Note: Descriptions are shown in the official language in which they were submitted.
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GATE VALVE WITH REPLACEABLE INSERTS AND METHOD
OF REFURBISHING SAME
TECHNICAL FIELD
The present invention relates in general to high-
pressure valves for the oil and gas industry and, in
particular, to gate valves used in severe service
applications in which flow path components of the valve are
subject to wear.
BACKGROUND OF THE INVENTION
Gate valves are used in the oil and gas industry for
heating and treating systems, cementing, fracturing and
acidizing and other well stimulation applications in which
high working pressures and abrasive and/or corrosive fluids
are conducted at high flow rates.
Because a gate valve is subjected to high pressures,
corrosive fluids and abrasive proppants (such as sand,
resin-coated sand or sintered bauxite) the components of
the gate valve that form the flow path through the valve
tend to erode. As is well known in the art, component wear
causes close-fitting components to loose their initial
shape, thereby rendering the gate valve more prone to
leaking. In order to mitigate the effects of wear, gate
valves used in severe service conditions require regular
maintenance and refurbishment. The non-replaceable
components of gate valves are typically refurbished by
welding new metal in the flow path, and then machining the
flow path components back to their original tolerances.
Not only is refurbishment by welding and machining time-
consuming and expensive, but the mechanical and thermal
properties of the weld are inferior to those of the steel
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used to make the gate valve. Furthermore, for sour
service, where welds are exposed to H2S, the welds are
susceptible to sulphide stress corrosion cracking (SSCC).
A further common problem with gate valves is that
abrasive fracturing fluids tend to be drawn into the gate
mechanism when the gate is opened and closed. Attempts
have been made to redress this particular problem by
introducing seals or replaceable liners to inhibit fluid
from entering the gate mechanism, such as, for example, in
U.S. Patent No. 4,051,863 to Still, U.S Patent No.
3,194,259 to Garrod, and U.S. Patent No. 3,624,882 to
Gustafson. Although these prior-art gate valves have seals
or liners to inhibit fluid from penetrating into the gate
mechanism, exposed flow-path components have a propensity
to wear.
Consequently, there exists a need for a gate valve
with improved erosion resistance that is more quickly and
easily refurbished to original specifications.
SUbMARY OF THE INVENTION
It is therefore an object of the invention to provide
a gate valve with improved wear resistance.
It is another object of the invention to provide a
gate valve that is quickly and easily refurbished to
original specifications.
The invention therefore provides a gate valve
including a valve body having a generally cylindrical
passage defining a flow path through the gate valve with a
gate for controlling fluid flow through the flow path, the
gate being translatable in a plane perpendicular to the
flow path between an open position, in which fluid flows
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through the gate, and a closed position, in which fluid
flow is obstructed by the gate, the gate valve having a
replaceable flow path liner comprising: cylindrical valve
seats that protectively line the flow path on respective
sides of the gate, the respective cylindrical valve seats
having an inner end that abuts the gate; wear sleeves that
protectively line the flow path through each valve body
port of the gate valve, the respective wear sleeves having
respective inner ends received in respective outer ends of
the respective cylindrical valve seats; and a cylindrical
gate insert that protectively lines the flow path through
the gate.
The invention further provides a gate valve for use in
severe service applications, the gate valve including a
valve body having a generally cylindrical passage defining
a flow path through the gate valve and a gate for
controlling fluid flow through the gate valve, the gate
being translatable in a plane perpendicular to the flow
path between an open position, in which fluid flows through
the gate valve and the gate, and a closed position, in
which fluid flow is obstructed by the gate, the gate valve
comprising: a replaceable flow-path liner that protectively
lines an entire length of the flow path, comprising:
cylindrical valve seats that protectively line the flow
path on each side of the gate, the respective cylindrical
valve seats having an inner end that abuts the gate; wear
sleeves that protectively line each valve body port of the
valve body, the respective wear sleeves having respective
inner ends received in respective outer ends of the
respective valve seats; and a cylindrical gate insert that
lines the flow path through the gate and is retained in the
flow path through the gate by a mechanical fastener.
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The invention yet further provides a method of
refurbishing a gate valve comprising: disassembling the
gate valve; removing a replaceable flow-path liner that
lines an entire length of the flow path, the flow path
liner comprising contiguous inserts, including:
cylindrical valve seats that protectively line the valve
body on respective sides of a gate of the gate valve, the
respective cylindrical valve seats having respective inner
ends that abut the gate; wear sleeves that protectively
line respective valve body ports on opposed sides of the
valve body, the respective wear sleeves having an inner end
received in respective outer ends of the respective
cylindrical valve seats; and, a cylindrical gate insert
that protectively lines the flow path through the gate and
is retained in the flow path through the gate; inspecting
the flow-path liner inserts; replacing any worn flow-path
liner inserts; and reassembling the gate valve by inserting
the respective cylindrical valve seats in the valve body on
respective sides of the gate; inserting an inner end of the
wear sleeves that protectively line respective valve body
ports into respective outer ends of the respective
cylindrical valve seats; and, inserting the cylindrical
gate insert into the gate.
The invention also provides a gate valve that includes
a valve body with a generally cylindrical passage defining
a flow path through the valve body and a pair of opposed
flanged ports on opposed sides of the valve body,
comprising: cylindrical valve seats that protectively line
the flow path through the valve body on respective sides of
a gate for controlling flow through the gate valve, the
respective cylindrical valve seats having an inner end that
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abuts the gate; wear sleeves that protectively line the
flow path through each of the respective valve body ports,
the respective wear sleeves having respective inner ends
received in respective outer ends of the respective
cylindrical valve seats; and a cylindrical gate insert that
protectively lines a flow path through the gate.
The invention yet further provides a gate valve,
comprising: a valve body with a generally cylindrical
passage defining a flow path through the valve body; a
pair of opposed flanged ports on opposed sides of the valve
body, the flow path extending through the respective
flanged ports; cylindrical valve seats that protectively
line the flow path through the valve body on respective
sides of a gate for controlling flow through the gate
valve, the respective cylindrical valve seats having an
inner end that abuts the gate; wear sleeves that
protectively line the flow path through each of the
respective valve body ports, the respective wear sleeves
having respective inner ends received in respective outer
ends of the respective cylindrical valve seats; and a
cylindrical gate insert that protectively lines a flow path
through the gate.
BRIEF DESCRIPTION OF THE DRAWINGS
Further features and advantages of the present
invention will become apparent from the following detailed
description, taken in combination with the appended
drawings, in which:
FIG. 1 is an exploded view of a gate valve in
accordance with an embodiment of the invention;
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FIG. 2 is a perspective view of the fully assembled
gate valve in accordance with the embodiment shown in FIG.
1;
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FIG. 3 is a perspective view of the gate valve shown
in FIG. 1, illustrating the gate mechanism and replaceable
inserts removed from the valve body, flange and cap;
FIG. 4 is a perspective view of the gate valve shown
in FIG. 1, illustrating the valve body removed to show the
gate in the open position;
FIG. 5 is a perspective view of the gate valve shown
in FIG. 1, illustrating the valve body removed to show the
gate in the closed position;
FIG. 6 is a perspective view of a replaceable valve
seat with a wiper ring in accordance with another
embodiment of the invention
FIG. 7 is a perspective view of a replaceable valve
seat with a wiper ring arld a retainer ring in accordance
with a further embodiment of the invention; and
FIG. 8 is a perspective view of an assembled gate
valve in accordance with the invention equipped with a
replaceable insert used for interconnecting the gate valve
with another gate valve or plug valve, a fracturing head, a
wellhead isolation tool or any other component in a
pressure control stack used for well stimulation
operations.
It will be noted that throughout the appended
drawings, like features are identified by like reference
numerals.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
The invention provides a gate valve that includes a
valve body having a cylindrical passage defining a flow
path through the valve, a gate for controlling fluid flow
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through the valve with a replaceable wear-resistant flow-
path liner for protectively lining the flow path through
the valve. The flow-path liner includes a plurality of
replaceable wear-resistant inserts, e.g. replaceable wear
sleeves for protectively lining ports of the valve body,
replaceable valve seats for lining the valve body and a
replaceable gate insert for a flow path bore through the
gate. By regularly inspecting and replacing worn inserts,
a service life of the gate valve can be significantly
prolonged, thus obviating a considerable expense associated
with replacing or rebuilding the valve body.
FIGS. 1 and 2 are exploded and assembled views,
respectively, of a gate valve, generally indicated by the
reference numeral 10, in accordance with an embodiment of
the invention. The gate valve 10 includes a valve body 12,
which is the most expensive component of the gate valve.
The valve body 12 has a generally cylindrical passage
defining a flow path 14 through the valve. The flow path
14 extends between a pair of opposed flanged ports 16. The
valve body 12 also has a gate housing 18 which is a tubular
structure transverse to the flow path 14. The gate housing
18 includes a large cavity 19 in which a gate mechanism 20
is housed. The gate mechanism 20 is encased by a flange
34, which is connected by threaded fasteners to the gate
housing 18, and also by a cap 36, which is mounted to the
flange.
As shown in FIGS. 1 and 3, the gate mechanism 20
includes a gate 22 having a flow path bore 24 that forms
part of the flow path when the gate is in an open position.
The gate can be moved in a plane perpendicular to the flow
path between an open position, in which fluid flows through
the valve, and a closed position, in which fluid flow is
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obstructed using a valve control wheel 32. The gate 22
also includes a rectangular slot 26 into which a gate
control block 28 is received. Mounted to the gate control
block 28 is a sleeve 29 for receiving a stem 30. The stem
is connected to valve control wheel 32, or other such
mechanism for applying torque to the stem. Torque applied
to the valve control wheel causes the stem to rotate.
Rotation of the stem is converted into movement of the
gate, i.e., moving the gate from an opened to a closed
position, or vice versa, in a manner well known in the art.
As shown in FIG. 1, the gate valve 10 includes a
replaceable flow-path liner 40 protectively lining the flow
path 14. In the illustrated embodiment, the replaceable
flow-path liner 40 extends throughout an entire length of
the flow path 14, although persons of ordinary skill in the
art will appreciate that the replaceable flow-path liner 40
could be extended over only a portion of the flow path 14
to protect a selected portion of the flow path most
susceptible to wear.
As shown in FIG. 1, the replaceable flow-path liner 40
includes five replaceable, contiguous wear-resistant
inserts. The replaceable inserts include a replaceable
gate insert 42 for protectively lining the flow path bore
24 in the gate 22; a pair of replaceable wear sleeves 44
for protectively lining the ports 16 of the valve body 12;
and a pair of replaceable valve seats 46 for protectively
lining the flow path between the gate insert 42 and the
wear sleeves 44.
As shown in FIGS. 1 and 3, the gate 22 further
includes a pair of bores 43 that are orthogonal to the flow
path 14. The bores 43 receive mechanical fasteners, such
as set screws (not illustrated). The mechanical fasteners
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secure the replaceable gate insert 42 within the flow path
bore 24 through the gate 22.
As shown in FIG. 3, the replaceable valve seats 46
receive an inner end of the replaceable wear sleeves 44 at
an outer end and are in abutment with the surfaces of the
gate 22 at an inner end. In another embodiment of the wear
inserts, the wear sleeves 44 pass substantially through the
valve seats 46. 0-rings 47 provide a fluid seal between the
inner end of the valve seats 46 and the valve body 12.
Likewise, o-rings 49 provide a fluid seal between the
replaceable wear sleeves 44 and valve body ports 16.
FIG. 4 shows the replaceable valve seats 46 aligned
with the flow path 14 in the open position in which fluid
is free to flow through the bore 24 in the gate 22. For the
sake of illustration, the valve body 12 is shown removed in
both FIG. 4 and FIG. 5. The gate 22 is shown in the closed
position in FIG. 5, as the valve seats 46 are offset with
respect to the flow path 14. The flow path 14 is
obstructed by the solid upper portion of the gate 22.
As shown in FIGS. 6 and 7, each replaceable valve seat
46 includes a wiper ring 50. When the gate 22 is opened or
closed, the wiper ring 50 wipes the gate, thereby cleaning
the gate of fluids, proppants or other debris that would
otherwise be drawn into, and potentially clog, the gate
mechanism 20.
As shown in FIG. 6, the replaceable valve seats 46 may
include an annular groove 48 for receiving the wiper ring
50. The wiper ring 50 can be made of rubber, polyurethane
or any other material that is suitable for cleaning the
surfaces of the gate.
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A further embodiment of the valve seat 46 is shown in
FIG. 7 in which the valve seat includes an annular shoulder
52 for receiving the wiper ring 50. The wiper ring 50 is
surrounded and retained in place by a retainer ring 54.
The retainer ring 54 can be made of brass, bronze,
stainless steel or other suitable material.
In one embodiment, the gate insert 42 may be made of
4340 steel. For sour well service, the gate insert can be
made of 17-4 stainless steel. The replaceable wear sleeves
44 may be made of 4340 steel or 8620 case hardened steel.
For sour well service, the replaceable wear sleeves can be
17-4 stainless steel. The valve seats 46 in one embodiment
are 4140 steel, although they may likewise be made of 4340
steel or 8620 case hardened steel. The valve body, flange,
cap are made of AISI 4130 or 4140 steel. The valve gate
can be made of 17-4 stainless steel to permit the gate
valve 10 to be used for sour service applications.
The service life of this gate valve 10 can be
prolonged significantly by replacing the wear-resistant
inserts at regular maintenance intervals. The gate valve
can be disassembled and the various inserts inspected and
replaced as required to return the gate valve 10 to its
initial specifications. Due to the advantageous design of
this gate valve, worn inserts can be quickly and easily
replaced. The replaceable inserts therefore obviate the
need to rebuild or replace the expensive valve body 12 or
other valve components including the valve gate 22.
FIG. 8 is a side perspective view from the side of a
gate valve 10 in accordance with the invention equipped
with a wear-resistant replaceable sleeve 44a in accordance
with another aspect of the invention. The wear-resistant
replaceable sleeve 44a is longer than the port 16 in which
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it is inserted. The inserted end of the wear sleeve 44a is
configured in the same way as the wear sleeve 44 shown in
FIGs. 1 and 3-5. The free end of wear sleeve 44a permits a
seamless connection between the gate valve 10 and any other
pressure control element equipped with wear-resistant flow
path inserts in a pressure control stack. For example, a
connection between the gate valve 10 and a plug valve with
wear-resistant inserts as described in applicant's co-
pending Canadian Patent Application No. 2,476,813 entitled
HIGH PRESSURE PLUG VALVE WITH REPLACEABLE INSERTS AND
METHOD OF REFURBISHING SAME, filed August 6, 2004, or a
connection between the gate valve and a fracturing head
with wear-resistant inserts described in Applicant's co-
pending Canadian Patent Application No. 2,486,513 entitled
FRACTURING HEAD WITH REPLACEABLE INSERTS FOR IMPROVED WEAR
RESISTANCE AND METHOD OF REFURBISHING SAME filed on
November 1, 2004.
The seamless connection enabled by the replaceable
wear-resistant sleeve 44a prevents erosion at the flanged
connection of two elements in a pressure control stack. The
length of the wear sleeve 44a depends on the element to
which the gate valve 10 is to be connected. The free end of
the replaceable wear-resistant sleeve cooperates with
another wear-resistant insert in the other element in the
flow control stack to provide the seamless connection
between the gate valve 10 and the other element. A fluid
seal is provided on the free end of the wear sleeve by an
0-ring 49a. Alternatively or in addition, a fluid seal can
be provided by ring gaskets 52 and flange gaskets 50.
Providing a seamless connection between elements in the
flow control stack prolongs the life of replaceable wear-
resistant sleeves used to line the respective flow paths at
the connection, and also ensures that there is no washout
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damage to ports of the interconnected elements. Washout at
flanged connections tends to become a problem at high
volume pump rates.
Persons of ordinary skill in the art will appreciate,
in light of this specification, that minor variations may
be made to the components of the gate valve without
departing from the sprit and scope of the invention. The
embodiments of the invention described above are therefore
intended to be exemplary only and the scope of the
invention is limited only by the scope of the appended
claims.
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