Patent Publication Number: US-2023141878-A1

Title: Modular suction gland assembly

Description:
FIELD 
     The present disclosure relates to hydraulic fracturing pumps, and in particular, to a modular suction gland assembly for a hydraulic fracturing pump. 
     BACKGROUND 
     Hydraulic fracturing (a.k.a. fracking) is a process to obtain hydrocarbons such as natural gas and petroleum by injecting a fracking fluid or slurry at high pressure into a wellbore to create cracks in deep rock formations. The hydraulic fracturing process employs a variety of different types of equipment at the site of the well, including one or more positive displacement pumps, slurry blender, fracturing fluid tanks, high-pressure flow iron (pipe or conduit), wellhead, valves, charge pumps, and trailers upon which some equipment are carried. 
     Positive displacement pumps are commonly used in oil fields for high pressure hydrocarbon recovery applications, such as injecting the fracking fluid down the wellbore. A positive displacement pump typically has two sections, a power end and a fluid end. The power end includes a crankshaft powered by an engine that drives the plungers. The fluid end of the pump includes cylinders into which the plungers operate to draw fluid from a suction manifold into the fluid chamber and then forcibly push out at a high pressure to a discharge manifold, which is in fluid communication with a well head. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is an elevational view of an example of a positive displacement pump that may employ modular suction gland assemblies according to the teachings of the present disclosure; 
         FIGS.  2 - 4    are perspective, side, and front views of an example embodiment of a fluid end of a positive displacement pump employing modular suction gland assemblies according to the teachings of the present disclosure; and 
         FIGS.  5  and  6    are partial cross-sectional views of example embodiments of a modular packing gland assembly for the fluid end of a positive displacement pump according to the teachings of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     The primary purpose of the suction access bore in a positive displacement pump is to provide service access to consumable components within the fluid cylinder of the pump. Conventional suction cover configurations in a positive displacement pump consists of a retainer nut that directly engages the fluid end block via a threaded connection. The retainer nut is the device that holds the suction cover in place over the suction bore access opening in the fluid end block. The suction covers are typically sealed with pressure energized seals, such as O-rings or D-ring seals. The seals prevent pressure leaks from the fluctuating pressure in the cross bores in the fluid cylinder of the pump. One of the most common reasons for failure and pressure loss is due to cyclic loading or wash rings around the sealing surfaces of the suction cover seal. In conventional pumps, such a thread failure associated with the retainer nut would mean scrapping the entire fluid end block. 
       FIG.  1    is an elevational view of a reciprocating positive displacement pump  100  that incorporates a suction cover assembly  101  described herein. The reciprocating pump  100  has two sections, a power end  104  and a fluid end  106 . The fluid end  106  of the pump  100  includes a fluid end housing  108 , which is connected to the power end housing  110  via a plurality of stay rods  112 . In operation, crankshafts (not explicitly shown) reciprocate plunger rod assemblies between the power end  104  and the fluid end  106 . The crankshafts are powered by an engine or motor (not explicitly shown) that drives plunger rod assemblies  114  to create alternating high and low pressures inside each respective pressure chamber. The cylinders operate to draw fluids from a suction manifold  116  into the pressure chambers and then discharge the fluid at a high pressure to a discharge manifold  118 . The discharged fluid is then injected at high pressure into an encased wellbore in a fracking operation. The injected fracturing fluid is also commonly called a slurry, which is a mixture of water, proppants (silica sand or ceramic), and chemical additives. The pump  100  can also be used to inject a cement mixture down the wellbore for cementing operations. The pump  100  may be freestanding on the ground, mounted to a skid, or mounted to a trailer. The suction cover assemblies  101  are used to seal off access ports to the pressure chambers within the fluid cylinders to enable access to service the inlet valve assemblies and the plunger rod assemblies  114 . Discharge cover assemblies  103  are used to seal off discharge access ports to enable access to service the outlet valve assemblies. 
     Referring to various exterior views of the fluid end  106  shown in  FIGS.  2 - 4    and partial cross-sectional views of the fluid end shown in  FIGS.  5  and  6   , the novel modular suction cover assembly solution is provided by using a suction gland  102  as the threaded connection  500  to a retainer nut  200  that serves to retain the suction cover  502  in place to close off the suction access port. Best shown in  FIG.  5   , an embodiment of the modular suction gland  102  includes a threaded inner circumferential surface that interfaces and connects with a threaded outer circumferential surface of the retainer nut  200 . The retainer nut  200  has an axial hexagonal-shaped cavity  208  that is designed to receive and interface with a hexagonal-shaped tool that can be used to rotate and tighten the retainer nut  200  within the threaded tubular cavity of the modular suction gland  102 . The retainer nut  200 , when securely engaged with the threaded interface of the modular suction gland  102 , abuts against the suction cover  502  and keeps it in place within the suction access bore. The modular suction gland  102  itself is securely fastened to the fluid end block  108  by one or more threaded fasteners  206 , such as bolts or socket head cap screws (SHCS), which are received in threaded openings formed in the modular suction gland  102  and threaded cavities formed in the fluid end block  108  spaced and arranged in an offset manner about the suction access port opening. An annular suction cover seal  504  having a suitable cross-sectional shape (e.g., circular or D) is disposed in an annular groove defined in an outer circumference of the suction cover  502  at an interface between the suction cover  502  and the modular suction gland  102 . As shown in  FIG.  5   , a face seal  510  is disposed in an annular groove formed on a face of the modular suction gland  102  to provide sealing engagement at a mating surface between the suction gland  102  and the fluid end block  108 . In an alternate embodiment of the suction gland  702  shown in  FIG.  7   , a piston seal  710  is disposed in an annular groove formed on an outer circumferential surface of the modular suction gland  702  to provide sealing engagement at a mating surface between the suction gland and the fluid end block  108 . 
     It may be seen that the modular suction gland and the retainer nut  200  project beyond the face of the fluid end block  108  and as a result, the length of threaded interface between the suction gland and retainer nut  200  may also at least partially extend beyond the face of the fluid end housing. 
     It may be seen in  FIGS.  5  and  6    that the plunger rod assembly includes a plunger  600  extending through a bore into a pressure chamber  602  defined within the fluid cylinder. The fluid cylinder includes fluid inlet and outlet passages leading from the suction manifold  116  to the discharge manifold  118 . An inlet valve assembly  608  is disposed in the fluid inlet passage  604  and an outlet valve assembly  610  is disposed in the fluid outlet passage  606 . The inlet valve assembly  608  includes a valve body  612  engaged with a valve seat  614 , and the outlet valve assembly  610  includes a valve body  616  engaged with a valve seat  618 . A generally L-shaped valve keeper  512  is disposed at the mouth of the passageway leading to the inlet valve. 
     The innovation described herein eliminates the retainer nut threads from the fluid end block  108 . Instead, the modular suction gland ( 102  or  702 ) that can be bolted to the fluid end block  108  using threaded fasteners  206 , is used to secure the suction cover  502  and retainer nut  200  within the suction access bore. The retainer nut  200  includes a threaded outside circumference that engages the threaded inside circumference of the modular suction gland, forming a threaded connection. The retainer nut  200  abuts the suction cover seal  504  disposed over the suction access bore within the fluid cylinder. The sealing ring  504  is disposed in a groove at an interface between the suction cover  502  and the modular suction gland. Configured in this way, the suction cover sealing surface and the threaded interface with the retainer nut are moved from the fluid cylinder to the modular suction gland. If this threaded interface fails, the modular suction gland and the retainer nut  200  can be more easily replaced. Further, by using the modular bolt-on gland  102 , its threaded engagement with the retainer nut  200  can be strengthened. More thread engagement is achieved by extending the modular suction gland and its threaded connection with the retainer nut  200  outward beyond the physical envelope of the fluid end block  108 . 
     The features of the present invention which are believed to be novel are set forth below with particularity in the appended claims. However, modifications, variations, and changes to the exemplary embodiments described above will be apparent to those skilled in the art, and the modular suction gland assembly for the fluid end of a reciprocating pump described herein thus encompasses such modifications, variations, and changes and are not limited to the specific embodiments described herein.