Abstract:
A device for indicating the passage of a pig beyond a predetermined location in a pipeline comprising a pig detector connected to a pipeline and communicating with the interior of the pipeline through an opening at the location. A means for divorcing the pressure inside the pipeline from the pressure outside the pig. A trigger mounted in the pig detector and adapted to project into the interior of the pipeline through the opening, an indicator associated with the pig detector, a cylindrical indicator being slidably mounted within the indicator housing, catch fingers mounted in the housing for movement toward and away from the central axis of the housing, a catch spring for urging the fingers towards the central axis, an indicator spring mounted within the housing for urging the indicator beyond the indicator housing so as to be visible and to provide an indication that a pig has passed.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     None. 
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     None. 
     THE NAMES OF THE PARTIES TO A JOINT RESEARCH AGREEMENT 
     None. 
     REFERENCE TO A “SEQUENCE LISTING,” A TABLE, OR A COMPUTER PROGRAM LISTING APPENDIX SUBMITTED ON COMPACT DISC AND AN INCORPORATION-BY-REFERENCE OF THE MATERIAL ON THE COMPACT DISC 
     None. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to devices for determining the position of a pipeline pig in a pipeline. More particularly, the present invention relates to an apparatus for signaling the passage of a pipeline pig beyond a predetermined point or points in a pipeline. 
     2. Description of Related Art 
     Existing art utilizes a spring to hold a triggering mechanism downward when subjected to the internal pressure of the pipeline when installed. The force the spring is designed to hold is directly dictated by the pressure in the pipeline. Thus, a range of springs are used depending on the anticipated pressure range of the pipeline. 
     A problem with the existing art is that if the pipeline pressure falls below the anticipated range of the spring in use, the triggering mechanism can remain in the downward position when a pig passes. Conversely, if the pipeline pressure is greater than anticipated, the spring will not be strong enough to hold the triggering mechanism in place against the pressure of the pipeline. 
     To overcome these problems, the active portions of the triggering mechanism are isolated from the pressure inside the pipeline via o-rings and a bypass port. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention relates to a pig detector that is adapted to be mounted on the outside of a pipeline for the purpose of determining the passage of a pig past the point of attachment. The pig detector includes a pipe nipple connected to the pipeline and communicating with the interior of the pipeline through an opening. A trigger ball projects downwardly from the pipe nipple through the opening and into the interior of the pipeline and adapted to be contacted by a passing pig. The pipe nipple connects with an indicator housing in which a cylindrical indicator is vertically slidably mounted. Within the housing are mounted a plurality of catch fingers which are pivotal towards and away from the central axis of the housing and which are provided with catches. The trigger connects with an actuator which is positioned to bear against the sides of the catch finger to cause them to pivot outwardly away from each other when the actuator moves up vertically. The catch fingers are provided with a garter spring to urge them radially inwardly towards the central axis. The actuator is resiliently urged downwardly by an actuator spring so as to cause the trigger to protrude into the space in the pipeline. An indicator spring is mounted within the housing to resiliently urge the indicator upwardly beyond the indicator housing so as to be visible and to provide indication that a pig has passed by. A lock pin is attached to the lower surface of the indicator and is provided with a pointed end which is adapted, when moved downwardly, to pry the catch fingers apart and also the lock pin is provided with an upper surface adapted to be engaged by the catches on the catch fingers to hold the indicator totally within the housing against the action of the second spring. When a pig moves in the pipeline past the trigger and actuates the trigger, the actuator will bear against the fingers and separate them radially against the action of the garter spring to release the lock pin and allow the indicator to move upwardly within the indicator housing so as to provide a visual indication that a pig has passed. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
       A preferred embodiment of the present invention is described in detail below with reference to the attached drawing figures, wherein: 
         FIG. 1  illustrates an elevation of the pig detector of the present invention showing the trigger element projecting inwardly into the pipeline. 
         FIG. 2  illustrates a view similar to  FIG. 1  but showing the trigger element in its upmost position, with the indicator also being elevated. 
         FIG. 3  illustrates a longitudinal sectional view taken along section line  3 - 3  of  FIG. 1 . 
         FIG. 4  illustrates a view similar to  FIG. 3  but showing the trigger being released by a pig. 
         FIG. 5  illustrates a longitudinal sectional view taken along section line  5 - 5  at a time slightly after the position shown in  FIG. 4 . 
         FIG. 6  illustrates an exploded view of the elements shown in  FIGS. 1 through 5  but with the catch fingers omitted. 
         FIG. 7  illustrates a transverse sectional view taken along section line  7 - 7  of  FIG. 3 . 
         FIG. 8  illustrates a transverse sectional view taken along section line  8 - 8  of  FIG. 5 , after the catch fingers have been returned to their original position by the garter spring. 
         FIG. 9  illustrates a transverse sectional view taken along section line  9 - 9  of  FIG. 3 . 
         FIG. 10  illustrates a transverse sectional view taken along section line  10 - 10  of  FIG. 3 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The embodiments discussed herein are merely illustrative of specific manners in which to make and use the invention and are not to be interpreted as limiting the scope of the instant invention. 
     Referring to the drawings in detail,  FIGS. 1 and 2  show a pig detector  10  comprised of a pipe nipple  12  which can be connected to the outside of a pipe  14  in any conventional manner, for example, by welding. The pipe  14  will have a hole  16  therein through which a ball (trigger)  18  protrudes. The ball  18  is connected to the internal components of the pig detector  10  in a manner later to be described. The exterior of the pig detector  10  also shows a collar  20 , an indicator housing  22  and a cap  26 . 
     In the position shown in  FIG. 1 , the ball  18  is in its lowermost position, indicating that a pig has not passed the location of the pig detector  10  so that the trigger  16  ball is not pushed upwardly. However, in the position shown in  FIG. 2 , the trigger ball  18  is disposed upwardly indicating that a pig has just passed, such that the internal mechanism has been actuated to release a cylinder  28  which is also referred to as an indicator. In  FIG. 2 , the indicator  28  merely indicates that a pig has passed by, and it can be very easily distinguished from the appearance of the pig detector in  FIG. 1 . 
     Referring now to  FIG. 3 , which is a longitudinal cross-section through the pig detector and the pipe  14 , the trigger ball  18  is connected to the lower end of the plunger  120  which connects with an actuator  115  through interconnecting trigger pins  119  and trigger pin plate  118 . The plunger  120  is adapted to be slidably received within the lower end of a housing arrangement which has a lower end  121  and an upper end  38 . The plunger  120 , the trigger plunger cap  122 , and the interconnecting trigger pins  119  and trigger pin plate  118  are all slidably received in the lower housing  121  which is interconnected to the upper housing  38  by various threaded means shown in the drawing. The various elements in the drawing located below housing  38  are all variously lubricated and O-rings  40  and  84  are provided. The lower housing is provided with a cylindrical recess  137  in which the plunger  120 , trigger plunger cap  122 , and interconnecting trigger pins  119  and trigger pin plate  118  are received. The trigger plunger cap  122  is provided with a cylindrical recess  147  in which the upper end of the plunger is received. The trigger plunger cap  122  is maintained in a fixed position when the upper housing  38  is threaded to the lower housing  121 . The interconnecting trigger pins  119  and trigger pin plate  118  are maintained in a vertically glidable position by slidably mating the trigger pins  119  with trigger plunger cap holes  157  provided in the trigger plunger cap  122 . The trigger pins  119  extend completely through the trigger plunger cap  122  ready to engage the plunger  120  when it is activated by the trigger ball  18 . The plunger  120  includes a lip  187  for alternately engaging a step in the lower housing recess  137  and trigger pins  119  depending on whether the trigger ball has been engaged. Two O-rings  123  are mounted in suitable peripheral grooves in the plunger  120 : one O-ring to engage and create a seal with the trigger plunger recess  147  and one O-ring to engage and create a seal with the lower housing recess  137 . The plunger  120  includes a bypass port  167  running from the top of the plunger to a point just above where the plunger is connected to the trigger ball  18  where the bypass port vents via several vent holes  177  on the periphery of the plunger  120 . 
     An O-ring  124  is mounted in a suitable groove in the top of the lower housing  121  creating a seal with the upper housing  38 . An O-ring  40  is mounted in a suitable peripheral groove in the upper housing  38  and a backup O-ring  84  is also mounted in the same groove immediately above the O-ring  40 . A helical spring  48  is received over the upper end of the actuator  115  and extends within the recess  42  down-wardly from the lower inside surface of the collar  20  to the lower surface of the actuator  115  for continually urging the trigger pin plate  118  and actuator  115  downwardly so that the ball  18  is also urged downwardly. 
     Above the top of the actuator  115  there is mounted a plurality of catch fingers  50  which are urged towards each other by means of a garter spring  52 . The tops of the fingers  50  are provided with catches  54  which are adapted to be received over the top of a pointed lock pin  56  which is threadedly received in the lower end of a cylindrical indicator  28 . The indicator  28  is slidably received within an indicator housing  22 . 
     Whereas, most the elements of the pig detector have been shown and described in relation to  FIGS. 1 to 3 ,  FIG. 6 , nevertheless, is an exploded view which shows the manner in which the various elements interconnect with each other as previously described in relation to  FIGS. 1-3 ;  FIG. 6  also illustrates additional elements not specifically shown in  FIGS. 1 to 3 . 
     Immediately above the collar  20  there is shown an O-ring  60  which is adapted to be received in a recess  62  located in the upper portion of the collar  20 , more particularly centrally in the bore which is provided for the actuator  115 . A catch plate  64  is provided for the catch fingers  50 . Catch finger pins  66  (three in number) are provided to permit pivoting of the fingers  50  in radial slots  74 . 
     Referring also to  FIG. 3 , in addition to  FIG. 6 , the upper end of the pointed lock pin  56  is threadedly received in a threaded opening at the bottom of the indicator  28 . Thus, when the lock pin  56  is engaged by the fingers  50 , as shown in  FIG. 3 , the indicator  28  is fully enclosed within the indicator housing  22  and an indicator spring  76  is compressed between the lower end of the indicator  28  and the catch plate  64 . Four button-head screws  78  pass through suitable holes in the indicator housing  22  and into the sides of the catch plate  64 . The catch plate  64 , in turn, is provided with a pair of button-head screws  70  which pass through suitable holes in the catch plate  64  and into holes in the collar  20  to hold them in a fixed position. The collar  20 , in turn, is provided with a brass tipped set screw  72  which secures the collar  20  onto the upper threaded end of the pipe nipple  12 . Immediately below the collar  20  and directly above the upper housing  38  is a pipe cap spacer  116  held into a fixed position on the underside of the collar  20  by pipe cap spacer bolts  117 . 
     Turning now to  FIG. 4 , when a pig  88  passes through the pipeline  14  and actuates the trigger  18 , the actuator  115  will move upwardly and engage the sides of the three catch fingers  50  causing them to pivot outwardly and release the lock pin  56 . At this time, the spring  76  commences to raise the indicator  28 .  FIG. 5  represents the condition of the pig detector  10  after the pig  88  has passes completely by. In the  FIG. 5  position the spring  76  has raised the indicator  28  to its uppermost position so that it serves as a signal to anyone looking that way that the pig has passed this particular pig detector. At the same time, the spring  48  moves the trigger  18  back to its original position and the garter spring  52  will move the fingers  50  back to their original position. If it is desired to recock the pig detector, all one needs to do is push downwardly on the cap  26  until the lock pin  56  is engaged by the catches  54  at the tops of the catch fingers  50 . 
       FIGS. 7 and 8  relate to enlarged details of the catch finger assembly.  FIG. 7  is a sectional view taken along section line  7 - 7  of  FIG. 3 , showing the catch fingers  50  in engagement with the lock pin  56 . Note that the fingers  50  are urged pivotally inwardly towards each other by means of the garter spring  52  which encircles the fingers midway of their ends.  FIG. 8  is a sectional view taken along section line  8 - 8  of  FIG. 5  after the lock pin  56  has been released. The garter spring  52  has returned the fingers  50  to their original position as shown in  FIG. 5  and the actuator  115  is bearing against the lower sides of the fingers.  FIGS. 7 and 8  also show three triangularly arranged holes or bores  67  which extend like chords across the catch plate  64  so as to receive therein the catch finger pins  66  which permit, the pivoting of the fingers  50  in the radial slots  74 . 
       FIG. 9  is a transverse sectional view taken along section line  9 - 9  of  FIG. 3  and cuts through the collar  20  roughly in the neighborhood of the set screw  72 . Housing  38  is shown separated from the pipe  12  by means of an annular space  41  which represents the recess in which the O-ring  40  and  84  are located. 
       FIG. 10  is a sectional view of the bottom end of the trigger  18  showing its attachment to the plunger  120 . The trigger  18  is provided with a transverse opening  90  which is in alignment with a transverse opening  92  in the plunger  120 . A pin  94  having a set screw  96  at one end thereof is adapted to pass through the opening  90  in the trigger  18  and also through the hole  92  in the plunger  120  to hold the trigger  18  in place. 
     While the invention has been described with a certain degree of particularity, it is to be noted that modifications may be made in the details of the invention&#39;s construction and the arrangement of its 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 the purposes of exemplification.