Fluid end of plunger pump and plunger pump
By eliminating the stepped structure of the valve seat and adopting inclined surface support and limiting methods, the problem of cracking in the transition zone of the valve seat was solved, and the sealing of the fracturing fluid and the durability of the valve box were achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- YANTAI JEREH PETROLEUM EQUIP & TECH CO LTD
- Filing Date
- 2025-06-06
- Publication Date
- 2026-05-08
AI Technical Summary
The transition zone of the valve seat is prone to cracking during the operation of the plunger pump, which can lead to fracturing fluid leakage and valve box damage, resulting in economic losses.
Design a hydraulic end for a plunger pump that eliminates the stepped structure of the valve seat and uses an inclined surface to cooperate with the valve box. The first inclined surface and the second inclined surface abut against each other to provide support and limit the movement, thus avoiding stress concentration.
It effectively prevents valve seat cracking, reduces fracturing fluid leakage, extends valve box life, and reduces economic losses.
Smart Images
Figure CN224214351U_ABST
Abstract
Description
Technical Field
[0001] This application belongs to the technical field of oil and gas equipment, specifically relating to a hydraulic end of a plunger pump and the plunger pump itself. Background Technology
[0002] In the development of oil and gas fields, fracturing is the main method for reservoir stimulation and production enhancement. The construction process is mainly achieved through fracturing pump equipment, which injects high-pressure, high-volume fracturing fluid into the oil and gas reservoir to break up the formation, squeeze proppant into the fractures, form artificial fractures and diversion channels, and improve oil and gas recovery rate.
[0003] The working principle of the hydraulic end is as follows: the working medium enters the alternating chamber inside the hydraulic end through the inlet, the lower valve body, and the lower valve seat. Then, under the compression of the plunger, the working medium inside the alternating chamber is compressed to a certain pressure. When the pressure reaches a certain level, it opens the upper valve body, allowing the working medium to enter the high-pressure chamber and exit from the outlet. It can be seen that during the reciprocating motion of the plunger, the alternating chamber and the components in contact with the liquid inside the alternating chamber are subjected to alternating loads.
[0004] The valve seat is a commonly used pump component in the hydraulic end assembly of oilfield plunger pumps. The main function of the valve seat is to seal and maintain the unidirectional flow of fluid. The valve seat works in conjunction with the valve body, controlling the passage of fluid through the action of fluid pressure and spring force. When the fluid flows in the forward direction, the valve seat and valve body are in an open state, allowing fluid to pass through. When the fluid flows in the reverse direction, the valve seat and valve body are in a closed state under the action of pressure and spring force, preventing fluid from passing through, thus maintaining the unidirectional flow of fluid and preventing backflow. During the operation of the plunger pump, the valve body opens and closes once for each reciprocating motion of the plunger.
[0005] In related technologies, valve seats are limited by the valve seat support surface. During operation, cracks often occur in the transition zone of the valve seat. After the transition zone of the valve seat cracks, the high-pressure working medium will leak along the crack, which will damage the valve box and cause great losses. Utility Model Content
[0006] The purpose of this application is to provide a hydraulic end of a plunger pump and a plunger pump that can solve problems such as cracking in the transition zone of the valve seat.
[0007] To solve the above-mentioned technical problems, this application is implemented as follows:
[0008] This application provides a hydraulic end of a plunger pump, the hydraulic end comprising: a valve box and a valve assembly;
[0009] The valve box is provided with a cavity and a liquid channel communicating with the cavity. The liquid channel includes a first channel section, a second channel section and a transition section. Along the flow direction of the fracturing fluid, the first channel section, the transition section and the second channel section are connected in sequence. The cross-sectional area of the first channel section is smaller than the cross-sectional area of the second channel section. The transition section is provided with a first inclined surface arranged around the circumference of the transition section.
[0010] The valve assembly includes a valve seat, and the outer wall of one end of the valve seat is provided with a second inclined surface that is arranged around the circumference of the valve seat. The valve seat is located in the second channel segment, and the second inclined surface abuts against the first inclined surface.
[0011] This application also provides a plunger pump, including the hydraulic end described above.
[0012] In this embodiment, the valve seat and the valve box are engaged through the contact of the first inclined surface and the second inclined surface. Compared with the related technology, which sets a stepped structure on the outer wall of the valve seat to support the stepped structure through the valve box, the transition zone structure formed by the step support is eliminated. This can effectively alleviate the problem of stress concentration in the transition area of the valve seat step, which leads to cracking. It can also effectively prevent the fracturing fluid from leaking along the crack and damaging the valve box after the valve seat cracks. Attached Figure Description
[0013] Figure 1 This is a cross-sectional schematic diagram of the hydraulic end disclosed in the embodiments of this application;
[0014] Figure 2 This is a partial schematic diagram of the valve component disclosed in the embodiments of this application;
[0015] Figure 3 This is a partial schematic diagram of the valve box disclosed in an embodiment of this application;
[0016] Figure 4 This is a schematic diagram of the valve seat disclosed in the embodiments of this application;
[0017] Figure 5 This is a first schematic diagram of the assembly of the valve component and valve box disclosed in the embodiments of this application;
[0018] Figure 6 This is a second schematic diagram of the assembly of the valve component and valve box disclosed in the embodiments of this application.
[0019] Explanation of reference numerals in the attached figures:
[0020] 10-Valve box;
[0021] 11-Cavity; 12-Liquid Channel; 12a-Inlet Channel; 12b-Outlet Channel; 121-First Channel Section; 122-Transition Section; 1221-First Inclined Surface; 123-Second Channel Section;
[0022] 20 - Valve assembly; 21 - Valve seat; 211 - Second inclined surface; 212 - Groove; 22 - Valve body;
[0023] 30 - Sealing ring;
[0024] 40-plunger;
[0025] 50-packing assembly. Detailed Implementation
[0026] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.
[0027] The terms "first," "second," etc., used in the specification and claims of this application are used to distinguish similar objects and not to describe a specific order or sequence. It should be understood that such use of data can be interchanged where appropriate so that embodiments of this application can be implemented in orders other than those illustrated or described herein, and the objects distinguished by "first," "second," etc., are generally of the same class and the number of objects is not limited; for example, a first object can be one or more. Furthermore, in the specification and claims, "and / or" indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.
[0028] The embodiments of this application will be described in detail below with reference to the accompanying drawings and specific examples and application scenarios.
[0029] refer to Figures 1 to 6 This application discloses a hydraulic end of a plunger pump, which includes a valve box 10 and a valve assembly 20.
[0030] Valve box 10 is provided with cavity 11 and liquid channel 12 communicating with cavity 11. Optionally, liquid channel 12 may include inlet channel 12a and outlet channel 12b. Fracturing fluid can enter cavity 11 through inlet channel 12a to facilitate subsequent pressurization of fracturing fluid. Pressurized fracturing fluid can be discharged out of valve box 10 through outlet channel 12b to facilitate downstream delivery of pressurized fracturing fluid.
[0031] The valve assembly 20 may include a valve seat 21 disposed in the liquid channel 12. Optionally, the valve seat 21 may be disposed in the inlet channel 12a and the outlet channel 12b respectively. Additionally, the valve assembly 20 may also include a valve body 22 disposed in the valve seat 21 and movable relative to the valve seat 21 to facilitate opening or closing. Besides this, the valve assembly 20 may also include other components, such as springs, pressure caps, etc., as detailed in related technologies.
[0032] Optionally, the valve assembly 20 can be divided into an upper valve assembly 20 and a lower valve assembly 20, which are respectively installed in the valve box 10 to control the inflow or outflow of fracturing fluid into the valve box 10. In addition, the hydraulic end may also include a plunger 40, a packing assembly 50, etc. The reciprocating motion of the plunger 40 realizes the compression of fracturing fluid, and the packing assembly 50 realizes the sealing between the plunger 40 and the valve box 10.
[0033] The working principle of the hydraulic end is as follows: the working medium enters the valve box 10 through the lower valve assembly. Under the pushing and compressing action of the plunger 40, the fracturing fluid entering the valve box 10 is compressed to a certain pressure, which opens the upper valve assembly, allowing the fracturing fluid to be discharged outside the valve box 10. Therefore, during the reciprocating motion of the plunger 40, the fracturing fluid exerts alternating loads on the components inside the valve box 10.
[0034] The main function of valve seat 21 is to seal and maintain the unidirectional flow of fracturing fluid. The cooperation between valve seat 21 and valve body 22, through the pressure of the fracturing fluid and the force of the spring, controls whether the fracturing fluid passes through. Specifically, when the fracturing fluid flows in the forward direction, valve seat 21 and valve body 22 are in an open state, allowing the fracturing fluid to flow through; when the fracturing fluid flows in the reverse direction, valve seat 21 and valve body 22 are closed under the pressure of the fracturing fluid and the force of the spring, preventing the fracturing fluid from flowing through, thus ensuring the unidirectional flow of the fracturing fluid and preventing backflow. During the operation of the plunger pump, valve body 22 opens and closes once for each reciprocating motion of the plunger 40.
[0035] In related technologies, the outer wall of the valve seat 21 has a stepped structure, at least a portion of which is embedded into the liquid flow channel. The stepped structure is supported and limited by a support structure within the liquid flow channel. However, during fracturing operations, the transition zone at the stepped structure of the valve seat 21 often cracks under load. After the transition zone of the valve seat 21 cracks, the fracturing fluid leaks along the crack, damaging the valve box 10 and causing serious economic losses.
[0036] The economic losses caused by cracking in the transition zone of valve seat 21 are significant, and further solutions are needed. To address the cracking problem in the transition zone of valve seat 21, this application redesigns the structure of valve box 10 and valve seat 21, changing the method of valve seat 21 and valve box 10 engaging via a stepped structure as in related technologies.
[0037] Among them, such as Figure 3 As shown, the hydraulic channel of the valve box 10 may include a first channel section 121, a second channel section 123 and a transition section 122. Along the flow direction of the fracturing fluid, the first channel section 121, the transition section 122 and the second channel section 123 are connected in sequence so that the fracturing fluid can flow along the first channel section 121, the transition section 122 and the second channel section 123.
[0038] Furthermore, the cross-sectional area within the first channel segment 121 is greater than or less than the cross-sectional area within the second channel segment 123, so that the valve seat 21 can be located in the second channel segment 123 to facilitate support and limitation of the valve seat 21.
[0039] Considering that when the stepped structure of valve seat 21 is removed, although no transition zone is formed on the outer wall of valve seat 21, a stepped structure needs to be formed in the liquid channel 12 of valve box 10 to support and limit valve seat 21, thus forming a transition zone at the stepped structure, which is a stress concentration area. When the hydraulic end is working, the fracturing fluid will transmit pressure to the stepped structure of valve box 10 through valve body 22 and valve seat 21. Moreover, this force changes periodically with the opening and closing of valve body 22. Over time, cracks will appear in the transition zone, and the cracks are prone to rapid propagation, eventually leading to the scrapping of valve box 10.
[0040] Based on the above situation, such as Figure 3 and Figure 4 As shown, the transition section 122 may be provided with a first inclined surface 1221 that is arranged around the circumference of the transition section 122. Correspondingly, the outer wall of one end of the valve seat 21 may be provided with a second inclined surface 211 that is arranged around the circumference of the valve seat 21, and the second inclined surface 211 abuts against the first inclined surface 1221.
[0041] Optionally, both the first inclined surface 1221 and the second inclined surface 211 can be conical surfaces. In some more specific embodiments, both the first inclined surface 1221 and the second inclined surface 211 can be conical surfaces. Of course, other conical surfaces can also be used, which are not specifically limited here.
[0042] This embodiment of the application can achieve the supporting and limiting function of the valve seat 21 by the cooperation of the first inclined surface 1221 and the second inclined surface 211. Compared with the related technology, which sets a stepped structure on the outer wall of the valve seat 21 to support the stepped structure through the valve box 10, the transition zone structure formed by the stepped support is eliminated. This can effectively alleviate the problem of stress concentration in the transition area of the stepped valve seat 21 and cracking, and effectively prevent the fracturing fluid from leaking along the crack and damaging the valve box 10 after the valve seat 21 cracks.
[0043] Compared to setting a stepped structure in the liquid channel 12 of the valve box 10, setting a first inclined surface 1221 can effectively alleviate the problem of stress concentration inside the valve box 10 and effectively prevent the valve box 10 from being scrapped due to cracks inside the valve box 10.
[0044] refer to Figure 3 In some embodiments, a first angle θ may be formed between the inclined extension direction of the first inclined surface 1221 and the axial direction of the liquid channel 12. Correspondingly, a second angle may be formed between the inclined extension direction of the second inclined surface 211 and the axial direction of the valve seat 21. The first angle θ and the second angle are equal, so as to increase the contact area, improve the tightness of the fit, and ensure the sealing performance.
[0045] By forming the first included angle θ and the second included angle, the stress concentration problem in the transition section 122 and the stress concentration problem at one end of the valve seat 21 can be alleviated.
[0046] Considering that the cross-sectional area within the second channel section 123 is limited by the suction or discharge orifice diameter of the valve box 10, in principle, the smaller the suction or discharge orifice diameter, the better, as this can reduce the stress on the threads of the suction or discharge cap. Furthermore, the cross-sectional area within the first channel section 121 is a standard industry size, and this size is compatible with the disassembly tools for the valve seat 21. Changing this size would not only affect disassembly but also the flow rate of the fracturing fluid.
[0047] In addition, the function of the first inclined surface 1221 of the transition section 122 is to support the valve seat 21 so that the valve seat 21 will not have a large displacement under pressure. The magnitude of the displacement of the valve seat 21 determines the support of the first inclined surface 1221 for the valve seat 21. Furthermore, it is also necessary to minimize the stress at the first inclined surface 1221 as much as possible so that cracks are not easily generated at the transition section 122.
[0048] Based on the above, this application embodiment has conducted an in-depth study on the first included angle θ, and performed simulation calculations at the first included angle θ of 20°, 30°, 45°, 60°, 70°, 80° and 90° respectively, in order to obtain the optimal range of the first included angle θ.
[0049] The stress at transition section 122 was obtained under the above different angle values, as shown in Table 1.
[0050]
[0051] The displacement of the valve seat 21 under the above different angle values is shown in Table 2.
[0052]
[0053] Based on the simulation results above, it can be seen that as the angle value increases, the stress at the transition section 122 increases, but the displacement of the valve seat 21 decreases, indicating that the support of the first inclined surface 1221 for the valve seat 21 improves. Research has shown that the range of the first included angle θ is 25° to 70°, including, for example, 25°, 30°, 35°, 40°, 45°, 50°, 55°, 60°, 65°, 70°, etc. Of course, other degrees are also possible, and no specific limitation is made here.
[0054] Accordingly, the angle range of the second included angle can also be 25° to 70°, such as 25°, 30°, 35°, 40°, 45°, 50°, 55°, 60°, 65°, 70°, etc. Of course, it can also be other degrees, which are not specifically limited here.
[0055] Based on the angle ranges of the first included angle θ and the second included angle, it is beneficial to alleviate the stress concentration problem at the end of the transition section 122 and the valve seat 21, so as to prevent cracks from forming.
[0056] refer to Figure 1 , Figure 2 and Figure 4 In some embodiments, the second inclined surface 211 is connected to the end face of one end of the valve seat 21, and at least a portion of the second inclined surface 211 extends to the first channel segment 121, with the end face of one end of the valve seat 21 opposite to the first channel segment 121. Based on this arrangement, the second inclined surface 211 can completely cover the first inclined surface 1221, preventing fracturing fluid from directly scouring the first inclined surface 1221 and effectively preventing erosion of the first inclined surface 1221.
[0057] It should be noted that the valve seat 21 is provided with a through hole, and the valve body 22 is movably disposed in the through hole; the second inclined surface 211 extends inclinedly from the outer wall of the valve seat 21 toward the axis of the valve seat 21. However, the end of the second inclined surface 211 is not directly connected to the wall of the through hole, but the end of the second inclined surface 211 is connected to the end face of the valve seat 21, and the wall of the through hole is also connected to the end face of the valve seat 21, so as to improve the strength at the end of the through hole and prevent the valve body 22 from squeezing the valve seat 21 and causing the valve seat 21 to deform.
[0058] refer to Figure 1 In some embodiments, the liquid channel 12 may include an inlet channel 12a and an outlet channel 12b, and the inlet channel 12a and the outlet channel 12b are respectively connected to the cavity 11 so as to introduce fracturing fluid into the cavity 11 through the inlet channel 12a and discharge the fracturing fluid in the cavity 11 through the outlet channel 12b.
[0059] In the inlet channel 12a, the first channel section 121 is located away from the cavity 11, and the second channel section 123 is located close to the cavity 11. In this way, the fracturing fluid can pass through the first channel section 121 and the valve seat 21 located in the second channel section 123 in sequence and enter the cavity 11 of the valve box 10 to realize the inflow of fracturing fluid.
[0060] In the outlet channel 12b, the first channel section 121 is located close to the cavity 11, and the second channel section 123 is located away from the cavity 11. In this way, the pressurized fracturing fluid can be discharged from the cavity 11 through the first channel section 121 and the valve seat 21 located in the second channel section 123 to the outside of the valve box 10, so as to realize the discharge of fracturing fluid.
[0061] In some embodiments, the first inclined surface 1221 abuts against the second inclined surface 211, thereby ensuring the stable support provided by the first inclined surface 1221 to the second inclined surface 211 and guaranteeing the installation stability of the valve seat 21. Furthermore, this abutment also helps improve the sealing between the first inclined surface 1221 and the second inclined surface 211, preventing fracturing fluid leakage between them.
[0062] In addition, the outer wall of the valve seat 21 and the inner wall of the second channel section 123 can be interference-fitted. This can ensure the installation stability of the valve seat 21 and improve the sealing between the outer wall of the valve seat 21 and the inner wall of the second channel section 123, so as to prevent the fracturing fluid from leaking from the outer wall of the valve seat 21 and the inner wall of the second channel section 123.
[0063] To further improve the sealing between the outer wall of the valve seat 21 and the inner wall of the second channel section 123, the hydraulic end may also include a sealing ring 30, such as... Figure 1 , Figure 2 , Figure 5 and Figure 6 As shown, the sealing ring 30 is disposed between the outer wall of the valve seat 21 and the inner wall of the second channel section 123, so that a good seal can be formed between the outer wall of the valve seat 21 and the inner wall of the second channel section 123 to prevent fracturing fluid leakage.
[0064] In this design, at least one of the outer wall of the valve seat 21 and the inner wall of the second channel section 123 may be provided with a groove 212, and the sealing ring 30 is disposed in the groove 212. This increases the contact area between the sealing ring 30 and at least one of the outer wall of the valve seat 21 and the inner wall of the second channel section 123, which is beneficial to improving the sealing performance. In addition, the side wall of the groove 212 can limit the sealing ring 30 to prevent the sealing ring 30 from moving at will.
[0065] Considering that the fracturing fluid contains fracturing sand and that the fracturing sand flows at a relatively high velocity, to prevent the fracturing fluid from eroding the valve box, in this embodiment of the application, the end face of the valve seat 21 opposite to the second inclined surface 211 is flush with the port of the second channel section 123, or the end face of the valve seat 21 opposite to the second inclined surface 211 protrudes beyond the port of the second channel section 123. Based on this arrangement, the fracturing fluid can effectively prevent erosion of the valve box body, thereby alleviating the problem of stress concentration at the erosion location, ensuring that cracks are not easily generated at the erosion location, and extending the service life of the valve box.
[0066] Of course, in other embodiments, the port of the second channel segment 123 may protrude from the end face of the valve seat 21 opposite to the second inclined surface 211.
[0067] All three implementation methods described above can meet actual needs, and the specific method can be selected based on the actual working conditions.
[0068] In some embodiments, the valve seat 21 may be made of steel. Optionally, the valve seat 21 may be made of alloy steel, carbon steel, or stainless steel, and of course, other types of steel may also be used, without specific limitations.
[0069] In other embodiments, the material of the valve seat 21 can also be a metallic wear-resistant material or a non-metallic wear-resistant material. Optionally, the material of the valve seat 21 may include zirconium oxide, nickel-based tungsten carbide, cobalt-based tungsten carbide, titanium carbide, boron nitride, or ceramic. Of course, other wear-resistant materials may also be used, which are not specifically limited here.
[0070] Based on the aforementioned hydraulic end, this application also discloses a plunger pump, which includes the aforementioned hydraulic end.
[0071] In summary, the embodiments of this application eliminate the stepped structure of the valve seat 21, and change the contact limiting position between the valve seat 21 and the valve box 10 from the original stepped structure to an inclined surface limiting position. Furthermore, eliminating the stepped structure of the valve seat 21 can also change the stress position, so fatigue cracks will not occur even if the valve body is repeatedly opened and closed. In addition, since there is an interference fit between the valve seat 21 and the valve box 10, and there is no stepped structure, the valve seat 21 will not deform inward due to stress, and the contact surface with the valve body will not slip. The contact surface will not wear in a short period of time, thus improving the service life of the valve seat 21.
[0072] The embodiments of this application have been described above with reference to the accompanying drawings. However, this application is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of this application without departing from the spirit and scope of the claims, and all of these forms are within the protection scope of this application.
Claims
1. A hydraulic end of a plunger pump, characterized in that, The hydraulic end includes: a valve box (10) and a valve assembly (20); The valve box (10) is provided with a cavity (11) and a liquid channel (12) communicating with the cavity (11). The liquid channel (12) includes a first channel section (121), a second channel section (123) and a transition section (122). Along the flow direction of the fracturing fluid, the first channel section (121), the transition section (122) and the second channel section (123) are connected in sequence. The cross-sectional area of the first channel section (121) is smaller than the cross-sectional area of the second channel section (123). The transition section (122) is provided with a first inclined surface (1221) arranged around the circumference of the transition section (122). The valve assembly (20) includes a valve seat (21), and the outer wall of one end of the valve seat (21) is provided with a second inclined surface (211) arranged around the circumference of the valve seat (21). The valve seat (21) is located in the second channel segment (123), and the second inclined surface (211) abuts against the first inclined surface (1221).
2. The hydraulic end according to claim 1, characterized in that, The angle between the inclined extension direction of the first inclined surface (1221) and the axial direction of the liquid channel (12) ranges from 25° to 70°.
3. The hydraulic end according to claim 1, characterized in that, The second inclined surface (211) is connected to the end face of one end of the valve seat (21); At least a portion of the second inclined surface (211) extends to the first channel segment (121), and the end face of one end of the valve seat (21) is disposed opposite to the first channel segment (121).
4. The hydraulic end according to any one of claims 1 to 3, characterized in that, Both the first inclined surface (1221) and the second inclined surface (211) are conical surfaces.
5. The hydraulic end according to any one of claims 1 to 3, characterized in that, The liquid channel (12) includes an inlet channel (12a) and an outlet channel (12b). In the liquid inlet channel (12a), the first channel segment (121) is disposed away from the cavity (11), and the second channel segment (123) is disposed close to the cavity (11); In the liquid outlet channel (12b), the first channel segment (121) is located close to the cavity (11), and the second channel segment (123) is located away from the cavity (11).
6. The hydraulic end according to claim 1, characterized in that, The first inclined surface (1221) abuts against the second inclined surface (211); And / or, the outer wall of the valve seat (21) is interference-fitted with the inner wall of the second channel segment (123).
7. The hydraulic end according to claim 1 or 6, characterized in that, At least one of the outer wall of the valve seat (21) and the inner wall of the second channel segment (123) is provided with a groove (212). The hydraulic end also includes a sealing ring (30), which is disposed in the groove (212).
8. The hydraulic end according to claim 1, characterized in that, The end face of the valve seat (21) opposite to the second inclined surface (211) is flush with the port of the second channel segment (123); Alternatively, the end face of the valve seat (21) opposite to the second inclined surface (211) protrudes from the port of the second channel segment (123); Alternatively, the port of the second channel segment (123) protrudes from the end face of the valve seat (21) opposite to the other end of the second inclined surface (211).
9. The hydraulic end according to claim 1, characterized in that, The material of the valve seat (21) is metal steel, including alloy steel, carbon steel or stainless steel; Alternatively, the material of the valve seat (21) may be a metal wear-resistant material or a non-metal wear-resistant material, including zirconium oxide, nickel-based tungsten carbide, cobalt-based tungsten carbide, titanium carbide, boron nitride or ceramic.
10. A plunger pump, characterized in that, Includes the hydraulic end as described in any one of claims 1 to 9.