U.S. patent number 3,659,624 [Application Number 05/025,976] was granted by the patent office on 1972-05-02 for fire safety valve.
This patent grant is currently assigned to Otis Engineering Corporation. Invention is credited to John V. Fredd, Warner M. Kelly.
United States Patent |
3,659,624 |
Kelly , et al. |
May 2, 1972 |
FIRE SAFETY VALVE
Abstract
A heat responsive safety valve having a fusible material holding
the valve at an open position. In one form the fusible material
mechanically locks the valve open. In another form, the fusible
material holds fluid pressure within a closed cylinder biasing a
valve to its open position. In each form of the valve, the fusible
material melts or otherwise weakens at a predetermined temperature
releasing the valve to close shutting off flow through the
conductor controlled by the valve as a fire-preventing measure.
Inventors: |
Kelly; Warner M. (Houston,
TX), Fredd; John V. (Dallas, TX) |
Assignee: |
Otis Engineering Corporation
(Dallas, TX)
|
Family
ID: |
21829118 |
Appl.
No.: |
05/025,976 |
Filed: |
April 6, 1970 |
Current U.S.
Class: |
137/75;
137/72 |
Current CPC
Class: |
F16K
17/383 (20130101); Y10T 137/1797 (20150401); Y10T
137/1819 (20150401) |
Current International
Class: |
F16K
17/38 (20060101); F16K 17/36 (20060101); F16k
017/38 () |
Field of
Search: |
;137/72-77 ;220/89B
;169/19 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Cohan; Alan
Assistant Examiner: Gerard; Richard
Claims
What is claimed and desired to be secured by Letters Patent is:
1. A fire safety valve comprising: a valve body; a valve movable
between open and closed positions in said body; means biasing said
valve toward said closed position; a housing on said valve body,
said housing having an internal annular surface portion defining a
locking shoulder and an enlarged internal annular surface portion
defining a collet release recess; a stem on said valve having an
end portion extending into said housing; and means for holding said
valve at said open position including a compressible locking collet
releasable disposed in said housing, a first end of said collet
engaging said end portion of said valve stem in said housing for
holding said stem against movement toward said closed position of
said valve, a second compressible end of said collet engaging said
locking shoulder in said housing, said second end of said collet
being releasable from said shoulder responsive to inward camming
action of said shoulder on said collet compressing said collet
inwardly and fusible means within said second end of said collet
and responsive to a predetermined temperature holding said second
end of said collet against compression and release from said
locking shoulder whereby said collet holds said valve stem against
movement toward said closed position of said valve until said
fusible means releases said collet responsive to said predetermined
temperature to permit said locking shoulder to compress said second
end of said collet for movement past said locking shoulder and said
first end of said collet to move into alignment with said release
recess of said housing to allow said stem to move to said valve
closed position.
2. A valve as defined in claim 1 wherein said collet has an
internal annular recess in the upper end thereof and said fusible
means in a disc disposed in said annular recess.
Description
This invention relates to safety devices and more particularly
relates to a fire safety valve for a flow line.
Flow conductors in well heads, pipe lines, and the like are
particularly susceptible to fire, especially when they are carrying
flammable fluids such as oil and gas. When fire occurs due to a
leak in such a conductor, or in the vicinity of such a conductor
and its valves, damage is minimized by an immediate closing of such
valves. Conventional valves have no means for closure responsive to
temperature, and, of course, if within a fire area, often cannot be
reached to be manually closed. Also, conventional valves often
contribute to a fire hazard in the sense that the packing in such
valves may be sufficiently damaged by a fire that the valve itself
becomes a contributor to the hazard with flammable fluid leaking
outwardly feeding the fire from the valve. While many systems have
been employed in the past to detect and function responsive to
fires, they generally are somewhat complex in nature, expensive,
and may be subject to malfunction.
It is an especially important object of the invention to provide a
new and improved safety device to provide protection against fire
hazards.
It is an especially important object of the invention to provide a
new and improved safety valve operable responsive to exposure to a
fire.
It is another object of the invention to provide a fire safety
valve which is mechanically held at an open position by a fusible
material and released for movement to a closed position responsive
to the melting or destruction of such material by a fire or
exposure otherwise to a temperature above a predetermined level
which might effect a fire in a system including the safety
valve.
It is another object of the invention to provide a gate type valve
locked open by a collet which is expanded to release such valve for
movement to its closed position and which is held against expansion
by a fusible ring.
It is another object of the invention to provide a gate type valve
held at an open position by a compressible collet held at its
normal position by a fusible member and released for compression to
allow the valve to close.
It is a still further object of the invention to provide a fire
safety valve of the gate valve type having a valve stem held by a
locking cap connected with the valve body by a fusible bushing.
It is another object of the invention to provide a fire-safety
valve held at its open position by pressure within a chamber
enclosing a piston connected with the valve stem, such pressure
being releasable through a fusible plug connected with the chamber
wall.
These and other objects of the invention will be apparent from
reading the following description of fire safety valves embodying
the invention taken in conjunction with the accompanying drawings
wherein:
FIG. 1 is a view in section of a gate valve mechancially locked at
an open position by safety apparatus embodying the invention;
FIG. 2 is an enlarged fragmentary view in section of the safety
locking device shown in FIG. 1;
FIG. 3 is a view in section of another type of safety valve and a
locking device embodying the invention holding the valve at its
open position;
FIG. 4 is an enlarged view in section of the collet type
fire-responsive locking device shown in FIG. 3;
FIG. 5 is a view in section along the line 5--5 of FIG. 4;
FIG. 6 is a view in section of a still further form of fire safety
valve and locking device embodying the invention;
FIG. 7 is an enlarged fragmentary view in section of a modified
form of fire-safety device on a valve similar to that of FIG. 6;
and
FIG. 8 is a fragmentary view in section of a modified form of the
valve shown in FIG. 7.
In accordance with the invention in one form of fire safety valve
locking apparatus embodying the invention an expandable locking
collet is held by a fusible ring around a locking head on the stem
of a gate valve biased by line pressure downwardly toward a closed
position. In another form of fire-responsive safety locking
apparatus useful with a gate valve, a contractible collet is held
at a normal position by fusible material which melts or weakens
responsive to temperature to permit the collet to contract to allow
the valve stem to move into the collet for shifting the valve to
its closed position. In a still further form of fire safety valve
embodying the invention, a locking cap is threaded by an internally
and externally threaded locking bushing of fusible material holding
the valve stem at a closed position until the locking bushing is
subjected to a predetermined temperature. In a still further form
of valve embodying the invention, the valve is held at its open
position by pressure within a chamber released by a fusible plug
responsive to a predetermined temperature.
Referring to FIG. 1 of the drawings, a gate valve 10 constructed in
accordance with the invention includes a body 11 having flanges 12
and 13 for connection of the valve into a flow line. The valve is
generally similar in structure to the Type X Otis Surface Safety
valve illustrated in and described at page 3832 of the 1968-69
Edition of the The Composite Catalog of Oil Field Equipment and
Services, published by World Oil, Houston, Texas. A piston assembly
14 mounted on the valve body includes a body member 15 having base
mounting flange 20 secured on the valve body 11. The piston
assembly body 15 has a cylinder chamber 21 vented to the atmosphere
through a bleed port 22 at the lower end of the cylinder. A gate
valve 23 is slideably disposed in the body 11 in a pocket 23a for
vertical movement between open and closed positions. The gate valve
has an opening 24 which registers with the flow passage 25 through
the valve body when the valve member is at the open position
illustrated in FIG. 1. The gate valve has a lower stem 30 connected
at its lower end with the gate valve and provided with a piston 31
slideably disposed within the cylinder 21. Suitable packing 32 is
disposed at the base of the body 15 around the lower valve stem to
prevent leakage from the valve body around the valve stem. A ring
seal 33 is supported around the piston 31 to seal within the
chamber 21. The lower valve stem and valve is provided with a
vertical flow passage 34 which opens at its lower end into the port
24 through the valve and communicates at its upper end with a
lateral flow passage 35 provided in an upper valve stem 40
extending above the piston 31. The upper valve stem has a locking
head 41 defined above an external annular locking recess 42 in the
stem. A ring seal 43 is disposed in an external annular recess in
the head of the body 15 to seal around the upper valve stem 40
above the piston 31.
In accordance with the invention, the valve 23 is locked at its
upper open position as shown in FIG. 1 by a fire safety locking
assembly 44 which comprises a locking collet 45 and a fusible
locking ring 50. The locking collet has a base ring 51 from which a
plurality of circumferentially spaced locking fingers 52 entend
upwardly. Each of the locking fingers has an internal locking boss
53 received within the locking recess 42 below the locking head 41
of the upper valve stem for locking the valve stem against downward
movement, FIG. 1. Each of the locking fingers has an external
recess 54 at its upper end generally aligned with the internal
locking bosses 53. The fusible locking ring 50 is received in the
recesses 54 of the locking fingers holding the fingers against
radial expansion. The locking ring 50 is formed of a material which
readily reacts to a predetermined temperature level causing it to
either disintegrate by melting or to weaken sufficiently that it
loses the structural strength to hold the locking collet against
the expansion of its fingers. The locking ring may be made of such
metals as lead, solder, a low temperature melting metal sold under
the trademark Serrocast. Preferably, the melting temperature of the
locking ring 50 is within the range of about 350.degree. to
450.degree. F., as any temperature above this range is going to
provide a dangerous environment to the fire safety valve and the
flow system of which it is a part. The safety ring, of course, may
also be formed of a fusible plastic which has sufficient strength
to resist the normal forces applied to the locking collet while
breaking down either by melting or by reduction of its strength to
permit it to stretch sufficiently at the desired temperature to
release the locking collet.
During normal operation of the valve at its open position as shown
in FIG. 1, the locking collet 44 is disposed around the upper valve
stem 40 with the base ring 51 of the collet resting on the top of
the housing 15 and the collet finger bosses 53 engaged in the
locking recess 42 around the upper valve stem. The locking ring is
positioned around the locking finger heads as shown in FIGS. 1 and
2 preventing expansion of the heads so that the locking bosses 53
prevent downward movement of the valve stem and locking head 41
thereby holding the valve at its upper open position. The cylinder
21 is exposed to atmospheric pressure through the bleed port 22
below the piston 31 while line pressure within the flow passage 25
of the valve is communicated upwardly through the flow passage 34
in the valve stem and the lateral passage 35 above the piston so
that line pressure is within the cylinder 21 above the piston 31.
This line pressure, being greater than the atmospheric pressure
below the piston, urges the valve stem and valve 23 downwardly
against the holding force of the fire safety valve lock 44. If the
valve is subjected to fire or is in sufficient proximity to a fire
to raise the temperature at the locking ring 50 above the desired
predetermined value, the ring 50 melts, or if a plastic, loses its
structural strength to the degree that the downward force of the
line pressure above the piston 31 overcomes the collet camming the
collet locking bosses outwardly thereby releasing the locking head
41 on the valve stem so that the line pressure above the piston 31
forces the valve stem downwardly moving the valve member 23 to its
lower closed position at which the port 24 through the valve member
is below the flow passage 25. The nature of the structure of the
valve 23 is such that it is forced to the downstream side of the
valve member pocket 23a in the valve body sealing against the
surface of the pocket on the downstream side around the opening 24
precluding flow past the valve member, while on the upstream side
of the valve there is sufficient tolerance to permit upstream line
pressure to continue to be communicated up through the valve stem
flow passage 34 above the piston 31 to hold the valve at its lower
closed position. When the heat or fire condition no longer exists,
the valve may be returned upwardly to its open position by use of a
suitable pulling tool, not shown. The locking collet is reset
around the locking head of the valve stem and a new locking ring 50
installed around the heads of the collet fingers to again hold the
valve releasably locked open and responsive to temperature
conditions for again closing in the event that heat conditions
raise the temperature in the vicinity of the valve as above
described.
FIG. 3 illustrates a similar type of valve 60 which is locked at
its lower open position and movable upwardly to a closed position.
The valve 60 has a body 61 provided with a flow passage 62 and
suitable flanges 63 and 64 for connection of the valve in a flow
line. A valve 65 having an opening or port 70 is movably disposed
in a valve pocket 71 of the valve body for movement between a lower
open position as shown in FIG. 3 and an upper closed position, not
shown. The valve has a cylindrical valve stem 72 which extends
upwardly into a locking assembly housing 73 supported on the valve
body by an integral flange 74. A suitable seal assembly 75 disposed
in the housing 73 around the valve stem seals against leakage along
the valve stem from the valve body. A heat responsive safety
release assembly 80 embodying the invention is releasably disposed
in the housing 73 holding the valve stem 72 at the lower end
valve-open position as shown in FIG. 3. The safety assembly is held
in the housing by an annular retainer cap 81 having an internal
annular locking surface 82 for holding the assembly at its locking
position. The lower end of the cap 81 along with the inner surface
of the housing 73 below the cap 81 defines an internal annular
collet release recess 84 which performs a releasing function when
the lock assembly 80 responds to temperature and is forced upwardly
by the valve stem.
The fire safety assembly 80 comprises a collet 85 having integral
longitudinal fingers defined between downwardly opening
circumferentially spaced longitudinal slots 90 and alternate
upwardly opening circumferentially spaced longitudinal slots 91,
FIG. 5, whereby the collet is expandable and compressible at both
its upper and lower ends. The collet finger upper end portions have
external locking bosses 92, while, similarly, the lower collet
finger end portions have external locking bosses 93. The upper
collet finger end portions are provided with internal recesses 94
aligned to define an internal annular recess in the head of the
collet through which is disposed a fusible locking disc 95 for
holding the upper end portion of the collet against compression
until a predetermined temperature level is reached which the
locking disc melts or otherwise is weakened sufficiently to no
longer have the structural strength to hold the upper end portion
of the collet against compression. It will be recognized that, if
desired, instead of a locking disc an internal annular ring, such
as the ring 50, may also be used disposed through the slots 94 to
hold the collet against compression. The lower free end portions of
the collet fingers have internal locking surfaces 100 or inner
bosses 101 which are engageable with a tapered upper end portion
72a of the valve stem, see FIG. 3. The upper end portions of the
collet fingers have sloping locking surfaces 102 engageable with
the internal annular licking shoulder 82 in the retainer cap
81.
The operative position of the fire safety lock assembly 80 is
illustrated in FIG. 3 at which the assembly releasably holds the
valve member 65 at its lower open position to permit flow through
the valve passage 62. The lower locking collet head surfaces 100
engage the locking shoulder surface 72a on the upper end of the
valve stem. The lower collet locking finger bosses 93 are confined
at the normal radial positions shown in FIG. 3 by the internal
housing surface defining the lower bore 73a of the housing 73 below
the collet release recess 84. The internal locking shoulder 82 of
the retainer cap 81 is engaged by the locking surfaces 101 on the
upper end of the collet holding the collet against upward movement.
The line pressure within the valve flow passage 62, effective
across the sealed area of the valve stem defined by the seal 75,
exceeds the atmospheric pressure on the stem above the seal 75
whereby the valve stem and valve 65 are biased upwardly by line
pressure toward a closed position. So long as the temperature
remains below the level at which the disc 95 melts or substantially
weakens, the locking assembly 80 holds the valve at its open
position as shown in FIG. 3.
When the valve 60 is exposed to a temperature above the desired
predetermined level, either by direct flame or being in the
proximity of a fire, the safety disc 95 either disintegrates by
melting or the strength of the disc is sufficiently reduced that it
no longer is capable of supporting the upper end portion of the
fingers of the collet 85 at their normal positions against the
inward camming effect of the retainer cap surface 82. The upward
force of the upper end of the valve stem against the lower collet
surfaces 100 urges the collet upwardly so that the coaction between
the upper collet surface 102 and the locking shoulder 82 of the
retainer 81 cams the upper end portions of the collet fingers
inwardly. The collet fingers are forced upwardly and compressed
inwardly past the locking surface 82 and outwardly through the
upper end of the retainer. Simultaneously, the upper valve stem end
surface 72a cams the lower ends of the collet fingers radially
outwardly expanding them into the cam release recess 84 whereby the
valve stem is released to move upwardly into the lower end of the
collet permitting the valve to move to the fully closed position.
Line pressure will continue to be applied to the valve and stem
holding the valve upwardly at the closed position. The valve 65 is
similar to the valve 23 of FIG. 1 and seals on the downstream side
against the downstream surface of the valve pocket 71 with
sufficient tolerance at the upstream side of the valve to permit
line pressure to be applied over the valve and stem holding the
valve at the upper position.
The valve 65 is reset by use of a suitable closing device, not
shown, including a probe or rod for engaging the upper end of the
valve stem to force it to back downwardly reopening the valve. The
locking collet is removed from the housing 73 by unscrewing the
retainer cap 81 and lifting the collet upwardly. The fire safety
locking assembly 80 is reset by inserting a new safety disc 95 into
the upper end of the collet by expansion of the collet fingers
sufficiently to manipulate the disc into the recesses 94. After
replacement of the safety disc, the collet is reinserted to the
position shown in FIG. 3 and the cap 81 is reengaged in the top of
the housing.
A still further form of fire safety valve 110 is illustrated in
FIG. 6. The valve 110 is normally a pressure responsive valve
controllable from a remote location by fluid pressure. The valve
has a body 111 provided with a flow passage 112 and flanges 113 and
114 for connection into a flow line. Flow through the passage 112
is controlled by a gate valve 115 having a part 120 and connected
with a valve stem 121 which extends upwardly into a pressure
chamber 122 provided within a vessel 123 secured on a base 124 by a
lock ring 125. A valve stem guide flange 130 is formed integral
with a base 124 and provided with a ring seal 131 which seals
around the valve stem within the guide flange. The base 124 is
secured by a plurality of bolts 132 to the valve body 111. A coil
spring 133 is confined between the plate 124 and an annular piston
134 rigidly secured, as by welding, on the valve stem in the
chamber 122. A ring seal 135 around the piston seals within the
cylinder chamber. The cylinder chamber is vented to the atmosphere
below the piston by a bleed port 140. An upper end portion of the
valve stem 121 extends through an externally threaded nipple 141
formed on the head end of the vessel 123. A ring seal 142 in an
internal annular recess of the nipple 141 seals around the stem 121
so that pressure may be maintained in the cylinder 122 above the
piston 134. A conduit 143 containing a valve 144 is connected into
the head of the cylinder 123 to provide fluid pressure for holding
the piston 134 downwardly against the spring 133 to maintain the
valve 115 at the open position shown in FIG. 6. A valve similar to
that of FIG. 6 is an Otis Type U Surface Safety Valve illustrated
at Page 3834 of the Composite Catalog of Oil Field Equipment and
Services, supra. The conduit 143 may be connected to a controllable
source of fluid pressure which reacts responsive to any desired
condition, such as excessive heat which would relieve fluid
pressure within the chamber above the piston to allow the spring to
lift the valve to its closed position.
In accordance with the invention, the valve 115 is locked at its
open position by an internally threaded cap 145 secured on the
nipple 141 over the upper end of the valve stem 121 by a fusible
internally and externally threaded bushing 150. The bushing is
provided with a lower external annular end flange 151 for gripping
the safety bushing when threading it on the nipple. So long as the
fusible safety bushing is intact, the cap 145 engages the upper end
of the valve stem 121 holding the valve open in such a manner that
it is closable only when the valve is enveloped in a fire or
sufficiently close to a fire that the flow system including the
valve is endangered. The heat from such a fire or nearby fire melts
the fusible bushing or sufficiently weakens it that the force of
the spring 133 can lift the valve stem to close the valve. The
upper end of the valve stem forces the cap 145 off the nipple 141.
It will be apparent that coincident with the release of the valve
stem by the fusible safety bushing, the fluid pressure within the
cylinder 122 above the piston 134 must also be reduced to permit
spring action and line pressure to close the valve. The fire safety
system on the valve 110 is generally used only under special
operating conditions of the valve where it is desired that the
valve be restrained against closing in the event of a malfunction
of the fluid control system. An example of such an operating
condition is encountered when the valve is used as a master valve
in a well head and wireline operations are being carried out in the
well through the well head. In this situation, if the valve were
permitted to suddenly close responsive to some failure or
malfunction of the pressure control system of the valve supplying
the fluid into the chamber 122, the valve would suddenly close
cutting the wireline passing through the valve flow passage 112 and
the port 120 in the valve 115. Such an accident could necessitate
substantial expense in retrieving the wireline and equipment
connected thereto. While it is desirable under such circumstances
to protect the valve against a control fluid pressure malfunction,
it is further desirable that in so protecting the valve it not be
restrained against closure in the event of fire. Thus, during
wireline operations the valve is locked open by the cap 145 secured
on the nipple 141 by the fusible safety bushing 150. When a
wireline operation is completed and the wireline is withdrawn
through the valve, the valve is returned to normal fluid pressure
responsive operation by unscrewing the locking cap 145 and the
fusible bushing from the nipple on the cylinder body.
A modified form of pressure responsive valve 160 is illustrated in
FIG. 7. The valve 160 is similar to the valve 110 of FIG. 6 in
structure and operation. The body of the valve 160 may be identical
to the valve body 111 with the base portions of the cylinder body
161 of the valve 160 being identical to that of the body 110. The
valve stem 121a of the valve 160 is secured to and terminates in a
piston 134a which carries an external ring seal 135a for sealing
around the piston in the cylinder of 162 of the housing 161. A
spring 133a biases the piston upwardly to lift the valve member of
the valve to a closed position in the event of failure of pressure
within the cylinder above the piston. Control fluid pressure is
communicated through a conductor 163 containing a valve 164 into
the cylinder chamber from a remote fluid control unit, not
shown.
In accordance with the invention, fire safety assembly 170 is
secured through the head of the cylinder body 161 to relieve the
fluid pressure in the cylinder in the event of fire or excessive
heat exposure. The safety device 170 includes an externally
threaded nipple 171 provided with a fusible core 172 extending the
full length of the nipple within the longitudinal bore of the
nipple. Upon destruction and thus expulsion of the core from the
nipple, the cylinder chamber 162 is communicated through the bore
of the nipple to the atmosphere. In operation, the valve 160 is
normally held at its open position by the pressure of the control
fluid communicated into the cylinder chamber through the conductor
163. If the valve is subjected to excessive heat, the fusible plug
172 of the nipple melts thereby releasing the control fluid
pressure from the cylinder above the piston 134a permitting the
spring 133a and line pressure to lift the piston to close the
valve. A plurality of plugged nipples 171 may be circumferentially
spaced around the top of the vessel 161 to provide a safety device
near a fire approaching from any direction around the valve.
A still further form of valve 180 embodying the invention is
illustrated in FIG. 8. The valve 180 is similar to the valve 160 of
FIG. 7 and includes certain identical parts denoted by the same
reference numerals as used in FIG. 7. The general structural
arrangement of the valve is similar also to the valve 110 in FIG.
6. The cylinder body 181 has a nipple 183 formed integral with its
top. The nipple is provided with a stepped bore comprising a first
upper bore portion 184 and a connecting reduced lower bore portion
185 opening into the chamber 182 of the cylinder. The chamber 182
is initially charged with a suitable fluid to a pressure sufficient
to hold the piston 134a at a lower valve-open position and the bore
portion 184 is filled with a fusible plug 190 sealing the fluid in
the chamber. The ring seal 135a prevents leakage past the piston.
When the plug 190 is heated to the breakdown temperature of the
fusible material, the plug is expelled from the nipple bore
releasing the fluid pressure in the chamber allowing the spring
133a and line pressure to lift the valve to a closed position. The
valve may be opened and reactivated by repressuring the chamber and
replacing the fusible plug 190. If desired, a plurality of the
nipple-fusible plug safety devices may be used in the cylinder so
that the valve is sensitive and responsive to more localized heat
sources around the valve.
It will now be seen that a new and improved form of fire safety
valve has been described and illustrated for use in flow lines
included in such apparatus as well heads, pipe lines, and the like.
Fire safety valves embodying the invention in one form utilize a
mechanical lock releasable responsive to a predetermined
temperature level, while in other forms, the safety device
comprises temperature responsive pressure release means, both
utilizing fusible material for releasing a valve for closure when
overheated. The mechanical form of the apparatus is applicable to
gate valves which close downwardly and also to those which close
upwardly. In the first instance, the device includes an external
collet arrangement which holds the valve against downward movement
until overheated, while in the second arrangement an internal
collet is utilized to hold the valve against upward movement until
overheated. The new and novel safety devices are not susceptible to
accidental triggering so that they release only in response to
excessive temperature conditions.
* * * * *