Patent Publication Number: US-2020290098-A1

Title: Systems and methods for cleaning a pressurized pipe

Description:
FIELD 
     The present disclosure generally relates to systems and methods for cleaning pressurized pipes. 
     BACKGROUND 
     Pressurized conduits or pipes convey fluids, both liquid and gas, in municipalities, industrial plants, and commercial installations. When originally installed, a network of pipes typically includes strategically located isolation valves or block valves, which are used to isolate certain downstream sections of the pipe for repairs, relocation, and installation of new components into the pipe. When repair or maintenance of a pipe used in a municipal water system is required, however, inoperable isolation valves may need to be replaced, and the locations of existing isolation valves may necessitate the installation of additional isolation valves. 
     A hot tapping procedure may be used during pipe repair or maintenance to minimize service disruption. In a hot tapping procedure, a new access point into the pipe is formed while the fluid inside the pipe remains at an operable pressure. For example, commonly assigned U.S. Pat. Nos. 8,627,843 and 9,644,779 disclose methods of installing additional gate valves in pressurized pipes that do not require service interruption and result in minimal fluid or pressure loss. The additional gate valves connect to the pipe as an assembly using a permanent housing known as a valve housing that is sealably clamped, welded, or otherwise sealably joined to the pipe and normally extends upward. A temporary gate valve is sealably mounted on the open top of the valve housing (i.e., the distal end of the valve housing). One or more “tap” or installation housings and a tapping machine are mounted on top (distal end) of the temporary gate valve for delivering a cutting device through the temporary gate valve to the proximal end of the valve housing to cut a hole or “coupon” in the exposed pipe. After removal of the cutting device and closure of the temporary gate valve, the same or similar installation housings are mounted on the distal end of the temporary gate valve for delivering the gate valve cartridge through the temporary gate valve and to the interior of the valve housing, where it is housed while in the open position. This procedure is accomplished without depressurizing the pipe. 
     Instead of adding a gate valve to a pipe that may remain as a permanent fixture as disclosed in the &#39;843 and &#39;779 patents, sometimes all that is desired is to stop the flow through the pipe just upstream of a repair or maintenance location without installing a gate valve. In this case, a line stop is used to temporarily isolate the pipe at or upstream of the site of the repair or maintenance, while keeping the remainder of the system in operation. Similar to the &#39;843 and &#39;779 patents, commonly assigned U.S. Pat. No. 6,810,903 discloses a system that includes the use of a line stop fitting mounted to the pipe and a temporary gate valve mounted on top of the line stop fitting. Using appropriate housings and a tapping machine mounted on top of the temporary gate valve, a cutting device is inserted through the temporary gate valve to cut an opening in the pipe. After removal of the cutting device and closure of the temporary gate valve, a pump and ram with a housing are used to insert a line stop through the temporary gate valve and line stop fitting and into the pipe temporarily (see FIGS. 1-16 of the &#39;903 patent) to stop the flow through the pipe. After a temporary line stop is withdrawn through the temporary gate valve, a completion plug is inserted through the temporary gate valve and into the line stop fitting to seal the line stop fitting so the temporary gate valve may be removed (see FIG. 16 of the &#39;903 patent). 
     In addition to maintenance and repair, piping systems may require cleaning. Over time, projections or protuberances may build up on the inside surface of the pipe, known as tuberculation. In some cases, loosely adhered solids may build up in areas where fluid velocity is low. These conditions reduce the effective cross-sectional area of the pipe, thereby increasing pressure drop through the pipe and reducing efficiency of the pipe system. Cleaning the pipe not only reduces the pressure drop and increases efficiency, but also can reduce or eliminate particulates, biofilms, and silt that may travel to the end user during system perturbations or maintenance, which may result in cloudy or smelly water. Current pipe cleaning systems and methods are performed on portions of the pipe system that have been shut down and drained, which is costly, labor intensive, and requires installation of bypass lines to provide fluid to the end user during cleaning. Other pipe cleaning methods are known in which the pressure in the pipe is reduced below the normal operating pressure, but also interrupt service to the end user during cleaning. 
     SUMMARY 
     In accordance with one aspect of the present disclosure, a system for cleaning an interior surface of a pressurized pipe includes an auxiliary housing coupled to the pressurized pipe, and a conduit extending though a conduit port formed in the auxiliary housing, the conduit including a suction end disposed inside the pressurized pipe and a discharge end disposed in a surrounding environment outside of the pipe. 
     In accordance with another aspect of the present disclosure, a method of cleaning an interior surface of a pressurized pipe includes placing a suction end of a conduit inside the pressurized pipe, with a discharge end of the conduit located in a surrounding environment outside of the pipe, wherein the surrounding environment has an ambient pressure that is less than a fluid pressure inside the pipe, and generating a suction flow through the conduit from the suction end to the discharge end by using a pressure differential between the ambient pressure and the fluid pressure. 
     In accordance with a further aspect of the present disclosure, a system for cleaning an interior surface of a pressurized pipe includes an auxiliary housing coupled to the pressurized pipe, a conduit extending though a conduit port formed in the auxiliary housing, the conduit including a suction end disposed inside the pressurized pipe and a discharge end disposed in a surrounding environment outside of the pipe, wherein the surrounding environment has an ambient pressure that is less than a fluid pressure inside the pipe to create a pressure differential causing a suction flow through the conduit from the suction end to the discharge end, a reel disposed in the auxiliary housing, wherein an intermediate section of the conduit is coiled around the reel, and a guide coupled to the conduit near the suction end of the pipe. 
     The features, functions, and advantages that have been discussed can be achieved independently in various embodiments or may be combined in yet other embodiments further details of which can be seen with reference to the following description and drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side elevation view, in cross-section, of a system for cleaning an interior surface of a pipe under pressure, according to the present disclosure. 
         FIG. 2  is an enlarged detail view of a pipe cleaning system having a scrubber. 
         FIG. 3  is a side elevation view, in partial cross-section, of an alternative embodiment of a system for cleaning an interior surface of a pipe under pressure, according to the present disclosure. 
     
    
    
     It should be understood that the drawings are not necessarily drawn to scale and that the disclosed embodiments are sometimes illustrated schematically. It is to be further appreciated that the following detailed description is merely exemplary in nature and is not intended to limit the invention or the application and uses thereof. Hence, although the present disclosure is, for convenience of explanation, depicted and described as certain illustrative embodiments, it will be appreciated that it can be implemented in various other types of embodiments and in various other systems and environments. 
     DETAILED DESCRIPTION 
     The following detailed description is of the best currently contemplated modes of carrying out the invention. The description is not to be taken in a limiting sense, but is made merely for the purpose of illustrating the general principles of the invention, since the scope of the invention is best defined by the appended claims. 
     This disclosure relates to systems and methods for cleaning an interior surface of a pipe while maintained at normal operating pressure. More specifically, solids loosely adhered to an interior surface of the pipe are removed, in part, by using the differential between the pressure inside the pipe and the ambient pressure in the environment surrounding the pipe to provide suction to a tool deployed within the pipe. 
       FIG. 1  illustrates a system  20  for cleaning an interior surface  21  of a pipe  22  containing a fluid  24  disposed at an operating pressure above an ambient pressure present in the surrounding environment  25  outside of the pipe  22 . A hot tapping procedure, such as described in the &#39;843, and &#39;779 patents cited above, may be performed on the pressurized pipe  22 , during which an auxiliary housing  26  is coupled to the pipe  22  and an access port  28  is cut into the pipe  22 . The auxiliary housing  26  includes a base  30  attached to an exterior surface of the pipe  22  and a housing section  32 . An end  34  of the auxiliary housing  26  is closed off by a top plate  36 . Prior to attaching the top plate  36 , the system  20  may be disposed in the housing section  32 . 
     The system  20  includes a conduit  40  having a suction end  42  and a discharge end  44 . The conduit  40  extends through a conduit port  46  formed in the auxiliary housing  26 , so that the suction end  42  is disposed inside the pressurized pipe  22  while the discharge end  44  is disposed in the surrounding environment  25  outside of the pipe  22 . An intermediate section  50  of the conduit  40  may be coiled around a reel  52 . A shaft  54  is coupled to and rotates with the reel  52 . The shaft  54  extends outside of the auxiliary housing  26 . Rotation of the shaft  54 , by mechanical, electrical, or other means, causes rotation of the reel  52  to increase or decrease the distance between the suction end  42  and discharge end  44  of the conduit  40 . A valve  56  may be provided near the discharge end  44  to control operation of the system  20 , as described more fully below. 
     A guide  60  is coupled to the conduit  40  to help position the suction end  42  of the conduit  40  adjacent the interior surface  21  of the pipe  22 . In the illustrated embodiment, the guide  60  includes an outer edge  62  sized to slidably engage the interior surface  21  of the pipe  22 , and an inner orifice  64  coupled to the conduit  40  near the suction end  42 . The guide  60  is attached to a point on the conduit  40  to leave a length of conduit that is sufficient for the suction end  42  to be placed adjacent the interior surface  21  of the pipe  22 . 
     In operation, the guide  60  is positioned inside the pipe  22  and advanced along the pipe  22  to a location along the interior surface  21  having loosely adhered debris  70 . In some embodiments, movement of the guide  60  is passive, where the guide  60  follows the direction of fluid flow through the pipe  22 . For systems using passive positioning, the guide  60  may have a shape that is highly responsive to the fluid flow, such as the parachute shape shown in  FIG. 1 . Alternatively, positioning of the guide  60  within the pipe may be active, as may be needed in low flow areas of the pipe or portions of pipe located upstream of the auxiliary housing  26 . For active positioning, the suction end  42  of the conduit  40  may be carried by a remotely operated vehicle. Once in position, the valve  56  may be opened so that the pressure differential between the higher operating pressure inside the pipe  22  and the lower ambient pressure in the surrounding environment  25  generates a suction flow through the conduit  40 . The suction flow dislodges the debris  70 , carries the debris  70  through the conduit  40 , and discharges the debris  70  from the discharge end  44  of the conduit  40 . 
     In some embodiments, the guide  60  may include a scrubber to improve the cleaning efficiency of the system  20 . In the embodiment shown in  FIG. 2 , a mechanical scrubber  80  is attached to the guide  60 . The mechanical scrubber  80  includes a base ring  82  rotatably coupled to the guide  60 . Scrubber arms  84  extend from the base ring  82  and are configured to engage the interior surface  21  of the pipe  22 . The scrubber arms  84  further may be shaped so that a fluid flow  86  through the pipe  22  creates a force on the arms  84  that causes the base ring  82  to rotate relative to the guide  60 . In this embodiment, the guide  60  is formed as a funnel attached to the suction end  42  of the conduit  40 , so that debris  70  dislodged by the scrubber arms  84  is caught by the guide  60  and directed into the conduit  40 . While a mechanical scrubber  80  is shown, it will be appreciated that the scrubber may generate sonic, pneumatic, or hydraulic forces that dislodge the debris  70 . 
     Once a cleaning operation is complete, the valve  56  may be closed to stop suction flow through the conduit  40 . The conduit  40 , reel  52 , and guide  60  may then be removed from the pipe  22  through the auxiliary housing  26  while the fluid  24  is maintained at the operating pressure, thereby continuously providing service to the end user. 
       FIG. 3  illustrates an alternative embodiment of a system  100  for cleaning the interior surface  21  of the pipe  22  containing the fluid  24  disposed at an operating pressure above an ambient pressure present in the surrounding environment  25  outside of the pipe  22 . In this embodiment, the system  100  includes an exterior conduit management system  102  that is positioned outside of the pipe  22  but maintains the conduit  40  at an elevated pressure. 
     In this embodiment, the suction end  42  of the conduit is  40  carried by a probe  110 . The probe  110  may include a guide  112  in fluid communication with the suction end  42  of the conduit  40  and configured to engage the interior surface  21  of the pipe  22 . The conduit  40  extends through a conduit port  114  formed in the auxiliary housing  26 . An intermediate section  120  of the conduit  40  extends from the probe  110  to the exterior conduit management system  102 . A further length of conduit  122  is coiled around a reel  124  provided within a pressurized housing  125  of the exterior conduit management system  102 . The exterior conduit management system  102  may be a stationary system, or it may be provided on a vehicle as shown in  FIG. 3 . The discharge end  44  of the conduit  40  is positioned adjacent an existing drain  126 , and may include a valve  128  for selectively controlling fluid flow through the discharge end  44 . 
     The exterior conduit management system  102  further includes an outer sheath  130  surrounding a portion of the intermediate section  120  of the conduit  40 . More specifically, the sheath  130  extends from a coupling  132  on the pressurized housing  125  to a sealed connection with the auxiliary housing  26 . The outer sheath  130 , therefore, is exposed to the pressure of the fluid  24  within the pipe  22 . That fluid is communicated through the outer sheath  130  to the pressurized housing  125 , thereby placing the reel  124  under the same pressure that is present within the pipe  22 . In operation, the pressure differential between the conduit suction end  42  (being at the elevated pressure of the fluid) and the conduit discharge end  44  (being at the lower, ambient pressure of the surrounding environment) generates a suction flow through the conduit  40 . 
     All references, including publications, patent applications, and patents, cited herein are hereby incorporated by reference. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein, is intended to illuminate the disclosed subject matter and does not pose a limitation on the scope of the claims. Any statement herein as to the nature or benefits of the exemplary embodiments is not intended to be limiting, and the appended claims should not be deemed to be limited by such statements. More generally, no language in the specification should be construed as indicating any non-claimed element as being essential to the practice of the claimed subject matter. The scope of the claims includes all modifications and equivalents of the subject matter recited therein as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the claims unless otherwise indicated herein or otherwise clearly contradicted by context. Additionally, aspects of the different embodiments can be combined with or substituted for one another. Finally, the description herein of any reference or patent, even if identified as “prior,” is not intended to constitute a concession that such reference or patent is available as prior art against the present disclosure.