Abstract:
Joints or other discontinuities in a live gas pipeline are sealed by attaching an insertion duct to the exterior of the pipeline, inserting a spraying device into the pipeline through the insertion duct, mechanically orienting the spraying device adjacent the joint or other discontinuity and spraying a coating material onto the interior surface of the pipeline wherein the coating material may be applied and will cure in the presence of pressurized flowing gas.

Description:
This is a division of 09/047,837 filing date Mar. 25, 1998 now U.S. Pat. No. 5,913,977. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to an apparatus and method for internally coating live gas pipeline or conduit. Particularly, this invention relates to internally coating pipe joints or other discontinuities in live propane or natural gas pipeline. Even more particularly, this invention relates to internally coating pipe joints or other discontinuities in live propane or natural gas pipeline using a self-aligning, explosion-proof coating device capable of coating several hundred feet of live underground gas pipeline while requiring only a single excavation. 
     2. Description of the Related Art 
     A dilemma has arisen in the gas and gas transportation industry. Low-moisture gas, such as propane or natural gas, has replaced high-moisture manufactured gas, such as coal gas, as a source of domestic and industrial fuel. Traditionally and for many decades coal or other high-moisture gases were fed to customers by underground pipes. Typically these gas pipelines were constructed of individual lengths of pig or cast iron pipe. These individual lengths of pipe were commonly joined together by bell or lap joints that were sealed with a combination of a filler material and lead. Several different types of filler material were used including horsehair, yarn, jute and hemp. It was discovered that, as many municipalities converted from high-moisture manufactured gas to the relatively low-moisture propane or natural gas, the filler material in the pipe joints would dry out. As these filler materials dried out they would decompose and disintegrate, thereby causing gas leaks to appear at the pipe joints. 
     The decay of joint filler due to the conversion to low-moisture gas is not unique to the United States. The United Kingdom is experiencing similar decay of their gas pipe joint filler. As a preventative measure, and as an attempt to slow down the decay of filler material, many gas companies in the United Kingdom, and a few in the United States, routinely “fog” their gas lines. Fogging normally involves sending a glycol type product through the gas pipeline to enhance the moisture content of the filler. Another method of maintaining high moisture in the filler involves a process known in the gas industry as humidification. This process requires repeated application of pressurized steam to a gas pipe system. 
     Unfortunately, these preventative procedures are only temporary and can be quite costly. Today, to adequately prevent gas from escaping these types of pipelines, the pipe joints or other discontinuities must be sealed or replaced. Because many of these pipelines are underground and not readily accessible, excavating, removing and replacing an entire length of pipeline having deteriorated pipe joints is drastic and quite costly. 
     One method of sealing these pipe joints or discontinuities against gas leaks includes excavating an end of the pipe and having someone climb into the pipe to hand apply a coating compound. This method can be quite expensive and time consuming. Also, this method can be dangerous and is unfeasible for small diameter pipe. Another technique includes inserting a permanent lining throughout the entire length of pipe. Again this is quite costly and may cause an unacceptable reduction in the flow capacity of the pipe. Also, this method requires a large consumption of natural resources to fabricate a lining for an entire length of pipe, when typically only the joints are susceptible to leaking. 
     Still another method, such as U.S. Pat. No. 4,178,875 (1979, Moschetti) includes sending a device through the pipe that can remotely detect a joint or other discontinuity that needs repair. A coating material is then sent through attached tubing and is sprayed onto the inner surface of the pipe at the desired location. However, this and the above-mentioned methods are not performed on “live gas pipe” (pipe in which pressurized gas remains flowing). These methods require the gas flow to be shut down for long periods of time. Depending on the customers being serviced by the gas line, it is normally unacceptable to interrupt service for such long periods of time. Another disadvantage of these methods is that they require more than a single excavation when coating long lengths of pipeline. 
     Still other methods are known whereby the gas remains live while coating, repairing or sealing is accomplished. U.S. Pat. Nos. 4,582,551 and 4,627,471 (1986, Parkes et al.) disclose a method and device that can remotely seal joints or leaks in a pipe while the gas continues flowing in the pipe. The device is inserted into a pipe whose inner diameter is slightly larger than the outer circumference of the device. The device uses expandable bladders to form a substantially air-free environment, thereby isolating the joint or discontinuity from pressurized gas. The pressurized gas is rerouted through the interior of the device. Anaerobic sealant is then pumped to the device and the sealant is sprayed onto the interior of the pipe at the desired location. The device remains in place long enough to allow the anaerobic sealant to setup. A disadvantage with this device is that it requires an environment free from air and flowing pressurized gas in which to apply sealant. Another disadvantage with these types of devices is that they are limited in their ability to maneuver around corners or other obstacles in the pipeline as they are in close proximity to the interior of the pipe. Still another disadvantage with these devices is that they are slow and time consuming because they require the device to remain in place while the sealant sets. 
     Another method of sealing pipe joints in a live gas pipe is taught in U.S. Pat. No. 5,156,886 (1992, Kitson). This method involves inserting a nozzle attached to a hose through a tapping mandrel to a desired location in a live gas pipe, whereby an anaerobic sealant is pumped through the hose to the nozzle. The nozzle sprays the anaerobic sealant onto the interior of the pipe. This method works well on relatively short lengths of pipe. However, as the length of tubing increases, the viscosity of the anaerobic sealant prevents it from reaching the spraying device in adequate quantities. Also, as the length of tubing increases, static electric charges build up in the line due to the friction caused by the sealant rubbing against the interior of the tubing. This can pose serious problems when working in a live gas setting. Another drawback with this device is that the anaerobic sealant tends to pool in the bottom of the pipe upon application. An additional drawback of this method is that it typically requires the presence of some filler to properly seal a leaking joint. Because the above-mentioned preventative or fogging measures were never routinely performed in the United States, much of the filler in United States gas pipe joints has disintegrated, making this method of sealing pipe joints impractical. 
     What is needed is an apparatus and method for coating or sealing the interior of very long lengths of underground pipe or other conduit, either at a joint, another type of discontinuity or along the entire length of the pipe, while the gas in the pipe remains live. What is also needed is an apparatus and method of internally coating live gas pipe joints that do not require the presence of filler material in a joint to efficiently seal it. What is further needed is an apparatus and method that allow for several layers of coating material to be applied at the same site, that provide a rapid coating process, that do not require the coating device to remain in place while the coating material sets, that can be inserted into a live gas pipe using a variety of means, that can maneuver around bends and other obstacles normally found in gas pipe, and that can be safely operable in live gas settings. Finally, what is needed is an apparatus and method that applies an epoxy-type sealant that will coat the interior of a variety of different pipe surfaces, with or without the presence of pressurized gas, with or without the presence of air or oxygen and that will not produce significant pooling of the coating material in the bottom of the pipe upon application. 
     SUMMARY OF THE INVENTION 
     It is therefor an object of the present invention to provide an apparatus and method for coating or sealing the interior of very long lengths of underground pipe or other conduit, either at a joint, another type of discontinuity or along the entire length of the pipe, while the gas in the pipe remains live. 
     It is another object of the present invention to provide a method and apparatus that does not require the presence of filler material to efficiently seal a joint or other discontinuity. 
     It is still another object of the present invention to allow for several layers of coating material to be applied at the same site. 
     It is a further object of the present invention to provide a rapid coating process, which does not require the coating device to remain in place while the coating material sets. 
     It is a further object of the present invention that it can be inserted into a live gas pipe using a variety of methods. 
     It is a further object of the present invention that it can maneuver around bends and other obstacles normally found in gas pipe. 
     It is still a further object of the present invention that it be safely operable in live gas settings. 
     It is still a further object of the present invention that it applies an epoxy-type sealant that will coat the interior of a variety of different pipe surfaces, with or without the presence of pressurized gas, with or without the presence of air or oxygen and that will not pool in the bottom of the pipe upon application. 
     It is still a further object of the present invention that it requires only a single excavation to repair several hundred feet of live underground pipe. 
     These objects are achieved by providing an apparatus and a method for coating or sealing the interior of underground pipes where the apparatus is moved through the pipe while the gas is flowing. The coating device is connected to reservoirs of coating material and is specially designed to operate in the presence of propane or natural gas without incident. In addition, an epoxy-type coating material is utilized that will adhere to a variety of surfaces and that will set-up within a variety of climates, including a pressurized live gas environment. 
     To prevent electric discharge caused by friction, resulting from the individual components of coating material traveling to the coating device, the coating material components are pumped to the coating device through a series of non-conductive or electrically grounded tubing. This makes the device safer to operate in a live gas environments. 
     The present invention also includes scissor-type expansion legs. These scissor-type legs allow the present invention to maneuver around corners and bends in the pipe, and to adapt to a wide variety of pipe diameters. Also, the combination of a non-conductive or electrically grounded delivery system with a specially designed pushing system, allow greater lengths of pipe to be sealed or repaired with fewer excavations than known related art devices and techniques. 
     As thousands of miles of these types of pipe deteriorate all over the United States and the rest of the World, and because the present invention allows several hundred feet of underground pipe to be coated or repaired using a single excavation, the required number of excavations needed to repair the deteriorating pipe and pipe joints will be greatly reduced. Therefore, the energy and natural resources required to restore the excavated repair sites will also be greatly reduced. In addition, the present invention will provide an economically feasible method of repair that allows indefinite postponement of the replacement of thousands of miles of gas pipeline, thereby preserving the enormous quantities of natural resources that would be required to fabricate replacement pipe. As many of these pipe joints and other discontinuities are sealed, the loss of natural or propane gas will be greatly reduced, as will the consumption of enormous amounts of glycol and other joint filler preserving compounds. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a detailed side view of the coating device and the semi-flexible containment tube of the present invention showing the device situated inside a section of gas pipe. 
     FIG. 2 is a cross-sectional view of the containment tube of the present invention showing the different dedicated hoses, rods and tubes required for operation of the coating device shown in FIG.  1 . 
     FIG. 3 is a schematic view of an excavation site showing an exposed length of gas pipe and a bypass system that allows the gas to remain flowing in the pipe. 
     FIG. 4 is a schematic view of an excavation site showing a section of gas pipe removed and an end cap placed on an exposed end and a gas bypass system that allows the gas to remain flowing in the pipe. 
     FIG. 5 is a side view of a containment tube pushing unit of the present invention. 
     FIG. 6 is an enlarged side view of a flywheel from the containment tube pushing unit shown in FIG.  5 . 
     FIG. 7 is a side view of an entry unit of the present invention. 
     FIG. 8 shows the entry unit as shown in FIG. 7 attached to a gas pipe with a coating apparatus of the present invention resting within the gas pipe. 
     FIG. 9 is a schematic view of an excavation site showing the entry unit shown in FIG. 7 attached to an exposed end of gas pipe. 
     FIG. 10 is a schematic view of an excavation site showing the containment tube pushing unit shown in FIG. 5 attached to the entry unit as shown in FIG.  7 . 
     FIG. 11 is a schematic view of an excavation site showing a split sleeve dresser entry unit of the present invention attached to a gas pipe. 
     FIG. 12 is a schematic view of an excavation site showing the containment tube pushing unit shown in FIG. 5 attached to the split sleeve dresser shown if FIG.  11 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The preferred embodiment of the present invention is illustrated in FIGS. 1-11. Referring now to FIG. 1, a coating device, generally designated by numeral  10 , is shown located resting on an inside surface  12  of a pipe  14 . The coating device  10  is provided with a centering carriage  20 . The centering carriage  20  has a front end  16  and a rear end  18 . A manifold  82  is attached to the rear end  18 . A containment tube  60  is shown attached to manifold  82 . An air motor  38  is mounted inside the front end  16  of centering carriage  20 . Air motor  38  turns a rotating slotted head  40 . A static mixer  50  is fixed to the side of centering carriage  20 . Individual coating material components are sent to the static mixer  50  through intake tubes  86  and  88  where they are thoroughly mixed to produce a coating material  48 . The coating material  48  is then sent through an outlet tube  32  where it is forced into a spray tip  36 . Spray tip  36  then meters an appropriate amount of coating material  48  into rotating slotted head  40 , which centrifugally disperses coating material  48  onto the inside surface  12  of pipe  14 . 
     The centering carriage  20  is provided with a plurality of adjustable-length scissor-type expansion legs  22  for support. Each scissor-type expansion leg  22  is attached to a compressed gas powered piston  58 , which is mounted inside the rear end  18  of centering carriage  20 . Wheel assemblies  28   a  and  28   b  are attached to the ends of the adjustable-length scissor-type expansion legs  22 . The wheel assemblies  28   a  and  28   b  are shown in contact with the inside surface  12  and allow for lateral movement of coating device  10  through pipe  14 . The scissor-type expansion legs  22  are shown having four hinged members  24 ,  26 ,  28 , and  30 . The number of hinged members may be increased or decreased to accommodate different diameters of pipe  14 . 
     An illuminating explosion-proof monitoring camera probe  44  is attached to centering carriage  20 , by way of a monitoring probe mount  34 . An explosion-proof camera probe cable  70  is attached at one end to the illuminating explosion-proof monitoring camera probe  44  and at the other end to a control console. The illuminating explosion-proof monitoring camera probe  44 , which is powered by the explosion-proof camera probe cable  70 , is positioned to allow an operator to locate sections of pipe  14  that require treatment by the coating device  10 . The explosion-proof monitoring camera probe  44  lights the inside surface  12  of pipe  14 , and relays images of the inside surface  12  back to the control console. 
     As the coating device  10  is progressed laterally through pipe  14  an operator is able to monitor joints or other discontinuities by viewing a monitor on the control console. The operator can remotely control the application of coating material  48  to the inside surface  12  of pipe  14 . Upon discovery of a joint or discontinuity, a specific amount of coating material  48  is metered onto inside surface  12 . 
     The preferred coating material  48  is two-part epoxy-type elastomeric polyurethane sold under the name PLASITE PERMA-THANE 2300. Coating material  48  is capable of filling and coating large joints or other discontinuities. Coating material  48  can be used in a variety of environments including pressurized gas, air or oxygen. Depending upon the desired thickness of coating material  48  required, an operator can reposition coating device  10  and repeat the coating process described above. 
     Referring now to FIG. 2, a cross-sectional view of containment tube  60  is shown. Containment tube  60  houses non-conductive sealant component hoses  62  and  64 , compressed gas hoses  66 ,  68  and  78 , sealed explosion-proof camera probe cable  70 , exhaust hoses  72  and  74 , and an optional flexible stabilizing rod  80 . Containment tube  60  serves to protect the various hoses, tubes and rods it surrounds from abrasion. Also, containment tube  60  is flexible enough to maneuver around tight corners and bends in pipe, and is rigid enough to provide for the lateral movement of the coating device  10  in long lengths of pipe. Additionally, containment tube  60  serves to exhaust the gas used to power the air motor  38  and operate the scissor-type expansion legs  22  outside pipe  14 . 
     The non-conductive sealant component hoses  62  and  64  provide the individual coating material components to the intake tubes  86  and  88 , respectively. The compressed gas hose  66  provides compressed gas for manipulating piston  58  which controls the expansion and contraction of the scissor-type expansion legs  22 . Compressed gas hose  68  is used for powering air motor  38 , which in turn powers slotted spray head  40 . The sealed explosion-proof probe cable  70  is used for powering, lighting and receiving information from explosion-proof monitoring probe  44 . Exhaust hose  72  exhausts the compressed and other gases outside pipe  14 . Compressed gas hose  78  supplies compressed gas for purging any unused sealant  48  from the coating device  10 . The optional flexible stabilizing rod  80  provides for additional rigidity within containment tube  60  and allows for additional lateral force to be applied to the coating device  10 . 
     Referring now to FIG. 3, a schematic view of an excavated section of live gas pipe  14 , having a first section  202  and a second section  204  is shown. Tap holes  212  and  214  are drilled in sections  202  and  204  respectively. Next a temporary by-pass  210  is connected between drilled holes  212  and  214  to allow the gas to remain flowing in pipe  14  while a section is removed to allow for the insertion of coating device  10 . The temporary by-pass  210  is equipped with a pressure gauge  216  and a shut-off valve  218 . 
     Holes  222  and  224  are drilled, tapped and plugged in section  202  and holes  226  and  228  are drilled, tapped and plugged in section  204  of the excavated section of live gas pipe  14 , between the drilled holes  212  and  214 . The plugs are then removed from the drilled holes  222 ,  224 ,  226  and  228 , and inflatable bladders  232 ,  234 ,  236  and  238  are inserted through the drill holes  222 ,  224 ,  226  and  228  respectively. 
     Inflatable bladders  232  through  238  are inflated to create a gas impermeable seal within pipe  14 . Depending upon the pressure and the direction of the gas flowing in pipe  14 , fewer or additional inflatable bladders may be employed to control the flow of gas in pipe  14 . Opening the shut-off valve  218  diverts the flow of gas in pipe  14  through the temporary by-pass  210 . With inflatable bladders  232 ,  224 ,  226  and  238  still inflated, a length of pipe located between inflatable bladders  234  and  236  is removed. 
     Referring now to FIG,  4 , the now exposed end  206  of section  202  is shown sealed off with cap  248 . Inflatable bladders  232  and  234  may then be removed without allowing gas to escape from pipe  14 . The gas in pipe  14  continues to flow through temporary by-pass  210 . 
     Referring now to FIG. 5 a pushing unit  150  is shown. FIG. 5 shows pushing unit  150  having a first end  156 , a second end  158 , and an outside surface  160 . Pushing unit  150  controls the movement of containment tube  60  in pipe  14 , which in turn controls the lateral movement of coating device  10 . A power mechanism  154  is attached to outside surface  160 . A control mechanism  152  is operatively connected to power mechanism  154  and controls the rate at which power mechanism  154  operates. Containment tube  60  is shown entering pushing unit  150  through first end  156  and exiting pushing unit  150  through second end  158 . A plurality of flywheels  162  are powered by power mechanism  154  and operate to maneuver containment tube  60  through pushing unit  150  and into and out of pipe  14 . 
     FIG. 6 shows an enlarged side view of a single flywheel  162 , having a curved inner surface for receiving containment tube  60 . 
     Referring now to FIG. 7 a side view of a preferred insertion duct  240  is shown. Insertion duct  240  has a first end  242  and a second end  244 . Insertion duct  240  is fitted with a gate-valve  246  in second end  244 . Gate valve  246  closes to form a gas impermeable seal about containment tube  60 , which permits containment tube  60  to pass through it while preventing gas from escaping from pipe  14 . Insertion duct  240  is shown having a preferred curve shape. This design facilitates the insertion of containment tube  60  and coating device  10  into pipe  14  and allows for a smaller section of pipe  14  to be removed. A straight or other shaped insertion duct may also be used. 
     Referring now to FIG. 8 insertion duct  240  is shown attached to a section of gas pipe  14 . Coating apparatus  10 , as shown in FIG. 1, is shown situated in pipe  14 . 
     Referring now to FIG. 9, second end  244 , of insertion duct  240 , is shown bolted or otherwise fastened to the now exposed end  208  of pipe  14 . 
     Referring now to FIG. 10, second end  158 , of pushing unit  150 , is shown attached to first end  242  of insertion duct  240 . Prior to bolting or otherwise fastening pushing unit  150  to insertion duct  240 , containment tube  60  is inserted through pushing unit  150  and attached to coating device  10 . Coating device  10 , attached to containment tube  60 , is then inserted into first end  242  of insertion duct  240 , through gate-valve  246  and into pipe  14 . Second end  158  of pushing unit  150  is then secured to first end  242  of insertion duct  240 . After pushing unit  150  is secured to insertion duct  240  inflatable bladders  236  and  238  are deflated and removed and drill holes  226  and  228  are plugged. 
     An operator can then laterally relocate coating device  10  hundreds of feet down pipe  14  away from section  204  to a desired location with control unit  152 . Control unit  152  adjusts the rate of speed of power mechanism  154 , which in turn controls the speed of flywheels  162 . Flywheels  162  feed containment tube  60  into pipe  14 , which laterally moves coating device  10 . The operator can then monitor the inside surface  12  of pipe  14  using the images sent back along explosion-proof camera probe cable  70  from the explosion-proof monitoring camera probe  44 . 
     Once a joint or other discontinuity has been located the operator may then remotely apply coating material  48 . The operator controls the thickness of coating material applied to inside surface  12  by controlling both the rate of lateral movement of coating device  10  and by controlling the flow rate of the individual sealant components. When the operator has finished coating and sealing a section of pipe  14  with coating material  48 , the static mixer  50 , the spray tip  36 , the outlet tube  32  and the rotating slotted head  40  may be purged of coating material  48  by forced compressed gas provided by compressed gas purging line  78 . 
     Once the desired length of pipe  14  leading away from section  204  is sealed, pushing unit  150 , insertion duct  240  and coating device  10  are removed in reverse order as above-described and an end cap  248  is placed over exposed end  208 . 
     To seal the length of pipe  14 , leading away from exposed end  202 , drill holes  236  and  238  are unplugged and inflatable bladders  236  and  238  are reinserted and inflated. End cap  248  is removed from section  202  of pipe  14  and insertion duct  240  is mounted to exposed end  206  in its place. Coating apparatus  10  is then inserted into section  202  and pushing unit  150  is attached to insertion duct  240 . The inspection and treating procedure is the same as described above. 
     Referring now to FIGS. 11 and 12, a second method is revealed for inserting coating device  10  into live gas pipe  14 . FIG. 11 depicts an excavated section of live gas pipe  14 . A two-piece split-sleeve dresser  110 , having a first end  102  and a second end  104 , is put in place and bolted around the outer circumference  24  of a section of live gas pipe  14 . Angled sections  106  and  108 , containing gate valves  126  and  128  respectively, are then attached to an outer surface  120  of the split-sleeve dresser  110 . 
     FIG. 12 shows pushing unit  150  attached to angled section  106 . Pushing unit  150  controls the lateral movement of coating device  10  in the same manner as described above. Once the desired length of pipe  14  has been treated and inspected using coating device  10  it may be removed from pipe  14 . 
     Prior to the attachment of pushing unit  150 , a drilling unit is mounted to a faceplate  132  of angled section  106 . Gate valve  126 , located within angled unit  106 , is opened as the drilling unit drills a hole  142  (not shown) through the two-piece split-sleeve dresser  110  and into pipe  14 , at the point where angled section  106  and split sleeve dresser  110  intersect. Hole  142  is large enough to allow coating device  10 , attached to containment tube  60 , to be inserted into pipe  14 . Gate valve  126  is then closed and the drilling unit is removed. 
     Containment tube  60  is threaded through pushing unit  150  and attached to coating device  10 . Coating device  10  is then inserted into angled section  106 . Second end  158  of pushing unit  150  is then bolted or otherwise fastened to face plate  132  of angled section  106 . An inflatable packing gland  138  is then inserted into pushing unit  150  and is positioned around containment tube  60 , to form a gas impermeable seal. Inflatable packing gland  138  prevents gas from escaping pipe  14  while allowing containment tube  60  to pass through hole  142  into pipe  14 . Once inflatable packing gland  138  is in place, gate valve  126  is opened and coating device  10  is pushed through hole  142  and into pipe  14 . 
     A length of gas pipe section leading away from split sleeve dresser end  104 , may be inspected and treated in the same manner as described above. First, an operator relocates the coating device  10  the desired distance down pipe  14 . The operator then maneuvers the coating device  10  back to the split sleeve dresser  110  inspecting and coating joints or other discontinuities along the way. After the section of pipe leading away from split sleeve dresser end  104  has been treated, the coating device  10  is returned to angled section  106 . Gate valve  126  is closed and the pushing unit  150  is removed. A cap  136  (not shown) is then bolted or otherwise fastened to face plate  132 . 
     In order to inspect and treat the section of gas pipe extending away from split sleeve dresser end  102 , a hole  144  (not shown) similar to hole  142 , is cut into pipe  14 , within angled section  108  and through the two-piece split-sleeve dresser  110 . Hole  144  is large enough to allow coating device  10 , attached to containment tube  60 , to be inserted into pipe  14 . Coating device  10  is then inserted through angled section  108  through hole  44  and into pipe  14 . After the section of gas pipe extending away from split sleeve dresser end  102  has been inspected and treated, and coating device  10  has been removed, a cap  146  (not shown) is secured to face plated  134 . After both sections of pipe  14 , leading away from the split sleeve dresser  110  have been inspected and treated, and angled sections  106  and  108  have been capped, the split sleeve dresser  110  is left in place and the excavation is filled in. 
     Depending upon the amount of build up of debris on inside surface  12  of pipe  14 , a cleaning device may be attached to containment tube  60  and fed through pipe  14  using the same methods as described above. Preferred cleaning devices are self-centering, powered by compressed air, explosion proof and propel an abrasive at the inside surface  12 . The abrasive effectively and efficiently reconditions the inside surface  12 . After reconditioning, the cleaning device is removed to allow for the insertion of coating device  10 .