 ;  
         [0021]      FIGS. 8 and 8 A are side views of a coupling embodiment according to the invention;  
         [0022]      FIG. 9  is an axial view of a segment used with the coupling shown in  FIG. 8 ; and  
         [0023]      FIG. 9A  is a side view of the segment shown in  FIG. 9 .  
     
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS  
       [0024]      FIG. 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 .  
         [0025]      FIG. 1A  illustrates an alternate coupling embodiment  11  wherein compression band  20  is divided into a plurality of band portions, in this example, two portions,  20   a  and  20   b . Each band portion has opposite ends  22   a  and  24   a , and  22   b  and  24   b  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,  22   a  and  24   b , and  22   b  and  24   a , are joined by respective tensioning members  26   a  (mounted between  22   a  and  24   b ) and  26   b  (mounted between  22   b  and  24   a ). Each tensioning member preferably also comprises a bolt  28 , mounted on one end of a band portion ( 22   a  and  22   b ), the bolt engaging a threaded body  30  mounted on the adjacent end portion ( 24   a ,  24   b ). 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.  
         [0026]     With reference again to  FIG. 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  FIG. 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.  
         [0027]     As shown in  FIG. 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  FIG. 5 , the projection  32  may be mounted on the band  20  and the indentation  38  which receives it is positioned in the segment  18 .  
         [0028]     As shown in  FIG. 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.  
         [0029]     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.  
         [0030]     Installation of the banded coupling is described with respect to  FIGS. 1, 2  and  2 A. As shown in  FIGS. 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  FIG. 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 .  
         [0031]     As shown in  FIG. 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 .  
         [0032]     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  FIG. 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.  
         [0033]     In an alternate coupling embodiment  79 , shown in  FIGS. 3 and 3 A, 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  FIGS. 7 and 7 A.  FIG. 7  shows an axial view of a single segment  18  from coupling  79  wherein end faces  86  and  88  are visible.  FIG. 7A  shows the segment  18  of  FIG. 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  FIGS. 3 and 3 A, 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  FIG. 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.  
         [0034]     In another coupling embodiment  90 , shown in  FIGS. 8 and 8 A, 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  FIGS. 9 and 9 A.  FIG. 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.  FIG. 9A  shows the segment  18  of  FIG. 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  FIGS. 8 and 8 A, 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  FIG. 8A . Relative rotation of the segments  18  is again advantageous when the coupling 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.  
         [0035]     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.