U.S. patent number RE29,299 [Application Number 05/743,999] was granted by the patent office on 1977-07-12 for self sealing gate valve.
This patent grant is currently assigned to ACF Industries, Incorporated. Invention is credited to Ralph M. Estes, Robert O. Wynn.
United States Patent |
RE29,299 |
Estes , et al. |
July 12, 1977 |
Self sealing gate valve
Abstract
.Iadd.A gate valve structure having a slab gate member and a
pair of opposed seat assemblies on opposite sides of the gate
member. The seat assemblies loosely fit in recesses in the housing
and the dimensions of the gate member, seat assemblies and housing
recesses are such that there is controlled interference between all
sealing surfaces on assembly. An emergency sealant system provides
emergency sealant to the face of the seat assemblies. .Iaddend.
Inventors: |
Estes; Ralph M. (Houston,
TX), Wynn; Robert O. (Houston, TX) |
Assignee: |
ACF Industries, Incorporated
(New York, NY)
|
Family
ID: |
26796857 |
Appl.
No.: |
05/743,999 |
Filed: |
November 22, 1976 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
Reissue of: |
100162 |
Apr 3, 1961 |
03078865 |
Feb 26, 1963 |
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Current U.S.
Class: |
137/246.22 |
Current CPC
Class: |
F16K
3/36 (20130101); Y10T 137/4442 (20150401) |
Current International
Class: |
F16K
3/36 (20060101); F16K 3/00 (20060101); F16K
003/36 () |
Field of
Search: |
;137/246,246.11,246.12,246.22 ;251/172,174,327,328 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Schwadron; Martin P.
Assistant Examiner: Gerard; Richard
Attorney, Agent or Firm: Riddle; Eugene N.
Claims
What we claim is:
1. A through conduit gate valve comprised of a housing with a bore
therethrough, a valve chamber intersecting said bore, a
reciprocating slab gate member located in said valve chamber, said
gate member provided with a passage alignable with the bore in the
open position and a solid portion to cover said bore in the closed
position, facing annular recesses surrounding said bore, each
recess having an end wall intersecting the bore, an annular wall
coaxial with the bore, one side open to the bore and one end open
to the valve chamber, a seat member in each of said recesses, each
seat member formed of an annular ring having a lesser outer
diameter than the annular wall of its recess whereby each seat
member loosely fits into its recess, each seat member provided with
a passage aligned with the bore, the axial length of each seat
member being greater than the axial length of its recess whereby a
portion of each seat member protrudes into the valve chamber to
form a sealing face for co-operation with a face of the gate
member, each sealing face provided with an annular groove, a
deformable plastic sealing member positioned in said annular
groove, said deformable plastic sealing member extending beyond the
plane of the sealing face to form an annular ring of sealing
contact area, each seat member having an axially outward face which
opposes the end wall of its recess, the radially outer corner of
said axially outward face provided with a rectangular notch which
together with the corner formed by the end wall and the annular
wall of the recess forms a rectangular chamber, a resilient O-ring
positioned in said chamber forming a seal between the seat member
and its recess, said O-ring having an initial outer diameter
approximating the outer diameter of the seat member and a thickness
substantially less than the radial depth of the chamber and greater
than the axial length of the chamber, the gate member, sealing
surfaces of the seat member and the distance between the end walls
of the recesses being so proportioned that there is a slight
interference between all sealing surfaces on assembly, the seat
member having an annular groove about its periphery axially inward
of the corner notch, said groove being generally rectangular in
shape, a resilient O-ring positioned in said annular peripheral
groove, the thickness of said O-ring being such that it is greater
than the radial depth of the groove and less than the axial length
of the groove, said seat member provided with a second annular
groove about its periphery, said second groove positioned between
the first annular peripheral groove and corner notch, the sealing
face of the seat member provided with an annular groove of greater
diameter than the deformable plastic sealing member, a number of
spaced passages connecting the annular groove of the sealing face
with the second annular peripheral groove, the housing provided
with a passage having one end communicating with the second annular
peripheral groove and the other end provided with a lubricant
fitting to permit the introduction of sealant to the sealing face
of the sealing member, the O-ring defining a restraining chamber
whereby the sealant introduced through the fitting is directed into
the second annular peripheral groove, passage and sealing face
annular groove, the differential in the areas of the restraining
chamber being such that there is a resultant force tending to force
the upstream seat forward to more intimate contact with the gate,
the reactive force of the sealant against the gate being of a
lesser magnitude than the force tending to move the seat
forward.
2. A through conduit gate valve comprised of a housing with a bore
therethrough, a valve chamber intersecting said bore, a
reciprocating slab gate member located in said valve chamber, said
gate member provided with a passage alignable with the bore in the
open position and a solid portion to cover said bore in the closed
position, facing annular recesses surrounding said bore, each
recess having an end wall intersecting the bore, an annular wall
coaxial with the bore, one side open to the bore and one end open
to the valve chamber, a seat member in each of said recesses, each
seat member formed of an annular ring having a lesser out diameter
than the annular wall of its recess whereby each seat member
loosely fits into its recess, each seat member provided with a
passage aligned with the bore, the axial length of each seat member
being greater than the axial length of its recess whereby a portion
of each seat member protrudes into the valve chamber to form a
sealing face for cooperation with a face of the gate member, each
sealing face provided with an annular groove, a deformable plastic
sealing member extending beyond the plane of the sealing face to
form an annular ring of sealing contact area, each seat member
having an axially outward face which opposes the end wall of its
recess, the radially outer corner of said axially outward face
provided with a notch which together with the corner formed by the
end wall and the annular wall of the recess forms a chamber, a
resilient O-ring positioned in said chamber forming a seal between
the seat member and its recess, said O-ring having an initial outer
diameter approximating the outer diameter of the seat member and a
thickness greater than the axial length of the chamber, the gate
member, sealing surfaces of the seat member and the distance
between the end walls of the recesses being so proportioned that
there is a slight interference between all sealing surfaces on
assembly, the seat member having an annular groove about its
periphery axially inward of the corner notch, a resilient O-ring
positioned in said annular peripheral groove to form a seal between
the peripheral wall of the seat member and the annular wall of the
recess, said seat member provided with a second annular groove
about its periphery, said second groove positioned between the
first annular peripheral groove and corner notch, the sealing face
of the seat member provided with an annular groove of greater
diameter than the deformable plastic sealing member, a number of
passages connecting the annular groove of the sealing face with the
second annular peripheral groove, the housing provided with a
passage having one end communicating with the scond annular
peripheral groove and the other end provided with a lubricant
fitting to permit the introduction of sealant to the sealing face
of the sealing member, the O-rings defining a restraining chamber
whereby the sealant introduced through the fitting is directed into
the second annular peripheral groove, passage and sealing face
annular groove, the differential in the areas of the restraining
chamber being such that there is a resultant force tending to force
the upstream seat forward to more intimately contact with the gate
and the reactive force of the sealant against the gate being of a
lesser magnitude than the force tending to move the seat
forward.
3. A through conduit gate valve comprised of a housing with a bore
therethrough, a valve chamber intersecting said bore, a
reciprocating slab gate member located in said valve chamber, said
gate member provided with a passage alignable with the bore in the
open position and a solid portion to cover said bore in the closed
position, facing annular recesses surrounding said bore, each
recess having an end wall intersecting the bore, an annular wall
coaxial with the bore, one side open to the bore and one end open
to the valve chamber, a seat member in each of said recesses, each
seat member formed of an annular ring having a lesser outer
diameter than the annular wall of its recess whereby each seat
member loosely fits into its recess, each seat member provided with
a passage aligned with the bore, the axial length of each seat
member being greater than the axial length of its recess whereby a
portion of each seat member protrudes into the valve chamber to
form a sealing face for co-operation with a face of the gate
member, each sealing face provided with an annular groove, a
deformable plastic sealing member positioned in said annular
groove, said deformable plastic sealing member extending beyond the
plane of the sealing face to form an annular ring of sealing
contact area, each seat member having an axially outward face which
opposes the end wall of its recess, the radially outer corner of
said axially outward face provided with a notch which together with
the corner formed by the end wall and the annular wall of the
recess forms a chamber, a resilient O-ring positioned in said
chamber forming a seal between the seat member and its recess, said
O-ring having an initial outer diameter approximating the outer
diameter of the seat member and a thickness greater than the axial
length of the chamber, the seat member having an annular groove
about its periphery axially inward of the corner notch, a resilient
O-ring positioned in said annular peripheral groove to form a seal
between the peripheral wall of the seat member and the annular wall
of the recess, said seat member provided with a second annular
groove about its periphery, said second groove positioned between
the first annular peripheral groove and corner notch, the sealing
face of the seat member provided with an annular groove of greater
diameter than the deforming plastic sealing member, a number of
passages connecting the annular groove of the sealing face with the
second annular peripheral groove, the housing provided with a
passage having one end communicating with the second annular
peripheral groove and the other end provided with a lubricant
fitting to permit the introduction of sealant to the sealing face
of the sealing member, the O-rings defining a restraining chamber
whereby the sealant introduced through the fitting is directed into
the second annular peripheral groove, passage and sealing face
annular groove, the differential in the areas of the restraining
chamber being such that there is a resultant force tending to force
the upstream seat forward to more intimately contact with the gate
and the reactive force of the sealant against the gate not being of
a lesser magnitude than the force tending to move the seat
forward.
4. A through conduit gate valve comprised of a housing with a bore
therethrough, a valve chamber intersecting said bore, a
reciprocating slab gate member located in said valve chamber, said
gate member provided with a passage alignable with the bore in the
open position and a solid portion to cover said bore in the closed
position, facing annular recesses surrounding said bore, each
recess having an end wall intersecting the bore, an annular wall
coaxial with the bore, one side open to the bore and one end open
to the valve chamber, a seat member in each of said recesses, each
seat member formed of an annular ring having a lesser outer
diameter than the annular wall of its recess whereby each seat
member loosely fit into its recess, each seat member provided with
a passage aligned with the bore, the axial length of each seat
member being greater than the axial length of its recess whereby a
portion of each seat member protrudes into the valve chamber to
form a sealing face for co-operation with a face of the gate
member, each sealing face provided with an annular groove, a
deformable plastic sealing member positioned in said annular
groove, said deformable plastic sealing member extending beyond the
plane of the sealing face to form an annular ring of sealing
contact area, each seat member having an axially outward face which
opposes the end wall of its recess, the radially outer corner of
said axially outward face provided with a notch which together with
the corner formed by the end wall and the annular wall of the
recess forms a chamber, a resilient O-ring positioned in said
chamber forming a seal between the seat member an its recess, said
O-ring having an initial outer diameter approximating the outer
diameter of the seat member and a thickness greater than the axial
length of the chamber, the seat member having an annular groove
about its periphery axially inward of the corner notch, a resilient
O-ring positioned in said annular peripheral groove to form a seal
between the peripheral wall of the seat member and the annular wall
of the recess, said seat member provided with a second annular
groove about its periphery, said second groove positioned between
the first annular peripheral groove and corner notch, the sealing
face of the seat member provided with an annular groove of greater
diameter than the deformable plastic sealing member, a number of
passages connecting the annular groove of the sealing face with the
second annular peripheral groove, the housing provided with a
passage having one end communicating with the second annular
peripheral groove and the other end provided with a lubricant
fitting to permit the introduction of sealant to the sealing face
of the sealing member, the O-rings defining a restraining chamber
whereby the sealant introduced through the fitting is directed into
the second annular peripheral groove, passage and sealing face
annular groove, the sealant system being so proportioned that the
forces developed by sealant being injected are such that there is a
resultant force tending to move the seat out of its pocket into an
intimate contact with the gate maintaining the gap between the
sealing faces of the seat and gate at a minimum.
5. A valve comprised of a housing with a bore therethrough, a valve
chamber intersecting said bore, a valve member located in said
valve chamber, said valve member provided with a passage alignable
with the bore in the open position and a solid portion to cover
said bore in the closed position, facing annular recesses
surrounding said bore, each recess having an end wall intersecting
the bore, an annular wall coaxial with the bore, one side open to
the bore and one end open to the valve chamber, a seat member in
each of said recess, each seat member formed of an annular ring
having a lesser outer diameter than the annular wall of its recess
whereby each seat member loosely fits into its recess, each seat
member provided with a passage aligned with the bore, a portion of
each seat member forming a sealing face for co-operation with a
face of the valve member, each sealing face provided with an
annular groove, a deformable plastic sealing member positioned in
said annular groove, said deformable plastic sealing member
extending beyond the plane of the sealing face to form an annular
ring of sealing contact area, each seat member having an axially
outward face which opposes the end wall of its recess, the radially
outer corner of said axially outward face provided with a notch
which together with the corner formed by the end wall and the
annular wall of the recess forms a chamber, a resilient O-ring
positioned in said chamber forming a seal between the seat member
and its recess, said O-ring having an outer diameter approximating
the outer diameter of the seat member and a thickness greater than
the axial length of the chamber, the valve member, sealing surfaces
of the seat members and the distance between the end walls of the
recesses being so proportioned that there is a slight interference
between all sealing surfaces on assembly, the seat member having an
annular groove about its periphery axially inward of the corner
notch, said groove being generally rectangular in shape, a
resilient O-ring positioned in said annular groove, the thickness
of said O-ring being such that it is greater than the radial depth
of the groove and less than the axial length of the groove, said
seat member provided with a second annular groove about its
periphery, said second groove positioned between the first annular
groove and corner notch, the sealing face of the seat member
provided with an annular groove of greater diameter than the
deformable plastic sealing member, a passage connecting the annular
groove of the sealing face with the second annular peripheral
groove, the housing provided with a passage having one end
communicating with the second annular peripheral groove and the
other end provided with a lubricant fitting to permit the
introduction of sealant to the sealing face of the sealing member,
the O-ring defining a restraining chamber whereby the sealant
introduced through the fitting is directed into the annular groove
passage and sealing face annular groove, the differential in the
areas of the restraining chamber being such that there is a
resultant force tending to force the upstream seat forward to move
into intimate contact with the valve member and the reactive force
of the sealant against the valve member being of lesser magnitude
than the force tending to move the seat forward.
6. A through conduit gate valve comprised of a housing with a bore
therethrough, a valve chamber intersecting said bore, a
reciprocating slab gate member located in said valve chamber, said
gate member provided with a passage alignable with the bore in the
open position and a solid portion to cover said bore in the closed
position, facing annular recesses surrounding said bore, each
recess having an end wall intersecting the bore, an annular wall
coaxial with the bore, one side open to the bore and one end open
to the valve chamber, a seat member in each of said recesses, each
seat member formed of an annular hub portion having a lesser outer
diameter than the annular wall of its recess whereby each seat
member loosely fits into its recess, each seat member provided with
a passage aligned with the bore, the axial length of the hub
portion being slightly greater than the axial length of the recess,
each seat member having a flange portion provided with a front face
which protrudes into the valve chamber to form a sealing face for
co-operation with a face of the gate member, and a rear face which
contacts the wall surrounding the recess, each sealing face
provided with an annular groove, a deformable plastic sealing
member positioned in said annular groove, said deformable plastic
sealing member extending beyond the plane of the sealing face to
form an annular ring of sealing contact area, the hub portion of
each seat member having an axially outward face which opposes the
end wall of its recess, the radially outer corner of said axially
outward face provided with a rectangular notch which together with
the corner formed by the end wall and the annular wall of the
recess forms a rectangular chamber, a resilient O-ring positioned
in said chamber forming a seal between the seat member and its
recess, said O-ring having an initial outer diameter approximating
the outer diameter of the seat member and a thickness greater than
the axial length of the chamber, the gate member, sealing surfaces
of the seat member and the distance between the end walls of the
recesses being so proportioned that there is a slight interference
between all sealing surfaces on assembly, an annular groove in the
rear face of the hub portion, said groove being generally
rectangular in shape, a resilient O-ring positioned in said annular
groove, the thickness of said O-ring being such that it is greater
than the axial depth of the groove and less than the radial length
of the groove, said seat member provided with a second annular
groove in the rear face of the hub portion, said second groove
being radially inward of the first annular groove, the sealing face
of the seat member provided with an annular groove of greater
diameter than the deformable plastic sealing member, several
passages connecting the annular groove of the sealing face with the
second annular peripheral groove, the housing provided with a
passage having one end communicating with the second annular
peripheral groove and the other end provided with a lubricant
fitting to permit the introduction of sealant to the sealing face
of the sealing member, the O-ring defining a restraining chamber
whereby the sealant introduced through the fitting is directed into
the annular groove passage and through the passage into several
sealing face annular grooves, the sealant system being so
proportioned that the forces developed by the sealant being
injected are such that there is a resultant force tending to move
the seat out of its pocket into intimate contact with the gate
maintaining the gap between the sealing faces of the seat and gate
at a minimum.
7. A through conduit gate valve comprised of a housing with a bore
therethrough, a valve chamber intersecting said bore, a
reciprocating slab gate member located in said valve chamber, said
gate member provided with a passage alignable with the bore in the
open position and a solid portion to cover said bore in the closed
position, facing annular recesses surrounding said bore, each
recess having an end wall intersecting the bore, an annular wall
coaxial with the bore, one side open to the bore and one end open
to the valve chamber, a seat member in each of said recesses, each
seat member formed of an annular ring having a lesser outer
diameter than the annular wall of its recess whereby each seat
member loosely fits into its recess, each seat member provided with
a passage aligned with the bore, the axial length of each seat
member being greater than the axial length of its recess whereby a
portion of each seat member protrudes into the valve chamber to
form a sealing face for co-operation with a face of the gate
member, each sealing face provided with an annular groove, a
deformable plastic sealing member positioned in said annular
groove, said deformable plastic sealing member extending beyond the
plane of the sealing face to form an annular ring of sealing
contact area, each seat member having an axially outward face which
opposes the end wall of its recess, the radially outer corner of
said axially outward face provided with a rectangular notch which
together with the corner formed by the end wall and the annular
wall of the recess forms a rectangular chamber, a resilient O-ring
positioned in said chamber forming a seal between the seat member
and its recess, said O-ring having an initial outer diameter
approximating the outer diameter of the seat member and a thickness
substantially less than the radial depth of the chamber and greater
than the axial length of the chamber, the gate member, sealing
surfaces of the seat member and the distance between the end walls
of the recesses being so proportioned that there is a slight
interference between all sealing surfaces on assembly. .Iadd. 8. A
through conduit gate valve comprised of a housing with a bore
therethrough, a valve chamber intersecting said bore, a
reciprocating slab gate valve member located in said valve chamber,
said gate member provided with a passage alignable with the bore in
the open position and a solid portion to cover said bore in the
closed position, facing annular recesses surrounding said bore,
each recess having an end wall intersecting the bore, an annular
wall coaxial with the bore, one side open to the bore and one end
open to the valve chamber, a seat member in each of said recesses
to form an upstream seat member and a downstream seat member, each
seat member formed of an annular ring having a lesser outer
diameter than the annular wall of its recess whereby each seat
member loosely fits into its recess, each seat member provided with
a passage aligned with the bore, the axial length of each seat
member being greater than the axial length of its recess whereby a
portion of each seat member protrudes into the valve chamber to
form a sealing face for cooperation with a face of the gate member,
each sealing face provided with an annular groove, a deformable
plastic sealing member positioned in said annular groove, said
deformable plastic sealing member extending beyond the plane of the
sealing face to form an annular ring of sealing contact area for
sealing contact with the gate member, each seat member having an
axially outward face which opposes the end wall of its recess, the
radially outer corner of said axially outward face provided with a
rectangular notch which together with the corner formed by the end
wall and the annular wall of the recess forms a rectangular
chamber, a resilient O-ring consisting solely of a stretchable
elastomeric material positioned in said rectangular chamber forming
a seal between the seat member and its recess, said O-ring having
an initial outer diameter approximating the outer diameter of the
seat member and a thickness substantially less than the radial
depth of the chamber and greater than the axial length of the
chamber such that the O-rings are initially deformed axially upon
assembly to provide the force for initially causing said sealing
contact between the sealing members and said gate member; the gate
member, sealing surfaces of the seat member and the distance
between the end walls of the recesses being so proportioned that
there is a slight interference between all sealing surfaces on
assembly, each seat member having the outward face thereof spaced
from the opposed end wall of the associated recess on assembly and
being exposed to and responsive to fluid pressure from both the
bore and the valve chamber for floating back and forth movement of
the seat members with respect to the gate member and the housing
thereby to provide fluid pressure actuated seat members, said
upstream seat member and its associated plastic sealing member upon
the reaching of an excessive fluid pressure in the valve chamber
being moved out of sealing contact with the gate member to relieve
the excess fluid pressure in the body chamber to the bore, said
O-ring being stretched radially outwardly into sealing engagement
with the annular wall of the associated recess when the fluid
pressure in the bore is greater than the fluid pressure in the
valve chamber. .Iaddend.
Description
This invention relates generally to valves, and more particularly
to a through conduit gate valve having a slab gate member and
cooperating seat members which form a seal both upstream and
downstream.
Gate valves, particularly through conduit gate valves, which when
open present an unbroken smooth wall conduit for uninterrupted
passage of flow therethrough, are widely used because of their
desirable flow characteristics. When in the open position, the
straight-through passage, which is provided, offers no more
appreciable resistance to fluid flow than an equal length of pipe.
Although good flow characteristics are important, an even more
important aspect of any valve is its ability to seal. While in
certain installations it is only necessary for a valve to stop flow
from passing out of the downstream side, there are other
installations where it is necessary that the valve stops flow on
the upstream side thereby blocking flow from entering the valve
chamber. An upstream seal is also necessary for block and bleed
service, i.e., service where the valve chamber can be bled to
indicate leakage past either seat.
In through conduit gate valves, line pressure aids in establishing
a seal at the downstream side by forcing the gate into intimate
contact with the downstream seat member. Generally speaking, since
line pressure at the same time tends to move the gate away from the
upstream seat, it is more difficult to establish an upstream seal.
One method of obtaining effective downstream and upstream seals for
gate valves has been to provide means whereby the gate member is
mechanically forced into sealing engagement with both the upstream
and downstream seats. While such valves provide an effective seal,
they are fairly expensive to manufacture inasmuch as they require
mechanism to expand the gate the necessary amount to obtain a tight
seal in the closed position and also mechanism to retract or
collapse the gate when it is being moved to the open position.
Another deterrent in establishing effective seals is that it is
inherently difficult to establish a bubble tight seal between two
metal surfaces. Several means have been used to alleviate this
condition. One has been to inject a heavy viscous lubricant or
sealant between the two surfaces which will aid in establishing the
seal. However, where sealant is essential to the establishing of a
seal, the necessary constant maintenance to see that the valve is
properly lubricated is time consuming and expensive. Other means
used to effect seals has been the utilization of rubber or other
resilient materials; however, such materials are subject to swell
in many common ladings. O-rings have also been used but they
usually require special fixtures to prevent disengagement when
moving the valve from one position to another. A means which has
been useful in establishing a seal has been providing the sealing
face of the seat member with an annular ring of plastic deformable
material such as polytetrafluoroethylene, commonly available in the
United States under the trademark "Teflon." Such a seal is shown
and described in J. S. Downs et al. U.S. Pats. 2,925,993 and
2,925,994. The utilization of this seal has made more practical the
development of an upstream seal without the use of mechanical
force.
While the Teflon insert makes an excellent seal and provides a low
friction surface for the gate to ride against, it is desirable that
flow can be stopped even though the Teflon insert has been damaged.
In order to accomplish this, the valve of the present invention is
provided with means so that, in an emergency, flow can be stopped
even though the plastic insert or metal surfaces have been
damaged.
The through conduit gate valve of the present invention is
comprised of a housing with a bore therethrough. A valve chamber
intersects the bore and a reciprocating slab gate or valve member
is located in the valve chamber. The gate member is provided with a
passage which is alignable with the bore in the open position
providing the through conduit. A solid portion covers the bore in
the closed position. There are two facing annular recesses
surrounding the bore. In each of the recesses there is positioned a
seat member. Each seat member is formed of an annular ring having a
smaller outer diameter than the wall of the recess whereby each
seat member loosely fits into its recess. Each seat member has a
passage which forms a portion of the bore. The axial length of each
seat member is greater than the axial length of the recess whereby
a portion of the seat member protrudes into the valve chamber
forming a sealing face for co-operation with a face of the gate
member. Each sealing face of the seat member is provided with an
annular groove. Secured in the groove is a Teflon insert forming a
plastic sealing member which extends above the plane of the sealing
face to form an annular ring of sealing contact area. Each seat
member also has an axially outward face which opposes the end wall
of its recess. The radially outer corner of the axially outer face
is provided with a rectangular notch which together with the corner
formed by the end wall and annular wall of the recess forms a
rectangular chamber. A resilient O-ring having an outer diameter
approximating the outer diameter of the seat member and a thickness
substantially less than the radial depth of the chamber and greater
than the axial length of the chamber is located in each chamber.
The gate member, sealing surfaces of the seat member, and the
distance between the end walls of the recesses are so proportioned
that there is a controlled interference between all sealing
surfaces on assembly. Additionally, the O-ring establishes a seal
between the seat member and its recess. On the upstream side, line
pressure will flow in back of the seat where it will be arrested by
the O-ring. Since the Teflon insert has established an initial seal
between the gate and upstream seat, the line pressure will build up
increasing the contact between the Teflon insert and gate resulting
in a tight seal because of the greater pressure area on the back of
the seat. Line pressure will also act on the gate moving it
downstream and due to the line pressure in back of the upstream
seat, the upstream seal will follow maintaining an effective
seal.
To provide emergency lubrication, the seat member has an annular
groove about its periphery axially inward of the corner notch. A
resilient O-ring is positioned therein forming a seal with the
annular wall of the recess. Each seat member is provided with a
second annular groove about its periphery which is positioned
between the first annular peripheral groove and the corner notch.
Also, the sealing face of the seat member is provided with an
annular groove of greater diameter than the deformable plastic
sealing member and a passing connects the annular sealing face
groove with the second annular peripheral groove. The housing is
provided with a passage having one end communicating with the
second annular groove and the other end provided with a lubricant
fitting to permit the introduction of sealant to the sealing face
of the seat members. This permits the injection of sealant to the
sealing face to provide an emergency means of establishing a seal.
These two O-rings form a barrier which directs the sealant through
the passage to the sealing face. The sealant system is so designed
that on the injection of sealant into the valve there will be a
resultant force which moves the seat forward to maintain contact
with the gate. Sealant will not enter and contaminate the lading
since the plastic seal is between the lubricant groove and
bore.
The seat members are so proportioned that if the interial pressure
in the body increases due to such causes as thermal expansion, the
increased pressure will cause the upstream seat to move back in its
pocket permitting the relieving of excessive pressure.
It is an object of the present invention to provide a through
conduit gate valve having a slab gate with pressure activated seat
members provided with a deformable plastic sealing member on their
sealing faces.
It is another object to provide a through conduit gate valve with a
slab gate and pressure activated seat members having a deformable
plastic sealing member on their sealing faces which will relieve
excessive body pressure upstream.
It is another object to provide a through conduit slab gate valve
having pressure acting seats which establish an upstream seal from
either direction.
It is a further object to provide a through conduit gate valve
having pressure acting seats in which there is provision within the
seat members to provide emergency sealant to the face of the
sealing member to provide an emergency seal.
It is still a further object to provide a through conduit gate
valve having pressure acting seat members having deformable plastic
sealing members on their sealing face and provisions whereby in an
emergency sealant can be supplied to the sealing faces to provide
an emergency seal.
It is still a further object to provide a valve having pressure
activated seats with an emergency sealant system which is so
designed that on injection of sealant there will be a resultant
force keeping the seat in contact with the gate.
Other and further objects of the invention will be obvious upon an
understanding of the illustrative embodiments about to be
described, or will be indicated in the appended claims, and various
advantages not referred to herein will occur to one skilled in the
art upon employment of the invention in practice.
Preferred embodiments of the invention have been chosen for purpose
of illustration and description and are shown in the accompanying
drawings, forming a part of the specification, wherein:
FIG. 1 is an elevational view in section illustrating a gate valve
of the present invention.
FIG. 2 is a diagrammatic view of the gate and seat members
illustrating the initial interference on assembly.
FIG. 3 is a view similar to FIG. 2 showing the seals established in
the closed position during normal operation of the valve.
FIG. 4 is a view similar to FIG. 3 showing the pressure actuated
upstream seal when pressure in the body is less than the upstream
pressure.
FIG. 5 is a view similar to FIG. 2 showing the upstream seat member
relieving excessive body pressure.
FIG. 6 is an enlarged cross sectional view of the seat member of
FIG. 1 positioned in a pocket showing the sealant system.
FIG. 7 is a view similar to FIG. 5 of an alternate form of seat
member.
Referring now to the drawings, FIG. 1 illustrates a through conduit
gate valve 8 made in accordance with the present invention. The
gate valve 8 has a housing 10 having a bore 12 therethrough. The
bore 12 forms aligned flow passsages. The outer ends of the flow
passages are shown terminating in flanges which permit the valve 8
to be connected to a flow system. Naturally, any other of the
various well known means of finishing ends for the connection of a
valve to a flow system may be utilized.
Intersecting the bore 12 is a valve chamber 14 in which is located
a reciprocating slab gate member 16. The valve member 16 consists
of a substantially flat metal plate having a passage 18 which is
adapted to register with the bore 12 in the valve open position,
the position shown in FIG. 1, and a solid portion 20 which covers
the bore 12 in the valve closed position, the position shown in
FIGS. 2, 3 and 4. Passage 18 in registering with the bore 12 forms
an unbroken smooth wall conduit for the uninterrupted passage of
flow therethrough which offers no more appreciable resistance to
fluid flow than an equal length of pipe. The upper end of the gate
member 16 is attached to means, such as a stem 22, for raising and
lowering the gate 16. As is well known in the valve art, a bonnet
24 closes the valve chamber 14 and the stem 22 extends through a
sealed passage in the bonnet 24. To move the stem 22 the upper end
thereof is threaded and connectively engaged with a bevel gear
operator 26, handwheel, or any of the various other types of
operations well known in the art.
The valve chamber end of the bores 12 terminates in hub portions
28--28 which extend into the valve chamber 14. The hub portions
28--28 are machined to form annular recesses or seat pockets 30--30
which surround the bore 12. Each recess 30 has an end wall 32 which
intersects the bore 12, an annular wall 34 which is coaxial with
the bore 12. One side of each recess 30 is open to the bore and
there is also an end of the recess which is open to the valve
chamber 14. Positioned in each of the recesses 30 is a
pressure-actuated seat member 36.
Each seat member 36 is formed of an annular ring having a passage
38 which is coaxial with and is the same diameter as the bore 12.
This passage 38 forms a part of the through conduit when the valve
is in the open position. The outer diameter 40 of the seat member
is smaller than the diameter of the annular wall 34 of the recess
whereby each seat member 36 loosely fits into its recess. The axial
length of each seat member is greater than the axial length of its
recess whereby a portion of the seat member protrudes past the end
of the bore past the hub 28 into the valve chamber to form a
sealing face 42 which cooperates with a sealing face 44 of the gate
member 16.
The sealing face 42 of each seat member is provided with an annular
groove 46 in which there is positioned a deformable plastic insert
or sealing member 48. As previously mentioned, the insert is
preferably formed of Teflon. In order to maintain the insert 48 in
the groove 46, it has been found desirable to provide the sides of
the annular groove 46 with a series of thread serrations which grip
the walls of the insert and prohibit its extrusion. The plastic
sealing member 48 extends slightly above the plane of the sealing
face 42 to form an annular ring of sealing contact area. The extent
which the plastic sealing members extend above the plane is in the
neighborhood of .005-.007" which has been found to be
sufficient.
Each seat member 36 has an axial outer face 50 which opposes the
end wall 32 of the recess 30. As previously mentioned, the seat
members 36--36 are pressure actuated. In order to accomplish this
pressure actuation, the radially outer corner of the axially outer
face 50 of each seat member 36 is provided with a rectangular notch
52 which together with a corner formed by the end wall 32 and
annular wall 34 of the recess forms a rectangular chamber 54.
Positioned in the chamber 54 is a resilient O-ring 56 having an
initial outer diameter approximating the outer diameter of the seat
member 36 and a thickness substantially less than the radial depth
of the chamber 54 and greater than the axial length of the chamber
54. The O-ring 56 is a greater thickness than the axial length of
the chamber 54 so that it will extend past the axial outer face 50
of the seat member 36 and form the sealing contact with the end
wall 38 of the recess 30. At the same time the thickness is less
than the radial length of the chamber so that if the O-ring swells
due to a reaction with the lading there will be space to
accommodate such swell. By having the initial outer diameter of the
O-ring 56 approximating the outer diameter of the seat member 36 it
is not necessary to unduly stretch the O-ring during pressure
actuation.
The gate member 16, sealing surfaces of the seat member, that is
the face of the annular plastic ring 48 and the O-ring 56, and the
distance between the end walls 32--32 of the recesses 30--30 are so
proportioned that there is a slight interference between all
sealing surfaces on assembly. This interference establishes an
initial seal and facilitates a differential pressure building up
behind the upstream seat to effect pressure activation thereof. The
O-ring 56 establishes a seal between the seat member 36 and the
annular wall 34 of the recess 30. Therefore, on the upstream side,
line pressure will flow in back of the seat 36 until it is arrested
by the O-ring 56. Since the annular plastic insert 48 has
established an initial seal between the face 44 of the gate and the
sealing face 42 of the upstream seat, the line pressure will build
up increasing the contact between the annular plastic ring 48 and
the sealing surface 44 of the gate resulting in a tight seal. Line
pressure will also act on the gate 16 moving it downstream and due
to the line pressure in back of the upstream seat the upstream seat
36 will follow maintaining an effective seal between the annular
ring 48 of the upstream seat and the sealing face 44 of the gate
16.
In normal operating condition, the contact between deformable
plastic insert 48 and the sealing face 44 of the gate 16 provides a
very tight seal, and no auxiliary means such as constantly
providing lubricant or sealant between the sealing faces of the
seat and gate is necessary.
However, the valve of the present invention is provided with means
which will permit introducing a film of lubricant or sealant
between the sealing faces of the seat members and gate in an
emergency to stop leakage in the event that the annular plastic
insert 48 is damaged or for some other reason the valve will not
seal drop tight. In order to provide this lubrication, seat member
36 is provided with an annular groove 58 about its periphery
axially inward of the corner notch 52. The groove 58 is generally
rectangular in shape and positioned therein is a resilient O-ring
60. The thickness of the O-ring 60 is such that it is greater than
the radial depth of the groove and less than the axial length of
the groove 58. The O-ring 60 establishes a seal between the outer
diameter of the seat member and the annular wall 34 of the recess.
Positioned between the annular groove 58 and the corner notch there
is a second annular groove 62. The sealing face 42 of the seat
member 36 is provided with an annular groove 64 which is of a
greater diameter than the groove 46 containing the annular insert
48. Several passages 66 spaced around the annular groove 64 connect
the annular groove 64 on the sealing face 42 with the second
annular peripheral groove 62. The housing 10 is provided with a
passage 68 which has one end in communication with the second
annular groove 62 and the other end provided with a lubricant
fitting 70. Sealant introduced through the lubricant fitting 70
flows through the groove 68 into and around the annular groove 62
then through the passage 66 and into the annular groove 64 on the
sealing face 42 of the seat where it can form a bridgement with the
sealing face 44 of the gate 16. The two O-rings 56 and 60 form a
barrier which directs the sealant coming through the passage 68
into the annular groove 62 through the passage 66 and into the
annular groove 64. The sealant system is so proportioned that
during the application of sealant the resultant force of the
sealant being introduced through the lubricant fitting 70 results
in a movement of the seat 36 toward the sealing face of the gate
retaining the seat always in constant contact with the sealing face
44 of the gate. The forward movement of the seat results from the
fact the sealant acts on a greater area on the end wall 32 of the
recess 30 than on the sealing face 44 of the gate member 16; and
since pressure is equal in both cases, the larger area at the back
will create a larger force than the reactive force created by the
pressure of the sealant against a smaller area on the sealing face
44 of the gate 16. In other words, sealant will flow through the
passage 68 into and around the annular groove 62. It will then flow
in between the peripheral wall 40 of the seat member 36 and the
annular wall 34 of the recess 30 until it contacts O-rings 60 and
56. The seal at the O-ring 56 will be at the outer diameter of the
seat pocket whereas the seal created by the O-ring 56 will be at
the radial inward end of the corner notch 52. The pressure behind
the sealant will therefore be applied to this area and will tend to
move the seat 36 forward toward the sealing face 44 of the gate 16.
At the same time, sealant will flow through the numerous passages
66 and into the groove 64 where the pressure will be opposed by the
sealing face 44 of the gate 16. The force created at the sealing
face will tend to move the seat member 36 back toward the end wall
32 of the recess 30. However, the area of the groove 64 is smaller
than the area at the back of the seat 36, therefore the force will
be less. There will always be a resultant effect tending to push
the sealing face of the seat tightly against the sealing face of
the gate which will maintain the gap between the two sealing faces
at a minimum thereby enhancing the ability of the sealant to effect
a seal.
As previously mentioned, the various elements in the valve are so
proportioned that upon assembly there will be controlled
interference between the sealing faces 44 of the gate 16 and the
sealing faces of the annular insert 48. Also, the O-ring 56 will be
in sealing contact with rear wall 32 of the pocket 30. This
condition is shown in FIG. 2. Therefore, at extremely low pressures
there will be seals between the annular insert 48 and the sealing
face 44 of the gate and between the seat member 36 and its recess
30.
FIG. 3 shows the seals established during normal operation of the
valve being moved to the closed position with the downstream seat
properly functioning. As can be seen, line pressure will act on the
gate moving it toward the downstream side pushing the seat member
36 back into its pocket 30 where the O-ring 56 will establish a
seal between the recess 30 and the annular wall of the seat member
36 prohibiting fluid from flowing between the seat and its recess.
The annular insert 48 establishes an initial seal with the sealing
face 44 of the gate. If the pressure is sufficiently great, the
gate may be forced into metal-to-metal contact with the downstream
seat causing the annular insert 48 to even more tightly form a seal
with the sealing face of the gate. As previously mentioned, the
initial assembly causes the annular sealing member 48 of the
upstream seat to form a seal with the sealing face 44 on the
upstream side of the gate and there is sufficient compression in
the upstream O-ring 56 that the upstream seat will remain in
contact.
If desired to use the valve for block and bleed service and the
pressure from the valve chamber 16 is bled off, line pressure will
flow between the end wall of the upstream recess and the axial
outer wall of the seat member and will be arrested by the O-ring
56. The line pressure will force the upstream seat out of its
recess into sealing contact with the upstream side face of the
gate. This is particularly true since the area acted upon by the
line pressure on the axially outward side of the upstream gate is
greater than the area acted on by the line pressure on the sealing
face of the gate which only extends from the passage 38 to the
point of contact formed by the annular deformable plastic sealing
ring 48. Accordingly, the higher the line pressure the more
intimate will be the contact between the annular plastic ring 48 of
the upstream seat and the upstream sealing face of the gate 16.
This condition is shown in FIG. 4. The same action will take place
should the downstream seat leak which will cause a pressure
differential actuating the pressure actuated upstream seat.
It has been found that the annular deformable plastic ring 48 will
compensate for most minor scratches and abrasions in the sealing
face of the gate. However, should a portion of the annular plastic
deformable ring 48 become damaged the valve can still be sealed by
the emergency sealant system previously described. In order to
operate the sealant system, a lubricant gun is attached to the
fitting 70 and sealant under pressure is forced through the
lubricant fitting 70 through the passage 68. It then flows around
the annular groove 62 through the various passages 66 to the
annular groove 64 on the sealing face 38 of the seat member. The
sealant used for such purposes is a heavy viscous substance which
is impervious to the lading flowing through the valve and which
will establish a seal between the seat and gate. In order that the
sealant does not force the upstream seat back in its recess and
therefore enlarge the gap between the sealing face of the upstream
seat and the corresponding sealing face of the gate, the sealant
groove system is so proportioned that the injection of sealant will
result in a force which will tend to initially move the seat toward
the gate member rather than back into its pocket 30. Therefore, on
initial injection, the seat 36 will tend to embrace the sealing
face 44 of the gate and the gap will not be of such a magnitude
that the viscous sealant can not effectively seal. On excessive
injection, the sealant will be relieved into the valve chamber 14
since the plastic insert 48 is between the bore 38 and lubricant
groove 64. If injection is continued sufficient pressure will build
up to relieve across the face of the gate preventing body
rupture.
As previously mentioned, the upstream seal will be always forced
against the gate member; however, should the pressure in the body
increase due to thermal expansion as a result in increase of
ambient temperature or for other reasons, the increased pressure
acting on the area of the seat between the outside diameter of the
seat and the annular plastic insert 48 will build up to such a
point that it will momentarily push the seat member 36 back into
the recess allowing the fluid trapped in the body to escape past
the annular insert and thereby relieving the pressure in the body.
The seat has been so proportioned that this will always take place
prior to such an increase in body pressure which would permanently
deform the body.
FIG. 7 shows a slightly modified form of seat member 72. The seat
member 72 has an annular-hub portion 74 which is slightly smaller
in diameter than the seat pocket 76. Similar to the construction of
the seat member 36, the axially outer rear corner 78 of the hub
portion 74 is notched. The corner notch 78 forms with a corner of
the recess a chamber 80 similar to the chamber 54 of the seat
member 36. An O-ring 82 is positioned in the pocket. The seat
member 72 has a flanged portion 84 which extends past the hub
portion 74 and abuts against the front face 86 of the recess.
Instead of having a lubricant groove and the O-ring groove about
the periphery of the hub, there is lubricant groove 88 located in
the flange portion 84 which connects through passages 90 with an
annular lubricant groove 92 on the sealing face 94 of the seat 72.
In order to prevent the lubricant from going directly into the
body, another annular groove 96 is provided outwardly of the
annular lubricant groove 88 and in such groove 96 is positioned an
O-ring 98 which acting together with the O-ring 82 in the chamber
80 provides a lubricant barrier directing the lubricant coming
through a lubricant passage 100 to be directed to the lubricant
groove 92 on the face 94 of the seat. Like the seat member 36, the
seat member 72 is provided with a central passage 102 which aligns
with the bore and forms a part of the bore in the open position.
Also similar to the construction of seat 36, there is adjacent to
the passage an annular groove in which is positioned a deformable
plastic insert 104. The seat member 72 cooperates with a gate 106
in a manner similar to that described for seat member 36.
As can be seen from the foregoing, a valve constructed in
accordance with the present invention has pressure acting seats
whereby a seal will be effected on the upstream side regardless of
which side is upstream. The seats being provided with an annular
plastic insert will easily effect a drop-tight seal; however,
should the sealing faces of the gate or seat become damaged to such
an extent that they will no longer seal, provision has been made to
provide sealant between the faces to effect a seal. The sealant
system is so designed that upon injection of sealant the seat will
move toward maintaining the gap between the two sealing faces at a
minimum.
As various changes may be made in the form, construction and
arrangements of the parts herein without departing from the spirit
and scope of the invention and without sacrificing any of its
advantages, it is to be understood that all matter herein is to be
interpreted as illustrative and not in a limiting sense.
* * * * *