Note: Descriptions are shown in the official language in which they were submitted.
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- -~IALVE WIT~I HEAT-RESPONSIVE BEARING
AS5EME~LY PROVIDING BACK SEAT ARRANGEMENT
Back~round of the Invention
Gate valves, such as the one shown in
Crain et al, U~SO patent 3,349~789, issued October
31, 1967 often and necessarily are provided with
seals and packing that works well, lasts long and
maintains its inte~rity under ordinary
circumstances r but which is subject to being
damaged should there be a fire the heat of which
engulfs the valve for more than a short perîod of
time. ~ccordingly, proposals have been made for
providing such valves with a second line of
defense, which comes into play only if a fire or
the like should threaten to or actually destroy~
the integrity of the usual seals and packlng. A
typical environment where such a precaution is
worthwhile taking is where the valve is to be used
to control the egress of subterranean fluids (i~e.
20 as part of a petroleum well completion). Other
typical environments for use are petroleum
refineries, petrochemical complexes~ and chemical
manufacturing, processing, storage, handling
transporta~ion and use facilities.
According to some prior art proposals,
: the valve is provided with one or more fusible
- bodies which when in place, keep the back se~t
elements apart. Upon sub jection of the valve to
sufficient heat, the fusible body or bodies flow
out, permitting some crucial shifting of the valve
components that cause a metal ba~k seat seal to be
made up, providiny a measure of additional safetY.
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What the present invention provides is a convenient
way to provide the fusible body or bodies on valves of the
type described and for similar apparatus.
Summary of the Invention
The bearing assembly of a normally non-rising stem
gate valve is provided with an annulus of fusible material.
Upon subjection to a preselected temperature level, the
fusible body melts out of the way, permitting the stem to
rise slightly, effecting a metal-to-metal seal between the
valve stem and bonnet. This forms another line of defence
against consequences from loss of -the sealing normally
provided by the valve stem packing.
More specifically, the invention provides an
improvement for a normally non-rising stem valve having a
valve stem which passes out of a chamber in a valve housing
through a bonnet having a passageway in which a packing
assembly normally seals between the valve stem and the bonnet
and in which a bearing assembly journals the valve stem for
rotation relative to the bonnet and in which a retainer means
secures the bearing assembly relative to the bonnet against
substantial axial movement of the valve stem and of the
bearing assembly. According to the invention, the retaining
means includes a bonnet gland secured to the bonnet and
surrounding the bearing assembly. A retainer is secured to
the bonnet gland relatively exteriorly of the bearing
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assembly; and a body in the form of a washer-like annulus and
made of relatively low temperature fusible material is
physically axially interposed between the retainer and the
bearing assembly. Channel means are provi~ed out throu~h
which the fusible material may run when subjected to a
predetermined amount of relatively low temperature heat, so
that when the fusible material has run out, the valve stem is
free to rise to a limited extent. The channel means may
comprise at least one passageway through the bonnet gland
from the interior thereof to the exterior thereof. ~n
annular first metal sealing surface is circumferentially
provided on the valve stem, and a second metal sealing
surface is provided on the bonnet within the chamber, which
two sealing surEaces normally remain spaced axially apart but
which become annularly engaged in a sealed condition upon
rising of the valve stem by the aforesaid limited extent.
The bonnet gland comprises a tubular member having an
internally threaded outer end portion, and the retainer
comprises an externally threaded tubular retaining gland
threaded into the outer end portion of the bonnet gland. The
valve stem includes a radially outwardly projecting flange
and the bearing assembly includes a first bearing ring below
and in contact with that flange and a second bearing ring
above and in contact with that flange. The valve stem may
have a valve gate threadably connected therewith within the
chamber. A tubular spacer means is interposed b~tween the
second bearing ring and the annulus of fusible material.
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The principles of the invention will be further
discussed with reference to the drawings wherein a prefered
embodiment is shown. T~e specifics illustrated in the
drawings are intended to exemplify, rather than limit aspects
of the invention as defined in the claims.
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Brief Description of the Drawings
In the Drawings
; Figure 1 is a fragmentary longitudinal sectional
view of a gate valve provided with a heat responsive back
seat arrangement in accordance with principles of the present
invention. (The portions of the valve housing
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broken off at the opposite ends of the throughbore
are conventional, e.g. flanged ends, e.g. as shown
in the aforementioned prior U.S. patent of Crain
; et al.)
Figure ~ is an enlarged fragmentary
detail of Figure 1.
Detailed Description
Figures 1 and 2 each show the center line
of the valve 10 that coincides with the valve stem
axis. To the left of the center line the valve is
shown in a normal "open" condition and to the
right of the center line the valve is shown in a
normal "closed" condition.
Normally, this is a nDn-rising stem valve
and the main seal about the valve stem 12 between
the chamber 14 and the external environment where -
the valve stem 12 penetrates the valve housing 16
i5 conven~io~ally provided by packing 18 about the
stem 12 within the bonnet ~0 of the housing 16.
~owever, should there be a fire in the
vicinity of the valve 10 or great heat likely to
destroy or severely damage the packing 18, the
valve 10 has a safety feature which comes into
pIay, as follows. ~ ring 22 of fusible material
that is incorporated in the valve stem b~aring
assembly 24 melts and flows out of p~sition
through the holes 26. Pressure rom within the
valve then will raise the gate assembly sli~ht,
until a metal-to-metal back sea~ seal is formed by
circumferential abutment of the coaxially annular
surface A on the valve stem with coaxially annular
;; surface B on the bonnet 2~.
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A simple construction is shown~ e.g. a
manually operated valve with no provision for
automatically opening the valve if it is closed
nor for automatically closing the valve if it is
open. However, it should be understood that many
of the principles will apply to like valves
provided with automatic operators.
Some more details of what is shown in the
drawin~s will now be given in case the reader is
unfamiliar with the sort of valve that is shown.
The valve housing 16 includes a main body
28 with a horizontal throughbore 30 (in the
orientation shown in the drawings) with a chamber
14 that intersects the throughbore vertically
; 15 crosswise. The chamber 14 intersects the exterior
of the main body 28 at a site intermediate the
ends of the main body. There, the wall of tbe
chamber 14 is provided with a sealing surface 32
and the main body is provided with a tubular
por.ion 34 with an outer end surfa~e 36.
Below the sealing surface 32~ the wall of
;the chamber 14 is coaxially provided with an
axially outwardly facing ledge 38 (i.e. which
face~ in the same direction as the end surface 36
2; faces). A unitary, wedge-type gate expander 40
hangs into the chamber 14 in the body 28 from this
ledge 38. The expander 40 includes an annular
base 42 at its upper end. This base 42 rests on
the ledge 38. At two diametrically opposed ~ites,
the base 42 is provided with legs 44 whi~h
integrally depend therefrom and have gate
expanding wedge surfaces 46 formed thereon near
the lower ends thereofO
Where the valve throughbore 30 is
intersected by the chamber 14, the thro~hbore 30
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is circumferentially enlarged and each resulting
recess 47 receives a sealing ring 48.
~` The valve 10 further includes a bonnect
20 which matches the valve body tubular part 34 by
having a sinilar tubular part 50 with an end
surface 52, and internally having an annular ~:
sealing surface 54. In addition~ a
circumferential notch 56 is form~d where the
bonnet end surface 52 intersects the chamber 14 in
the bonnet.
The valve bonnet is sealed and secured to
the valve body by installing an opposed lîp,
externally circumferentially flanged sealing ring :
58 between the two parts to form a circumferential .
seal at 32 and 54, with the sealing ring rib being
; received in the notch 56; a ring of bolts 60 is
installed through the bonnet tubular part 50 into
the valve body tubular part 34.
: The valve bonnet 20 is shown including a
- 20 normally closed bleeder plug 62 installed in a ~:.
passageway 64 that leads to the upper reaches of
the chamber 14. The valve bonnet 20 also is shown
including a normally closed fitting 66 at the
external end of a passageway 68 leading to the
.~ 25 stem packing 18,-so that conventional pl~stic
compounds for energizing and/or normally renewing
the stem packing may be injected under pressure.
Centrally of its outer end wall 70, the
bonnet has a throughbore 7~. The sealing surface
B is provided circumferentially o the
intersection of the bonnet throughbore 7~ with the
valve chamber 14, in the upper reaches oE the
valve chamber 14. A ways above the sealing
surface B, the bore 72 i5 twice enlarged, once to
provide the recess in which the packing 18 is
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received, and above that to provide for the
elements which keep the packing in place, keep the
valve gate assembly in place, and journal the
valve stem for rotationO The region of the second
S enlargement and above can be thought of as an
outer tubular extension 74 of the valve bonnet
20. ~he sidewall of the extension 74 is shown
provided with a radial, internally threaded
opening 7& and a grease fitting 78.
Typically, the packing 18 will be a stack
of several washer-like elements, some of which are
retainers for the opposite ends of the stack, and
others being annuluses of somewhat resilient
and/or plastic material and still others being
15 configurea to admit pressur izing sealant fed in ~:
through the fittinq 66. ~ packing gland 80 is
shown following the assembly of packing 18 and
bottoming on the internal shoulder 82 at the base
of the tubular extension 74.
Where the s~em 12 passes through the
packing 18 and gland 80, it is of constant
radius~ A ways above the base of the tubular
extension 74, the stem 12 has a band 84 that is of
smaller diameter. Above that the stem is of its
aforesaid constant radius again, until after
reaching the exterior of the valve, the stem 12 is
provided with keying and threaded portions 86, 88
at its end 90. An operating hand wheel 92 is
shown mounted on the end ~0~ being keyed thereto
~` 30 at 86 an~ secured thereon through the use of a nut
94. Item 96 is the usual washer.
Above the set screw opening 76 and tne
grease f itting 78 the bore 72 OL the bonnet
extension 74 is in'Lernally threaded at 98 and
provided with sur~aces for accommodating a bonnet
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gland retainer wire 100 and a b~nnet rod wiper
102.
A tubular bonnet gland 104 that is
externally threaded at 106 is threaded into the
bore 72 until it engages the packing gland 80 and
a set screw 108 is threaded in through the opening
76 until it engages the packing gland 80 in an
external notch 110 in order to prevent the bo~net
- gland 104 from backing out. The bonnet gland 104
also is provided with surfaces for accammodating
the bonnet gland retainer wire 100 and the bonnet
rod wiper 102.
It should now be n~ticed that near its
outer end the bonnet gland 104 is internally
15 threaded at 112. The bonnet gland surr~unds and -:
houses radially between itself and the stem 12 a
number of important parts of ~he stem bearing
assembly 24. Shown, starting from the bottom, are
a spring washer 114 which seats on the packing
gland 80, a lower, roller bearing 116 for the stem
12, a split collar 118 assembled about the stem
into the recess at 84 for interfacing the stem
with its bearings, an upper, roller bearing 120
. and a tubular s.pacer 12~ with a bearing bushing
124 between it and the stem 12. The radially
~ outer corner of the upper end of the ~pacer 122 is
;~ shown circumferentially relieved to provide a
recess 126, radially inwardly backed by a
`: remaining tubular web of the upper end re~ion of
3Q the bearing bushing 124. The lower part of this
recess 126 receives a washer-like annulus of
fusible material 22. An externally threaded
tubular re~ainer gland 128 is screwed into the
upper end of the bonnet gland until its ~ose
3s axially engages the fusible body 22. ~t should be
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apparent that this step n~rmally secuxes the valve
stem against rising, while leaving the valYe stem
free to be rotated by rotation of the handwheel
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The retainer gland encirGles the stem 12
near the hand wheel and is internally configured
at its upper end to accommodate an annular valve
stem wiper 130.
Down in the chamber 14, the stem 12 is
shown having a lower, externally threaded portion
132. The valve gate 134 includes upstream and
downstream plates 136 with wedge follower surfaces
138 at their edges. ~ach plate 136 has a bore 140
for alignment with the valve body throughbore 30
when the valve is in an open condition and an
upper, blind portion 142 which is lowered into
blocking relation with the valve body throughbore
30 when the valve is closed.
In order to threadably connect the gate
plates to the stem 12 so that when the hand wheel
92 is turned the gate is raised and lowered~ the
gate plates are assembled at ~heir upper ends
about an internally threaded drive bushing 144
that is keyed to the gate plates by a torque plate
25 146. (See McGee, U.S. patent 4~138,091, is~ued
February 6, 1979 for more details).
Should the valve 10 be subjected to such
heat that the in tegr ity of the packing 18 and
sealing 48 be degraded, the tempera~ure also will
be sufficient to destroy the ring 2~, by making it
so plastic, so runny or so crumbly ~hat it flows
out the holes 26 provided in the bonnet gland
radially beside its position. Pressure from
within the valve, if any fluid is attempting to
escape past the damaged seals and packing~ then
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will raise the gate assembly slightly, until a
metal-to-metal back seat seal is formed at A, B.
Any material customarily used for
; fusible, heat-destructed bodies for instance as
5 conv~ntionally used in automatic sprinkling
systems may be used. T~pical material are metals
containing lead, bismuth, indium and/or cadmium as :
principle low temperature-mel~ing alloying
constituents~ Similarly acting plaistic resin
materials are commerciaily available for use in
this context.
It should now be apparent that the valve
with heat-responsive back seat arrangement as
described hereinabove, possesses each of the
attributes set forth in the specification under
the heading "Summary of the Invention"
hereinbefore. Because it can be modified to ~ome
extent without departing from the principles
thereof as they have been outlined and explained
in this specification, the present invention
should be understood as encompassing all such
modifications as are within the spirit iand scope
of the following claims.
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