Note: Descriptions are shown in the official language in which they were submitted.
116~84~
FIRE~SAFE VA~VE ACTUATOR
F D OF THE IN~ENTION
This invention relates generally to valve actuator
systems and, more particularly, concerns a valve actuator
that is capable of providing protection for the bonnet
structure of a valve during conditions of extreme heat,
such as by external fires, thereby preventing heat induced
deterioration of the pressure containing integrity of the
valve mechanism for extended periods of time. Even more
specifically, the present invention relates to a valve ac-
tuator mechanism that may be simply and efficiently re-
paired or replaced while the valve serviced thereby is
allowed to be maintained under pressure during removal of
the actuator from the valve mechanism.
BACKGROUND OF THE INVENTION
When the bonnet structure of a conventional high pres-
sure gate valve is assembled to the valve body, the bolts
or studs and nuts that interconnect the body and bonnet
structures are typically stressed quite highly in order to
prevent leakage at the bonnet joint during periods when
the valve is pressurized to its maximum operating pres-
sure. Moreover, when the valve body is pressurized, these
studs and nuts and bolts are subjected to considerable
stress due to pressure acting on the seal area of the
bonnet-to-body connection. In the event of a severe fire
in close proximity to the valve and actuator mechanism,
the studs and nuts or bolts that secure the bonnet to the
val~e body will become heated quite rapidly. In many
cases, valve failure occurs during the excessive heat of
direct flame impingement because the studs and nuts become
heated to a temperature that reduces the strength thereof
1 lB~844
to the failure point. In many cases, it is desirable that
valves be designed to remain safe and operative for ex-
tended periods of time even under circumstances where di-
rect flame impingement causes rapid heating thereof. It
is desirable, therefore, to prolong the time required for
the studs and nuts of a bonnet-to-body connection to reach
a temperature that reduces the strength of the studs and
nuts to a level where failure occurs and the bonnet seal
is lost. By prolonging the typical failure time of con-
1~ ventional valves, it is possible for the external fire tobe extinguished before any high pressure valves can become
heated to the point that stud and nut failure occurs. Ob-
viously, in the case of combustible materials, such as pe-
troleum products, it is highly desirable that fire induced
valve failure be retarded in order to prevent the high
pressure petroleum products from leaking from the bonnet
connection and feeding the fire.
Another typical cause of valve failure induced by the
heat of external fires is the failure of the stem packing
structure of the valve which ordinarily prevents internal
valve pressure frnm escaping from the valve stem opening
of the bonnet. Under circumstances of excessive heat,
typical stem packing materials deteriorate quite rapidly
and tend to allow stem leakage. It is desirable, there-
fore, to provide a valve and valve actuator mechanism hav-
ing the capability of retarding transfer of the heat of an
external fire to the valve stem packing and thereby retard
any valve stem leakage that might otherwise occur. It is
also desirable to provide the packing structure of the
3~ valve with means to promote introduction of a combination
lubricant and sealant material by way of an exposed lubri-
cation fitting even though the valve and valve actuator
1 164844
mechanism may be designed for retarding transfer of heat
to the bonnet structure of the valve.
In many cases, pneumatic valve actuators are employe"d
incGrporating spring return features that induce mechani-
cal movement of a valve stem to a predetermined positionin opposition to the direction of movement induced by a
pneumatic diaphragm controlled system. One of the prob-
lems with spring return of pneumatic diaphragms, however,
is the degree of rotary force t~ which the diaphragm is
often subjected as the compression spring winds and un-
winds during compression and extension thereof during lin-
ear movement of the valve stem. In many cases it is also
desirable to prevent introduction of rotational forces to
the valve stem as well. It is desirable, therefore, to
provide a valve actuator mechanism incorporating means to
protect the diaphragm of the pneumatic actuator from
spring-induced rotational forces during actuation thereof.
In some types of diaphragm type actuators~ an actuator
stem is threaded to the valve stem so that upon rotation
2û of the actuator stem (e.g., manually), the valve stem is
moved axially to open or close the valve. In such instan-
ces, it is desirable to minimize the torque applied to the
diaphragm by the rotating actuator stem.
One of the serious disadvantages of pneumatic actua-
~5 tors, as well as many other types of valve actuators, isthe inability of the valve actuators to be repaired and/or
replaced while the valve associated therewith remains un-
der pressure. Under circumstances where it is simply nec-
essary to replace the diaphragm of a diaphragm type pneu-
matic actuator, it is frequently necessary to shut downthe entire production line and ~eplete the pressure of the
116~844
valve controlled by the actuator befcre the actuator can
be disassembled for replacement or repair~ It is desira-
ble, therefore, to provide a pneumatic valve actuator
mechanism that may be simply and efficiently removed for
replacement or repair without necessitating complete shut-
down and depressurization of the flow system that is con-
trolled by the valve.
SUMMARY OF THE INVENTION
It is therefore a feature of the present invention to
provide a novel valve actuator system that has the capa-
bility of providing a bolted bonnet type valve mechanism
with protection against deterioration of the bolt and
studs thereof by direct impingement of external fires on
the valve ~nd actuator assembly.
It ls also a feature of this invention to provide a
novel valve and actuator assembly wherein the stud and nut
bonnet connection structures of the valve are encapsulated
within a protective chamber and are insulated in order to
retard transfer of the heat of external fires to the studs
and nuts of the valve bonnet assembly.
It is an even further feature of this invention to
provide a novel valve and actuator assembly wherein the
stem seal structure of the valve mechanism is efficiently
protected against the heat of external fires in order to
retard transfer of heat to the stem packing structure of
the bonnet and therefore retard the development of any
heat induced stem leakage t~hat might otherwise occur.
Among the several features of this invcntion is con-
templated the provision of a novel pneumatic valve actua-
3û tor mechanism that incorporates means to prevent transferof rotary spring induced force to the diaphragm of the
valve actuator and thereby prevent diaphragm deterioration
1 16~4
that might otherwise be induced by winding an~ unwinding
of the compression spring as it collapses and extends dur-
ing linear movement of the valve stem.
It is also an important feature of this invention to
pro~ride a novel-valve actuator mechanism that may be sim-
ply and efficiently removed from a valve and bonnet assem-
bly while at the same time allowing the valve mechanism to
be maintained under pressure and in safe condition.
In accordance with another feature of this invention,
10 - provision is made for efficient introduction of sealant
material into the valve packing assembly even though the
bonnet structure of the valve is encapsul2ted for the pur-
pose of fire protection.
The present invention is directed to the provision of
a pneumatic valve actuator for a valve wherein the primary
force for causing the valve stem to move outwardly is de-
veloped by line pressure in 'he valve acting in the cross-
sectional area of the stem. A compression spring is also
provided to apply a secondary force to the stem to assure
its outward movement when line pressure is low or absent.
The stem is moved inwardly by pressure applied to a dia-
phragm connected to the stem. The compression spring
bears against a spring plate that is interconnected with
the valve stem by means of a bearing structure. The bear-
ing structure reduces or eliminates torque from being ap-
plied to the stem and hence possibly to the diaphragm by
winding and unwinding of the spring as it compresses and
extends.
A diaphragm element is secured to a diaphragm plate
that is also interconnected with the valve stem by means
of a bearing structure. Rotational movement induced by
rotatin9 the stem is preventing from being transmitted to
--5--
1 164~44
the diaphragm plate by the bearing mechanism. Thus, the
diaphragm and valve stem are not subjected to rotational
stresses as the actuator mechanism imparts operative move-
ment to the valve stem in either direction thereof.
The unique relationship of the spring plate and dia-
phragm plate to the valve stem allows the actuator mecha-
nism, with exception of the compression spring and spring
plate assembly, to be simply and efficiently removed from
the valve for repair or replacement. Removal of the actu-
ator housing is accomplished simply by removing a minimum
number of connection bolts that secure the actuator hous-
ing to the bonnet structure and by simply moving the actu-
ator housing away from the valve to cause the desired sep-
aration. When the valve actuator is removed, the spring
and spring plate remain in assembly with the valve stem.
The compression return spring, therefore, continuously en-
ergizes the valve stem through the spring plate and main-
tains the valve stem at an outwardly extended position.
This outwardly extended position of the valve stem may be
a safe "open" or safe "closed" position, depending upon
the location of the port in the gate. In most cases, how-
ever, the safe position of the valve is the closed posi-
tion.
Under circumstances where the valve must be place~
back on stream as rapidly as possible, a replacement actu-
ator may be provided and may be simply and efficiently in-
stalled simply by moving the housing thereof onto the
valve stem and bringing the diaphragm plate and bearing
assembly into engagement with an appropriate shoulder de-
fined on the valve stem. The replacement actuator may besimply bolted into assembly with the valve bonnet struc-
ture and the appropriate pneumatic connections may be made
-6-
8 ~ 4
to complete the installation operation. q~he valve bonnet
is formed to define an annular actuator support flange that
is positioned in spaced relation with a typical bonnet flange
that: is designed for attachment to a valve body by means of studs
S and nuts. The actuator housing is formed to define an elongated
connection portion or shroud that encircles the actuator con-
nection flange and the bonnet flange. The actuator shroud
cooperates with the bonnet structure to define an annular
protective chamber within which the studs and nuts are
located. This protective chamber may also be filled with a fire
retardant heat insulation material that assists in protecting
the studs and nuts from transfer of heat. Thus, the studs and
nuts of the bonnet structure are protected against direct
impingement by the flame and heat of a fire externally of
the valve and actuator assembly. The actuator mechanism also
protects the bonnet structure of the valve from corrosion in
the event the valve is employed in a corrosive environment.
The actuator connection flange is formed to define
a sealant passage and a sealant fitting is assembled to the
bonnet structure to allow injection of sealant material into
the packing chamber of the bonnet to enhance the sealing
capability of the stem packing. By forming a sealant injection
aperture in theshroud of the actuator housing, sealant material
may be injected into the packing chamber at any time without
necessitating removal of the valve actuator from the bonnet
structure.
In one aspect of the present invention, there is
provided a bonnet and actuator assembly for use with a valve
body and adapted to be connected thereto by bolts, comprising
a bonnet having a first outturned flange with bolt holes therein
adapted to receive said bolts to bolt the bonnet to the valve
body; an actuator housing, an actuator stem within said housing
_7_
1 16~8~ll
and adapted to be connected with a valve member in said valve
body stem actuator means in said housing and connected to
said stem for moving the stem, a substantially imperforate
shroud connected to said actuator housing and extending down-
wardly therefrom into engagement with said outturned flangeoutwardly of said bolt holes so as to protect bolts con-
necting the bonnet with the valve body, when assembled thereon,
from direct contact by heat from external fires and retarding
heat induced deterioration of bolts holding the bonnet to the
valve body.
BRIEF DESCRIPTION OF THE DRAWINGS
In order that the manner in which the above recited
advantages and features of the invention are attained and
can be understood in detail, more particular description
A
1 16~8~4
of the invention, briefly summarized above, may be had by
reference to the specific embodiments thereof that are i~l-
lustrated in the appended drawings, which drawings form a
part of this specification. It is to be understood, how-
ever, that the appended drawings illustrate only typicalembodiments of this invention and therefore are not to be
considered limiting of its scope, for the invention may
admit to other equally effective embodiments.
IN THE DRAWINGS
lC FIG. 1 is an elevational view of a pneumati~ valve
actuator constructed in accordance with the present inven-
tion with a major portion thereof broken away and illus-
trated in section and with a view to which the actuator is
connected partially illustrated in broken line.
FIG. 2 is an enlarged fragmentary sectional view of
the valvè actuator mechanism of FIG. 1, illustrating the
relationship of the spring plate and the diaphragm plate
to the valve stem.
FIG. ~ is a sectional view similar to FI~. 2 and il-
lustrating the actuator housing and diaphragm assembly be-
ing moved upwardly during separation thereof for repair or
replacement.
FIG. 4 is a partial sectional view of a valve actuator
mechanism representing a modified embodiment of this in-
vention. :
FIG. 5 is a fragmentary sectional view of a valve ac-
tuator mechanism representing a further modified embodi-
ment of this invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBOOIMENT
.
The present invention is discussed herein and illus-
trated in the drawings particularly in regard to pneumatic
1 16484~
type valve actuators. It is to be understood, however
thal: the invention applies effectively to any type of
valve actuator mechanism, such as hydraulic operators,
electrical operators, or manual operators, without limit-
ing the scope of the invention in any manner whatever.
Referring now to the drawings and first to FIG. 1,there is illustrated a valve actuator mechanism generally
at 10 which is of pneumatically energized character and
which is adapted to be interconnected with the bonnet por-
tion of a valve such as a gate valve, for example, whichis partially illustrated in broken line at 12. The valve
mechanism incorporates a valve body and a bonnet structure
illustrated generally at 14 is secured to the body by
means of a plurality of stud and nut assemblies such as
are illustrated in broken line at 16. ~he valve actuator
mechanism is related integrally with the bonnet structure
of the valve and is entirely supported by the valve bonnet
structure as will be evident from the following. The bon-
net structure incorporates a bonnet flange 18 defin~ng a
plurality of bolt holes 20 through which the studs extend
for threaded assembly within appropriate apertures formed
in the valve body.
The bonnet structure also incorporates an intermediate
section 22 through which a stem passage 24 is formed and
with an enlarged portion 26 of the stem passage defining a
packing chamber within which is received a packing 28. A
valve stem 30 extends through the stem passage 24, packing
28, and a stem passage 32 defined in a packing retainer
element 34 that is threadedly retained within the upper
portion ûf the bonnet structure. It is intended that the
present invention be equally adaptable to manual override
1 164844
type actuator systems as well as actuator systems incorpo-
rating integral valve stems as shown in the drawings. In
many systems of manual override, the stem will be threaded
internally to receive a threaded member which is connected
to the gate. The threaded member will be contained within
the stem such that line pressure does not act on any
cross-section of the threaded member, creating what is
generally known as a "balanced stem" manual override.
The packing retainer element 34 is also formed to de-
fine a lubricant chamber 36 that is disposed in registry
with a lubricant passage 38 through which lubricant mater-
ial is injected into the lubricant chamber. The sealant
passage is formed within an actuator connection flange 40
that is formed integrally with the bonnet structure and is
positloned in spaced relation with the bonnet flange 18.
A lubricant supply fitting 42 is threadedly received by
the actuator connection flange at the outermost portion of
the lubricant passage 38, thus providing means by which
lubricant material may be readily in~ected through passage
38 into the lubricant chamber 36. In the event the pack-
ing 28 should begin to leak, the leaked fluid will be ven-
ted by the fitting 42, thus preventing any buildup of
pressure between the stem packing and the 0-ring seals of
the packing retainer 34. The fitting thus provides a
"tattle-tale" feature to ensure that any packing leakage
is noticed and corrected. ~
To provide an adjustable stop for limiting downward
travel of the valve stem and gate, a stop body 33 is pro-
vided about the valve stem which is supported by the pack-
ing retainer 34. An externally threaded stop sleeve 35 isvertically ad~ustable relative to the internal threads of
the stop body 33 and is locked in place by a lock nut 37.
- 1 0--
1 1~4844
The spring plate 84 engages the stop sleeve at the desired
limit of downward travel thereof and thus achieves proper
positioning of the gate relative to the flow passage and
seats of the valve.
An mentioned above, when the stud and nut assemblies
of typical bolted bonnet valves are subjected to direct
heat from an external fire, the stud and nut assemblies
can become rapidly heated to the point that the yield
strength of the material from which the studs and nuts are
composed becomes drastically reduced. Under circumstances
where the valve is subjecte~ to high pressure, heat in-
duced deterioration of the structural integrity of the
stud and nut assemblies can cause sufficient yielding to
allow the bonnet connection with the valve body to lose
its sealing contact with the valve body, thereby allowing
valve leakage. If the product controlled by the valve is
of flammable nature, of course, valve leakage is highly
undesirable since the product leaking from the valve
would, in effect, be feeding the fire. It is desirable,
therefore, to provide valve actuator mechanism that re-
tards heating of the stud and nut assemblies and thereby
materlally prevents stud and nut failure and bonnet leak-
age as compared to conventional valve constructions.
In accordance with the present invention, a valve
actuator housing is illustrated generally at 44 and incor-
porates upper and lower housing sections 46 and 48, re-
spectively. An actuator connection shroud 50 is intercon-
nected with the lower housing section 48 by means of an
annular weld as shown at 52. The actuator connection
shroud 50 is of generally cylindrical form, defining an
internal cylindrical surface 54 that is received in close
fitting relation by external cylindrical surfaces 56 and
l 164844
58 that are defined respectively by the bonnet flange 18
and the actuator connection flange 40. A plurality of
connection apertures 60 is formed in the shroud 50, and
connection bolts 62 are extended through the apertures 60
and are received by threaded bolt apertures 64. The bolts
62 secure the shroud 50 and thus the actuator housing 44
in assembly with the actuator connection flange 40. The
bonnet flange 18 is formed to define an annular shoulder
.63 aga~nst which the lower extremity of the shroud 50
rests, thus properly positioning apertures 60 with respect
to bolt ap~rtures 62 of connection flange 40. Since the
lower portion of the cylindrical surface 54 bears against
the cylindrical surface 56 defined by the bonnet flange
18, the bonnet flange provides abutting and stabilizing
support for the actuator shroud and thus lends significant
structural integrity to the valve actuator housing. It
should be noted that the actuator housing structure may
also be of unitary nature, such as is the case where this
inventlon is incorporated in conjunction with hydraulic
actuator systems. It is not intended to limit this inven-
tion to pneumatic valve actuator systems such as shown and
described, it being apparent from this disclosure that the
inventton finds application in a wide range of valve actu-
ator systems.
~he actuator shroud 50 cooperates with the spaced
flanges 18 and 4~ to define an annular protective chamber
66 within which the upper portions of each of the studs
and the various nuts of the stud and nut assemblies are
located. If desired, the protective chamber 66 may be
~0 filled with air which, of course, is a poor conductor of
heat. In the alternative, in the event additi~nal heat
insulation quality is desired within the protective
-12-
1 16~844
chamber 66, a quantity ot` heat insulation material 68 may
fill the protective chamber 66, thus providing further
heat retarding characteristics and allowing the stud and
nut assemblies 16 to be not only free of direct flame im-
pingement, but also protected from rapid transfer of heatthrough the housing structure. The shroud also protects
the bonnet structure, including the stud and nut assem-
blies thereof from corrosion in the event the valve ana
actuator assembly are located in a corrosive environment.
The lower central portion of the bonnet structure is
formed to define a bore 70 within which an enlarged head
portion 72 of the valve stem 30 is received. The head
portion 72 of the valve stem is formed to define a frusto-
conical surface 74 that is adapted to engage a frusto-
conical surface 76 of differing angular relationship at
the uppermost position of the valve stem 30. These inter-
acting frusto-conical surfaces effectively promote the
development of a metal-to-metal seal that assists in pre-
ventlng stem leakage under circumstances where the valve
stem is moved to its position of maximum outward limit.
The upper portion of the actuator connection flange 40
is formed to define an annular spring positioning shoulder
78 about which is posltioned the lower extremity of a com-
pression spring 80 that bears against the upper surface of
actuator connection flange 40. The upper portion of the
compressiGn spring 80 is received about a spring position-
ing shoulder 82 that is defined by a spring retainer plate
84 and with the spring actually bearing against an annular
abutment surface 86 defined at the outer periphery of the
spring retainer plate.
With reference specifically to FIG. 2, the spring
plate also is formed to define a central opening 88
~ -13-
8 4 4
through which the valve stem 30 extends and defines a
bearing receptacle 90 within which is received a thrust
bearing assembly 92 with an upper thrust element 94 there-
of ~defining a recess 96 within which is adapted to be re-
ceived the lower portion of a thrust ring 98 such as a re-
tainer ring that is received within an annular groove 100
formed in the valve stem 30. As the compression spring 80
bears upwardly against the spring plate 84, the force of
the compression spring is transferred through the bearing
assembly 92 to the thrust ring 98 and thence to the valve
stem 30. The upwardly directed force of the compression
spring therefore is transmitted to the valve stem tending
to move it outwardly away from the valve body. In absence
of any opposing force, the return spring 80 will maintain
the valve stem ~0 at the outermost safe position thereof,
maintaining ~ctal-to-metal seal between the valve stem
and bonnet by virtue of the interacting frusto-conical
surfaces 74 and 76. Thus, line pressure will act on the
area of the metal-to-metal seal to exert a sealing force
~0 proportional to the magnitude of the flow line pressure.
As the return spring is compressed and extends during
actuation and return of the valve stem during valve opera-
tion, the spring winds and unwinds and thus imparts rota-
tional forces against the abutment surfaces supporting the
upper and lower extremities thereof. 8y virtue of the
thrust shoulder 92, rotational forces applied against
thrust shoulder 86 simply cause rotation of the spring
plate 84. The thrust bearing assembly effectively pro-
tects the valve stem 30 from being subjected to rotational
forces due to winding and unwinding of the compression
spring during operational sequencing.
-14-
. .
8 4 4
The upper and lower housing sections 46 and 48 define
connection flanges 102 and 104 that are each formed to de-
fine a plurality of apertures through which a plurality of
bolts 106 extends for the purpose of securing the upper
and lower housing sections in assembly. The bolts lû6 al-
so extend through a plurality of apertures defined in an
outer peripheral portion of a diaphragm 108 that separates
the actuator housing into an upper pneumatic energizing
chamber 110 and a lower spring return chamber 112. The
spring return chamber is vented to the atmosphere via a
vent plug 113 to compensate for volumetric change in the
spring return chamber 112 as the diaphragm 108 is moved.
In the event of a sudden pressure increase in the chamber
112, the vent plug 113, being composed of an elastomeric
yieldable material, will blow out of the vent plug open-
ing, thus providing greater venting capability to prevent
rupture of the housing. The inner peripheral portion of
the diaphragm 108 is interconnected by means of a plurali-
ty of bolts 114 to a diaphragm plate 116. A diaphragm
retainer ring 118 through which the bolts 114 extend es-
tablishes sufficient compression of the inner peripheral
portion of the diaphragm against the diaphragm plate so as
to develop a positive gas tight seal therewith. The cen-
tral portion of the diaphragm plate 116 is formed to de-
fine an aperture 120 through which the valve stem 30
extends. An annular seallng element such as an 0-ring 122
or the like Is positioned within an annular seal groove
formed in the valve stem and maintains a positive seal be-
tween the valve stem and diaphragm plate. The diaphragm
plate is also formed at the inner portion thereof to de-
fine a bearing receptacle 124 within which is recelved a
bearing assembly 126 having a circular thrust element
~16~8~4
128. The thrust element 128 defines a thrust receptacle
130 that is adapted to receive the upper portion of the
thrust ring 98. Thus, downward force induced by the dià-
phragm 108 to ~he diaphragm plate 116 responsive to in-
crease ~n gas pressure within the pneumatic pressure cham-
ber 110 causes the diaphragm plate 116 to apply a downward
force to the thrust bearing assembly 126. This downwardly
directed force is transferred through the thrust bearing
- assembly and thrust element 128 to the thrust ring 98,
thus causing transfer of downwardly directed force to the
valve stem 30. The downwardly directed force, therefore,
acts against the inherent force of the compression spring
80, compressing the spring and shifting thè valve stem
downwardly to the desired position.
~he bearing assemblies in both the spring plate and
diaphragm plate are beneficial in cases where a manual
overr~de of the type previously mentioned is incorpo-
ratéd. The manual override is accomplished by rotation of
the valve stem causing the threaded member connected to
the gate to move upwardly or downwardly. These bearings
thus prevent the torque imparted by rotation of the valve
stem from transferriny to the diaphragm plate or sprin~
plate.
At the upper central portion of the upper housing sec-
~5 tion 46 is connected a stem fitting 132 that is formed to
define a stem passage 134 through which the upper portion
of the valve stem 30 extends. An annular sealing element
136 such as an 0-ring or thé like is maintained within an
internal groove formed in the fitting 132 and is operative
to maintain a positive seal with the valve stem 30. A
stop ring 138 is positioned about the valve stem 30 within
the pressure chamber 110 and is operative to limit upward
-16-
1164~4~
movement of the diaphragm plate 116 wnder the force in-
duced bv the compression spring 80. The stop ring 138 is
of sufficient thickness to cause accurate positioning of
the flow port of the gate that is controlled by the valve
stem 30.
When it is desirable to remove the valve actuator
mechanism from the valve for the purpose of repair such as
replacement of a diaphragm, for example, the disassembly
procedure is simple and efficient. The actuator connec-
tion bolts 62 are removed after which the actuator housingassembly, including the upper and lower housing sections
and the shroud portion 50, is simply moved outwardly as
indicated in FIG. 3 until the actuator housing has been
completely withdrawn from the valve stem 30. The compres-
sion spring and spring retainer plate 84 will remain inthe position illustrated in FIGS. 1 and 2, thus ensuring
that the valve stem 30 is continuously maintained to its
outermost safe position during removal and replacement of
the valve actuator mechanism. After the valve actuator
~0 has been repaired, it may be assembled to the valve and
bonnet structure about the compression spring and spring
retainer plate assemblies simply by reversing the proce-
dure and inserting the valve stem 30 through the aperture
134 of the actuator fitting 132. The actuator is simply
~oved toward the valve and bonnet structure sufficiently
to cause the thrust ring 98 to be appropriately seated
` within the recess 130 of the thrust element 128. When
this is accomplished-, the apertules 60 of the actuator
shroud 50 will be reg~stered with the bolt holes 64 and
the bolts 62 may simply be threaded-in place and tightened
a~ter which the assembly procedure is complete. The fluid
connections may then be established between the pneumatic
-17-
1 16~844
supply and bleed conduits that communicate with the pneu-
matic pressure chamber 110.
Under circumstances where it is desirable that the
valve be placed back in service as rapidly as possible, a
replacement actuator may be installed in place of an actu-
ator that is removed for repair simply by following the
actuator assembly procedure identified hereinabove. It is
possible to remove and replace a pneumatic actuator within
a few minutes time through the use of ordinary tools.
Under circumstances where a degree of frictional con-
tact between the compression spring, spring plate and
thrust ring may be tolerated without adverse effect, the
valve actuator mechanism may conveniently take the form
illustrated generally at 140 in FIG. 4 where a valve actu-
ator incorporates ùpper and lower housing section 142 and
144, respectively, which are secured in assembly by bolts
and nuts 146. The outer peripheral portion of a flexible
diaphragm 148 is secured between the housing sections by
the bolts and nuts 146 while the inner peripheral portion
of the diaphragm is secured by a retainer ring 150 that is
maintained in sealed assembly with a diaphragm plate 152
by a plurality of bolts 154. The inner periphery of the
diaphragm plate is fitted closely with the valve stem 156
and is sealed with respect to the valve stem by a sealing
2S element 158, such as an 0-ring or the like, maintained
within a seal groove. The diaphragm plate 152 is also
~, . ... . . .
formed at thè inner peripheral portion thereof to aefine
an annular thrust receptacle 160 that is adapted to re-
ceive a thrust ring 162 that is supported within an appro-
priate groove 164 formed in the valve stem.
A spring retainer plate 166 defines an annular shoul-
der 168 that receives the upper extremity of the actuator
.. .
,. ..
.~ _
1~64844
compression spring 1~0. The inner peripheral portion of
the spring retainer plate receives the valve stem and is
formed to define an annular receptacle 172 that receivès
the thrust ring 162. The diaphragm plate is readily moved
l;inearly along with the actuator housing assembly to ac-
complish removal of the actuator housing in the same man-
ner as described above in connection with FIGS. 2 and 3.
The upper housing section 142 incorporates a stem seal
fitting 174 having suitable sealing element 176 that es-
tablishes a sealed relation between the stem seal fittingand the valve stem and thereby prevents leakage of the
pneumatic medium from the pressure chamber 178 of the ac-
tuator. Venting of the variable volume spring chamber 180
upon movement of the diaphragm is accommodated by a vent
plug 182 that is formed of elastomeric material and will
blow out of the vent plug aperture 184 in the event the
chamber 180 is subjected to excessive pressure.
An actuator connection shroud 186 of the same form as
described above and shown in FIG. 1 is interconnected in
any suitable manner with the lower housing section 144.
It may be desirable to accomplish various rotational
positioning of the actuator inlets or position indicating
switches regardless of the position of the valve to which
the actuator is assembled. This feature is effectively
accomplished in the manner illustrated in FIG. 5 wherein a
further modified embodiment of this invention is illustra-
ted in fragmentary section. An actuator connection flange
194 similar to that shown particularly at 4Q in FIG. 1 is
rotatably mounted on bonnet 190 to rest on a support
shoulder 192. The bonnet 190 is formed to define a seal-
ant injection and venting passage 196 (similar to passage
36 in FIG. 1) and is further formed to define a peripheral
,
1`16~4~
groove 198. The rotatable flange 194 defines a corres-
ponding sealant supply and injection passage 200 that is
provided with a fitting 202 at the outer extremity, which
fitting may be identical to fitting 42 of FIG. 1. The
bonnet 190 is sealed with respect to the outer periphery
of the rotatable flange 194 by means of upper and lower
sealing elements 204 and 206, which may be elastomer 0-
rings o~ any other suitable sealing devices. The rotata-
ble flange 194 is secured in assembly with the bonnet 190
by means of a retainer ring 208 that is received within an
appropriate groove formed in bonnet 190.
It is therefore apparent that the present invention is
one well adapted to attain all of the objects and advan-
tages hereinabove set forth together with other advantages
which will become obvious and inherent from a description
of the method and apparatus itself. It will be understood
that certain combinations and subcombinations are of util-
ity and may be employed without reference to other fea-
tures and subcombinations. This is contemplated by and is
within the scope of the present invention.
As many possible embodiments may be made of this in-
vention without departing from the spirit or scope there-
of, it is to be understùod that all matters hereinabove
set forth or shown in the accompanying drawing~ are to be
interpreted as illustrative and not in any limiting sense.
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