Abstract:
Methods and apparatus for applying a uniform application of an appropriate quantity of pipe dope to the internal threads of a pipe. In general, the preferred apparatus includes a supply of pipe dope and a centrifugal applicator for evenly applying the pipe dope to internal threads. The system also includes a dosing system to regulate the distribution of pipe dope by dispensing a consistent volume of pipe dope at each application. Potential advantages of the preferred embodiments include the repeatability and consistency of amount of pipe dope on pipe threads (e.g. thickness).

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
         [0001]    None.  
         STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT  
         [0002]    Not Applicable.  
         BACKGROUND OF THE INVENTION  
         [0003]    The invention relates to threaded pipe connections and the like. More particularly, the invention relates to applying a lubricating material, such as pipe dope, to the internal threads of a pipe.  
           [0004]    In the oil and gas production industry, threaded pipe connections are often used. Special types of lubricant compositions are used for application between the male and female parts of these threaded tubular connections. The use of a pipe thread dope, or “pipe dope” as it has been called, may be required to provide a more stable joint. Pipe dope is a paste-like material that is applied to clean internal pipe threads just prior to joint assembly and provides three basic benefits to a threaded pipe joint. First, it lubricates the threads to ease assembly. Second, it acts as a sealant that enhances the gas-tightness or fluid-tightness of the resulting joint. And third, it hardens or cures to effectively cement and stabilize the joint.  
           [0005]    The process of applying pipe dope has basically not changed since its original utilization. Pipe dope is commonly packaged in tins, or cans, of varying size, so one may purchase a quantity that is appropriate to the task at hand. The common method of applying pipe dope is to acquire a portion of the dope from the tin with the brush, and apply the dope to internal pipe threads by brushing. This method does not, however, assure a uniform application of the dope, either over the threads of one fitting or from joint to joint. Also, the amount of dope used is not regulated or controlled, so too much or too little dope may be used. Each of these situations may compromise the quality, durability, and reliability of the resulting threaded pipe joint. For example, too little pipe dope on the threads may result in increased friction in the threads during spinning, which may cause galling of the threaded surface. Conversely, too much pipe dope on the threads may result in pollution of the system (e.g. excess pipe dope may fall into the drillstring).  
           [0006]    In conventional methods, the quality of a threaded pipe joint is highly dependent upon the skill or craftsmanship of the user in applying the pipe dope. Thus, an apparatus to provide a uniform application of an appropriate quantity of pipe dope will greatly benefit the quality of threaded pipe joints.  
         BRIEF SUMMARY OF THE PREFERRED EMBODIMENTS  
         [0007]    The disclosed embodiments overcome the various deficiencies of the prior art by providing a method and apparatus for applying a uniform application of an appropriate quantity of pipe dope to the threads formed on the inside diameter of a pipe. In general, the preferred apparatus includes a supply of pipe dope and a centrifugal applicator for evenly applying the pipe dope to internal threads. The system also includes a dosing system to regulate the distribution of pipe dope by dispensing a consistent volume of pipe dope at each application. Potential advantages of the preferred embodiments include the repeatability and consistency of amount of pipe dope on pipe threads (e.g. thickness).  
           [0008]    In one embodiment, an apparatus for applying a uniform coating of pipe dope to the internal threads of a pipe includes a supply of pipe dope, a dosing system adapted to draw a predetermined amount of pipe dope from the supply, and a centrifugal applicator adapted to receive the predetermined amount of pipe dope and adapted to use centrifugal force to apply the dope to the internal pipe threads.  
           [0009]    In an alternative embodiment, an apparatus includes a container having the lubricant contained within, a dosing device in fluid communication with the container, an applicator drum in fluid communication with the dosing device, and a motor connected to the applicator drum. The applicator drum preferably has a plurality of holes disposed thereon in a pattern containing at least four rows of holes extending the length of the drum, where the holes in each row are spaced substantially equidistant apart and where the rows are spaced substantially equidistant apart. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]    For a more detailed description of the preferred embodiments of the present invention, reference will now be made to the accompanying drawings, wherein:  
         [0011]    [0011]FIG. 1 is a schematic of one embodiment of a lubrication assembly at a first phase of operation;  
         [0012]    [0012]FIG. 2 is a schematic of the lubrication assembly of FIG. 1 at a second phase of operation;  
         [0013]    [0013]FIG. 3 is a schematic of the lubrication assembly of FIG. 1 at a third phase of operation;  
         [0014]    [0014]FIG. 4 is a schematic of the lubrication assembly of FIG. 1 at a fourth phase of operation;  
         [0015]    [0015]FIGS. 5 a - 5   d  are partial sectional schematics of FIGS.  1 - 4  illustrating the process of applying lubrication.  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0016]    In the description that follows, like parts are marked throughout the specification and drawings with the same reference numerals, respectively. The drawing figures are not necessarily to scale. Certain features of the preferred embodiments may be shown exaggerated in scale or in somewhat schematic form and some details of conventional elements may not be shown in the interest of clarity and conciseness. The present invention is susceptible to embodiments in different forms. There are shown in the drawings, and herein will be described in detail, specific embodiments of the present invention with the understanding that the present disclosure is to be considered an exemplification of the principles of the invention, and is not intended to limit the invention to that illustrated and described herein. It is to be fully recognized that the different teachings of the embodiments discussed below may be employed separately or in any suitable combination to produce the desired results.  
         [0017]    In particular, various embodiments of the present invention provide a number of different methods and apparatus for using centrifugal force to apply a viscous material to a cylindrical surface. The concepts of the invention are discussed in the context of applying pipe dope to pipe threads but the use of the concepts of the present invention is not limited to pipe doping applications and may find utility in other coating applications, both within oilfield technology and other areas to which the concepts of the current invention may be applied.  
         [0018]    Certain terms are used throughout the following description and claims to refer to particular system components. As one skilled in the art will appreciate, components may be referred to by different names. This document does not intend to distinguish between components that differ in name but not function. In the following discussion and in the claims, the terms “including” and “comprising” are used in an open-ended fashion, and thus should be interpreted to mean “including, but not limited to . . . . ” The term “internal threads” refer to the female threads cut into the end of a length of pipe. The terms “lubricant,” “pipe thread dope,” “pipe dope,” and “thread compound” are interchangeable and describe a material that is capable of sealing and/or lubricating a pipe joint. In addition, reference to the terms “left” and “right” are made for purposes of ease of description. It should be appreciated that the scope of the invention is only limited by the claims and not by this description.  
         [0019]    Referring initially to FIG. 1, lubrication assembly  100  includes a lubricant supply  110 , a dosing system  120 , and a centrifugal applicator  130 . In general operation, dosing system  120  draws a predetermined amount of lubricant from supply  110 . Upon activation, centrifugal applicator  130  takes the predetermined amount of lubricant from supply  110  and distributes the lubricant on internal threads  50 . The controlled dosing of the lubricant coupled with the even distribution of lubricant on the threads allows the preferred embodiments to greatly improve the repeatability and consistency of lubricating threaded connections.  
         [0020]    Lubrication assembly  100  may be configured for handheld use by a single operator or may preferably be integrated into an automated pipe handling or iron roughneck system so that the threaded connections are automatically lubricated. The preferred assembly may be powered by any convenient power source, such as pneumatic, hydraulic, and electrical power. As an example of one embodiment, lubrication assembly  100  will be described as a handheld, pneumatic system, but it is understood that the embodiment described is not the only embodiment contemplated and the features described may take the form of other embodiments.  
         [0021]    FIGS.  1 - 4  depict one embodiment of an exploded lubrication assembly  100  at four different time points. Referring initially to FIGS. 1 and 5 a , lubrication assembly  100  is shown at a first time point prior to lubrication. Lubrication assembly  100  preferably includes a pipe dope container  10 , a dosing device  20 , a drum  30 , and a motor  40 . Pipe dope container  10  preferably includes a gas part  12  and a pipe dope part  13  filled with a pipe dope  23 . Pipe dope container  10  may be any container suitable for holding pipe dope  23 , including, but not limited to, a bucket and a tank. In some embodiments, pipe dope container  10  is pressurized.  
         [0022]    Dosing device  20  preferably includes a nozzle  21 , a pipe dope side  22 , a piston  24 , a piston rod  25 , a gas part  26 , a cam  27 , a cam valve  28 , and a dose adjust limit pin  29 . Cam  27  is preferably located on the end of piston rod  25 . As shown in FIG. 1, piston  24  is in an extended position and the stroke, or amount of predetermined pipe dope  23 , is limited by dose adjust limit pin  29 . In some embodiments, the stroke is varied in order to adjust the amount of pipe dope  23  to be distributed.  
         [0023]    Drum  30  preferably includes a collection area  32  and a plurality of distribution holes  34  in its walls  33 . Distribution holes  34  are preferably spaced substantially equidistant apart from each other and arranged in rows  36  that span along the width and length of the walls. Preferably, drum  30  has at least 4 rows  36  of ten holes  34 . In a preferred embodiment, distribution holes are {fraction (1/16)}″ in diameter and are spaced ¼″ apart. During lubrication, drum  30  is preferably located in opening  50 , surrounded by female pipe threads  52 .  
         [0024]    Motor  40  is preferably an air motor  42 , such as are known in the art and are used for high-speed rotating hand tools such as grinders. Air motor  42  preferably includes a fan (not shown) connected to a shaft  44 . Shaft  44  is preferably connected to drum  30 .  
         [0025]    To better describe the operation of lubrication assembly  100 , lubrication assembly  100  can be described as including three circuits, namely: (1) a high pressure gas circuit  140 ; (2) a low pressure gas circuit  150 ; and (3) a pipe dope circuit  160 . The gas utilized in these circuits is preferably any inert gas or air. The high pressure gas circuit includes a gas supply  62 , a trigger valve  64 , dosing device  20 , motor  40 , and a pressure reducing valve  66 . Gas supply  62  is preferably connected to trigger valve  64 , which is preferably connected to gas side  26  of dosing device  20 . Gas side  26  is preferably connected to cam valve  28  through cam  27 . Cam valve  28  is preferably connected to air motor  42  and pressure reducing valve  66 .  
         [0026]    In the low pressure gas circuit, pressure reducing valve  66  is connected to a check valve  68 , which is in turn connected to a manual relief valve  72 . Manual relief valve  72  is preferably connected to gas part  12  of pipe dope container  10 . In a preferred embodiment, manual relief valve  72  is used to release excess pressure in pipe dope container  10 .  
         [0027]    In the pipe dope circuit, pipe dope part  13  of pipe dope container  10  is connected to a low pressure check valve  74 . Low pressure check valve  74  is connected to high pressure check valve  75  and nozzle  21 , located on the pipe dope side  22  of dosing device  20 .  
         [0028]    Referring now to FIGS. 2 and 5 b , lubrication assembly  100  is shown at a second phase of operation, namely at the beginning of lubrication. In order for lubrication to begin, an operator pushes trigger valve  64  and holds trigger valve  64  for a desired amount of time. This maneuver causes gas pressure to flow into gas side  26  of dosing device  20 . Piston  24  creates high pressure in pipe dope side  22  of dosing device  20 . High pressure check valve  75  is open, which allows piston  24  to force pipe dope  23  in pipe dope side  22  out of dosing device  20  through nozzle  21 . In the present embodiment, piston  24  forces all of pipe dope  23  out of dosing device  20 . Pipe dope  23  then preferably passes through high pressure check valve  75  to a drum nozzle  31 . Drum nozzle  31  directs pipe dope  23  into collection area  32  of drum  30 . As shown in FIGS. 2 and 5 b , a pool  23   a  of pipe dope  23  is formed in collection area  32 .  
         [0029]    Simultaneously, gas is flowing through pressure reducing valve  66  to gas part  12  of pipe dope container  10 . This gas creates a low pressure build up in pipe dope container  10 .  
         [0030]    Referring now to FIGS. 3 and 5 c , lubrication assembly  100  is shown at a third phase of operation, during application of the lubricant. As piston  24  forces pipe dope  23  out of dosing device  20 , piston  24  moves to the left, as indicated by the arrow. Consequently, cam  27  also moves to the left and moves cam valve  28  to its open position. With cam valve  28  open, high pressure gas is allowed to flow to air motor  42 . Gas forces the blades of the fan (not shown) to turn, which in turn causes shaft  44  to rotate, as indicated by the arrow. In this embodiment, the speed that shaft  44  rotates is dependent upon a variety of factors including the consistency of pipe dope  23 , the size of pipe threads  52 , and the distance between lubrication assembly  100  and pipe threads  52 .  
         [0031]    When shaft  44  rotates, drum  30  rotates and pipe dope  23  is discharged through the plurality of distribution holes  34  via centrifugal force. FIG. 5 c  shows droplets  23   b  of pipe dope  23  suspended in opening  50 , which will deposit onto the surface of female pipe threads  52 .  
         [0032]    Referring now to FIGS. 4 and 5 d , lubrication assembly  100  is shown at a fourth phase of operation, i.e. when lubrication is complete. As shown on FIG. 5 d , pipe dope  23  has thoroughly coated the surface of female pipe threads  52 . The operator has released trigger valve  64  at this point. Because the gas supply is disconnected, gas pressure from the high pressure circuit is released through trigger valve  64 . Air motor  42  subsequently stops rotating. Low gas pressure pushes pipe dope  23  from pipe dope part  13  through low pressure check valve  74  to pipe dope side  22  of dosing device  20 . In this embodiment, pipe dope  23  does not flow to drum  30  because high pressure check valve  75  does not open by low pressure. The pipe dope  23  flowing into pipe dope side  22  pushes piston  24  to the right (as indicated by the arrow) until piston rod  25  is stopped by dose adjust limit pin  29 . During this time, cam  27  preferably releases cam valve  28  to its closed position.  
         [0033]    While the lubrication assembly of the present invention has been described in terms of a manually operated device, the lubrication assembly may alternately be machine operated, e.g. by a robotic arm. A potential benefit of having the device be machine operated is that the operator does not need to be on the drill floor during lubrication; rather, the operator may control the lubrication from a remote location. For example, a lubrication assembly could be integrated into an automatic pipe handling or pipe racking system so that the pipe joints are automatically lubricated as they are being moved into position on the drill floor. Similarly, a lubrication assembly could be integrated into a top drive system so that the pipe joint can lubricated as pipe is being run into the hole. Systems such as these could eliminate the need for personnel either on the drill floor or the monkey board applying lubricant to pipe joints during operations.  
         [0034]    While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and description. It should be understood, however, that the drawings and detailed description thereto are not intended to limit the invention to the particular form disclosed, but on the contrary, the intention is to cover all modifications, equivalents and alternatives falling within the spirit and scope of the present invention as defined by the appended claims.