Abstract:
A self-restrained pipe joint system and method of assembly to connect two lengths of pipe in a mechanical joint, which maximizes the advantages of both restrained push-on joints as well as mechanical joints, as are known commonly in the art. The invention has application to long-run pipe lengths as well as to appurtenances, including fittings and connections. The gasket contains locking members that act to restrain separation upon the instance of any force tending to separate the connected pipe lengths

Description:
REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a divisional of U.S. application Ser. No. 12/902,888, filed Oct. 12, 2010, which claims priority to U.S. Provisional Application No. 61/250,742, filed Oct. 12, 2009, both of which are hereby specifically incorporated by reference herein in their entireties. 
     
    
     TECHNICAL FIELD 
       [0002]    The present invention relates generally to the field of connections between lengths of pipe, or between pipes and fittings. More particularly, this invention is directed towards self-restrained sealing systems and methods of connecting two sections of pipe or pipe and piping appurtenances such as valves, fittings, hydrants and the like. 
       BACKGROUND 
       [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 there may be one or more fittings, which allow the pipe pieces to be joined to other components in the pipeline. The materials usually conveyed via pipelines require that pipeline conduits and joints between axially joined pieces of pipe, and between pipes and fittings, he substantially leak-proof 
         [0004]    Some applications require that the joints between pipe components are restrained in some 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, and sometimes, when earth tremors or other external events occur. A challenge is to make the assembly of the pipe joints as simple, economical, and reliable as possible. Due to this, the industry has focused substantial attention on the problem of maintaining connections between adjacent lengths of pipe after installation. The result of this attention is a variety of differing designs and approaches known in the art. The majority of these designs can be categorized into either “mechanical joints” or “push-on joints.” 
         [0005]    The term “pipe” as used herein shall be understood to include pipe sections, fittings, connections, and any other appurtenances to pipes. 
         [0006]    One of the well-known and the most common sealing systems used in the industry is referred to as a “mechanical joint” or simply as “MJ”. The bell end of one pipe has a cast flanged portion that is capable of receiving an elastomeric gasket. A male piping member (spigot end) of a second pipe is fitted with an elastomeric gasket and gland fitting. The fitting and the bell flanged portion have a plurality of apertures for receiving standard bolts. Before assembling the MJ connection, the fitting and the elastomeric gasket are placed over the spigot end of the second pipe.: pressure tight joint is formed when the spigot is axially inserted into the bell, and the fitting and the bell flanged portion are bolted together causing the fitting to compress the elastomeric gasket, thus sealing the two pipe pieces. 
         [0007]    The MJ connection enjoys wide acceptance in the industry, and is the subject of national and international Standards such as ANSI/AWWA C111/A21.11-95, which is incorporated in its entirety herein by reference. 
         [0008]    Numerous attempts have been made to improve upon the standardized mechanical joint. These attempts are almost uniformly characterized by the inclusion of an additional mechanism or attachment, creating a mechanical connection that resists separation of the pipes. 
         [0009]    Such attempts often require modification of the bell or the gland fitting (or both). Examples include designs that employ locking inserts recessed within the gland such as U.S. Pat. No. 784,400 to Howe and designs that rely upon specially modified bolts having toothed cams that both pivot on and bite into the spigot as the bolts are hooked under a modified lip of the bell and forced into grooves in the gland such as U.S. Pat. No. 1,818,493 to McWane. However, these solutions cannot be applied to the existing standardized mechanical joint bells. 
         [0010]    Further attempts employ additional restraining devices or teeth that are driven into the spigot as the gland fitting is tightened. In some cases, these devices or teeth are interposed between the gasket and the gland. In other cases, these devices or teeth are implemented in the elastomeric gasket. Included among these devices is U.S. Pat. Nos. 4,664,426 to Ueki and 7,207,606 to Owen et al. In other cases, these devices or teeth are implemented in the elastomeric gasket. This solution may be illustrated by U.S. Pat. Nos. 7,104,573 to Copeland; 7,108,289 to Holmes et al.; and 7,125,054 and 7,410,174 to Jones. However, the assembly of these modified MJ connections still involves in-field installation of the gland, gasket, bolts, and nuts, which can be time consuming. 
         [0011]    Another common method for connecting pipes together involves the insertion of the spigot end of the first pipe into an expanded end of the second pipe, where the interior profile of the second pipe has been specially fabricated to accommodate specially shaped elastomeric gaskets. The elastomeric gasket is sized to accommodate the spigot end of the male piping member to be received. This connection type is known in the pipe industry as a “push-on. joint.” In-field assembly of the push-on connection is much simpler than the assembly of the MJ connection. It does not involve any bolts and nuts and requires less time for assembly than the MJ connection. The spigot end of the male piping member is inserted into the bell end of the second pipe, thus developing a sealing arrangement between two pieces of pipe. No follower ring, stuffing box, or other compression mechanism is typically presented in the push-on joint. Additionally, the typical push-on joint does not include a restraining mechanism, though such mechanisms as tie bars, concrete thrust blocks, screws, and additional ring attachments have been employed in some cases to provide restraining performance. Advancements in the art have led to innovations and modifications of push-on joints to include restraining rings. Examples of such restrained push-on joints include U.S. Pat. Nos. 3,963,298 and 4,229,026 to Seiler 5,295,697 and 5,464,228 to Weber et at and 5,067,751 to Walworth et al. In some designs, the securement of the connection is effected by locking segments spaced uniformly around the elastomeric gasket inner perimeter. The toothed segments possess a groove that mates with an annular rib on the bell, such that the rib acts as a rocker, or cam, or, during some movements, as a wedge. During insertion of the spigot into the bell, the segments rotate on the rib, but are prevented from appreciable straight-line movement by engagement of the rib and groove. Upon experiencing counter-forces tending to effect removal of the spigot, the rib acts as a cam, both causing the segments to pivot on the rib, and exerting a radially inward pressure as the segments attempt to slide past the rib. These self-restraining gaskets, however, cannot be used with the standard bells for connection because of their specific shape and rib requirement. 
         [0012]    What is needed therefore is a self-restrained pipe joint system that may be used with standard mechanical joint bell and which may possess combined advantages of the push-on and mechanical joints, such as easy in-field assembling and disassembling. 
       SUMMARY 
       [0013]    Various embodiments of the present invention provide improved self-restrained pipe joint systems and methods that may be used with standard mechanical joint bells. In one aspect of the invention, a mechanical pipe joint system for joining a male piping member having an outer surface with an outer diameter and female piping member having a bell portion configured to receive a portion of the male piping member and defining an inner surface having a diameter greater than the outer diameter of the male piping member outer surface so as to define a sealing cavity therebetween when joined is provided. The joint system includes a retaining flange configured to be attached to the female piping member and defining a circular opening sized to accommodate the male piping member; and a restraining gasket for sealing and restraining the male piping member relative to the female piping member. The restraining gasket includes a sealing portion configured to be disposed substantially within the sealing cavity and to discourage fluid leakage between the inner surface of the female piping member opening and the outer surface of the male piping member, a flange portion configured to position the restraining gasket relative to the retaining flange, and a restraining portion comprising a plurality of circumferentially-spaced restraining segments formed from a material harder than a material of the male piping member and configured to engage the outer surface of the male piping member, a surface of the sealing cavity, and the retaining flange so as to restrain the male piping member within the female piping member as an extractive force is applied to the male member of the pipe joint system. 
         [0014]    In another aspect of the invention, a method of assembling a self-restrained pipe joint system is provided. This method includes the steps of: disposing a restraining elastomeric gasket within an opening of a female piping member; affixing a retaining flange to the end of the female piping member; and inserting a spigot end of a male piping member of the pipe joint system into the female member of the pipe joint system through a circular opening in the retaining flange. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]      FIG. 1  is a side cross-sectional exploded view of a female member of a pipe joint system, in accordance with an embodiment of the present invention, ready to be assembled 
           [0016]      FIG. 2  is a side, cross-sectional view of the assembled female member of the pipe joint system, in accordance with an embodiment of the present invention, ready to receive a male member of a pipe connection. 
           [0017]      FIG. 3  is a side cross-sectional view of the assembled pipe joint system in accordance with an embodiment of the present invention. 
           [0018]      FIG. 4  is an isometric view of an elastomeric gasket of the pipe joint system in accordance with an embodiment of the present invention. 
           [0019]      FIG. 5  is an isometric view of a restraining segment of the pipe joint system in accordance with an embodiment of the present invention. 
           [0020]      FIG. 6  is a top view of the elastomeric gasket with the restraining segments of the pipe joint system in accordance with an embodiment of the present invention. 
           [0021]      FIG. 7  is a cross-sectional view of the elastomeric gasket with the restraining segments, in accordance with an embodiment of the present invention, taken from the line C-C in  FIG. 6 . 
           [0022]      FIG. 8  is a close-up view of a detail D of the elastomeric gasket, in accordance with an embodiment of the present invention, shown in  FIG. 7 . 
           [0023]      FIG. 9  is a close-up view of a detail E of the elastomeric gasket with the restraining segments, in accordance with an embodiment of the present invention, shown in  FIG. 7 . 
           [0024]      FIG. 10  is a close-up view of a detail A of the assembled female member of a pipe joint system, in accordance with an embodiment of the present invention, shown in  FIG. 2 . 
           [0025]      FIG. 11  is a close-up view of a detail B of the assembled pipe joint system, in accordance with an embodiment of the present invention, shown in  FIG. 3 . 
       
    
    
     DETAILED DESCRIPTION 
       [0026]    Embodiments of the present invention now will be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all embodiments of the inventions are shown. Indeed, these inventions may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. Like numbers refer to like elements throughout. 
         [0027]    The pipe joint system and method of assembly embodiments of the present invention will be primarily described in conjunction with pipe joints suitable for round cross-section fluid pipelines. It should be understood, however, that the pipe joint system and method of assembly embodiments of the present invention can be used in conjunction with a variety of other applications, both in fluid pipe conduits and other types of pipelines. For example, the pipe joint system and assembly method embodiments may be utilized in conjunction with gas pipelines and other applications requiring secure, fluid tight connections between adjacent piping conduits having various cross-sectional shapes. 
         [0028]    Embodiments of the present invention are described below primarily in conjunction with a pipe joint system connecting an elongate female pipe section comprising a bell socket with a male pipe section. However, it should be understood that embodiments of the present invention may be used with a variety of fluid piping members, including adjoining male and female pipe terminal fittings and other pipe fittings having bell sockets attached thereto and configured to receive a male piping member. 
         [0029]      FIGS. 1 and 2  illustrate the side cross-sectional views of the female member  100  of a pipe joint system  10  (See  FIG. 3 ). More specifically,  FIG. 1  presents an exploded diagram of the female member  100  of a pipe joint system  10  ready to be assembled, while  FIG. 2  illustrates the assembled female member  100  of a pipe joint system  10 , ready to receive axially a male member of the pipe joint system. As illustrated in  FIGS. 1 and 2 , the female member of the pipe joint system  100  may include a female piping bell end  200 , a restraining elastomeric gasket  300 , a retaining flange  400 , and the bolts  101  and associated nuts  102 . An inner surface of the female piping bell end  200  may have a standard MJ retainer groove  201  for retaining the gasket  300 . The groove  201  defines a curvilinear surface  210 , a cylindrical surface  211 , a retainer wall  203 , and a front wall  202 . In addition, the female piping bell end has a cylindrical portion  204  that extends longitudinally from the front wall  202  parallel to the female piping axis  205  to a shoulder portion  206 . The female piping bell end  200  also may have a flange  207 , which may include a plurality of apertures  208  sized to receive the bolts  101 . 
         [0030]    As shown in  FIG. 1  the self-restrained gasket  300  may include an annular body  301  and a plurality of restraining segments  302 . Referring to  FIG. 7 , the body  301  may include a sealing portion  303 , a retaining portion  304 , and a flanged portion  305 . The sealing portion  303  of the gasket  300  may be composed of an elastomeric material so as to provide a substantially fluid tight seal between the male piping member  500  and the retaining groove  201  of the female piping bell end  200  as will be discussed in greater detail later (See  FIG. 2 ). The sealing portion  303  of the gasket  300  has inner and outer sealing surfaces  306  and  307 , respectively. The outer sealing surface  307  is configured to fit within a standard mechanical joint bell without necessitating any changes to the configuration of the female piping bell end  200  or spigot end of a male piping member  500 . The outer sealing surface  307  may have a cylindrical portion  308 . To obtain compression between the gasket  300  and the female piping bell retaining groove  201  when installed, the diameter of the gasket cylindrical portion  308  may be slightly larger than the diameter of the cylindrical surface  211  of the retaining groove  201  of the female piping bell end  200 . The flanged portion  305  of the gasket  300  provides a mechanism for securing the gasket  300  in the assembled female member of the pipe joint system  100  and restricting the movement of the gasket  300  in the direction parallel to the female piping axis  205  (See  FIG. 2 ). The retaining portion  304  of the elastomeric gasket  300  may have a cylindrical outer surface  309  and a frusto-conical surface  310 , disposed on the inner surface of the retaining portion  304 . 
         [0031]    As shown in  FIGS. 4 ,  6  and  7 , the restraining portion of the restraining elastomeric gasket  300  is composed of a plurality of circumferentially-spaced restraining segments  302  formed out of a rigid material. The restraining segments  302  can be composed of any material harder than the material of the male piping member  500 . The number of such restraining segments  302  may depend upon the expected separative forces to be encountered by the pipe joint system  10 , with a higher force tending to recommend a larger number of restraining segments  302 . Each restraining segment  302  may include two portions: a restraining portion  311  and a back or supporting portion  317  (See  FIGS. 5 and 9 ). 
         [0032]    The restraining segments  302  may be integrally molded within the gasket elastomeric body  301  so that the restraining segments  302  are at least partially embedded within the resilient elastomeric material. The restraining segments  302  are preferably either bonded to the material of the gasket elastomeric body  301  during the curing or manufacturing process, or are held in place by a suitable adhesive or by other mechanical methods. The restraining segments  302  are retained relative to each other by segments of the elastomeric material  312  extending radially between adjacent restraining segments  302  as shown in  FIG. 6 . 
         [0033]    The supporting portion  317  of the restraining segment  302  may protruded horizontally outward of the restraining portion  311 (see  FIG. 11 ). As it shown in  FIG. 6 , the supporting portion  317  of the restraining segment  302  may be embedded in the flanged portion  305  of the gasket elastomeric body  301 . 
         [0034]    In various embodiments, as shown in  FIGS. 5 ,  9 , and  11 , the restraining segment  302  possesses a plurality of teeth  313  for engaging the outer surface  501  of the male piping member  500 . The plurality of teeth  313  on the restraining segments  302  are presented to the male piping member  500  at different radial spacings to compensate for possible variations in the male piping member  500  diameter within the tolerance limits of the size of pipe to be employed. The rearward most teeth  314  on the restraining segments  302  collectively define an opening having a diameter slightly smaller than a pipe having the smallest possible diameter that could be employed in the joint. Further, the forward most teeth  315  on the restraining segments  302  may collectively define an opening having a diameter slightly smaller than a diameter of the male pipe having the largest possible diameter that is capable of being employed in the joint. One or more intermediate teeth  316  may be provided on each of the restraining segments  302 , which serve to improve the gripping force of the restraining segments  302  on the inserted male piping member  500 . With the additional teeth, the number of contact surfaces on the male pipe is increased thereby giving the restraining segments  302  the ability to create a larger footprint on the outer surface  501  of the male piping member  500 . The larger contact surface reduces stresses on the male piping member  500  at the locking members&#39; locations. 
         [0035]    The retaining flange  400  (See  FIGS. 1 and 2 ) may have a circular opening  401  to accommodate the male piping member  500 . The diameter of the opening  401  may be slightly larger than the diameter of the male piping member  500  having the largest possible diameter that is capable of being employed with the joint. The retaining flange  400  may also have two counterbores  402  and  403 . The lower counterbore  402  is bounded by a circular wall  404  leading to a frusto-conical surface between the counterbore  402  and the counterbore  403  (See  FIGS. 1 and 2 ). A lower counterbore  402  is sized to accommodate the flanged portion  305  of the restraining elastomeric gasket  300 . The diameter of the circular wall  404  of the lower counterbore  402  may be slightly larger than the outer diameter of the flanged portion  305  of the gasket  300 . An upper or retaining counterbore  403  may provide a mechanism for securing and positioning the gasket  300  in the retaining flange  400  during assembly of the female member of the pipe joint assembly  100  (See  FIGS. 2 ,  10 , and  11 ). To facilitate positioning of the gasket  300  in the flange  400 , the diameter of the circular retaining wall  406  of the retaining counterbore  403  may be slightly smaller than the diameter of the cylindrical outer surface  309  of the retaining portion  304  of the elastomeric gasket  300 . A frusto-conical surface  407  of the retaining counterbore  403  in conjunction with the circular retaining wall  406 , discourages the elastomeric gasket  300  with the restraining segments  302  from collapsing radially inward during an assembly of the female member of the pipe joint assembly  100 . As it shown in  FIG. 1 , the retaining flange  400  may include a plurality of apertures  408 . 
         [0036]    Standard MJ bell connections typically require full in-field assembly, which is time consuming and costly. Unlike these connections, the connection in accordance with various embodiments of the present invention allow pre-assembly of the female member of the pipe joint system  100  before in-field assembly of the pipe system. 
         [0037]    Referring to  FIGS. 2 and 10 ; the restraining elastomeric gasket  300  is assembled with the retaining flange  400  by inserting the retaining portion  304  of the gasket elastomeric body  301  in the retaining counterbore  403  of the retaining flange  400 . In various embodiments, the outer diameter of the retaining portion  304  of the gasket elastomeric body  301  is slightly larger than the diameter of the retaining counterbore  403  of the retaining flange  400  and the slight interference fit between the outer cylindrical surface  309  of the retaining portion  304  of the gasket elastomeric body  301  and the circular retaining wall  406  of the retaining counterbore  403  of the retaining flange  400  can aid in positioning and retaining the restraining elastomeric gasket  300  during assembly of the female member  100  of the pipe joint system  10  (See  FIG. 10 ). The interaction between the frusto-conical shaped surface  310  of the retaining portion  304  of the gasket elastomeric body  300  and the frusto-conical shaped surface  407  of the retaining counterbore  403  of the retaining flange  400  discourages collapsing of the restraining elastomeric gasket  300  radially inward. Furthering the assembly of the female member  100  of the pipe joint system  10 , the restraining elastomeric gasket  300 , pre-assembled with the retaining flange  400 , is placed within the female piping bell end  200 , such that the lower surface  409  of the retaining flange  400  engages the outer flat surface  209  of the flange  207  of the female piping bell end  200  (See  FIGS. 2 and 10 ). The retaining flange  400  is then secured in place by the bolts  101  and associated nuts  102 . Now, the female member  100  of the pipe joint system  10  is ready for the in-field installation of the pipe line system. Like the push-on pipe joint system assembly, assembly of the pipe joint system in accordance with various embodiments of the present invention only requires in-field insertion of the male piping member  500  into the pre-assembled female member  100  of the pipe joint system  10  (See  FIG. 3 ). 
         [0038]    Upon insertion of the male piping member  500  into the female piping bell end  200 , the teeth  313  of the restraining segment  302  are forced radially outward by the presence of the male piping member  500 . In various embodiments, the supporting portion  317  of the restraining segment  302  engages surface  209  of the female piping bell end  200 . As the male pipe is installed, the restraining segment  302  rotates with the supporting surface sliding into engagement with the curvilinear surface  210 . (See  FIG. 11 ). In various embodiments, the volume of compressible elastomeric material presented between the lower surface  318  of the restraining portion  311  of the segment  302  and the outer sealing surface  307  of the gasket  300  allows for such outward movement without compromising the integrity of the gasket  300 . As it shown in  FIG. 11 , even when the restraining segment  302  rotates radially outward, at least one of the teeth  313  will be in contact with the outer surface  501  of the male piping member  500 . The male piping member  500  may be advanced as in the prior art until stopped by the shoulder region  206  of the female piping bell end  200  (See  FIG. 3 ). The rotating of the restraining segments  302  combined with an interaction between the inner sealing surface  306  of the gasket elastomeric body  301 , and the male piping member outer surface  501  causes the sealing portion  303  of the gasket  300  to be compressed to form a fluid seal arrangement between the male piping member outer surface  501  and the retainer wall  203  of the retaining groove  201  of the female piping bell end  200 . The joint is now sealed and fluid under pressure can be carried by the pipe joint system  10 . 
         [0039]    As the fluid pressure rises, the male piping member  500  may be urged to move out of the female piping bell end  200  of the female member  100  of the pipe joint system  10 . To counteract this force, as the male piping member  500  tries to move out of the female piping bell end  200 , at least one of the teeth  313  digs into the outer surface  501  of the male piping member  500  as the restraining segments  302  tend to move in a direction of the retaining flange  400  such that the surface  319  engages surface  405 . This engagement will cause the restraining segment  302  to pivot inward around a point of contact between an upper surface  319  of the supporting portion  317  of the restraining segment  302  and the frusto-conical shaped surface  405  of the lower counterbore  402  of the retaining flange  400  (See  FIG. 11 ). The frusta-conical shaped surface  405  urges the restraining segments  302  to move inwardly causing even dipper digging of the teeth  313  into the outer surface  501  of the male piping member  500 . 
         [0040]    In summary, embodiments of the self-restrained pipe joint system combine the advantages of using widely popular standard mechanical joint piping bell and the simplicity of the in-field push-on joint connection assembly. 
         [0041]    Many modifications and other embodiments of the invention set forth herein will come to mind to one skilled in the art to which these invention pertain having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is to be understood that the invention is not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.