Abstract:
A fluid end for a high pressure pump with improved resistance to fatigue failure is disclosed. Interior surfaces that are prone to fatigue failure are laser peened to resist cracking and other types of failures. A work holder for supporting the fluid end as it is peened is also disclosed.

Description:
BACKGROUND OF INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    This invention is for a fluid end for a high pressure fluid pump such as a pump used for supplying fracing fluid to an oil or gas well during a fracing procedure. Interior bore portions of the fluid end are laser peened to reduce the failure rate of the pumps due to interior cracks occurring at certain locations as the result of metal fatigue. 
         [0003]    2. Description of Related Art 
         [0004]    U.S. Pat. No. 7,484,452 discloses generally a high pressure pump with a fluid end  14 . Tension members  22  are provided to address the high stresses and the fatigue failure at regions  36  shown in  FIG. 4 . The patent also discloses other prior art techniques have included “shoot peening compressive stresses at the crack location.” 
         [0005]    U.S. Pat. No. 7,750,266 discloses the technique of laser peening a work part such as a wing skin for an airplane. A robot optical assembly  201  is mounted on a process platform  200  that can move along tracks  219 . U.S. Pat. No. 7,573,001 discloses an improved method for laser peening a work piece  311  which may be a turbine blade from a jet engine. The laser disclosed in U.S. Pat. No. 7,573,001 is said to be capable of providing as much as ten times greater energy with a plus duration of one tenth of the prior art. 
       BRIEF SUMMARY OF THE INVENTION 
       [0006]    The invention disclosed and claimed in this application is for an improved fluid end for a high pressure pump. Interior portions of the fluid flow channels are laser peened to improve their resistance to failure as the result of fatigue cracks formed within the fluid end at certain locations as will be discussed in more detail herein. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S) 
         [0007]      FIG. 1  is a perspective view of a high pressure pump. 
           [0008]      FIG. 2  is a perspective view of the fluid end of a high pressure pump. 
           [0009]      FIG. 3  is a perspective view of one of the fluid chambers in the fluid end. 
           [0010]      FIG. 4  is a sectional view of the interior of a fluid chamber. 
           [0011]      FIG. 5  is a perspective view of the holder for the fluid end used during the peening process 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0012]      FIG. 1  illustrates a typical high pressure pump that includes a power end  50  that houses a series of gears and rods, and a fluid end  10  which may be formed of 4330 steel. Fluid end  10  includes a plurality of upper and lower holes  14  and  15  for securing the fluid end to the power end as shown in  FIG. 3 . 
         [0013]    The fluid end as shown in  FIG. 2  comprises a body member  11  including five fluid pumping chambers  91  ( FIG. 4 ) each having an outlet bore  21  which is in fluid communication with a longitudinally extending outlet passageway  16 . A plurality of holes  9  surround passageway  16  for receiving threaded studs or bolts. Each fluid chamber  91  as shown in  FIG. 4  also includes an inlet bore  22  which is in fluid communication with a suction manifold  51 . The fluid end also includes a plurality of bores  23  that receive a power piston for compressing the fluid within the fluid chamber  91 . Each fluid chamber further includes an inlet and outlet valve at  22  and  21  respectively as is well known in the art. Experiences has shown that area  34 ,  35 ,  37 ,  43 ,  44 , and  47  identified in  FIG. 4  are subject to high rates of fatigue failure which results in cracks that render the pump inoperable. This causes extended down time for the fracing process and requires replacement of the fluid end both of which are very costly in terms of time and money. 
         [0014]    The invention of the instant application includes laser peening of these areas using the high power/low pulse time of the latest laser peening technology as disclosed above. 
         [0015]    In order to accomplish this, a work piece holder  61  as shown in  FIG. 5  for the fluid end has been developed. 
         [0016]    Work holder  61  includes two circular discs  62  attached to both ends of the fluid end  10  by bolts extending from holes  9  in the fluid end. The fluid end and discs are rotably supported by a pair of bearings  70  and bearing supports  72  on in a pair of A-shaped supports  64  that are rigidly connected to each other via support bars  65 . Openings  63  are provided in each of the discs to provide a handle for rotating the fluid end to the appropriate position. A retractable pin mechanism  68  is positioned on A-framed  64  which allows the pin to be inserted into one of the apertures  69  provided in the discs to allow the fluid end to be locked in a selected orientation. 
         [0017]    In accordance with the invention a laser device  71 , such as discussed above, is positioned such that the laser beam is directed through one of the bores  21 ,  22 , and  23  toward the interior surface that is accessible through the bore. 
         [0018]    Portion  35  of the fluid chamber  91  can be accessed by the laser through the piston bore  23 . Portion  37  of the fluid chamber can be accessed through inlet bore  22 . Portion  34  of the fluid chamber can be accessed through outlet bore  21 , and portion  47  can also be peened through outlet bore  21 . Portion  43  can be peened through outlet bore  12 . Portion  44  can be peened through piston bore  23 . 
         [0019]    Suitable apparatus for peening the fluid end is disclosed in U.S. Pat. Nos. 7,750,266 or 7,573,001, the contents of which are hereby expressly incorporated herein by reference thereto. 
         [0020]    The invention has been discussed with respect to a fluid end which as shown in the drawings is known as a Y-configuration defined by the geometry of the bores. However it is evident that the same principles could be applied to a fluid end which is known in the art as having a T or C configuration. 
         [0021]    Although the present invention has been described with respect to specific details, it is not intended that such details should be regarded as limitations on the scope of the invention, except to the extent that they are included in the accompanying claims.