Note: Descriptions are shown in the official language in which they were submitted.
~Z8~130
~ lis invention relates to a fluid control valve,
particularly though not exclusively of the butterfly or
ball type, which can be made firesafe.
Con~entional firesafe fluid control valves typically
comprise a seat including a flexible ring with which a
val~e member is engageable to prsvent fluid flow through
the valve, the flexible ring being made of a soft material
such as P.T.~.E. In the event of the flexible ring being
destroyed by fire, the valve member is arranged to contact
a metallic lip on the seat to maintain the valve shut.
However, in order to satisfy the relevant British
Standard 5146, close contact must be ensured between the
valve member and the metallic lip, which poses very large
manufacturing problems. These problems become more acute
in larger valves, since the permissible clearance between
the valve member and the metallic lip becomes less as the
size of the valve is increased. In addition, where the
valve is of the butterfly or ball type wherein there is
angular movement of the valve member relative to the seat,
problems arisa due to "pick-up" or galling of the
co-acting surfaces of the valve member and the metallic
lip .
It is an object of the present invention to pro~ide
a fluid control valve which is capable of satisfying the
requirements of the aforementioned British Standard 5146,
and which obviates or mitigates the above-described
problems. In this connection, references to British
Standard 5146 are intended to mean BS.5146:1974 both as
originally drafted and as proposed to be amended at the
date of filing of thisapplication.
According to the present invention, there is provided
a fluid control ~alve comprising a body having a through
passage, a valve member mo~able between a first position
,~
~Z~3~3(~
in which it permits fluid flow through the passage and a
second position in which it prevcnt3 such fluid flow, a
flexible ring which nor~ally pr~Yides a seal between the
body and the valve member when in its second posi~ion, and
a further ring of high temperature, non-metallic material
which is arranged to pro~ide a seal between the body and the
~alve member in its second position in the e~ent of failure
of the flexible ring so as to prevent fluid flow through
the passage.
The non-metallic ring is preferably intended to be
resistant to temperatures of at least 600 C. The material
of the non-metallic ring can a~so be inherently non-galling:
for example, the non-metallic ring can be made of graphite.
Advantageously, a seat surrounds the passage in the
body and incorporates a metallic mounting ring having a
sùrface which is normally spaced from the valve member in
its second position, but which is arranged to be engaged
thereby in the e~ent of failure of both the flexible ring
and the non-metallic ring so as to restrict the flow of
fluid through said passage. The fle.~ible ring and/or the
non-metallic ring are preferably incorporated into the seatJ
in which case the mounting ring advantageously ha~ an
annular recess therein into which the non-metallic ring is
compression-formed. In one particular arrangement, the
mounting ring is composed of two annular parts which are
axially engaged so as to retain the non-metallic ring
therebetween: in this case, one of the annular parts can be
interposed between the fle~ib~e ring and the non-metallic
ring.
The flexible ring is preferably made of flexible
resilient fluorocarbon synthetic resin material, such as
P.T.~.E., and is preferably also subject to cold flow.
~Z~Q30
The valve may take the form of a butterfly valve in
which the valve- member is a disk mo~n~2d on the body so
as to be pivotable about an axis transverse to the a~is
of the through passage. DastrabLy, the disk has a part-
spherical peripheral surf`ace which engages the flexible
ring when the valve member is in its-second position, and
the pivot a~is is offset from both the plane of the dis~
and the axis of the through ?a~sage, for e~ample in the
manner described in ~ritish Patent ~o. I290325. In Ihis
case, the flexible ring is preferably of the type ~isclosed
in British Patent No.1305554.
Alternatively, the valve may take the form of a ball
valve in which the valve member is a ball mounted in the
body so as to be rotatable about an axis transverse to the
axis of the through passage, the ball having a through
bore which communicates with the through passage in the body
when the valve member i9 in its first position. In this
case, two seats are advantageously provided respectively
surrounding parts of the through paqsage on oppoqite sides
of the ball, each seat incorporating a flexible rin~ and a
high-temperature, non-metallic rin~.
Embodiments of the present invention will now be
described, by way of e~a~ple, with ref`erence to the
accompanying drawings, in which:-
Figure 1 is a sectional side view of a fluid controlvalve according to the present invention, in the form of
a butterfly valve;
Figure 2 is an enlarged view of part of the valve
shown in ~igure 1, illustrating in particular a seat
thereof;
~Z8(~30
Figure 3 is a similar view to ~lgure 2 of an
alternative form of seat; and
Figure 4 is a sectionai side view of a flui.d oon~rol.
valve according to the present invention, in the form o
a ball valve.
Referring first to Figures 1 and 2, the butterfly
valve shown therein comprises a body 10 having a through
passage 11, and a seat 12 which is secured to one a.~ial
end of the bocly 10 and which surrounds the passage 11. The
seat 12 is composed of a metallic ring 13 ~hich supports
two further rin~s 14 amd 15. The ring lJI is made of
fle~ible resilient fluorocarbon synthetic resin mater;al
(such as PoT~F~ ) wllich ls suhject to cold flo~, for a
purpose which will be explained la-ter. In the particul2-
embodiment illustrated, the flexible ring 1~ is Or the
type described in British Patent ~o 1305554, I`he ring
15 is made of a high-temperature, non-metallic material
which is non-galling; e.Yamples of such a material are
"Gl~A~OIL" ~Re~istered Trade ~larlc)~ a form of graphi.te
marketed by Union Carbide Corporation and "GRAh~`TITE",
a form of graphite marketecl bv Crane Pac~in~ Ltd. The
non-metallic ring 1; is receivecl in an annular resess 16
in the mounting ring 13 ~hictl has unclercut surfaces
providing protection against the ring 15 bein~.r hlo~n
o~lt by the pressure of the fluid flot~ing th.-ou~h the
passage 'I 'I ~ the rin~ 15 being compression-formecl withi.n
the recess 16.
A val~e member in the form of a disk 17 hav.ing a
part-spherical peripheral surface 1~ ~s mountecl in t~e
body 10 so as to be pivotabl- about an a~is 19
perpendicular to the a~is of the passage 11, the disk 17
being pivotable between a first position ¦shown in broken
lines i~ Figure 1) in which it permits f`luid flow
through the passage 11 and a second positior.
(shown in full lines in ~igure 1) in which
l~Z8(~30
_ 6 --
the surface 18 engages the flexible ring 14 so as ~o
prevent such fluid flow. In its second position, the disk
17 is also in light contact with the non-metallic ring 15.
~he pivot a~is 1Q is sffset ~roln bo~h ~he piane of t;he
disk 17 and the axis of the passa2e 11, and the centre of
the part-spherical surface 18 ies on the a.~is of the
passage 11 when the disk 17 is in its second position.
This arragement causes the surface 18 to lift away from
the flexible ring 14 when the disk l7 is pivoted out of
its second position, so that the valve does not rely on an
interference fit between these parts to achieve fluid-tight
closing,
Because the fle~ible ring 14 is subject to cold flow,
engagement thereof by the disl~ 17 effectively cold-forms
the ring 14 to a reguired shape, sufficient resilience
remaining to urge the co-acting surfaces of ~he ring 14
and the disk 17 into close contact. Such cold-forming of
the ring 14 is assisted by its shape, and reference is
directed to the aforementioned British Patent ~o. 130554
for a further explanation of this.
In the event of the fle.Yible ring 14 being destroyed
by fire or otherwise failing, the disk 17 when in its
second position will engage closely the non-metallic ring
15 so as effectively to prevent fluid flow through the
passage 11; more particularly, the leaka~e rat~ of the
non-metallic ring is sufficiently low to satisfy British
Standard 5146, In the event that the non-me~allic rlng
15 also fails, for example due to mechanlcal damage, the
disk 17 when in its second position will engage a surface
20 (see Figure 2) on the metallic mounting ring 13 which
is normally spaced from the disk 1~, thereby restricting
the flow of fluid through the passage 11.
In order to prevent the escape of fluid to atmosphere,
an annular seal 20a is provided between the body 10 and
the metallic ring 13 so as to surround the passage 11 The
seal 20a is made of graphite or graphite-based rnaterial and
is compression formed into a suitably shaped recess in ths
metallic ring 13.
The valve described above is designed for fluid flow
2~3~3
therethrough only in the direction of arrow 21 in Figure 2,
since fluid flow in the opposite direction would tend to
dislodge the non-metallic ring 15 from the mounting ring 13
in the event that the flexiblc ring 14 fails. Figure 3
illustrates a modification of the valve in ~hich bi-direct-
ional fluid flo~ is permitted. In this modification, the
metallic mounting ring 13 is composed of two annular parts
22 and 23 which are axially engaged and which retain the
non-metallic ring 15 therebetween, one of the annular parts
23 being interposed between the ring 15 and the flexible
ring 14. The part 23 is also disposed between the part 22
and the body 10 so that the non-metallic ring lS is still
retained between the parts 22 and 23 if the flexible ring
14 fails. The non-metallic rin2 15 is compression-formed
in a recess 24 in the annular part 22 using a die whose
configuration matches that of the annular part 23.
Referring now to Figure 4, the ball valve shown
therein comprises a metallic body 30 formed from two parts
31 and 32 which are secured together by bolts 33. The
body 30 has a through passage 34 formed therein which
passes through a valve chamber 35 irl which a valve member
in the form of a ball 36 having a through bore 37 is
housed. The ball 36 can be rotat~d by mean~ of an operating
member 38 about an axis 39 perpendicular to the a~is of the
passage 34 between a first position in which the bore 37
communicates with the passage 34 so as to permi~ fluid ~lo~
through the valve (as indicated ir~ broken lines), and a
second position in which the bore 37 doe~ not comlnunicate
with the passage 34 ~as indicated in $~1 lines), thereby
preventing fluld flow through the valve.
Two seats 40 are disposed in the valve chamber 35 and
respectively surround parts of the passage 34 on opposite
sides o~ the ball 36 Each seat 40 incorporates a r ng 41
made of` flexible resilient fluorocarbon synthetic resin
material, such as P.T ~ E., which is sealingly engaged
with the external surface of the ball 36, and a ring ! 2
made of a high-~emperature, non-galling, non-metallic
- ~2~30
material which islighly contactadbv the ball 36. As
in the ernbodiments of F`igures 1 to 3, each non-metallic
ring 42 is made of graphite-based material. Fach ring
42 is received in a respective annular recess 43 in the
body 30 which is so shaped as to protect the ring from
blowing out under the pressure of the fluid flowing
through the valve. Adjacent each recess 43, the body 30
is shaped so as to form an annular lip 44 which is spaced
from the external surface of the ball 36,
In the event of failure of the fle~ible ring 41 of
either seat 40, the ball 36 will closely engage the
respective non-metallic ring 42 thereby maintaining
effect~ive fluid-tight closure of the valve. In the event
of the non-metallic ring 41 failing also, the ball 36 w~ll
engage the respective lip 44 so as to restrict the flow
of fluid through the valve,
In all of the above-described embodiments, the high
temperature properties of the non-metallic rings 15,42
enable the valve to remain effectively fluid-tight when
shut even if the fle.~ible rings 14,41 are destroyed by
fire. Moreoever, since the non-metallic rings 15,42 can be
compression-formed, it is comparatively simple to make
them iIl a shape which will ensure close contact with ~he
valve member so as to maintain fluid-tight closing of
the valve, ~urthern1ore, even if the valve is subsequently
damaged causing failure of the non-metallic rings 15,42
the mounting ring 13 in Figures 1 to 3 and the lips 44 in
~igure 4 still maintain the valve in a low leakage
condition, Thus, the valves are able to satisfy the
requirements of Bntish Standard 5146,
Because the valve has a high temperature capability
in a non-o.~idising environment, it is particularly suited
for use in the field of petrochemicals,
