Drilling choke

A fluid flow control valve especially adapted for use during well drilling operations as a drilling choke is disclosed. A replaceable ported seat and movable tubular flow control element cooperate to control flow through the angled body valve housing. The flow closure mechanism is operating fluid pressure balanced for ease of valve operation during extreme pressure working conditions. Internal flow control working parts of the valve are rugged in construction and assemblage. The portions of the valve subject to wear or flow erosion are also easily replaced when required. An indicator is arranged to signal incipient failure of the replaceable parts of the valve in order that they may be replaced prior to the occurrence of a major failure.

TECHNICAL FIELD 
The technical field of the present invention is fluid flow control valves 
and, in particular, drilling choke type valves for controlling drilling 
fluid circulation flow during well drilling operations. 
BACKGROUND ART 
The control of the circulation of drilling fluids during hydrocarbon well 
drilling operations has presented a number of unique flow control 
problems. The presence of the earth cuttings and other highly abrasive 
solids in the drilling fluids have frequently interfered with or damaged 
the valve sufficiently to block operating movement of the flow closure 
elements. The presence in the drilling fluid of corrosive fluids that are 
encountered in the earth formations during drilling has in many instances 
resulted in sufficient corrosion of the valve working parts to render the 
valve ineffective. The valves were also extremely difficult to operate at 
the high working pressures unless a complicated arrangement for balancing 
urging of operating fluid pressure on the movable flow control components 
was provided. In addition, the high operating pressure of the drilling 
fluid often resulted in the restricted or throttled flow eroding or 
cutting the flow control components such as valve seats and can in time 
create a leakage flow path in the valve body itself. 
Many drilling choke valves of rugged and simple construction and design 
have been developed in the past for use during drilling operations. Most 
drilling choke valves have also been made relatively easy to repair or 
otherwise maintain in the field. Despite such ease of maintenance, there 
has remained a need for a drilling choke valve that will indicate a 
failure condition is about to occur in order that preventative-type 
attention will be performed prior to failure. As valve failure would 
ordinarily result in loss of drilling fluid control and could ultimately 
result in loss of the well itself, such an indication of an incipient 
failure condition is a highly desirable valve characteristic or feature. 
A flow control valve for similar usage is disclosed in copending 
application of John D. Muchow and Harry R. Cove, entitled "Valve 
Apparatus", Ser. No. 212,822, filed Dec. 4, 1980, and now abandoned, which 
is also assigned to the assignee of the present invention. 
SUMMARY OF THE PRESENT INVENTION 
The present invention relates to fluid flow control valves that are 
especially well suited for use during drilling operations of hydrocarbon 
wells. The drilling choke valve, which is operating fluid pressure 
balanced for ease of operation, is provided with easily replacable flow 
control components. An indicator is provided for signaling incipient 
failure of the replaceable wear and flow control parts in order that valve 
repairs may be effected prior to the valve being rendered inoperable for 
flow control purposes. 
The preferred embodiment utilizes a right angled valve body or housing 
having flanged end connectors. A bolted bonnet that is easily removed to 
permit access to the valve interior for maintenance and assembly purposes 
is utilized. A flow throttling seat and erosion wear nozzle are secured in 
operating position and sealed to the valve body by the removable bonnet. A 
tubular flow control element is movably positioned within the ported seat 
and mounted on an operating stem that extends through the bonnet. The stem 
is moved by a suitable external actuator to position the flow control 
element relative to the seat to control flow through the valve.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
The valve apparatus of the present invention, generally designated A in the 
Figs., is utilized for controlling flow of fluids through a fluid 
containing conduit (not illustrated) in the usual manner. Preferably, the 
fluid flow control valve apparatus A of the present invention is used in 
controlling the flow of drilling fluids under the severe operating 
conditions usually encountered during earth drilling operations. 
The valve apparatus A includes a valve housing, generally designated H 
formed by a Tee-angled valve body member 10 and valve bonnet 12 which is 
releasably secured thereto in the usual flanged manner by 
equi-circumferentially spaced helically threaded bolting 14 (FIG. 2) 
receiving rotatable securing nuts 16. An O-ring 11 seals between the body 
10 and bonnet 12 to prevent leakage of fluid therebetween in the usual 
manner. The body 10 is preferably of the right-angled Teetype provided 
with a flanged inlet end connection 10a and a corresponding flanged outlet 
end connection 10b for securing with the fluid containing conduit in the 
usual manner. It is, of course, understood that any other known suitable 
end connections may be formed on the valve body 10 without departing from 
the spirit of the present invention. 
The valve body 10 has a fluid flow passage 18 formed therethrough which is 
secured by the end connection flanges 10a and 10b in flow communication 
with the flow conduit in order that the valve body 10 will form a portion 
of the fluid containing conduit. The internal flow passage 18 has a 
regular cylindrical inlet flow portion 18a disposed adjacent the inlet 
flange 10a and a regular cylindrical outlet flow portion 18b disposed 
adjacent the outlet flange 10b. The normal or desired flow direction of 
the fluid is from the inlet passage 18a into the outlet passage 18b which 
are arranged in flow communication and at right angles to each other. The 
longitudinal axes (not illustrated) defined by the cylindrical inlet 
portion 18a and the longitudinal axis of the cylindrical outlet portion 
18b also preferably intersect at right angles to each other. 
Disposed within the outlet portion 18b of the flow passage 18 is a tubular 
erosion control nozzle 20 and a tubular flow control seat 22. The flow 
control seat seal ring 24 engages the seat 22 for securing the seat 22 and 
erosion control nozzle 20 in the outlet portion 18b when the bonnet 12 is 
installed using the bolts 14 and nuts 16. An outwardly projecting collar 
20a of the erosion control nozzle 20 limits movement of the nozzle 20 
through the outlet portion 18b in the usual manner while a central passage 
20b forms the desired path for the outlet flow. An O-ring 21 blocks 
leakage of fluid between the seat 22 and nozzle 20. The upper seal ring 24 
carries alignment and anti-rotation pins 24a and 24b to prevent its 
relative rotational movement with either the seat 22 or bonnet 12, 
respectively. The seal ring 24 also carries O-rings 24c and 24d for 
sealing with the flow closure element 26 and bonnet 12, respectively, to 
control leakage of fluid therebetween. 
Reciprocally disposed within the seat 22 and seal ring 24 is a sleeve or 
tubular flow closure element 26 that is operably connected with the valve 
stem 28 by threads 28a and lock nut 29. The valve stem 28 extends upwardly 
from the flow closure element 26 through a sealed opening 12a formed in 
the removable valve bonnet 12. The stem 28 is used to control the 
operating movement of the flow closure element 26 from exteriorly of the 
valve housing H in the usual manner. In the present instance, the stem 28 
reciprocates the flow closure element 26 within the fixed seat 22 in the 
valve body 10 for controlling flow of fluid through the valve apparatus A. 
The valve seat 22 is provided with a central passage 22a in which the flow 
control element 28 reciprocates and through which the fluid from the inlet 
portion 18a of the flow passage 18 flows into before flowing outwardly 
into passage 20b through the outlet portion 18b of the valve body 10. One 
or more flow throttling ports 22b are formed through the wall of the 
tubular seat member 22 for enabling communication from exteriorly of the 
seat 22 radially inwardly to the central portion 22a where it communicates 
in turn with the outlet portion 18b. Preferably, the ports 22b are 
radially opposed or oppositely positioned on the tubular seat member 22 in 
order that the inwardly flow into the bore 22a will impinge upon 
corresponding flow from the opposite port 22b for minimizing flow 
turbulence and flow cutting or erosion of the seat 22. 
The tubular flow closure element is movable from the first or fully open 
position illustrated in FIG. 1 for enabling flow of fluid through the 
ports 22b to the second or closed position illustrated in FIG. 3 for 
blocking flow through the port 22b. Intermediate these two limit 
positions, the flow closure element 22 partially covers the ports 22b for 
regulating the rate of fluid flow through the valve 22. While a triangular 
port opening 22b is illustrated, it is understood that the shape of the 
ports 22a will determine the flow response operating characteristics of 
the valve 10 and that ports 22a of other shapes may also be employed. 
The erosion control nozzle 20 is secured by the seat 22 and seal ring 24 
engaging the bonnet 12 as described above. The collar 20a formed on the 
erosion control nozzle 20 engages corresponding annular shoulder formed by 
the valve body 10 to provide the lower stop for the erosion control 
nozzle. When secured in the outlet portion 18b, a pair of longitudinally 
spaced seals 30 and 32 effect longitudinally spaced seals between the 
valve body 10 and the erosion control nozzle 20. The spaced seals effected 
by the O-rings 30 and 32 create an operating fluid pressure excluded or 
isolated area between the valve body 10 and the erosion control nozzle 20. 
Should the erosion control nozzle 20 develop a leak such as caused by flow 
erosion or other undesired consequences of the throttled operating fluid 
flow, fluid pressure in the area between the seals 30 and 32 will increase 
to the operating fluid pressure level. The presence of such fluid pressure 
would signal that the erosion control nozzle 20 has failed and that 
erosion damage to the valve body 10 is about to occur from the throttled 
flow. 
The valve body 10 has a leakage port 10c formed therein which communicates 
with the normally fluid pressure isolated area between the O-rings 30 and 
32. Should the operating fluid pressure enter the isolated area, such 
pressure will also be communicated through the leakage port 10c. An 
indicator or signal apparatus generally designated 36 is mounted with the 
valve body 10 by threadedly engaging threads 10d formed in the outer 
portion of the leakage ports 10c. The indicator apparatus 36 includes an 
outer housing member 38 and a closure cap 40 that are secured together by 
threaded engagement at 41. The outer housing 38 and cap 40 form a central 
cavity 42 which is placed in communication with the leakage port 10c and 
isolated area. 
Disposed within the central cavity 42 is a fluid responsive piston 44 and a 
biasing spring 46. The biasing spring 46 urges the fluid piston 44 to the 
normal or inactive position toward the valve body 10. A signal member 48 
is operably associated with the fluid responsive piston and when the fluid 
responsive piston is in the inactive position illustrated in FIG. 1, the 
signal member 48 is substantially retracted within the outer housing 38 
and end cap 40. When operating fluid pressure communicated through the 
leakage ports 10c urges on the fluid responsive piston 44 for effecting 
its movement, the piston will overcome the urging of spring 46 and move 
the signal member 48 to an indicating position extending from the end cap 
40 for providing a signal that the erosion control nozzle 20 is leaking 
and incipient failure condition exists in the valve body. In the 
illustrated embodiment the signal member 48 is provided with a bleed 
closure cap 48a which closes off pneumatic bleed line 50 when moved to the 
extended or indicating position. With the bleed line 50 closed the 
pressure will increase in the bleed line 50 for giving a remote indication 
or signal that incipient failure conditions exist in the valve. 
Removably mounted on the valve bonnet 20 is a valve remote actuator or 
operator, generally designated 60. It is to be understood, however, that a 
manual valve actuator is equally well suited for operation of the valve 
apparatus A. Such a remote valve actuator 60 is well known to those 
skilled in the art and need not be described in extensive detail. In 
general, the actuator 60 is provided with a fluid responsive piston 62 
that is operably connected with the valve stem 28 to effect its 
reciprocating motion and thereby effect the operating movement of the flow 
closure element 26 relative to the flow ports 22 in the usual manner. In 
the illustrated embodiment fluid pressure acting on the lower side 62a of 
the piston 62 will urge the piston 62 to move upwardly. This will move the 
flow closure element 26 upwardly to the open position. Fluid pressure 
introduced above the operating piston 62 will act on the pressure 
responsive surface 62b and will urge the piston 62 and stem 28 with the 
flow closure element 26 downwardly to the closed position for shutting off 
flow through the valve apparatus A in the usual manner. Suitable operating 
condition position indicator mechanism, generally designated 64, may be 
connected with stem extension 28a for providing a remote signal of the 
operating condition of the valve A to ensure that it is properly 
responding to remote commands. 
OPERATION OF THE PRESENT INVENTION 
In the use and operation of the present invention the valve A is assembled 
in the manner indicated and connected in the flow conduit for controlling 
the flow of fluid. Control fluid pressure urging on the actuator piston 62 
will control movement of the valve stem 28 and the connected flow closure 
element 26 to control flow through the port 22b in the usual manner. When 
the flow closure element 26 is in the open or partially open position 
operating fluid flow will pass through the inlet portion 18 and through 
the flow port 22b of the tubular seat 22 into the central cavity 22a. The 
flow is then downwardly through the erosion control nozzle 22 and out of 
the valve A. 
When the operating fluid flow throttled through the flow port 22 erodes or 
otherwise causes leakage of fluid into the isolated area between the seals 
effected by the O-ring 30 and 32 with the erosion control nozzle 20, the 
increased fluid pressure will be communicated through the leakage port 10c 
to the fluid responsive piston 44. Movement of the fluid responsive piston 
44 overcomes the urging of the biasing spring 46 for extending the signal 
member 48 to provide a signal that the incipient failure or leakage 
condition exists. When the remote indicator bleed line 50 is employed, the 
closure 48a will enable pressure build-up in the remote indicator line 50 
to remotely indicate the leakage condition exists at the valve. 
The foregoing disclosure and description of the invention are illustrative 
and explanatory thereof, and various changes in the size, shape and 
materials, as well as in the details of the illustrated construction may 
be made without departing from the spirit of the invention.