Abstract:
A locking ring-type pipe joint has a spigot ring provided on a first pipe section, a bell ring provided on a second pipe section, and a locking ring that may be contracted to engage the spigot ring to the bell ring. First and second circumferential grooves formed in the spigot ring are configured to receive a test gasket and a pipe seal gasket respectively. An annular test space between the gaskets is in closed connection with a pressure port, whereby the pressure seal of the pipe seal gasket may be evaluated after the pipe sections are joined and prior to activating the joint restraint feature, installing the next pipe, and back-filling the pipe sections.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention pertains to piping systems, and more particularly to a pipe joint which can be tested for sealing integrity during assembly of the piping system and then locked into position by mechanical means to prevent future separation of the joint.  
         BACKGROUND OF THE INVENTION  
         [0002]    Piping systems, including piping systems comprising concrete pipe, have been used to supply and dispose of water, sewage, and similar fluids. The pipe may be of steel, concrete, or other construction materials. Such piping systems are typically buried underground and may traverse many miles. Accordingly, it is important to prevent the leakage of fluids from the pipe. In many instances, fluid is pumped through the pipe, therefore the pipe may be subjected to high pressures. However, even if the fluid is not pumped, it is desirable to have leak-free pipe to avoid loss or contamination of the fluid being conveyed or contamination of areas surrounding the pipe.  
           [0003]    Piping systems are susceptible to leakage at joints when the joints are improperly assembled or adjacent sections of pipe are subjected to thrust forces that are sufficient to separate the adjacent pipe sections. These thrust forces are caused by directional changes in alignment of the pipeline, by obstructions to flow such as bulkheads or closed valves, or by changes in size of the pipe. While it is important to prevent such joint separation, it is noted that some-flexibility between adjacent pipe sections is desirable to facilitate the installation and assembly of the piping system and to accommodate minor movement of pipe sections during use. To accomplish the objective of preventing joint separation while permitting some degree of flexibility, various restrained joints have been developed. A particular type of restrained joint is disclosed in U.S. Pat. Nos. 3,177,019; 3,776,576; and 5,004,274, each assigned to the assignee of the present invention and hereby incorporated by reference in their entirety. Each of these patents disclose restrained joints wherein a steel locking ring is provided in a first pipe section and may be contracted to engage a corresponding recess formed into an adjacent pipe section. This type of pipe joint has particular advantages that facilitate the quick and efficient assembly of the joint restraining mechanism.  
           [0004]    Because piping systems for supplying and disposing of water and other fluids are typically buried beneath the ground, it is important to ensure that the pipe joints are adequately sealed prior to restraining the joint and back-filling over the buried pipe. This is particularly important when structures such as roads or buildings will be constructed above the buried pipe prior to a pressure test of the completed pipeline. Without the ability to pressure test the seal of each joint as it is installed, testing the joint seals has included the use of feeler gauges or ultrasonic devices for checking the position of the gasket and then filling the completed pipeline with water, applying pressure and watching for a drop in pressure or other evidence of leakage. This method of verifying the joint seals results in the need to find where any indicated leakage is originating, uncovering the pipe at leakage site(s), installing the necessary leak repair procedure, and re-testing the entire line. Each of these steps can be very time consuming and expensive due to the buried condition of the line.  
           [0005]    Another method of testing pipe joints has involved pressurizing an annular space in the pipe joint, adjacent the pipe sealing gasket, with air or water. To utilize this method, the pipe must be manufactured to have a closed annular space adjacent the sealing gasket, and a means to introduce a source of pressurized air or water. Advantageously, each joint may be tested prior to back-filling allowing any leakage of the joint seal to be detected and fixed prior to installation of the next pipe. This method may be used to test the joint between adjacent pipe sections from an access port located inside the pipe, when persons are permitted inside the pipe. When conditions prevent access of personnel inside the pipe, an access port coupled to the test section may be provided on the exterior of the pipe.  
           [0006]    Therefore, a need has been noted for a pipe joint that both accommodates thrust forces while also providing assurance of the pressure seal integrity of each pipe joint in a pipeline prior to activation of an efficient restraining mechanism, installation of the next piece of pipe, and burying of the pipeline.  
         SUMMARY OF THE INVENTION  
         [0007]    The present invention provides a testable restrained pipe joint for joining first and second pipe sections that permits testing of the sealing integrity of the pipe joint prior to restraining the joint, installing additional pieces of pipe and back-filling. In an exemplary embodiment, the pipe joint includes a spigot ring on the first pipe section and a bell ring on the second pipe section. The bell ring has a locking ring that can be contracted to engage the bell ring to the spigot ring. The spigot ring has two circumferential grooves formed in its exterior surface for receiving a test gasket and a pipe seal gasket, respectively. A pressure port formed in the spigot ring provides fluid access to the annular space between the test gasket and the pipe seal gasket, whereby the integrity of the joint seal may be tested by pressurizing the annular space with air or water.  
           [0008]    In one aspect of the invention, the pressure port is accessible from a location interior to the pipe joint. Accordingly, testing of pipe sections according to this embodiment may be accomplished by personnel from inside the laid pipe. This embodiment is suited for use with pipe sections having interior diameters large enough to permit personnel to enter the pipe when safety regulations permit such personnel entry.  
           [0009]    In another aspect of the invention, the pressure port is provided at a location exterior to the pipe joint. This embodiment is suited for use with pipe sections having interior diameters too small to safely accommodate personnel within the pipe. The pressure port is directly connected with the enclosed annular space between the two gaskets in the spigot ring groove.  
           [0010]    In yet another aspect of the invention, a method of testing a pipe assembly having first and second pipe sections coupled together by a spigot ring, a bell ring, and a locking ring for engaging the bell ring to the spigot ring includes coupling a pressure source to a pressure port on the spigot ring, pressurizing an annular space between gaskets on the spigot ring, and monitoring the pressure.  
           [0011]    The features and objectives of the present invention will become more readily apparent from the following Detailed Description taken in conjunction with the accompanying drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]    The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with a general description of the invention given above, and the detailed description given below, serve to explain the invention.  
         [0013]    [0013]FIG. 1 is a partial perspective view depicting a testable locking ring type pipe joint of the present invention;  
         [0014]    [0014]FIGS. 2A-2B are partial cross-sectional views of the pipe joint of FIG. 1 illustrating an externally testable joint; and  
         [0015]    [0015]FIG. 3 is a partial cross-sectional view of a pipe joint similar to that shown in FIGS. 2A-2B, and illustrating an internally testable pipe joint. 
     
    
     DETAILED DESCRIPTION  
       [0016]    Referring to FIGS. 1 and 2A, there is shown an exemplary testable pipe joint  10  of the present invention. The pipe joint  10  comprises first and second pipe sections  12 ,  14  which may be joined together at their respective ends along with other similar pipe sections to form a pipeline. The pipes  12 ,  14  are depicted herein as prestressed concrete pressure pipes having concrete cores and steel cylinders that are wound by pre-stressing steel wires, but it will be recognized that the pipe may be of other configurations and materials used for pipelines, such as steel, reinforced concrete or ductile iron. The first pipe section  12  includes a spigot ring  16  and the second pipe section  14  includes a bell ring  18  adapted to receive the spigot ring  16  of the first pipe section  12 , as disclosed in U.S. Pat. No. 5,004,274, herein incorporated by reference in its entirety. The spigot ring has an exterior surface  20  and an interior surface  22  (shown in FIG. 2A). First and second circumferential grooves  24 ,  26  are formed in the exterior surface  20  of the spigot ring  16  proximate the distal end of the spigot ring  16  and are configured to receive annular, o-ring type gaskets as disclosed in U.S. Pat. No. 5,004,274. Spigot ring  16  further includes a reduced diameter area  28  formed in the exterior surface  20  inboard of the distal end of the spigot ring  16  and behind the first and second circumferential grooves  24 ,  26 . In the exemplary embodiment shown in FIG. 1, the first pipe section  12  further includes a plug  32  for sealing a pressure port that facilitates testing the assembled pipe joint  10 , as will be discussed in more detail below. A pocket  34  is formed into an outer mortar coating  96   a  of the first pipe  12  to permit access to the plug  32  when setting up to test the assembled pipe joint  10 .  
         [0017]    With continued reference to FIGS. 1 and 2A, the bell ring  18  provided on the second pipe section  14  includes a flared distal end  40  which is sized to slide over the spigot ring  16  on the first pipe section  12  to form the pipe joint  10 . The bell ring  18  includes a locking ring  42  which is split to permit expansion or contraction of the locking ring  42 , as described in U.S. Pat. No. 5,004,274. Spaced first and second opposing ends  44 ,  46  of the locking ring  42  are surrounded by a clip  48  that facilitates engagement of the spigot ring  16  within the bell ring  18  without damaging gaskets  82 ,  84  which are fitted on the spigot ring  16 . The spacing between the first and second opposed ends  44 ,  46  of the locking ring  42  may be adjusted by a bolt and U-nut assembly  50 ,  56  to expand or contract the locking ring  42 . Locking ring assembly  42  includes a first lug  52  provided on the first end  44  of the locking ring  42  and a second lug  54  provided on the second end  46  of the locking ring  42 . The first and second lugs  52 ,  54  are coupled by a fastener  56  whereby tightening of the fastener  56  reduces the space between the first and second ends  44 ,  46  to thereby contract the locking ring  42 . Advantageously, the locking ring  42  and the thin metal clip  48  permit the bell ring  18  to slide over the gaskets  82 ,  84  in the spigot ring  16  when the locking ring  42  is in an expanded state, whereafter the fastener  56  may be tightened to place locking ring  42  in a contracted state to engage the spigot ring  16  about the reduced diameter area  28 .  
         [0018]    Prior to assembly of the pipe joint  10 , a test gasket  82  is fitted into the first circumferential groove  24  and a pipe seal gasket  84  is fitted into the second circumferential groove  26 . As the spigot ring  16  is inserted into the bell ring  18 , the test gasket  82  and pipe seal gasket  84  are compressed against the interior surface  60  of the bell ring  18  to thereby seal the pipe joint  10 . Advantageously, the two gaskets  82 ,  84  create an annular joint test area between the first and second circumferential grooves  24 ,  26  whereby the integrity of the pipe seal gasket  84  may be tested, as will be discussed below. The test gasket  82  completes the seal of the annular test section with respect to the exterior of the pipe sections  12 ,  14  and may be formed from the same material as pipe seal gasket  84 . The test gasket  82  is only needed to test the integrity of the pipe joint  10  during initial assembly, whereafter sealing of the pipe joint is accommodated by the pipe seal gasket  84 . Accordingly, the test gasket  82  may alternatively be formed from material other than that used for pipe seal gasket  84 , including material adapted to disintegrate or dissolve after installation is complete.  
         [0019]    The construction of the first and second pipe sections  12 ,  14  as pieces of prestressed concrete cylinder pipe is illustrated more clearly in FIG. 2A wherein the pipe sections include concrete cores  90   a ,  90   b , steel cylinders  92   a ,  92   b  wound by pre-stressed steel wires  94   a ,  94   b  and outer mortar coatings  96   a ,  96   b . Locking ring  42  is disposed within a circumferential groove  62  formed in the interior surface  60  of bell ring  18 . As shown in FIG. 1, bell ring  18  further includes holes  58  spaced circumferentially around the end of the bell ring  40  to permit grout to be placed within the assembled joint  10  after the locking ring  42  has been contracted to engage the spigot ring  16 .  
         [0020]    Referring now to FIG. 2A, the fully assembled joint  10  is shown in more detail. Spigot ring  16  has been inserted within the interior of bell ring  18  and locking ring  42  is shown in the contracted state to engage reduced diameter area  28  of the spigot ring  16 . A pressure port  70  is formed into a second end  72  of the spigot ring  16 , opposite the distal end containing the first and second grooves  24 ,  26 . The pressure port  70  is in fluid communication with the first and second circumferential grooves  24 ,  26  via a conduit  76  disposed between the pressure port  70  and the circumferential grooves  24 ,  26 . In the exemplary embodiment shown, the conduit  76  comprises a steel channel section  78  extending axially along the inner surface  22  of the spigot ring  16 . An aperture  80  is formed into the spigot ring  16  adjacent to the first circumferential groove  24  to connect the conduit  76  to the annular test section between the two gaskets  82 ,  84 .  
         [0021]    With reference to FIGS. 2A and 2B, use of the testable pipe joint  10  will now be described to test pipe seal gasket  84 . To test the integrity of the pipe joint  10 , the plug  32  and its sealing gasket  32   a  are removed from the pressure port  70  and replaced with a test fitting  100 . The test fitting  100  is connected to a source of pressurized air or water  102 . Once the fitting  100  has been secured to the spigot ring  16  at pressure port  70 , pressurized air or water may be forced into the annular test space between the two gaskets  82 ,  84  through the conduit  76  and aperture  80 . Once a desired pressure has been obtained, a valve  104 , disposed between port  70  and the pressure source  102 , is closed and the pressure monitored with a pressure gauge  106  to ensure adequate sealing of the pipe joint  10  by the pipe seal gasket  84 . If the joint  10  is determined to be adequately sealed, the air or water used to pressurize the first circumferential groove  24  may be evacuated and the seal plug  32  with its sealing gasket  32   a  reinstalled in pressure port  70 . Thereafter, cement grout (not shown) may be used to encase the exposed exterior surfaces of the joint as known in the art. The exemplary embodiment described above provides an externally testable joint  10  which may be utilized to quickly and efficiently test the pressure seal of an assembled pipe joint  10  from a location external to the pipe sections  12 ,  14 . This is advantageous when access to the interior of the pipe by personnel is hindered due to the small interior diameter of the pipe or by safety regulations.  
         [0022]    Referring now to FIG. 3, there is shown another exemplary embodiment of a pipe joint  10   a  similar to that shown in FIGS. 2A-2B, but having a pressure port which is accessible from the interior of the pipe. Such a configuration is useful when access by personnel to the interior of the pipe is allowed. In the exemplary embodiment shown, like components of the first and second pipe sections  12   a ,  14  have been similarly numbered. In this embodiment, the aperture  80   a  includes internal threads whereby the aperture  80   a  may serve as an internal pressure port. Accordingly, the need for the conduit shown in FIGS. 2A-2B is eliminated. The first pipe section  12   a  further includes a recess  108  formed into the concrete core  90   a  or other lining of the spigot  22  to permit access to the internal pressure port  80   a . To test the pipe joint  10   a , a seal plug  32  and its sealing gasket  32   a  are removed from the pressure port  80   a  and a test fitting  100  is installed as described above. The annular test section between the two gaskets  82 ,  84  may then be filled with pressurized air or water to test the joint  10   a , as described above.  
         [0023]    While the present invention has been illustrated by the description of the various embodiments thereof, and while the embodiments have been described in considerable detail, it is not intended to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. The invention in its broader aspects is therefore not limited to the specific details, representative apparatus and methods and illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the scope or spirit of the general inventive concept.