Abstract:
Disclosed is a device for coupling a male piping member to a female piping member including a compressible sealing gasket and a gripping ring surrounding the male piping member, the gripping ring including at least one gripping member and at least one overlapping surface; an intermediate ring surrounding the male piping member, the intermediate ring at least partially overlapping the overlapping surface of the gripping ring, the intermediate ring communicating with the compressible sealing gasket; and a locking ring surrounding the male piping member and communicating with the gripping ring, wherein through a tightening connection between the locking ring and the female piping member, the locking ring communicates with the gripping ring forcing the intermediate ring into the compressible sealing gasket to form a seal between the male piping member and the female piping member and subsequently to force the gripping ring to grip the male piping member.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Application 61/308,549 filed on Feb. 26, 2010, which is hereby incorporated herein in its entirety by reference. 
     
    
     BACKGROUND 
       [0002]    The disclosure relates generally to fluid piping members. More particularly, the disclosure relates to the field of connections between lengths of pipe or between pipes and fittings. 
         [0003]    The construction of pipelines generally involves the axial connection of two lengths of pipe to form a single pipeline conduit for transporting materials from one point to another. Along the pipeline, one or more fittings may join the pipe pieces to other components in the pipeline. Due to the nature of the materials usually conveyed via pipelines, pipeline conduits, joints between axially-joined pieces of pipe, and joints between pipes and fittings need to be substantially leak-proof. 
         [0004]    Another important design requirement exists when it becomes necessary to join the pipe components in a restrained manner. This is usually desired in order to prevent the pipe components from separating due to thrust forces that often occur when the pipeline is subjected to internal pressure or when earth tremors or other external events occur. As such, the overall reliability of the piping system often depends on the stability of the couplings used throughout the system. Accordingly, the pipe industry has focused some attention on the problem of maintaining connections between adjacent lengths of pipe after installation. As a result, several attempted solutions and approaches are known in the art. Accordingly, a number of different arrangements have been developed in an attempt to provide secure couplings between pipe ends. It is known to employ gripping members in order to prevent uncoupling of pipe joints by longitudinal forces imposed on coupled pipe sections. Other arrangements include combinations of rings and seals that use compression-type connections to hold pipe systems together. For example, a gland and gripping ring may be used in combination to position, compress, and seal a gasket on a pipe. 
         [0005]    References to “pipe” with respect to the application or use of embodiments of the present disclosure shall be understood to include fittings, connections, and any other appurtenances to pipes. 
         [0006]    While the degree of pipe restraint on a coupled joint can be important, it can be equally important that an adequate gasket compression be achieved to ensure a correct seal against leaks in the piping system. Accordingly, typical bolt-type couplings having a gasket to effect sealing and a lock ring to restrain the coupled pipe against pull-out are common in the prior art. In these couplings, a gripping ring is imposed on the pipe, between the lock ring and the gasket, to operationally grip the pipe prior to or simultaneous with compression of the gasket. One drawback of such couplings, however, is that they can result in an undetectable but inadequate gasket seal because the gripping ring often engages the pipe and locks it into place before the seal is properly actuated. 
         [0007]    Accordingly, other compression couplings have been designed with various arrangements and parts to prevent gripping ring lock-up prior to compression of the sealing gasket. For example, U.S. Pat. No. 4,070,046 to Felker et al. discloses pipe couplings for both restraining and sealing the pipe ends. One major disadvantage of this design, however, is the timing of the gripping and sealing members&#39; actuation. Because the gripping members engage the pipe ends at very low torque, the follower member becomes locked onto the pipe end with this design. Accordingly, proper gasket compression can only be achieved by ensuring that there is a gap between the pipe ends and that at least one of the pipes is free to move axially into the coupling. These requirements make this design unsuitable for use in certain applications where such pipe movement is not possible. Another problem with this design is that gasket compression may be reduced when the coupled pipe is under an axial tension load because the gripping member supporting the gasket has a tendency to move away from the gasket. 
         [0008]    U.S. Pat. No. 4,569,542 to Anderson et al. discloses a bolt-type coupling designed to provide clearance functions, so that gasket compression is achieved before the gripping ring effectively grips the pipe and locks the coupling in place when the bolt fasteners are tightened. U.S. Pat. No. 5,803,513 to Richardson discloses the use of a plurality of skid pads strategically placed over the teeth of the gripping ring to prevent it from prematurely engaging the pipe before compressing the accompanying gasket. However, while the couplings disclosed by U.S. Pat. Nos. 4,569,542 and 5,803,513 are useful for their intended purpose, they require additional or complicated arrangements of parts, which may increase cost and/or hinder the ease of coupling installation. 
         [0009]    Another partial solution to these problems is proposed in U.S. Pat. No. 4,606,565 to Royston, which provides separate follower members for the gripping and the sealing members. With such a coupling, complete and repeatable gasket compression, as well as complete and repeatable gripping engagement, are possible regardless of installation conditions. While such a coupling solves the problems of gasket compression and gripping engagement, the design requires assembly of a number of pieces and proper tightening of twice as many bolts. Accordingly, the solution proposed in U.S. Pat. No. 4,606,565 overcomes the limitations of the other designs, but, the design increases the number of pieces and causes the installation of the device onto the pipe to be cumbersome and overly time consuming. 
         [0010]    Yet another solution to these problems has been described in U.S. Pat. No. 7,004,511 to Barron et al. in which an intermediate ring, located between a sealing gasket and a gripping ring, has a restraining member adapted for restraining the gripping ring to prevent the gripping members from gripping a male piping member until after the sealing gasket is compressed into sealing engagement with the male piping member and a female piping member. 
         [0011]    However, the reliability of the sealing arrangement between the female piping member, sealing gasket, and male piping member depends on a uniform distribution of a force compressing the sealing gasket especially in the long term. In order to achieve uniform force distribution, concentric location of the female piping member, male piping member, and coupling device element that compress the sealing gasket is desirable. The prior art does not offer a solution to this problem. 
         [0012]    There remains a need for an improved pipe coupling that provides a desired degree of sealing and gripping functions regardless of installation conditions, that is simple to install and manufacture, and that retains an appropriate seal over time. It is to such a pipe coupling that various embodiments of the present disclosure are primarily directed. 
     
    
     
       DESCRIPTION OF THE FIGURES 
         [0013]      FIG. 1  is a side cross-sectional view of a pipe coupling device, known in the art, before the bolts are tightened. 
           [0014]      FIG. 2  is a close-up view of detail A of the pipe coupling device, known in the art, shown in  FIG. 1 . 
           [0015]      FIG. 3  is a close-up view of detail B of the pipe coupling device, known in the art, shown in  FIG. 1 . 
           [0016]      FIG. 4  is an exploded view of a pipe coupling device in accordance with one embodiment of the present disclosure showing the arrangement of sealing elements. 
           [0017]      FIG. 5  is a side cross-sectional view of the assembled pipe coupling device of  FIG. 4  including a male pipe before the tightening members are tightened. 
           [0018]      FIG. 6  is a close-up view of detail C of the pipe coupling device, shown in  FIG. 5 . 
           [0019]      FIG. 7  is a side cross-sectional view of a female member of the pipe coupling device of  FIG. 5 . 
           [0020]      FIG. 8  is a sectional view of the female member in the cross-sectional plane indicated by line F in  FIG. 7 . 
           [0021]      FIG. 9  is a close-up view of detail G of the female member, shown in  FIG. 8 . 
           [0022]      FIG. 10  is a side cross-sectional view of the assembled pipe coupling device in accordance with one embodiment of the present disclosure after the tightening members are tightened. 
           [0023]      FIG. 11  is a perspective view of a gripping ring of the pipe coupling device of  FIG. 4 . 
           [0024]      FIG. 12  is a close-up view of detail D of the gripping ring, shown in  FIG. 11 . 
           [0025]      FIG. 13  is a perspective view of an intermediate ring of the pipe coupling device of  FIG. 4 . 
           [0026]      FIG. 14  is a close-up view of detail E of the intermediate ring, shown in  FIG. 13 . 
           [0027]      FIG. 15  is a perspective view of the gripping ring and the intermediate ring of the pipe coupling device of  FIG. 4 , wherein the gripping ring is in contact with the restraining member of the intermediate ring. 
           [0028]      FIG. 16  is a perspective view of the gripping ring and intermediate ring shown in  FIG. 15  after the restraining member of the intermediate ring has been disengaged by the gripping ring. 
       
    
    
     DETAILED DESCRIPTION 
       [0029]    To facilitate an understanding of the principles and features of the present disclosure, it is explained hereinafter with reference to its implementation in an illustrative embodiment. In particular, the present disclosure is described in the context of a pipe coupling device. 
         [0030]    Those skilled in the art will understand that the specificity provided herein is intended for illustrative purposes with respect to one of many possible embodiments and is not to be interpreted as limiting the scope of the claims. 
         [0031]    Embodiments of the present disclosure will be described primarily in conjunction with a pipe coupling device suitable for round cross-section fluid pipelines. It should be understood, however, that various embodiments can be utilized in conjunction with a variety of other applications, both in fluid pipe conduits and in other types of pipelines. For example, various embodiments may be utilized in conjunction with the gas pipelines and other applications requiring secure, fluid tight connection between adjacent piping conduits having various cross-sectional shapes. In addition, embodiments will be described primarily in the context of connecting female piping sections with male piping sections. However, it should be understood that embodiments may be used with a variety of fluid piping members, including adjoining male and female piping terminal fittings and other pipe fittings having openings configured to receive male piping members. Although an ordering of coupling elements is recited in example embodiments of this disclosure, no particular ordering of elements should be considered binding on the disclosure as a whole, and particular elements may be reordered, repositioned, replaced, or removed entirely from the assembly. Such modifications are to be considered to be captured by the present disclosure. Although the disclosure refers to diameters, the piping members in this arrangement may be non-circular in profile. Where a diameter is recited, the outer dimension of elements is intended to be referenced for non-circular elements. 
         [0032]    Referring now in detail to the drawing figures, wherein like reference numerals represent like parts throughout the several views,  FIGS. 1-3  illustrate the side cross-sectional view and the close-up views of the details of the pipe coupling device as it is known in the art, particularly, as described in U.S. Pat. No. 7,004,511. This pipe coupling device  10  includes a female member or female piping member  11  having an enlarged end portion  12  for receiving a male piping member  13 . The enlarged end portion  12  has a sealing cavity  14  defined between an outer surface  15  of the male piping member  13  and an interior surface  16  of the female piping member  11 . In addition, the female piping member  11  has a cylindrical area  23  to accommodate an interfacing end  31  of the male piping member  13  which extends longitudinally inward parallel to the pipe axis  24  and joins a shoulder region  25 . 
         [0033]    A sealing gasket  17  is adapted for arrangement within the sealing cavity  14  of the female piping member  11  for compression into sealing engagement with the outer surface  15  of the male piping member  13 . A gripping ring  18  is adapted for encircling the male piping member  13  and has a radial inner surface having a plurality of gripping members  19  for gripping the male piping member  13  upon coaxial compression of the gripping ring  18 . An intermediate ring  20  is adapted for encircling the male piping member  13  between the sealing gasket  17  and the gripping ring  18  and has a restraining member (not shown) adapted for restraining the gripping ring  18  to prevent the gripping members  19  from gripping the male piping member  13  until after the sealing gasket  17  is compressed into sealing engagement with the outer surface  15  of the male piping member  13 . A locking ring  21  is adapted for communication with the gripping ring  18 . At least two tightening members  22  are included for connecting the female piping member  11  and the locking ring  21  to compressibly secure the gripping ring  18  and sealing gasket  17  to the male piping member  13 , such that upon the tightening of the tightening members  22 , the sealing gasket  17  is compressed into sealing engagement followed by the gripping of the male piping member  13  by the gripping ring  18 . When the system is operational, tightening of the tightening members  22  forces the locking ring  21  closer to the female piping member  11 . The gripping ring  18  and intermediate ring  20  move together toward the sealing gasket  17 , eventually seating the sealing gasket  17  in the sealing cavity  14 . After sealing, further tightening of the tightening members  22  causes the gripping ring  18  to break the engagement with the restraining member (not shown) and lock onto the male piping member  13 . 
         [0034]    As described, the reliability of the sealing arrangement between the female piping member  11 , sealing cavity  14 , and male piping member  13  depends on a uniform distribution of a force compressing the sealing gasket  17 . Thus, a concentric arrangement of parts is desirable. 
         [0035]    The parts of the pipe coupling device  10  involved in the sealing arrangement, particularly the cylindrical area  23  of the female piping member  11 , the intermediate ring  20 , and the gripping ring  18 , can be developed in at least two different ways: they can be finished by machining or used “as cast.” Machining may deliver parts with a narrower field of tolerances and produce more concentric location of all parts involved in the sealing arrangement. However, the machining of all the parts is time-consuming and costly. 
         [0036]    On the other hand, less costly “as-cast” parts have much wider fields of tolerances, which widen further with an increase in the diameter of the pipe to be coupled. Large casting tolerances can result in non-concentric assembly of the male piping member  13  and the female piping member  11 . In particular, during field assembly, when the male piping member  13  is inserted into the female piping member  11 , the difference between an outside diameter of the male piping member  13  and an inside diameter of the cylindrical area  23  of the female piping member  11  can allow displacement of the male piping member  13  and can allow the outer surface  15  of the male piping member  13  to contact an inner surface  26  of the cylindrical area  23  (see  FIGS. 2 and 3 ) such that the interfacing end  31  of the male piping member  13  moves within the cylindrical area  23  so that the axis  24  of the male piping member  13  is not coaxial with the female piping member  11 , creating a circumferentially non-uniform space between the male piping member  13  and the cylindrical area  23 , leading to improper seal between the male piping member  13 , the female piping member  11 , and the sealing gasket  17  (as seen in  FIGS. 1-3 ). Depending on cast tolerances, the intermediate ring  20  may drop until an inner surface  27  of the intermediate ring  20  approaches the outer surface  15  of the male piping member  13  (as seen in  FIG. 2 ), potentially contacting it, or the intermediate ring  20  may drop until an outer surface  28  of the intermediate ring  20  approaches the interior surface  16  of the female piping member  11  (as seen in  FIG. 3 ), potentially contacting it. The result is that the mating surfaces of the sealing gasket  17  and of the intermediate ring  20  are eccentric and produce non-uniform loading of the sealing gasket  17 . The effect of these factors can breach the sealing arrangement between the male piping member  13 , sealing gasket  17 , and female piping member  11 , especially in the long term. Also, even if machined, the sealing elements can become off-centered around piping with wider tolerances than the sealing elements and lead to the incomplete sealing engagement described above. 
         [0037]      FIGS. 4 through 16  illustrate an embodiment of a coupling device  100 . More specifically,  FIG. 4  presents an exploded view of the coupling device  100 , and  FIG. 5  illustrates the side cross-sectional view of the coupling device  100  in a first position, wherein tightening members  101  have not been tightened. A female piping member  150  and a locking ring  350  cooperate with sealing elements (a gripping ring  300 , an intermediate ring  250 , and a sealing gasket  200 ) to form a fluid-tight seal on a male piping member  125  as shown in  FIG. 10 . In various embodiments, the female piping member  150  may be a piping, a fitting, a coupling, a joint, another piping element, or a portion of any of the foregoing. 
         [0038]    The arrangement of the sealing elements is illustrated in the exploded view of  FIG. 4 . As shown, the gripping ring  300  is positioned adjacent to the locking ring  350 , and the intermediate ring  250  is positioned between the gripping ring  300  and the sealing gasket  200 . In operation, the sealing elements abut one another to compress the sealing gasket  200 , forming a fluid tight seal between the male piping member  125  and the female piping member  150  as described below. The intermediate ring  250  may include one or more restraining members  251  (see  FIGS. 13 and 14 ) that communicate with a slot  301  on the gripping ring  300  (see  FIGS. 4 ,  11  and  12 ) and prevent the gripping ring  300  from engaging an outer surface  126  of the male piping member  125  until after the sealing gasket  200  has been compressed. Although the restraining member  251  is placed on the intermediate ring  250  in the current embodiment, the restraining member may be included on or integrated with the locking ring  350  or the gripping ring  300 . 
         [0039]    As shown in  FIGS. 5-7 , the female piping member  150  includes a front wall  152  and a retaining wall  153  on an enlarged end portion  161  of the female piping member. Along with the male piping member  125  and the intermediate ring  250 , the front wall  152  and retaining wall  153  of the female piping member  150  create a sealing cavity  151  around the male piping member  125  for placement of the sealing gasket  200 . In addition, the female piping member  150  has a cone-shaped portion  154  which joins a shoulder region  155  (see  FIG. 7 ). The cone-shaped portion  154  is a region of the female piping member  150  with an opening diameter or width initially larger than the outer diameter or width of the male piping member  125  wherein the opening diameter or width gradually reduces radially along the length of the female piping member  150  and wherein the gradual reduction in diameter or width terminates at an opening diameter or width that is smaller than the outer diameter or width of the male piping member  125 . The cone-shaped portion  154  has a larger end  162  and a smaller end  158 . The cone-shaped portion  154  is dimensioned so that the largest possible diameter of the smaller end  158  of the cone-shaped portion  154  is not larger than the smallest possible diameter of an engagement end  130  of the male piping member  125 . This arrangement allows for the engagement end  130  of the male piping member  125  to be centrally located with respect to the female piping member  150  without any dependency on the outside diameter of the male piping member  125  or the cast tolerances of the female piping member  150  and substantially ensures a uniform sealing cavity  151  about the male piping member  125 . Although the cone-shaped portion  154  of the female piping member  150  is defined as a cone in the current embodiment, any reducing diameter profile may serve the same purpose and is intended to be included within the definition of the cone-shaped portion  154 . 
         [0040]    The female piping member  150  also may have a flange  156 , which may include a plurality of apertures  157  to receive the tightening members  101  as it will be described below. In addition, the female piping member  150  may also have at least one media channel  159  (see  FIGS. 6-9 ) for delivering media pressure to the back of the sealing gasket  200  to increase its compression. The cross-sectional profile of each at least one media channel  159  is semi-circular in the current embodiment (see  FIG. 9 ), although other cross-sectional profiles are contemplated by this disclosure. 
         [0041]    The sealing gasket  200  may be in the form of a variety of different cross-sectional shapes. For instance, the sealing gasket  200  may have a cross-sectional shape that matches the shape of the sealing cavity  151  of the female piping member  150 . The sealing gasket  200  may also be a simple O-ring. In various embodiments, the sealing gasket  200  has a “filled figure-8” cross-sectional shape (see  FIG. 6 ). In various other embodiments, two O-rings or other gaskets with the same or similar cross-sectional shapes may also be used. The sealing gasket  200  is designed to be compressible and is made from rubber, elastomer, silicone, or other compressible sealing material. 
         [0042]    As seen in  FIG. 6 , to improve the compression of the sealing gasket  200 , a gasket mating surface  252  of the intermediate ring  250  that mates with the sealing gasket  200  is substantially slanted to the same degree as the front wall  152  of the sealing cavity  151  of the female piping member  150 . When nuts  102  are tightened on the end of the tightening members  101 , the sealing gasket  200  is compressed between the gasket mating surface  252  of the intermediate ring  250  and the front wall  152 . Through the compression, the gasket mating surface  252  radially forces a portion of the sealing gasket  200  toward the retaining wall  153  while the front wall  152  radially forces another portion of the sealing gasket  200  toward the male piping member  125 . Thus, once the sealing gasket  200  is compressed between the gasket mating surface  252  and the front wall  152 , the radial arrangement of the sealing gasket  200  will substantially assure a leak proof seal. 
         [0043]    In various embodiments, the end of the intermediate ring  250  opposite to the gasket mating surface  252  has an overlapping surface  253  to provide a stable engagement with an intermediate-ring-side overlapping surface  302  positioned on the side of the gripping ring  300  that interfaces with the intermediate ring  250 . In the current embodiment, the intermediate-ring-side overlapping surface  302  of the gripping ring  300  is an outer cone-shaped surface. The overlapping surface  253  of the intermediate ring  250  is an inner cone-shaped surface. Other overlapping profiles are contemplated by this disclosure. 
         [0044]    The intermediate ring  250  may further include at least one restraining member  251  (see  FIGS. 13-15 ) to prevent the gripping ring  300  from engaging the male piping member  125  and locking the coupling in place until a proper seal has been achieved. The restraining member  251  may be carried as a separate component, may be integral with the intermediate ring  250  (as shown in the current embodiment) or the locking ring  350 , or may be integral with the gripping ring  300 . The restraining member  251  is aligned with the slot  301  of the gripping ring  300  for positioning within the slot  301  during compression. The restraining member  251  has a predetermined retention force for preventing radial inward movement of the gripping ring  300  until sufficient force is applied to disengage the restraining member  251 . The force required to compress the slot  301  from its first position (see  FIG. 15 ) to its second position (see  FIG. 16 ) by disengaging the restraining member  251  is greater than the force required to compress the sealing gasket  200 . A radial inner surface of the gripping ring  300  further may include a plurality of gripping members  304  (see  FIGS. 11 and 12 ) extending radially inwardly and adapted to engage the outer surface  126  of the male piping member  125  upon coaxial compression of the gripping ring  300 . In the current embodiment, the gripping members  304  are teeth, although other types of gripping members are contemplated within this disclosure. When the gripping ring  300  moves from its first position to its second position, the gripping members  304  move into a gripping engagement with the male piping member  125  and thereby secure the coupling device  100  in the second position of  FIG. 16 . The restraining member  251  may be at least one break-off member as shown in  FIGS. 13-15  or at least one deformable member designed to bend or crush rather than break off. 
         [0045]    The longitudinally extending slot  301  of the gripping ring  300  has a predetermined width to accommodate reduction of the circumference of the gripping ring  300  upon coaxial compression of the gripping ring  300  by the radial interior of the locking ring  350  due to an interaction between an overlapping surface  351  of the locking ring  350  and a locking-ring-side overlapping surface  303  of the gripping ring  300 . The locking-ring-side overlapping surface  303  of the gripping ring  300  and the intermediate-ring-side overlapping surface  302  of the gripping ring  300  are shown as outer cone-shaped surfaces in the current embodiment. The overlapping surface  351  of the locking ring is shown as an inner cone-shaped surface in the current embodiment. 
         [0046]    In various embodiments, each of the gripping members  304  of the gripping ring  300  may be provided with a radially extending surface and an angled backup surface which meet to form an inner edge. Accordingly, the width of the slot  301  of the gripping ring  300  may be compressed from a first position (see  FIG. 15 ), where the gripping members  304  of the gripping ring  300  do not grip the male piping member  125 , to a second position (see  FIG. 16 ), where the slot  301  has a smaller width and the gripping members  304  of the gripping ring  300  engage or grip the outer surface  126  of the male piping member  125 . 
         [0047]    The coupling device  100  includes the locking ring  350  that surrounds and abuts the gripping ring  300 , which is in communication with the intermediate ring  250 . The intermediate ring  250  abuts the sealing gasket  200 . The sealing gasket  200  abuts the slanting front wall  152  of the female piping member  150 . The locking ring  350  may have two or more apertures  352  for receiving the tightening members  101  so that the bolts will each extend through the aperture  352  and through the aperture  157  in the flange  156  of the female piping member  150 . In various embodiments, the tightening members  101  may have an anchoring portion or catch (not shown) opposite the threaded end to facilitate engagement between the locking ring  350  and the flange  156  of the female piping member  150  as the nuts  102  are tightened. With this arrangement, tightening the nuts  102  on the threaded ends of the tightening members  101  secures the sealing elements together and assures a fluid tight seal. Although not described in the current embodiment, other tightening means are contemplated by this disclosure. 
         [0048]      FIG. 5  shows the coupling device  100  prior to the tightening of the nuts  102 . The portion of the gripping ring  300  defining the slot  301  is in contact with the restraining members  251 , preventing the gripping ring  300  from radially contracting and engaging the outer surface  126  of the male piping member  125 . In  FIG. 5 , the slot  301  is in the first position (see  FIG. 15 ) and the sealing gasket  200  is not compressed. Upon tightening the nuts  102  on the tightening members  101 , the gripping ring  300  and the intermediate ring  250  will advance in the direction of the sealing gasket  200  and eventually compress it. 
         [0049]    As the nuts  102  are further tightened, additional force is transferred to the gripping ring  300 . This additional force increases the force exerted by the gripping ring  300  at the slot  301  on the restraining members  251  because the sealing gasket  200  is already compressed. Once sufficient force is applied to the restraining members  251 , at least one of the restraining members  251  deforms or dislocates from the intermediate ring  250 , which decreases the width of the slot  301  (see  FIG. 16 ), and allows the gripping ring  300  to engage the outer surface  126  of the male piping member  125  as exhibited by  FIG. 10 , which shows the tightened assembly of the coupling device  100 . It should be noted that, although  FIG. 16  shows that all of the restraining members  251  have been dislocated from the intermediate ring  250 , allowing the slot  301  to be compressed to a narrower width, the degree of compression of the slot  301  varies according to the outer diameter of the male piping member  125  in relation to the inner diameter of gripping ring  300 . Accordingly, all of the restraining members  251  need not necessarily dislocate from the intermediate ring  250  before the gripping ring  300  engages the outer surface  126  of the male piping member  125 . In various embodiments, the restraining members  251  may be located on the locking ring  350  instead of the intermediate ring  250 . The intermediate ring  250  also may optionally include a compression fin  255  (shown in  FIG. 13 ). 
         [0050]    As illustrated by  FIGS. 5 and 10 , from the initial assembly of the coupling device  100  and up to the moment of establishing a tightly sealed connection, the engagement end  130  of the male piping member  125  stays central with respect to the female piping member  150  due to the permanent contact of a front edge  128  of the engagement end  130  of the male piping member  125  with an inner surface  160  of the cone-shaped portion  154  of the female piping member  150  (see  FIG. 6 ). 
         [0051]    In addition, because of a permanent interaction between the intermediate-ring-side overlapping surface  302  of the gripping ring  300  and the overlapping surface  253  of the intermediate ring  250 , the intermediate ring  250  stays concentric with the gripping ring  300  and the female piping member  150 . This arrangement results in uniform pressure applied to the sealing gasket  200  by the intermediate ring  250 . 
         [0052]    Based on the figures and written description present in both this disclosure and those to which this disclosure claims priority, one of skill in the art would understand that the current configuration of features or elements may be interchanged, combined, or eliminated as necessary. For example, functions performed by the intermediate ring  250  in the current embodiment may be approximated by the gripping ring  300  in another embodiment, making possible the elimination of the intermediate ring  250 . This arrangement could include a modified gasket to improve the sealing engagement of the device. In another example, the restraining members  251  configured as portions of the intermediate ring  250  in the current embodiment could be configured as portions of the locking ring  350  in another embodiment. 
         [0053]    Numerous characteristics and advantages of various embodiments of the present disclosure have been set forth in the foregoing description, together with details of structure and function. Many modifications, additions, and deletions will be apparent to those skilled in the art that, especially in matters of shape, size, and arrangement of parts, without departing from the spirit and scope of the disclosure and its equivalents as set forth in the following claims. Therefore, other modifications or embodiments as may be suggested by the teachings herein are particularly reserved, especially as they fall within the breadth and scope of the claims here appended.