Abstract:
A switch arm assembly for a piggable pipeline connector, the assembly comprising a switch arm and a handle assembly. The handle assembly comprises shaft connecting a handle with the switch arm and a stop to prevent the shaft from moving substantially away from the switch arm should the shaft become disconnected from the switch arm. The stop may comprise a shoulder in the shaft to prevent the shaft from exiting a housing, a bonnet over the top of the handle, or both.

Description:
CROSS REFERENCE 
     Not Applicable. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates generally to a switch arm for a pipeline connector, and more particularly, but not by way of limitation, to an easily manufactured switch arm and method of manufacturing the same. 
     2. Description of the Related Art 
     Devices known as pigs are often used to perform maintenance and for other purposes within pipelines while the pipelines are in use. Pigs have a difficult time negotiating a sharp bend in a pipeline, such as those that can occur at the junction of more than one pipeline. Thus, to be piggable, pipelines sometimes employ Y-shaped junctions rather than T-shaped junctions, making the change in direction a gradual curve rather than a sharp corner. 
     A switch arm is often attached at the junction between the two outward bound pipelines to allow a user to direct the pig along whichever pipeline he or she desires. The user may turn an attached handle to angle the switch arm to block off one of the pipelines, allowing the pig to travel along the second pipeline, or may turn the handle the other way to block off the second pipeline, allowing the pig to travel along the first. 
     The contents of the pipeline may be under significant pressure. Thus, if the handle assembly is damaged or otherwise fails, elements of the handle assembly may be launched from the pipeline and become a danger to people in the vicinity. 
     Based on the foregoing, it is desirable to provide a handle assembly with safety features to prevent elements of the handle assembly from being dislodged by the pressure within the pipeline should the handle assembly become damaged. 
     It is further desirable for the safety features to include a shoulder and/or a safety bonnet to act as a mechanical stop. 
     SUMMARY OF THE INVENTION 
     In general, in a first aspect, the invention relates to a switch arm assembly comprising a switch arm and a handle assembly. The handle assembly may comprise a shaft with a first end and an opposed second end, where the first end is connected to the switch arm, and a stop preventing the shaft from moving substantially away from the switch arm should the shaft become disconnected from the switch arm. The switch arm may be located within a piggable pipeline connector. 
     The switch arm assembly may further comprise a housing with a top, where the first end of the shaft is located inside the housing, the shaft extends through an opening in the top of the housing, and the second end of the shaft is located outside the housing. The stop may comprise a shoulder in the shaft, where the shoulder is located below the top of the housing and where the shaft below the shoulder has a diameter larger than the opening in the top of the housing. Additionally or alternately, the stop may comprise a bonnet comprising: a first leg attached to the top of the housing and extending away from the housing parallel to the shaft; a second leg attached to the top of the housing and extending away from the housing parallel to the shaft and to the second leg; and a cross piece connecting the first leg and the second leg beyond the second end of the shaft such that the bonnet straddles the second end of the shaft. 
     The top of the housing may comprise a seal block. The switch arm assembly may further comprise a retainer pin, where the shaft is connected to the switch arm via the retainer pin. The switch arm may further comprise a handle connected to the second end of the shaft, where the shaft is perpendicular to the switch arm and the handle is perpendicular to the shaft and parallel to the switch arm. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a piggable pipeline connector with a switch arm handle assembly; 
         FIG. 2  is a cut away view of the piggable pipeline connector showing the switch arm and switch arm handle assembly, with the switch arm in a first position; 
         FIG. 3  is a cut away view of the piggable pipeline connector showing the switch arm and switch arm handle assembly, with the switch arm in a second position; 
         FIG. 4  is an exploded view of the switch arm and switch arm handle assembly; 
         FIG. 5  is a top cross sectional view of the piggable pipeline connector showing the switch arm in the second position and showing the switch arm in the first position in dashed lines; 
         FIG. 6  is a side cross sectional view of the switch arm handle assembly in place on the piggable pipeline connector; 
         FIG. 7  is a cross sectional view of the top of the switch arm handle assembly; 
         FIG. 8  is an exploded view of the top of the switch arm handle assembly with a safety bonnet; and 
         FIG. 9  is a cross sectional view of the top of the switch arm handle assembly with the safety bonnet in place. 
     
    
    
     Other advantages and features will be apparent from the following description and from the claims. 
     DETAILED DESCRIPTION OF THE INVENTION 
     The devices and methods discussed herein are merely illustrative of specific manners in which to make and use this invention and are not to be interpreted as limiting in scope. 
     While the devices and methods have been described with a certain degree of particularity, it is to be noted that many modifications may be made in the details of the construction and the arrangement of the devices and components without departing from the spirit and scope of this disclosure. It is understood that the devices and methods are not limited to the embodiments set forth herein for purposes of exemplification. 
     In general, in a first aspect, the invention relates to safety features for a handle assembly  100  for controlling a switch arm  1 . The switch arm  1  may be located within a piggable pipeline connector  6 , which may connect a single pipeline  7  to a plurality of pipelines  8 , such as pipelines  8   a  and  8   b  as shown. 
     The connector  6  may be Y-shaped, as shown in the drawings, or any other shape connector desired. For example, two pipelines  8  may travel perpendicular in opposite directions relative to pipeline  7 , one pipeline  8  may travel perpendicularly while another pipeline  8  continues in the same direction as pipeline  7 , one or more pipelines  8  may travel at any desired angle relative to pipeline  7 , two or more pipelines  8  may each travel at different angles relative to pipeline  7 , or any other desired configuration or combination of configurations. In general, the contents may flow from the single pipeline  7  to the plurality of pipelines  8 . The switch arm  1  may be used to direct a pig traveling through pipeline  7  into one particular pipeline  8 . 
     The connector  6  may join pipeline  7  at a point  9  and pipelines  8  at points  10 . Between points  9  and  10 , the connector  6  may branch out from junction  12  into a plurality of legs  11 , such as legs  11   a  and  11   b  as shown, each leg  11  leading toward one point  10 . The connector  6  may be straight or may gradually curve from point  9  to each point  10 , making the connector  6  fully piggable. The connector  6  may not have any 90° angles or any other sharp angles that would make passing a pig therethrough difficult or impossible. 
     The switch arm  1  may be elongate and may have a first end  20  and an opposed second end  21 . The first end  20  may be located at junction  12 , such that the switch arm  1  may block the entrance to either leg  11 , depending on the position of the switch arm  1 . The switch arm  1  may be pivotally connected to the connector  6  such that it may pivot between the two legs  11 . The switch arm  1  may be connected at its first end  20  to a handle assembly  22 , which the user may turn to change the position of the switch arm  1 . 
     The switch arm extension  2  may lie in the same plane as the switch arm  1 . It may be pivotally connected to the second end  21  of the switch arm  1  via the plates  3  and  4  and pin  5  as shown in  FIG. 4 . The switch arm extension  2  may taper to a point or a rounded point and may rotate sufficiently that the side of the switch arm  1  and the side of the switch arm extension  2  form a generally smooth surface with no sharp angles or edges upon which the pig could become stuck, as seen in  FIGS. 2, 3, and 5 . The right side of the switch arm  1  and the right side of the switch arm extension  2  may curve and/or taper appropriately to match the general curvature of the left side of the inside wall of connector  6  as it transitions into the right leg  11  of connector  6 . Thus, as seen in  FIG. 3 , the left side of the inside wall of connector  6 , the right side of the switch arm extension  2 , the right side of the switch arm  1 , and the left side of the inside wall of the right leg  11  may all form a generally smooth surface with no sharp angles or edges upon which the pig could become stuck. Similarly, the left side of the switch arm  1  and the left side of the switch arm extension  2  may curve and/or taper appropriately to match the general curvature of the right side of the inside wall of connector  6  as it transitions into the left leg  11  of connector  6 . Thus, as seen in  FIG. 2 , the right side of the inside wall of connector  6 , the left side of the switch arm extension  2 , the left side of the switch arm  1 , and the right side of the inside wall of the left leg  11  may all form a generally smooth surface with no sharp angles or edges upon which the pig could become stuck. Both positions of the switch arm  1  and switch arm extension  2  are shown in  FIG. 5 . 
     The handle assembly  22  may comprise a shaft  50 , which may connect to the switch arm  1  via a retainer pin  51  with a threaded head, or other attachment device. The shaft  50  may connect at its other end to a handle  52  via a screw  53  or other attachment device. Thus, turning the handle  52  may make the shaft  50  turn, which in turn may make the switch arm  1  pivot between the first position and the second position. The ends of the shaft  50  and switch arm  1  that connect together may be located within a housing  54  located at the junction  12 . The housing  54  may have an opening  55  at its end. A half collar  56  may be mounted at the end of the housing  54  surrounding the opening  55  and a plug  57  may screw into the half collar  56 , thus sealing off the opening  55 . 
     The shaft  50  may extend upward out of the top of the housing  54 . A shaft housing  58  may be attached to the top of the housing  54 , such as by welding, and may extend upward, surrounding the shaft  50  for the height of the shaft housing  58 . The shaft housing  58  may terminate in a base plate  59 . The base plate  59  may be attached to the shaft housing  58 , such as by welding, and may have a bore  60  therethrough. The shaft  50  may extend through the bore  60 . A seal block  61  may be attached to the top of the base plate  59 , such as via bolts  62  or other attachment devices. The seal block  61  may also have a bore  63  therethrough, where the bore  63  is coaxial with the bore  60 . The shaft  50  may extend through the bore  63 . The handle  52  may attach to the shaft  50  above the seal block  61 . A seal  64 , such as an O ring or other seal, may be located between the base plate  59  and the seal block  61 , and another seal  65 , such as an O ring or other seal, may be located within bore  63  between the seal block  61  and the shaft  50 . A grease button  66  may allow for lubrication of the seals  64  and  65 . 
     Bore  63  may have a smaller diameter than bore  60 . The shaft  50  may have a shoulder  67  located below the seal block  61 . The shaft  50  below the shoulder  67  may have a diameter greater than the diameter of bore  63  but less than the diameter of bore  60 . The shaft  50  above the shoulder  67  may have a diameter less than the diameter of bore  63 , provided the diameters of each and the diameter of the seal  65  are such that the shaft  50  may rotate within the bore  60  and the seal  65  but the interior of the handle assembly  22  is effectively sealed off. 
     The shoulder  67  may prevent the shaft  50  from traveling upward relative to the shaft housing  58  should the retainer pin  51  become damaged or otherwise ineffective. In the event of such a failure, the top of the shoulder  67  and the bottom of the seal block  61  may act as a mechanical stop to prevent a blowout due to pressure within the pipeline causing upward movement of the shaft  50  out of the shaft housing  58 . 
     Additionally or alternately, a safety bonnet  68  may be attached to the top of the seal block  61  via one or more of the bolts  62  or other attachment devices. The safety bonnet  68  may extend upward on either side of the shaft  50  and across the end thereof, allowing room for the handle  52  to be turned but preventing the shaft  50  from traveling upward relative to the shaft housing  58  should the retainer pin  51  become damaged or otherwise ineffective. In the event of such a failure, the safety bonnet  68  may act as a mechanical stop. The shaft  50  may travel upward until its end hits the safety bonnet  68 , and then may be prevented from further upward movement, thus preventing a blowout due to pressure within the pipeline causing upward movement of the shaft  50  out of the shaft housing  58 . 
     Either the shoulder  67  or the safety bonnet  68  may be used as a mechanical stop to prevent upward movement of the shaft  50 , or both the shoulder  67  and the safety bonnet  68  may be used together as redundant safety features. In particular, the safety bonnet  68  is suitable for retrofitting existing handle assemblies  22  as installation may require only removing two bolts  62 , placing the safety bonnet  68  in place over the end of the shaft  50 , and replacing the bolts  62  to secure the safety bonnet  68  in place relative to the seal block  61  and base plate  59 . 
     Whereas, the devices and methods have been described in relation to the drawings and claims, it should be understood that other and further modifications, apart from those shown or suggested herein, may be made within the spirit and scope of this invention.