Abstract:
A method of providing access to the interior of a cross-line that intersects with a primary pipeline of equal or greater diameter, including the steps of attaching a branch fitting to the exterior of the primary pipeline on the side thereof opposite the point of intersection of the cross-line, affixing a full opening valve to the branch fitting, securing a hot tap machine to the valve, by use of the hot tap machine, cutting an opening in the primary pipeline diametrically opposite of the cross-line and of a diameter at least equal to the internal diameter of the cross-line, and removing the hot tap machine leaving an access through the valve and diametrically through the primary pipeline into the interior of the cross-line.

Description:
REFERENCE TO PENDING APPLICATIONS 
   This application is not based upon any pending domestic or international patent applications. Further, the application is not related to any federally sponsored research or development. 
   REFERENCE TO MICROFICHE APPENDIX 
   This application is not referenced in any microfiche appendix. 
   BACKGROUND OF THE INVENTION 
   I. Field of the Invention 
   This invention relates to a system and method of providing access to the interior of a branch pipeline, referred to as a “cross-line” that intersects with a main pipeline of equal or greater diameter. 
   II. Description of the Prior Art 
   Pipelines are used in all parts of the world for the transportation of hydrocarbon products including primarily natural gas and crude oil. These commodities are exceedingly valuable and, in fact, indispensable to the modern standard of living enjoyed throughout the world. However, in addition to being valuable, they are also hazardous. Such hazards include danger to life as can be a consequence of explosions or fires from leaked oil or gas products and, in addition, these products can be harmful to the environment. For these reasons, it is important that pipelines be periodically inspected and/or evaluated for proper repair and maintenance. Pipelines are usually buried under the earth&#39;s surface to protect them against hazards that would exist if they were laid on the earth&#39;s surface. In addition, due to the increased amount of offshore oil and gas exploration, many pipelines today are laid at the bottom of an ocean, that is, on the ocean floor. For these reasons, the exterior surfaces of pipelines are not readily available for visual inspection. As a consequence, the most economical and effective way of inspecting pipelines is by transmitting pigs that are moved through the pipelines by fluid flow, that is, by the flow of natural gas or crude oil. For background information as to the application and use of pipeline pigs, reference may be had to an article entitled “Fundamentals of Pipeline Pigging”, authored by Burt VerNooy, appearing in  Pipeline Industry , September/October 1980, published by the Gulf Publishing Company of Houston, Tex. 
   A particular problem is encountered with the use of pipeline pigs for inspecting cross-lines, that is, pipelines that interconnect between other and usually, larger diameter pipelines. While primary pipelines may extend for miles or even hundreds of miles, cross-lines are typically of much shorter length, such as a few hundred feet up to a few miles. It is sometimes difficult and always expensive to install pig launching and receiving facilities for such cross-lines. 
   The term “cross-line” as used herein includes a pipeline that interconnects between other pipelines, as above stated, and also branch lines, that is, a smaller diameter pipeline that extends from a main pipeline that does not necessarily connect to another main pipeline but that connects such as to a storage facility, a processing plant or the like. Thus, “cross-lines” herein includes branch lines. 
   For additional background information relating to this invention, reference may be had to the following previously issued United States patents. 
   
     
       
             
             
             
           
         
             
                 
             
             
               U.S. Pat. No. 
               Inventor 
               Title 
             
             
                 
             
           
           
             
                 408,826 
               Conroy 
               Cross For Gas Mains or Pipes 
             
             
               1,825,034 
               Weatherhead, Jr. 
               Sectional Pipe Coupling 
             
             
               2,546,502 
               Harrington 
               Means For Incorporating 
             
             
                 
                 
               Solid Fat In Liquid Fatty Mixtures 
             
             
               2,563,244 
               Holicer 
               Fluid Control Mechanism 
             
             
               2,913,259 
               Rings 
               Sidebranch Fitting For Main 
             
             
                 
                 
               Supply Pipe 
             
             
               3,135,278 
               Foord et al. 
               Loading Pipeline Pigging 
             
             
                 
                 
               System and Method 
             
             
               3,373,452 
               Watts 
               Manifold Assembly For Hot and 
             
             
                 
                 
               Cold Water Faucet Pairs Arranged 
             
             
                 
                 
               Back to Back 
             
             
               3,510,156 
               Markowz 
               Device For Transmitting Flows 
             
             
               3,766,947 
               Osburn 
               Fluid Tight Closure 
             
             
               4,579,484 
               Sullivan 
               Underwater Tapping Machine 
             
             
               4,708,372 
               Arima et al. 
               Cross Piping Construction 
             
             
               4,880,028 
               Osburn et al. 
               Completion Machine 
             
             
               5,439,331 
               Andrew et al. 
               High Pressure Tapping Apparatus 
             
             
               5,678,865 
               Anderson 
               Tank Tee Unit 
             
             
               5,967,168 
               Kitani et al. 
               Method of Connecting Branch Pipe 
             
             
               6,196,256 
               Klampfer 
               Manifold 
             
             
                 
             
           
        
       
     
   
   BRIEF SUMMARY OF THE INVENTION 
   The invention herein provides methods, apparatus and systems for providing access to the interior of a cross-line that intersects with a main pipeline of equal or greater diameter. The method includes the steps of first attaching a side outlet fitting to the exterior of the main pipeline on the side thereof diametrically opposite the point of intersection of the cross-line. A side outlet may be attached by welding to the exterior of the main pipeline a saddle-type device having a portion that fits against the exterior wall of the pipeline with an integral branch fitting. After a side outlet fitting is welded to the main pipeline, a full opening valve is affixed to the outlet fitting. The typical side outlet fitting is of the type having a flange. A full open valve can be affixed to the flange fitting. 
   A hot tapping system is then affixed to the valve. The following two U.S. patents illustrate and describe apparatus and systems that can be used to tap a pipeline under pressure.
         1. U.S. Pat. No. 4,579,484 entitled “Underwater Tapping Machine”, Sullivan, issued Apr. 1, 1986;   2. U.S. Pat. No. 5,439,331 entitled “High Pressure Tapping Apparatus, Andrew et al, issued Aug. 8, 1995”       

   In the present case, such hot tapping system is applied to the exterior of the valve and with the valve open, the hot tapping system can extend through it to cut an opening in the sidewall of the main pipeline. While in some instances it may be necessary to cut an opening in the pipeline that is only as large as the interior diameter of the cross-line, nevertheless, for practical purposes, it is normally desirable that an opening be cut in the sidewall of the main pipeline substantially equal to its internal diameter. 
   After an opening is cut in the wall of the main pipeline the hot tap machine is removed and equipment can then be attached to the valve for use in inserting inspection pigs into the pipeline. As a practical step, after the hot tap machine has been employed, a pig launcher may be affixed to the valve. Thereafter, with the valve open, a pig can be launched through the valve and through the fitting attached to the main pipeline diametrically through the main pipeline and into the cross-line. Thereafter, the pig moves by fluid flow, either gas or liquid, through the cross-line to perform any of the usual services that can achieved by a pig. For instance, pigs can be employed to make geometry measurements to detect indentations, buckles or other obstructions in the pipeline. Pigs can be employed for cleaning the interior of the cross-line. Pigs can be employed for detecting corrosion in the walls of the cross-line by the use of magnetic flux leakage or sonic inspection technologies. 
   In addition to being able to introduce a pig into a cross-line by the methods and systems of this invention, other activities can be accomplished that do not employ a pig. For instance, by the use of locking pipe plug, the cross-line can be closed adjacent the point where it intersects the main pipeline. With the cross-line closed, pressure tests can be made. Further, by closing off the cross-line at both ends, it can be depressurized and repairs can be made to it without stopping the flow of the fluids through the main pipeline. 
   Cross-lines typically extend between two main pipelines. In this case it is desirable to provide access to both ends of the cross-line which is accomplished by the steps above indicated being employed on both main pipelines. That is, access can be obtained through the main pipelines into both the opposite ends of the cross-line. 
   The invention herein further provides an apparatus for use when inspecting, testing or repairing a cross-line after access has been provided through the main pipelines to which the cross-line attaches. A branch shield pig guide is disclosed that can be installed in a main pipeline to prevent a pig passing through the main pipeline from being inadvertently diverted into the cross-line. A flow-through pig guide is also disclosed to ensure the passage of a pig diametrically through a main pipeline and into a cross-line. Such flow-through pig guide is always removed after the pigging operation is complete through the cross-line. After access is provided to the cross-line using the concepts of the present invention, locking pipe plugs or cross-line pluggers, both of which are disclosed herein, can be employed for closing off the ends of the cross-line for reasons above described. 
   A better understanding of the invention will be obtained from the following detailed description of the preferred embodiments and claims, taken in conjunction with the attached drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a diagrammatic, isometric view showing an excavation in the earth in an area having two main pipelines and a cross-line. This figure shows the method of this invention for providing access to the cross-line by cutting a hole in the side wall of each of the main pipelines, each hole being diametrically opposite the attachment of the cross-line. 
       FIG. 2  is an isometric view showing a main pipeline in dotted outline and showing, in solid line, a flow-through pig guide that is temporarily inserted through a main pipeline when a pig is being launched into the cross-line. 
       FIG. 3  is an isometric view of a branch shield pig guide that can be inserted into a main pipeline after access has been provided to a cross-line to restore pigability of the main pipeline. That is, the branch shield pig guide is used to ensure that a pig passing through a main pipeline is not inadvertently diverted into a cross-line. 
       FIG. 4  is an exploded view of a locking pipe plug that can be used for closing the interior of a cross-line and showing a tool that is used for the installation of the locking pipe plug. 
       FIG. 5  is a cross-sectional view of a locking pipe plug of the type shown in  FIG. 4 . In this view the locking pipe plug is in the non-expanded condition as when it is being inserted into or removed from the interior of the cross-line. 
       FIG. 6  shows the locking pipe plug of  FIGS. 4 and 5  after having been actuated to a secure position within the interior of the cross-line in a manner to provide leak proof closure of the cross-line. 
       FIG. 7  is a side view of the cross-line plugger that can be used to close off the opening in a main pipeline where communication is provided with a cross-line. 
       FIG. 8  is a side view of the cross-line plugger rotated 90° with respect to  FIG. 7 . 
       FIG. 9  is an isometric view of a cross-line plugger of  FIGS. 7 and 8 . 
       FIG. 10  is an elevational front view of the cross-line plugger of  FIGS. 7 ,  8  and  9 . 
       FIG. 11  is an elevational rear view of the cross-line plugger of  FIGS. 7 ,  8 ,  9  and  10 . 
       FIG. 12  is an isometric view of a typical instrument pipeline pig, shown in small scale, that can be launched into the cross-line after the methods of this invention are employed to provide access diametrically through main pipelines to which the cross-line connects. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   It is to be understood that the invention that is now to be described is not limited in its application to the details of the construction and arrangement of the 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 purposes of description and not limitation. 
   Elements illustrated in the drawings are identified by the following numbers: 
   
     
       
             
             
           
         
             
                 
             
           
           
             
               10 
               Earth&#39;s surface 
             
             
               12 
               Excavation 
             
             
               14 
               First main pipeline 
             
             
               16 
               Second main pipeline 
             
             
               18 
               Cross-line 
             
             
               20 
               Connection of the cross-line 
             
             
               22 
               Branch fitting 
             
             
               24 
               Flange fitting 
             
             
               26 
               Valve 
             
             
               28 
               Pig launcher 
             
             
               30 
               Pipeline pig 
             
             
               32 
               Hydraulic ram 
             
             
               34 
               Plugging machine 
             
             
               36 
               Pig signal device 
             
             
               38 
               Branch fitting 
             
             
               40 
               Flange fitting 
             
             
               42 
               Valve 
             
             
               44 
               Pig catcher 
             
             
               46 
               Hot tap machine 
             
             
               48 
               Flow-through pig guide 
             
             
               50 
               Tubular body 
             
             
               52 
               Slotted openings 
             
             
               54 
               Outer diameter 
             
             
               56 
               Locking ring flange 
             
             
               58 
               External groove 
             
             
               60 
               Branch shield pig guide 
             
             
               62 
               Tubular body portion 
             
             
               64 
               Lateral tubular portion 
             
             
               66 
               Locking ring flange 
             
             
               68 
               Circumferential groove 
             
             
               70 
               Short length tubular portion 
             
             
               72 
               Bars 
             
             
               74 
               Bars 
             
             
               76 
               Locking pipe plug 
             
             
               78 
               Tightening nut 
             
             
               80 
               Ram expander 
             
             
               82 
               Shaft 
             
             
               84 
               Base member 
             
             
               86 
               Tubular portion 
             
             
               88 
               Radial flange 
             
             
               90 
               Compression member 
             
             
               92 
               Seal member 
             
             
               94 
               Actuation member 
             
             
               96 
               Cup portion 
             
             
               98 
               Frusto-conical surface 
             
             
               100 
               Segmented slips 
             
             
               102 
               Base portion 
             
             
               104 
               Bolt 
             
             
               106 
               Bolt head 
             
             
               108 
               Cross-line plugger 
             
             
               110 
               Back up plate 
             
             
               112 
               Elastomer seal 
             
             
               114 
               Attachment guide 
             
             
               116 
               Pipeline pig 
             
             
               118 
               Bypass line 
             
             
               120 
               Bypass valve 
             
             
                 
             
           
        
       
     
   
   Referring first to  FIG. 1 , an environment in which the principles of this invention can be practiced is illustrated. This figure shows the earth&#39;s surface  10  having an excavation  12  that reveals a first main pipeline  14 , a second main pipeline  16  and a cross-line  18 . This invention provides improved methods, systems and apparatuses for verifying the integrity of cross-line  18 . 
   The first step in practicing the invention to provide access to cross-line  18  is to affix a branch fitting  22  to the exterior of primary pipeline  14  on the side thereof diametrically opposite the point of intersection  20  of cross-line  18 . The term “cross-line” could equally as well be “branch pipeline” as either term is indicative of a line that extends perpendicularly from a primary pipeline. The branch fitting  22  needs to be of a diameter at least equal to the diameter of cross-line  18  but preferably is of a diameter equal to that of the main pipeline  14 . Such branch fitting will typically include a flange  24  which receives the attachment of a full opening valve  26 . After valve  26  has been attached, then a hot tap machine (not shown) is secured to the valve. The use of hot tapping machines to provide access to the interior of a pipeline is well known in the industry. For specific teachings of the construction, operation and methods of use of hot tapping machines, reference may be had to the following United States patents: 
   U.S. Pat. No. 4,579,484 entitled “Underwater Tapping Machine”; and 
   U.S. Pat. No. 5,439,331 entitled “High Pressure Tapping Apparatus”, that have been previously identified. 
   By use of a hot tapping machine a shell cutter (not shown) is extended through valve  26 , flange  24  and branch fitting  22  to engage the exterior sidewall of main pipeline  14  so that an opening is cut in the side wall of main pipeline  14 . The opening is diametrically opposite the connection  20  of cross-line  18  to the main pipeline  14 . 
   After such large diameter opening is cut in the side wall of main pipeline  14 , the piece cut out of the pipeline is removed through valve  26 . Valve  26  can then be closed and the hot tapping machine (not shown) can be removed and in place of the hot tapping machine, a pig launcher  28  is attached to valve  26 . Pig launchers are well known in the pipeline industry. Essentially a pig launcher is a device that permits, at atmospheric pressures, a pipeline pig such as the pipeline pig  30  illustrated in  FIG. 1 , to be positioned within the launcher. The pig launcher is then hermetically sealed. Valve  26  can then be opened and by means such as a hydraulic ram  32 , pipeline pig  30  can be pushed out of pig launcher  28 , through valve  26  and branch fitting  22 , and diametrically through main pipeline  14  into the interior of cross-line  18 . By force of fluid flow, either liquids or gases, the pig can then be caused to move through cross-line  18 . In  FIG. 1 , a pipeline pig  30  is indicated by dotted outline as moving through cross-line  18 . 
   In order to ensure the passage of a pig  30  through cross-line  18 , increased fluid flow pressure can be obtained by temporarily closing or at least partially closing main pipeline  14 . For this purpose, a plugging machine generally indicated by the numeral  34  can be affixed to pipeline  14  downstream of the cross-line connection. A plugging machine which functions as previously described can provide an opening into the interior of main pipeline  14  through which a flow blockage apparatus (not shown) can be inserted for temporarily blocking or at least reducing fluid flow through the main pipeline. Such flow blockage mechanism is well known in the pipeline industry and is commercially available from T.D. Williamson, Inc. of Tulsa, Okla., U.S.A. 
   With fluid flow blocked or at least restricted by way of a plugging machine  34  and the insertion of a flow blockage mechanism, the pipeline pig  30  will be forced through the interior of cross-line  18 . The pig  30  may be of any type that is currently used in the industry including geometrical measurement pigs, cleaning pigs, corrosion measurement pigs and so forth. Movement through cross-line  18  of the pig can be verified by the use of pig signaling devices  36  that are attached to the exterior of cross-line  18 . Two such pig signaling devices are shown in  FIG. 1 . 
   In  FIG. 1  a second branch fitting  38  is shown as having been attached to second main pipeline  16  opposite the connection of cross-line  18 . As with first pipeline  14 , after the branch fitting  18  is attached with a flange  40 , a valve  42  is employed. By accessing the exterior surface of main pipeline  18  through valve  42 , a hot tapping machine (not shown) may be employed to provide an opening in the wall of second main pipeline  16 . After such opening is provided, the hot tapping machine is removed and a pig catcher  44  can be installed. In this way, after the pipeline pig  30  has traversed through cross-line  18  to perform any of the functions that are commonly available by the use of a pipeline pig, the pig is captured within catcher  44  and may be removed. 
   As has been described, to augment fluid flow pressure through cross-line  18  to cause pig  30  to move therethrough, it may be desirable to block the fluid flow that normally occurs within second main pipeline  16  and for this reason, a hot tap machine can be employed so as to provide an opening into the interior of second main pipeline  16  and the insertion of flow blockage equipment with a plugging machine to temporarily block or restrict fluid flow. Thus with flow blocked or restricted downstream of the cross-line in first main pipeline  14  and blocked or restricted upstream of the cross-line in second main pipeline  16 , fluid flow pressure through cross-line  18  is optimized to ensure movement of pipeline pig  30  through it and into position for retrieval. 
   After the opening through the side wall of first pipeline  14  has been accomplished as described, it is important that provisions be made so that when pipeline pig  30  is injected diametrically through the main pipeline that the pig will pass into cross-line  18  and not become lodged within the main pipeline. For this reason, a flow-through pig guide as generally indicated by the numeral  48  is employed. The flow-through pig guide is illustrated in  FIG. 2 . Flow-through pig guide  48  is inserted diametrically through first main pipeline  14  that is illustrated in dotted outline in  FIG. 2 , the flow-through pig guide  48  passing through valve  26 . Flow-through pig guide  48  has a tubular body  50  with slotted openings  52  therein. The outer end portion  54  is of external diameter so that it can extend telescopically within the interior of cross-line  18 . 
   The inner end of flow-through pig guide  48  has a locking ring flange  56  with an external circumferential groove  58  therein. Flange fittings  24  and  40 , as previously identified, are preferably of the type that facilitate receiving an internal device and removably locking it in place. Such a device is illustrated and described in detail in U.S. Pat. No. 3,766,947 entitled “Fluid-Type Closure”, issued Oct. 23, 1973. This patent teaches a type of flange that has provisions for actuation of a plurality of locking elements that can be moved radially inwardly or radially outwardly by adjustment of screw mechanisms on the exterior of the flange (not shown in  FIG. 1 ). These locking elements are moved into external circumferential groove  58  to thereby hold flow-through pig guide  48  in position as it extends diametrically through pipeline  14 . 
   The use of the flow-through pig guide ensures, as above indicated, the passage of a pig  30  through the main pipeline  14  so that the pig passes into cross-line  18 . In the same manner, a flow-through pig guide as illustrated in  FIG. 2  is positioned diametrically within second pipeline  16  in which case the flange  40  (as seen in  FIG. 1 ) is of the type that has locking elements that can be extended into and withdrawn from the circumferential groove  58 . 
   The flow-through pig guide  48  of  FIG. 2  is used only when a pig is being launched into or received diametrically through main pipeline  14  or  16  and thereafter removed since if left in position they would interfere with the passage of pigs through the main pipelines. 
   After the method of this invention has been employed as has been described to provide access diametrically through main pipelines  14  and  16  and after pigging operations or other work required to be done on cross-line  18  has been completed, it is important that the main pipelines  14  and  16  be restored to function in the manner as if such work on the cross-line had not been done. That is, it is important that the provision of the openings through the walls of main pipelines  14  and  16  do not interfere with the passage of pipeline pigs through them. For this purpose, after the work on the cross-line  18  has been completed, a branch shield pig guide generally indicated by the numeral  60  as shown in  FIG. 3 , can then be installed within the main pipelines  14  and  16 . The branch shield pig guide includes a main short length tubular body portion  62  that is of external dimensions slightly less than the internal diameter of main pipeline  14 . Extending from tubular body portion  62  is a lateral tubular portion  64  that connects the main body portion to a locking ring flange  66  that has a circumferential groove  68 . Thus, by use of a locking ring system as illustrated and described in U.S. Pat. No. 3,766,947 as previously mentioned, the branch shield pig guide  60  can be maintained within the interior of main pipeline  14 . 
   Extending from the tubular body portion  62  is a short length tubular portion  70  of external diameter substantially equal to the interior diameter of cross-line  18 . When positioned within the interior of main pipeline  14 , the short length tubular portion  70  extends telescopically within the cross-line to assist in anchoring the branch shield pig guide  60  in position. To prevent the possibility of a pig passing through main pipeline  14  attempting to enter cross-line  18 , paralleled bars  72  close tubular portion  70 . Similar bars  74  are shown closing the lateral tubular portion  64  for similar reasons, that is, to close off the possibility of a pig attempting to enter this passageway. The use of bars  74  is optional since there is no fluid flow through this lateral tubular passageway that would tend to cause a pig to enter it whereas fluid flow through the short length tubular portion  70  is possible. 
   The branch shield pig guide  60  is installed through valve  26  as previously described by means of a hot tapping machine so that such device can be installed while the main pipeline  14  is under pressure. Branch shield pig guide  60  includes a flange closure system  66  to close off flange  24  enabling valve  26  to be removed and a blind flange (not shown) installed. 
   A branch shield pig guide  60  will also be installed in second main pipeline  16  for the same reasons as described with reference to the first main pipeline  14 . 
   After access to cross-line  18  is provided diametrically through main pipelines  14  and  16 , it is then possible to seal off both ends of the cross-line  18  to allow for pressure testing, as is sometimes required to ensure the integrity of the cross-line. For this purpose, a locking pipe plug  76  as generally indicated in  FIG. 4  and in greater detail in  FIGS. 5 and 6  is employed. As shown in  FIG. 4  the locking pipe plug  76  has, on the rearward end thereof, a tightening nut  78  that can be grasped by a ram expander  80  that is positioned and rotated by a shaft  82 . By means of hot tapping equipment that controls the axial and rotational position of ram expander  80 , it can be extended diametrically through the interiors of both main pipeline  14  and  16 . In this way a locking pipe plug  76  can be inserted in each end of cross-line  18 . 
   The details of the locking pipe plug are shown in  FIG. 5 . A base member  84  has a tubular portion  86  that is externally threaded and receives nut  78  thereon. The base portion  84  has an integral radial flange portion  88  that faces a radial compression member  90  that is slidable on tubular portion  86 . Between radial flange portion  88  and compression member  90  is a circumferential elastomeric seal member  92 . In the relaxed position as shown in  FIG. 5  the seal member is cupped outwardly as indicated in the cross-sectional view. Received on tubular portion  86  is an actuation member  94  having a cupped portion  96 . The compression member  90  has a frusto-conical surface  98  that receives segmented slips  100 . 
   When nut  78  is threadably tightened by rotation of shaft  82  and thereby ram expander  80  as seen in  FIG. 4 , the threaded advancement of nut  78  towards base member  84  moves compression member  90  towards base member radial flange  88 , compressing seal member  92 . The segmented slips  100  are concurrently moved forward and the reaction of the slips with frusto-conical surface  98  causes the slips to expand radially outwardly for engagement with the interior of cross-line  18 . In this way the locking pipe plug  76  is tightly engaged within the interior of cross-line  18 . With a locking pipe plug at each end of the cross-line, pressure can be applied to it to test for leakage. High pressure can be applied to test the bursting strength of cross-line  18 . 
   After such tests are completed, each locking pipe plug can be removed by reversing the rotation of nut  78 , and retrieving the plug with expander  80  as affixed to shaft  82 . 
   Another way of closing off the opposed ends of cross-line  18  is by the use of a cross-line plugger  108  as shown in  FIGS. 7 through 11 . This item has a base portion  102  with a bolt  104  having a head  106  that forms the forward end of the cross-line plugger, which is generally indicated by the numeral  108 . Bolt  104  receives an arcuate back up plate  110  having an elastomer seal  112  on the forward surface thereof. The radius of curvature of the back up plate  110  and the forward surface of elastomer seal  112  is the same radius of curvature as the interior circumferential surface of the main pipelines  14  and  16 . The rearward end of the cross-line plugger  108  is an attachment guide  114 . 
   The cross-line plugger  108  is used in this way: with an opening having been formed in each of the main pipelines  14  and  16 , each ends of cross-line  18  can be temporarily closed by inserting through each open valves  26  and  42 , a cross-line plugger  108  attached to a rod (not shown) extending from hydraulic cylinder  32 . Cross-line plugger  108  passes diametrically through a main pipeline. The elastomer seal  112  of each plugger engages the circumferential area of the internal cylindrical wall of a main pipeline that surrounds the opening communicating with cross-line  18 . In this way the cross-line is plugged off at each end. It should be kept in mind that the cross-line plugger  108  is not intended for use to resist high pressure within cross-line  18  but cross-line pluggers  108  may be used to isolate the cross-line from the main pipelines and permit drainage of liquids and gases from it so as to permit repairs. The cross-line pluggers are not intended for permanently closing the cross-line. 
     FIG. 12  is a small scale isometric representation of a pipeline pig  116  which may be of the type used for determining the structural integrity of cross-line  18 . Pigs  116  of the type shown in  FIG. 12  may include highly technical systems such as for measurement of corrosion by magnetic flux leakage, or sonic energy reflections. 
     FIG. 1  illustrates an additional element that is not directly related to the methods and systems of this invention but that make the inventions herein more useful. Extending from cross-line  18  is a bypass line  118  that connects to second main pipeline  16  downstream of branch fitting  38 . A bypass valve  120  controls flow through bypass line  118 . When a pig  30  is launched through branch fitting  22  and diametrically through first main pipeline  14 , valve  120  is opened. When pipeline pig  30  gets to near the end of cross-line  18  as shown in dotted outline in  FIG. 1 , the restriction to fluid flow imposed by the pipeline pig will cause fluid flow through bypass line  118 , stopping further movement of the pipeline pig which is then in position for retrieval by apparatus extending from pig catcher  44 . When a pig is not being received bypass valve  120  will normally be closed. 
   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 claim or claims, including the full range of equivalency to which each element thereof is entitled.