FIELD OF INVENTION
The invention relates to Full Bore or Through conduit Gate Valves used in Oil
Field Equipment, particularly in Wellhead and X-Mas Tree configuration,
manifolds, flow lines of offshore installations to open and shut the flow of
produced oil and gas medium. In particular, the invention relates to an improved
full bore gate valve having full metal to metal sealing capability. More
particularly, the invention relates to a parallel solid gate valve adaptable to the
wellhead and X-Mas Tree.
BACKGROUND OF THE INVENTION
Full Bore Valves of the existing art have following seals in flow path:
1) Seat to Body seal
2) Seat to Gate seal
In Full Gate Valves, usually the Seat to Gate seal is a metal to metal seal. And
Seat to Body seal is normally an elastomeric one. Elastomeric seals tend to get
extruded, when used over a period with high velocity gas medium. Also
Elastomeric seals will loose its properties when the temperature of medium
increases.
In order to eliminate the disadvantages of prior art elastomeric seals, in some of
the existing designs, a metallic spring is introduced at the upstream side
between the valve body and the seat so that compression of the metallic spring
will generate adequate contact pressure to ensure positive downstream sealing
between the seat and the body at low pressures. However, since the spring is to
be at upstream side of the valve, the valve is to be installed in that position.
Hence the valve can not be called as bi-directional.
Another practice is to lap the entire Seat and the Body contact surface to a
'smooth finish to effect the sealing. However, this process is time consuming and
st prohibitive for mass production.
US Patent 4,264,054 discloses a Metal to metal seat hub seal adaptable to Parallel
Expanding Gate valves. In Parallel Expanding Gate valves, the valve seats are
fixedly mounted in the valve body. The gate of such a valve assembly is formed in
multiple parts which, when the valve is closed or opened, expands longitudinally
against the valve seats to form tight seals. In this invention, a metal gasket
deforms and seals the annular space between the seat and the body due to the
interference during assembly of the Seat and the Gate. In Parallel Expanding Gate
valves, sealing is effected by the interference between the Seat and the Gate at
the open or closed position of the valve. The interference / wedging action
between the Seats and the Gate result in increased operating torque which results
in seizure/ damage to the Seat Ring and the Gate sealing surfaces. Hence in
some designs, Teflon inserts are introduced in between the Gate and the Seat ring
faces, which makes the design non-metallic.
Due to the described disadvantages of the existing Parallel Expanding Gate valves,
industry preference is for Parallel Solid Gate Valve design, where there is no
interference between the Gate and the Seats. The invention described in above
patent will not work in Parallel Solid Gate Valves (where there is no interference
between Gate and Seats).
In Wellhead and X-Mas Tree configuration, Manifolds and flow lines in offshore
platforms, Full Bore Gate valves are used to open and shut the flow of produced
oil/gas medium. Full Bore or Through conduit gate valves, which when opened
present an unbroken smooth wall conduit for uninterrupted passage of flow there
through.
A gate valve assembly typically includes a valve body defining a longitudinal flow
"passage and a valve element called Gate mounted in the valve body being
vable transverse to the flow passage. In through-conduit gate valves, the valve
element, or gate, has a solid portion of sufficient dimension to block off and close
the flow way when it is aligned therewith. The gate also includes a bore or port
(of same diameter as the flow passage) oriented parallel to the flow passage. By
moving the gate in the aforementioned direction, the solid portion thereof can be
displaced from the alignment with the flow way, and the port moved into the
alignment with the flow way to open the valve. Such valves also typically include
annular valve seats mounted in the valve body, coaxially with the flow passage,
on opposite sides of the gate, for a sealing engagement with the latter.
One of the advantages of the through-conduit gate valve assemblies for oil field
use, is that there is no obstruction to the flow way when the valve is in open
position. Also the gate periodically wipes the sealing faces of the seats when it is
caused to move between its open and closed positions, and even when in the
open position, the gate remains in contact with the sealing areas of the seats,
thereby protects the sealing surfaces of the Gate.
In prior art Parallel Expanding Gate valves, at the open or closed position, Gate
segments wedge against each other to have interference between the Gate, the
Seat and the valve body cavity. And sealing is effected by the interference
between the Seat and the Gate at the open or closed position of the valve. In
Parallel Solid Gate Valves, seats are permitted limited axial play with respect to
the valve body and the Gate, and it is by virtue of such movement that they effect
a Gate to Seat sealing. Present invention is incorporated on a Parallel Solid Gate
valve to introduce metal to metal seal between the Seat and the Body.
OBJECTS OF THE INVENTION
It is therefore an object of the invention to propose a parallel-solid Gate Valve, in
which the Seat to Body sealing and the Gate to Seat sealing is fully metallic.
Another object of the invention is to propose a parallel-solid gate valve which
eliminates elastomeric seals from the main sealing elements.
A further object of the invention is to propose a parallel-solid Gate valve in which
elastomeric seals act as supplementary seal or back-up to metal seal.
A still further object of the invention is to propose a parallel-solid Gate valve
which eliminates the need for lapping the entire face of Seat Ring rear face.
Yet another object of the invention is to propose a parallel-solid Gate valve which
provides initial contact pressure between the Gate and the Seal Ring at low
pressures.
A still another object of the invention is to propose a parallel-solid Gate valve
which retains Bi-directional feature of the valve.
Further objective and advantages of this invention will be more apparent from
the ensuing description when read in conjunction with the accompanying
drawing.
SUMMARY OF INVENTION
Accordingly, there is provided a parallel solid Gate valve for the wellhead and X-
Mass tree of the offshore platforms extracting liquid petrolium, the valve
comprising a parallel solid Gate valve adaptable to the wellhead and X-Mass tree
of the offshore platforms extracting liquid petrolium, the valve comprising a valve
body having a flow passage; a cylindrical valve chamber having a vertical axis
formed in said valve body and intersecting said flow passage to define at least
one each diametrically opposed inlet and outlet openings in said chamber, said
flow passage having a portion of slightly enlarged diameter at the position of
said openings; a pair of valve seats one each for body sealing and gate sealing,
each valve seat having two different cylindrical outside diameters, one larger
than the other, the smaller outside diameter of each of the said valve seat
installed within said enlarged portion of said valve passage, said valve seat
further having a bore extending therethrough, being coaxial, and the bore
constituting extensions of said flow passage; a gate interposed between the
valve seats and at least one flat face of said gate for sealing the corresponding
flat faces of said seats, a bore of the gate coaxial and in communication with the
flow passage when in full open position, the Gate bore can be disabled for
communication with said bore of the valve seats when in closed position; the
valve seat comprises one each upstream seat ring and downstream seat ring,
and in that the flat of the seat ring, halves each face provided wit a double bump
profile which enables leak proof sealing of a cavity face of the valve body and
the face of the seat ring.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWING
Figure-1 cross sectional elevation of the valve of the present invention, in open
position.
Fig.2 is cross sectional elevation of the valve of the present invention, in closed
position.
DETAILED DESCRIPTION OF A PREFFERED EMBODIMENT OF THE
INVENTION
A description will first be given with reference to Fig.l and 2. In figure, reference
numeral 1 represents the valve body. A pair of Seat Rings (2) (which are having
Double Bump profile (19) at the rear face) are located in valve body cavity seat
pocket area (11). The Valve body (1) is having the flow passage bore (14). A
cylindrical valve chamber (22) having a vertical axis (23) is formed in the valve
body (1) and intersects the flow passage (14) to have diametrically opposite inlet
and outlet.
The valve body (1) may be provided with flanged or threaded end connections
(not shown in figure) to facilitate suitable connections. The Cylindrical valve body
chamber (22) has enlarged diameters at top and also in a seat pocket area (11). A
pair of identical valve seats (2) are installed in the valve body seat pocket opening
(11) which is having slightly enlarged diameter than the flow passage (14). Each
valve seat (2) has two cylindrical outside diameters - one larger than the other.
Smaller outside diameter of each of said valve seat (2) is installed within an
enlarged portion of said valve passage (14) at one of said openings (11). Rear
face of larger outside diameter (21) of seat (2) compresses a metal spring (3)
(located in the valve body cavity groove 10). The Metal spring (3) ensures
sufficient initial contact pressure between the sealing surfaces of the Gate (5) and
seat (2) at low pressures. The bore (15) of the valve seat (2) is coaxial with the
flow passage bore (14) and forms an extension of said flow passages. An O-Ring
(4) is located at the groove (12) of the seat ring.
The O-Ring (4) can seal the annular space between the body and the seat (2) and
ves as a back-up seal to the metal to metal seal between the Double bump
profile (19) of the seat (2) and face (18) of the valve body cavity. Metal to metal
sealing feature is explained in detail under the title 'Description of Valve
Operation'.
Gate (5) is located in between the Seat Rings (2) and planar faces of said Gate (5)
seals against planar faces of said seats (2). Planar surfaces are hard faced with
stellite and ground and lapped for effective sealing. The Bore (16) of_ gate (5) is
coaxial with the flow passage (14) and the seat bore (15) in full open position of
the valve. Sides of the Gate (not shown in figure) can guide along the cylindrical
valve chamber (22). A Gate Nut hole (14) near top portion of the Gate (5) is
provided parallel to the bore (16) of the Gate (5). The Gate (5) also has a vertical
hole (24) which locates bottom portion of Stem (7). The Gate Nut (6) is inserted
in Gate Nut hole (14) and the Gate Nut (6) is threaded (numeral 13 shows
threaded surface) to the Stem (7). As the Stem (7) is rotated, the Gate Nut (6)
together with the Gate (5) can slide vertically between the planar surfaces of the
Seat Rings (2).
Fig.l shows the valve in open position. As the stem (7) is rotated in clockwise
direction, the Gate Nut (6) together with the Gate (5) travels downwards till the
bottom of the Gate touches the bottom of the cylindrical body cavity (25) as
shown in Fig.2. At this position, the valve is closed. Soild stellite hardfaced
surface (20) of the Gate (5) blocks the flow passage and the Bore (16) of the
gate (5) is not communicating with the bore (15) of the valve seats (2) in closed
position.
DESCRIPTION OF VALVE OPERATION
A brief description will now be given for the operation of the valve as shown in
Fig.l. The valve is shown in open position. The flow passage bore (14), the bore
(15) of the seat (2) and the bore (16) of the gate (2) are aligned and the flow
path of fluid is in the shape of a through conduit.
At this position, fluid enters through valve inlet and fluid pressure acts through
upstream Seat Ring hub area (17). Fluid pressure acting at the Seat hub area (17)
pushes the upstream Seat Ring (2a), the Gate (5) and the down stream Seat Ring
(2b) towards the valve body cavity face (18). The Double bump profile (19) of the
Down stream Seat Ring (2b) will effect the sealing with the valve body cavity (18).
At closed position of the Gate, the Solid Stellited surface (20) of the Gate (5)
blocks the flow passage as shown in Fig.2. Fluid entering through valve inlet acts
through the upstream Seat Ring hub area (17) and also at the solid surface (20)
of the Gate (5). Fluid pressure acting at the Seat hub area (17) combined with the
fluid pressure acting at solid surface (20) of Gate (5) pushes the upstream Seat
Ring (2a), the Gate (5) and down the stream Seat Ring (2b) towards the valve
body cavity face (18). The Double bump profile (19) of the Down stream Seat
Ring (2b) will effect the sealing with the valve body cavity (18).
WE CLAIM
1. A parallel solid Gate valve for the wellhead and X-Mass tree of offshore
platforms extracting liquid petroleum from sea-bed, the valve comprising:-
• a valve body (1) having a flow passage (14);
• a cylindrical valve chamber (22) having a vertical axis (23) formed in said
valve body (1) and intersecting said flow passage (14) to define at least
one each diametrically opposed inlet and outlet openings (11) in said
chamber (22), said flow passage (14) having a portion with slightly
enlarged diameter at the position of said openings (11);
• a pair of valve seats (2a,2b) one each for body sealing and gate sealing,
each valve seat (2a,2b) having two different cylindrical outside diameters,
one larger than the other, the smaller outside diameter of each of the said
valve seat (2) installed within said enlarged portion (11) of said valve
passage (14), said valve seat (2) further having a bore (15) extending
therethrough, being coaxial, and the bore (15) constituting extensions of
said flow passage (14);
• a gate (5) interposed between the valve seats (2a,2b) and at least one
planar face of said gate (5) for sealing the corresponding planar faces of
said seats (2a,2b), a bore (16) of the gate (5) coaxial and in
communication with the flow passage (14) when in full open position, the
Gate bore (16) can be disabled for communication with said bore (15) of
the valve seats (2) when in closed position;
characterized in that the valve seat (2) comprises one each upstream seat
ring (2a) and downstream seat ring (2b), and configured such as to
permit a limited axial play with respect to the valve body (1), and in that
the flat face of the seat ring halves (2a,2b) each provided with a double
bump profile (19) which enables leak proof sealing of a cavity face (18) of
the valve body (1) and the face of the seat ring (2).
2. The gate valve as claimed in claim 1, comprising at least one metal Spring
(3) disposed in a cavity groove (10) of the valve body (1).
3. The Gate valve as claimed in claim 1 or 2, wherein the gate (5) comprises
a solid surface (20), wherein the valve seat (2) comprises a seat hub area
(17), and wherein the fluid through the inlet generates a fluid pressure on
both the solid surface (20) and the seat hub area (17), the fluid pressure
pushing the upstream seat ring (2a), the gate (5), and the downstream
seat ring (2b) towards the cavity face (18).
4. The Gate valve as claimed in claim 1, wherein the Gate (5) further
comprising one each gate nut hole (14) and vertical hole (24), and a
threaded gate Nut (6) which is threaded to a Stem (7) of the valve, the
gate nut (6) together with the gate (5) being vertically slidable between
the flat surfaces of the valve seat (2) on rotation of the stem (7).

The invention relates to a parallel solid Gate valve for the wellhead and X-Mass
tree of offshore platforms extracting liquid petroleum from sea-bed, the valve
comprising a valve body (1) having a flow passage (14); a cylindrical valve
chamber (22) having a vertical axis (23) formed in said valve body (1) and
intersecting said flow passage (14) to define at least one each diametrically
opposed inlet and outlet openings (11) in said chamber (22), said flow passage
(14) having a portion with slightly enlarged diameter at the position of said
openings (11); a pair of valve seats (2a,2b) one each for body sealing and gate
sealing, each valve seat (2a,2b) having two different cylindrical outside
diameters, one larger than the other, the smaller outside diameter of each of the
said valve seat (2) installed within said enlarged portion (11) of said valve
passage (14), said valve seat (2) further having a bore (15) extending
therethrough, being coaxial, and the bore (15) constituting extensions of said
flow passage (14); a gate (5) interposed between the valve seats (2a,2b) and at
least one planar face of said gate (5) for sealing the corresponding planar faces
of said seats (2a,2b), a bore (16) of the gate (5) coaxial and in communication
with the flow passage (14) when in full open position, the Gate bore (16) can be
disabled for communication with said bore (15) of the valve seats (2) when in
closed position; the valve seat (2) comprises one each upstream seat ring (2a)
and downstream seat ring (2b), and in that the flat face of the seat ring halves
(2a, 2b) each provided with a double bump profile (19) which enables leak proof
sealing of a cavity face (18) of the valve body (1) and the face of the seat ring
(2).