Abstract:
A gasket and a piping system using the gasket are disclosed. The gasket has an o-shaped body including an inner diameter and an outer diameter. The gasket further may include at least one gasket retaining bar attached to the body that bar prevents the gasket from being displaced while the spigot is being inserted into the gasket. The gasket may also include at least one restraining device attached to the body. The restraining device has at least one edge that extends beyond the inner diameter of the body of the gasket to engage the spigot.

Description:
REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority to U.S. provisional application No. 61/156,998, filed Mar. 3, 2009, entitled “Gasket for Bell Socket,” and U.S. provisional application No. 61/167,716, filed Apr. 8, 2009, entitled “Gasket for Bell Socket,” both of which are specifically and entirely incorporated herein by reference. 
     
    
     BACKGROUND  
       [0002]    1. Field of the Invention 
         [0003]    The invention is directed to gaskets and, in particularly, to gaskets for bell and spigot pipe connections. 
         [0004]    2. Background of the Invention 
         [0005]    Due to thrust forces, earth movement, and external mechanical forces exerted on pipes, the industry has focused substantial attention on the problem of maintaining connections between adjacent lengths of pipe, or pipes and fittings, after installation. The majority of the solutions can be categorized into either “push-on joints,” “mechanical joints,” or “flanged joints.” 
         [0006]    Push-on solutions are exemplified by U.S. Pat. No. 2,953,398, and account for the majority of straight-run pipe connections. In a typical configuration, a spigot end of a pipe slides into a bell end of another pipe past a tightly fitted gasket. A variation of the push-on joint is evidenced by U.S. Pat. No. 2,201,372, which employs a compression snap-ring fitted within a special lip of the bell, in order to exert pressure onto locking segments and thus drive them into the spigot, restraining the joint against thrust forces. U.S. Pat. No. 3,445,120, likewise employs a gasket with stiffening segments completely encased therein that are generally disposed such that they and the gasket may roll between a locking and a free position. As the gasket rolls under extraction forces, it is intended eventually to encounter a position in which the stiffened plane needs to compress for further rolling, in theory terminating the rolling and restraining the joint. 
         [0007]    Other examples of restrained push-on joints include U.S. Pat. Nos. 5,295,697, 5,464,228, and 5,067,75,1. The securement of the connection in such references is effected by locking segments or wedges within the gasket that engage the spigot. The locking segments possess a grove 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 the mating 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 as an axis, and exerting a radially inward pressure as the segment attempts to slide past the rib. 
         [0008]    It often takes a high degree of skill and precision to assemble pipes using the above described gaskets. Furthermore, the current trend is to make pipe with walls much thinner than the current design. Whether the pipe end is produced in a manufacturing plant or is the result of field cuts required to adjust the length of the pipe, such pipes cannot be beveled or have rounded ends. Damage to the gaskets or displacement of the gaskets is a likely outcome when inserting a spigot end of a pipe without a beveled or rounded end into the bell end of another push-on joint pipe. Therefore, it is desirable to have a gasket that is durable yet easy to assemble. 
       SUMMARY OF THE INVENTION 
       [0009]    The present invention overcomes the problems and disadvantages associated with current strategies and designs and provides new devices for assembling pipes. 
         [0010]    One embodiment of the present invention is directed to a gasket. The gasket includes an o-shaped body having an inner diameter and an outer diameter. The gasket further may include gasket retaining bars attached to or molded into the outside surface of the of the cylindrical body, which prevent the gasket from being displaced from the bell socket of one pipe upon insertion of the spigot of another pipe to complete the joining of the two pipes. 
         [0011]    The retaining bars may be molded into the outer diameter of the body of the gasket and may be evenly spaced around the circumference of the gasket. The retaining bars may be made of steel, hardened steel, or other stiffening material while the body may be made of a flexible material, such as rubber. The gasket is preferably adapted to fit into the inner diameter of a bell end of a pipe. 
         [0012]    Another embodiment of the present invention is directed to a gasket also having an o-shaped body with an inner diameter and an outer diameter. The gasket may further include inserts attached to the body, where each has at least one edge which extends beyond the inner diameter of the body. The function of these inserts are to secure the assembled joint from separation. 
         [0013]    Preferably there are three or more inserts molded into the body. Each insert may have one or more edges that extend beyond the inner diameter of the body and one edge that extends to the outer diameter of the body. The inserts may be made of steel, hardened steel, or other material harder than the material of the pipe spigot which it is intended to restrain. 
         [0014]    The gasket may also include at least one anti-over-rotation device per insert to prevent over-rotation of the inserts when axial forces on the joint are in the direction to pull the pipe spigot from a bell socket containing the gasket. The anti-over-rotation devices may be metal blocks placed adjacent to the inserts. 
         [0015]    The body may be made of a flexible material, such as rubber and the gasket may be adapted to fit into the inner diameter of a bell end of a pipe. 
         [0016]    Alternatively, there may be inserts having multiple teeth with the inserts equally spaced circumferentially about the gasket. Alternately, each insert may itself be comprised of a number of individual plates placed adjacently and in direct contact to each other and each plate may have at least one tooth. Each insert may be coupled to an outer surface of the gasket and include an end, adjacent to the outer diameter of the gasket, which is at least partially rounded. Each insert may be made of steel, hardened steel, or at least, a material harder than the pipe spigot it is intended to engage. 
         [0017]    The gasket may also include gasket retaining bars attached to the body to prevent the gasket from being displaced when the joint is assembled. The gasket retaining bars may be molded into the outer diameter of the body and evenly spaced around the circumference of the gasket. The gasket retaining bars and the inserts may be placed alternatively around the gasket. The gasket retaining bars may be made of steel or hardened steel. The inserts may be restraining devices or guiding devices. 
         [0018]    Another embodiment of the present invention is directed to a piping system. The system includes at least two pipes, each pipe having a bell end and a spigot end. The spigot end of a first pipe fits into the bell end of a second pipe. The system also includes at least one gasket adapted to fit into the bell end of a pipe and provide a seal between the spigot end of the first pipe and the bell end of the second pipe. The gasket may have an o-shaped body including an inner diameter and an outer diameter and gasket retaining bars attached to the body that prevents the gasket from being displaced during insertion of the spigot end of a pipe into the bell end of another pipe. 
         [0019]    The retaining bars may be molded into the outer diameter of the body and may be evenly spaced around the circumference of the gasket. The retaining bars may be made of steel, hardened steel, or other material harder than the body of the gasket while the body may be made of a flexible material, such as rubber. The gasket is preferably adapted to fit into the inner diameter of a bell end of a pipe. 
         [0020]    Another embodiment is also directed to a piping system. The system includes at least two pipes, each pipe having a bell end and a spigot end, wherein the spigot end of a first pipe fits into the bell end of a second pipe. The system further includes at least one gasket that is adapted to fit into the bell end of a pipe and provide a seal between the spigot end of the first pipe and the bell end of the second pipe. Each gasket has an o-shaped body including an inner diameter and an outer diameter and may include three or more inserts coupled to the body. The inserts may have at least one edge that extends beyond the inner diameter of the body and is adapted to engage an outer surface of the spigot end of the first pipe. 
         [0021]    There may be a plurality of inserts molded into the body with each insert having one edge that extends to or beyond the inner diameter of the body to engage an outer surface of the spigot end and one edge that extends beyond the outer diameter of the body to engage an inner surface of the bell end. The inserts may be made of steel, hardened steel, or other material harder than the spigot of the pipe. The system may further include anti-over-rotation devices to prevent over-rotation of the inserts during use of the gasket. The anti-over-rotation devices may be metal blocks placed adjacent to the inserts. While the body is made of a flexible material, such as rubber. 
         [0022]    Alternatively, there may be multiple inserts having a number of teeth. Each insert can also be comprised of a number of individual plates placed adjacently and in direct contact to each other, each plate having at least one tooth. The restraining devices may be coupled to an outer surface of the gasket. 
         [0023]    Each insert may include an end, adjacent to the outer diameter of the gasket, which is at least partially rounded and fits into a rounded surface on the inner diameter of the bell end. Each insert may be made of steel or hardened steel. 
         [0024]    The system may further include gasket retaining bars attached to the body to prevent the gasket from being displaced during insertion of the spigot end of a pipe into the bell end of another pipe. The gasket retaining bars may be molded into the outer diameter of the body and evenly spaced around the circumference of the gasket. The gasket retaining bars and the insert may be placed alternatively around the gasket. The gasket retaining bars may be made of steel or hardened steel. The inserts may be restraining devices or guiding devices. 
         [0025]    Other embodiments and advantages of the invention are set forth in part in the description, which follows, and in part, may be obvious from this description, or may be learned from the practice of the invention. 
     
    
     
       DESCRIPTION OF THE DRAWINGS 
         [0026]    The invention is described in greater detail by way of example only and with reference to the attached drawings, in which: 
           [0027]      FIG. 1  is a first embodiment of the invention. 
           [0028]      FIG. 2  is a second embodiment of the invention. 
           [0029]      FIGS. 3   a - c  are versions of a third embodiment of the invention. 
       
    
    
     DESCRIPTION OF THE INVENTION 
       [0030]    As embodied and broadly described herein, the disclosures herein provide detailed embodiments of the invention. However, the disclosed embodiments are merely exemplary of the invention that may be embodied in various and alternative forms. Therefore, there is no intent that specific structural and functional details should be limiting, but rather the intention is that they provide a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present invention. 
         [0031]    A problem in the art capable of being solved by the embodiments of the present invention is maintaining gasket position during pipe assembly and maintaining pipe assembly during use. It has surprisingly been discovered that inserting retaining bars into a gasket can prevent the gasket from becoming dislodged due to axial forces including those from assembly of the pipes and from internal and external hydrostatic forces. Furthermore, it has surprisingly been discovered that adding restraining inserts to the gasket may prevent the pipes from coming apart during use. 
         [0032]      FIG. 1  depicts a first embodiment of a gasket  11 . Gasket  11  sits between the spigot end  13  of pipe  12  and the bell end  15  of pipe  14 . Gasket  11  may be of any shape; however, gasket  11  is preferably cylindrical in shape, with or without grooves, ribs, or other cylindrical projections to aid in sealing. Gasket  11  may further be of any material including, but not limited to, rubber, silicone, plastic, metal, fiber, etc. Preferably, gasket  11  is of a material that allows a low insertion force to be applied to pipe  12  as it is being inserted into pipe  14 . Additionally, there may be grooves in the inner surface of gasket  11  to further reduce the necessary insertion force. However, gasket  11  is preferably resilient enough not to tear if spigot end  13  is un-beveled. Gasket  11  may provide a seal between pipe  12  and pipe  14 . The outer diameter of gasket  11  and the inner diameter of bell end  15  may be of complimentary configurations. 
         [0033]    Inner diameter of bell end  15  preferably is of a shape to encompass the upper portion of the outer diameter of gasket  11 . For instance, in the embodiment shown in  FIG. 1 , the inner diameter of bell end  15  contains a recess  17  that borders the outer diameter of gasket  11  on three sides, thereby preventing gasket  11  from sliding. 
         [0034]    Gasket  11  may be anchored in bell end  15  by mating ribs and grooves on the outer surface of gasket  11  and the inner surface of bell end  15 . Furthermore, adhesive may be used to anchor gasket  11  into position. Additionally, the outer diameter of gasket  11  may be slightly larger than the inner diameter of bell end  15  to obtain a compression fit between gasket  11  and bell end  15 . Preferably, gasket  11  may have a plurality of gasket retaining bars  16  molded into the outer surface of gasket  11 . 
         [0035]    Retaining bars  16  may extend the length of gasket  11  in the axial direction. Retaining bars  16  may securely fit into recess  17  to prevent gasket  11  from being displaced during insertion of pipe  12  into pipe  14 . Gasket  11  may be flexible to allow insertion into recess  17 . Retaining bars  16  may be of any durable, sturdy material capable of withstanding a minimum threshold of physical force. Preferably, retaining bars  16  are comprised of a material stiffer than the gasket material. The number and position of retaining bars  6  can be varied to optimize performance. 
         [0036]      FIG. 2  is an embodiment of a gasket  21  having a plurality of inserts  28 . Inserts  28  may be of any material capable of withstanding a minimum threshold of physical force. Preferably, inserts  28  are comprised of steel or hardened steel. Exposed ends  28   a  and  28   b  of inserts  28  may be hard and impact resistant enough to accept contact with spigot end  23  of pipe  22 . However, in certain embodiments, where only alignment is required, inserts  28  may be comprised of plastic or rubber. In such alignment embodiments, the inserts  28  may guide and center the spigot end  23  of pipe  22  into the bell end  25  of pipe  24 . 
         [0037]    A plurality of inserts  28  are placed in axially spaced rows in gasket  21 . Furthermore, a plurality of sets of inserts  28  may be placed circumferentially around gasket  21  at regular intervals. While any number of inserts  28  may be used, preferably at least three inserts  28  are used. Inserts  28  preferably have parallelogram cross-sectional shapes and are aligned such that the surfaces presented to the spigot end  23  of pipe  22  incline away from the throat (outermost opening of the bell end  25  of pipe  24 ). Furthermore, inserts  28  present an inclined surface to spigot end  23  upon insertion into bell end  25 . 
         [0038]    Inserts  28  may be restraining devices that prevent pipe  22  from separating from pipe  24  during use of the pipes. In such embodiments, the edges  28   a  of inserts  28  engage the bell end  25  of pipe  24  and the opposite edges  28   b  engage the spigot end  23  of pipe  22 . In certain embodiments, the inner diameter of bell end  25  may include raised ribs or depressed grooves for edges  28   a  to engage. 
         [0039]    As the spigot end  23  of pipe  22  is inserted through bell end  25  of pipe  24  and gasket  21 , the inclination of inserts  28  is increased from the original inclination. This action serves to center spigot end  23  in bell end  25  and align spigot end  23  radially within bell end  25 . An extracting action of spigot end  23 , whether by external forces such as soil movements or internal pressure, causes edges  28   a  to engage the inner diameter of bell end  25  and edges  28   b  to engage the outer diameter of spigot end  23 , thus providing axial restraint to the joint in the restraining embodiments. 
         [0040]    Over-rotation of inserts  28 , in the axial direction, and puncturing of spigot end  23  may be prevented in a variety of ways. Metal blocks  29  may be placed between the inside of bell end  25  and the first insert  28  and in-between inserts  28 . The shape of the end of inserts  28  may be such that once inserts  28  have rotated the maximum amount, further rotation is prevented by a flat spot behind edge  28   b  to prevent further penetration of edge  28   b  into spigot end  23 . Bell end  25  may be shaped such that its internal diameter contains locking elements to prevent further rotation of inserts  28 . A sufficient number of inserts  28  may be placed circumferentially around gasket  21  such that the radial force of any one insert  28  is less than the force required to penetrate spigot end  23 . Other ways of preventing puncturing spigot end  23  may include, controlling the number, length, and inclination of inserts  28 , features incorporated into the ends of inserts  28 , features incorporated into the gasket  21 , and/or selection of materials. Each of these methods could be used alone or in conjunction with one or more other methods. 
         [0041]      FIGS. 3   a - c  show another embodiment of a gasket  31  where the insert is a pivoting segment  37 . Pivoting segment  37  may be of any material capable of withstanding a minimum threshold of physical force. Preferably, pivoting segment  37  is comprised of steel, hardened steel, or any other material harder than the pipe spigot  33 . The teeth  37   a  of pivoting segment  37  may be hard and impact resistant enough to accept contact with spigot end  33  of pipe  32 . In certain embodiments pivoting segment  37  may be used solely for guiding and centering spigot end  33  of pipe  32  into bell end  35  of pipe  34 . In such embodiments, pivoting segment  37  may be of any material including, but not limited to, rubber and plastic. 
         [0042]    In certain embodiments, pivoting segment  37  may have teeth  37   a  capable of engaging the spigot end  33  of pipe  32 . Pivoting segment  37  may also have a rounded end  37   b  that fits into and is able to rotate within a complementary rounded section of the inner diameter of bell end  35  of pipe  34 . Pivoting segment  37  may have any number of teeth  37   a , preferably 2 or more. A plurality of pivoting segments  37  may be regularly spaced circumferentially around gasket  31 . Any number of pivoting segments  37  may be used, but preferably at least 3 pivoting segments  37  are used. 
         [0043]    Variations in this embodiment include using multiple single-toothed locking elements, which function by booking single-toothed elements side-to-side to function as a multi-toothed unit. Such multiple single-toothed elements can be formed more easily than a single multi-toothed element since there is no internal tooth root to be formed and sharp teeth can be achieved by a simple grinding or machining operation. The multi-toothed embodiment may be formed by any method known, for instance, cold drawing, investment casting, and machining. 
         [0044]    Pivoting segment  37  works in a similar manner to inserts  28  of the embodiment shown in  FIG. 2 . Specifically, in certain restraining embodiments, as spigot end  33  is inserted into bell end  35  through gasket  31 , pivoting segment  37  pivots toward the inner diameter of bell end  35 . An extracting action of spigot end  33  causes pivoting segment  37  to rotate away from the inner diameter of bell end  35  and causes teeth  37   a  to engage the outer surface of spigot end  33 , thus providing axial restraint to the joint. Over-rotation of pivoting segment  37  may be prevented by the structure of bell end  35 , or by other means. 
         [0045]      FIGS. 3   b  and  3   c  show a pivoting segment  37  having an over-rotation prevention device  37   c . An over-rotation prevention device  37   c  may be any shape, for instance flat (as shown in  FIG. 3   b ), convexly curved, stepped, or rounded (as shown in  FIG. 3   c ). Over-rotation prevention device  37   c  may be used to prevent over-rotation and puncturing of spigot end  33  of pipe  32 . In certain embodiments, over-rotation prevention device  37   c  may be a stepped-down surface to the back extension of pivoting segment  37  and/or may be covered by the gasket material. In such embodiments, the contact between the end of segment  37  and spigot end  33  would be cushioned, thus aiding in preventing over-rotation. 
         [0046]    In certain embodiments, as shown in  FIG. 3   a , the back  35   a  of bell end  35  may be inclined from the vertical to provide a stop for pivoting segment  37 . Inclined back  35   a  may help to prevent over-rotation. Alternately, back  35   a  may be left vertical and pivoting segment  37  may be modified to all it to bottom-out before pivoting segment  37  becomes vertical enough to penetrate spigot end  33 . 
         [0047]    In certain embodiments, a lubricant coating may be applied to the surface of a gasket. Such a lubricant may facilitate movement of the gasket over the dry pipe spigot without a bevel over the rubber portion of the gasket. Preferably the lubricant is a dry-film lubricant, such as polytetrafluoroethylene, however any lubricant known may be used, including but not limited to vegetable based lubricants, solid aliphatic alcohols, silicone-bonded graphite, waxes, etc. 
         [0048]    While the embodiments of  FIGS. 1 ,  2 , and  3   a - c  are shown and described individually, the embodiments may be joined into further embodiments in any manner. Other embodiments and uses of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. All references cited herein, including all publications, U.S. and foreign patents and patent applications, are specifically and entirely incorporated by reference. It is intended that the specification and examples be considered exemplary only with the true scope and spirit of the invention indicated by the following claims. Furthermore, the term “comprising of” includes the terms “consisting of” and “consisting essentially of.”