Patent Publication Number: US-2012042461-A1

Title: Pipe Cleaning Apparatus

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims priority to U.S. Provisional Patent Application No. 61/374,355, filed Aug. 17, 2010, entitled “Pipe Cleaning Apparatus”, the entire disclosure of which is herein incorporated by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention generally relates to the field of pipe cleaning devices and, more particularly, to plug assemblies operative for cleaning an inner surface of heat exchanger and condenser tubing or piping. 
     2. Description of the Related Art 
     Heat exchanger systems typically have a plurality of tubes or pipes through which a liquid cooling or heating medium, such as water, flows to remove heat from, or add heat to, an industrial process or the like. Inner surface of heat exchanger tubing or piping is prone to accumulating sediment from the liquid medium. Accumulation of sediment from the liquid medium presents many problems, such as deposits and obstructions, which limit heat transfer efficiency and life expectancy of the tubing. Slime, sticks, mud, shells, calcium carbonate scale or manganese scale are examples of additional problems caused by sediment accumulation on the inside surface of tubing or piping. 
     Pipe cleaning assemblies have been developed to aid in removal of accumulated sediment. Typically, these pipe cleaning assemblies include a fin or blade arrangement attached to a body. Such pipe cleaning assembly is placed at one end of the tube to be cleaned with the fins in contact with an inner surface of the tube. High pressure water or other propelling fluid is applied to the tube to force the pipe cleaning assembly through the tube. This causes the fin or blade arrangement to move axially within the tube and, in the process, scrape the inner surface of the tube and remove obstructions and deposits along the way until the pipe cleaning assembly exits the tube. A properly cleaned inner surface of the tube yields increased heat exchanger and condenser efficiency and prolongs the life expectancy of the tubing. 
     Within the prior art, U.S. Pat. No. 3,939,519 to Muirhead is directed to a tube cleaning plug having an elongated core body and a plurality of spaced scraper discs provided along the body. The scraper discs have radial slits extending from a surface adjacent to the body to their outer periphery to define a plurality of segments. The segments are flexible to allow deflection during insertion into a pipe and passage therethrough. The slits allow for passage of propelling fluid and sediment dislodged by the scraper discs contacting the inner surface of the pipe. 
     U.S. Pat. No. 4,178,649 to Kouse et al. discloses a tube cleaning device having a plurality of scraper elements removably coupled to form a chain. Each scraper element includes a centrally-located body having a recessed portion and a protruding portion. The recessed portion is dimensioned such that it accepts the protruding portion of an adjacent scraper element. A plurality of flexible scraper elements extend radially outward from the body. A plurality of scraper elements may be coupled to form a flexible chain which may be passed through the tortuous path of a typical heat exchanger system. 
     U.S. Pat. No. 5,528,790 to Curran teaches a scraper assembly that is forced through heat exchanger tubes at high pressure for scraping deposits from an inner surface of tubes. A cylindrical body having a barrel, a head, and a tail end receives a plurality of rings spaced apart axially along the barrel. Spacer sleeves separate the rings in an alternating manner. Each ring includes a radial compression slot formed at an angle relative to the axial direction of the barrel to create a rifling effect as the scraper assembly is passed through the tube. 
     The pipe cleaning assemblies can be made from a polymeric material, as exemplified by the FLEX-DART™ pipe cleaning assembly manufactured by ITC, Inc., the assignee of this patent application. For more difficult deposits, a metal fin can be used, such as the stainless steel DART™ pipe cleaning assembly manufactured by ITC, Inc., the assignee of this patent application, and shown in  FIG. 1 . 
     Specifically,  FIG. 1  shows a prior art stainless steel DART™ pipe cleaning assembly  10  that includes a unitary plastic body  12  having a plurality of stamped metal scraper blades  14  removably attached thereto. The metal scraper blades  14  include an engagement portion  16  and a scraping blade portion  18 . Legs  20  connect the scraping blade portion  18  to the engagement portion  16 . Windows  22  are defined by the legs  20 . The scraping blade leg portion  18  is defined by three arcuate segments  24  of approximately 90° and results in a non-continuous member with a body receiving opening  26 . Finally, a tip  28  and a tail piece  30  are provided on the body  12 . Preferably, three metal scraper blades  14  are received by the body  12 . The metal scraper blades  14  are axially spaced apart from each other and circumferentially offset so that the pipe cleaning assembly  10  contacts the complete periphery of the inner surface of the pipe as it is pushed through the tube. Although the pipe cleaning assembly  10  works well, it must be preassembled which requires a substantial amount of labor costs. 
     Numerous other disadvantages are associated with the prior art designs. Prior art embodiments that utilize metal scraper blades are expensive to manufacture because of their non-circular shape, often resulting in a high manufacturing rejection rate. Furthermore, existing designs cannot be easily repaired in the field, which can further extend the downtime of a heat exchanger or condenser system. Additionally, scraper blades made from plastic or polymeric materials are often highly flexible, which causes them to deflect over sediments rather than dislodge them from the inside surface of the tube. 
     In view of the foregoing, a need exists for a pipe cleaning apparatus that can be easily assembled and repaired in the field within minimum skill and labor requirements. An additional need exists for providing a pipe cleaning apparatus that effectively removes sediments from the inner surface of heat exchanger and condenser tubes. Furthermore, there exists a need for a pipe cleaning apparatus having low manufacturing costs. 
     SUMMARY OF THE INVENTION 
     According to one embodiment, a pipe cleaning apparatus for cleaning an inner surface of tubing or piping includes a cylindrically-shaped shaft having a head provided at a first end, and a cap provided at a second end, and a plurality of scrapers provided on the shaft. Each scraper may be longitudinally spaced apart and coaxially aligned along the axial length of the shaft. The pipe cleaning apparatus may additionally include a plurality of spacers provided on the shaft in a coaxial arrangement for longitudinally spacing apart the scrapers. Each scraper desirably has a central opening extending through the scraper along its longitudinal axis and a radial slot extending from the central opening to the outer perimeter of the scraper. 
     According to another embodiment, the pipe cleaning apparatus may be adapted for insertion into a pipe. In accordance with this embodiment, each scraper desirably has an outer diameter slightly larger than an inner diameter of the pipe. In this manner, each scraper is adapted to deflect slightly toward a central axis of the scraper, such that the outer perimeter of the scraper is always in contact with the inner surface of the pipe. 
     In accordance with another embodiment of the pipe cleaning apparatus, diameter of the central opening of each scraper is preferably slightly larger than the diameter of the shaft to allow the scraper to slide along the shaft. Each spacer may have a central hole extending along a central axis of the spacer. Similar to the scraper structure, diameter of the central hole may be slightly larger than the diameter of the shaft to allow the spacer to slide along the shaft. Each scraper and spacer may be independently rotatable about the longitudinal axis of the shaft. Additionally, each spacer is desirably uniform in length to maintain the scrapers substantially equidistant to each other. 
     According to another embodiment of the pipe cleaning apparatus, the length of each scraper in the axial direction may be substantially smaller than the width in the radial direction. Desirably, the pipe cleaning apparatus may have a modular construction, such that one or more scrapers or spacers may be added or subtracted to increase or decrease the length of the pipe cleaning apparatus. 
     In one embodiment of the pipe cleaning apparatus, the shaft may be a rivet such that the cap is pressed onto the second end of the shaft. Desirably, the rivet may be made of aluminum. Each scraper may be made from a non-metallic material, such as high density polyethylene. Similarly, each spacer may be made from a non-metallic material, such as propylene. 
     Further details and advantages of the present pipe cleaning apparatus will become apparent from the following detailed description read in conjunction with the drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a pipe cleaning assembly according to a prior art embodiment; 
         FIG. 2  is a perspective view of a pipe cleaning assembly according to one embodiment; 
         FIG. 3  is an exploded view of the components of the pipe cleaning assembly shown in  FIG. 2 ; 
         FIG. 4  is a section view of the pipe cleaning assembly shown in  FIG. 2  received in a pipe; 
         FIG. 5  is a side view of the pipe cleaning assembly shown in  FIG. 2 ; 
         FIG. 6  is a top view of the pipe cleaning assembly shown in  FIGS. 2 ; and 
         FIG. 7  is a bottom view of the pipe cleaning assembly shown in  FIG. 2 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     For purposes of the description hereinafter, spatial orientation terms, if used, shall relate to the referenced embodiment as it is oriented in the accompanying drawing figures or otherwise described in the following detailed description. However, it is to be understood that the embodiments described hereinafter may assume many alternative variations and embodiments. It is also to be understood that the specific devices illustrated in the accompanying drawing figures, and described herein, are simply exemplary and should not be considered as limiting. Additionally, terms “pipe”, “piping”, “hose”, “tube”, or “tubing” may be used interchangeably in reference to an annular conduit typically utilized in heat exchanger and condenser systems. 
     Referring to the drawings in which like reference characters refer to like parts throughout the several views thereof, the present invention is generally described in terms of a pipe cleaning apparatus for use in cleaning heat exchanger and condenser systems. With reference to  FIG. 2 , a pipe cleaning apparatus  50  is illustrated in accordance with one embodiment. While pipe cleaning apparatus  50  can be alternatively referred to as a pipe cleaning assembly, a pipe cleaning dart, or a pig, one of ordinary skill in the art will understand that each of these designations refers to pipe clearung apparatus  50  described herein. 
     With reference to  FIG. 3 , and with continuing reference to  FIG. 2 , pipe cleaning apparatus  50  generally includes a plurality of scrapers  52  connected to a single cylindrical shaft  54 . Scrapers  52  are arranged in an axially-offset manner along the length of shaft  54 . Scrapers  52  are independently rotatable about the longitudinal axis of shaft  54 . While  FIGS. 2 and 3  illustrate an embodiment of pipe cleaning apparatus  50  having three scrapers  52 , one of ordinary skill in the art will understand that more or fewer scrapers  52  may be used in different embodiments of pipe cleaning apparatus  50 . In some embodiments, pipe cleaning apparatus  50  may have a modular construction where one or more scrapers  52  may be added to shaft  54  to increase or decrease, respectively, the length of pipe cleaning apparatus  50 . 
     With continuing reference to  FIG. 3 , shaft  54  has a first end  56  opposite a second end  58 . A cylindrically-shaped head  60  is connected to shaft  54  at first end  56 . A cylindrically-shaped cap  62  is connected to shaft  54  at second end  58 . Desirably, shaft  54  is an aluminum rivet where cap  62  is pressed onto second end  58  of shaft  54 . In alternate embodiments, shaft  54  may be another type of a fastener, such as a bolt having a head and a threaded end. Additionally, shaft  54  may be manufactured from materials other than aluminum. 
     As illustrated in  FIG. 3 , scrapers  52  have a generally cylindrical shape. The length of scrapers  52  in the axial direction is substantially smaller than the width in the radial direction. Each scraper  52  has a central opening  64  provided through the length of scraper  52  along the central axis. The diameter of each opening  64  is slightly larger than the diameter of cylindrical shaft  54 , allowing scrappers  52  to snugly slide on shaft  54 . Each scraper  52  includes a radial slot  66  that allows for slight compression and expansion of scraper  52 . Additionally, slot  66  enables the propelling fluid to pass between adjacent scrapers  52  of pipe cleaning apparatus  50  to flush out any loose sediment or debris dislodged from the inner surface of the tubing. Slot  66  extends from opening  64  to the outer peripheral surface of scraper  52 . Desirably, slot  66  is made slightly narrower than the diameter of opening  64  to prevent scraper  52  from separating from shaft  54 . 
     As shown in  FIG. 4 , pipe cleaning assembly  50  is adapted to be received within a tube or pipe  100 . Desirably, scrapers  52  of pipe cleaning apparatus  50  have an outer diameter D which is slightly greater than the inner diameter D′ of pipe  100 . For example, the difference between diameter D of scrapers  52  and diameter D′ of pipe  100  is on the order of several thousands of an inch, e.g., 0.005 inches. In this manner, when pipe cleaning apparatus  50  is inserted into pipe  100 , scrapers  52  deflect slightly toward the central axis. This arrangement ensures that the outer perimeter of scrapers  52  is always in contact with the inner surface of pipe  100 . 
     Referring back to  FIGS. 2 and 3 , scrapers  52  are desirably made of high density polyethylene material. In certain embodiments, it is desirable that scrapers  52  are made of non-metallic material to protect the inner surface of tubing. Scrapers  52  may have a cylindrical or slightly conical shape and may be made using a variety of different manufacturing techniques. 
     With continuing reference to  FIGS. 2 and 3 , a plurality of spacers  68  are inserted onto shaft  54  and between each scraper  52 . Each spacer  68  has a generally cylindrical shape having a central hole  70  extending along the central axis of spacer  68 . Spacers  68  are preferably equal in length, such that each scraper  52  is maintained substantially equidistant to an adjacent scraper  52 . Alternatively, spacers  68  may have different lengths to maintain scrapers  52  at different distances from each other. Spacers are preferably made of propylene material.  FIGS. 5-7  show top, side, and bottom views, respectively, of pipe cleaning apparatus  50  shown in  FIG. 2 . 
     Having described the structure of pipe cleaning apparatus  50  in accordance with one embodiment, assembly of pipe cleaning apparatus  50  will now be discussed with continuing reference to  FIGS. 2 and 3 . Initially, a scraper  52  is secured onto shaft  54  by inserting opening  64  onto second end  58  of shaft  54 . Scraper  52  is slid along shaft  54  until it abuts head  60  of shaft  54 . A spacer  68  is then secured onto shaft  54  by inserting hole  70  onto second end  58  of shaft  54 . A second scraper  52  is then inserted in a similar manner to the first scraper  52 . The second scraper  52  is slid along shaft  54  until it abuts against spacer  68 . A second spacer  68  is inserted onto shaft  54  followed by a third scraper  52 . A cap  62  is then permanently fastened onto a second end  58  of shaft  54  to hold pipe cleaning apparatus  50  together. In embodiments where a greater number of scrapers  52  is required, this installation procedure can be repeated until a requisite number of scrapers  52  are attached to shaft  54 . 
     In operation, the assembled pipe cleaning apparatus  50  is inserted in pipe  100  by inserting either the first end  56  or second end  58  of shaft  54 . High pressure propelling fluid, such as water, is supplied to pipe  100 . The pressure provided by the propelling fluid forces pipe cleaning apparatus  50  to move through pipe  100  toward an exit end with a portion of cleaning fluid passing through the slots  66  of scrapers  52 . Scrapers  52  dislodge accumulated deposits from the inner surface of pipe  100 . The dislodged deposits are then pushed along by scrapers  52  or are carried by the propelling fluid passing through slots  66 . After pipe cleaning apparatus  50  exits pipe  100 , the process can be repeated on another pipe  100 . 
     The pipe cleaning apparatus  50  is desirably assembled prior to use. However, it may also be assembled onsite, as needed. Further, the present pipe cleaning apparatus  50  permits repair of the cleaning plug assemblies onsite by replacing any damaged scrapers  52  and/or shafts  54 . Also, a number of scrapers  52  of the pipe cleaning apparatus  50  can be modified onsite. Specifically, if it is determined that three scrapers  52  do not adequately clean the pipe  100 , then additional scrapers  52  can be added to the pipe cleaning apparatus  50 . 
     Further, the present pipe cleaning apparatus  50  has a simplified construction that is easier to assemble than the previously described prior art because the orientation of scrapers  52 , relative to shaft  54 , is not important as is the case in the prior art. Additionally, scrapers  52  of the present pipe cleaning apparatus may be manufactured with higher tolerances because of their simple construction relative to embodiments described in the prior art. This minimizes the rejection rate of scrapers  52  and simplifies their manufacture compared to the prior art. 
     While an embodiment of pipe cleaning apparatus is shown in the accompanying figures and described herein in detail, other embodiments will be apparent to, and readily made by those skilled in the art, without departing from the scope and spirit of the invention. For example, while the present disclosure generally discusses the pipe cleaning assembly for use in cleaning heat exchanger and condenser piping and tubing, it is contemplated that various embodiments of the present pipe cleaning assembly may be applicable to cleaning the inner surface of pipes or tubes used in various other applications. The scope of the invention will be measured by the appended claims and their equivalents.