Patent Publication Number: US-11654445-B2

Title: Automatically adjustable tool for holding a spray painting instrument for painting an infernal surface of a pipe

Description:
CLAIM FOR PRIORITY 
     This is a divisional application of Non-Provisional U.S. patent application Ser. No. 16/597,031 filed Oct. 9, 2019, which was based on U.S. Provisional Patent Application Ser. No. 62/743,192, filed on Oct. 9, 2018. The priorities of the foregoing applications are hereby claimed and their disclosures incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates generally to internal coating of pipes and tubes, and more particularly, to a tool used for holding a spray gun for coating internal surfaces of pipes and tubes. 
     BACKGROUND OF THE INVENTION 
     Internal coating or painting of pipes and tubes is essential in many industries, including oil &amp; gas and marine industries. Various pipes are applied with internal coatings to protect them from the effects of corrosion and erosion caused by the fluids carried by the pipes. The internal coatings also reduce friction and turbulence between an internal surface of the pipe and the fluid flowing therein. This in turn increases the flow efficiency of the fluid. The coatings can be of epoxy, such as liquid epoxy and internal fusion bonded epoxy (FBE), paints, amine cured glass and ceramic coatings, such as the NOVA-Plate® 325 by the Sherwin Williams Company, and the like. 
     The internal surface of the pipes may suffer premature corrosion due to coating failures. A major cause of premature corrosion is the flaws in the finished coating, often referred to as porosity of the coating. A “holiday detection test” is used to detect the porosity (holes or discontinuity in the coating) that allows detection of flaws invisible to the naked eye. Holiday detection techniques such as JEEP, porosity detection, pinhole testers, and spark testers are well known in the art. 
     For internal coating of pipes having large diameters (for example, diameters greater than 12 inches), various tools are commercially available. These tools typically include a rotary paint spray gun that centrifugally dispenses the coating fluid on to the internal surface of the pipe. The rotary paint spray gun is often held in place by using a support and is maneuvered inside the pipe along its length either manually or by using an automated mechanism. For example, U.S. Pat. No. 4,036,173 issued to Nicklas, is directed towards a method and apparatus for sandblasting and coating interior surfaces of pipes. U.S. Pat. No. 4,335,677 issued to Nagata et al. is directed to a tool for coating the inner surfaces of tubes, and U.S. Pat. No. 4,891,115 issued to Shishkin et al. is directed to a cleaning tool for use on inner surfaces of pipelines. These tools are not shown to paint up to 90 degree angles within a pipe. 
     Manual maneuvering of the rotary paint spray guns is cumbersome, especially in cases when the pipes have long lengths. In addition, the quality of coatings thus applied suffers due to uneven and intermittent spraying of the coating material. One known solution to overcome this problem includes use of a tool to firmly hold and maneuver the rotary paint spray gun. For example, commercially available ‘HDCBX-360-3 Paint Spray Coater™ by the Clemtex Company includes a centering carriage having a scissor like arrangement of arms. The arms are adjustable in their height by using a threaded screw arrangement. The centering carriage holds a centering sheave therein, which is used to hold a spinning head of a rotary paint spray gun at one end thereof. The hose of the rotary paint spray gun passes through the centering sheave. The hose is connected to a paint pump or pressure tank. The paint pump forces the coating fluid through the spray gun and the hose to the spinning head. The paint is slung by centrifugal force produced by the spinning head in a 360-degree pattern. The volume of paint directed to the spinning head can be adjusted by the pressure on the paint pump or by a pre-orifice used in a back-pressure orifice assembly. The wet film thickness of the paint is controlled by the speed with which the Spray Coater™ is moved through the pipe. 
     Another known solution is the Orbiter™ tool marketed by Clemco Industries. The Orbiter™ tool includes a control gun assembly that includes an adjustment lever and a pressure regulator for a centering carriage. A paint spray gun mounts on the control gun assembly. Centering carriages expand and collapse by use of an air cylinder. Manual adjustment of leg expansion is facilitated during operation to compensate for bends or protrusions in pipe. Scissor-type expansion legs are operated by an air cylinder and are regulated by the control gun assembly. Extension and retraction of the expansion legs is made possible due to the scissor type mechanism. A pressure regulator allows adjustment to the amount of air passing through the air cylinders. The pressure may be reduced to collapse the carriage appropriately when going around pipe angles. When the pressure is returned to its higher reading, the carriage expands to its full extension. 
     In addition, the “DP-IP01 Internal Pipe Painting Equipment™” by the DP Airless Company provides a threaded bolt-based height adjustment mechanism for three scissor arms. While the tool can be used for painting the interior of pipes having small diameters, it suffers from certain drawbacks as discussed below. 
     One of the major drawbacks associated with the tools descried herein is the need to adjust the distance between arms according to varying diameters of pipes. This adjustment requires manual efforts and undue experimentation by the technician operating the tools. Presently, the commercially available tools do not offer a suitable solution to overcome this drawback. In addition, since the distance between the arms (i.e., the height of the tool) is not automatically adjustable, it is difficult for the tool to maneuver around bends or angular parts of the pipes. For example, it becomes difficult for such tools to turn around an obtuse angle of a pipe. It becomes more difficult in cases of right angled bends in pipes. Moreover, the typical spray painting applications entail high operating pressures and the current tools fail in withstanding such high pressures without significant mechanical robustness, thereby increasing their costs of manufacturing. Finally, the bulky construction of the tools pose challenges when such tools are used in applications involving pipes of small diameters, for example, diameters less than about four (4″) inches or six inches (6″). However, it should be noted that difficulties exist with current tools used to coat pipe interiors less than about ten inches (10″). 
     In light of the foregoing, there exists a need for a reliable solution that overcomes one or more abovementioned problems of the existing solutions. The tool should eliminate the need for manual intervention in adjusting its height for varying tube diameters. In addition, the tool should work effectively with pipes having diameters between two (2) and ten (10) inches, and generally smaller than about 6-10″. Finally, the tool should be simple in construction yet withstand high pressure painting operations. 
     SUMMARY OF THE INVENTION 
     Disclosed herein is a simple tool to hold a paint spray gun, capable of handling high pressure while in operation. The tool has retracting arms which roll within the confines of the (interior of the) pipe and can maneuver within curves and angles up to 90°. Embodiments of the invention provide a tool for holding a spray painting gun for coating an internal surface of a pipe and in particular, coating the interior of curves and 90° angles of pipes. A central hub includes a hollow tube for carrying the spray painting gun. At least two projections extend outwardly from an outer surface of the hollow tube. First and second retracting arms are provided for each projection. Each retracting arm includes a roller attached a first end thereof. Further, first and second pivot pins pivotably attach the first and second retracting arms, respectively, to each projection. A retraction mechanism is provided for each retracting arm and includes first and second fixed pins provided on each projection and first and second springs that connect second ends of the first and second retracting arms to the first and second fixed pins, respectively. The retraction mechanisms facilitate a pivotal movement of the first and second retracting arms about the first and second pivot pins, respectively. In operation, the tool is inserted inside the pipe such that each roller touches the internal surface of the pipe due to an outward force exerted by each retracting arm. The tool is movable inside the pipe and carries the spray painting gun inside the pipe for facilitating coating of the internal surface thereof. Moreover, the tool adjusts automatically to different pipe diameters due to its retracting arms. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings illustrate the various embodiments of systems, methods, and other aspects of the invention. It will be apparent to a person skilled in the art that the illustrated element boundaries (e.g., boxes, groups of boxes, or other shapes) in the figures represent one example of the boundaries. In some examples, one element may be designed as multiple elements, or multiple elements may be designed as one element. In some examples, an element shown as an internal component of one element may be implemented as an external component in another, and vice versa. 
       Various embodiments of the present invention are illustrated by way of example, and not limited by the appended figures, in which like references indicate similar elements, and in which: 
         FIG.  1    is a perspective view of a tool used for coating an internal surface of a tubular pipe; 
         FIG.  2    is a front view illustrating the tool of  FIG.  1    when inserted inside a straight section of the tubular pipe; 
         FIG.  3    is a side view corresponding to the front view of  FIG.  2   ; 
         FIG.  4    is a perspective view of the tool of  FIG.  1   , when inserted inside a curved section of the tubular pipe; and 
         FIG.  5    is a schematic diagram showing the tool of  FIG.  1    in operation, along with a system used for coating an internal surface of the tubular pipe. 
     
    
    
     Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description of exemplary embodiments is intended for illustration purposes only and is, therefore, not intended to necessarily limit the scope of the present invention. 
     DETAILED DESCRIPTION OF EMBODIMENTS 
     As used in the specification and claims, the singular forms “a”, “an” and “the” include plural references unless the context clearly dictates otherwise. For example, the term “an article” may include a plurality of articles unless the context clearly dictates otherwise. 
     Those with ordinary skill in the art will appreciate that the elements in the Figures are illustrated for simplicity and clarity and are not necessarily drawn to scale. For example, the dimensions of some of the elements in the Figures may be exaggerated, relative to other elements, in order to improve the understanding of the present invention. 
     There may be additional components described in the foregoing application that are not depicted on one of the described drawings. In the event, such a component is described, but not depicted in a drawing, the absence of such a drawing should not be considered as an omission of such design from the specification. 
     Before describing the present invention in detail, it should be observed that the present invention utilizes a combination of system components which constitutes a tool used for painting an internal surface of a tubular pipe. Accordingly, the components and the method steps have been represented, showing only specific details that are pertinent for an understanding of the present invention so as not to obscure the disclosure with details that will be readily apparent to those with ordinary skill in the art having the benefit of the description herein. 
     As required, detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention, which can be embodied in various forms. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present invention in virtually any appropriately detailed structure. Further, the terms and phrases used herein are not intended to be limiting but rather to provide an understandable description of the invention. 
       FIG.  1    illustrates a perspective view of a tool  100  used for coating an internal surface of a tubular pipe. The tool  100  includes a central hub  102 . The central hub  102  includes a hollow tube  104  and first through fourth projections  106   ab ,  106   cd ,  106   ef , and  106   gh  (collectively referred to as ‘projections  106 ’) that are formed on an outer surface of the hollow tube  104  and are preferably equally spaced apart with respect to an outer circumference of the hollow tube  104 . In the exemplary scenario with four projections  106  illustrated here, the four projections  106  are preferably spaced apart from each other by 90-degrees. A first retracting arm  108   a  and a second retracting arm  108   b  are removably and pivotally attached to the first projection  106   ab  by means of a first pivot pin  112   a  and a second pivot pin  112   b , respectively. The first and second retracting arms  108   a  and  108   b  are pivotable with respect to the pivot pins  112   a  and  112   b  respectively. A first roller  110   a  is attached at a first end of the first retracting arm  108   a . Similarly, a second roller  110   b  is attached to a first end of the second retracting arm  108   b . The rollers  110   a  and  110   b  may be ball bearings that are attached to the first and second retracting arms  108   a  and  108   b  by using respective pins and are freely movable with respect to the respective pins. Such attachments are well known in the art and their further description is avoided for the sake of brevity. 
     A second end of the first retracting arm  108   a  is attached to a first fixed pin  114   a  by using a first spring  116   a , such as a helical compression spring. The first spring  116   a  pulls the second end of the first retracting arm  108   a  towards the first fixed pin  114   a . Since the first retracting arm  108   a  is pivotably attached to the projection  106   ab  about the first pivot pin  112   a , the force applied by the first spring  116   a  pulls the first roller  110   a  upwards, with respect to the central hub  102  (the direction of the force is shown with an arrow along with the first roller  110   a ). Similarly, a second end of the second retracting arm  108   b  is attached to a second fixed pin  114   b  (not visible in Figs) by using a second spring  116   b  (not visible in Figs). The second spring  116   b  pulls the second end of the second retracting arm  108   b  towards the second fixed pin  114   b . Since the second retracting arm  108   b  is pivotably attached to the projection  106   ab  about the second pivot pin  112   b , the force applied by the second spring  116   b  pulls the second roller  110   b  upwards, with respect to the central hub  102 . Thus, the springs  116   a  and  116   b  help the retracting arms  108   a  and  108   b  remain in their “normal position” (i.e., pulled upwards with respect to the central hub  102 ). If a counter-force of a magnitude greater than that exerted by springs  116   a  and  116   b  is applied on the retracting arms  108   a  and  108   b , they can be moved downwards with respect to the central hub  102 . 
     The retracting arms  108   a  and  108   b  of the first projection  106   ab  and similar retracting arms of the projections  106   cd ,  106   ef , and  106   gh  are collectively referred to as the retracting arms  108 . Further, any other suitable mechanism such as a lever mechanism, spiral spring, elastic material, or a torsion spring mechanism may be used in place of the first and second springs  116 . 
     The second projection  106   cd , the third projection  106   ef , and the fourth projection  106   gh  each have similar arrangements of two retracting arms, corresponding rollers, pivot pins, fixed pins, and springs attached thereto (not numbered in  FIG.  1    for sake of simplicity). Since these arrangements are similar in construction and functioning to the arrangement of the first projection  106   ab , the first and second retracting arms  108   a  and  108   b , the first and second rollers  110   a  and  110   b , the first and second pivot pins  112   a  and  112   b , the first and second fixed pins  114   a  and  114   b , and the first and second springs  116   a  and  116   b , their description has been omitted so as not to obfuscate the present specification. Further, it should be noted that in  FIG.  1   , four projections  106   ab ,  106   cd ,  106   ef , and  106   gh  are shown for illustrative purpose only. The invention is equally applicable to any number of projections, such as two or three projections. The projections should be preferably equally spaced apart from each other. For example, two projections may be spaced apart by 180-degrees and three projections may be spaced apart by 120-degrees. In an embodiment, the central hub  102  and the retracting arms  108  are made of aluminum, stainless (heavy stainless), or plastic (ABS). The central hub  102  and the retracting arms  108  can be manufactured by injection molding, cast, or welding. In an embodiment, size of the tool  100  may of various sizes fit for the interior of the pipe to be painted. The size of the tool may be from two (2″) inches to ten (10″) inches (measured with the legs outstretched) with a preference for size to fit a pipe interior of about five (5″) oro six (6″) inch diameter. 
     The central hub  102  preferably includes an appropriate arrangement to carry a spray painting gun (not shown). For example, one or more bolts or screws  118  may be provided on the central hub  102  to firmly hold the spray painting gun in the hollow tube  104  of the central hub  102 . The operation of the tool  100  along with the system for painting (including the spray painting gun) is explained in detail in conjunction with  FIG.  5    in the forthcoming description. 
     Referring now to  FIG.  2   , a front view illustrating the tool of  FIG.  1   , when inserted inside a tubular pipe in a straight section  200  of the tubular pipe, is shown.  FIG.  3    is a side view corresponding to the front view of  FIG.  2   . Collectively referring to  FIGS.  2  and  3   , the tool  100  is inserted in a straight section  200  of a tubular pipe through its first end  202   a . A flange  204 , which is optional, is shown to be attached at the first end  202   a . In the normal position of the tool  100 , the retracting arms  108  are retracted such that the distance between the two retracting arms  108  (also referred to as the height of the tool  100 ) is maximum. When the diameter of the opening at the first end  202   a  is less than the height of the tool  100 , the retracting arms  108  may be pushed towards the central hub  102 , thereby reducing the height of the tool  100  for inserting the tool  100  through the opening at the first end  202   a . Once inserted, the force on the retracting arms  108  acts as indicated by the arrows of  FIG.  2   . Thus, the rollers  110  firmly grip an inner surface of the tubular pipe. Due to the rolling function of the rollers  110 , the tool can be moved along the straight section  200  of the tubular pipe. As shown in  FIG.  3   , the bolts (or screws)  118  assist in holding a spray painting gun (now shown) in the hollow portion formed by the hollow tube  104 . This is further explained in conjunction with  FIG.  5   . 
       FIG.  4    is a perspective view of the tool  100  of  FIGS.  1 - 3   , inserted inside the tubular pipe in a curved section  402  of the tubular pipe, in accordance with an embodiment of the present invention. As the tool  100  is moved inside the tubular pipe manually or by using an automated mechanism from the straight section  200  towards the curved section  402 , the diameter of the tubular pipe changes. Since the retracting arms  108  have an outward force acting thereon, they expand or contract as required to accommodate the change in diameter of the tubular pipe as the tool traverses inside the tubular pipe. As there are multiple retracting arms  108  that are uniformly distributed along the hollow tube  104 , the force is equally distributed. Thus, the tool  100  holds the internal surface of the tubular pipe firmly and can withstand high pressure applications of coating of the inside of the tubular pipe. 
     Referring now to  FIG.  5   , a schematic diagram showing the tool  100  of  FIG.  1    in operation, along with a system used for coating an internal surface of the tubular pipe, in accordance with various embodiments of the present invention is shown. The tool  100  is inserted in a hollow tubular pipe from its first end  202   a . The tool  100  carries therein, a spray painting system having a spray nozzle  502  (sometimes referred to as air-gun nozzle), a paint hose or pipe  504 , an air hose (not shown), and a fluid spraying mechanism  506 . The fluid spraying mechanism  506  may be a spray painting gun such as a hand spray gun or a pump-based spraying system, depending on the application for which the tool  100  is being used. In an embodiment, the spray nozzle  502  may be driven by a motor. The air hose that is embedded in the hollow tube  104  is connected to the motor to provide the motor spin. Various media may be used to coat the internal surface of the tubular pipe. For example, the spraying medium may be made of epoxy, such as liquid epoxy or internal fusion bonded epoxy (FBE), paints, amine cured glass and ceramic coatings, such as the NOVA-Plate® 325 by the Sherwin Williams Company, and the like. 
     In operation, the paint hose  504  is inserted in a paint manifold. The air hose is inserted in the hollow tube  104  of the tool  100  to make the motor spin and is firmly fitted therein by using the bolts or screws  118 . The spray nozzle  502  protrudes outside the tool  100 . The tool  100  is inserted inside the tubular pipe by adjusting the height of the tool  100  as explained earlier. Once placed inside the tubular pipe, the tool  100  expands due to the retracting arms  108 , thus adjusting to the diameter of the tubular pipe. The tool  100  is then maneuvered inside the tubular pipe by applying appropriate force on to the hose  504  in the direction of travel of the tool  100 . As discussed in the foregoing, the tool  100  adjusts itself to the varying diameters of the tubular pipe along the curved section  402  and the straight section  200  by varying its height. The fluid spraying mechanism  506  injects compressed air through the air hose and coating fluid, such as an epoxy or a paint through the paint hose  504  to the spray nozzle  502 . The spray nozzle  502  is a rotary nozzle that rotates at a very high speed (for example, at 20,000 revolutions per minute). The rotation of the spray nozzle  502  breaks up the coating fluid or atomizes it, causing the coating fluid to break up into droplets that form a spray. The spray nozzle  502  sprays the coating fluid on to the internal surface of the tubular pipe in a 360-degree pattern. When the tool is maneuvered from the first opening  202   a  to the second opening  202   b  with an appropriate linear velocity, the internal surface of the tubular pipe is uniformly coated. The tool  100  can securely hold the spraying nozzle  502 , the air hose, and the paint hose  504  without vibrating the spraying nozzle  502  while the coating operation is in progress. The painting of the interior of the pipe can occur when the tool is inserted as well as removed from the pipe. Hence all surfaces are covered with paint. In an embodiment, the tool  100  can hold an airless pump for coating of the inner surface of the tubular pipe. 
     It should be noted that the coating system including the paint hose  504  and fluid spraying mechanism  506  are shown here for illustrative purposes only and they do not limit the scope of the invention in any way. The present invention is equally applicable to various other fluid spraying mechanisms known in the art. In addition, any other system that is used for internal coating of pipes may be supported by the tool  100  of the present invention. While the invention is described utilizing a round pipe having curves, it is understood by those of skill in the art that it may be employed for pipes of different shapes. The inventive tool can be used for shapes such as square tubing, octagon, or other shapes, provided the tool is secure within the interior and appropriate force is directed towards the interior surface of the pipe to securely roll (or maneuver) the tool during use. The tool may be used for other applications than painting the interior surface of a pipe, again, providing sufficient force against the interior surface wall to securely maneuver the tool during the application (other applications include for example: cleaning and pressure washing, or use with fluids for the interior of pipe or enclosed container). 
     The embodiments of the present invention, as described herein, offer one or more of the following advantages. The tool  100  can be efficiently used for applications involving coating interiors of smaller diameter tubular pipes, such as two inches (2″) to ten inches (10″) diameter tubular pipes. The same tool  100 , depending on lengths of the retracting arms  108 , may be used with tubular pipes of different diameters. Based on the experimental results obtained from the tests carried out by the inventors, the tool  100  works best with tubular pipes having diameters in the range of six inches (6″) and eight inches (8″), with a spray gun that sprays the coating fluid at 2,000 to 4,500 psi (pounds per square inch). The tool  100  has the adjustable size feature through the pivotable arms, and can be used for tubular pipes of various dimensions, specifically two (2″), four inches (4″) and up to ten inches (10″) by either varying length of the retracting arms  108  or dimensions of the central hub  102 . As an alternate embodiment, the tool can be manufactured to fit a specific interior pipe diameter, and corresponding paint spraying mechanism. For example, the tool may be made to fit the interior of a two (2″) inch pipe such that the projections and arm assembly will maximize their extension to fit securely within the 2″ inch diameter of the pipe. Unlike other tools on the market for cleaning or painting applications of this sort, the present tool is versatile in size either through specific manufacture, or adjustment through pivotable arms to fit smaller spaces and also travel through curves and up to 90 degree angles while still painting or cleaning the surface sufficiently to pass the holiday detection tests. The tool  100  is simple in construction and is less bulky as compared to the conventional tools. Further, the tool  100  adjusts its height automatically, thereby eliminating the need for a manual intervention. Since the linear velocity of the movement of the tool  100  inside the tubular pipe can be controlled (manually or automatically), and since the tool  100  can withstand high pressure coating operations, a uniform and flawless coating can be obtained. The coating thus produced is free from the holiday effect often observed in prior art. All standard precautions when using a high pressure spray painting apparatus should be employed with the present invention. 
     The present invention has been described herein with reference to a particular embodiment for a particular application. Although selected embodiments have been illustrated and described in detail, it may be understood that various substitutions and alterations are possible. Those having ordinary skill in the art and access to the present teachings may recognize additional various substitutions and alterations are also possible without departing from the spirit and scope of the present invention, and as defined by the following claim. 
     While pins, spring, and pivots were described for use with the present tool, alternatives exist allowing the projections and arm assemblies to pivot and expand to the interior of the pipe surface. It is understood any type of means is acceptable for the function of pivotal projection and arm assemblies provided the projection/arms expand within the pipe surface and secure sufficiently to be maneuvered through the interior of the pipe while the desired application is ongoing.