Patent Document

FIELD 
   Embodiments of the invention generally relate to inflatable plugs for conduits. 
   BACKGROUND 
   Inflatable plugs are used for plugging conduits, such as sewer lines, gas lines, or oil pipelines, to permit maintenance, facilitate toxic waste containment, or remove blockages. Such plugs couple to fluid lines to facilitate inflation and deflation within conduits. 
   SUMMARY 
   The following summary sets forth certain exemplary embodiments of the invention. It does not set forth all such embodiments and is not limiting of embodiments of the invention. 
   In one embodiment, an inflatable plug insertable into a conduit and inflatable therein to restrict fluid flow comprises a bladder having an interior surface and an exterior surface and at least one fabric layer covering at least a portion of the exterior surface of the bladder. The inflatable plug also comprises a first plate, a second plate, and at least one fluid port. The first plate is positioned inside the bladder, adjacent to the interior surface of the bladder. The second plate is positioned outside the bladder, adjacent to the at least one fabric layer. The second plate is coupled to the first plate such that the first plate and the second plate clamp a portion of the at least one fabric layer and a portion of the bladder therebetween. The at least one fluid port extends through the first plate and the second plate and facilitates inflation and deflation of the bladder. 
   In another embodiment, a method of assembling an inflatable plug, which is insertable into a conduit and inflatable therein to restrict fluid flow, comprises positioning a bladder material having an outer surface on top of a first plate, and covering the outer surface of the bladder material with at least one fabric material. The method also includes positioning a second plate on top of the at least one fabric layer, coupling the first plate to the second plate, and forming a closed bladder using at least the bladder material. 
   Various embodiments herein can allow higher operating pressures than existing plugs. Additionally, embodiments herein can be configured for inflation and deflation on an end or on a side of a plug, for example. 
   Other aspects of the invention will become apparent by consideration of the detailed description and accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  shows a system according to an embodiment of the invention. 
       FIG. 2  shows a top view of an inflatable plug having a flange according to an embodiment of the invention. 
       FIG. 3  shows a partial cross-sectional view of the inflatable plug of  FIG. 2 . 
       FIG. 4  shows an exploded side view of a portion of the inflatable plug of  FIG. 2 . 
       FIG. 5  shows a system according to another embodiment of the invention. 
       FIG. 6  shows an end view of an inflatable plug having a flange according to another embodiment of the invention. 
       FIG. 7  shows a partial cross-sectional view of the inflatable plug of  FIG. 6 . 
   

   DETAILED DESCRIPTION 
   Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein are for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless specified or limited otherwise, the terms “mounted,” “connected,” “supported,” and “coupled” and variations thereof are used broadly and encompass both direct and indirect mountings, connections, supports, and couplings. Further, “connected” and “coupled” are not restricted to physical or mechanical connections or couplings. 
   Embodiments of the invention relate to inflatable plugs. While deflated, a plug is insertable into a conduit, such as a sewer line, an oil pipeline, a gas line, or a water main, through a hot tap in the conduit. Once inserted, the plug is inflated to restrict fluid flow through the conduit. Restricting fluid flow permits repair and/or maintenance (e.g., cleaning, patching holes, etc.) to be performed on the conduit. In various embodiments, a flange is positioned on the plug and configured to couple with fluid lines for inflation and deflation of the plug. 
   Embodiments of the inflatable plugs described below are adaptable to have inflation diameters between about 4 inches and 120 inches and are capable of an inflation pressure up to about 150 pounds per square inch gauge (psig). Additional inflation diameters and pressures may be achieved by adjusting various components of the plugs. Plug lengths may also be adjusted depending on the application. 
     FIG. 1  shows a system  100  according to an embodiment of the invention. The system  100  includes an inflatable plug  110 , a tube  115 , a packing seal  120 , a launch cylinder  125 , a valve  130 , and a tapping saddle  135 . The system  100  is configured for use in a conduit  105 . In the illustrated embodiment, the plug  110  is inflated to restrict fluid flow through the conduit  105 . 
   The tapping saddle  135  couples to the conduit  105  by bolts, welding, or electro-fusion. The valve  130  (e.g., a full port valve) is coupled to the tapping saddle  135  to allow selective access through the tapping saddle  135  to an interior of the conduit  105  through a hole (e.g., hot tap) formed thereon. The launch cylinder  125  couples to the valve  130  and guides the tube  115  (e.g., an inflation ram) and the deflated plug  110  into the interior of the conduit  105 . The packing seal  120  is positioned around the tube  115  to prevent any fluid in the conduit  105  from leaking out through the launch cylinder  125 . 
   The tube  115  is coupled to and in fluid communication with the plug  110  via a flange  140 . The flange  140  is positioned on a side of the plug  110  and couples to the tube  115  to facilitate fluid flow into and out of the plug  110 . The flange  140  may be constructed of, for example, metals, ceramics, or high-density plastics. Fluid entering the plug  110  may be, for example, air, nitrogen, water, or other liquids and gases suitable for inflation of the plug  110 . The fluid may also be drawn from the plug  110  and through the flange  140  to allow for deflation of the plug  110 . 
     FIG. 2  shows a top view of an inflatable plug  200  having a flange  205  according to an embodiment of the invention. The plug  200  and the flange  205  are one implementation of the plug  110  and the flange  140  of  FIG. 1 . The plug  200  is generally cylindrical and includes an inner bladder  330  (see  FIGS. 3 and 4 ), a plurality of fabric layers  210 ,  315 ,  325  (see  FIGS. 3 and 4 ), and a plurality of outer straps  220 . In the illustrated embodiment, the plug  200  includes eight outer straps  220  spaced apart and positioned adjacent an outermost fabric layer  210 . As shown in  FIG. 2 , the outer straps  220  are positioned on an exterior surface of the outermost fabric layer  210 ; however, in other embodiments, the outer straps  220  may be positioned between the outermost fabric layer  210  and an inner fabric layer  315 . The outer straps  220  circumferentially surround the plug  200  and increase the sealing capabilities of the plug  200 . The outer straps  220  may be constructed of, for example, low durometer butyl rubber, Buna-N rubber, or ballistic nylon. In some embodiments, the outer straps  220  may have a relatively high coefficient of friction to resist sliding of the inflated plug  200  within the conduit  105 . 
   The flange  205  is positioned on a side of the plug  200  and includes a top plate  225  and a bottom plate  310  (see  FIG. 3 ) coupled to the top plate  225  via fasteners  250  (e.g., bolts, screws, nails, etc.). The fasteners  250  are positioned along a circumference of the top plate  225  and extend through the top plate  225 , through the fabric layers  210 ,  315 ,  325  and the bladder  330 , to the bottom plate  310 . In the illustrated embodiment, the top and bottom plates  225 ,  310  are circular in shape and positioned such that the bottom plate  310  is aligned with the top plate  225 . In other embodiments, the top and bottom plates  225 ,  310  may be other shapes (e.g., square, octagonal, etc.), and/or may not be aligned with each other. 
   The flange  205  includes a water port  240  and an air port  235 . In the illustrated embodiment, the water port  240  is positioned in the center of the flange  205 , and the air port  235  is positioned near an edge of the flange  205 . It should be apparent to one skilled in the art that the positions of the ports  235 ,  240  may be exchanged or the positions may be modified to other suitable locations on the flange  205 . Additionally or alternatively, fewer or more ports may be provided to allow fluid flow or to support additional internal or external instrumentation (e.g., sensors, transducers, detectors, etc.) for plug monitoring. 
   The water port  240  provides fluid access to an interior region of the plug  200 . In the embodiment illustrated in  FIGS. 2 and 3 , the water port  240  is defined by the top plate  225  and the bottom plate  310 . Water or other liquids move (e.g., flow) through the water port  240  to inflate and deflate the plug  200 . In some embodiments, the water port  240  may include a ball valve with a cam and groove coupling to facilitate connection of a water line to the water port  240 . 
   The air port  235  also provides fluid access to an interior region of the plug  200 . In the embodiment illustrated in  FIGS. 2 and 3 , the air port  235  is defined by the top plate  225  and the bottom plate  310 . Air, nitrogen, or other gases flow through the air port  235  to inflate and deflate the plug  200 . In some embodiments, the air port  235  may include a ball valve with a quick connect/disconnect coupling to facilitate connection of an air line to the air port  235 . 
   In some embodiments, air, not water, is used to initially inflate the plug  200  when the plug  200  is being positioned. As such, the position of the plug  200  may be adjusted more easily within the conduit  105 . Water is then injected into the plug  200 , exhausting the air through the air port  235  and preventing potential shifting of the plug  200  within the conduit  105 . 
   The flange  205  also includes four bores  255  located radially inward of the fasteners  250 . The bores  255  are positioned about the water port  240  to facilitate coupling of the tube  115  to the flange  205 . For example, the tube may include a bracket  400  (see  FIG. 4 ) having corresponding bores. The bores  255  of the flange  205  and the bores of the bracket  400  may receive fasteners  420  to secure the tube  115  to the flange  205 . In the illustrated embodiment, the bores  255  are positioned to couple the bracket  400  and the tube  115  around only the water port  240 . In other embodiments, the bores  255  may be positioned to couple the bracket  400  and the tube  115  around both the water port  240  and the air port  235  or around only the air port  235 . 
   A cushion  230  (e.g., a polyurethane cushion or other suitable cushion) is positioned between the outermost fabric layer  210  and the top plate  225 . The cushion  230  is generally a shape similar to the top plate  225 . During assembly of the top plate  225  on the plug  200 , the cushion  230  compresses and deforms and may extend slightly past an edge of the top plate  225 , as shown in  FIG. 2 . In some embodiments, a second cushion  405  (see  FIG. 4 ) is positioned between the bladder  330  and the bottom plate  310 . The cushions  230 ,  405  prevent the top and bottom plates  225 ,  310  from creating stress lines or tears in the bladder  330  and the fabric layers  210 ,  315 ,  325 . 
     FIG. 3  shows a partial cross-sectional view of the plug  200 . In the illustrated embodiment, the plug  200  includes the bladder  330 , two inner fabric layers  315 ,  325 , a webbing  320 , and the outermost fabric layer  210 . The bladder  330  is the innermost layer and defines the interior region of the plug  200 . The fabric layers  210 ,  315 ,  325  surround and enclose the bladder  330 , protecting the bladder  330  from puncturing or tearing. The bladder  330  may be constructed of, for example, a polyurethane or other impermeable material; the inner fabric layers  315 ,  325  may be constructed of a ballistic strength nylon material or Kevlar® (available from DuPont Advanced Fiber Systems of Richmond, Va.); and the outermost fabric layer  210  may be constructed of a ballistic strength nitrile-coated nylon material. 
   The webbing  320  (which may also be constructed of a ballistic strength nylon material) is positioned between one of the inner fabric layers  315  and the outermost fabric layer  210  to increase the strength of the plug  200 . The webbing  320  extends circumferentially and lengthwise along the plug  200 , culminating at each end of the plug  200 . In some embodiments, a fabric patch (e.g., a square of webbing material) may be positioned at each end of the plug  200  such that the webbing  320  may couple to the fabric patch. Additionally or alternatively, more or fewer fabric layers  210 ,  315 ,  325  and/or webbings  320  may be used to adjust the strength of the plug  200 . 
   As shown in  FIG. 3 , a water tube  305  extends from the water port  240  into the plug  200  and an air tube  300  extends from the air port  235  into the plug  200 . The water tube  305  includes a weight  340  coupled to an end opposite from the water port  240 , such that the water tube  305  sinks and fills the plug  200  with water from a bottom of the plug  200 . The air tube  300  includes a float  335  coupled to an end opposite the air port  235 , such that the air tube  300  floats on the water and exhausts only air from the plug  200 . Additionally, the air tube  300  may include a pressure gauge to measure the inflation pressure of the plug  200 . 
     FIG. 4  shows an exploded side view of a portion of the plug  200 . Assembly of the plug  200  is performed by positioning the bladder  330  over the bottom plate  310  and the second cushion  405 . The bladder  330  is covered with the two inner fabric layers  315 ,  325 , the webbing  320 , and the outermost fabric layer  210 . The top plate  225  and the cushion  230  are positioned on the outermost fabric layer  210 , aligned with the bottom plate  310  and the second cushion  405 . 
   The fasteners  250  pass through the top plate  225 , the cushions  230 ,  405 , the fabric layers  210 ,  315 ,  325 , the bladder  330 , and the bottom plate  310  to couple the top plate  225  and the bottom plate  310 . The fasteners  250  are tightened (e.g., torqued) to compress the cushions  230 ,  405  and the fabric layers  210 ,  315 ,  325 . 
   The air port  235  and the water port  240  are also provided through the top plate  225 , the cushions  230 ,  405 , the fabric layers  210 ,  315 ,  325 , the bladder  330 , and the bottom plate  310  to allow fluid communication between an exterior of the plug  200  and the interior region. In the embodiment illustrated in  FIG. 4 , the air port  235  is provided generally at line  415 , and the water port  240  is provided generally at line  410 . In some embodiments, instrumentation and/or fittings, such as ball valves, may be inserted through the plug layers to define the air port  235  and the water port  240 . 
   The fasteners  420  pass through the bracket  400  of the tube  115 , the top plate  225 , the cushions  230 ,  405 , the fabric layers  210 ,  315 ,  325 , the bladder  330 , and the bottom plate  310  to couple the tube  115  to the flange  205 . Similar to the fasteners  250  discussed above, the fasteners  420  may be tightened to further compress the cushions  230 ,  405  and the fabric layers  210 ,  315 ,  325 . 
   In some embodiments, the bladder  330 , the fabric layers  210 ,  315 ,  325 , and the cushions  230 ,  405  may include prior-made slits or cut-outs to facilitate passing of the fasteners  250 ,  420  and/or fittings defining the air port  235  and the water port  240  between the top plate  225  and the bottom plate  310 . 
   After the flange  205  is secured, edges of the bladder  330  are sewn together to form a closed bladder. Likewise, edges of the fabric layers  210 ,  315 ,  325  are sewn together to surround the bladder  330  to form the plug  200 . A sealant (e.g., silicone, polyurethane gel, etc.) is applied to seams formed during sewing to prevent fluid leakage therethrough. In some embodiments, single pieces of the bladder  330  and the fabric layers  210 ,  315 ,  325  are used to form the plug  200 . In other embodiments, multiple pieces of bladder material and/or fabric material are sewn together to form the plug  200 . In addition, multiple stitches may be used to increase the strength of the plug  200 . 
     FIG. 5  shows a system  500  according to another embodiment of the invention. The system  500  includes an inflatable plug  510 , an air hose  515 , a water hose  525 , an air valve  520 , and a water valve  530 . The system  500  is configured for use in a conduit  505 , and the plug  510  is insertable into the conduit  505  in a similar manner to that discussed with reference to  FIG. 1 . However, in this embodiment, the plug  510  is positioned in the conduit  505  upstream from a hole through which the plug  510  is inserted. A valve  535  (e.g., a butterfly valve) is positioned in the conduit  505  downstream from the hole to prevent backflow in the conduit  505  from contacting the air and water hoses  515 ,  525 . 
   The air hose  515  and the water hose  525  are coupled to and in fluid communication with the plug  510  via a flange  540 . In the illustrated embodiment, the flange  540  is positioned on an end of the plug  510  and couples to the air hose  515  and the water hose  525  to facilitate fluid flow into and out of the plug  510 . The air hose  515  extends from the flange  540  and couples to the air valve  520  (e.g., a ball valve with quick connect/disconnect couplings), and the water hose  525  extends from the flange  540  and couples to the water valve  530  (e.g., a ball valve with cam and groove couplings). The air valve  520  couples to an air line  545  which provides air, nitrogen, or other gases through the air hose  515  toward the plug  510 . The water valve  530  couples to a water line  550  which provides water or other fluids through the water hose  525  toward the plug  510 . 
   In some embodiments, the water hose  525  may be a suction hose, and the water line  550  may be a suction line. In such embodiments, the plug  510  is filled with fluid only through the air hose  515 , and the fluid is discharged from the plug  510  through the suction hose  525 . In addition, in some embodiments, the flange  540  may include anchor lugs to facilitate movement (e.g., dragging) of the inflated plug  510 . 
   A second flange  555  is secured to an end of the plug  510  opposite from the flange  540 . The second flange  555  includes anchor lugs  560  to facilitate movement of the inflated plug  510 . In some embodiments, the second flange  555  may include fluid ports such that the plug  510  may be inflated and deflated at either end. 
     FIG. 6  shows an end view of an inflatable plug  600  having a flange  605  according to another embodiment of the invention. The plug  600  and the flange  605  are one implementation of the plug  510  and the flange  540  of  FIG. 5 . In addition, the plug  600  is generally the same in structure and function as the inflatable plug  200  discussed with reference to  FIGS. 2-4 , and like parts have been given the same reference numerals. 
   The flange  605  is positioned on an end of the plug  600  and includes a top plate  610  and a bottom plate  700  (see  FIG. 7 ) coupled to the top plate  610  via fasteners  615  (e.g., bolts, screws, nails, etc.). The fasteners  615  are positioned along a circumference of the top plate  610  and extend through the top plate  610  to the bottom plate  700 . In the illustrated embodiment, some of the fasteners  615  include an eye hole  620 . The eye holes  620  facilitate movement and/or anchoring of the plug  600  within the conduit  505 . 
   The flange  605  includes a water port  630  and an air port  625  similar to the water port  240  and the air port  235  discussed with reference to  FIG. 2 . In the illustrated embodiment, the water port  630  and the air port  625  are positioned on radially opposite sides of the flange  605 . 
     FIG. 7  shows a partial cross-sectional view of the inflatable plug  600 . As discussed above with reference to  FIGS. 2-4 , the plug  600  includes the bladder  330 , the inner fabric layers  315 ,  325 , the webbing  320 , the outermost fabric layer  210 , and the outer straps  220 , similar to the inflatable plug  200 . 
   In addition, the plug  600  includes an air tube  705  with a float  715  and a water tube  710  with a weight  720 . The air tube  705 , the water tube  710 , the float  715 , and the weight  720  function in a similar manner to the air tube  300 , the water tube  305 , the float  335 , and the weight  340  of the plug  200  discussed above with reference to  FIG. 3 . 
   In some embodiments, an inflatable plug may include a flange positioned on an edge and a flange positioned on an end. As such, a single plug may be positioned in a conduit adjacent to a hot tap in one scenario and upstream from the hot tap in another scenario. The flange may also be off center for inflation and deflation near a conduit invert or on a portion of the outer surface of the plug. 
   In other embodiments, an inflatable plug may be a non-cylindrical shape. For example, the plug may be spherical or conical to correspond with the shape of a conduit. 
   Embodiments described above allow for higher inflation pressures and are more flexible than existing molded rubber plugs. Embodiments also allow for easier positioning and insertion of plugs through hot taps and restricted access into conduits. 
   Furthermore, in various embodiments, bunching or swaging of material is not required to couple a flange on a plug, making the plug material less susceptible to failure than existing plugs with swaged collars. 
   Embodiments herein also allow for inflation and deflation on an end or on a side of a plug. In embodiments where a flange is positioned on the side of the plug, the plug does not need to navigate a bend for hot tap insertion and, therefore, does not require an inflation swivel. In addition, a shorter inflation ram and launch cylinder may be used to guide the plug. 
   Various features and advantages of the invention are set forth in the following claims.

Technology Category: 2