Note: Descriptions are shown in the official language in which they were submitted.
VALVES, VALVE ASSEMBLIES AND APPLICATIONS THEREOF
RELATED APPLICATION DATA
The present application is a continuation-in-part of United States Patent
Application
Serial Number 16/119,513 filed August 31, 2018.
FIELD
The present invention relates to valves and valve assemblies and, in
particular, to valves
and valve assemblies for fluid end applications.
BACKGROUND
Valves and associated valve assemblies play a critical role in fluid ends of
high pressure
pumps incorporating positive displacement pistons in multiple cylinders.
Operating
environments of the valves are often severe due to high pressures and cyclical
impact between
the valve body and the valve seat. These severe operating conditions can
induce premature
failure and/or leakage of the valve assembly. Moreover, fluid passing through
the fluid end and
contacting the valve assembly can include high levels of particulate matter
from hydraulic
fracturing operations. Additionally, one or more acids and/or other corrosive
species may be
present in the fluid/particulate mixture. In hydraulic fracturing, a
particulate slurry is employed
to maintain crack openings in the geological formation after hydraulic
pressure from the well is
released. In some embodiments, alumina particles are employed in the slurry
due to higher
compressive strength of alumina relative to silica particles or sand. The
particulate slurry can
impart significant wear on contact surfaces of the valve and valve seat.
Additionally, slurry
particles can become trapped in the valve sealing cycle, resulting in further
performance
degradation of the valve assembly.
SUMMARY
In view of these disadvantages, valves and valve assemblies are described
herein
employing architectures which can mitigate degradative wear mechanisms,
thereby prolonging
life of the assembly. In one aspect, a valve comprises a head including a
circumferential surface
and a valve seat mating surface. Leg members extend from the head, wherein
thickness of one
or more of the leg members tapers in a direction away from the head to induce
laminar fluid flow
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around the head. The valve can also comprise a seal coupled to the
circumferential surface of the
head. In some embodiments, an exterior surface of the seal exhibits a radius
of curvature
maintaining laminar fluid flow around the valve. Additionally, the seal can
overlap a portion of
the valve seat mating surface, in some embodiments.
In another aspect, a valve comprises a head including a circumferential
surface and a
valve seat mating surface. A seal is coupled to the circumferential surface,
wherein the seal
forms an angle with the valve seat mating surface to establish a primary seat
contact area on the
seal. The primary seat contact area can have a location proximate an outer
circumferential
surface of the seal. As described further herein, compressive stress can be
concentrated at the
primary seat contact area when the valve is mated to the valve seat. In some
embodiments, the
seal overlaps a portion of the valve seat mating surface.
In another aspect, valve assemblies are described herein. A valve assembly, in
some
embodiments, comprises a valve seat and a valve in reciprocating contact with
the valve seat, the
valve comprising a head including a circumferential surface and a valve mating
surface. Leg
members extend from the head, wherein 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 can also
comprise a seal coupled to the circumferential surface of the head. In some
embodiments, an
exterior surface of the seal exhibits a radius of curvature maintaining
laminar fluid flow around
the valve. The seal can also overlap a portion of the valve seat mating face,
in some
embodiments. Additionally, the seal can form an angle with the valve seat
mating surface to
establish a primary seat contact area on the seal. In some embodiments, the
primary seat contact
area is located proximate an outer circumferential surface of the seal. When
mated to the valve
seat, the primary contact area on the seal can exhibit a concentration of
compressive stress.
The valve seat, in some embodiments, can comprise a body including a first
section for
insertion into a fluid passageway of a fluid end and a second section
extending longitudinally
from the first section, the second section comprising a recess in which a wear
resistant inlay is
positioned. The wear resistant inlay serves as a valve mating surface. In some
embodiments, the
wear resistant inlay exhibits a compressive stress condition. Moreover, the
first section and the
second section of the valve seat can have the same outer diameter or different
outer diameters.
For example, the outer diameter of the second section can be larger than the
outer diameter of the
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first section. In other embodiments, the valve seat can be formed of a single
alloy composition,
thereby obviating the wear resistant inlay.
In a further aspect, methods of controlling fluid flow are also described
herein. In some
embodiments, a method of controlling fluid flow comprises providing a valve
assembly
comprising a valve seat and a valve in reciprocating contact with the valve
seat. The valve
comprises a head including a circumferential surface and a valve seat mating
surface. Leg
members extend from the head, wherein thickness of one or more of the leg
members tapers in a
direction away from the head. The valve is moved out of contact with the valve
seat to flow
fluid through the assembly, wherein the one or more tapered leg members induce
laminar fluid
.. flow around the head. The valve is subsequently mated with the valve seat
to stop fluid flow
through the valve. In some embodiments, a seal is coupled to the
circumferential surface of the
head. The seal can have a radius of curvature maintaining laminar fluid flow
around the valve.
These and other embodiments are further described in the following detailed
description.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 illustrates a primary seat contact area of a seal engaging a valve seat
according to
some embodiments.
FIG. 2 illustrates a stress profile of a valve seal in contact with a valve
seat according to
some embodiments.
FIG. 3 illustrates an elevational view of a valve according to some
embodiments.
FIG. 4 is sectional view B of FIG. 3.
FIG. 5 is a cross-sectional view of the valve of FIG. 3 along the A-A line.
FIG. 6 is sectional view C of FIG. 5.
FIGS. 7A-7F illustrate various cross-sectional seal geometries according to
some
embodiments.
FIG. 8 is fluid flow modeling of the valve in FIGS. 3-6 illustrating laminar
flow around
the valve head according to some embodiments.
FIG. 9 is a cross-sectional schematic of a valve seat according to some
embodiments.
FIG. 10 is a cross-sectional schematic of a valve seat according to some
embodiments.
FIG. 11 is a bottom plan view of a valve seat according to some embodiments.
FIG. 12 is a top plan view of a valve seat according to some embodiments.
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FIG. 13 is a perspective view of a valve seat according to some embodiments.
FIG. 14 is a side elevational view of a valve seat according to some
embodiments.
FIG. 15 is a cross-sectional view of a sintered cemented carbide inlay
according to some
embodiments.
FIG. 16 is a cross-sectional view of valve seat comprising a sintered cemented
carbide
inlay coupled to an alloy body or casing according to some embodiments.
FIG. 17 is a cross-sectional view of valve seat comprising a sintered cemented
carbide
inlay coupled to an alloy body or casing according to some embodiments.
DETIALED DESCRIPTION
Embodiments described herein can be understood more readily by reference to
the
following detailed description and examples. Elements, apparatus and methods
described herein,
however, 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. Numerous modifications and adaptations
will be readily
apparent to those of skill in the art without departing from the spirit and
scope of the invention.
I. Valves
Valves are described herein employing architectures which can mitigate
degradative wear
pathways, thereby prolonging life of the valves. In one aspect, a valve
comprises a head
including a circumferential surface and a valve seat mating surface. Leg
members extend from
the head, wherein 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. Leg members can have
any taper angle
consistent with inducing laminar fluid flow around the head. For example, one
or more of the
legs can have a taper angle of 1-10 degrees. In other embodiments, leg taper
angle can be 2-5
degrees. Leg members of the valve can exhibit the same taper angle or
differing taper angles.
Taper angle of each leg member may be individually adjusted according to the
fluid flow
environment of the valve. Alternatively, taper angles of the leg members can
be adjusted in
conjunction with one another to induce laminar fluid flow around the head. Leg
members may
also comprise rounded and/or flat surfaces. One or more edges of the leg
members, for example,
can be rounded.
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The valve can comprise any desired number of leg members. Number of leg
members
can be selected according to several considerations including, but not limited
to, the fluid flow
environment of the valve and structural parameters of the assembly
incorporating the valve. A
valve for, can comprise 3-6 leg members. Leg members of the valve can exhibit
equidistant
radial spacing or offset, in some embodiments. In other embodiments, radial
spacing between
the leg members can be variable.
The leg members extend from the bottom surface of the valve head. An
intermediate
body member or trunk may reside between the bottom surface of the head and leg
members. The
leg members may extend radially from the intermediate body member. The leg
members, in
some embodiments, extend radially at an angle of 45 degrees to 80 degrees
relative to the
longitudinal axis of the valve. In some embodiments, the leg members extend
radially at an
angle of 60-70 degrees relative the longitudinal axis of the valve. Each of
the leg members can
radially extend at the same angle. Alternatively, leg members can radially
extend at different
angles relative to the longitudinal axis. Additionally, a transition region
between the bottom
surface of the valve head and intermediate body member can exhibit a radius of
curvature. The
radius of curvature can range from 0.25 mm to 5 mm. In some embodiments, the
transition
region radius of curvature ranges from 0.5 mm to 2 mm. The radius of curvature
can assist with
maintaining laminar fluid flow around the head.
The valve can further comprise a seal coupled to the circumferential surface
of the head.
In some embodiments, the circumferential surface defines an annular groove
engaging the seal,
the annular groove comprising a top surface and bottom surface. The top
surface of the annular
groove can extend radially beyond the bottom surface. Additionally, the bottom
surface of the
annular groove can transition to the valve seat mating surface. The transition
region between the
groove bottom surface and the valve seat mating surface, in some embodiments,
has a radius of
curvature less than the annular groove radius of curvature.
An exterior surface of the seal can have a radius of curvature maintaining
laminar fluid
flow around the valve head. Therefore, the tapered leg members can work in
conjunction with
the seal and intermediate body member to provide laminar fluid flow around the
valve head. In
some embodiments, the seal overlaps a portion of the valve seat mating
surface. In other
embodiments, the seal terminates at an end wall of the valve seat mating
surface and does not
overlap a portion of the valve seat mating surface. The seal can comprise any
material(s)
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. .
. .
consistent with the sealing of valve assemblies in high pressure fluid
environments, such as those
encountered in fluid ends for hydraulic fracturing operations. In some
embodiments, the seal
comprises a polymeric material, such as polyurethane or 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 can form an angle (a) with the valve seat mating surface.
The angle (a)
formed with the valve seat mating surface can establish a primary area on the
seal for contacting
a valve seat. Location of this primary seat contact area can be proximate an
outer
circumferential surface of the seal. Radial location of the primary seat
contact area can be varied
by varying the angle (a) formed by the seal and the valve seat mating surface.
The primary seat
contact area, for example, can be moved radially outward on the seal by
increasing the angle or
moved radially inward by decreasing the angle. The angle (a) between the seal
and the valve
seat mating surface, for example, can range from 5-30 degrees. In some
embodiments, a value of
a is selected from Table I.
Table I ¨ Value of a (degrees)
5-25
10-20
8-15
12-17
The primary seat contact area is generally the first area of the seal to
contact the valve
seat during operation of a valve assembly employing the valve. Compressive
stresses can be the
highest or concentrated in the primary seat contact area when the valve is
mated to the valve seat.
By establishing a primary seat contact area, it possible to control the stress
release and/or
dissipation properties of the seal. In some embodiments, for example, the
primary seat contact
area is located proximate the outer circumferential surface of the seal. By
occupying this
outward radial position, the primary seat contact area can dissipate stress
concentrations or risers
quickly, due to the short energy transfer distance to outer surface of the
seal. In this way, stress
risers at interior radial locations are avoided, and seal lifetime is
enhanced. This technical
solution is counter-intuitive based on general stress management principles
where stress risers
should be avoided, and stress spread evenly over the entire area of the seal.
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. .
. .
As described herein, the valve comprises a valve seat mating surface. The
valve seat
mating surface contacts the valve seat when a valve assembly employing the
valve is in the
closed position. In some embodiments, the valve seat mating surface comprises
the same alloy
forming the remainder of the valve. Alternatively, the valve seat mating
surface can comprise a
wear resistant cladding. The wear resistant cladding, for example, can
comprise a wear resistant
alloy. Suitable wear resistant alloys include cobalt-based alloys and nickel-
based alloys. Cobalt-
based alloy of the cladding have compositional parameters selected from Table
II, in some
embodiments.
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 Balance
In some embodiments, cobalt-based alloy cladding has compositional parameters
selected from
Table III.
Table III ¨ Co-Based Alloy Cladding
Co-Based Alloy Compositional Parameters (wt.%)
Cladding
1 Co-(15-35)%Cr-(0-35)%W-(0-20)%Mo-(0-20)%Ni-(0-25)%Fe-
(0-2)%Mn-(0-5)%Si-
(0-5)%V-(0-4)%C-(0-5)%B
2 Co-(20-35)%Cr-(0-10)%W-(0-10)%Mo-(0-2)%Ni-(0-2)%Fe-(0-
2)%Mn-(0-5)%Si-(0-
2)%V-(0-0.4)%C-(0-5)%B
3 Co-(5-20)%Cr-(0-2)%W-(10-35)%Mo-(0-20)%Ni-(0-5)%Fe-(0-
2)%Mn-(0-5)%Si-(0-
5)%V-(0-0.3)%C-(0-5)%B
4 Co-(15-35)%Cr-(0-35)%W-(0-20)%Mo-(0-20)%Ni-(0-25)%Fe-
(0-1.5)%Mn-(0-2)%Si-
(0-5)%V-(0-3.5)%C-(0-1)%B
5 Co-(20-35)%Cr-(0-10)%W-(0-10)%Mo-(0-1.5)%Ni-(0-1.5)%Fe-
(0-1.5)%Mn-(0-
1.5)%Si-(0-1)%V-(0-0.35)%C-(0-0.5)%B
6 Co-(5-20)%Cr-(0-1)%W-(10-35)%Mo-(0-20)%Ni-(0-5)%Fe-(0-
1)%Mn-(0.5-5)%Si-
(0-1)%V-(0-0.2)%C-(0-1)%B
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Nickel-based alloy cladding, in some embodiments, can have compositional
parameters selected
from Table IV.
Table IV ¨ Nickel-based alloys
Element Amount (wt.%)
Chromium 0-30
Molybdenum 0-28
Tungsten 0-15
Niobium 0-6
Tantalum 0-6
Titanium 0-6
Iron 0-30
Cobalt 0-15
Copper 0-50
Carbon 0-2
Manganese 0-2
Silicon 0-10
Phosphorus 0-10
Sulfur 0-0.1
Aluminum 0-1
Boron 0-5
Nickel Balance
In some embodiments, for example, nickel-based alloy cladding comprises 18-23
wt.%
chromium, 5-11 wt.% molybdenum, 2-5 wt.% total of niobium and tantalum, 0-5
wt.% iron, 0.1-
5 wt.% boron and the balance nickel. Alternatively, nickel-based alloy
cladding comprises 12-20
wt.% chromium, 5-11 wt.% iron, 0.5-2 wt.% manganese, 0-2 wt.% silicon, 0-1
wt.% copper, 0-2
wt.% carbon, 0.1-5 wt.% boron and the balance nickel. Further, nickel-based
alloy cladding can
comprise 3-27 wt.% chromium, 0-10 wt.% silicon, 0-10 wt.% phosphorus, 0-10
wt,% iron, 0-2
wt.% carbon, 0-5 wt.% boron and the balance nickel.
Cobalt-based cladding and/or nickel-based cladding can be produced by sintered
powder
metallurgy techniques, in some embodiments. In other embodiments, cobalt-based
claddings and
nickel-based cladding can be produced according to laser cladding or plasma
transferred arc
techniques. Additionally, wear resistant claddings for the valve mating
surface can have any
desired thickness. For example, cladding thickness can be selected from Table
V.
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Table V ¨ Cladding Thickness
> 50gm
?100gm
100gm-200 gm
500m -1mm
Co-based or Ni-based claddings can further comprise hard particles. In such
embodiments, hard particles become trapped in alloy matrix formed during
sintering or melting
of powder alloy. Suitable hard particles can comprise particles of metal
carbides, metal nitrides,
metal carbonitrides, metal borides, metal suicides, cemented carbides, cast
carbides, intermetallic
compounds or other ceramics or mixtures thereof. In some embodiments, metallic
elements of
hard particles comprise aluminum, boron, silicon and/or one or more metallic
elements selected
from Groups IVB, VB, and VIB of the Periodic Table. Groups of the Periodic
Table described
.. herein are identified according to the CAS designation.
In some embodiments, for example, hard particles comprise carbides of
tungsten,
titanium, chromium, molybdenum, zirconium, hafnium, tantalum, niobium,
rhenium, vanadium,
boron or silicon or mixtures thereof. Hard particles can also comprise
nitrides of aluminum,
boron, silicon, titanium, zirconium, hafnium, tantalum or niobium, including
cubic boron nitride,
or mixtures thereof. Additionally, in some embodiments, hard particles
comprise borides such as
titanium di-boride, B4C or tantalum borides or silicides such as MoSi2 or
A1203¨SiN. Hard
particles can comprise crushed cemented carbide, crushed carbide, crushed
nitride, crushed
boride, crushed suicide, or other ceramic particle reinforced metal matrix
composites or
combinations thereof. Crushed cemented carbide particles, for example, can
have 2 to 25 weight
percent metallic binder. Additionally, hard particles can comprise
intermetallic compounds such
as nickel aluminide.
Hard particles can have any size not inconsistent with the objectives of the
present
invention. In some embodiments, hard particles have a size distribution
ranging from about 0.1
1..tm to about 1 mm. Hard particles can also demonstrate bimodal or multi-
modal size
distributions. Hard particles can have any desired shape or geometry. In some
embodiments,
hard particles have spherical, elliptical or polygonal geometry. Hard
particles, in some
embodiments, have irregular shapes, including shapes with sharp edges.
Hard particles can be present in alloy claddings described herein in any
amount not
inconsistent with the objectives of the present invention. Hard particle
loading of a cladding can
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vary according to several considerations including, but not limited to, the
desired hardness,
abrasion resistance and/or toughness of the cladding. In some embodiments,
hard particles are
present in a cladding in an amount of 0.5 weight percent to 40 weight percent.
Hard particles, in
some embodiments, are present in a cladding in an amount of 1 weight percent
to 20 weight
percent or 5 weight percent to 20 weight percent.
The cladding, in some embodiments, is directly applied the valve seat mating
area of the
valve. As described herein, the cladding can be applied by powder
metallurgical techniques,
including sintering. In other embodiments, the cladding can be applied by
laser cladding or
plasma transferred arc. Alternatively, the cladding can be provided as an
inlay. The cladding,
for example, can be prefabricated to the desired dimensions as an inlay,
wherein the inlay is
disposed in a recess on the valve body to provide the valve seat mating
surface. An inlay can
have any of the compositional properties described above for the valve seat
mating surface,
including Co-based alloys, Ni-based alloys and/or hard particles. A valve seat
mating inlay can
be press-fit and/or metallurgically bonded to the valve body via braze alloy.
In some embodiments, the valve seat mating surface comprises sintered cemented
carbide. The sintered cemented carbide can be applied as a cladding layer to
the valve seat
mating surface. Alternatively, the sintered cemented carbide can be applied as
an inlay on the
valve head. A sintered cemented carbide inlay, for example, can be separately
fabricated and
brazed or press fit to the valve head. In other embodiments, the sintered
cemented carbide inlay
is attached to a base or substrate, and the base or substrate is coupled to
the valve head. The
inlay can be coupled to the base or substrate by any desired method. The
inlay, for example, can
be brazed or mechanically fit to the substrate. Additionally, the base or
substrate can be coupled
to the valve head via a variety of mechanisms including, but not limited to,
welding, mechanical
locking such as press fitting or shrink fitting, and/or use of an adhesive.
The valve head may
comprise a recess or other structure for receiving the sintered cemented
carbide inlay. In some
embodiments, the sintered cemented carbide inlay is provided as a single,
monolithic piece. The
sintered cemented carbide inlay may also be provided as a plurality of radial
sections. Any
number of radial sections is contemplated. Providing the sintered cemented
carbide inlay as a
plurality of radial sections can prolong inlay life, in some embodiments, by
precluding crack
propagation and/or other failure modes that can induce premature failure of
inlays with single
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piece construction. Degradation and/or failure of one radial section, for
example, may not have
any bearing on performance of other radial sections of the inlay.
Sintered cemented carbide of the inlay forming the valve seat mating surface
can
comprise tungsten carbide (WC). In some embodiments, WC can be present in the
sintered
carbide in an amount of at least 70 weight percent or in an amount of at least
80 weight percent.
Additionally, metallic binder of the cemented carbide can comprise cobalt or
cobalt alloy.
Cobalt, for example, can be present in the sintered cemented carbide in an
amount ranging from
3 weight percent to 30 weight percent. In some embodiments, cobalt is present
in the sintered
cemented carbide in an amount ranging from 5-12 weight percent or from 6-10
weight percent.
Further, the sintered cemented carbide may exhibit a zone of binder enrichment
beginning at and
extending inwardly from the surface of the substrate. Sintered cemented
carbide of the cladded
valve mating surface and/or inlay can also comprise one or more additives such
as, for example,
one or more of the following elements and/or their compounds: 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 WC
of the sintered cemented carbide. In such embodiments, the sintered carbide
can comprise one or
more solid solution carbides in an amount ranging from 0.1-5 weight percent.
Sintered cemented carbide of the cladded valve mating surface or inlay can
have surface
roughness (Ra) of 1-15 m, in some embodiments. Surface roughness (Ra) of the
sintered
cemented carbide can also be 5-10 [im. Surface roughness of sintered cemented
carbide forming
the valve mating surface may be obtained via mechanical working including, but
not limited to,
grinding and/or blasting techniques. Moreover, sintered cemented carbide of
the valve mating
surface can exhibit a compressive stress condition of at least 500 MPa or at
least 1GPa.
FIG. 1 illustrates the primary seat contact area of a seal engaging a valve
seat according
to some embodiments. As illustrated in FIG. 1, the primary seat contact area
11 (circled) is
located proximate or adjacent to the outer circumferential surface 12 of the
seal 10. FIG. 2
illustrates a stress profile of the seal 10 when in contact with the seat 15.
Compressive stress
concentration is highest in the primary seat contact area 11, and can be
quickly dissipated
through the neighboring exterior surface 12 of the seal 10.
FIG. 3 illustrates an elevational view of a valve according to some
embodiments. The
valve 30 comprises a head 31 and leg members 32 extending from the head 31. In
the
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embodiment of FIG. 3, three leg members 32 are present having equidistant
radial spacing.
Thickness of each leg member 32 tapers in a direction away from the head 31 to
produce laminar
fluid flow around the head 31. FIG. 4 is sectional view B of FIG. 3. The taper
of the leg
member 32 is evident along with rounded edges 33 of the leg members 32. The
valve of FIG. 3
also comprises a seal 34 coupled to the outer circumferential surface of the
head 31. FIG. 5 is a
cross-sectional view of the valve taken along the A-A line of FIG. 3. In the
cross-sectional view,
the seal 34 engages an annular groove 35 having a top surface 35a and a bottom
surface 35b. A
transition region 35c having radius of curvature R1 connects the top 35a and
bottom 35b
surfaces. Moreover, 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 region 38 having a radius of curvature R2. In some embodiments,
R1 is greater than
R2. As described above, the valve seat mating surface 37 comprises a wear
resistant cladding
37a. In the embodiment of FIG. 3, the valve seat mating surface 37 exhibits
frustoconical
geometry. The seal 34 forms an angle (a) with the valve seat mating surface
37. The angle (a)
can establish a primary seat contact area for the seal 34, as described above.
FIG. 6 is Sectional
view C of FIG. 5 providing magnified detail of the annual groove 35 and
associated seal 34. The
exterior surface of the seal 34a can exhibit a radius of curvature R3 for
maintaining laminar fluid
flow around the head 31.
Referring once again to FIG. 5, the leg members 32 extend radially from an
intermediate
body member 39. A curved transition region 40 having radius of curvature R3 is
established
between the bottom surface of the head 31 and the intermediate body member 39.
This transition
region 40 can have a radius of curvature assisting laminar fluid flow around
the head 31. In
other embodiments, the transition region 40 is not curved. FIGS. 7A-7F
illustrate cross-sectional
views of various seal geometries and designs according to 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 exterior surface 34a of the seal 34 assist
in maintaining the
laminar fluid flow.
In another aspect, a valve comprises a head including a circumferential
surface and a
valve seat mating surface. A seal is coupled to the circumferential surface
and forms an angle
with the valve seat mating surface to establish a primary seat contact area on
the seal. The
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. .
. .
primary seat contact area can be located proximate an outer circumferential
surface of the seal.
In some embodiments, the seal overlaps a portion of the valve seat mating
surface. The valve
and associated primary seat contact area can have any composition, properties
and/or function
described above in this Section I. The valve and seal, for example, can
exhibit the architecture
and function as described in FIGS. 1-8 herein.
II. Valve Assemblies
In another aspect, valve assemblies are described herein. A valve assembly, in
some
embodiments, comprises a valve seat and a valve in reciprocating contact with
the valve seat, the
valve comprising a head including a circumferential surface and a valve mating
surface. Leg
members extend from the head, wherein 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 can also
comprise a seal coupled to the circumferential surface of the head. In some
embodiments, an
exterior surface of the seal exhibits a radius of curvature maintaining
laminar fluid flow around
the valve. The seal can also overlap a portion of the valve seat mating face,
in some
embodiments. Additionally, the seal can form an angle with the valve seat
mating surface to
establish a primary seat contact area on the seal. In some embodiments, the
primary seat contact
area is located proximate an outer circumferential surface of the seal. When
mated to the valve
seat, the primary contact area on the seal can exhibit a concentration of
compressive stress.
Valves for use in valve assemblies can have any architecture, properties
and/or composition
described in Section I above. The valve, for example, can exhibit architecture
and function as
described in FIGS. 1-8 herein.
The valve seat, in some embodiments, can comprise a body including a first
section for
insertion into a fluid passageway of the fluid end and a second section
extending longitudinally
from the first section, the second section comprising a recess in which a wear
resistant inlay is
positioned, wherein the wear resistant inlay comprises a valve mating surface.
In some
embodiments, the wear resistant inlay exhibits a compressive stress condition.
Moreover, the
first section and the second section of the valve seat can have the same outer
diameter or
different outer diameters. For example, the outer diameter of the second
section can be larger
than the outer diameter of the first section. In other embodiments, the valve
seat can be formed
of a single alloy composition, thereby obviating the wear resistant inlay.
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. .
Referring now to FIG. 9, a valve seat 10 comprises a first section 11 for
insertion into a
fluid passageway of the fluid end. In the embodiment of FIG. 9, the first
section 11 comprises a
tapered outer surface 12 and an inner surface 13 that is generally parallel to
the longitudinal axis
14 of the seat 10. In some embodiments, the inner surface 13 may also be
tapered. The tapered
outer surface 12 can 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 such an embodiment, the first section 11 has a static outer
diameter Dl. The outer
surface 12 of the first section may also comprise one or more recesses 15 for
receiving an 0-ring.
One or more 0-rings can aid in sealing with the fluid passageway wall.
A second section 16 extends longitudinally from the first section 11. The
second section
has an outer diameter D2 that is larger than outer diameter D1 of the first
section 11. In the
embodiment of FIG. 9, a ring 19 encasing the second section 16 forms part of
the outer diameter
D2. In some embodiments, the ring 19 can account for the second section 16
having an outer
diameter greater than the first section 11. In such embodiments, the body of
the valve seat can
be cylindrical, where the addition of the ring 19 provides the second section
16 the larger outer
diameter D2. Alternatively, as illustrated in FIGS. 9 and 10, the second
section 16 independent
of the ring 19 can have an outer diameter D2 greater than the outer diameter
D1 of the first
section.
A shoulder 17 is formed by the larger outer diameter D2 of the second section
16. In the
embodiment of FIG. 9, the shoulder surface 17a is generally normal to the
longitudinal axis 14 of
the valve seat 10. In other embodiments, the shoulder surface 17a can taper
and/or form an angle
with the longitudinal axis having a value of 5-70 degrees. Design of the
shoulder 17 can be
selected according to several considerations including, but not limited to,
entrance geometry of
the fluid passageway and pressures experienced by the seat when in operation.
In some
embodiments, for example, taper of the shoulder can be set according to
curvature of the fluid
passageway entrance engaging the shoulder. The first section 11 transitions to
the second
section 16 at a curved intersection 18. The curved intersection can have any
desired radius.
Radius of the curved intersection, in some embodiments, can be 0.05 to 0.5
times the width of
the shoulder. In other embodiments, a curved transition is not present between
the first and
second sections. Moreover, in some embodiments, the outer diameter (D2) of the
second section
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(16) is equal or substantially equal to the outer diameter (D1) of the first
section (11) (e.g. D1 =
D2).
The second section 16 also comprises a frusto-conical valve mating surface 20,
wherein
the second section 16 is encased by a ring 19. In the embodiment of FIG. 9,
the ring 19 is
coupled to the outer surface of the second section 16 in a concentric
arrangement. The ring 19
imparts a compressive stress condition to the second section 16. By placing
the second section
16 in compressive stress, the ring 19 can assist in balancing or equalizing
stress between the first
section 11 and second section 16 when the first section 11 is press fit into a
fluid passageway of
the fluid end. A compressive stress condition can also inhibit crack formation
and/or
propagation in the second section 16, thereby enhancing lifetime of the valve
seat and reducing
occurrences of sudden or catastrophic seat failure. A compressive stress
condition may also
enable the use of harder and more brittle materials in the second section 16,
such as harder and
more wear resistant grades of cemented carbide forming 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, the ring 19 may
comprise one or
more protrusions or flanges residing 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
section 16. This structural arrangement can assist in proper engagement
between the ring 19 and
second section 16. This structural arrangement may also assist in retaining
the second section 16
within the ring 19 during operation of the fluid end. In a further embodiment,
the second section
16 can comprise one or more protrusions of flanges for engaging one or more
recesses in the
interior annular surface of the ring 19.
FIG. 10 is a schematic illustrating another embodiment of a valve seat
described herein.
The valve seat of FIG. 10 comprises the same structural features illustrated
in FIG. 9. However,
the ring 19 in FIG. 10 at least partially covers the shoulder 17. The ring 19,
for example, can be
provided a radial flange 19a for interfacing the shoulder 17 of the second
section 16. In some
embodiments, the ring 19 fully 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 coupled 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 frusto-conical valve
mating surface 20
transitions into the bore 21 of the valve seat 10. The ring 19 encases the
second section 16,
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imparting a compressive stress condition to the second section 16.
Accordingly, a compressive
stress condition is imparted to the valve mating surface 20, which can assist
in resisting crack
formation and/or crack propagation in the mating surface 20. Moreover, FIG. 13
illustrates a
perspective view of the valve seat of FIG. 10. FIG. 14 illustrates a side
elevational view of a
valve seat according to some embodiments, wherein a curved intersection does
not exist between
the first section 11 and second section 16.
As described herein, the valve seat can comprise sintered cemented carbide. In
some
embodiments, the first and second section of the valve seat are each formed of
sintered cemented
carbide. Alternatively, the first section can be formed of metal or alloy,
such as steel or cobalt-
based alloy, and the second section is formed of sintered cemented carbide.
Forming the second
section of sintered cemented carbide can 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 of a composite comprising
sintered
cemented carbide and alloy. For example, a sintered cemented carbide inlay can
be coupled to a
steel substrate, wherein the sintered cemented carbide inlay forms a portion
or all of the valve
mating surface, and the steel substrate forms the remainder of the second
section. In such
embodiments, the sintered carbide inlay can extend radially to contact the
ring encasing the
second section, thereby permitting the ring to impart a compressive stress
condition to the
sintered carbide inlay. In other embodiments, the steel or alloy substrate
comprises a recess in
which the sintered carbide inlay is positioned. In this embodiment, the outer
rim of the recess is
positioned between the sintered carbide inlay and ring, wherein compressive
stress imparted by
the ring is transmitted through the outer rim to the sintered carbide inlay.
In some embodiments, the sintered cemented carbide inlay is provided as a
single,
monolithic piece. The sintered cemented carbide inlay may also be provided as
a plurality of
radial sections. Any number of radial sections is contemplated. Providing the
sintered cemented
carbide inlay as a plurality of radial sections can prolong inlay life, in
some embodiments, by
precluding crack propagation and/or other failure modes that can induce
premature failure of
inlays with single piece construction. Degradation and/or failure of one
radial section, for
example, may not have any bearing on other radial sections of the inlay.
Sintered cemented carbide of the valve seat can comprise tungsten carbide
(WC). WC
can be present in the sintered carbide in an amount of at least 70 weight
percent or in an amount
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of at least 80 weight percent. Additionally, metallic binder of cemented
carbide can comprise
cobalt or cobalt alloy. Cobalt, for example, can be present in the sintered
cemented carbide in an
amount ranging from 3 weight percent to 20 weight percent. In some
embodiments, cobalt is
present in sintered cemented carbide of the valve seat in an amount ranging
from 5-12 weight
percent or from 6-10 weight percent. Further, sintered cemented carbide valve
seat may exhibit
a zone of binder enrichment beginning at and extending inwardly from the
surface of the
substrate. Sintered cemented carbide of the valve seat can also comprise one
or more additives
such as, for example, one or more of the following elements and/or their
compounds: 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 WC of the sintered cemented carbide. In such
embodiments, the sintered
carbide can comprise one or more solid solution carbides in an amount ranging
from 0.1-5
weight percent.
In some embodiments, a single grade of sintered cemented carbide can be
employed to
form the first and second sections of the valve seat. In other embodiments,
one or more
compositional gradients can exist between sintered cemented carbide of the
first section and
second section. For example, sintered cemented carbide of the first section
may have larger
average grain size and/or higher metallic binder content to increase
toughness. In contrast,
sintered cemented carbide of the second section may have smaller average grain
size and less
binder for enhancing hardness and wear resistance. Additionally, a
compositional gradient can
exist within the first and/or second section of the valve seat. In some
embodiments, sintered
cemented carbide forming the valve mating surface comprises small average
grain size and lower
metallic binder content for enhancing hardness and wear resistance.
Progressing away from the
valve mating surface, the sintered cemented carbide composition of the second
section can
increase in grain size and/or binder content to enhance toughness and fracture
resistance. In
some embodiments, for example, sintered cemented carbide of high hardness and
high wear
resistance can extend to a depth of 50 gm- lmm or 75-500 gm in the second
section. Once the
desired depth is reached, the sintered cemented carbide composition changes to
a tougher,
fracture resistant composition.
When the valve mating surface is formed of sintered cemented carbide, the
sintered
cemented carbide can have surface roughness (Ra) of 1-15 gm, in some
embodiments. Surface
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roughness (Ra) of the sintered cemented carbide can also be 5-10 J.Lm. Surface
roughness of
sintered cemented carbide forming the valve mating surface may be obtained via
mechanical
working including, but not limited to, grinding and/or blasting techniques.
Moreover, sintered
cemented carbide forming the second section of the valve seat, including the
valve mating
surface, can exhibit a compressive stress condition of at least 500 MPa. In
some embodiments,
sintered cemented carbide forming the second section can have a compressive
stress condition
selected from Table I.
Table VI¨ Sintered Cemented Carbide Compressive Stress (GPa)
>1
> 1.5
>2
0.5-3
1-2.5
Compressive stress condition of the sintered cemented carbide can result from
compression
imparted by the ring encasing the second section and/or mechanically working
the sintered
cemented carbide to provide a valve mating surface of desired surface
roughness. Compressive
stress of the sintered cemented carbide may be determined via X-ray
diffraction according to the
Sin2w method. Sintered cemented carbide of the valve seat may also exhibit
hardness of 88-94
The ring encasing the second section can be formed of any suitable material
operable to
impart a compressive stress condition to the second section. In some
embodiments, the ring is
formed of metal or alloy, such as steel. The ring may also be formed of
ceramic, cermet and/or
polymeric material, such as polyurethane.
In another aspect, a valve seat comprises a first section for insertion into a
fluid
passageway of a fluid end and a second section extending longitudinally from
the first section,
the second section including a frusto-conical valve mating surface comprising
sintered cemented
carbide having surface roughness (Ra) of 1-15 p.m. In some embodiments, the
sintered cemented
carbide of the valve mating surface is provided as an inlay ring coupled to a
metal or alloy body.
In other embodiments, the second section is formed of the sintered cemented
carbide. The
second section can have an outer diameter greater than the outer diameter of
the first section.
Alternatively, the outer diameters of the first and second sections are equal
or substantially equal.
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Moreover, the second section of the valve seat may optionally be encased by a
ring as described
herein.
In another aspect, a valve seat for use in a fluid end comprises a body
including a first
section for insertion into a fluid passageway of the fluid end and a second
section extending
longitudinally from the first section. The second section comprises a recess
in which a sintered
cemented carbide inlay is positioned, wherein the sintered cemented carbide
inlay comprises a
valve mating surface and exhibits a compressive stress condition. In some
embodiments, the
sintered cemented carbide inlay has surface roughness (Ra) of 1-15 gm. FIG. 15
illustrates a
sintered cemented carbide inlay according to some embodiments. The sintered
cemented carbide
-- inlay 70 comprises a frusto-conical valve mating surface 71. Sintered
cemented carbide forming
the inlay 70 can have any composition and/or properties described above. The
sintered cemented
carbide inlay can be coupled to a metal or alloy body or casing. The metal or
alloy body can
form the first section of the valve seat and a portion of the second section.
FIG. 16 is a cross-
sectional view of valve seat comprising a sintered cemented carbide inlay
coupled to an alloy
-- body or casing according to some embodiments. In the embodiment of FIG. 16,
the alloy body
82 forms the first section 81 of the valve seat 80 for insertion into a fluid
passageway of a fluid
end. The alloy body 82 also forms a portion of the second section 86 and
defines a recess 83 in
which the sintered cemented carbide inlay 70 is positioned. As in FIG. 15, the
sintered cemented
carbide inlay 70 comprises a frusto-conical valve mating surface 71 having
surface roughness of
-- (Ra) of 1-15 gm. In some embodiments, Ra of the valve mating surface 71 is
5-10 gm. The
sintered cemented carbide inlay 70 can be coupled to the alloy body 82 by any
desired means
including brazing, sintering, hot isostatic pressing and/or press fit. In some
embodiments, the
inner annular surface of the alloy body in the second section 86 comprises one
or more
protrusions for engaging a groove on the perimeter of the sintered cemented
carbide inlay 70. In
-- some embodiments, the alloy body 82 can impart a compressive stress
condition to the sintered
cemented carbide inlay 70. The second section 86 of the alloy body 82, for
example, can impart
a compressive stress condition to the sintered cemented carbide inlay 70. The
sintered cemented
carbide inlay 70 can exhibit compressive stress having a value selected from
Table I above, in
some embodiments. The alloy body 82 can be formed of any desired alloy
including, but not
-- limited to, steel and cobalt-based alloy. 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
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. .
. .
diameter D1 of the first section 81. The outer diameter D1 may vary with taper
of the outer
surface 84 of the first section 81, in some embodiments. A curved intersection
88 exists at the
transition of the first section 81 and the second section 86. Additionally,
the larger outer
diameter D2 of the second section 86 creates a shoulder 87. The shoulder 87
may have a
construction as described in FIGS. 9-10 herein. In other embodiments, outer
diameter D1 the
first section 81 and outer diameter D2 of the second section 86 are equal or
substantially equal.
In such embodiments where D1 equals D2, the outer surface 84 of the body 82
can be
cylindrical.
As described herein, the first and second sections of a valve seat can have
the same outer
diameter or substantially the same outer diameter. In such embodiments, the
valve seat exhibits
a single outer diameter in contrast to the dual outer diameters (D1, D2) of
the valve seat
illustrated in FIG. 16. FIG. 17 illustrates a single outer diameter valve seat
comprising a sintered
cemented carbide inlay according to some embodiments. The reference numerals
in FIG. 17
correspond to the same components as in FIG. 16. As illustrated in FIG. 17,
the valve seat 80
comprises single outer diameter, Dl. In some embodiments, the valve seat 80
does not employ
an inlay 70 of sintered cemented carbide or other wear resistant material. The
valve mating
surface, for example, can be formed of the same alloy as the remainder of the
seat body. In some
embodiments, a wear resistant cladding can be applied to alloy of the valve
mating surface. The
wear resistant cladding can comprise cobalt-based or nickel-based alloys
described herein or
metal matrix composite materials. In further embodiments, the outer diameter
of the valve seat
may taper in a direction away from the valve mating surface. The first section
of the seat, for
example, may have a larger outer diameter than the second section. However, a
shoulder is not
present between the first and second sections, and the outer diameter tapers
linearly inward.
Wear resistant inlays or claddings can also be used in embodiments where the
outer diameter of
the valve seat tapers without establishing a shoulder.
III. Fluid Flow Control
In a further aspect, methods of controlling fluid flow are also described
herein. In some
embodiments, a method of controlling fluid flow comprises providing a valve
assembly
comprising a valve seat and a valve in reciprocating contact with the valve
seat. The valve
comprises a head including a circumferential surface and a valve seat mating
surface. Leg
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members extend from the head, wherein thickness of one or more of the leg
members tapers in a
direction away from the head. The valve is moved out of contact with the valve
seat to flow
fluid through the assembly, wherein the one or more tapered leg members induce
laminar fluid
flow around the head. The valve is subsequently mated with the valve seat to
stop fluid flow
through the valve. In some embodiments, a seal is coupled to the
circumferential surface of the
head. The seal can have a radius of curvature maintaining laminar fluid flow
around the valve.
The valve and valve seat of the assembly can have any architecture,
composition and/or
properties described in Sections I and II above. The valve and valve seat, for
example, can
exhibit the architecture and function as described in FIGS. 1-17 herein.
Various embodiments of the invention have been described in fulfillment of the
various
objectives of the invention. It should be recognized that these embodiments
are merely
illustrative of the principles of the present invention. Numerous
modifications and adaptations
thereof will be readily apparent to those skilled in the art without departing
from the spirit and
scope of the invention.
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