Abstract:
In an aspect a pipe coupling arrangement includes two end members, each having a pipe attachment end and a sealing end that engages the other&#39;s sealing end. Each sealing end includes radially inner and outer collars, which are radially separated by a pocket. When the sealing ends engage one another the pockets form a chamber. At least one seal member is positioned in the chamber. An alignment ring fits in the chamber, aligning the end members. A coupling pushes the end members towards each other, compressing the at least one seal member sufficiently to seal against fluid leakage. The inner collars engage one another while the outer collars of the end members are axially spaced apart by a gap selected to reduce to zero upon application of a selected clamping force on the end members, thereby limiting deformation of the outer collars.

Description:
FIELD 
       [0001]    The present disclosure relates to the field of industrial pipe couplings, and in particular to a pipe coupling having improved contact performance at the contact interface. 
       BACKGROUND 
       [0002]    Industrial piping systems, such as those used for hydrocarbon transport/distribution, employ a variety of pipe coupling arrangements to join together lengths of pipe. Such systems typically convey fluids, in liquid or gaseous form, requiring a high performance sealing arrangement to prevent the egress of fluid from the piping system. 
         [0003]    Coupling arrangements sometimes incorporate mutually engaged flanged end members with mechanical gaskets (e.g. elastomeric members) between the mutually engaged faces of the end members, to ensure a sealed connection. Such systems depend on deformation of the mechanical gasket to provide a sealing interface. Over time, such systems can begin to leak due to degradation of the mechanical seal. 
         [0004]    There is a continuing need to develop pipe coupling systems having improved sealing performance, to ensure the safe transport of fluids, in particular for industrial application. 
       SUMMARY 
       [0005]    According to an aspect a pipe coupling arrangement for connecting two pipes is provided. The pipe coupling arrangement includes a pair of end members that are generally annular. Each end member has a pipe attachment end configured for attachment to a respective one of the two pipes. Each end member further has a sealing end configured to engage the sealing end of the other end member. The sealing end of each end member includes a radially inner collar and a radially outer collar and a pocket between the radially inner and outer collars. When the sealing ends engage one another the pockets together form a chamber. At least one seal member is provided and is positioned in the chamber. An alignment ring is provided and is sized to fit in the chamber to align the pair of end members so as to be coaxial with one another. The alignment ring has an axial length. A coupling is provided and is configured to impart a selected clamping force upon the end members towards each other, so as to compress the at least one seal member sufficiently to cause the at least one seal member to seal against leakage of fluid from within the pipes therepast. The radially outer and inner collars are arranged such that, when the inner collars of the end members engage one another at an inner collar interface, the outer collars of the end members are axially spaced from one another by a gap that is sized to prevent escape of the alignment ring and the at least one seal member from the chamber. 
         [0006]    In another aspect, a pipe coupling arrangement for connecting two pipes is provided. The pipe coupling arrangement includes a pair of end members that are generally annular. Each end member has a pipe attachment end configured for attachment to a respective one of the two pipes. Each end member further has a sealing end configured to engage the sealing end of the other end member. The sealing end of each end member includes a radially inner collar and a radially outer collar and a pocket between the radially inner and outer collars. When the sealing ends engage one another the pockets together form a chamber. At least one seal member is positioned in the chamber. Each seal member from the at least one seal member has an axial length. A coupling is provided and is configured to impart a selected clamping force upon the end members towards each other, so as to compress the at least one seal member sufficiently to cause the at least one seal member to seal against leakage of fluid from within the pipes therepast. The radially outer and inner collars are arranged such that, when the inner collars of the end members engage one another at an inner collar interface, the outer collars of the end members are axially spaced from one another by a gap that is sized to prevent escape of the alignment ring and the at least one seal member from the chamber. 
     
    
     
       BRIEF DESCRIPTION OF FIGURES 
         [0007]    The foregoing and other features and advantages of the disclosure will be apparent from the following description of embodiments hereof as illustrated in the accompanying drawing. The accompanying drawings, which are incorporated herein and form a part of the specification, further serve to explain the principles of the disclosure and to enable a person skilled in the pertinent art to make and use the disclosure. The drawings are not to scale. 
           [0008]      FIG. 1 a    is a partial perspective view of a pipe coupling arrangement according to a first embodiment hereof. 
           [0009]      FIG. 1 b    is an elevation view of a portion of the pipe coupling arrangement. 
           [0010]      FIG. 2  is a partial exploded sectional view of the pipe coupling according to the embodiment of  FIG. 1   a.    
           [0011]      FIG. 3  is a fully exploded partial sectional view of the pipe coupling according to the embodiment of  FIG. 1   a.    
           [0012]      FIG. 4  is a partial sectional view of a pipe coupling according to a second embodiment hereof. 
           [0013]      FIG. 5  is an exploded partial sectional view of the pipe coupling according to the embodiment of  FIG. 4 . 
           [0014]      FIG. 6  is a partial sectional view of the pipe coupling according to a third embodiment hereof. 
           [0015]      FIG. 7  is an exploded partial sectional view of the pipe coupling according to the embodiment of  FIG. 6 . 
           [0016]      FIG. 8  is a partial sectional view of the pipe coupling according to a forth embodiment hereof. 
           [0017]      FIG. 9  is an exploded partial sectional view of the pipe coupling according to the embodiment of  FIG. 8 . 
       
    
    
     DETAILED DESCRIPTION 
       [0018]    The following detailed description is merely exemplary in nature and is not intended to limit the disclosure or the application and uses of the disclosure. A person skilled in the relevant art will recognize that other configurations and arrangements can be used without departing from the scope of the disclosure. Furthermore, there is no intention to be bound by any expressed or implied theory presented in the preceding technical field, background, brief summary, or the following detailed description. 
         [0019]    Referring now to  FIGS. 1 a   - 3 , illustrated is a first embodiment of a pipe coupling arrangement  10  used to connect two sections of pipe, shown at  26  and  28 . The sections of pipe  26  and  28  may, for convenience also be referred simply as two pipes  26  and  28 . The pipe coupling arrangement  10  comprises a pair of generally annular end members  20  and  20 ′ that engage one another to form a contact seal. In the embodiment shown, the end members  20  and  20 ′ are formed with identical sectional profiles, however they need not have precisely identical sectional profiles for them to form a contact seal. The end members  20  and  20 ′ are urged together by a coupling  22  which is adapted to apply axial forces to the respective end members  20  and  20 ′ urging the end members  20  and  20 ′ towards each other. 
         [0020]    Each end member  20  and  20 ′ has a pipe attachment end  24  configured for attachment to a respective one of the two pipes  26  or  28 . The pipe attachment end  24  may be attachable to the corresponding pipe  26  or  28  in any suitable way. For example, both the pipe attachment end  24  and the corresponding mating end (shown at  32 ) of the pipe  26  or  28  may each be provided with a bevel  30 , so that the bevels  30  together form a valley suitable for receiving a circumferential weld. Alternatively, the end members  20  and  20 ′ may be sized to slip over the end  32  of the pipe  26  and  28 , and a suitable weld such as a fillet weld may be used to join the end members  20  and  20 ′ to the respective pipes  26  and  28 , thereby eliminating the need for the bevels  30 . 
         [0021]    The end members  20  and  20 ′ may be made from any suitable material, such as steel particularly where the pipes  26  and  28  are made from steel. 
         [0022]    The end members  20  and  20 ′ each include a sealing end  34  opposite the pipe attachment end  24 . The sealing end  34  of each end member  20  or  20 ′ is configured to engage the sealing end  34  of the other end member  20  or  20 ′. As shown in  FIGS. 1 a   - 3  the sealing end  34  of each end member  20  and  20 ′ includes a radially inner collar  54  and a radially outer collar  56 . The radially inner and outer collars  54  and  56  are radially separated from one another. A pocket  52  is positioned between the inner and outer collars  54  and  56 . When the sealing ends  34  engage one another (as shown in  FIGS. 1 a    and  2 ) the inner collars  54  of the end members  20  and  20 ′ engage one another at an inner collar interface  38 , and the pockets  52  together form a chamber  53 . The outer collars  56  do not engage one another but are instead spaced apart by a gap G ( FIG. 2 ). 
         [0023]    Put another way, the radially inner and outer collars  54  and  56  of the end members  20  and  20 ′ are arranged such that, when the inner collars  54  engage one another at the inner collar interface  38  (e.g. when the mutually facing surfaces  58  of the inner collars  54  engage one another), the outer collars  56  (more specifically the mutually facing surfaces  60  of the outer collars  56 ) are axially spaced from one another by the gap G. By ensuring that the gap G is present at the outer collars  156 , the inner collars  154  are assured of contacting one another, thereby reducing the pressure of any fluid that escapes past the interface  38 . The gap G is selected to be sufficiently small to prevent any of the components present in the chamber  53  from escaping, such as the alignment ring  64  and the seal members  68 . 
         [0024]    An alignment ring  64  is provided and is sized to fit in the chamber  53  to align the end members  20  and  20 ′ and to hold the end members in a coaxial relationship with one another until the coupling  22  is installed and sufficiently tightened on the end members  20  and  20 ′. To this end, the alignment ring  64  may have a radially inner surface  65  ( FIG. 2 ) that engages a radially outwardly facing wall  67  in the pocket  52  of each of the end members  20  and  20 ′. Alternatively, the alignment ring  64  could instead engage with its radially outer surface against a radially inwardly facing wall in the pocket of each of the end members  20  and  20 ′. 
         [0025]    The alignment ring  64  is shown as having a generally rectangular cross-sectional shape. The chamber  53  may also have a generally rectangular cross-sectional shape. 
         [0026]    Optionally, each pocket  52  includes an axial limit surface  69  such that the axial limit surfaces  69  together control axial positioning of the alignment ring  64  in the chamber  53  so as to cause the alignment ring  64  to cover the inner collar interface  38 , and to cause the alignment ring  64  engage both end members  20  and  20 ′. 
         [0027]    At least one seal member  68  is positioned in the chamber  53 . In the example shown in  FIGS. 1-3 , two seal members  68  are shown, which may be referred to as first and second seal members  68 . More specifically, the alignment ring  64  has a first axial end surface  61  and a second axial end surface  63 . The first and second seal members  68  are positioned to be compressed between the respective first and second axial end surfaces  61  and  63  of the alignment ring  64  and opposing sealing surfaces  71  and  73  of the chamber  53 . The sealing surfaces  71  and  73  may be provided in circumferential seal channels  66 . The seal members  68  may be any suitable type of seal members such as, for example, O-rings, which may be made from urethane or from any other suitable material. 
         [0028]    The coupling  22  is configured to impart a selected clamping force (i.e. the aforementioned axial forces) upon the end members  20  and  20 ′ so as to urge the end members  20  and  20 ′ towards each other, so as to compress the at least one seal member  68  (e.g. the two seal members  68  in the embodiment shown in  FIGS. 1 a   - 3 ) sufficiently to cause the at least one seal member  68  to seal against leakage of fluid from within the pipes  26  and  28  therepast (i.e. past the at least one seal member  68 ). The clamping force is achieved by engagement of first angled surfaces  45  in a channel  44  in the coupling  22 , which matingly engage second angle surfaces  42  on the end members  20  and  20 ′. The term ‘angled’ in this case means that the surfaces  45  and  42  extend at some non-zero angle relative to the pipe axes, which are shown at A. By angling the surfaces  45  and  42  to have a non-zero angle with one another, tightening of the coupling  22  increases the clamping force exerted by the coupling  22  on the end members  20  and  20 ′. However, it is possible to provide an embodiment in which the surfaces  45  and  42  extend directly radially. The tightening of the coupling  22  so as to apply a clamping force on the end members  20  and  20 ′ may be by any suitable means. For example, the coupling  22  may include a plurality of coupling segments (e.g. two coupling segments  22   a  and  22   b ) which all straddle the surfaces  42  on the two end members  20  and  20 ′ and which have fastener apertures  50  which are aligned so that fasteners (shown at  51  in  FIG. 1 b   ) can be inserted through the apertures  50  to lock the coupling segments  22   a  and  22   b . Suitable fasteners  51  include, for example, bolts with nuts. 
         [0029]    Reference is made to  FIGS. 4 and 5 , which show a second embodiment of a pipe coupling arrangement  110  that is similar to the pipe coupling arrangement  10  in  FIGS. 1 a   - 3 . Structure in  FIGS. 4 and 5  that is similar to structure shown in  FIGS. 1 a   - 3  is denoted with a reference number that is the same as the corresponding reference number in  FIGS. 1 a   - 3 , but increased by 100. The pipe coupling arrangement  110  comprises a pair of end members  120  and  120 ′ that engage to form a contact seal therebetween. 
         [0030]    Thus, the end members  120  and  120 ′ each include a sealing end  134  that is similar to the sealing end  34 , and a pipe attachment end  124  that is similar to the pipe attachment end  24 . The sealing end  134  includes radially inner and outer collars  154  and  156  which are arranged such that, when the inner collars  154  (e.g. the first mutually facing surfaces  158 ) engage one another at the inner collar interface shown at  138 , the outer collars  156  (e.g. the second mutually facing surfaces  160 ) are axially spaced from one another by a gap G. 
         [0031]    As described above in relation to the coupling arrangement  10  shown in  FIGS. 1 a   - 3 , the gap G is present at the outer collars  156  to ensure that the inner collars  154  are assured of contacting one another, thereby reducing the pressure of any fluid that escapes past the interface  138 . The gap G is selected to be sufficiently small to prevent any of the components present in the chamber  153  from escaping, such as the alignment ring  164  and the seal member  168 . 
         [0032]    In the embodiment shown in  FIGS. 4 and 5 , each end member  120  or  120 ′ has a pocket  152  that is provided between the inner and outer collars  154  and  156 . When the sealing ends  134  are engaged with one another, the pockets  152  together form a chamber  153 . There is an alignment ring  164  that is positioned in the chamber  153  between two opposing axial limit surfaces  169  which are similar in function to the surfaces  69 . 
         [0033]    A difference in the embodiment shown in  FIGS. 4 and 5  and the embodiment shown in  FIGS. 1 a   - 3  is that there is a single seal member shown at  168 , which may be similar to the seal members  68 , and which is positioned radially offset (in this example, radially inside) of the alignment member  164  between two opposing sealing surfaces  171  and  173  on the end members  120  and  120 ′. The seal member  168  is positioned in a single circumferentially extending seal channel  166  that is defined in part by the two sealing surfaces  171  and  173 . The seal member  168  compresses against the sealing surfaces  171  and  173  so as to seal against the leakage of fluid from within the pipes  26  and  28  therepast. Because the seal member  168  seals against surfaces of the chamber  153  (i.e. surfaces  171  and  173 ) and is radially inside of the alignment ring  164 , the seal member  168  substantially prevent contact between the fluid in the pipes  26  and  28  and the alignment ring  164 . 
         [0034]    To inhibit pinching of the seal member  168  during engagement of the inner collars  154 , the inner diameter of the seal member  168  may be made larger than the outer diameter of the inner collars  154 . 
         [0035]    Another difference in the embodiment shown in  FIGS. 4 and 5  and the embodiment shown in  FIGS. 1 a   - 3  is that the alignment ring  164  has an optional, generally pentagonal cross-sectional shape, which includes circumferentially extending surfaces  164   a  and  164   b  which are at a non-zero angle relative to one another. 
         [0036]    Reference is made to  FIGS. 6 and 7 , which shows a pipe coupling arrangement  210  according to another embodiment. The pipe coupling arrangement  210  has an alternative arrangement of the alignment ring and the seal member, shown at  264  and  268  respectively. Structure in  FIGS. 6 and 7  that is similar to structure shown in  FIGS. 4-5  is denoted with a reference number that is the same as the corresponding reference number in  FIGS. 4-5 , but increased by 100. The pipe coupling arrangement  210  includes a pair of end members  220  and  220 ′ that engage to form a contact seal therebetween. 
         [0037]    The end members  220  and  220 ′ each have a sealing end  234  which coaxially align with one another and which engage at a sealing interface  238 . As shown, the sealing ends  234  of the end members  220  and  220 ′ are each configured with a circumferential pocket  252  defined by a radially inner collar  254  and a radially outer collar  256 . When the sealing ends  234  are engaged with one another, the pockets  252  together form a chamber  253  in which the seal member  268  is positioned. 
         [0038]    The inner collars  254  have mutually facing surfaces  258 , while the outer collars  256  have mutually facing surfaces  260 . 
         [0039]    A difference between the pipe coupling arrangement  210  and the pipe coupling arrangement  10  is that the alignment member  264  and the seal member  268  are kept in separate chambers. More particularly, the outer collars  256  are first outer collars, and each sealing end  234  includes a second outer collar  257  that is radially spaced from both the first outer collar  256  and the inner collar  254 , such that the pocket  252  (which may be referred to as the first pocket  252 ) is provided immediately between the inner collar  254  and the second outer collar  257  and a second pocket  259  is provided immediately between the second outer collar  257  and the first outer collar  256 . Thus, both pockets  252  and  259  are provided between the inner and outer collars  254  and  256 . When the sealing ends  234  engage one another the pockets  252  (which may be referred to as the first pockets  252 ) together form the chamber  253  as noted above (which may be referred to as the first chamber  253 ), and the second pockets  259  together form a second chamber  274 . 
         [0040]    The inner collars  254  have mutually facing surfaces  258 , the first outer collars  256  have mutually facing surfaces  260  and the second outer collars  257  have mutually facing surfaces  275 . When the inner collars  254  (e.g. the first mutually facing surfaces  258 ) engage one another at the inner collar interface shown at  238 , the first outer collars  256  (e.g. the mutually facing surfaces  260 ) and the second outer collars  247  (e.g. the mutually facing surfaces  275 ) are axially spaced from one another by gaps G and G 2  respectively. By ensuring that the gaps G and G 2  are present at the outer collars  256  and  257 , the inner collars  254  are assured of contacting one another, thereby reducing the pressure of any fluid that escapes past the interface  238 . The gaps G and G 2  are selected to be sufficiently small to prevent any of the components present in the chambers  253  and  274  from escaping, such as the alignment ring  64  and the seal member  68 . 
         [0041]    The alignment ring  264  is sized to fit in the second chamber  274  to align the pair of end members  220  and  220 ′ so as to be coaxial with one another. 
         [0042]    Referring to  FIGS. 8 and 9 , a pipe coupling arrangement  310  is shown and includes a pair of annular end members  320  and  320 ′ that engage to form a contact seal therebetween using a seal member  368 . A coupling  322  is provided for applying a clamping force to the end members  320  and  320 ′, and an optional alignment ring  364  is shown. In  FIGS. 8 and 9 , structure similar to that described above with reference to  FIGS. 4 and 5  includes the same reference number increased by 200. 
         [0043]    Each end member  320  and  320 ′ includes a sealing end  334 , and a pipe attachment end  324 . The sealing end  334  includes radially inner and outer collars  354  and  356  which are arranged such that, when the inner collars  354  (e.g. the first mutually facing surfaces  358 ) engage one another at the inner collar interface shown at  338 , the outer collars  356  (e.g. the second mutually facing surfaces  360 ) are axially spaced from one another by a gap G. As described above in relation to the coupling arrangement  10  shown in  FIGS. 1 a   - 3 , the gap G is present at the outer collars  356  to ensure that the inner collars  354  are assured of contacting one another, thereby reducing the pressure of any fluid that escapes past the interface  338 . The gap G is selected to be sufficiently small to prevent any of the components present in the chamber  353  from escaping, such as the alignment ring  364  and the seal member  368 . 
         [0044]    The alignment ring  364  has an optional, generally trapezoidal cross-sectional shape, which includes circumferentially extending surfaces  364   a  and  364   b  which are at a non-zero angle relative to one another. The chamber in which the alignment member  364  is positioned, shown at  353 , has corresponding angled chamber surfaces that mate with the surfaces  364   a  and  364   b.    
         [0045]    It will be appreciated that with respect to any of the embodiments detailed above, pocket and alignment ring configurations, in particular the cross-sectional profile may vary, as other profiles may be suitably implemented. 
         [0046]    While the pairs of end members shown in the figures are shown having identical sectional profiles, it will be appreciated that a pair of end members may include two end members having structural differences from one another. For example, while the various contact interfaces detailed above may remain substantially as described, one of the end members in the pair may be configured to be longer or present a bend therein for placement between two pipe sections that are angled relative to one another. 
         [0047]    It will be appreciated that, although embodiments of the disclosure have been described and illustrated in detail, various modifications and changes may be made. While preferred embodiments are described above, some of the features described above can be replaced or even omitted. Still further alternatives and modifications may occur to those skilled in the art. All such alternatives and modifications are believed to be within the scope of the disclosure.