Abstract:
A method of providing access to the interior of a cross-line that intersects with a primary pipeline of equal or greater diameter includes the steps of attaching a branch fitting to the exterior of the primary pipeline, affixing a full opening valve to the branch fitting, securing a hot tap machine to the valve, using the hot tap machine to cut an opening in the primary pipeline of a diameter at least equal to the internal diameter of the cross-line, and removing the machine leaving an access diametrically through the valve and primary pipeline into the interior of the cross-line for installing pipeline inspection or cleaning pigs and/or a locking plug. A rotation resistor facilitates securing a locking plug within the pipeline.

Description:
REFERENCE TO PENDING APPLICATIONS  
       [0001]     This is a continuation-in-part of U.S. patent application Ser. No. 11/133,514, filed May 20, 2005 and entitled Cross-Line Plugging System. The application is not related to any federally sponsored research or development. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     I. Field of the Invention  
         [0003]     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.  
         [0004]     II. Description of the Prior Art.  
         [0005]     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 modem 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.  
         [0006]     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.  
         [0007]     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.  
         [0008]     For additional background information relating to this invention, reference may be had to the following previously issued United States patents.  
                                       Patent               Number   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  
       [0009]     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.  
         [0010]     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.  
         [0011]     1. U.S. Pat. No. 4,579,484 entitled “Underwater Tapping Machine”, Sullivan, issued Apr. 1, 1986;  
         [0012]     2. U.S. Pat. No. 5,439,331 entitled “High Pressure Tapping Apparatus, Andrew et al, issued Aug. 8, 1995”  
         [0013]     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.  
         [0014]     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.  
         [0015]     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.  
         [0016]     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.  
         [0017]     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.  
         [0018]     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  
       [0019]     Preferred embodiments of the invention will now be described in further detail. Other features, aspects, and advantages of the present invention will become better understood with regard to the following detailed description, appended claims, and accompanying drawings (which are not to scale) where:  
         [0020]      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.  
         [0021]      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.  
         [0022]      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.  
         [0023]      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.  
         [0024]      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.  
         [0025]      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.  
         [0026]      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.  
         [0027]      FIG. 8  is a side view of the cross-line plugger rotated 90° with respect to  FIG. 7 .  
         [0028]      FIG. 9  is an isometric view of a cross-line plugger of  FIGS. 7 and 8 .  
         [0029]      FIG. 10  is an elevational front view of the cross-line plugger of  FIGS. 7, 8  and  9 .  
         [0030]      FIG. 11  is an elevational rear view of the cross-line plugger of  FIGS. 7, 8 ,  9  and  10 .  
         [0031]      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.  
         [0032]      FIG. 13  is an elevational view, shown partially in cross-section, of an improved locking pipe plug of the type shown in  FIGS. 5 and 6 . The improved locking pipe plug includes, among other advantages, a rotation resistor.  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0033]     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.  
         [0034]     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            76A   Improved 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           126   Retainer spring           128   External threads           132   Rotation resistor           134   Wire brush           136   Wires           138   Outer end           140   Pipe inner surface           142A, B   Face plates           144   Opening           146   Bolt           148   Threaded opening           150   Holder           152   Inner end portion           154   Threaded opening           156   Interior recess           158   Pipe plug           160   Washer           162   Internal threads           164   Flange           166   Openings                      
 
         [0035]     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 .  
         [0036]     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:  
         [0037]     U.S. Pat. No. 4,579,484 entitled “Underwater Tapping Machine”; and  
         [0038]     U.S. Pat. No. 5,439,331 entitled “High Pressure Tapping Apparatus”, that have been previously identified.  
         [0039]     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 .  
         [0040]     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 .  
         [0041]     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, Oklahoma, U.S.A.  
         [0042]     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 .  
         [0043]     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.  
         [0044]     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.  
         [0045]     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 .  
         [0046]     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 .  
         [0047]     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 .  
         [0048]     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.  
         [0049]     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 .  
         [0050]     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.  
         [0051]     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.  
         [0052]     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 .  
         [0053]     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 .  
         [0054]     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 .  
         [0055]     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 .  
         [0056]     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 .  
         [0057]     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 111 . 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 .  
         [0058]     The cross-line plugger  108  is used in this way: with an opening having been formed in  110  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.  
         [0059]      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.  
         [0060]      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.  
         [0061]      FIG. 13  illustrates in elevational view, shown partially in cross-section, an improved locking pipe plug generally indicated by the numeral  76 A. The improved locking pipe plug employs the basic concepts of the locking pipe plug illustrated and described with reference to  FIGS. 5 and 6  and the components in the improved locking pipe plug  76 A that have the similar structure and function to the components in  FIGS. 5 and 6  are provided with the same numbers.  
         [0062]     Thus, the embodiment of  FIG. 13 , as compared with the embodiment of  FIGS. 5 and 6 , has these similar functioning components: a base member  84  with a tubular portion  86  and a radial flange  88 ; an expansion member  90 ; an elastomeric seal member  92 ; an actuation member  94  having a cup portion  96 ; and a frusto-conical surface  98  on compression member  90  that receives segmented slips  100 . In addition to the similarities in the locking pipe plug illustrated in  FIGS. 5 and 6  and that of  FIG. 13 ,  FIG. 13  shows additional features and improvements.  
         [0063]     As has been previously described, segmented slips  100  are formed of metal to securely lock into the interior wall of the pipe in which the improved locking pipe plug  76 A is positioned. A retainer spring  126  encircles the segments making up segmented slips  100  to hold them in contact with frusto-conical surface  98  of compression member  100 .  
         [0064]     Actuation member  94  is received slideably on the external threads  128  of tubular portion  86  of base member  84 . When the improved pipe plug  76 A is inserted into a pipe, rotation of holder  150 , with its internal threads  154  engaged in the external threads  128  on tubular portion  86 , causes actuation member  94  to be axially advanced so that it moves the cup portion  96  against segment slips  100  to thereby force compression member  90  in the direction towards radial flange  88 . This causes radially expansion of segmented slips  100  and simultaneously axially advances compression member  90  towards flange  88 , thereby compressing seal member  92 . Thus, threadably rotating holder  150  simultaneously causes segmented slips  100  to lock against the interior surface of the pipe in which the plug is positioned and to radially expand the seal member  92  to seal against the wall of the pipe in which the plug is positioned.  
         [0065]     When holder  150  is rotated to set the locking pipe plug it is necessary that the pipe plug itself not rotate, that is, there must take place threading action between the internal threads of holder  150  and external threads  128  on the base member tubular portion  86 . Stating it another way, it is important that the base member  84  be restrained from rotation so that actuation member  94  can be slideably advanced, through rotation of holder  150 , to actuate segmented slips  100  and seal member  92 . The embodiment of the improved locking plug  76 A of  FIG. 13  includes an innovative system of restraining rotation of the base member  84  so as to permit locking a plug in position.  
         [0066]     When the improved locking pipe plug  76 A is inserted into a pipeline, it is necessary to rotate holder  150  relative to base member  84  to threadably advance it and thus slideably advance the actuation member  94  so that the cup portion  96  presses against slips  100  to start the process of locking the pipe plug within the pipe. Thus it is helpful if a system is provided for resisting the rotation of base member  84  especially during the initial process of tightening holder  150  on the actuation member tubular portion  86 . For this purpose, the improved locking pipe plug  76 A includes a rotation resistor generally indicated by the numeral  132 . In  FIG. 13 , a preferred embodiment of a rotation resistor  132  is illustrated and is in the form of a stiff cleaning brush assembly commonly used on pipeline cleaning pigs. An alternative embodiment is essentially of a cylindrical wire brush that is of the type readily commercially available and that is typically used as a part of a rotating mechanism for cleaning the surface of metallic objects. Thus in the illustrated embodiment, the rotation resistor  132  is a wire brush  134  that provides a large number of radially extending flexible wires  136 . Each of the wires  136  has an outer free end  138  arranged so that the length of the wires  136  extends the outer ends thereof  138  beyond the normal diameter of the pipe in which the plug is to be used. That is, the wires  136  are of sufficient lengths so that the outer ends  138  thereof flexibly engage the pipe inner surface  140 .  
         [0067]     Wire brush  134  typically includes opposed face plates  142 A and  142 B that retain the wires  136  therebetween. Face plates  142 A and  142 B each have a central opening  144  therein that receives a bolt  146 . Bolt  146  is received in a threaded opening  148  in base member  84 . Thus the rotation resistor  132  is rotatably locked to base member  84 .  
         [0068]     When the improved locking pipe plug  76 A is inserted into a pipe to plug the interior of the pipe against fluid flow therethrough, the wires  136  of the wire brush flex or bend so that the pipe plug is relatively easily inserted into the pipe. The wire ends  138  engage the internal surface  140  of the pipe and resist the rotation of the base member  84 . It is to be emphasized that the wire brush  134  does not lock the plug base member  84  against rotation but merely resists rotation. All that is required is that rotational resistance be applied to the base member  84  as the holder  150  is rotated to threadably advance actuation member  94  slideably on tubular portion  86 . As the actuation member  94  advances, segmented slips  100  engage the pipe interior surface and immediately serve to resist rotation of the pipe plug. As the advance of the base member  84  continues compressive force is applied against seal member  92  so the outer circumferential surface thereof expands to engage the interior of the pipe to further resist rotation. Thus it can be seen that after actuation member  94  is advanced, the segmented slip  100  and seal member  92  themselves begin to lock the pipe plug against rotation. After this action takes place the rotational resistance applied by rotation resistor  132  is no longer required. Therefore, the function of wire brush  134  is to merely resist rotation to get the process of anchoring the pipe plug in the pipe started. In the same manner, when it is necessary to remove the pipe plug, as the holder  150  is threadably retracted, the contact of segmented slips  100  and seal member  92  with the pipe interior surface gradually decreases and the rotational resistor  132  takes over to allow the actuation member  94  to be retracted to the point that the plug can be axially extracted from the pipe.  
         [0069]     Another element illustrated in  FIG. 13  that is not shown in  FIGS. 5 and 6  is a holder generally indicated by the numeral  150 . Holder  150  is tubular with an inner end portion  152  having an internally threaded opening  154  therein. The forward portion of holder  150  is tubular providing an interior recess  156  that receives a threaded pipe plug  158 . Internally pipe threads  162  at the outer end of the base member tubular portion  86  threadably and sealably receives pipe plug  158 . A washer  160  has an outer diameter greater than the diameter of holder threaded opening  154 . Thus after holder  150  is threaded onto the outer end of tubular portion  86 , pipe plug  158  and washer  160  may be secured in position to prevent holder  150  from being inadvertently unthreaded from base member tubular portion  86 .  
         [0070]     The outer end of holder  150  has a radial flange  164  with openings  166  therein. Bolts extending through openings  166  (not shown) can be used to hold locking pipe plug  76 A, for inserting it into a pipe and correspondingly for removing it after a plug has been inserted, onto shaft  82  of an insertion tool or onto a tapping machine  46  of the type as commonly employed in piping technology and that is readily commercially available from T.D. Williamson, Inc. of Tulsa, Okla.  
         [0071]     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.