REFERENCE TO PENDING APPLICATIONS 
     This application is not based upon any pending domestic or international patent applications. 
     FIELD OF THE INVENTION 
     The invention relates to apparatus systems and methods for plugging a pipeline having liquids or gases flowing therethrough utilizing seals on the exterior of the pipeline. 
     BACKGROUND OF THE INVENTION 
     This invention relates to systems and methods for plugging a pipeline under pressure. “Pipeline” as used hereinafter is inclusive of any tubular member made of metal for carrying fluid (liquids or gases). Whereas U.S. Pat. No. 7,270,139 is particularly useful for controlling flow of high temperature liquids or gases, the present invention can be used for either ambient or high temperature applications. The composition of the elastomeric seals determines the range of the applicable temperature. However, the ferrule design may be used at elevated as well as ambient temperatures. 
     Tools or machines for tapping or for closing fluid flow therethrough include the following: 
     
       
         
               
               
               
             
           
               
                   
               
               
                 PAT. NO. 
                 INVENTOR 
                 TITLE 
               
               
                   
               
             
             
               
                 3,614,252 
                 Rose et al. 
                 Tapping Apparatus 
               
               
                 4,579,484 
                 Sullivan 
                 Under Water Tapping Machine 
               
               
                 4,880,028 
                 Osburn et al. 
                 Completion Machines 
               
               
                 5,439,331 
                 Andrew et al. 
                 High Pressure Tapping Apparatus 
               
               
                 5,612,499 
                 Andrew et al. 
                 Method of Inserting A Sensor Into A 
               
               
                   
                   
                 Pipeline 
               
               
                 6,012,878 
                 Hicks 
                 Pressure Balanced Subsea Tapping Machine 
               
               
                 7,270,139 
                 Calkins et al. 
                 Cam-Assisted, Wedge Actuated, Metal-to- 
               
               
                   
                   
                 Metal Seal, Block and Bleed Plugging Tool 
               
               
                   
               
             
          
         
       
     
     Tapping machines, such as the kind described in the above-mentioned U.S. patents, are for tapping a hole in a pipeline while liquids or gases are flowing through them, that is, while the pipeline is under pressure. Tapping procedures of this type are customarily carried out primarily for one of two purposes, that is, to provide a branch fitting on the pipeline or to enable fluid flow through the pipeline to be blocked. Other examples of prior art that describe and illustrate plugging the interior of a pipe include the following U.S. Pat. Nos.: 
     
       
         
               
               
               
             
           
               
                   
               
               
                 PAT. NO. 
                 INVENTOR 
                 TITLE 
               
               
                   
               
             
             
               
                 3,170,226 
                 Allan 
                 Line Stopping and Valve Inserting 
               
               
                   
                   
                 Apparatus and Method 
               
               
                 3,599,663 
                 Ver Nooy 
                 Hot Tapping Apparatus 
               
               
                 3,626,475 
                 Hicks 
                 High Temperature Pipe-Plugging 
               
               
                   
                   
                 Apparatus 
               
               
                 3,665,966 
                 Ver Nooy 
                 Pipe Plugger 
               
               
                 3,785,041 
                 Smith 
                 Method For Plugging Pipe 
               
               
                 3,872,880 
                 Ver Nooy et al. 
                 Plugging Apparatus 
               
               
                 4,411,459 
                 Ver Nooy 
                 Branch Fitting for Providing Access to 
               
               
                   
                   
                 the Interior of a Pipe 
               
               
                 5,443,095 
                 Glossop, Jr. 
                 Fluid Blocking Device 
               
               
                 5,531,250 
                 Freeman et al. 
                 Device for Plugging the Interior of a 
               
               
                   
                   
                 Pipe 
               
               
                 7,270,139 
                 Calkins et al. 
                 Cam-Assisted, Wedge Actuated, 
               
               
                   
                   
                 Metal-to-Metal Seal, Block and Bleed 
               
               
                   
                   
                 Plugging Tool 
               
               
                 GB1,064,398 
                 Pass and Co. 
                 Pipe Line Plugger 
               
               
                   
                 Ltd. 
               
               
                   
               
             
          
         
       
     
     BRIEF SUMMARY OF THE INVENTION 
     The invention herein makes use of the known technology of welding onto a pipe having fluid flow therethrough a pair of collars. Each of the collars is a toroid that is severed to provide a set of two toroidal halves that are fitted together around the pipe. Each collar set consisting of two spaced apart parallel collars are secured to the exterior of the pipe. Each collar has a machined face which can be achieved by machining before the collars have been welded to the pipe. Thus a set of collars affixed to the exterior surface of a pipe provide forward planar faces that face each other. The collar faces are parallel to each other and spaced apart an accurately establish distance. After each collar is affixed to the pipe, the collar halves are then welded to each other. Further, the two halves of each collar are welded where the back face meets the pipe around the 360° circumference of the pipe. After the collars are installed, they provide uninterrupted circumferential planar sealing surfaces that face each other. The sealing surfaces are parallel to each other and in radial planes perpendicular to longitudinal axis of the pipe. 
     The sealing face of each collar includes a circumferential recess, or circumferential slot, adjacent the interior circumferential surface of the pipe to which they are affixed. 
     After the collars are welded to the exterior surface of a pipe, containment fittings are welded to the collars to provide a housing of internal dimensions greater than the external surface of the pipe. The shape of the containment fittings can vary. One type of containment housing, as illustrated herein, is in the form of a sphere with an open top, or the housing can be non-spherical by having a bottom usually in the form of a cup shaped member with a flange fitting at the upper end. 
     After the containment housing, which may include a bottom member and an upper flange, has been welded to the collars, the containment housing is typically pressure tested to ensure there are no leaks and that the collars and the containment housing have the structural integrity to contain the maximum pressure to which they will be subjected. 
     Even though the preferred embodiment for installing the collars is described above, it is recognized that the collars may be pre-welded to the containment fittings prior to being welded to the pipe. 
     After the collars and the containment housing components have been installed and tested, a valve is secured to the containment housing flange. A tapping machine system, well known in the industry, is secured to the upper surface of the valve and then pressure is applied to test for leaks. Thereafter, by use of the tapping machine, a complete section of the pipeline is removed from between the collars. The concept of removing a complete section rather than tapping only a hole in the pipe is illustrated in U.S. Pat. No. 5,612,499 entitled “Method of Inserting A Sensor Into A Pipeline”. When a section of the pipeline has been cut, it is removed exposing the opposed ends of the cutout section of the pipeline, the exposed ends being surrounded by the collars that have previously been attached to the pipe. 
     After the collars and the containment housing components have been affixed to the exterior of the pipe, a tapping machine attached and a section of the pipe is cut and removed, the next step is to seal the opposed ends of the pipe employing a plugging tool. The plugging tool is inserted as an assembly into the interior of the containment housing. The plugging tool carries with it opposed sealing cups, each having a circumferential sealing surface of internal diameter greater than the external diameter of the pipe. The plugging tool assembly is lowered into the containment housing and actuated such that the opposed sealing cups are advanced in directions towards the open ends of a severed pipe and towards opposed circumferential elastomeric seals supported in the circumferential slot on each collar. 
     In one embodiment the plugging tool assembly includes upper and lower cam followers affixed to each of the seal cups rearwardly of the forward faces thereof. Top and bottom supports each having a pair of cam slots for receiving the cam followers and are configured to urge the seal cups towards the toroidal elastomeric seals carried by each of the collars. The plugging tool assembly includes translation apparatus for moving the top and bottom supports away from each other to thereby urge the seal cups towards the toroidal elastomeric seals. 
     In one embodiment of the invention a pair of wedge members are forced against rearward surfaces of the seal cups to simultaneously force them into sealing contact with the elastomeric seals on the toroidal collars. In this manner a double block and bleed plugging tool is achieved. After both of the seal cups are forced into sealing condition the interior of the containment housing can be tested to verify that both seal cups are in leak-proof contact with the elastomeric seals on the toroidal collars. 
     In another embodiment, the seal cups are forced into contact with the circumferential elastomeric seals by means a hydraulic cylinder having pistons extending from opposed sides, each piston being laterally displaced by hydraulic fluid forced into the hydraulic cylinder. 
     In another embodiment, the seal cups are forced into contact with malleable metallic ferrules which are sealably crimped onto the exterior of the pipe. 
     Further objects and features of the present invention will be apparent to those skilled in the art upon reference to the accompanying drawings and upon reading the following description of the preferred embodiments. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       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: 
         FIG. 1  is an elevational cross-sectional view of portions of the length of a pipeline having affixed to it a set of collars and a containment housing of the spherical type in which a portion of the pipeline between the collars has been removed. Shown partially within the containment housing, in external view, is a cam actuated plugging system which carries with it first and second seal cups. 
         FIG. 2  is a cross-sectional view of a containment housing with collars affixed to the exterior of a pipe and a portion of the pipe having been removed as shown in  FIG. 1 . In this figure the plugging assembly has been inserted into the containment housing and between opposed ends of the pipe. This figure shows the plugging assembly having been inserted into the containment housing and actuated to force sealing cups in opposite directions from each other and into sealing relationship with elastomeric seals carried by the opposed collars. 
         FIG. 3  is a cross-sectional view as shown in  FIG. 2  but different from  FIG. 2  in that in this figure a containment housing that is secured to the opposed collars is of a different, non-spherical form. In this figure the collars are of trapezoidal cross-sectional configuration and in like manner, the circumferential elastomeric seals are trapezoidal to conform in part to the forward surface configuration of the collars. In this figure the seal cups are shown as having been extended to be in sealing contact with elastomeric seals surrounding the exterior surfaces of the pipeline. 
         FIG. 4  is an elevational cross-sectional view, shown partially cut away, showing a different type of mechanism for expanding the seal cups into sealing engagement with elastomeric seals carried by the collars. In this embodiment the seal cups are pushed laterally away from each other and into contact with externally mounted circumferential elastomeric seals by the use of hydraulic pressure. 
         FIG. 5  is a fragmentary external view of an alternate embodiment of the invention showing an arrangement wherein an elastomeric seal is received on the pipe and in contact with the forward face of a collar and wherein the collar is of square cross-sectional configuration, that is, the collar does not have a circumferential slot for receiving an elastomeric seal. 
         FIG. 6  is an elevational cross-sectional fragmentary view showing the end of a pipe as in  FIG. 5  but wherein the collar has a circumferential slot therein that receives an elastomeric seal. In  FIG. 6 , the elastomeric seal has a cloth backing on the forward and rearward planar surfaces. 
         FIG. 7  is an additional elevational cross-sectional fragmentary view as in  FIGS. 5 and 6  showing the use of an elastomeric seal that includes integrally therewith anti-extrusion springs. 
         FIG. 8  is an additional elevational cross-sectional partial view showing an elastomeric seal supported within a circumferential slot in a collar secured to the exterior of a pipeline and wherein the elastomeric seal has a cloth reinforcing against the rearward face thereof and wherein the forward face includes an anti-extrusion spring. 
         FIG. 9  is an isometric view of an alternate embodiment of the invention wherein a metallic ferrule is secured to the forward end of seal cup showing means by which the ferrule can be held in position for positioning on the end of a pipeline and the process of sealably closing flow through the pipeline. 
         FIG. 10  is a cross-sectional elevational view as previously shown in  FIG. 2  but showing the arrangement of the invention wherein instead of an elastomeric seal as in  FIG. 2 , a metallic ferrule is positioned on each end of the exposed pipeline after the pipeline has been cut and wherein the metallic seals can be deformed by the application of force to sealably close against the forward face of the collars. 
         FIG. 11  is a cross-sectional elevational view illustrating a step in the sequence of positioning metallic ferrules on the end portion  10  of the pipeline. 
         FIG. 12  is an illustration as in  FIG. 11  but showing the first seal cup  56  having been advanced to move the ferrule into contact with the forward face of the first collar in the process of sealing the end of the pipe. 
         FIG. 13  is a further step in the process of mounting the ferrule on the cut end of a pipe in which it is illustrated deformation of the malleable ferrule by pressure applied from first seal cup. 
         FIG. 14  is an illustration of a further step of the process of mounting the metallic ferrule on a pipe and in sealed position relative to the forward face of a first collar and wherein, after the mounting and sealing operations have taken place, the cup is withdrawn leaving the ferrule in sealed position relative to the pipeline and the collar. 
         FIG. 15  is a further step in the illustration of mounting a malleable ferrule on the end of a pipe and in sealed contact with a collar surrounding the pipe and showing the seal cup withdrawn whereby the mechanism used for mounting can be removed from within the containment housing. 
         FIG. 16  shows an alternate embodiment of the process of crimping the ferrule into sealing engagement with the forward end of a collar and in which the collar has a planar forward surface against which the ferrule is pressed.  FIG. 16  also shows an alternate embodiment of the retainer used to hold a ferrule in position as it is mounted on the pipeline in which the retainers are thinner in the direction away from the area wherein the ferrules are retained to thereby provide for increased flexibility of the retainers. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     It is to be understood that this invention is not limited in its application 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 of limitation. 
     Elements shown by the drawings are identified by the following numbers: 
     
       
         
               
               
               
             
           
               
                   
               
             
             
               
                   
                  10 
                 Portion of the pipeline 
               
               
                   
                  12 
                 Portion of the same pipeline 
               
               
                   
                  14 
                 First collar 
               
               
                   
                  16 
                 Second collar 
               
               
                   
                  18 
                 Circumferential weld 
               
               
                   
                  20 
                 Circumferential weld 
               
               
                   
                  22 
                 Forward face 
               
               
                   
                  24 
                 Forward face 
               
               
                   
                  26 
                 Circumferential slot 
               
               
                   
                  28 
                 Circumferential slot 
               
               
                   
                  30 
                 Rearward face 
               
               
                   
                  32 
                 Rearward face 
               
               
                   
                  34 
                 Circumferential elastomeric seal 
               
               
                   
                  36 
                 Circumferential elastomeric seal 
               
               
                   
                  36A 
                 Elastomeric seal 
               
               
                   
                  38 
                 Containment housing, lower portion 
               
               
                   
                  40 
                 Containment housing, upper portion 
               
               
                   
                  42 
                 Welds 
               
               
                   
                  44 
                 Flange 
               
               
                   
                  46 
                 Passageway 
               
               
                   
                  48 
                 Pipe sealing assembly 
               
               
                   
                  50 
                 Top support 
               
               
                   
                  52 
                 Lower support 
               
               
                   
                  54 
                 Vertical shaft 
               
               
                   
                  56 
                 First seal cup 
               
               
                   
                  56A, B 
                 Seal cup 
               
               
                   
                  58 
                 Second seal cup 
               
               
                   
                  60 
                 Upper arms 
               
               
                   
                  62 
                 First roller 
               
               
                   
                  64 
                 Upper arms 
               
               
                   
                  66 
                 Second roller 
               
               
                   
                  68 
                 Downward arms 
               
               
                   
                  70 
                 Downward arms 
               
               
                   
                  72 
                 Roller 
               
               
                   
                  74 
                 Roller 
               
               
                   
                  75 
                 Cam slot 
               
               
                   
                  76 
                 Cam slot 
               
               
                   
                  78 
                 Cam slot 
               
               
                   
                  80 
                 Cam slot 
               
               
                   
                  82 
                 Compression spring 
               
               
                   
                  84 
                 Shaft guide 
               
               
                   
                  86 
                 Top plate 
               
               
                   
                  88 
                 First wedge member 
               
               
                   
                  90 
                 Second wedge member 
               
               
                   
                  92 
                 Stop post 
               
               
                   
                  94 
                 Circumferential recess 
               
               
                   
                  96 
                 Circumferential recess 
               
               
                   
                  98 
                 Outer end of pipe 
               
               
                   
                 100 
                 Outer end of pipe portion 12 
               
               
                   
                 102 
                 Circumferential sealing surface 
               
               
                   
                 104 
                 Circumferential sealing surface 
               
               
                   
                 106 
                 Lower containment portion 
               
               
                   
                 108 
                 Upper containment portion 
               
               
                   
                 109 
                 End cap 
               
               
                   
                 110 
                 Collar 
               
               
                   
                 112 
                 Collar 
               
               
                   
                 114 
                 Frusto-conical surface 
               
               
                   
                 116 
                 Circumferential elastomeric seal 
               
               
                   
                 118 
                 Circumferential elastomeric seal 
               
               
                   
                 120 
                 Tubular housing 
               
               
                   
                 122 
                 Double ended hydraulic cylinder 
               
               
                   
                 124 
                 Positioning element 
               
               
                   
                 126 
                 Recess 
               
               
                   
                 128 
                 Piston 
               
               
                   
                 130 
                 Piston 
               
               
                   
                 132 
                 Hydraulic fluid pressure source 
               
               
                   
                 134 
                 Hydraulic hose 
               
               
                   
                 136 
                 Inlet 
               
               
                   
                 138 
                 Collar 
               
               
                   
                 138A 
                 Collar 
               
               
                   
                 140 
                 Forward face of the seal 
               
               
                   
                 141 
                 Forward face of the collar 
               
               
                   
                 142 
                 Internal circumferential slot 
               
               
                   
                 142A 
                 Internal circumferential slot 
               
               
                   
                 144 
                 Inclined surface 
               
               
                   
                 146 
                 Circumferential elastomeric seal 
               
               
                   
                 146A 
                 Circumferential elastomeric seal 
               
               
                   
                 148 
                 Cloth 
               
               
                   
                 150 
                 Snap ring 
               
               
                   
                 152 
                 Rearward cloth face 
               
               
                   
                 154 
                 Anti-extrusion spring 
               
               
                   
                 156 
                 Interior surface 
               
               
                   
                 158 
                 Forward cloth face 
               
               
                   
                 160 
                 Metallic ferrule 
               
               
                   
                 162 
                 Retainers 
               
               
                   
                 164 
                 Bolt 
               
               
                   
                 166 
                 Recess 
               
               
                   
                 168 
                 Forward face 
               
               
                   
                 170 
                 Radial face 
               
               
                   
               
             
          
         
       
     
     Referring to the drawings and first to  FIG. 1 , a cross-sectional view of the portion of a length of a pipeline is shown after the pipeline has been cut in two and a portion thereof removed in the practice of the invention. A first portion of the length of the pipeline is identified by the numeral  10  and a second portion of the same pipeline shown in cross-section is identified with the numeral  12 . A portion of the pipeline extending from the illustrated portions  10  and  12  has been removed, discarded and is not illustrated. Prior to removal of the missing portion,  FIG. 1  shows that a first circumferential angular collar  14  and a spaced apart, second collar  16  have been affixed to the pipeline. Each of the collars in their assembled form are short length tubular members. While not shown in  FIG. 1  each of collars  14  and  16  is formed of two halves that are assembled on the pipeline. The assembled portions are welded to the pipeline by rearward circumferential welds  18  and  20 . The semi-cylindrical collar portions are then welded longitudinally to each other (not seen in  FIG. 1 ) so that after the welds are completed, collars  14  and  16  are each an integral short length cylindrical member having a forward face. The forward face of collar  14  is identified by the numeral  22  and, in like manner, the forward face of collar  16  is identified by the numeral  24 . The forward face  22  of collar  14  is provided with a circumferential slot  26  and in like manner, forward face  24  of collar  16  has a circumferential slot  28 . The collars  14  and  16  have rearward faces  30  and  32  where welds  18  and  20  are performed. 
     Positioned within circumferential slot  26  is a circumferential elastomeric seal  34  and in circumferential slot  28  a circumferential elastomeric seal  36 . 
     To provide containment of any fluid, whether liquid or gas, within pipeline  10 ,  12  a containment housing consisting of a lower portion  38  and a corresponding containment housing upper portion  40  is secured to collars  14  and  16  by welds  42 . The containment housing upper portion  40  has an opening therein to which is secured a flange  44  of the type to which various piping fittings or valves can be secured by bolts (not shown). 
     Positioned within passageway  46  within flange  44  is a pipe sealing assembly  48  that is illustrated and described in detail in U.S. Pat. No. 7,270,139 which is incorporated herein by reference. The invention herein is not concerned with details of the pipe sealing assembly  48  but instead the essence of this invention is a method of forming seal around the external circumferential surface pipeline  10 ,  12  as a method of closing off fluid flow through the pipeline. Essentially the pipe sealing assembly  48  includes a top support  50  and a lower support  52 . 
     Positioned between top support  50  and lower support  52 , that are retained by vertical shaft  54 , is a first seal cup  56  and, opposed to it, a second seal cup  58 . 
     As seen in  FIG. 2 , first seal cup  56  has upwardly extending arms  60  that are supported to a first roller  62 . Seal cup  58  has upwardly extending arms  64  that are supported to a second roller  66 . As seen in  FIG. 1 , first seal cup  56  has downwardly extending arms  68  while second seal cup  58  has downwardly extending arms  70 . These downwardly extending arms  68  and  70  are supported to lower rollers  72  and  74 . As seen in  FIG. 2 , lower support  52  has a pair of cam slots  75  and  76  that receives lower rollers  72  and  74 . In like manner, top support  50  has a pair of cam slots  78  and  80  that receives upper rollers  62  and  66 . When top support  50  is moved in a direction away from lower support  52 , rollers  62 ,  66 ,  72  and  74  acting in the cam slots  75 ,  76 ,  78  and  80  serve to deflect seal cups  56  and  58  toward each other and when top and bottom supports  50  and  52  move towards each other, seal cups  56  and  58  are forced away from each other. 
     Received on shaft  54  and compressibly positioned between lower support  52  and top support  50  is a compression spring  82 . The downward translation of shaft guide  84  and top plate  86  and with it first and second wedge members  88  and  90 , forces top support  50  towards lower support  52  compressing spring  82  and moving the top roller  62  and  66  within the cam formed in top support  50  and bottom rollers  72  and  74  within the cam formed in lower support  52 . This cam action causes first and second seal cups  56  and  58  to displace outwardly with respect to each other. The downward movement of lower support  52  is limited by a stop post  92  affixed to the interior of containment housing lower portion  38 . 
     First seal cup  56  has on its forward face a circumferential recess  94 . In like manner, second seal cup  58  has in its forward face a circumferential recess  96 . The function of recesses  94  and  96  are to receive the outer ends of pipe portions  10  and  12  respectively as seal cups  56  and  58  are expanded outwardly with respect to each other. This allows a circumferential sealing surface  102  on first seal cup  56  and a corresponding circumferential sealing surface  104  on sealing cup  58  to simultaneously engage circumferential elastomeric seals  34  and  36 . 
     When seal cups  56  and  58  are displaced away from each other circumferential sealing surface  102  of first seal cup  56  and circumferential sealing surface  104  of second seal cup  58  simultaneously engage circumferential elastomeric seals  34 ,  36 . This engagement closes communication between the interior of pipeline portions  10  and  12  thereby blocking fluid flow through the pipeline. When circumferential sealing surfaces  102  and  104  engage circumferential elastomeric seals  34  and  36  they simultaneously compress the elastomeric seals to increase sealing pressure against the external circumferential surface of pipe portions  10  and  12 . When the pipe sealing assembly  48  as shown in  FIGS. 1 ,  2  and  3  is upwardly withdrawn, the seal cups  56  and  58  are removed to leave fluid flow through pipe portions  10  and  12  unobstructed. 
       FIG. 3  shows an alternate arrangement for the invention wherein, rather in a spherical containment housing as shown in  FIGS. 1 and 2 , containment is achieved by the use of a lower containment portion  106  and an upper containment portion  108 . While not illustrated in the drawings these containment housing portions are each formed by two halves that are welded together and simultaneously welded to collars  110  and  112 . While the cross-sectional configuration of collars  110  and  112  are completely different than collars  14  and  16  as seen in  FIGS. 1 and 2 , the basic functions are the same.  FIG. 3  collars  110  and  112  are each trapezoidal and have frusto-conical surfaces  114  facing in the direction towards seal cups  56  and  58 . 
     A further difference between  FIG. 3  and the embodiment of  FIGS. 1 and 2  is that in  FIG. 3  the circumferential elastomeric seals  116  and  118  are trapezoidal to form a mating relationship with collars  110  and  112 . In the arrangement of  FIG. 3  as the seal cups  56  and  58  advance away from each other their circumferential sealing surfaces  102  and  104  compress circumferential seals  116  and  118  into sealing contact with collars  110  and  112  and, in addition, because of the angular relationship between the circumferential seals and the collars, the elastomeric seals are radially inwardly depressed relative to pipe portions  10  and  12  to effect increase sealing with the exterior of the pipe portions  10  and  12 . 
       FIG. 4  shows an alternate embodiment of the invention which functions in the same way as the embodiments shown in  FIGS. 1 through 3  except that a different system is employed to force seal cups  56  and  58  away from each other and into sealing engagement with circumferential elastomeric seals  34  and  36  held in position by collars  14  and  16 . Whereas the embodiments of  FIGS. 1 ,  2  and  3  utilize mechanical forces to urge seal cups  56  and  58  in directions towards collars  14  and  16 , in the embodiment of  FIG. 4  hydraulic force is employed.  FIG. 4  shows a tubular housing  120  extending upwardly from flange  44 . Positioned between seal cups  56  and  58  is a double ended hydraulic cylinder  122 . Extending downwardly from the exterior of cylinder  122 , a positioning element  124  that has a recess  126  in the lower end thereof, the recess receiving the upper end of stop post  92 . The function of the cooperative relationship between stop post  92  and positioning member  124  is to accurately locate double ended hydraulic cylinder  122  in alignment with pipe ends  10  and  12 . 
     Extending from opposed ends of double ended cylinder  122  are pistons  128  and  130 . From a source of hydraulic fluid pressure  132  (not shown), a flexible hose  134  conveys fluid pressure to an inlet  136  of double ended hydraulic cylinder  122  so that when hydraulic force is applied by fluid through hydraulic hose  134  cylinders  128  and  130  are simultaneously forced outwardly in opposed directions to apply force against first and second seal cups  56  and  58 . Thus the double ended hydraulic cylinder  122  with opposed pistons  128  and  130  provide the same action as is provided by pipe sealing assembly  48  in  FIGS. 1 ,  2  and  3 . 
     Each of  FIGS. 5 through 8  functions in essentially the same way as the embodiments of  FIGS. 1 through 4  except that in each of  FIGS. 5 ,  6 ,  7  and  8  modifications are made in the interrelationship between the collars, the forward end the seal cups and the arrangement of the circumferential seals. 
     In  FIG. 5  the circumferential collar  138  surrounding pipe portion  10  and to which upper and lower portions of containment housing  38  and  40  are welded is square in cross-sectional configuration. Collar  138  has a forward face  141  that extends radially of the axis of pipe section  10 . In  FIG. 5  seal cup  56 A has a forward face  140  with an internal circumferential slot  142  having a circumferential inclined surface  144  that engages a circumferential elastomeric seal  146 . The arrangement of internal circumferential slot  142  serves to capture elastomeric seal  146  and to compress it into sealed engagement between the forward face  141  of collar  138  and the exterior surface of the pipe  10 . Further the arrangement of  FIG. 5  is different from that in  FIGS. 1 ,  2  and  3  in that the circumferential elastomeric seal  146  has cloth  148  on its forward surface where contact is made with collar  138 . A further difference is that in the embodiment of  FIG. 5  a snap ring  150  is positioned in circumferential slot  142  to provide backup for circumferential elastomeric seal  146 . The arrangement of  FIG. 5  provides compressive containment of circumferential elastomeric seal  146  as seal cup  56 A applies compressive force to form a seal engagement between seal cup  56 A and the exterior surface of pipe  10 . 
       FIG. 6  shows an embodiment wherein the collar  138 A has a forward face with a circumferential notch  142 A as shown in the forward face of collar  14  of  FIGS. 2 and 4 . However,  FIG. 6  shows the arrangement wherein the circumferential elastomeric seal  36 A has a forward cloth face  148  as shown in  FIG. 5  plus a rearward cloth face  152 . The double cloth faces  148  and  152  of  FIG. 6  provides a circumferential elastomeric seal  36 A having a greatly improved dimensional stability. 
       FIGS. 7 and 8  show additional alternate embodiments of the manner in which elastomeric seals can be employed in a plugging tool that seals against the exterior surface of a pipe. In  FIG. 7  collar  138 A is the same as collar  138 A of  FIG. 6  and has an internal circumferential slot that receives a circumferential elastomeric seal  146 A that has, confined within the elastomeric seal an anti-extrusion spring  154 . This coiled anti-extrusion spring  154  reinforces the internal circumferential edge of the elastomeric seal to reduce the extrusion of the seal into the space between the exterior of pipe  10  and the interior surface  156  of the circumferential slot provided in seal cup  56 B. 
       FIG. 8  has the improvements and advantageous of  FIG. 7  plus the provision of a forward cloth face  158  affixed to circumferential seal  146 A. In addition,  FIG. 8  employs the advantageous of an anti-extrusion spring  154  as has been described with reference to  FIG. 7 .  FIG. 8  shows the advantageous of the combination of an anti-extrusion spring and a cloth surface to reinforce circumferential elastomeric seal  146 A. 
     As previously stated the invention herein is similar in many respects to the cam-assisted, wedge actuated, metal-to-metal seal, block and bleed plug tool of U.S. Pat. No. 7,270,138 with an important distinction and that is the patent teaches a block and bleed tool in which sealing is achieved by contact of metal sealing cups with metal collars, that is, metal-to-metal sealing. Whereas the present invention provides for the use of both elastomeric and metal seals and particularly provides for the unique concept of applying these seals to the exterior surface of pipe to secure a leak-proof block and bleed plugging tool. Applying seals to the exterior surface of a pipe have an important advantage compared to applying seals directly to ends of pipe or to the internal surface of pipe. This improvement is achieved since the outside surface of the pipe can be thoroughly cleaned of rust, debris, irregularities and so forth to thereby greatly improve the effectiveness of an apparatus to form leak-proof closure of the pipe. The invention herein provides improved and unique ways of using an elastomeric or a metal seal against the pipe exterior surface that achieves more consistent and superior results to other types of double block and bleed sealing systems. 
     While  FIGS. 1 through 8  illustrate apparatuses, systems and methods of providing block and bleed of a pipeline by using elastomeric seals on the exterior of the pipeline,  FIGS. 9 through 16  show such tools, apparatuses, systems and methods for sealing exposed ends of a pipeline by employing metal ferrules secured to the pipeline exterior. 
     As shown in  FIG. 9 , a metallic ferrule  160  is removably supported to the forward face of first seal cup  56 . To removably retain ferrule  160  on the forward surface of seal cup  56 , a plurality of radially spaced apart retainers  162  are employed. Each retainer is an elongated metallic clip that is secured to the external circumferential surface of first seal cup  56  and held in place by a threaded bolt  164 . Each of the retainers  162  has a recess  166  adjacent its forward end. Retainers  162  are flexible so that metallic ferrules  160  are held in position so that they can be advanced over the end of a cut length of pipeline but after the fenules are secured in position on the exterior surface of the pipeline, the seal cup  56  can be withdrawn, leaving the ferrules  160  in position on the pipeline. 
       FIG. 10  shows the first and second seal cups  56  and  58  deployed to seal against the portions of the pipeline  10  and  12 . The ferrules  160  are crimped to the frusto-conical forward faces  168  of the first and second collar  14  and  16  and the exterior surface of the pipeline. 
       FIG. 11  shows a seal cup  56  in position to insert a ferrule  160  onto the end of the pipeline while  FIG. 12  shows the relationship of the seal cup  56  after the ferrule  160  has been positioned on the exterior surface of the pipeline and in contact with the forward face  168  of first collar  14 .  FIG. 12  shows the ferrule  160  in position on the outer exterior end  10  of a pipeline which has been cut into and with the ferrule  160  in position to be crimped. 
       FIG. 13  shows force being applied against seal cups  56  to crimp the malleable metallic ferrule  160  so that it is permanently deformed to engage the exterior surface of pipe  10  and simultaneously to sealably engage the forward face  168  of collar  14 . 
     Ferrule  160  is metallic and is preferably of a malleable material that can, with sufficient force and pressure, be deformed to sealably contact the exterior surface of pipe  10  and simultaneously the forward surface  168  of collar  14 . 
       FIG. 14  shows the ferrule  160  as having been permanently deformed into sealing engagement with the exterior surface of pipe  10  and forward face  168  of collar  14 . 
       FIG. 15  illustrates how the retainers  162  release the ferrule  160  as the seal cup  56  is retracted from the portion of the pipeline  10 . The ferrule  160  remains crimped to the exterior surface of the portion of pipeline  10  and the forward face  168  of the collar  14 . 
       FIG. 16  shows a slightly alternate embodiment involving collar  14  in which, rather than having a frusto-conical forward face  168  as in  FIGS. 10 through 15  has a planar radial face  170 . The embodiment of  FIG. 16  illustrates that the face configuration for collar  14  can vary as required to ensure effective distortion of ferrule  160  by the application of pressure against seal cup  56 . 
       FIG. 16  shows an additional alternate embodiment in the configuration of retainer  162 . In  FIG. 16  the retainer  162  is thinner in the rearward direction while nevertheless providing a retention recess  166  so that ferrule  160  is retained in position as it is carried forward in the initial stages of the process of inserting the ferrule forward onto the end of a pipe as illustrated. The retainers  162  are essentially configured like a leaf-spring so they can flex within their elastic limit to retain a ferule in position to position it onto the end of a pipeline and hold it in such position as pressure is applied to deform the ferrule into permanent sealing engagement with the exterior of the pipeline and with a forward face of the collar which it contacts but nevertheless the spring tension is such that as the seal cup  56  is withdrawn as shown in  FIGS. 14 and 15 , the springs easily deflect to leave the deformed ferrule circumferentially surrounding the pipe  10  and in sealed engagement with the forward face of collar  14 . 
     The invention herein has been illustrated to show how external seals can be employed to provide block and bleed functions to a pipeline that has been cut to allow fluid flow through the pipeline to be blocked wherein sealing is achieved by elastomeric members that require less forceful pressure to achieve sealing or by metallic members, such as the metallic ferrule illustrated and described herein wherein greater application pressure is required but thereby providing a closing system that is effective to maintain pipe closure even in the presence of high temperature, such as a fire. Further the use of a metal ferrule sealing system achieves longer life expectancy of the closure system since, unlike some elastomerics the ferrules used in practicing this invention may be of metals and alloys that can withstand the application to which they are put for extended periods of time. A period of time may be the life expectancy of the pipeline on which the invention herein is utilized. 
     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.
The present invention is a method of plugging a pipeline having an exterior surface including the steps of affixing to the exterior of the pipeline first and second spaced apart collars, welding each collar to the pipeline so that an operating space is provided between the collars, positioning a seal with each collar, affixing a containment housing to the opposed collars providing a confined space around the pipeline and surrounding the operating space between the collars, the confined space being accessed by a passageway, cutting and removing a length of pipeline between the collars providing opposed pipeline exterior end surfaces, positioning first and second seal cups between the collars, each seal cup having a forwardly extending circumferential lip of internal diameter greater than the external diameter of the pipeline, and applying force to move the seal cups away from each other, the circumferential lips of the seal cups engaging with the opposed seals to compress them into sealing engagement with the collars and with the pipeline exterior surfaces.