CN111795166A - Valves, valve assemblies and their applications - Google Patents

Abstract

The invention discloses a valve, a valve assembly and its application. Valves and valve assemblies are described herein that employ an architecture that reduces degraded wear mechanisms, thereby extending the life of the assembly. In one aspect, the valve includes a head including a circumferential surface and a valve seat mating surface comprising sintered cemented carbide. Leg members extend from the head, wherein the thickness of one or more of the leg members tapers in a direction away from the head to induce laminar fluid flow around the head. In some embodiments, the cemented carbide is an inlay attached to the valve head.

Description

Valves, valve assemblies and their applications

Relevant application data

This application is a continuation-in-part of US Patent Application Serial No. 16/119,513, filed on August 31, 2018.

technical field

The present invention relates to valves and valve assemblies, and in particular, to valves and valve assemblies for fluid end applications.

Background technique

Valves and associated valve assemblies play a key role in the fluid end of high pressure pumps incorporating positive displacement pistons in multiple cylinders. The operating environment of the valve is often harsh due to high pressure and cyclic shock between the valve body and the valve seat. These harsh operating conditions may cause premature failure and/or electrical leakage of the valve assembly. Additionally, the fluid flowing through the fluid end and contacting the valve assembly may contain high concentrations of particulate matter from hydraulic fracturing operations. Additionally, one or more acids and/or other corrosive substances may be present in the fluid/particulate mixture. In hydraulic fracturing, granular slurries are used to maintain crack openings in geological formations after hydraulic pressure is released from the well. In some embodiments, alumina particles are used in slurries due to their higher compressive strength relative to silica particles or sand. Particulate slurries can cause significant wear on the contact surfaces of the valve and seat. Additionally, slurry particles may become trapped in the valve sealing cycle, resulting in further performance degradation of the valve assembly.

SUMMARY OF THE INVENTION

In view of these shortcomings, valves and valve assemblies are described herein that employ an architecture that reduces degrading wear mechanisms, thereby extending the life of the assembly. In one aspect, the valve includes a head including a circumferential surface and a valve seat mating surface. Leg members extend from the head, wherein the thickness of one or more of the leg members tapers in a direction away from the head to induce laminar fluid flow around the head. The valve may also include a seal attached to the circumferential surface of the head. In some embodiments, the outer surface of the seal exhibits a radius of curvature that maintains laminar fluid flow around the valve. Additionally, in some embodiments, the seal may overlap a portion of the valve seat mating surface.

In another aspect, a valve includes a head including a circumferential surface and a valve seat mating surface. A seal is attached to the circumferential surface, wherein the seal is angled with the valve seat mating surface to establish a primary seat contact area on the seal. The main seat contact area may have a location close to the outer circumferential surface of the seal. As further described herein, when the valve is mated with the valve seat, compressive stress can be concentrated at the main seat contact area. In some embodiments, the seal overlaps a portion of the valve seat mating surface.

In another aspect, valve assemblies are described herein. In some embodiments, a valve assembly includes a valve seat and a valve in reciprocating contact with the valve seat, the valve including a head including a circumferential surface and a valve mating surface. Leg members extend from the head, wherein the thickness of one or more of the leg members tapers in a direction away from the head to induce laminar fluid flow around the head. The valve may also include a seal attached to the circumferential surface of the head. In some embodiments, the outer surface of the seal exhibits a radius of curvature that maintains laminar fluid flow around the valve. In some embodiments, the seal may also overlap a portion of the seat mating surface. Additionally, the seal may be angled with the seat mating surface to establish a primary seat contact area on the seal. In some embodiments, the main seat contact area is located proximate the outer circumferential surface of the seal. The primary contact area on the seal may exhibit compressive stress concentrations when mated with the valve seat.

In some embodiments, the valve seat may include a body including a first section for insertion into the fluid passage of the fluid end; and a second section extending longitudinally from the first section, The second section includes a notch in which the wear inlay is located. The wear inlays serve as valve mating surfaces. In some embodiments, the wear-resistant inlay exhibits compressive stress conditions. Furthermore, the first section and the second section of the valve seat may have the same outer diameter or different outer diameters. For example, the outer diameter of the second section may be greater than the outer diameter of the first section. In other embodiments, the valve seat may be formed from a single alloy, thereby avoiding the wear inlay.

In another aspect, methods of controlling fluid flow are also described herein. In some embodiments, a method of controlling fluid flow includes providing a valve assembly including a valve seat and a valve in reciprocating contact with the valve seat. The valve includes a head including a circumferential surface and a valve seat mating surface. Leg members extend from the head, wherein the thickness of one or more of the leg members tapers in a direction away from the head. The valve is out of contact with the valve seat to allow fluid to flow through the assembly, wherein the one or more tapered leg members induce laminar fluid flow around the head. The valve then engages the valve seat to prevent fluid flow through the valve. In some embodiments, a seal is attached to the circumferential surface of the head. The seal may have a radius of curvature that maintains laminar fluid flow around the valve.

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

Description of drawings

FIG. 1 illustrates the main seat contact area of a seal engaged with a valve seat in accordance with some embodiments.

2 illustrates stress distribution of a valve seal in contact with a valve seat, according to some embodiments.

3 illustrates a front view of a valve in accordance with some embodiments.

FIG. 4 is a sectional view B of FIG. 3 .

5 is a cross-sectional view of the valve of FIG. 3 taken along line A-A.

FIG. 6 is a sectional view C of FIG. 5 .

7A-7F illustrate various cross-sectional seal geometries in accordance with some embodiments.

8 is a fluid flow modeling of the valve of FIGS. 3-6 illustrating laminar flow around the valve head, according to some embodiments.

9 is a schematic cross-sectional view of a valve seat in accordance with some embodiments.

10 is a schematic cross-sectional view of a valve seat in accordance with some embodiments.

11 is a bottom plan view of a valve seat in accordance with some embodiments.

12 is a top plan view of a valve seat in accordance with some embodiments.

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

14 is a side elevational view of a valve seat in accordance with some embodiments.

15 is a cross-sectional view of a sintered cemented carbide inlay in accordance with some embodiments.

16 is a cross-sectional view of a valve seat including a sintered carbide inlay connected to an alloy body or sleeve, according to some embodiments.

17 is a cross-sectional view of a valve seat including a sintered carbide inlay connected to an alloy body or sleeve, according to some embodiments.

Detailed ways

The embodiments described herein may be better understood by reference to the following detailed description and examples. However, the elements, apparatus, 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 invention. Numerous modifications and adaptations will be readily apparent to those skilled in the art without departing from the spirit and scope of the invention.

I. Valve

The valve described in this article employs an architecture that reduces degraded wear paths, thereby extending the life of the valve. In one aspect, the valve includes a head including a circumferential surface and a valve seat mating surface. Leg members extend from the head, wherein the thickness of one or more of the leg members tapers in a direction away from the head to induce laminar fluid flow around the head. The leg members may have any taper angle consistent with causing laminar fluid flow around the head. For example, one or more of the legs may have a taper angle of 1 to 10 degrees. In other embodiments, the leg taper angle may be 2 degrees to 5 degrees. The leg members of the valve may exhibit the same taper angle or different taper angles. The taper angle of each leg member can be individually adjusted according to the fluid flow environment of the valve. Alternatively, the taper angles of the leg members may be adjusted in conjunction with each other to induce laminar fluid flow around the head. The leg members may also include rounded and/or flat surfaces. For example, one or more edges of the leg members may be rounded.

The valve may include any desired number of leg members. The number of leg members may be selected based on several considerations including, but not limited to, the fluid flow environment of the valve and the structural parameters of the assembly incorporating the valve. The valve may include 3 to 6 leg members. In some embodiments, the leg members of the valve may exhibit equidistant radial spacing or offsets. In other embodiments, the radial spacing between the leg members may be variable.

A leg member extends from the bottom surface of the valve head. An intermediate body member or stem may reside between the bottom surface of the head and the leg members. The leg members may extend radially from the intermediate body member. In some embodiments, the leg members extend radially at an angle of 45 to 80 degrees relative to the longitudinal axis of the valve. In some embodiments, the leg members extend radially at an angle of 60 to 70 degrees relative to the longitudinal axis of the valve. Each of the leg members may extend radially at the same angle. Alternatively, the leg members may extend radially at different angles relative to the longitudinal axis. Additionally, the transition region between the bottom surface of the valve head and the intermediate body member may exhibit a radius of curvature. The radius of curvature may be in the range of 0.25mm to 5mm. In some embodiments, the transition zone radius of curvature is in the range of 0.5 mm to 2 mm. The radius of curvature can help maintain laminar fluid flow around the head.

The valve may also include a seal attached to the circumferential surface of the head. In some embodiments, the circumferential surface defines an annular groove that engages the seal, the annular groove including a top surface and a bottom surface. The top surface of the annular groove may extend radially beyond the bottom surface. Additionally, the bottom surface of the annular groove may transition to the seat mating surface. In some embodiments, the transition region between the groove bottom surface and the valve seat mating surface has a radius of curvature that is less than the radius of curvature of the annular groove.

The outer surface of the seal may have a radius of curvature that maintains laminar fluid flow around the valve head. Thus, the tapered leg member may work in conjunction with the seal and the intermediate body member to provide laminar fluid flow around the valve head. In some embodiments, the seal overlaps a portion of the seat mating surface. In other embodiments, the seal terminates at the end wall of the seat mating surface and does not overlap a portion of the seat mating surface. The seal may comprise any material consistent with sealing of a valve assembly in a high pressure fluid environment, such as those encountered in the fluid end of a hydraulic fracturing operation. In some embodiments, the seal includes a polymeric material, eg, polyurethane or a polyurethane derivative. In other embodiments, the seal may comprise one or more elastomeric materials alone or in combination with other polymeric materials.

Notably, the seal may form an angle (α) with the seat mating surface. The angle (α) formed with the seat mating surface can create a major area on the seal for contact with the valve seat. The location of this main seat contact area may be close to the outer circumferential surface of the seal. The radial position of the main seat contact area can be changed by changing the angle (α) formed by the seal and seat mating surfaces. For example, the main seat contact area may move radially outward on the seal by increasing the angle or move radially inward by decreasing the angle. For example, the angle (α) between the seal and the seat mating surface may be in the range of 5 degrees to 30 degrees. In some embodiments, the value of α is selected from Table I.

Table I--value of α (degree)

5-25 10-20 8-15 12-17

The primary seat contact area is typically the first area of the seal to contact the valve seat during operation of the valve assembly employing the valve. When the valve is mated to the seat, compressive stress can be highest or concentrated in the main seat contact area. By establishing the primary base contact area, the stress relief and/or dissipation characteristics of the seal can be controlled. In some embodiments, for example, the main seat contact area is located proximate the outer circumferential surface of the seal. By occupying this radially outward position, the main seat contact area can quickly dissipate stress concentrations or steps due to the short energy transfer distance from the outer surface of the seal. In this way, stress steps at inner radial locations are avoided and seal life is enhanced. This technical solution is counter-intuitive based on the general stress management principle, where stress steps should be avoided and the stress spreads uniformly over the entire area of the seal.

As described herein, the valve includes a valve seat mating surface. When the valve assembly employing the valve is in the closed position, the seat mating surface contacts the valve seat. In some embodiments, the valve seat mating surface comprises the same alloy that forms the remainder of the valve. Alternatively, the seat mating surface may include a wear-resistant coating. For example, the wear-resistant cladding may comprise a wear-resistant alloy. Suitable wear resistant alloys include cobalt-based alloys and nickel-based alloys. In some embodiments, the cobalt-based alloy of the cladding has compositional parameters selected from Table II.

Table II--Cobalt-Based Alloys

element Amount (wt%) chromium 5-35 Tungsten 0-35 molybdenum 0-35 nickel 0-20 iron 0-25 manganese 0-2 silicon 0-5 vanadium 0-5 carbon 0-4 boron 0-5 cobalt the rest

In some embodiments, the cobalt-based alloy cladding has compositional parameters selected from Table III.

Table III--Cobalt-Based Alloy Cladding

In some embodiments, the nickel-based alloy cladding may have compositional parameters selected from Table IV.

Table IV - Nickel-Based Alloys

In some embodiments, for example, the nickel-based alloy cladding includes 18 to 23 wt % chromium, 5 to 11 wt % molybdenum, 2 to 5 wt %, 0 to 5 wt % of the sum of niobium and tantalum wt% iron, 0.1 wt% to 5 wt% boron, and the balance nickel. Alternatively, the nickel-based alloy cladding comprises 12 to 20 wt% chromium, 5 to 11 wt% iron, 0.5 to 2 wt% manganese, 0 to 2 wt% silicon, 0 to 1 wt% % copper, 0 to 2 wt % carbon, 0.1 to 5 wt % boron, and the remainder nickel. Additionally, the nickel-based alloy cladding may include 3 wt% to 27 wt% chromium, 0 wt% to 10 wt% silicon, 0 wt% to 10 wt% phosphorus, 0 wt% to 10 wt% iron, 0 wt% to 2 wt% wt % carbon, 0 wt % to 5 wt % boron, and the balance nickel.

In some embodiments, the cobalt-based cladding and/or the nickel-based cladding may be produced by sintered powder metallurgy techniques. In other embodiments, the cobalt-based cladding and nickel-based cladding may be produced according to laser cladding or plasma transferred arc techniques. Additionally, the wear-resistant cladding for the valve mating surfaces can have any desired thickness. For example, the cladding thickness can be selected from Table V.

Table V - Cladding Thickness

≥50μm ≥100μm 100μm to 200μm 500μm to 1mm

The cobalt- or nickel-based cladding may also include hard particles. In such embodiments, the hard particles become entrapped in the alloy matrix formed during sintering or melting of the powder alloy. Suitable hard particles may include particles of metal carbides, metal nitrides, metal carbonitrides, metal borides, metal silicides, cemented carbides, as-cast cemented carbides, intermetallics or other ceramics, or mixtures thereof. In some embodiments, the metal elements of the hard particles include aluminum, boron, silicon, and/or one or more metal elements selected from groups IVB, VB, and VIB of the periodic table. Groups of the periodic table described herein are identified according to CAS designations.

In some embodiments, for example, the hard particles include carbides of tungsten, titanium, chromium, molybdenum, zirconium, hafnium, tantalum, niobium, rhenium, vanadium, boron, or silicon, or mixtures thereof. The hard particles may also include nitrides of aluminum, boron, silicon, titanium, zirconium, hafnium, tantalum, or niobium, including cubic boron nitride, or mixtures thereof. Additionally, in some embodiments, the hard particles include borides, such as titanium diboride, B4C, or tantalum boride, or silicides, such as _MoSi2 or _{Al2O3 — SiN} . The hard particles may include crushed cemented carbide, crushed carbides, crushed nitrides, crushed borides, crushed silicides, or other ceramic particle reinforced metal matrix composites, or combinations thereof. For example, crushed cemented carbide particles may have 2 to 25 wt% metal binder. Additionally, the hard particles may include intermetallic compounds such as nickel aluminide.

The hard particles can be of any size consistent with the objectives of the present invention. In some embodiments, the hard particles have a size distribution in the range of about 0.1 μm to about 1 mm. Hard particles can also exhibit bimodal or multimodal size distributions. The hard particles can have any desired shape or geometry. In some embodiments, the hard particles have spherical, elliptical or polygonal geometries. In some embodiments, the hard particles have irregular shapes, including shapes with sharp edges.

Hard particles may be present in the alloy cladding described herein in any amount inconsistent with the objectives of the present invention. The hard particle loading of the cladding can vary depending on several considerations including, but not limited to, the desired hardness, wear resistance and/or toughness of the cladding. In some embodiments, the hard particles are present in the cladding in an amount ranging from 0.5% to 40% by weight. In some embodiments, the hard particles are present in the cladding in an amount of 1 wt% to 20 wt% or 5 wt% to 20 wt%.

In some embodiments, the cladding is applied directly to the seat engagement area of the valve. As described herein, the cladding may be applied by powder metallurgy techniques involving sintering. In other embodiments, the cladding may be applied by laser cladding or plasma transfer arc. Alternatively, the cladding can be provided as an inlay. For example, the cladding can be pre-fabricated to be embedded to the desired size, with the inlay seated in a recess on the valve body to provide a valve seat mating surface. The inlay may have any of the compositional characteristics described above for the seat mating surface, including cobalt-based alloys, nickel-based alloys, and/or hard particles. The valve seat fit inlay may be press fit and/or metallurgically bonded to the valve body via a brazing alloy.

In some embodiments, the valve seat mating surface includes cemented carbide. Sintered cemented carbide can be applied as a cladding to the seat mating surfaces. Alternatively, cemented carbide can be applied to the valve head as an inlay. For example, sintered cemented carbide inlays can be fabricated separately and brazed or press fit to the valve head. In other embodiments, the cemented carbide inlay is attached to the base or substrate, and the base or substrate is connected to the valve head. The inlay can be coupled to the base or substrate by any desired method. For example, the inlay can be brazed or mechanically fitted to the substrate. Additionally, the base or substrate may be attached to the valve head via various mechanisms including, but not limited to, welding, mechanical locking such as a press fit or shrink fit, and/or the use of adhesives. The valve head may include a recess or other structure for receiving a sintered carbide inlay. In some embodiments, the sintered cemented carbide inlay is provided as a single monolithic piece. Sintered cemented carbide inlays can also be provided as multiple radial segments. Any number of radial segments is contemplated. In some embodiments, providing sintered cemented carbide inlays as multiple radial segments may lengthen the inlays by preventing crack propagation and/or other failure modes that may cause premature failure of inlays having a one-piece construction service life. For example, degradation and/or failure of one radial section may not have any effect on the performance of other radial sections of the inlay.

The cemented carbide forming the inlay of the seat mating surface may comprise tungsten carbide (WC). In some embodiments, 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 metal binder of the cemented carbide may include cobalt or a cobalt alloy. For example, cobalt may be present in the cemented carbide in an amount ranging from 3 to 30 wt%. In some embodiments, cobalt is present in the cemented carbide in an amount from 5 wt% to 12 wt% or in an amount from 6 wt% to 10 wt%. Furthermore, the cemented carbide may exhibit a binder enriched region starting from and extending inward from the surface of the substrate. The sintered cemented carbide of the clad valve mating surfaces and/or inlays may also include one or more additives, 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 form solid solution carbides with the WC of the cemented carbide. In such embodiments, the sintered carbides may include one or more solid solution carbides in an amount ranging from 0.1% to 5% by weight.

In some embodiments, the sintered cemented carbide of the clad valve mating surface or inlay may have a surface roughness (R _a ) of 1 μm to 15 μm. The surface roughness (R _a ) of the cemented carbide may also be 5 μm to 10 μm. The surface roughness of the cemented carbide forming the valve mating surface can be obtained via mechanical manipulations including, but not limited to, grinding and/or grit blasting techniques. Additionally, the cemented carbide of the valve mating surface may exhibit a compressive stress condition of at least 500 MPa or at least 1 GPa.

FIG. 1 illustrates the main seat contact area of a seal engaged with a valve seat in accordance with some embodiments. As illustrated in FIG. 1 , the main seat contact area 11 (circled) is located near or adjacent to the outer circumferential surface 12 of the seal 10 . FIG. 2 illustrates the stress distribution of the seal 10 when in contact with the base 15 . The compressive stress concentration is highest in the main seat contact area 11 and can be quickly dissipated by the adjacent outer surface 12 of the seal 10 .

3 illustrates a front view of a valve in accordance with some embodiments. The valve 30 includes a head 31 and a leg member 32 extending from the head 31 . In the embodiment of Figure 3, there are three leg members 32 with equidistant radial spacing. The thickness of each leg member 32 tapers away from the head 31 to create a laminar fluid flow around the head 31 . FIG. 4 is a sectional view B of FIG. 3 . The taper of the leg member 32 and the rounded edge 33 of the leg member 32 are evident. The valve of FIG. 3 also includes a seal 34 attached to the outer circumferential surface of the head 31 . FIG. 5 is a cross-sectional view of the valve taken along line AA of FIG. 3 . In cross-sectional view, the seal 34 is engaged with an annular groove 35 having a top surface 35a and a bottom surface 35b. _A transition region 35c having a radius of curvature R1 connects the top surface 35a and the bottom surface 35b. Furthermore, the top surface 35a extends radially beyond the bottom surface 35b. In the embodiment of FIG. 5 , the bottom surface 35b transitions to the valve seat mating surface 37 via a transition zone 38 having a radius of curvature R ₂ . In some embodiments, R ₁ is greater than R ₂ . As mentioned above, the valve seat mating surface 37 includes the wear resistant coating 37a. In the embodiment of Figure 3, the valve seat mating surface 37 exhibits a frustoconical geometry. The seal 34 forms an angle (α) with the seat mating surface 37 . As discussed above, the angle (α) may establish the primary seat contact area for the seal 34 . FIG. 6 is cross-sectional view C of FIG. 5 providing enlarged detail of annular groove 35 and associated seal 34 . The outer surface of seal 34a may exhibit a radius of curvature R ₃ for maintaining laminar fluid flow around head 31 .

Referring again to FIG. 5 , the leg members 32 extend radially from the intermediate body member 39 . A curved transition region 40 having a radius of curvature R ₃ is established between the bottom surface of the head 31 and the intermediate body member 39 . This transition zone 40 may have a radius of curvature that assists laminar fluid flow around the head 31 . In other embodiments, the transition region 40 is not curved. 7A-7F illustrate cross-sectional views of various seal geometries and designs in accordance with some embodiments.

FIG. 8 illustrates fluid flow modeling of the valve illustrated in FIGS. 3-6. As illustrated in FIG. 8 , the leg members 32 induce laminar fluid flow around the head 31 . The curved transition region 40 and the curved outer surface 34a of the seal 34 help maintain laminar fluid flow.

In another aspect, a valve includes a head including a circumferential surface and a valve seat mating surface. A seal is attached to the circumferential surface and is angled with the seat mating surface to establish a primary seat contact area on the seal. The main seat contact area may be located proximate the outer circumferential surface of the seal. In some embodiments, the seal overlaps a portion of the seat mating surface. The valve and associated main seat contact area may have any of the compositions, properties and/or functions described above in this Section I. For example, valves and seals may exhibit the architecture and functionality described herein in Figures 1-8.

II. Valve assembly

In another aspect, valve assemblies are described herein. In some embodiments, a valve assembly includes a valve seat and a valve in reciprocating contact with the valve seat, the valve including a head including a circumferential surface and a valve mating surface. Leg members extend from the head, wherein the thickness of one or more of the leg members tapers in a direction away from the head to induce laminar fluid flow around the head. The valve may also include a seal attached to the circumferential surface of the head. In some embodiments, the outer surface of the seal exhibits a radius of curvature that maintains laminar fluid flow around the valve. In some embodiments, the seal may also overlap a portion of the seat mating surface. Additionally, the seal may be angled with the seat mating surface to establish a primary seat contact area on the seal. In some embodiments, the main seat contact area is located proximate the outer circumferential surface of the seal. The primary contact area on the seal can exhibit compressive stress concentrations when mated with the valve seat. The valve used in the valve assembly may have any of the architectures, characteristics and/or compositions described in Section I above. For example, the valve may exhibit the architecture and functionality as described in FIGS. 1-8 herein.

In some embodiments, the valve seat may include a body including a first section for insertion into the fluid passage of the fluid end and a second section extending longitudinally from the first section, the second section The section includes a recess in which a wear inlay is located, wherein the wear inlay includes a valve mating surface. In some embodiments, the wear-resistant inlay exhibits compressive stress conditions. Furthermore, the first section and the second section of the valve seat may have the same outer diameter or different outer diameters. For example, the outer diameter of the second section may be greater than the outer diameter of the first section. In other embodiments, the valve seat may be formed from a single alloy, thereby eliminating the need for wear inlays.

Referring now to FIG. 9, the valve seat 10 includes a first section 11 for insertion into the fluid passage of the fluid end. In the embodiment of FIG. 9 , the first section 11 includes a tapered outer surface 12 and an inner surface 13 generally parallel to the longitudinal axis 14 of the base 10 . In some embodiments, the inner surface 13 may also be tapered. The tapered outer surface 12 may present a variable outer diameter D1 of the first section 11 . Alternatively, the outer surface 12 of the first section 11 is not tapered and remains parallel to the longitudinal axis 14 . In this embodiment, the first section 11 has a static outer diameter D1. The outer surface 12 of the first section may also include one or more notches 15 for receiving an O-ring. One or more O-rings may assist in sealing with the fluid channel walls.

The second section 16 extends longitudinally from the first section 11 . The second section has an outer diameter D2 that is greater than the outer diameter D1 of the first section 11 . In the embodiment of Figure 9, the ring 19 surrounding the second section 16 forms part of the outer diameter D2. In some embodiments, the ring 19 may contemplate having a second segment 16 having an outer diameter greater than that of the first segment 11 . In such an embodiment, the body of the valve seat may be cylindrical, with the addition ring 19 providing the second section 16 with a larger outer diameter D2. Alternatively, as illustrated in Figures 9 and 10, the second section 16, separate from the ring 19, may have an outer diameter D2 that is greater than the outer diameter Dl of the first section.

The shoulder 17 is formed by the larger outer diameter D2 of the second section 16 . In the embodiment of FIG. 9 , the shoulder surface 17 a is generally 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 having a value of 5 degrees to 70 degrees. The design of the shoulder 17 may be selected based on several considerations including, but not limited to, the inlet geometry of the fluid passage and the pressure experienced by the base during operation. For example, in some embodiments, the taper of the shoulder may be provided according to the curvature of the fluid channel inlet with which the shoulder engages. The first section 11 transitions to the second section 16 at a curved intersection 18 . The bend intersection can have any desired radius. In some embodiments, the radius of the bend 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 section and the second section. Furthermore, 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) (eg, D1=D2).

The second section 16 also includes a frustoconical valve mating surface 20 , wherein the second section 16 is surrounded by a ring 19 . In the embodiment of FIG. 9 , the rings 19 are connected to the outer surface of the second section 16 in a concentric arrangement. Ring 19 transmits compressive stress conditions to second section 16 . By placing the second section 16 under compressive stress, the ring 19 may assist in balancing or equalizing the relationship between the first section 11 and the second section 16 when the first section 11 is press fit into the fluid passage of the fluid end stress between. The compressive stress condition may also prevent crack formation and/or propagation in the second section 16, thereby enhancing valve seat life and reducing the occurrence of sudden or severe seat failures. The compressive stress conditions may also enable the use of a harder and more brittle material in the second section 16, eg, a harder and more wear-resistant grade of cemented carbide that forms the valve mating surface.

In the embodiment of FIG. 9 , the ring 19 forms a planar interface with the outer surface or perimeter of the second section 16 . In other embodiments, ring 19 may include one or more protrusions or flanges that reside on the inner annular surface of ring 19 . Protrusions or flanges on the inner ring surface may be press fit into notches or grooves along the perimeter of the second section 16 . This structural arrangement may facilitate proper engagement between the ring 19 and the second section 16 . This structural arrangement may also help retain the second section 16 within the ring 19 during operation of the fluid end. In another embodiment, the second section 16 may include one or more protrusions of the flange for engaging with one or more notches in the inner annular surface of the ring 19 .

10 is a schematic diagram illustrating another embodiment of the valve seat described herein. The valve seat of FIG. 10 includes the same structural features illustrated in FIG. 9 . However, the ring 19 in FIG. 10 at least partially covers the shoulder 17 . For example, the ring 19 may be provided with a radial flange 19a for engaging the shoulder 17 of the second section 16 . In some embodiments, the ring 19 completely covers the shoulder 17 . FIG. 11 is a bottom plan view of a valve seat having the architecture of FIG. 10 . As illustrated in FIG. 11 , the ring 19 is attached to the perimeter of the second section and partially covers the shoulder 17 . FIG. 12 is a top plan view of a valve seat having the architecture of FIG. 10 . The frustoconical valve mating surface 20 transitions into the bore 21 of the valve seat 10 . The ring 19 surrounds the second section 16 , thereby imparting compressive stress conditions to the second section 16 . Thus, compressive stress conditions are transmitted to the valve mating surface 20 , which may help resist crack formation and/or crack propagation in the mating surface 20 . Additionally, FIG. 13 illustrates a perspective view of the valve seat of FIG. 10 . 14 illustrates a side elevational view of a valve seat with no curved intersection between the first section 11 and the second section 16, according to some embodiments.

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

In some embodiments, the second section is formed from a composite material including cemented carbide and alloys. For example, a sintered cemented carbide inlay may be attached to a steel substrate, wherein the sintered cemented carbide inlay forms part or all of the valve mating surface and the steel substrate forms the remainder of the second section. In such embodiments, the cemented carbide inlay may extend radially to contact the ring surrounding the second section, thereby permitting the ring to transmit compressive stress conditions to the cemented carbide inlay. In other embodiments, the steel or alloy substrate includes a recess in which the cemented carbide inlay is located. In this embodiment, the outer edge of the recess is located between the cemented carbide inlay and the ring, wherein the compressive stress transmitted by the ring is transmitted to the cemented carbide inlay through the outer edge.

In some embodiments, the sintered cemented carbide inlay is provided as a single monolithic piece. Sintered cemented carbide inlays can also be provided as multiple radial segments. Any number of radial segments is contemplated. In some embodiments, providing sintered cemented carbide inlays as multiple radial segments may lengthen the inlays by preventing crack propagation and/or other failure modes that may cause premature failure of inlays having a one-piece construction service life. For example, degradation and/or failure of one radial section may not have any effect on other radial sections of the inlay.

The cemented carbide of the valve seat may include tungsten carbide (WC). WC may be present in the sintered carbide in an amount of at least 70% by weight or in an amount of at least 80% by weight. Additionally, the metal binder of the cemented carbide may include cobalt or a cobalt alloy. For example, cobalt may be present in the cemented carbide in an amount ranging from 3 wt% to 20 wt%. In some embodiments, cobalt is present in the sintered cemented carbide of the valve seat in an amount ranging from 5 wt% to 12 wt% or in an amount from 6 wt% to 10 wt%. Additionally, the cemented carbide valve seat may exhibit a binder enriched region starting from and extending inwardly from the surface of the substrate. The cemented carbide of the valve seat may also include one or more additives, 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 form solid solution carbides with the WC of the cemented carbide. In such embodiments, the sintered carbides may include one or more solid solution carbides in an amount ranging from 0.1% to 5% by weight.

In some embodiments, a single stage cemented carbide may be employed to form the first and second sections of the valve seat. In other embodiments, one or more compositional gradients may exist between the cemented carbides of the first and second sections. For example, the cemented carbide of the first section may have a larger average grain size and/or a higher metallic binder content to increase toughness. Conversely, the cemented carbide of the second section 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 and/or second section of the valve seat. In some embodiments, the cemented carbide forming the valve mating surface includes a smaller average grain size and a lower metal binder content to enhance hardness and wear resistance. Proceeding away from the valve mating surface, the sintered cemented carbide composition of the second section can increase the grain size and/or binder content to enhance toughness and flex resistance. In some embodiments, for example, the high hardness and high wear resistance cemented carbide may extend to a depth of 50 μm to 1 mm or 75 μm to 500 μm in the second section. Once the desired depth is reached, the cemented carbide composition changes to a more ductile, flexurally resistant composition.

In some embodiments, when the valve mating surface is formed of cemented carbide, the cemented carbide may have a surface roughness (R _a ) of 1 μm to 15 μm. The surface roughness (R _a ) of the cemented carbide may also be 5 μm to 10 μm. The surface roughness of the cemented carbide forming the valve mating surface can be obtained via mechanical manipulations including, but not limited to, grinding and/or grit blasting techniques. Additionally, the cemented carbide forming the second section of the valve comprising the valve mating surface may exhibit a compressive stress condition of at least 500 MPa. In some embodiments, the cemented carbide forming the second section may have compressive stress conditions selected from Table I.

Table VI--Compression stress of cemented carbide (GPa)

≥1 ≥1.5 ≥2 0.5-3 1-2.5

The compressive stress condition of the cemented carbide may result from the compression transmitted by the ring surrounding the second section and/or mechanically manipulating the cemented carbide to provide a valve mating surface with a desired surface roughness. The compressive stress of cemented carbide can be determined via X-ray diffraction according to the Sin ² ψ method. The sintered cemented carbide of the valve seat can also exhibit a hardness of 88 to 94 HRA.

The ring surrounding the second section may be formed of any suitable material that can be used to impart compressive stress conditions to the second section. In some embodiments, the ring is formed from a metal or alloy such as steel. The ring may also be formed of ceramic, cermet, and/or polymeric materials such as polyurethane.

In another aspect, the valve seat includes a first section for insertion into the fluid passage of the fluid end, and a second section extending longitudinally from the first section, the second section comprising a frustoconical valve The mating surface, the frustoconical valve mating surface, comprises a cemented carbide with a surface roughness (R _a ) of 1 μm to 15 μm. In some embodiments, the sintered cemented carbide of the valve mating surface is provided as an inlay ring attached to a metal or alloy body. In other embodiments, the second section is formed of cemented 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 sections are the same or substantially the same. Additionally, the second section of the valve seat may optionally be surrounded by a ring as described herein.

In another aspect, a valve seat for the fluid end includes a body 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 includes a recess in which the cemented carbide inlay is located, wherein the cemented cemented carbide inlay includes a valve mating surface and exhibits a compressive stress condition. In some embodiments, the cemented carbide inlay has a surface roughness (R _a ) of 1 μm to 15 μm. 15 illustrates a sintered cemented carbide inlay according to some embodiments. The sintered cemented carbide inlay 70 includes a frustoconical valve mating surface 71 . The cemented carbide forming inlay 70 may have any of the compositions and/or properties described above. Sintered carbide inlays can be attached to a metal or alloy body or sleeve. The metal or alloy body may form part of the first section and the second section of the valve seat. 16 is a cross-sectional view of a valve seat including a sintered carbide inlay connected to an alloy body or sleeve, according to some embodiments. In the embodiment of Figure 16, the alloy body 82 forms the first section 81 of the valve seat 80 for insertion into the fluid passage of the fluid end. The alloy body 82 also forms part of the second section 86 and defines a recess 83 in which the cemented carbide inlay 70 is located. As in Figure 15, the sintered cemented carbide inlay 70 includes a frustoconical valve mating surface 71 having a surface roughness (R _a ) of 1 μm to 15 μm. In some embodiments, the _Ra of the valve mating surface 71 is 5 μm to 10 μm. The sintered cemented carbide inlay 70 may be attached to the alloy body 82 by any desired means, including brazing, sintering, heat equalizing, and/or press fitting. In some embodiments, the inner annular surface of the alloy body in the second section 86 includes one or more protrusions for engaging grooves on the perimeter of the sintered cemented carbide inlay 70 . In some embodiments, the alloy body 82 may transmit compressive stress conditions to the sintered cemented carbide inlay 70 . For example, the second section 86 of the alloy body 82 may transmit a compressive stress condition to the sintered cemented carbide inlay 70 . In some embodiments, the cemented carbide inlay 70 may exhibit a compressive stress having a value selected from Table I above. The alloy body 82 may be formed from any desired alloy, including but not limited to steel and cobalt-based alloys. In the embodiment of FIG. 16 , the alloy body 82 provides a portion of the second section 86 having an outer diameter D2 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 . A bend intersection 88 exists at the transition of the first section 81 and the second section 86 . In addition, the larger outer diameter D2 of the second section 86 forms a shoulder 87 . The shoulder 87 may have a configuration as described in FIGS. 9-10 herein. In other embodiments, the outer diameter D1 of the first section 81 and the outer diameter D2 of the second section 86 are the same or substantially the same. In such embodiments where D1 is equal to D2, the outer surface 84 of the body 82 may be cylindrical.

As described herein, the first and second sections of the valve seat may have the same outer diameter or substantially the same outer diameter. In such embodiments, the valve seat exhibits a single outer diameter as compared to the dual outer diameters ( D1 , D2 ) of the valve seat illustrated in FIG. 16 . 17 illustrates a single outer diameter valve seat including a sintered carbide inlay, according to some embodiments. Reference numerals in FIG. 17 correspond to the same components as in FIG. 16 . As illustrated in Figure 17, the valve seat 80 includes a single outer diameter D1. In some embodiments, the valve seat 80 does not utilize the inlay 70 of cemented carbide or other wear resistant material. For example, the valve mating surface may be formed of the same alloy as the rest of the seat body. In some embodiments, a wear resistant coating may be applied to the alloy of the valve mating surface. The wear-resistant cladding may comprise a cobalt- or nickel-based alloy as described herein, or a metal matrix composite. In further embodiments, the outer diameter of the valve seat may taper away from the valve mating surface. For example, the first section of the base may have a larger outer diameter than the second section. However, there is no shoulder between the first and second sections, and the outer diameter tapers linearly inward. Wear inlays or cladding may also be used in embodiments where the outer diameter of the valve seat is tapered without creating a shoulder.

III. Fluid Flow Control

In another aspect, methods of controlling fluid flow are also described herein. In some embodiments, a method of controlling fluid flow includes providing a valve assembly including a valve seat and a valve in reciprocating contact with the valve seat. The valve includes a head including a circumferential surface and a valve seat mating surface. Leg members extend from the head, wherein the thickness of one or more of the leg members tapers in a direction away from the head. The valve is out of contact with the valve seat to allow fluid to flow through the assembly, wherein the one or more tapered leg members induce laminar fluid flow around the head. The valve then engages the valve seat to prevent fluid flow through the valve. In some embodiments, the seal is attached to the circumferential surface of the head. The seal may have a radius of curvature that maintains laminar fluid flow around the valve. The valves and valve seats of the assembly may have any of the architectures, compositions and/or characteristics described in Sections I and II above. For example, the valve and valve seat may exhibit the architecture and function as described in FIGS. 1-17 herein.

Various embodiments of the present invention have been described to achieve the various objects of the present invention. It should be recognized that these embodiments are merely illustrative of the principles of the invention. Numerous modifications and adaptations thereof will be readily apparent to those skilled in the art without departing from the spirit and scope of this invention.

Claims (20)

1. A valve, comprising:

a head comprising a circumferential surface and a valve seat mating surface, the valve seat mating surface comprising a sintered cemented carbide; and

leg members extending from the head, wherein a thickness of one or more of the leg members tapers in a direction away from the head to create a laminar fluid flow around the head.

2. The valve of claim 1, wherein the cemented carbide is an inlay connected to the head.

3. The valve of claim 2, wherein the inlay is a single piece of sintered cemented carbide.

4. The valve of claim 2, wherein the inlay includes a plurality of individual radial segments.

5. The valve of claim 2, wherein the inlay is brazed to a surface of the head.

6. The valve of claim 2, wherein the inlay is mechanically connected to the head.

7. The valve of claim 2, wherein the inlay is attached to a substrate and the substrate is connected to the head.

8. The valve of claim 7, wherein the substrate is connected to the head by at least one of welding, mechanical locking, and adhesive.

9. The valve of claim 2, wherein the head includes an annular groove in which the inlay is located.

10. The valve of claim 1, wherein an intermediate body member is located between the head and leg members.

11. The valve of claim 1, wherein a transition between the intermediate body member and the head has a radius of curvature of 0.5mm to 5 mm.

12. The valve of claim 1, further comprising a seal coupled to the circumferential surface of the head.

13. The valve of claim 12, wherein an outer surface of the seal exhibits a radius of curvature that maintains the laminar fluid flow around the valve.

14. The valve of claim 12, wherein the seal forms an angle with the valve seat mating surface in the range of 5 degrees to 30 degrees.

15. The valve of claim 1, wherein one or more of the legs have a taper angle of 1 to 10 degrees.

16. A valve, comprising:

a head comprising a circumferential surface and a valve seat mating surface, the valve seat mating surface comprising a sintered cemented carbide; and

a seal coupled to the circumferential surface, wherein the seal is angled with respect to the valve seat mating surface to establish a primary seat contact area on the seal proximate an outer circumferential surface of the seal.

17. The valve of claim 16, wherein the angle is in the range of 5 to 30 degrees.

18. The valve of claim 16, wherein the cemented carbide is an inlay connected to the head.

19. The valve of claim 18, wherein the inlay is a single piece of sintered cemented carbide.

20. The valve of claim 18, wherein the inlay includes a plurality of individual radial segments.

Images