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Патент USA US3079045

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Feb. 26, 1963
w. R. MERCER
3,079,035
PRESSURE ACTUATED CLOSURE ASSEMBLY
Filed July 3, 1961
W////am ?’. Mercer
INVENTOR.
Z02” Z AM
United States Patent O?lice
3,079,035’
Patented Feb. 26, 1953
1
2
3,079,935
matic relief of pressure when the internal pressure exceeds
the design limit of the pressure vessel.
The pressure vessel of the present invention has an
PRESSURE ACTUATED CLOSURE ASSEMBLY
William R. Mercer, Houston, Tern, assfgnor to ACF _In
dustries Incorporated, New York, N.Y., a corporation
of New Jersey
Filed July 3, 1961, Ser. No. 121,516
7 Claims. (Cl. 220-46)
opening with an outwardly converging tapering wall.
Positioned in the opening is a closure member having a
similarly tapering wall. A seal ring having mating sur
faces is interposed between the closure member and wall
of the pressure vessel. Axially outward of the closure
This invention relates generally to a pressure actuated
member and seal ring there is provided a stop ring which
metallic seal ring closure assembly for pressure vessels in 10 will contact the closure member and seal ring to restrain
high pressure service.
axially outward movement of the closure member and
One type of pressure vessels to which the invention is
seal ring after su?‘lcient movement to establish a seal.
particularly applicable is valves. Most valves have an
The stop is so positioned that the closure member and
open-ended valve chamber in which is positioned the in
seal ring can move out a controlled amount to effect a
ternal valve mechanism. The opening to the valve cham 15 seal, however, axially outward movement past this point
ber is closed by a disengageable bonnet which permits
is restrained by the stop. Thereafter, axial outward move
entry into the chamber to make necessary repairs to the
ment of the closure member and seal ring is restrained
internal valve mechanism. Many other pressure vessels
and any further build-up in internal pressure will be in
require a similar type opening where periodic entrance
hoop stress which will tend to increase the size of the wall
into the interior of the pressure vessel is desirable. The 20 or decrease the bearing pressure between the wall of the
most common method of sealing the valve chamber open
opening and ring thereby effecting a leak between these
ing has been to have a ?anged bonnet bolted to the valve
two surfaces to relieve excessive pressure. Upon relief of
body with suitable means between effecting a seal. Such
the excessive pressures, the normal resiliency of the mate
method is relatively expensive and time consuming to as
rial forming the wall of the opening will bring it back into
semble and disassemble.
25 sealing contact with the seal ring. The load on the stop is
Another method of sealing such openings, which has
not multiplied by any wedging action and therefore can
met with considerable success in the valve art, has been
to provide a pressure actuated seal. In one type of such
seal the opening is provided with a frusto conical surface
be controlled with a smaller mass. The smaller mass also
permits su?‘icient expansion to cause a leak before rupture.
It is an object of the present invention to provide a
convergingly tapered axially outward. A circular bonnet 30 pressure actuated metallic seal ring closure assembly
or closure member havinrr a similarly tapered peripheral
surface and small enough to pass through the opening op
poses the wall of the opening. A metallic ring is posi
which is so constructed that there is a controlled auto—
matic relief of excessive body pressures.
It is another object to provide a pressure actuated
tioned between the closure member and wall of the open
closure assembly in which the axially outward movement
ing to form a seal between the closure member and wall 35 of the closure member and seal ring is controlled, and
of the opening. The internal pressure in the body exerts
after movement for sealing load is transferred to expan
a force upon the closure member which tends to move
sion of the wall to decrease bearing pressure between the
the closure member axially outward. The seal ring is
wall and ring to permit automatic relief of excess pres
su?’iciently pliable to be forced into intimate contact with
the closure member and wall of the opening effectively
sealing the opening. As the pressure increases, the
sure thereby preventing rupture.
It is a further object to provide a pressure actuated
closure assembly in which after a controlled amount of
closure member and seal ring attempt to further move
axially outward. The axially outward movement of the
closure member and seal ring is resisted by the wall of the
axially outward movement of the closure member, the
opening. As the internal pressure increases, the hoop
stress of the wall surrounding the opening correspond
crease in pressure will cause the wall of the opening to
ingly increases due to the outward movement of the
closure member and seal ring tending to expand the open
ing; therefore, the wall of the opening must be of a suffi
wall and seal ring, permitting excessive pressure to escape
and return to sealing condition.
cient mass so as to resist expansion.
While the pressure
actuated sealing arrangement has the advantage of using
the load multiplying e?’ect of the angular surfaces to
closure member contacts a stop which restrains any
further axially outward movement whereby further in
expand within its elastic limit, decreasing bearing between
It is a further object to provide a pressure actuated
closure assembly in which the mass of the outer wall of
the pressure vessel can be maintained at a minimum.
Other and further objects of the invention will be ob
establish a seal with a small axial force, it has the dis
vious upon an understanding of the illustrative embodi~
advantage of requiring an extremely large mass to resist
ment about to be described,’ or will be indicated in the
55
the outward movement of the closure member and seal
appended claims, and various advantages not referred
ring and has a tendency to build up unduly high hoop
to herein will occur to one skilled in the art upon employ
stresses as high axial loads are applied. Examples of
ment of the invention in practice.
such closures are fully disclosed in M. P. Laurent’s United
A preferred embodiment of the invention has been
States Patents, 2,582,995, 2,582,996, and 2,582,997.
chosen for purposes of illustration and description and is
In order to take advantage of the multiplying effect of 60 shown in the accompanying drawings, forming a part of
angular surfaces to form a tight seal with small axial
the specification, wherein:
loads and at the same time eliminate unduly high hoop
FIG. 1 is a vertical cross-sectional view of a valve
stresses, the closure assembly of the present invention
equipped with the closure assembly of the present inven
utilized the above-described pressure actuated seal con
tion.
struction to attain the seal. However, continuous axial 65
FIG. 2 is an enlarged sectional view of a portion of
outward movement of the closure member and seal ring
the closure assembly showing in an exaggerated manner
is restrained. Such construction transfers the load from
expansion of the body and automatic relief on excessive
bearing pressure on the wall resulting from movement of
pressure.
the closure and seal ring to expansion of the wall by inter
While the closure assembly is shown incorporated in a
nal pressure. The expansion of the wall reduces the bear 70
valve, it can be readily seen that the closure assembly
ing load between the wall and ring providing an auto
of the present invention may be utilized as a closure as
3,079,035
3
4
tightly will the closure be seated and the better it will
sembly for an opening in any type of pressure vessel.
The term “pressure vessel” employed herein is intended
to include any structure of whatever description capable
of retaining substance under pressure which is provided
perform its function. It is so designed that upon de
crease in pressure the closure will back off to the amount
necessary to seal.
In order to prevent more axial outward movement than
with an opening to furnish access to the interior thereof.
is necessary to establish a tight seal, previous assemblies
The invention relates to a means for effecting the closure
reinforce the wall adjacent to the opening by-utilizinga
considerablemass of material. In order to cut down on
of the opening of such a vessel and not speci?cally to
the nature or purpose of the vessel.
the size of the Wall and to still limit the amountof axial
vReferring now to the drawings, the pressure vessel
chosen for purpose of description is a valve. The valve 10 outward movement, the present invention has a stop 40
incorporated in the opening 16 axially outward of the
is formed of a valve housing 10 which is in effect a pres
seal ring 30. This stop 40 may be formed, as shown
sure vessel. The valve housing has a flow passage 12
in the drawing, by threading the axial outer end of the
therethrough which is interrupted by an open-ended valve
opening 16 and threadedly engaging the stop 40 there
chamber 14 having an opening 16. Valve seats 18-—18
are arranged in the flow passage 12 at each side of the 15 with.‘ if the opening is too large for threading, other
means may be utilized to properly secure the stop 40.
chamber 14 to provide seating surfaces for a valve mem
The stop 44} is positioned axially outward of the seal
ber 20. A valve stem 22 is attached to the valve member
ring 36 so that the seal ring can move su?iciently so that
20 providing reciprocatory movement to move the valve
a tight metal-to-metal seal is formed between the closure
member 20 into and out of sealing contact with the seats
18—18. The stem 22 extends outwardly of the valve 20 member-seal ring—wall, see FIG. 1, at all pressures up
to the design limit of the structure. The stop 40 will
chamber 14 through a sealed passage 24 in a bonnet or
restrain axial outward movement of the seal ring 30 be
closure member 26 closing the opening 16. Leakage be
yond a set amount. It has been found that spacing the
tween the stem 22 and passage 24 is prevented by a stuff
stop approximately 1&2" from the point of initial assem
ing box 28. As will be explained subsequently, the space
between the bonnet 26 and the wall of the opening 16 25 bly permits suiiicient axial outward movement to satis
factorily provide a seal. It is desirable that the stop be
is closed by’ a seal ring 36.
adjustable to take care of slight variations in manufac
The bonnet assembly is insertable and removable rela
turing tolerances. Having a threaded stop as shown in
tive to the valve housing to permit the renewing of the
the drawings, the closure can be assembled, the bonnet
various working parts of the valve such as the stem,
valve member, and seats while the valve remains in the 30 pulled outward to obtain a seal, the stop threaded inward
until it contacts the bonnet, and then backed off the
line. Since lading ?owing through the valve gets into
necessary amount.
the‘ valve chamber 14, it is essential that a seal be main’
During normal operation of the valve, the principal
tained between the closure bonnet 26 and opening 16.
load
is carried by the contact between surface 32 with the
To provide the necessary seal, the peripheral surface
of the wall 32 de?ning the opening 16 is generally frusto 35 outer peripheral surface of the seal ring 30 and surface 34
with the inner peripheral surface of the seal ring 30 which
conical, taperingly converging axially outward of the
causes a sufficiently high bearing pressure to maintain a
housing. The closure member 26, which is circular in
positive seal. In effect, the closure of the present inven
plan, has a similar outwardly converging tapered surface
tion works similarly to that disclosed in the previously
34 commencing at the axial outer end of the closure
member. The taper of the surface 34 is a lesser taper 40 mentioned Laurent patents. Internal pressure in the cham
ber 14 will act upon the bottom of the closure member 26
than the Wall 32 of the opening. The surfaces 32 and
and seal ring 30 respectively. Thus, any variation in the
34 may converge in respect to each other as taught by
size of the parts due to expansion or contraction or any
the Laurent United States Patents 2,582,995, 2,582,996,
_
fluctuations in pressure will be compensated for by equiv
and 2,582,997; however, by using the closure assembly
alent movement of the closure member 26 and seal ring 39,
of ‘the present invention it is not necessary to employ
and it will be unnecessary to attend to the valve to periodi
the tapered-wedge ring to retain the closure member in
cally adjust it to maintain a seal ‘because the seal is auto
the opening, and if desired surfaces 32-34 may be of
matically maintained as a function of the internal pres
the same tap'cr. The maximum diameter of the closure
sure. However, if the internal pressure starts to exceed
member 26 is less than the minimum diameter of the
frusto conical opening 16 so that the closure member 26 50 the limit for which the closure is designed,‘ the closure
member 26 and seal ring 30 will contact the stop 40 and
may ‘be inserted'through the frusto conical opening 16.
further outward axial movement of the closure member
The peripheral wallsu-rface 32 of the frusto conical
26 and seal ring 30 will be arrested. When the axial out
opening 16 is spaced apart from the tapered surface 34
ward movement of the closure member 26 and seal ring
of the closure member 26 when the closure member 26
is in operative position and the metallic seal ring '30 is 55 30 terminates as a result of the stop 40, the principal load
is transferred from the contact ‘between the seal ring 30
positioned in such space. The seal ring 30 has inner and
and surfaces 32-64 to load on the stop 4t).v The wall of
outer surfaces corresponding to the surfaces 32—-34. If
the housing will continue to expand as the pressure ‘in
desired, the closure member 26 may be provided with a
creases reducing the bearing pressure between the seal
shoulder 36 adjacent its inner axial end ‘contacting the
inside portion of the inner axial end face of the seal 60 ring 30 and surfaces 32—-34.
As the bearing pressure between the seal ring 30 and the
ring to insure stability of the seal ring‘30 in reference to
surfaces 32—34 decreases and there is an increase in inter
'the' closure member 26. To obtain the initial seal of
nal pressure, the internal pressure will overcome the seal
said closure assembly, there is a clamp ring 38 which‘
and leak past the seal ring 31) allowing the excessive pres
engages the bonnet 26 and top of the body and allows
the bonnet 26 to be moved axially outward thus engaging 65 sure to escape, see FIG. 2. The ?uid ?owing past the
seal ring will flow out past the clamp ring. This how off
the seal'ring' 30 with the surface 34 of the bonnet and
surface 32 of the opening.
'
With such construction, as the internal body pressure
of ?uid will decrease the pressure and as long as the elastic
limit of the body material has not been exceeded, the
body material will come back to its original size reinstat
increases the closure member 26 tends to move axially
outward. ‘Such movement forces the inner and outer 70 ingthe seal between the seal ring 30 and surfaces 32-34.
Therefore, the present closure provides an automatic re
surfaces of-the seal ring 30 into intimate contact with
lief and prevents rupture of the valve. Once pressure is
the surfaces 32—34 of the housing and closure member
restored within designed limits, the seal will again auto
increasing the bearing pressure between these surfaces
matically function.
thereby forming a tight metal-to-metal seal. It will be
apparent that the greater the internal pressure the more 75 As can be seen from the foregoing, the present inven
5
3,079,035
tion discloses a pressure actuated closure assembly for
sealing the openings of pressure vessels which is so con
structed that during the design limit of the vessel the clo
sure assembly will tightly seal and upon an increase in
excess of design limit will automatically relieve the excess
6
‘internal pressure expands the housing decreasing the‘ bearing load between the tapered surface of the housing, the
peripheral surface of the closure member and the periph
eral surfaces of the sealing ring to permit automatic relief
of excessive pressures.
3. A gate valve comprising a housing having an open
pressure preventing rupture of the vessel.
As various changes may be made in the form, construc
tion and arrangements of the parts herein without depart~
ing from the spirit and scope of the invention and without
ended chamber, an axially outwardly converging tapered
surface forming the opening of said chamber, the axial
surface forming the opening of said chamber, the axial
ring having peripheral surfaces mating with the tapered
outer end of the surface being of a smaller diameter than
sacri?cing any of its advantages, it is to be understood that 10 is the axial inner end, a bonnet for said opening insert
all matter herein is to be interpreted as illustrative and
able through said opening, an axially outwardly tapered
not in a limiting sense.
peripheral face on said bonnet of a lesser taper relative
I claim:
to the axis of the opening than the taper of the wall form
1. A gate valve comprising a housing having an open
ing the opening, a seal between said bonnet surface and
ended chamber, an axially outwardly converging tapered 15 the surface of said opening comprising a metallic seal
outer end of the surface being of a smaller diameter than
is the axial inner end, a bonnet for said opening insertable
through said opening, an axially outwardly tapered periph
surface of the opening and tapered peripheral face of the
bonnet, a shoulder on the bonnet adjacent the axial outer
end of the tapered peripheral surface thereof, a clamp
eral face on said bonnet of a lesser taper relative to the 20 ring engaging said body and bonnet to move the bonnet
axis of the opening than the taper of the wall forming
and seal ring into said opening to form a seal for said
the opening, a seal between said bonnet surface and the
opening, a stop ring positioned in the opening axially
surface of said opening comprising a metallic seal ring
outward of said bonnet and seal ring threadedly engaged
having peripheral surfaces mating with the tapered surface
with the threaded portion and extending into said open
of the opening and tapered peripheral face of the bonnet, 25 ing to limit the axial outward movement of said bonnet
.a shoulder adjacent the axial inner end of the bonnet
contacting the inner axial end of the seal ring, a second
shoulder on the bonnet adjacent the axial outer end of
and seal ring, said stop ring being positioned su?iciently
distant from the said shoulder of the bonnet and the axial
outer end of the metallic seal ring when such bonnet and
the tapered peripheral surface thereof, a clamp ring en
seal ring are at their point of initial assembly so as to
gaging said body and bonnet to move the bonnet and seal 30 permit su?icient axial outward movement thereof to form
ring into said opening to form a seal for said opening, a
a seal but restraining further axially outward movement
threaded portion in the surface of said opening spaced
thereof whereby a fur-ther increase in internal pressure
axially outward of said bonnet and seal ring, a stop ring
expands the housing decreasing the bearing load between
the tapered surface of the housing, the peripheral surface
of the closure member and the peripheral surfaces of the
sealing ring to permit automatic relief of excessive
threadedly engaged with the threaded portion and extend
ing into said opening to limit the axial outward movement 35
of said bonnet and seal ring, said stop ring being posi
tioned suf?ciently distant from the said second shoulder
pressures.
of the bonnet and the axial outer end of the metallic
4. A gate valve comprising a housing having an open
seal ring when such bonnet and seal ring are at their
ended chamber, an axially outwardly converging tapered
point of initial assembly so as to permit su?icient. axial 40 surface forming the opening of said chamber, the axial
outward movement thereof to form a seal but restraining
outer end of the surface being of a smaller diameter
than is the axial inner end, a bonnet for said opening
further axially outward movement thereof whereby a fur
insertable through said opening, an axially outwardly
ther increase in internal pressure expands the housing de
tapered peripheral face on said bonnet, a seal between
creasing the bearing load between the tapered surface of
the housing, the peripheral surface of the closure mem 45 said bonnet surface and the surface of said opening com
prising a metallic seal ring having peripheral surfaces
ber and the peripheral surfaces of the sealing ring to
mating with the tapered surface of the opening and
permit automatic relief of excessive pressures.
tapered peripheral face of the bonnet, a shoulder ad
2. A gate valve comprising a housing having ‘an open
jacent the axial inner end of the bonnet contacting the
ended chamber, an axially outwardly converging tapered
surface forming the opening of said chamber, the axial 50 inner axial end of the seal ring, a second shoulder on
the bonnet adjacent the axial outer end of the tapered
outer end of the surface being of a smaller diameter than
peripheral surface thereof, a clamp ring engaging said
is the axial inner end, a bonnet for said opening insertable
body and bonnet to pull the bonnet and seal ring into
through said opening, an axially outwardly tapered periph
said opening to form a seal for said opening, a stop ring
eral face on said bonnet of a lesser taper relative to the
axis of the opening than the taper of the wall forming 55 positioned in said opening axially outward of said bonnet
and seal ring and extending into said opening to limit the
the opening, a seal between said bonnet surface and the
axial outward movement of said bonnet and seal ring,
surface of said opening comprising a metallic seal ring
said stop ring being positioned su?iciently distant from
having peripheral surfaces mating with the tapered surface
the said second shoulder of the bonnet and the axial outer
of the opening and tapered peripheral face of the bonnet,
a shoulder on the bonnet adjacent the axial outer end of 60 end of the metallic seal ring when such bonnet and seal
ring are at their point of initial assembly so as to permit
the tapered peripheral surface thereof, a clamp ring en
gaging said body and bonnet to move the bonnet and
seal ring into said opening to form a seal for said opening,
a threaded portion in the surface of said opening spaced
su?icient axial outward movement thereof to form a seal
ing into said opening to limit the axial outward movement
the closure member and the peripheral surfaces of the
but restraining further axial outward movement thereof
whereby a further increase in internal pressure expands
axially outward of said bonnet and seal ring, a stop ring 65 the housing decreasing the bearing load between the
tapered surface of the housing, the peripheral surface of
threadedly engaged with the threaded portion and extend
of said bonnet and seal ring, said stop ring being posi~
tioned su?iciently distant from the said shoulder of the
sealing ring to permit automatic relief of excessive
pressures.
5. A gate valve comprising a housing having an open
bonnet and the axial outer end of the metallic seal ring 70
ended chamber, an axially outwardly converging tapered
when such bonnet and seal ring are at their point of initial
assembly so as to permit sufficient axial outward move—
surface forming the opening of said chamber, the axial
outer end of the surface being of a smaller diameter than
ment thereof to form a seal but restraining further axially
is the axial inner end, a bonnet for said opening insert
outward movement thereof whereby a further increase in 75 able through said opening, an axially outwardly tapered
3,079,035
‘
,
8
peripheral'face on‘said bonnet, a sealrbetweensaid bon
net surface. and the, surface, of saidopening comprising
a metallic sealring havingperipheral-surfaces mating
with_ the, tapered surface of the opening and: tapered
' her and seal ring, said stop ring‘beingpositioned su?i
~ciently distant from the point of, initial assembly so as
to permit su?icient axial outward movement thereof to
peripheral face of the bonnet, a shoulder on the bonnet
sure expands the housing decreasing the bearing load
between the tapered surface-of the housing, the periph
eral surface of the closure member and the peripheral
surfaces of the sealing ring to permit automatic relief of
10 excessive pressure.
adjacentthe axial outer end of the tapered peripheral
surface thereof, a clamp ring engaging said body and
bonnet to'pull the bonnet and seal ring into said open
ing to form a seal for said opening, a stop ring positioned
in said opening axially outward of said bonnet and seal
ring and extending into said opening to limit the axial
outward movement of said bonnet and seal ring, said
stopring being positioned su?iciently distant from the
form a sealbut restraining further axially outward move
ment thereof whereby a further increase in internal pres
7. A closure, assembly for an opening in a pressure
vessel comprising; a pressure vessel having an opening
in a wall thereof, the peripheral surface of thewall de
?ning the opening taperingly converging, outwardly of
shoulder of ‘the bonnet and the axial outer end of the
metallic seal ring when such bonnet and seal ring are at 15 the vessel, arclosure member for said opening insertable
their point of initial assembly so as to permit su?icient
through said opening, an axially outwardly tapered pe
ripheral face on said closure member, the peripheral, wall
surface of said frusto conical opening being spaced apart
straining further axial outward movement thereof
from the tapered peripheral face ofsaid closure member
whereby a further increase in internal pressure expands
the housing decreasing the bearing load between the 20 when the closuremember is in operative position pro
viding a space therebetwecma metallic annular sealvring
tapered surface of the housing, the peripheral surface of
interposed between the tapered peripheral face of said
the closure member andthe peripheral surfaces of the
closure member and the wall of said opening, said ring
sealing ring to permit automatic relief of excessive
axial outward movement thereof to form a seal‘but re
pressures.
6. A closure assembly for anopening in a pressure’
forming a seal between said closure member, and said
opening, a shoulder on the closure member adjacent the
axis outer end of the tapered peripheral surface thereof,
means engaging the pressure vessel and closure member
to pull the closure member and seal ring into operative
?ning the opening taperingly converging outwardly of
position, a stop in said openingaxiallyoutward of said
the vessel, a closure member for said opening insertable
ring extending into the opening to restrain axially
through said opening, an axially outwardly tapered 30 seal
outward movement‘of said closure member and seal ring,
peripheralfaceon said closure member, the peripheral
said stop ring being positioned sufficiently distant from
wall surface of said frusto conical opening being spaced
the point of initial assembly so as to permit sufficient
aparttfrom the tapered peripheral face of said closure
axial outward movement thereof to form a seal but re
member when the closure member is in operative posi
straining further axially outward movement thereof
tion providing a space therebetween, a metallic annular 35
whereby a further increase in internal pressure expands
seal ring interposed between the tapered peripheral face
the housing decreasing the bearingload between the ta
of said closure member and the Wall of said opening, said
pered
surface of the housing, the peripheral surface of
ring forming a- seal between said closure member and
the closure member and the peripheral surfacesof the
said opening, a shoulder adjacent the axial inner end of
the closure member contacting the axial inner end of the 40 sealing ring to permit automatic relief of excessive pres
vesselgcornprising: a‘ pressure vessel having an opening
in, a wall thereof, the peripheral surface of the wall de
seal ring, a second shoulder on the closure member ad
jacent the axial outer end of the tapered peripheral sur
face thereof, means engaging the pressure vessel and clo
sure member to pull the closure member and seal ring
into operative position, a stop in said opening axially out
ward of said seal ring extending into the opening to re
strain axiallypoutward movement of said closure mem
sure.
References Cited in the'?le of this patent
UNITED STATES PATENTS
2,582,995 r
2,810,494
Laurent _______________ __ Jan. 22, 1952
Smith ______________ __ Oct. 22, 1957
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