阅读说明：本技术 用于流体端应用的阀座和阀组件 (Valve seat and valve assembly for fluid end applications ) 是由 C.巴特科瓦克 J.布罗斯纳安 M.凯利 R.斯塔克 于 2019-07-17 设计创作，主要内容包括：本发明题为“用于流体端应用的阀座和阀组件”。在一个方面,本文描述了阀座,所述阀座的结构和设计解决了阀座在流体端中进行安装和操作期间遇到的退化应力。在一些实施方案中,用于流体端的阀座包括用于插入流体端的流体通道中的第一节段以及从第一节段纵向延伸的第二节段,该第二节段包括截头圆锥形阀配合表面,其中第二节段被包围在将压缩应力条件赋予第二节段的环中。(The invention is entitled "valve seat and valve assembly for fluid end applications". In one aspect, valve seats are described herein whose structure and design addresses the degenerative stresses encountered during installation and operation of the valve seats in a fluid end. In some embodiments, a valve seat for a fluid end includes a first segment for insertion into a fluid passage of the fluid end and a second segment extending longitudinally from the first segment, the second segment including a frustoconical valve mating surface, wherein the second segment is enclosed in a ring that imparts a compressive stress condition to the second segment.)

1. A valve seat for a fluid end, the valve seat comprising:

a body comprising a first segment for insertion into a fluid channel of the fluid end and a second segment extending longitudinally from the first segment, the second segment comprising a recess in which a cemented hard carbide insert is positioned, wherein the cemented hard carbide insert comprises a valve mating surface and exhibits a compressive stress condition.

2. The valve seat of claim 1 wherein the surface roughness (R) of the valve mating surface of the cemented carbide insert _a) Is 1-15 μm.

3. The valve seat of claim 1 wherein said valve mating surface of said cemented carbide insert is frustoconical.

4. The valve seat of claim 1 wherein said second segment imparts said compressive stress condition to said cemented carbide insert.

5. The valve seat of claim 4 wherein the inner annular surface of the second segment includes one or more protrusions for engaging the cemented carbide insert.

6. The valve seat of claim 1, wherein the body is formed from a metal or alloy.

7. The valve seat of claim 1, wherein an outer diameter of the first segment is equal to an outer diameter of the second segment.

8. The valve seat of claim 1, wherein the outer diameters of the first segment and the second segment are not equal.

9. The valve seat of claim 8, wherein the outer diameter of the second segment is greater than the outer diameter of the first segment.

10. The valve seat of claim 1 wherein said compressive stress condition of said cemented carbide insert is at least 0.5 GPa.

11. The valve seat of claim 1 wherein said compressive stress condition of said cemented carbide insert is 1-2.5 GPa.

12. A fluid end, the fluid end comprising:

a suction fluid channel and a discharge fluid channel; and

a valve assembly in at least one of the suction fluid channel and the discharge fluid channel, the valve assembly comprising a valve in reciprocal contact with a valve seat, the valve seat comprising a body including a first segment for insertion into the suction fluid channel or the discharge fluid channel and a second segment extending longitudinally from the first segment, the second segment including a recess in which a cemented hard carbide insert is positioned, wherein the cemented hard carbide insert comprises a valve mating surface and exhibits a compressive stress condition.

13. A fluid end according to claim 12 wherein the compressive stress condition of the cemented carbide insert is substantially equal to a compressive stress condition of the first segment.

14. The fluid end of claim 12 wherein the surface roughness (R) of the valve mating surface of the cemented carbide insert _a) Is 1-15 μm.

15. The fluid end of claim 12 wherein the body is formed of a metal or alloy.

16. The fluid end of claim 12 wherein an outer diameter of the first segment is equal to an outer diameter of the second segment.

17. The fluid end of claim 12 wherein the outer diameters of the first segment and the second segment are not equal.

18. The fluid end of claim 17 wherein the outer diameter of the second segment is greater than the outer diameter of the first segment.

19. The fluid end of claim 12 wherein the compressive stress condition of the cemented carbide insert is at least 0.5 GPa.

20. The fluid end of claim 12 wherein the compressive stress condition of the cemented carbide insert is at least 1-2.5 GPa.

Technical Field

The present invention relates to valve seats and valve assemblies for fluid end applications, and in particular to valve seats comprising cemented carbide components.

Background

Valves and associated valve assemblies play a critical role in the fluid end of high pressure pumps that contain positive displacement pistons in multiple cylinders. The operating environment of the valve is often harsh due to high pressures and periodic impacts between the valve body and the valve seat. These severe operating conditions can cause premature failure and/or leakage of the valve assembly. Further, the fluid passing through the fluid end and contacting the valve assembly may include high levels of particulate matter from the hydraulic fracturing operation. In hydraulic fracturing, a particulate slurry is employed to maintain fracture openings in a geological formation after the water pressure from a well is released. In some embodiments, alumina particles are employed in the slurry because of their higher compressive strength relative to silica particles or sand. The particulate slurry can impart significant wear on the contacting surfaces of the valve and valve seat. In addition, slurry particles can become trapped in the valve sealing cycle, causing further performance degradation of the valve assembly.

In view of these problems, valve seats have been made from a variety of hard and wear resistant materials, including hard carbides. Although carbide valve seats exhibit high hardness and wear resistance, they may occasionally fail catastrophically due to stresses in the carbide caused by installation and removal forces, application loads, and press-fit with the fluid end.

Disclosure of Invention

In one aspect, valve seats are described herein whose structure and design addresses the degenerative stresses encountered during installation and operation of the valve seats in a fluid end. In some embodiments, a valve seat for a fluid end includes a first segment for insertion into a fluid passage of the fluid end and a second segment extending longitudinally from the first segment, the second segment including a frustoconical valve mating surface, wherein the second segment is enclosed in a ring that imparts a compressive stress condition to the second segment. In some embodiments, the second segment is at least partially formed of cemented hard carbide. In some embodiments, the outer diameter of the second section is greater than the outer diameter of the first section. In other embodiments, the outer diameters of the first and second segments are equal or substantially equal.

In another aspect, a valve seat includes a first segment for insertion into a fluid passage of a fluid end and a second segment extending longitudinally from the first segment, the second segment including a surface roughness (R) _a) A frustoconical valve mating surface of cemented hard carbide of 1-15 μm. In some embodiments, cemented carbide of the valve mating surface is provided as a mosaic ring coupled to a metal or alloy body. In other embodiments, the second segment is formed of cemented hard carbide. The outer diameter of the second section may be greater than the outer diameter of the first section. Alternatively, the outer diameters of the first and second segments are equal or substantially equal.

In another aspect, a valve seat for a fluid end includes a body including a first segment for insertion into a fluid passage of the fluid end and a second segment extending longitudinally from the first segment. The second segment includes a recess in which a cemented hard carbide insert is positioned, wherein the cemented hard carbide insert includes a valve mating surface and exhibits a compressive stress condition.

In another aspect, a valve assembly for a fluid end is provided. The valve assembly includes a valve in reciprocating contact with a valve seat including a first section for insertion into a fluid passage of the fluid end and a second section extending longitudinally from the first section, the second section having a frustoconical valve mating surface. In some embodiments, the outer diameter of the second section is greater than the outer diameter of the first section. Alternatively, the outer diameters of the first and second segments may be equal or substantially equal. The second segment may also be enclosed in a ring that imparts a compressive stress condition to the second segment. In some embodiments, the second segment is optionally enclosed in a ring, and the valve mating surface comprises a surface roughness (R |) _a) 1-15 μm cemented hard carbide. In other embodiments, the frustoconical valve mating surface of the second segment is configured as a cemented carbide insert coupled to the metal or alloy body. In some embodiments, the metal or alloy body may impart a compressive stress condition to the cemented carbide insert. For example, the metal or alloy body may be part of the second section and willThe compressive stress condition is imparted solely to the cemented hard carbide insert and/or may transmit the compressive stress imparted by the ring surrounding the second segment. Additionally, the surface roughness (R) of cemented carbide inserts _a) Can be 1-15 μm.

In another aspect, a fluid end is described. The fluid end includes a suction fluid passage and a discharge fluid passage. A valve assembly is positioned in at least one of the suction fluid passage and the discharge fluid passage, the valve assembly including a valve in reciprocating contact with a valve seat. The valve seat includes a first segment for insertion into the suction or discharge fluid passageway and a second segment extending longitudinally from the first segment. The second section includes a frustoconical valve mating surface and is enclosed in a ring that imparts a compressive stress condition to the second section. In some embodiments, the second segment is optionally enclosed in a ring, and the valve mating surface comprises a surface roughness (R |) _a) 1-15 μm cemented hard carbide. In other embodiments, the frustoconical valve mating surface of the second segment is configured as a cemented carbide insert coupled to the metal or alloy body, wherein the cemented carbide has a surface roughness (R) _a) Is 1-15 μm. In such embodiments, the metal or alloy body may impart a compressive stress condition to the cemented carbide insert. Further, the outer diameter of the second section may be greater than the outer diameter of the first section. In other embodiments, the outer diameters of the first and second segments are equal or substantially equal.

These and other embodiments are further described in the following detailed description.

Drawings

Fig. 1 is a cross-sectional schematic view of a valve seat according to some embodiments.

Fig. 2 is a cross-sectional schematic view of a valve seat according to some embodiments.

Fig. 3 is a bottom plan view of a valve seat according to some embodiments.

Fig. 4 is a top plan view of a valve seat according to some embodiments.

Fig. 5 is a perspective view of a valve seat according to some embodiments.

Fig. 6 is a side elevational view of a valve seat according to some embodiments.

Fig. 7 is a cross-sectional view of a cemented hard carbide insert according to some embodiments.

FIG. 8 is a cross-sectional view of a valve seat including a cemented carbide insert coupled to an alloy body or shell according to some embodiments.

Detailed Description

The embodiments described herein may be understood more readily by reference to the following detailed description and examples and the foregoing and following. However, the elements, devices, and methods described herein are not limited to the specific embodiments presented in the detailed description and examples. It should be recognized that these embodiments are merely illustrative of the principles of the present invention. Various modifications and alterations will become apparent to those skilled in the art without departing from the spirit and scope of the invention.

In one aspect, a valve seat for fluid end applications is described herein. In some embodiments, the valve seat may mitigate severe operating conditions for hydraulic fracturing applications, thereby enhancing life and reducing sudden valve seat failure. Referring now to fig. 1, a valve seat 10 includes a first segment 11 for insertion into a fluid passageway of a fluid end. In the embodiment of fig. 1, the first segment 11 includes a tapered outer surface 12 and an inner surface 13 that is generally parallel to a longitudinal axis 14 of the valve seat 10. In some embodiments, the inner surface 13 may also be tapered. The tapered outer surface 12 may exhibit a variable outer diameter D1 of the first segment 11. Alternatively, the outer surface 12 of the first segment 11 is not tapered and remains parallel to the longitudinal axis 14. In such embodiments, the first segment 11 has a static outer diameter D1. The outer surface 12 of the first segment may further comprise one or more recesses 15 for receiving O-rings. One or more O-rings may help seal with the walls of the fluidic channel.

The second segment 16 extends longitudinally from the first segment 11. The outer diameter D2 of the second segment is greater than the outer diameter D1 of the first segment 11. In the embodiment of fig. 1, the ring 19 surrounding the second segment 16 forms a portion of the outer diameter D2. In some embodiments, the ring 19 may allow for the second segment 16 to have a larger outer diameter than the first segment 11. In such embodiments, the body of the valve seat may be cylindrical, with the addition of the ring 19 providing the second segment 16 with a larger outer diameter D2. Alternatively, as shown in fig. 1 and 2, the outer diameter D2 of the second segment 16, independent of the ring 19, may be greater than the outer diameter D1 of the first segment.

Shoulder 17 is formed by the larger outer diameter D2 of second segment 16. In the embodiment of fig. 1, the shoulder surface 17a is substantially perpendicular to the longitudinal axis 14 of the valve seat 10. In other embodiments, the shoulder surface 17a may taper and/or form an angle with the longitudinal axis that is between 5 and 70 degrees. The design of the shoulder 17 may be selected based on a number of considerations, including but not limited to the inlet geometry of the fluid passageway and the pressure experienced by the valve seat in operation. In some embodiments, for example, the taper of the shoulder may be set according to the curvature of the fluid passage inlet that engages the shoulder. The first segment 11 transitions to the second segment 16 at a curved intersection 18. The curved intersection may have any desired radius. In some embodiments, the radius at the curved intersection may be 0.05 to 0.5 times the width of the shoulder. In other embodiments, there is no curved transition between the first segment and the second segment. Further, in some embodiments, the outer diameter (D2) of the second segment (16) is equal or substantially equal to the outer diameter (D1) of the first segment (11) (e.g., D1 ═ D2).

The second section 16 further comprises a frusto-conical valve mating surface 20, wherein the second section 16 is surrounded by a ring 19. In the embodiment of fig. 1, the ring 19 is coupled to the outer surface of the second segment 16 in a concentric arrangement. The ring 19 imparts a compressive stress condition to the second segment 16. By placing the second segment 16 in compressive stress, the ring 19 may help balance or equalize stress between the first segment 11 and the second segment 16 when the first segment 11 is press-fit into a fluid channel of a fluid end. The compressive stress condition may also inhibit crack formation and/or propagation in the second segment 16, thereby enhancing the life of the valve seat and reducing the occurrence of sudden or catastrophic valve seat failures. The compressive stress condition may also enable the use of harder and more brittle materials in the second segment 16, such as harder and more wear resistant grades of hard carbide that form the valve mating surface.

In the embodiment of fig. 1, the ring 19 forms a planar interface with the outer surface or perimeter of the second segment 16. In other embodiments, the ring 19 may include one or more protrusions or flanges that reside on the inner annular surface of the ring 19. A protrusion or flange on the inner ring surface may fit into a recess or groove along the perimeter of the second segment 16. This structural arrangement may facilitate proper engagement between the ring 19 and the second segment 16. This structural arrangement may also help to retain the second segment 16 within the ring 19 during operation of the fluid end. In another embodiment, the second segment 16 may include one or more flanged protrusions for engaging one or more recesses in the inner annular surface of the ring 19.

FIG. 2 is a schematic view illustrating another embodiment of a valve seat described herein. The valve seat of fig. 2 includes the same structural features shown in fig. 1. But the ring 19 in figure 2 at least partially covers the shoulder 17. For example, the ring 19 may be provided with a radial flange 19a for connecting the shoulder 17 of the second segment 16. In some embodiments, the ring 19 completely covers the shoulder 17. FIG. 3 is a perspective view of a valve seat having the architecture of FIG. 2. As shown in fig. 3, a ring 19 is coupled to the periphery of the second segment and partially covers the shoulder 17. FIG. 4 is another perspective view of a valve seat having the architecture of FIG. 2. The frusto-conical valve mating surface 20 transitions into the bore 21 of the valve seat 10. The ring 19 surrounds the second segment 16, thereby imparting a compressive stress condition to the second segment 16. Accordingly, a compressive stress condition is imparted to the valve mating surface 20, which may help resist crack formation and/or crack propagation in the mating surface 20. Fig. 3 and 4 show bottom and top plan views, respectively, of the valve seat of fig. 2. Furthermore, fig. 5 shows a perspective view of the valve seat of fig. 2. Fig. 6 illustrates a side elevation view of a valve seat according to some embodiments, wherein there is no curved intersection between the first segment 11 and the second segment 16.

As described herein, the valve seat may comprise cemented hard carbide. In some embodiments, the first and second sections of the valve seat are each formed of cemented hard carbide. Alternatively, the first segment may be formed of a metal or alloy (such as steel or a cobalt-based alloy) and the second segment is formed of cemented hard carbide. Forming the second segment of cemented hard carbide may impart hardness and wear resistance to the valve mating surface relative to other materials, such as steel.

In some embodiments, the second segment is formed from a composite material comprising cemented carbide and an alloy. For example, a cemented hard carbide insert may be coupled to a steel substrate, wherein the cemented hard carbide insert forms a portion or all of the valve mating surface and the steel substrate forms the remainder of the second segment. In such embodiments, the cemented carbide insert may extend radially to contact the ring surrounding the second segment, thereby allowing the ring to impart a compressive stress condition to the cemented carbide insert. In other embodiments, the steel or alloy substrate includes a recess in which the cemented carbide insert is positioned. In this embodiment, the outer edge of the recess is positioned between the cemented carbide insert and the ring, wherein the compressive stress imparted by the ring is transferred to the cemented carbide insert through the outer edge.

The cemented hard carbide of the valve seat may comprise tungsten carbide (WC). WC may be present in the cemented carbide in an amount of at least 70 wt.% or in an amount of at least 80 wt.%. Additionally, the metallic binder of the hard carbide may comprise cobalt or a cobalt alloy. For example, cobalt may be present in the cemented hard carbide in an amount in the range of 3 wt.% to 20 wt.%. In some embodiments, the cobalt is present in the cemented hard carbide of the valve seat in an amount in the range of 5-12 wt.%, or 6-10 wt.%. In addition, the cemented carbide valve seat may have a binder-rich region that originates at and extends inward from the substrate surface. The cemented hard carbide of the valve seat may also contain one or more additives such as, for example, one or more of the following elements and/or compounds thereof: titanium, niobium, vanadium, tantalum, chromium, zirconium and/or hafnium. In some embodiments, titanium, niobium, vanadium, tantalum, chromium, zirconium, and/or hafnium forms solid solution carbides with WC of the cemented hard carbide. In such embodiments, the cemented carbide may comprise one or more solid solution carbides in an amount in the range of 0.1 to 5 weight percent.

In some embodiments, a single grade of cemented hard carbide may be used to form the first and second sections of the valve seat. In other embodiments, there may be one or more compositional gradients between the cemented hard carbides of the first and second segments. For example, the cemented hard carbide of the first segment may have a larger average grain size and/or a higher metallic binder content to increase toughness. In contrast, the cemented hard carbides of the second segment may have a smaller average grain size and less binder to enhance hardness and wear resistance. Additionally, a compositional gradient may exist within the first segment and/or the second segment of the valve seat. In some embodiments, the cemented hard carbide forming the valve mating surface includes a small average grain size and a lower metal binder content to enhance hardness and wear resistance. The cemented hard carbide composition of the second segment may increase grain size and/or binder content as one progresses away from the valve mating surface to enhance toughness and fracture resistance. In some embodiments, for example, high hardness and high wear resistance cemented hard carbides may extend to a depth of 50 μm to 1mm or 75 to 500 μm in the second segment. Once the desired depth is reached, the cemented hard carbide composition becomes a tougher fracture-resistant composition.

In some embodiments, when the valve mating surface is formed of cemented hard carbide, the surface roughness (R) of the cemented hard carbide _a) Can be 1-15 μm. Surface roughness (R) of cemented carbide _a) It can also be 5-10 μm. The surface roughness of the cemented hard carbide forming the valve mating surface may be achieved by machining, including but not limited to grinding and/or grit blasting techniques. Further, the cemented hard carbide forming the second segment of the valve seat (including the valve mating surface) may exhibit a compressive stress condition of at least 500 MPa. In some embodiments, the cemented hard carbide forming the second segment may have a compressive stress condition selected from table I.

TABLE I-cemented carbide compressive stress (GPa)

≥1
	≥1.5
≥2
	0.5-3
1-2.5

The compressive stress condition of the cemented hard carbide may be a result of the compression imparted by the ring surrounding the second segment and/or machining of the cemented hard carbide to provide a valve mating surface having a desired surface roughness. Compressive stress of cemented carbide may be determined by Sin ²The ψ method is determined by X-ray diffraction. The cemented hard carbide of the valve seat may also exhibit a hardness of 88-94 HRA.

The ring surrounding the second segment may be formed of any suitable material operable to impart a compressive stress condition to the second segment. In some embodiments, the ring is formed of a metal or alloy (such as steel). The ring may also be formed of ceramic or cermet.

In another aspect, a valve seat includes a first segment for insertion into a fluid passage of a fluid end and a second segment extending longitudinally from the first segment, the second segment including a surface roughness (R) _a) A frustoconical valve mating surface of cemented hard carbide of 1-15 μm. In some embodiments, cemented carbide of the valve mating surface is provided as a mosaic ring coupled to a metal or alloy body. In other embodiments, the second segment is formed of cemented hard carbide. The outer diameter of the second section may be greater than the outer diameter of the first section. Alternatively, the outer diameters of the first and second segments are equal or substantially equal. Further, the second segment of the valve seat may optionally be surrounded by a ring as described herein.

In another aspect, a valve seat for a fluid end includes a body including a bore for insertionA first segment in the fluid channel of the fluid end and a second segment extending longitudinally from the first segment. The second segment includes a recess in which a cemented hard carbide insert is positioned, wherein the cemented hard carbide insert includes a valve mating surface and exhibits a compressive stress condition. In some embodiments, the surface roughness (R) of the cemented carbide insert _a) Is 1-15 μm. Fig. 7 illustrates a cemented carbide insert according to some embodiments. The cemented carbide insert 70 includes a frustoconical valve mating surface 71. The cemented hard carbide forming the insert 70 may have any of the compositions and/or properties described above. The cemented carbide inserts may be coupled to a metal or alloy body or shell. The metal or alloy body may form a portion of the first section and the second section of the valve seat. FIG. 8 is a cross-sectional view of a valve seat including a cemented carbide insert coupled to an alloy body or shell according to some embodiments. In the embodiment of fig. 8, the alloy body 82 forms a first segment 81 of the valve seat 80 for insertion into a fluid passage of a fluid end. The alloy body 82 also forms a portion of the second segment 86 and defines a recess 83 in which the cemented carbide insert 70 is positioned. As shown in FIG. 7, the cemented carbide insert 70 includes a surface roughness (R) _a) A frustoconical valve mating surface 71 of 1-15 μm. In some embodiments, R of valve mating surface 71 _aIs 5-10 μm. The cemented carbide insert 70 may be coupled to the alloy body 82 by any desired means, including brazing, sintering, hot isostatic pressing, and/or press fitting. In some embodiments, the inner annular surface of the alloy body in the second segment 86 includes one or more protrusions for engaging grooves on the periphery of the cemented carbide insert 70. In some embodiments, the alloy body 82 may impart a compressive stress condition to the cemented carbide insert 70. For example, the second segment 86 of the alloy body 82 may impart a compressive stress condition to the cemented carbide insert 70. In some embodiments, the cemented hard carbide insert 70 may exhibit a compressive stress having a value selected from table I above. The alloy body 82 may be made of any desired alloyIncluding but not limited to steel and cobalt-based alloys. In the embodiment of fig. 8, the alloy body 82 provides a portion of the second section 86 having an outer diameter D2 that is greater than the outer diameter D1 of the first section 81. In some embodiments, the outer diameter D1 may vary with the taper of the outer surface 84 of the first section 81. There is a curved intersection 88 at the transition of the first segment 81 and the second segment 86. In addition, the larger outer diameter D2 of second segment 86 creates shoulder 87. The shoulder 87 may have a configuration as described herein in fig. 1-2. In other embodiments, the outer diameter D1 of the first segment 81 and the outer diameter D2 of the second segment 86 are equal or substantially equal. In such embodiments where D1 is equal to D2, the outer surface 84 of the body 82 may be cylindrical.

In another aspect, a valve assembly for a fluid end is provided. The valve assembly includes a valve in reciprocating contact with a valve seat including a first section for insertion into a fluid passage of the fluid end and a second section extending longitudinally from the first section, the second section having a frustoconical valve mating surface. In some embodiments, the outer diameter of the second section is greater than the outer diameter of the first section. Alternatively, the outer diameters of the first and second segments may be equal or substantially equal. The second segment may also be enclosed in a ring that imparts a compressive stress condition to the second segment. In some embodiments, the second segment is optionally enclosed in a ring, and the valve mating surface comprises a surface roughness (R |) _a) 1-15 μm cemented hard carbide. In other embodiments, the frustoconical valve mating surface of the second segment is configured as a cemented carbide insert coupled to the metal or alloy body, wherein the cemented carbide has a surface roughness (R) _a) Is 1-15 μm. In such embodiments, the metal or alloy body may impart a compressive stress condition to the cemented carbide insert. In some embodiments, the metal or alloy body forms a first section of the valve seat and provides a recess for a cemented carbide insert in a second section. The valve seat can have any of the features, compositions, and/or properties described herein.

In another aspect, a fluid end is described. The fluid end includes a suction fluid passage and a discharge fluid passageA channel. A valve assembly is positioned in at least one of the suction fluid passage and the discharge fluid passage, the valve assembly including a valve in reciprocating contact with a valve seat. The valve seat includes a first segment for insertion into the suction or discharge fluid passageway and a second segment extending longitudinally from the first segment. The second section includes a frustoconical valve mating surface and is enclosed in a ring that imparts a compressive stress condition to the second section. In some embodiments, the second segment is optionally enclosed in a ring, and the valve mating surface comprises a surface roughness (R |) _a) 1-15 μm cemented hard carbide. In other embodiments, the frustoconical valve mating surface of the second segment is configured as a cemented carbide insert coupled to the metal or alloy body, wherein the cemented carbide has a surface roughness (R) _a) Is 1-15 μm. In such embodiments, the metal or alloy body may impart a compressive stress condition to the cemented carbide insert. Further, the outer diameter of the second section may be greater than the outer diameter of the first section. In other embodiments, the outer diameters of the first and second segments are equal or substantially equal. The valve seat can have any of the features, compositions, and/or properties described herein. In some embodiments, the compressive stress condition of the first segment is substantially equal to the compressive stress condition of the second segment. The compressive stress conditions of the first and second segments are within 10% or within 5% of each other, substantially equal.

Various embodiments of the present invention have been described with the aim of achieving various objects of the invention. It should be recognized that these embodiments are merely illustrative of the principles of the present invention. Various modifications and alterations of this invention will become apparent to those skilled in the art without departing from the spirit and scope of this invention.