Abstract:
A method for curing a resin contained in a liner of an underground pipe or passageway by use of a mobile magnetron module. The module navigates the length of the passageway of pipe via air pressure which also keeps the liner inflated. A winch attached to the module regulates the rate at which the module traverses the passageway or pipe. As the module makes its way through the passageway or pipe, the magnetron emits microwaves which cures the resin. Additionally, a thermal imaging camera can be utilized in the module or trailing the module to monitor the status of the curing of the resin in its entirety.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a divisional of U.S. patent application Ser. No. 12/983,983 filed Jan. 4, 2011, which application is incorporated by reference herein. 
    
    
     BACKGROUND 
     This invention generally relates to the lining of passageways and pipelines. It is well known in the art to line an existing underground pipe or passageway by introducing a flexible tubular liner into the pipe at one end. Typically, the liner includes a portion that is impermeable to fluid and a portion that includes a curable resin. The liner is placed into one end of the pipe and anchored at that end. The liner then progresses via an eversion process throughout the interior of the pipe or is pulled in by a winch. The liner is, therefore, turned inside out as it makes its way through the pipe. The liner can also be coated on both sides of the resin impregnated fabric. 
     The means to evert the liner is typically fluid pressure produced by partially filling the everted liner in the passageway with a liquid. Curing of the resin is the chemical reaction which is accelerated by an elevated temperature. When liquid is used, the resin is cured by supplying the liquid at a controlled temperature which is sufficient to set the resin. The fluid pressure of the heated liquid is maintained in the pipe until the resin has properly cured. After curing, the existing pipe is sealed by the new liner which will have repaired cracks or other damage to the original pipe or previous liner. Typically, the lined pipe is equal to or greater in strength that the original pipe. 
     One of the deficiencies in the prior art associated with cured in place pipes is that the cure process requires refrigeration of the liner prior to installation to extend the pot life of the resin so that the resin does not prematurely set prior to installation in the pipe. Additionally, the resins compatible with the methods of the prior art may necessitate a resin possessing a long cure time. As such, the prior art methods consume large amounts of resources and energy in the refrigeration of the resin as well as the curing of the resin through water or by the use of a combination of steam and air and sometimes by the use of ultraviolet light. Furthermore, monitoring the progress of the curing process is difficult, which leads to inefficient use of materials and labor. Additionally, under-cured or incomplete cure of the resin can lead to lifts or compromised physical properties of the resin and liner. 
     It is therefore an object of the present invention to provide a method which cures the liner by means of using microwave energy to deposit thermal energy into the resin to speed up the curing process. 
     It is another object of the present invention to provide a method for monitoring the temperature of the resin in the liner so as to monitor the cure process along the entire periphery and length of the pipe liner. 
     It is another object of the present invention to provide a liner fabric which cures in an accelerated manner due to the microwave sensitivity of the fabric. 
     It is yet another object of the present invention to add a shielding layer to the fabric tube to prevent the microwave energy from escaping the tube during the cure process where the pipe being repaired is non-metallic or covered with dirt or other shielding materials. 
     It is yet another object of the present invention to provide a method for lining pipes which does not necessarily require refrigeration of the liner prior to installation. 
     SUMMARY OF THE INVENTION 
     The present invention utilizes a movable module in a passageway or pipe to cure a resin contained in the fabric liner of a pipe which may or may not contain fiberglass. The module can be used in conjunction with the known processes of lining a passageway or pipe by either the eversion process or a pull-in liner using a winch and cable. With the latter process, the liner usually has an impermeable coating on both sides. After the liner is placed in the passageway or pipe, the liner remains pushed up against the sides of the pipe by a fluid pressure, preferably air pressure. 
     The movable module may contain a magnetron which emits microwave radiation. Preferably, the microwave energy emitted by the magnetron is contained in the module, although in small pipes the magnetron may be located at the surface and transmit the energy through a microwave coax or waveguide. In addition to the magnetron, the module preferably contains a camera capable of monitoring the temperature of the resin and thus monitor the cure process of the resin; however, the camera can be separate from the module and trail or proceed the module in the passageway or pipe. The camera can be a thermal imaging camera. The module can be what is commonly known as a pipeline pig or contain wheels. The module can be attached to a cable and a power supply, or a cable constructed to accomplish both needs. The cable is also attached to a winch. 
     The movable module is lowered into one end of the liner that has been everted into the passageway or pipe. Air pressure is then used to push the module toward the second end; however, the cable remains taut and controls forward movement of the module. With the pipe liner inflated and kept at a predetermined pressure, the module will move a predetermined distance then stop for a period of approximately thirty seconds, at which time a switch activates the magnetron. A secondary device which monitors and controls the switch can be regulated by another switch that monitors horizontal position of the module. This switch can be over-ridden in the case of vertical pipeline applications. The magnetron then begins to emit radiation within the liner which starts the cure process of the resin. The camera monitors the progression of the module and status of the resin and cure process by thermal imaging. The module is allowed movement by preset temperature monitoring by the thermal imaging software that controls the speed at which the module travels the liner of the pipe. All data including temperature, footage location of the module, pressure and video of the thermal image can be recorded on a DVD or some other recording device at the control station. A loss of fluid pressure during the process will lead to automatic shut down. 
     Once the resin reaches a critical cure point determined by the imaging software, a controlling unit communicates with the module and the winch. The winch then allows additional cable to be released which in turns allows the air pressure to further advance the module. The process repeats until the desired portion or all of the liner in the passageway or pipe has been sufficiently cured. The rate of speed of the module is dependent on external conditions and the type of resin used in the liner. The process may be a continuous process, or if necessary to properly cure the resin, the module may be held in place for a short time and then advanced. The thermal imaging camera and the software assist in the determination of the rate of speed of the movable module and completeness of the cure. 
     Once the module reaches the second end of the pipe, it is de-energized and can then be removed from the pipe. The cable and a power supply cable can be disconnected from the module and then the winch can retract the cable and/or the power supply cable, or the entire unit may be retracted to the starting point and removed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic front view of the system of the invention showing the curing module within a pipe between a first and second end; 
         FIG. 2  is a perspective view of the curing module of  FIG. 1 ; 
         FIG. 3  is a perspective view of the first end of the liner; 
         FIG. 4  is a perspective view of the second end of the liner; 
         FIG. 5  is a detailed view of a portion of the first end of  FIG. 3 ; 
         FIG. 6  is an end view of the curing module; 
         FIG. 7  is a sectional end view of a liner of the type used in carrying out the invention; and 
         FIG. 8  is view of the module partly in section to show the interior of another embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION 
     Now referring to the drawings,  FIG. 1  shows a system  10  for curing a liner  12  within a pipe  14 . The liner  12  has a first end  16  and a second end  18 . The liner  12  is placed in the length of the pipe  14  in any effective manner but preferably using the known method in which a liner is installed by everting the liner.  FIG. 7  shows the layers of a liner  12  of the type used in carrying out the invention. The layers typically include felt/fiberglass layers  15 , an impermeable coating layer  17  and may contain a microwave impermeable layer  19 . The impermeable coating layer  17  contains a resin material  82  that will partially or completely absorb incident microwave radiation in order to initiate or accelerate the cure process. The layer  19  will only be needed in certain cases and never extends the entire length of the liner. When used, the purpose of the layer  19  is to protect the operators at the exposed ends of the liner. Also, a screen may be placed over the manhole and over the exposed ends of the liner to prevent microwaves from escaping. The liner  12  is clamped at the first end  16  with a suitable clamping device (not shown). A covering  22  is placed and secured on the second end  18 , preferably through the use of clamps  24  and clamping ribs  26 . The second end  18  has an adjustable orifice  28  which allows the flow of air exiting the second end  18  to be controlled. The orifice  28  can be a ball valve. 
     A module  20  is placed in the liner  12  at the first end  16 . As shown in  FIG. 2  the module  20  has a front end  30  and a rear end  32 . The rear end  32  contains a mechanism for attaching a cable  34  to the module  20 . The cable  34  serves as the means to bring power from a suitable power supply  36  to the module  20  and connect the module  20  to a control station  38 . In order to prevent unwanted unplugging of the cable  34  from the module  20  toward the second end  18 , at least one secondary cable can be attached from the rear end  32  to a cable clamp  60 . The secondary cable  35  is of a length such that movement of the module  20  will exert pressure on the cable clamp  60 , therefore, preventing the cable  34  from unintentionally disconnecting from the module  20 . The cable  34  is also attached to a winch  44  which can be a part of the control station  38 . The module  20  includes a microwave applicator, such as magnetron  40 , positioned between the front end  30  and the rear end  32  and a thermal imaging device  42  positioned ahead of the magnetron  40 . Although the thermal imaging module  42  is shown as being mounted ahead of the magnetron  40 , it should be understood that the relative positions of the magnetron  40  and the thermal imaging module  42  could be reversed. 
     Again referring to  FIG. 1 , once the module  20  is introduced into the first end  16  of the liner  12 , a second covering  46  is placed over the first end  16  of the liner  12 . As shown in  FIGS. 3 and 5 , the second covering  46  is secured over the first end  16  of the liner  12 , preferably with clamps  24  and clamping ribs  26 . The second covering  46  includes a first opening  50  and a second opening  52 . The first opening  50  is connected to an air supply  54 , while the cable  34  is placed within the second opening  52 . A seal fits around the cable  34  and occupies the space between the cable  34  and the second opening  52  such that an air tight seal is formed. Preferably, the seal is a two-piece rubber seal  37  which includes an internal bevel  56  or flexible lips that seal while the liner  12  is pressurized. The seal  37  can be held in place with the use of an over-center clamp or other suitable means (not shown). 
     Again referring to  FIG. 2 , the module  20  is shown in greater detail. The module  20  is preferably of a shape similar to what is know in the art as a “pipe pig” which is typically used for cleaning pipes. The module  20  therefore has a main body  64  that is generally cylindrical in shape and hollow with a disc  62  at the front end  30  and a disc  72  at the rear end  32 . The discs extend outwardly beyond the main body  64  and the diameter of the discs  62  and  72  is such that the discs will come in contact with the inner diameter of the liner  12  and thus stabilize and guide the module as it is passed through the liner. Thus, the outer diameter of the discs  62  and  72  is preferably larger than the diameter of the main body  64 . The front portion of the disc  62  extends past the main body  64 . Preferably, the module  20  includes one of more middle discs  70  which has the same diameter as the discs  62  and  72 . As the diameters of pipes vary, modules of different diameters will be needed depending on the size of the particular pipe being lined. In practice, the module is used in pipes of at least four inches in diameter. 
     The portion of main body  64  between the discs  70  and  62  is a cylindrical exterior wall made of a material, such as glass, that forms a chamber between the discs  70  and  62 . The portions of the discs  70  and  62  inside the main body  64  are each preferably provided with a microwave screen which has a plurality of openings  68 , which screens confine the microwave energy emitted by the magnetron  40  to the chamber formed between the discs  70  and  62 . With the magnetron  40  mounted on the disc  70 , the microwaves will be directed into this chamber and allowed to pass through the exterior wall and be absorbed into the coating layer  17  of the liner  12 . The outer portions of each of the discs  70  and  62  that extend outwardly beyond the main body  64  preferably are of a metallic material or have a metallic backing to contain the microwaves emitted from the chamber and maximize absorption of the microwaves into the layer  17 . Similar to the components of the second embodiment shown in  FIG. 8  and described hereinafter, if desired, a mode stirrer may be provided on the disc  62  extending into the chamber to evenly distribute the microwave energy in the chamber. 
     Although it is to be understood that the module  20  can have different shapes and locations of certain components, the first embodiment of  FIG. 2  has the magnetron  40  located on the disc  70  and the thermal imaging device  42  mounted on disc  72 . The thermal imaging device  42  is preferably a digital camera capable of monitoring the temperature of the liner  12 . As illustrated by the embodiment of  FIG. 8 , It should be understood, however, that the module  20  may have as many as four discs forming three chambers, and that the microwave applicator and thermal imaging camera can be positioned in different relative locations as long as the components of the module are arranged to most efficiently contain and direct the microwave energy onto the liner  12  as the module is moved along the liner  12  in the manner described hereinafter. 
     Referring now to  FIG. 8 , the module  120  has a cylindrical shaped, hollow main body  64  that is divided into three chamber  190 ,  192  and  194  by discs  162  and  164  that include microwave screens  180  that confine microwave energy to the chamber  192 . The module  120  has a front end  30  and a rear end  32 . Front end  30  has a disc  62  that extends outwardly beyond the main body  64 . Similarly, rear end  32  has a disc  72  that extends outwardly from main body  64 . Mounted in chamber  190  is a magnetron  40  that has a microwave applicator  170  extending into chamber  192  to emit and dissipate microwaves throughout chamber  192 . If desired, an air-driven mode stirrer  196  can be used to assist in more evenly distributing the microwave energy. The portion of the main body  64  that forms the exterior wall  184  between discs  180 , is formed of a microwave transparent dielectric, such as glass, that allow the microwave energy in chamber  192  to pass through. The discs  162  and  164  are formed of a metallic material or provided with a metallic backing on the sides adjacent the exterior wall  184  to contain the microwaves and direct them to the portion of the liner  12  between the discs  162  and  164  where they can be absorbed by the resin in the liner  12 . A thermal imaging device, such as a camera  42  having a lens  190  extending into chamber  192 , is mounted in chamber  194 . Similar to the embodiment of  FIG. 2 , a cable  34  (not shown in  FIG. 8 ) can serve as the means to bring power from a suitable power supply  36  to the module  120  and connect the module  120  to a control station  38 . Cable  34  can contain a high-voltage DC cable  198  to power the magnetron  40  and cable  34  can also carry a line  200  to a detector  202  and a line  204  that is the power and video feed to the thermal imaging device  42 . As in the embodiment of  FIG. 2 , cable  34  is also connected to winch  44  to control movement of the module  120 . 
     In operation, and again referring to  FIG. 1 , after the module  20  or  120  (both referred to hereinafter as simply module  20 ) is inserted at the first end  16  of the liner  12  and the second covering  46  is secured over the first end  16 , the air supply  54  is connected to the second covering  46  at the first opening  50 . As air is pumped into the liner  12  through the second covering  46  toward the second end  18  of the liner  12 , the pressure created by the air begins to exert a force on the module  20 , while also keeping the liner  12  inflated and occupying the pipe  14 . If for some reason the air pressure falls below a certain pressure, pressure sensitive safety switches as well as horizontal level monitoring switches (not shown) can be combined with the module  20  to automatically shut down the module  20 . The force provided by the pressurized air is sufficient to propel the module  20  from the first end  16  to the second end  18  of the liner  12 . However, the cable  34  attached to the winch  44  maintains the module  20  in a particular location within the pipe  14 . By controlling the air pressure and the length of the cable  34 , the module  20  can be systematically and selectively moved by allowing a portion of the cable  34  to unwind from the winch  44 . The pressure from the air then moves the module  20  until the slack in the cable  34  is taken up. Once again the module  20  is stopped and maintained at a specific position until more cable is released by the winch  44 . The movement of the module  20  and the operation of the magnetron  40  is preferably controlled through the control station  38  located outside of the pipe  14 , and the movement of the module can be continuous or movement can be intermittent. To effectively cure most liner resins, movement of the module is typically about ten feet per minute. 
     As the module  20  makes its way through the pipe  14 , the magnetron  40  selectively emits radiation in the form of microwaves. The amount and intensity of the microwaves are preferably controlled by the power supply  36  and computer software housed at the control station  84  which also controls the winch  44 . The microwaves will effectively raise the temperature of the resin  82  in the layer  17  of liner  12  to accelerate the curing process. As previously described, the discs  70  and  72  of the module  20  and discs  162  and  164  of module  120  are made of materials that confine most of the microwaves into the chamber where the microwaves are applied so that the microwaves exit the module through the exterior wall of the chamber where they can be absorbed by the resin  82  of the liner  12 . The microwave impermeable layer  19  can help prevent microwaves escaping to the outside environment. The thermal imaging device  42  monitors the status of the temperature of the resin  82  in the liner  12 . Once the resin and catalyst combination reach a temperature that causes an exothermic reaction, movement of the module  20  can advance and will be moved a selected distance within the pipe  14  to begin to cure another portion of the resin  82  in the liner  12 . The process is repeated or run continuously until the entire length of the liner has been treated. 
     Once the module  20  has reached the second end  18  of the liner  12 , the covering  22  can be removed from the second end  18  and the module  20  removed and the cable  34  disconnected from the module  20 . The winch  44  can then be reversed to extract the cable  34  from the first end  16 . The second covering  46  can then be removed as well, leaving a cured liner  12  in the pipe  14 . 
     Having thus described the invention in connection with the several embodiments thereof, it will be evident to those skilled in the art that various revisions can be made to the several embodiments described herein with out departing from the spirit and scope of the invention. It is my intention, however, that all such revisions and modifications that are evident to those skilled in the art will be included with in the scope of the following claims. Any elements of any embodiments disclosed herein can be used in combination with any elements of other embodiments disclosed herein in any manner to create different embodiments.