Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02258450 1999-01-12
HIGH PRESSURE VALVE
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to valves
and, more particularly, pertains to high pressure
valves.
2. Description of the Prior Art
Conventional high pressure rotary valves,
such as plug and ball valves, generally comprise a
valve body defining a fluid passage in which a rotary
closure member having a bore extending therethrough
is mounted to selectively block or allow the flow of
a fluid. A stem is provided to rotate the closure
member between an open position in which the bore
through the closure member is in alignment with the
fluid passage of the valve body and a closed position
in which the bore through the closure member extends
transversely to the fluid passage of the valve body.
The stem extends from the interior of the valve body
through a stem passage normal to the fluid passage.
Typically, a bonnet is bolted to the valve body for
cooperating with a shoulder provided at the bottom of
the stem to prevent the same from being blown out
when submitted to high internal fluid pressure.
Alternatively, the stem may be inserted through one
end of a single piece valve body and then internally
retained in place by means of an internal abutment
surface defined in the stem passage of the valve body
for cooperating with the shoulder provided at the
bottom of the stem.
Although the above stem and valve body
connections are efficient to prevent the stem from
being blown out of the valve body, they substantially
increase the torque required to operate the valve.
Accordingly, a washer is generally installed between
the stem shoulder and the cooperating abutment
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surface of the valve body in order to reduce the
operating torque. However, in applications where the
processed fluid is at a relatively high temperature,
the installation of such a washer is problematic.
SUMMARY OF THE INVENTION
It is therefore an aim of the present
invention to provide a high pressure valve which
provides stem blowout protection without
significantly increasirig the torque required to
operate the valve.
It is also an aim of the present invention
to provide such a valve which is relatively simple
and economical to manufacture.
Therefore, in accordance with the present
invention there is provided a high pressure valve
comprising a one piece valve body, defining a fluid
passage extending along a flow axis, a closure member
mounted within the valve body and having a bore
extending therethrough. A stem is engaged with the
closure member and extends outwardly of a stem
passage defined in the valve body for rotating the
closure member, about a pivot axis transverse to the
flow axis, between an open position wherein the bore
is coaxially aligned with the fluid passage of the
valve body and a closed position wherein the bore
extends transversally to the fluid passage. A sealing
system is provided for preventing leakage from the
valve body along the stem passage. The high pressure
valve further comprises a stem blowout protection
system including a platform spaced from the valve
body and defining an opening aligned with the stem
passage for receiving the stem therethrough. The
platform and the valve body are of unitary
construction. Bearing means are provided on the stem
between the platform and the valve body outwardly of
the sealing system for cooperating with the platform
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to prevent the stem from being blown out from the
valve body due to fluid pressure within the valve
body.
BRIEF DESCRIPTION OF THE DRAWINGS
Having thus generally described the nature
of the invention, reference will now be made to the
accompanying drawings, showing by way of illustration
a preferred embodiment thereof, and in which:
Fig. 1 is an exploded perspective view of a
ball valve in accordance with the present invention;
Fig. 2 is a longitudinal cross-sectional
view of the ball valve of Fig. 1; and
Fig. 3 is an enlarged cross-sectional view
illustrating the details of a stem assembly of the
ball valve.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Now referring to the drawings, and in
particular to Figs. 1 to 3, a high pressure valve
embodying the elements of the present invention and
generally designated by numeral 10 will be described.
The high pressure valve 10 includes a single piece
valve body 12 defining an axially extending fluid
passage 14 in which a ball valve member 16 is mounted
for selectively blocking and allowing fluid flow
through the valve body 12. The ball valve member 16
has a spherical outer surface and a central bore 18
extending therethrough. The spherical outer surface
of the ball valve member 16 is sealingly engaged with
a downstream valve seat 20 and an upstream valve seat
22. As seen in Fig. 2, the downstream valve seat 20
fits within a recess 24 defined axially inwardly in
the valve body 12 about the fluid passage 14.
A load ring 26 and a spacing insert 28 are
positioned immediately upstream of the upstream valve
seat 22 and a retaining ring 30 is disposed in an
annular groove defined in the valve body 12 about the
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inside of the fluid passage 14 in order to maintain
the upstream valve seat 22, the load ring 26 and the
spacing insert 28 in position within the valve body
12.
The downstream and upstream valve seats 20
and 22 may be formed of metal.
A one piece stem 32 extending through a
stem passage 34 defined in the valve body 12 is
connected at a bottom end thereof to the valve ball
member 16 to rotate the same, about a pivot axis
normal to the fluid passage 14, between an open
position in which the central bore 18 is in axial
alignment with the fluid passage 14 and a closed
position in which the central bore 18 is transversal
to the fluid passage 14. The bottom end of the stem
32 defines two diametrically opposed parallel flats
36 which fit within a slot 38 defined in the upper
surface of the ball valve member 16 to effect
rotation of the ball member 16 upon rotation of the
stem 32.
The stem 32 includes a bottom enlarged
portion 40 adjacent the bottom end defining the flats
36, an intermediate small diameter portion 42
adjacent the bottom enlarged portion 40 defining a
shoulder 44 therebetween, and an enlarged diameter
upper portion 46.
As seen in Fig. 3, the stem passage 34
defines a small diameter inner portion 47 leading to
the fluid passage 14, an intermediate diameter
portion 48 adjacent the small diameter inner portion
47, and an enlarged diameter outer portion 50. A
first shoulder 52 is formed between the small
diameter inner portion 47 and the intermediate
diameter portion 48, while a second shoulder 54 is
formed between the intermediate diameter portion 48
and the enlarged diameter outer portion 50.
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A bushing 56 defining a central passage
therethrough is seated against the first shoulder 52
about the bottom enlarged portion 40 of the stem 32.
The bushing 56 serves as a bearing and a bottom guide
for the stern 32.
The bottom enlarged portion 40 of the stem
32 defines with the enlarged diameter outer portion
50 of the stem passage 34 an annular packing chamber
which is filled by a suitable packing, including two
packing rings 58 disposed between a bottom extrusion
ring 60a and a top extrusion ring 60b, for preventing
leakage from the fluid passage 14 about the stem 32.
The bottom extrusion ring 60a is seated against the
second shoulder 54.
The packing is maintained under axial
compression by a gland assembly 62. The gland
assembly 62 includes a metal split gland bushing 64
mounted on the stem 32 and positioned over the outer
surface of the top extrusion ring 60b. The split
gland bushing 64 defines an axially extending bore 66
(see Fig. 1) which fits against the intermediate
small diameter portion 42 of the stem 32. As seen in
Fig. 1, the split bushing 64 has an open longitudinal
slit 68 which allows it to be spread open and then
placed tightly around the stem 32. As seen in Figs. 2
and 3, an axially extending recess 69 is defined in
the lower end portion of the split gland bushing 64
about the inside of the axially extending bore 66 for
receiving the upper end of the bottom enlarged
portion 40 of the stem 32. As will be explained in
more details hereinafter, the split bushing 64 allows
the stem 32 to be loaded in the valve body 12 through
the stem passage 34 from the outside of the valve
body 12.
The gland assembly 62 further includes a
gland member 70 having a central longitudinal bore 72
(see Fig. 1) through which an upper portion of the
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split gland bushing 64 extends. As best seen in Fig.
3, a recess 74 is formed axially inwardly in the
gland member 70 about the inside of the central bore
66 for receiving three Belleville washers 76 disposed
about the split bushing 62 against an annular
shoulder 78 thereof, thereby providing for a degree
of self-adjustment to compensate for wear of the
packing. As seen in Fig. 1, the gland member 70 is
connected to the valve body 12 by means of a pair of
threaded studs 84 extending through respective
axially extending lateral bores 80 defined in the
gland member 70 and into corresponding bores 82
defined in the portion of the valve body 12
surrounding the stem passage 34. Packing adjustment
nuts 86 are threadably engaged with the upper ends of
the studs 84 to compress the Belleville washers 76
against the shoulder 78 thereby causing the split
gland bushing 64 to apply a compressive load on the
packing.
A platform 86 is remotely connected to the
valve body 12 for cooperating with an annular
shoulder 88 provided at the outer axial end of the
intermediate small diameter portion 42 of the stem
member 32 in preventing the latter from being blown
out from the stem passage 34 due to fluid pressure
inside of the valve body 12. According to a preferred
construction of the present invention, the platform
86 is provided with a pair of lateral elongated
members 90 extending downwardly therefrom to the
outer surface of the valve body 12 on opposed sides
of the stem 32 in order to form an integral platform
and valve body arrangement. In fact, the platform 86
and the elongated members 90 are cast in one piece
with the valve body 12. As seen in Fig. 1, the
platform 86 defines a central bore 92 which is in
coaxial alignment with the stem passage 34 of the
valve body 12 for receiving the stem 32 therethrough.
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A recess 94 is formed in the undersurface of the
platform 86 about the inside of the central bore 92
and defined therewith an annular shoulder 95.
A split bushing 96 defining a central
opening 98 is disposed within the recess 94 about the
enlarged diameter upper portion 46 of the stem 32
against the shoulder 88 thereof. The split bushing 96
is provided with a bottom flange 100 which is in
abutment relationship with the annular shoulder 95 of
the platform 86 to prevent axial removal of the stem
32 from the valve body 12 due to fluid pressure
within the valve body 12. The stem 32, the gland
member 70 and the split gland bushing 64 also
constitute a secondary explosion security, as the
bottom enlarged portion 40 of the stem 32 is larger
than the bore 66 of the split gland bushing 64 which
is disposed within the recess 74 defined in the gland
member 70.
As best seen in Fig.3, the split bushing 96
defined in an upper end portion thereof an axially
extending recess 102 about the inside of the opening
98 for receiving a stem bushing 104 mounted on the
enlarged diameter upper portion 46 of the stem 32. An
axially extending recess 106 is also formed in the
lower end portion of the split bushing 96 about the
inside of the opening 98 for receiving a sealed
thrust bearing 108 mounted on the enlarged diameter
upper portion 46 of the stem 32.
As seen in Fig. 1, a lever 110 defining a
square hole 112 is mounted to the upper square shaped
end of the stem 32. A thrust washer 113 is mounted on
the stem 32 between the lever 110 and the stem
supporting plate 86. A slit 114 extends from the
square hole 112 to one end of the lever 110 opposed
to a handle 116 thereof. A socket head cap screw 118
is inserted in a passage 120 extending transversally
of the slit 114 for cooperating with a nut 122 to
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provide adjustment of the size of the hole 112. A
lock nut 124 is threadably engaged to the end of the
stem 32 to secure the lever 110 to the stem 32.
A stop pin 126 is threadably mounted at a
lower end thereof in a hole 128 defined in the top
surface of the platform 86 to limit the rotation of
the stem 32 by engaging the lever 110 when the ball
member 16 is rotated in the closed position thereof.
A lock clip 130 is mounted for axial
movement along the lever 110 for engaging associated
notches 132 defined in the top surface of the
platform 86 in order to selectively lock the valve 10
in the closed and open positions thereof.
In initial assembly of the valve 10, the
downstream seat 20 is first inserted in place within
the valve body 12 through the upstream end thereof.
Afterwards, the stem bushing 56, the lower anti
extrusion ring 60a, the packing rings 58 and the
upper anti extrusion ring 60b are successively loaded
in the valve body 12 through the stem passage 34.
Thereafter, the stem 32 is inserted through the
central bore 92 of the platform 86 and the gland
member 70 and the Belleville washers 76 are slid
axially onto the lower end of the stem 32 up to the
intermediate small diameter portion 42 thereof. Once
the gland member 70 and the Belleville washers 76
have been mounted on the stem 32, the split gland
bushing 64 is installed in position on the stem 32.
The stem 32 is then pushed downwardly into the stem
passage 34 so as to permit the installation of the
sealed thrust bearing 108, the split bushing 96 and
the stem bushing 104. The sealed thrust bearing 108
is first slid onto the upper end of the stem down
against the shoulder 88. Then, the split bushing 96
is spread open and installed around the stem 32
before the stem bushing 104 be slid onto the upper
end of the stem 32 down into the recess 102 formed in
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the split bushing 96. After having mounted the sealed
thrust bearing 108, the split bushing 96 and the stem
busing 104 on the stem 32, the latter is displaced
upwardly so as to abut the annular flange 100 of the
split bushing 96 against the internal shoulder 95 of
the platform 86. The ball member 16 is then inserted
into the valve body 12 through the upstream end
thereof with the slot 38 extending in the direction
of the flow passage 14 to engage the flats 36 defined
at the bottom end of the stem 32. Thereafter, the
upstream valve seat 22, the load ring 26, the spacing
insert 28 and the retaining ring 30 are installed in
the valve body 12 via the upstream end thereof and
the gland member bolting 84,86 is tightened up.
Finally, the lever 110 is installed on the stem 32
and secured by the lock nut 124. The stop pin 126 may
be virtually fixed at any time to the platform 86.
From the above, it can be seen that the
split bushings 64 and 96 allow the one piece body
stem 32 to be installed within the one piece valve
body 12 through the stem passage 34, while at the
same preventing the stem to be axially removed from
the valve body 12 due to fluid pressure.
One advantage of the above described high
pressure valve 10 is that the one piece body design
eliminates the joints and seals which are potential
leak paths. Furthermore, the stem 32 is retained at a
remote location from the valve body 12, externally of
the packing, and thus the sealed thrust bearing 108,
which ensures low operating torque, is not influence
by the temperature of the processed fluid. This thus
increases the life expectancy of the thrust bearing
108 and consequently increases the reliability of the
high pressure valve 10, while at the same time
providing effective stem blowout protection.
In addition to the above mentioned
advantages, the fact that the platform 86 is integral
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to the one piece valve body 12 ensures perfect
alignment of the stem 32, thereby preventing
premature wear of the stem packing. The fact that the
stem 32 is guided at the bottom end and upper ends
thereof prevents side loads which could damage the
packing and thus cause leakage.
According to another embodiment of the
present invention which is not illustrated, the lever
extends laterally on each side of the stem 32 and is
provided at each end thereof with a handle.
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