Abstract:
A pipeline pig that is moved by pressurized gas flow and that provides for distribution of treating liquid subsisting in the lower portion of the pipeline, having a pig body with a nose cone at a foward end thereof, centralizers affixed to the pig body by which it is supported in the pipeline, a bypass passageway within the nose cone communicating with the pipeline interior, a siphon passageway within the nose cone communicating with a lower portion of the pipeline interior and therby with any liquid subsisting therein and having an outlet end, and a venturi in communication with the siphon passageway and the bypass passageway, gas flowing through the bypass passageway serving to draw liquid from the lower portion of the pipeline through the siphon passageway whereby the liquid is discharged form the siphon passageway outlet end onto ineterior surfaces of the pipeline.

Description:
REFERENCE TO PENDING APPLICATIONS 
   This application is a divisional application taken from U.S. patent application Ser. No. 10/172,691 filed 14 Jun. 2002 now U.S. Pat. No. 6,755,916 entitled INHIBITOR DISPENSING PIPELINE PIG which title was changed to: A METHOD OF DISTRIBUTING INHIBITOR CONTAINED WITHIN A GAS PIPELINE in a post allowance amendment filed 1 Mar. 2004. 

   REFERENCE TO MICROFICHE APPENDIX 
   This application is not referenced in any microfiche appendix. 
   FIELD OF THE INVENTION 
   The invention described herein is a pipeline pig that is moved through the interior of a pipeline by the flow of pressurized gas and that provides improved distribution of treating liquids such as inhibitors subsisting in the lower portions of the pipeline 
   BACKGROUND OF THE INVENTION 
   The invention described herein is a pipeline pig that provides a method of applying a treating fluid, such as an inhibitor, within a pipeline to specific longitudinal areas along the inner wall of the pipeline and particularly to the upper interior portions of the interior wall of a pipeline. 
   Pipelines, particularly those designed to carry large volumes of gas under pressure, are customarily made of metal and usually of steel; Steel is the preferred metal for construction of a pipeline due to its inherent strength, availability and economy. However, steel is subject to corrosion as a consequence of oxidation or reaction with gasses or liquids, such as water, that is commonly encountered when large volumes of gas are delivered through a pipeline. To combat corrosion a standard technique employed by many operators of pipelines is to periodically deposit inhibitor liquid within the pipeline. The liquid can be moved by the flow of gas through the pipeline or more commonly, by the use of pipeline pigs inserted into the pipeline that are moved by the flow of gas, the pigs serving to provide a moving plunger within the pipeline that tends to sweep liquid within the pipeline before it and to therefore move the liquid through the full length of the pipeline. 
   One method of applying a treating liquid to the interior of a pipeline is called “batching” in which treating liquid is captured between two pipeline pigs that move in tandem through a pipeline pig with the treating liquid therebetween. Although this method is widely accepted and used it does not insure that the upper quadrant of the interior of a pipeline is adequately coated with or exposed to the treating liquid. 
   A second method of treating the interior cylindrical surface of a pipeline is called the “injection method.” In this method, the treating liquid is injected directly into the pipeline and is moved by gas flow to carry the liquid through the length of the pipeline. This method is costly and usually requires that treating liquids be more or less continuously injected into the pipeline. There is no direct application, in this method, of the treating liquid to the inner wall since liquid simply rests on the bottom interior surface of the pipeline as it moves along the length of the pipeline. 
   To combat these problems, the pipeline pig of this invention provides a method of distributing liquid present in the lower portion of a pipeline to the interior upper quadrant of the pipeline interior as the pig passes by the flow of gas through the length of the pipeline. 
   For background information relating to pipeline pigs that have similar uses and applications reference may be had to the following previously issued United States patents and a U.S. patent application publication: 
   
     
       
             
             
             
           
         
             
                 
             
             
               U.S. Pat. No. 
               Inventor(s) 
               Title 
             
             
                 
             
           
           
             
               2,707,934 
               Curtis 
               Pipeline Treating Plug 
             
             
               3,111,431 
               Weaver 
               Interior Pipe Coating Device 
             
             
               3,643,280 
               Powers 
               Pipeline Pigs 
             
             
               4,411,039 
               Timmins, et al. 
               Removal of Condensed Gas from 
             
             
                 
                 
               the Walls of Gas Pipelines 
             
             
               4,774,905 
               Nobis 
               Apparatus for Internally 
             
             
                 
                 
               Coating Pipes 
             
             
               5,795,402 
               Hargett, Sr. et al. 
               Apparatus and Method for 
             
             
                 
                 
               Removal of Paraffin Deposits 
             
             
                 
                 
               in Pipeline Systems 
             
             
               6,138,697 
               Horger, et al. 
               Hydrodynamic Apparatus for 
             
             
                 
                 
               Cleaning Channels and for 
             
             
                 
                 
               Monitoring Channels 
             
             
               6,263,534 
               McCann, et al. 
               Delivery Device 
             
             
               US2001/0017147 
               Gazewood 
               Method for Jetting a Fluid 
             
             
                 
             
           
        
       
     
   
   BRIEF SUMMARY OF THE INVENTION 
   The invention herein is a pipeline pig that is moved through the interior of a pipeline by the flow of pressurized gas and that provides for improved distribution of treating liquid, such as an inhibitor, subsisting in the lower portion of the pipeline. The pipeline pig has a longitudinal pig body having a forward end and a rearward end. Forward and rearward centralizers are affixed to the pig body by which it is supported centrally in the pipeline and by which it is moved by gas flow through the pipeline. These centralizers are preferably in the form of elastameric cups or disks, each having an external circumferential surface that closely conforms to the internal circumferential surface of the pipeline. 
   A bypass passageway is provided through the pig body that communicates with the pipeline interior rearward end. A separate siphon passageway, communicates with a lower portion of the pipeline interior, the siphon passageway being preferably positioned adjacent the front end of the pig body. 
   A venturi is supported by the pig body in communication with the siphon passage and with the bypass passageway. A flow of gas through the bypass passageway serves to draw liquid through the siphon passageway and, employing the Bernoulli effect, the liquid from the siphon passageway is discharged onto an upper portion or upper portions of the interior pipeline wall. In this way, as the pipeline pig is moved through the interior of a pipeline, liquid is moved by the application of Bernoulli&#39;s law to be sprayed onto the upper interior portion of the pipeline. 
   The method of distributing liquid present in the lower portion of a gas pipeline to the interior upper surface of the pipeline includes the steps of passing a pig having a venturi therein that is activated by gas pressure taken from a rearward end portion of the pig siphoning liquid from the lower interior portion of the pipeline by venturi action, and distributing the siphon liquid to the pipeline upper interior surface. 
   A better and more complete understanding of the invention will be obtained from the following description of the preferred embodiments, and the claims, taken in conjunction with the attached drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is an elevational cross-sectional view of a pipeline pig that encompasses the principles of this disclosure. The pipeline pig of  FIG. 1  has a first fluid reservoir within the interior of the pig body and a second, forward reservoir in the nose cone portion of the pig for purposes that will be described in detail subsequently. 
       FIG. 2  is an elevational cross-sectional view of a pipeline pig as in  FIG. 1  but in the embodiment wherein only a body reservoir is employed. 
       FIG. 3  is a cross-sectional view taken along the line  3 — 3  of FIG.  1 . This view is taken through a portion of the rearward cup of the pipeline pig and shows the passageway for bypass gas flow to enter the rearward end of the pig body. 
       FIG. 4  is an elevational cross-sectional view taken along the line  4 — 4  of  FIG. 1  showing the midsection of the pipeline pig body. 
       FIG. 5  is an elevational cross-sectional view taken along the line  5 — 5  of  FIG. 1  showing a cross-sectional view of a portion of the nose cone and of the area that forms the forward reservoir.  FIG. 5  also shows a secondary channel that draws fluid from the forward reservoir for ejection by the spray nozzle. 
       FIG. 6  is an elevational front view of the pipeline pig as taken along the line  6 — 6  of  FIG. 1  showing the nose cone and the spray nozzle in the nose cone through which liquid is ejected by bypass gas flow. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   It is understood that the invention herein is not limited to the details of construction and arrangement of parts illustrated in the accompanying drawings. The invention is capable of other embodiments and of being practiced or carried out in a variety of ways. The phraseology and terminology employed herein are for the purpose of description and not limitation. 
   The drawings illustrate inhibitor dispensing pipeline pigs that have the following components: 
   
     
       
             
             
             
           
         
             
                 
                 
             
           
           
             
                 
               10 
               cylindrical body 
             
             
                 
               12 
               rearward end 
             
             
                 
               14 
               forward end 
             
             
                 
               16 
               rearward flange 
             
             
                 
               18 
               forward flange 
             
             
                 
               20 
               rearward cup 
             
             
                 
               22 
               forward cup 
             
             
                 
               24 
               cup-shaped recess 
             
             
                 
               26 
               circumferential lip portion 
             
             
                 
               28 
               rearward radial disc 
             
             
                 
               30 
               circumferential edge 
             
             
                 
               32 
               thick inner body portion 
             
             
                 
               34 
               inlet passageway 
             
             
                 
               36 
               inlet end of passageway 
             
             
                 
               38 
               cup-shaped recess of cup 20 
             
             
                 
               40 
               cup lip portion 
             
             
                 
               42 
               forward radial disc 
             
             
                 
               44 
               peripheral edge 
             
             
                 
               46 
               nose cone 
             
             
                 
               46A 
               nose cone with reservoir 
             
             
                 
               48 
               cylindrical portion 
             
             
                 
               50 
               siphon passageway 
             
             
                 
               52 
               inlet end of 50 
             
             
                 
               54 
               opposite end 50 
             
             
                 
               56 
               nozzle opening 
             
             
                 
               58 
               gas bypass passageway 
             
             
                 
               58A 
               forward portion of 58 
             
             
                 
               60 
               gas passageway exit 
             
             
                 
               62 
               counter weight 
             
             
                 
               64 
               interior of pig body 10 
             
             
                 
               66 
               reservoir 
             
             
                 
               68 
               second reservoir 
             
             
                 
               70 
               siphon tube 
             
             
                 
               72 
               open lower end 
             
             
                 
               74 
               inlet tube 
             
             
                 
               76 
               inlet end of 74 
             
             
                 
               78 
               outlet end of 74 
             
             
                 
                 
             
           
        
       
     
   
   The first embodiment to be described is the simpler of the two illustrated embodiments—that is, it employs only a single body fluid cavity and is illustrated in elevational cross-sectional view in FIG.  2 . The cross-sectional views of  FIGS. 3 ,  4  and  6  are applicable to the embodiment of FIG.  2 . The pipeline pig of  FIG. 2  includes a longitudinal cylindrical body  10  that is preferably made of a rigid material, such as of a metal pipe. Body  10  has a rearward end  12  and a forward end  14 . Positioned at the pig body rearward end  12  is a rearward cup generally indicated by the numeral  20  and in like manner positioned adjacent the body forward end  14  is a forward cup generally indicated by the numeral  22 . Cups  20  and  22  are preferably made of elastameric material, such as a tough plastic or rubber. Urethane is a commonly used material for pipeline pig cups. Rearward cup  20  has a circumferential cup shaped recess  24  in the rearward surface that provides a flexible circumferential lip portion  26 . Cup  20  is configured such that the force of gas flow through a pipeline pushing on the rearward end of the cup will tend to expand the circumferential lip portion  26  into sealing engagement with the pipeline interior cylindrical surface (not shown) so that the pig is moved by fluid flow through the pipeline. 
   Positioned between rearward cup  20  and rearward flange  16  is a rearward radial disk  28  that is also preferably made of tough elastameric material. Disk  28  has an outer circumferential edge  30  that engages the interior wall of a pipeline and serves in a squeegee action to move any fluid in the pipeline with the pig as it is forced through the pipeline by gas flow. 
   Rearward cup  20  has a thick inner body portion  32  having formed therein a rearward inlet passageway  34  that communicates at one end with the interior of pig body  10  and at the inlet end  36  with the lower interior of a pipeline (not shown) in which the pig passes. The function of inlet passageway  34  is to permit gas to pass therethrough and to carry with it any fluid captured by the gas flow from the lower interior of a pipeline. 
   Forward cup  22  is configured similar to rearward cup  20  and has a cup-shaped recess  38  that provides a circumferential forward cup lip portion  40  that is expanded outwardly by the force of gas flow to engage the interior of a pipeline in which the pig passes so that the pig is moved through the pipeline. Further, forward of and adjacent to forward cup  22  is a forward radial disk  42  that has a circumferential peripheral edge  44  that engages the interior wall of a pipeline. Disk  42  serves to move fluid in advance of the pipeline pig as it moves through a pipeline. 
   Secured to the front of pig body  10  is a nose cone  46  that is preferably formed of elastameric material and has a central reduced diameter cylindrical portion  48  received in the forward end  14  of pig body  10  by which the nose cone is secured to the pig body. A radially extended portion of the nose cone serves to capture and hold in place forward radial disk  42 . 
   Formed in the nose cone is a siphon passage  50  having an inlet end  52  in communication with the lower interior of a pipeline (not shown) in which the pig moves. The opposite end  54  of siphon passageway  50  is an outlet end that communicates with a nozzle opening  56  formed in the nose cone. 
   Formed in nose cone  46  is a gas bypass passageway  58  having a forward portion  58 A that surrounds siphon passageway  50 . This arrangement provides an annular gas passageway exit  60  at the outer end  54  of siphon passageway  50 . 
   Since the pipeline pig described up to this point is essentially symmetrical around an axis of pig body  10  and since it is important that fluid that is distributed by the pipeline pig is oriented in an upward direction to impinge upon an upper interior quadrant of the pipeline interior circumferential wall, it is important that the nozzle opening  56  be oriented upwardly. For this reason there is affixed to pig body  10  a counterweight  62  that is preferably made of metal or is otherwise heavy so that the pig body will not rotate as it moves through a pipeline but will maintain an axial orientation relative to gravitational force to axially point the nozzle opening  56  in an upwardly inclined orientation. 
   The method of operation of the embodiment of  FIGS. 2 ,  3 ,  4  and  6  will now be described. When the pipeline pig is positioned in a pipeline that has treating fluid, such as a rust inhibitor or corrosion inhibitor liquid therein, the pig is moved by gas flow through the pipeline. As it moves through the pipeline the pig, and particularly radial disks  28  and  42 , are configured to move liquid forward in advance of the pig so that the liquid will be carried from one area to another within the pipeline. As the pig moves through a pipeline and pushes liquid along ahead of it, some of the pressurized gas from the rearward end of the pipeline pig flows through rearward inlet  34 , through the interior  64  of pig body  10  and out through bypass passageway  58  and  58 A. This gas flow surrounds siphon passageway  50  and draws liquid within the lower interior portion of the pipeline into inlet end  52  of siphon passageway  50 . This is the application of what is commonly referred to as the Bernoulli principle. The Bernoulli principle states a relationship between internal fluid pressure and fluid velocity, essentially a statement of the conservation of energy that has, as a consequence, the application of a reduced pressure at the outer end  54  of siphon passageway  50  to thereby draw liquid from within this siphon passageway and carry it with the gas passing outwardly through annular gas passageway exit  60  so that a spray of liquid is formed that is ejected from nozzle opening  56  to cover an upper interior segment of the pipeline interior cylindrical wall (not shown). 
   The inlet  36  of rearward passageway  34  is preferably placed, as illustrated in  FIGS. 2 and 3 , close to the interior bottom of a pipeline through which the pig moves so that any liquid within the pipeline, rearwardly of rear cup  20 , tends to be drawn in by gas flow. This liquid collects within the interior  64  of body  10  so that the interior body forms a reservoir  66  that carries liquid with it. Reservoir  66  functions as a source of liquid that is available in the event the pipeline pig passes an area that it is otherwise void of liquid. Thus the provision of an interior reservoir within the body of the pipeline pig helps insure more consistent and even distribution of treating liquid to the upper interior portion of a pipeline interior wall. 
     FIG. 1  taken in conjunction with the cross-sectional views of  FIGS. 3 through 6 , shows an alternate embodiment of the invention in which the same or equivalent elements have the same numbers as in  FIG. 2  but in all respects the arrangement of  FIG. 1  is the same as  FIG. 2  except that  FIG. 1  provides, in addition to the first reservoir  66  within the confines of body  10 , a second reservoir  68  that is formed within the interior of a nose cone  46 A. Nose cone  46 A is essentially identical to nose cone  46  of  FIG. 2  except for the provision of the second reservoir area  68 . Further, the siphon passageway  50  includes a siphon tube  70  that has an open lower end  72  that communicates with second reservoir  68  formed in the nose cone. 
   An additional element in  FIG. 1  compared to  FIG. 2 , is an inlet tube  74  positioned within second reservoir  68 . Inlet tube  74  has an inlet end  76  (see  FIG. 5 ) that extends through the outer circumferential wall of the nose cone that forms second reservoir  68 , and an outlet end  78  that communicates with second reservoir  68 . 
   Operation of the Embodiment of FIGS.  1  Through  6   
   The liquid distribution pig of  FIG. 1  compared to that of  FIG. 2  functions in substantially the same way except that the liquid to be distributed on the interior surface of a pipeline through which the pig passes is primarily drawn from second reservoir  68  by the Bernoulli action of gas flowing through the forward portion  58 A of bypass passageway  58  and out the annular gas passageway  60 , drawing fluid from within second reservoir  68 . Liquid is forced into second reservoir  68  by the build up of liquid in front of forward radial disk  42 . As liquid is drawn by the Bernoulli action from second reservoir  66 , reduced pressure in the reservoir is created that draws fluid upwardly through fluid inlet  74  (seen in FIG.  5 ). 
   The advantage of the embodiment  FIG. 1  compared to that of  FIG. 2  is that a second reservoir is added within the pig so that if areas of a pipeline are encountered wherein no residual liquid treating resides in a lower portion of the pipeline there is more likelihood that the interior of the pipeline-will be covered by the spray of protective liquid taken from either first reservoir  66  or second reservoir  68 . 
   The invention is illustrated and described with a single siphon spray however it is easy to see that more than one such siphon spray may be arranged in the nose cone if desired. 
   The invention that has been described wherein the pig (whether the embodiment of  FIG. 1  or  FIG. 2 ) is operated by itself within a pipeline. Another method of operation of the pipeline pig described herein is to run the pig in tandem with a following second pipeline pig so that the second pipeline pig functions more or less as a piston to force liquid from within the pipeline into the fluid dispensing pig to better distribute the liquid onto the interior wall of the pipeline. 
   Important features of this invention include the provision of an injection method in the form of a pipeline pig that can be inserted into a pipeline and driven by gas pressure so that bypass flow creates siphon action drawing liquid located in the bottom portion of a pipeline and ejecting the liquid through a spray nozzle directed to the upper area of the inner pipeline wall. When the pipeline pig of this invention is used as a front element of a two pig batching process, improved action may be achieved. Further, the nozzle of the pipeline pig of this invention may be positioned in any location around the front of the pig and a plurality of nozzles may be used so that thereby a complete 360° coating application of a protective fluid onto the internal cylindrical wall of a pipeline may be attained. 
   While the invention has been described with a certain degree of particularity, it is manifest that many changes may be made in the details of construction and the arrangement of components without departing from the spirit and scope of this disclosure. It is understood that the invention is not limited to the embodiments set forth herein for purposes of exemplification, but is to be limited only by the scope of the attached claims, including the full range of equivalency to which each element thereof is entitled.