Abstract:
A hydraulic plunger installation tool that exerts a hydraulic force on a plunger for a reciprocating pump to install the plunger into a pump cylinder opening. Maintenance of the pump typically includes repacking of the packing that surrounds the plunger and revalving of the pump&#39;s inlet and outlet valve. To allow repacking or revalving, the pump is disassembled and the plunger is removed. The hydraulic plunger installation tool is located at the pump cylinder on an upward facing nest with legs that provide a reaction point for a hydraulically actuated piston rod that is driven at one end by a hydraulic piston and engages the plunger at an opposite end during installation to push the plunger into the cylinder opening without the use of hammers by personnel.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority to provisional application 61/232,269, filed Aug. 7, 2009. 
     
    
     FIELD OF THE INVENTION 
       [0002]    This invention relates in general to plungers used in reciprocating pumps, and, in particular, to a hydraulic tool for installing a plunger. 
       BACKGROUND OF THE INVENTION 
       [0003]    Various kinds of pumps can be used in oilfield operations. One type of pump, for example, is a reciprocating pump. The reciprocating pump can be used to pump fluid such as chemicals, cement, or other media into a well. Reciprocating pumps typically increase the pressure within a cylinder by reciprocating a plunger longitudinally within the cylinder. Packing is generally used around the plunger and the plunger reciprocates as a crankshaft located within the pump rotates. As the plunger moves away from the cylinder, the pressure of the fluid inside chamber decreases creating a differential pressure across an inlet valve that allows the fluid to enter the cylinder. As plunger moves longitudinally towards the cylinder, the pressure of the fluid inside of the cylinder increases until the differential pressure across an outlet valve opens the outlet valve and allows fluid to exit cylinder. 
         [0004]    Maintenance of the pump, typically includes repacking of the packing surrounding the plunger and revalving of the inlet and outlet valves mentioned above. To allow repacking or revalving, the pump is disassembled by removing a suction cover plate and removing the plunger, which can be quite heavy. Additional pump components, such as connecting rods and pony rods may need to be stroked out to push out the plunger. However, during assembly of the pump, the plunger must be reinstalled. The plunger is heavy and requires much effort to push it back into the cylinder through the packing elements. Frequently, installing the plunger requires maintenance personnel to hammer the plunger into place during installation, potentially damaging pump parts or injuring personnel. 
         [0005]    Thus, installation of the plunger into the cylinder is time consuming, labor intensive, and potentially unsafe to personnel. 
         [0006]    Thus, a technique would be desired that makes pump maintenance and plunger installation safer, less time consuming, and less labor intensive. 
       SUMMARY OF THE INVENTION 
       [0007]    In an embodiment of the present invention, a hydraulic rod plunger installation tool is connected to a pump after maintenance is complete. The tool includes a piston and a piston rod that extends into a cylinder opening. The cylinder opening is covered by a suction cover plate during operation and has threads on an interior surface. A rail can be temporarily attached to the cylinder opening on which the hydraulic piston can be secured during the installation of the plunger, providing a reaction point for the piston. The tool further comprises a plurality of legs attached to the piston that engage the rail during installation of the plunger. 
         [0008]    In an embodiment of the present invention, the piston rod of the hydraulic plunger installation tool further comprises a plurality of telescoping stages such that one stage is embedded within another stage and have a combined area of A 1 . The hydraulic piston rod may generate sufficient force, in an example, at least 1000 lbs, to push the plunger into the packing. The piston rod has an end that can engage the plunger to thereby transfer a distributed force axially the plunger. 
         [0009]    During installation of the plunger the plunger is placed at the cylinder opening and the hydraulic plunger installation tool is mounted onto the pump. Hydraulic fluid can be connected to the cylinder of the tool to provide hydraulic power that can be exerted on the piston rod and consequently on the plunger. The installation tool advantageously generates sufficient force, in one example at least 1000 psi, to push the plunger into place. Once the plunger is properly in place within the pump cylinder, the hydraulic installation tool can be backed out of the cylinder opening and the plunger installation tool can then be removed for storage, allowing the suction cover plate to be placed back on the cylinder opening. 
         [0010]    The hydraulic plunger installation tool thus advantageously provides a safer way to maintain and disassemble pumps because the plunger installation tool, rather than a hammer, can be used to push the plunger back into position within the pump cylinder. This also results in a less time consuming, potentially less damaged parts, and a less labor intensive method of maintaining and disassembling the pumps as hammering of the heavy plunger is eliminated. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]      FIG. 1  is an illustration of a reciprocating pump in the prior art; 
           [0012]      FIG. 2  is an illustration of the plunger location within the cylinder portion of the pump shown in  FIG. 1 ; 
           [0013]      FIG. 3  is an enlarged perspective view of one embodiment of the hydraulic tool used to install the plunger back into the cylinder opening, constructed in accordance with the invention. 
           [0014]      FIG. 4  is an illustration of one embodiment of the hydraulic tool in a retracted position, constructed in accordance with the invention. 
           [0015]      FIG. 5  is an illustration of one embodiment of the hydraulic tool in an extended position, constructed in accordance with the invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0016]    Referring to  FIGS. 1 and 2 , reciprocating pump assembly or pump  12  includes a crankshaft housing  13  that comprises a majority of the outer surface of reciprocating pump  12 . Stay rods  15  connect crankshaft housing  13  to a cylinder housing  17  having a set of cylinders  37  ( FIG. 2 ). Each cylinder  17  is in communication with a fluid inlet  19  and a fluid outlet  21 . As shown in  FIG. 2 , a retaining nut  22  connects to an end of each cylinder  37  opposite the housing that houses the stay rods  15 . Pump  12  can be free-standing on the ground, can be mounted to a trailer that can be towed between operational sites, or mounted to a skid such as for offshore operations. 
         [0017]    Referring to  FIG. 2 , a portion of reciprocating pump  12  housed within crankshaft housing  13  is shown in a side partial sectional view. Crankshaft housing  13  houses a crankshaft  25 , which is typically mechanically connected to a motor (not shown). The motor rotates crankshaft  25  in order to drive reciprocating pump  12 . In one embodiment, crankshaft  25  is cammed so that fluid is pumped from each cylinder  37  at alternating times. As is readily appreciable by those skilled in the art, alternating the cycles of pumping fluid from each of cylinders  37  helps minimize the primary, secondary, and tertiary (et al.) forces associated with reciprocating pump  12 . 
         [0018]    A gear  24  is mechanically connected to crankshaft  25 , that is rotated by the motor through gears  26  and  24 . A connector rod  27  is connected to the crankshaft  25  at one end. The connector rod  27  connects to a crosshead  29  through a crosshead wrist pin  31 , which holds connector rod  27  longitudinally relative to crosshead  29 . The connector rod  27  pivots within a crosshead bushing  34  in the crosshead  29  as crankshaft  25  rotates with the other end of connector rod  27 . A pony rod  33  extends from crosshead  29  in a longitudinally opposite direction from crankshaft  25 . Connector rod  27  and crosshead  29  convert rotational movement of crankshaft  25  into longitudinal movement of pony rod  33 . 
         [0019]    A plunger  35  is connected to pony rod  33  for pumping the fluid passing through cylinder  37 . Packing  36  surrounds plunger  35 . A packing nut  38  is threaded into the cylinder housing  17 , and acts to maintain the packing  36  in the proper position within packing bore  37 . Cylinder  37  leads to an interior or cylinder chamber  39 , which is where plunger  35  pressurizes the fluid being pumped by reciprocating pump  12  ( FIG. 1 ). Cylinder  37  also typically includes an inlet valve  41  and an outlet valve  43 . Valves  41  and  43  are usually spring-loaded valves and are actuated by a predetermined differential pressure. Inlet valve  41  actuates to control fluid flow through fluid inlet  19  into cylinder chamber  39 , and outlet valve  43  actuates to control fluid flow through fluid outlet  21  from cylinder chamber  39 . 
         [0020]    Plunger  35  reciprocates, or moves longitudinally toward and away from cylinder chamber  39 , as crankshaft  25  rotates. As plunger  35  moves longitudinally away from cylinder chamber  39 , the pressure of the fluid inside chamber  39  decreases, creating a differential pressure across inlet valve  41 , which actuates valve  41  and allows the fluid to enter cylinder chamber  39  from fluid inlet  19 . The fluid being pumped enters cylinder chamber  39  as plunger  35  continues to move longitudinally away from cylinder chamber  39  until the pressure difference between the fluid inside chamber  39  and the fluid in fluid inlet  19  is small enough for inlet valve  41  to actuate to its closed position. As plunger  35  begins to move longitudinally towards cylinder chamber  39 , the pressure on the fluid inside of cylinder chamber  39  begins to increase. Fluid pressure inside cylinder chamber  39  continues to increase as plunger  35  approaches cylinder chamber  39  until the differential pressure across outlet valve  43  is large enough to actuate valve  43  and allow the fluid to exit cylinder  17  through fluid outlet  21 . In one embodiment, fluid is only pumped across one side of plunger  35 , therefore reciprocating pump  12  is a single-acting reciprocating pump. 
         [0021]    Maintenance of the pump  12 , typically includes repacking of the packing  36  surrounding the plunger  35  and revalving of the inlet and outlet valves  41 ,  43 . To allow repacking or revalving, the pump  12  is disassembled by removing the plunger clamp  46 , packing nut  38 , suction cover  44 , valve stop  45 , retaining nut  22 , and removing the plunger  35 . The connector rod  27  and pony rod  33  can be stroked out to slide the plunger  35  out and provide access to the packing  36  and valves  41 ,  43 . Repacking and revalving, typically require two people as the plunger  35  is heavy and must be re-installed into the pump  12  after maintenance is complete. Frequently, installing the plunger  35  requires maintenance personnel to hammer the plunger into place during installation. This approach to reinstall the plunger  35  can damage pump  12  parts and injure personnel. 
         [0022]    Referring to  FIG. 3 , an embodiment of a hydraulic installation tool  50  is shown. The hydraulic installation tool can be placed proximately to the pump  12  after maintenance is complete and can be connected to a hydraulic source  51  via a hydraulic connection  53  located on a base  59  of a housing  55  that can support a hydraulic cylinder  56 . The connection features can also be incorporated directly onto the hydraulic cylinder  56 . The hydraulic installation tool  50  can have a plurality of legs  52  connected to the housing  55  that allow the tool to slidingly engage rails on a rail guide  54  removably attached to cylinder housing  17  via a threaded mating end  62  screwed into the cylinder opening  60 . The new packing  38  ( FIG. 2 ) is installed prior to the use of the installation tool  50 . The tool  50  includes a hydraulic cylinder  56  with a piston rod  58  that can extend out from the body of the hydraulic cylinder  56  during operation. An engagement end  57  of the piston rod  58  can engage one end of the plunger  35  to force the plunger  35  into the pump cylinder housing  17  through the cylinder opening  60  located where the retaining nut  22  ( FIG. 2 ) was removed. 
         [0023]      FIGS. 4 and 5  show telescoping stages  58   a  and  58   b  of the piston rod  58 . The respective lower surfaces of the stage  58   b  and embedded stage  58   a  have a combined area of A 1 . Stage  58   b  is annular and stage  58   a  telescopingly extends from within 58b in response to hydraulic fluid acting on area A 2  once a flange  70  on an exterior surface of stage  58   b  contacts a downward facing shoulder within cylinder  56 . Although the flange  70  is shown located at a base of stage  58   b , flange  70  could be located at any desired point along the length of the stage  58   b  in order to achieve a desired force, such as for example 2000 lbs, through a desired distance. Once under load from the plunger  35 , the piston rod  58  can generate a sufficient force, such as for example, at least 2000 lbs, to push the plunger  35  into the packing  36  ( FIG. 2 ). The 2000 lbs force is only required through approximately one inch, which is why the flange  70  can be located at a point on the stage  58   b  other than the base. Generating this force is accomplished by supplying hydraulic fluid from the hydraulic source  51  to the hydraulic cylinder  56  through the hydraulic connection  53  acting on the combined area A 1  of piston  58   a  and piston  58   b . Piston  58   b  is limited to deliver a low stroke rate and distance that is required for the initial higher load. Once through the initial stage of the packing  36  ( FIG. 2 ), the force of the hydraulic fluid acts on the smaller area A 2  to thereby cause piston rod stage  58   a  to telescope out at a faster rate than stage  58   b . For example, the length L of stage  58  is set so when it is fully extended from the hydraulic cylinder  56 , its terminal end is at or past the packing  36 . To create the required reaction points, the legs  52  ( FIG. 3 ) can be locked to the rail guide  54  ( FIG. 3 ) in any number of ways. For example, the legs  52  may fit into recesses or slots  66  ( FIG. 3 ) formed on the rail guide  54  ( FIG. 3 ) and the guide  54  can temporarily engage the body of the pump cylinder  17  via the mating end  62 . The slots  66  may lockingly secure the legs  52  of the cylinder housing  55  for example, with locking pins (not shown). Alternatively, the legs  52  can lock onto a groove  64  formed along the length of the rail guide  54 . The rail guide  54  may also have a concave shape that provides a more effective surface on which to support the installation tool  50 . After the plunger  35  is properly in place within the pump cylinder  17 , the piston rod  58  can be retracted into the hydraulic cylinder  56 . The hydraulic installation tool  50  along with the rail guide  54  can then be removed for storage and the retaining nut  22  placed back on the cylinder opening  60 . 
         [0024]    Reciprocating pumps  12  are large, and complex pieces of equipment with many parts that may have to be replaced as they wear out. Making the disassembly safer, simpler, and less time consuming is thus desirable because it makes pump maintenance safer and less labor intensive. By using a hydraulic installation tool  50  that can install the plunger  35  back into the pump  12  via hydraulic actuation, the need for manually hammering the plunger  35  into place is eliminated. Thus, the dangerous and labor intensive task of installing the plunger  35  back into the pump  12  after completion of maintenance, is eliminated. 
         [0025]    This written description uses examples to disclose the invention, including the best mode, and also enable a person of ordinary skill in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. These embodiments are not intended to limit the scope of the invention. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.