CA1146142A - Seal assembly - Google Patents

Abstract

ABSTRACT

A bi-directional valve comprising a valve body with a recess having a planar surface and a retaining ring having a recess, with the recesses forming a chamber therebetween having an axial centerline parallel to the planar surface and sealing means in said chamber for engagement with a closure means. The sealing means comprising an integral seat ring and a resilient back-up means. The seat ring includes an outer portion, an offset hinged L-shaped portion having a cavity therein to position said back-up means, and a substantially rectangular inner portion having a shoulder ring portion on each side thereof.
Pressurization of said sealing means results in substantially perpendicular application of forces of said back-up means and the fluid pressure onto the closure means.

Description

SEAI, ~SSEMBLY

BACKGROUND AND SUMMARY OF T~E INVENTION

This invention relates to bi-directional valves, and ~in particular to a new sealing means construction having applications in butterfly valves. Butterfly valves have many advantages over other types of valves in fluid flow regulation, mo~t notable being ].ower cost to the manufacturer, quickness o~
opening and low restriction to fluid flow when fully open.
Howeverl these valves generally have been limited to low pressure applications because of their inability to seal tightly at high pressures. In some prior art valves, the seal~, are located in grooves in the valve body which often become :: :
dislodge&~when the~valve is open thereby permittiny fluid to flow~around the seal. ~In other prior art valves, high pressure fluid~may leak through the vaLve by flowing ~etween the valve body and seal; uhile in many other prior art valves~ contact between~the~disc and~seal must be made~so tight in order to prevent leakage that opening the valve, particularly large diameter valves, requires a large torque. Furthermore, in several prior art valves used in high pressure and/or high temperature applications, the seat ring or sealing means lo,es the desired preloading on the seat ring sealing face as the se~at ring expancls~. In still other ~loating seal valves, high pressure fluid, which enters the recess when the valve is closed, cannot escape when the valve is opened, thus causing the seal to blow out ~ : .

In other floating seat valves, an attempt is made to reduce the torque required to open and close the disc, while improving the retention o the seat ring sealing face as the seat ring expands by employing indirect or partial application of resilient means and fluid pressure forces on the sealing face.
It is an object of the present invention to provide an improved bi-directional valve which will neither leak nor blow out under high pressures and which is operable with a relatively low torque.
A further object of this invention is to provide a reliable, exceptional long life, relatively inexpensive and easily rep]aceable and serviceable valve seat.
It is still a further object of this inventlon to provide a bi~directional valve having improved sealing means which ~ully utilizes direct application of resilient means and fluid pressure forces on the sealing face.
The bi-directional valve herein comprises a valve body having a flow passage therethrough with a recess in proximity to the passage, the recess having a planar surface with a groove therein. A retaining ring surrounds the passage and is detachably affixed to the valve body. The ring has a recess therein, the recess having a surface with a groove therein.
A chamber, open to the passage, is formed between the recesses.
The chamber has an axial centerline parallel to the planar surface. A closure means is pivotally positioned in the passage between an open and a closed position to allow or prevent, respectively, fluid flow therethrough. The closure means has a peripheral land adapted to engage a sealing means.
The sealing means includes an outer portion adapted to be secured between the valve body and the retaining ring; an offset hinged L-shaped portion integral with the outer portion, ~ -2-~ ~3 the L-shaped portion having a cavity therein adapted to recei~e a resilient back-up means; a substantially rectangular inner portion integral with the L-shaped portion, the inner portion having a shoulder ring portion on each side thereoE, with the shoulder ring portion on one side projecting into the groove of the valve body and the shoulder ring portion on the other side projecting into the groove of the retaining ring;
and a resilient back-up means positioned in the cavity. When the sealing means is pressurized by fluid from either side thereof upon closing of the closure means, the parallel relationship of the planar surface and the axial centerline causes the back-up means and fluid directed on the inner portion -to apply their combined forces substantially perpendicular to the peripheral land to effect sealing of the valve.
Fig. 1 is a plan view, in section, of a butter~ly valve utilizing the seal of this invention with the closure means shown in solid lines in the closed position~ and in broken lines in the open position.
Fig. 2 is an enlargement of the seal of Fig. 1 with the seal unloaded. Such a condition would occur when the valve is open permitting flu1d flow through the valve.
Fig. 3 is an enlargement of the seal of Fig. 1 with the seal in a preloaded condition. Such a condition would occur when the closure means is closed and no line pressure is applied.
Fig. 4 is an enlargement o~ the seal of Fig. 1 with the seal in a preloaded and pressurized condition. Such a condition would occur when the closure means is closed and pressure differential across the valve forces line fluid into ,~
~. , . : . , ,, .. ~ . . . . . .

the channel on one side of the sealing means.
Fig. 5 is an enlargemen~ of the seal of Fig. 1 with the seal in a preloaded and pressurized condition. Such a condition would occur when the closure means is closed and pressure difEerential across the valve Eorces line fluid into the channel on the other side of the sealing means.

:
Referring to the drawings and more particularly to ;Figure 1, a valve, generally represented by re~erence numeral 10, having a flow passage 12 in valve body 14 is shown located in conduit 18. Valve 10 may be secured in the conduit by welding, bolted flanges, or other common way. A valve closure :
means, such as valve disc 21 having curvilinear peripheral land , 22 is shown in solid lines in the closed position and in broken lines in the open pGsition. Disc 21 is secured to stem 16 which protrudes through valve body 14 and has a handle or other means (not shown) attached thereto in the usual manner to provide an axis about which disc 21 may be rotated to open or close the flow passage 12. Sealing means 30 includes seat ring 31 and resilient back-up means, such as spring 50, and is disposed between valve body 14 and retaining ring 40 which is detachably connected to valve body 14 via fastene~ 42, as shown. Since the axis of rotation of disc 21 does not coincide with a centerline through seat ring 31, there is eccentric movement of the disc relative ~to the seat ring causing a faster break-away between disc 21 and seat ring 31 than would otherwise result if the disc and seat ring centerlines ~ A -coincided. ~owever, the subjecl invention may be practiced with coincidence of the disc ax:is of rotation and the seat rincJ
centerline.
Referring to Figure 2, valve body 14 has a recess therein formed by planar suraces 72 and 72A which are separated by first groove 76 therebetween, and second groove 78 which is adjacent surEace 72n Retaining ring 40 has a recess therein comprising surfaces 82 and ~2A disposed in juxtaposition to surfaces 72 and 72A, respectively, and separated by groove 36 therebetween, first surface 88 continuvus of surface 82 in a plane normal thereto, and conf.ining surface 89 continuous of surface 38 in a plane substantially normal thereto.
The aforementioned recesses of valve body 14 and retaining ring 40 de:Eine chamber 60 which is adapted to receive sealing means 30. It should be noted that chamber 60 is so disposed that its axial centerline is positioned parallel to planar surface 72 of valve body 14.
: :Sealing means 3~is comprised of seat ring 31, made of heat and chemically resistant material such as fluorocarbon, urethane or elastomeric polymers/ and resilient back-up means, such as a metallic garter-type spring 50. Seat ring 31 includes in~egrally connected outer portion 32, hinged L-shaped portion 33, and inner portion 34. When the disc is in open position and wlth retaining ring 40 secured tv valve body 14, outer portion 32 is sized, preferably, so as to be fixedly reta:ined in place in an area defined by second groove 78 and confining surEace 39. The volume of mass oE outer portion 32 is sized larger than the~volume of material that can be .

contained between second yroove 78 and confining surfacc ~9, so that, the outer port:ion becomes compressed theLein Eorming a fluid leak-tight seal around its periphery. To assure fi~:ed retention oE the outer portion therein, the area is, preferably, configurated to have narrowes~ extent along line AA' formed by joining the points of contact of surface 88 to confining surface 89 and of planar surface 72 to second yroove 78. ~hough this embodiment is preferred, outer portion 3~ can be of any suitable configuration and retained ~y any suitat~le means.
;~ ~ Por-~ion 33r integrally joined to outer portion 32, contains cavity 55 therein, which i5 adapted to receive spring 50:which exerts counter or supportive forces to structure in contact thereto, to prevent the collapse of portion 33 when pressure diferential i.s exerted on the retaining ring sicle o~
seat ring 31. Portion 33 is freely suspended from portion 32 in chamber 60, so that, pressure differential being exertecl on : either side of se t riny 31 causes hinge-like movement of portions 33 and 34 about line AA'. Portion 33 has surface '31 the.reon, which is, preferably, of cut hack or chamfered configuration thereby permitt.ing a greater unoccupied portion of chamber 60, thus assuring unimpeded hinge-like movement of : portions 33 anrl 34 ahout line ~A'~ Portion 33, though resilient and flexible, is of non-conical L-shaped confiyuration which upon loadin~ via fluid pressure assumes a radii arc shape.
Inner porti.on 34 r :integral to portion 33l is substantially of rectangular shape, in section, h~ving sealillg surface 36. Inner portion 34 has integral shoulder ring ' ~4~

portions 35 and 37 which project into grooves 86 t 76, respectively, for controlling the amount of projection of eat ring 31 into passage 12, and preventing blow out of seat r.in(3 31 when disc 21 is opened or closed. Sealing surface 36 may be spherical, conical o~ other similar shape, and portions 35 and 37 are, preferably, of trapezoi.~al configuration, in section.
Since chamber 60 is wider than 2ortions 33 and 34, channels 100, 101 are provided between portions 33, 34 and the recesses of ring 40 and valve body 14/ respectively, facilitating insertion of seat ring 31 into chamber 60, pressurization and depressurization of cavity 55 and freedom of movement of portions 33 and 34 during valve operation.
~ eferring to Figure 3, in its closed, unpressuri~ed condition, disc 21 ~edges land 22 into sealing surface 36 causing It to expand o~utwardly creating interference load ].10.
Channels lOO and 101 are approximatel~ of equal width.
In Figure 4, fluId under pressure is directed into channel lQ0. Fluid pressure component:l20 acts normally on portions~33 and 34 causiIlg theIr pivotal movement about line AA'. Spring 50, while acting t.o prevent the collapse of portion 33, moves with portion 33 until fully compressed against planar surface 72. The movement of portions 33 and 34 results in radial enlargemerIt of channel 100, and abutting engagement of inner portion 34 ~and shoulder ring portion .37 with surface 72A and groove 76, respectively, preventing further displacement of inner portion 34.
Fluid pressure component 122 acts radially on portion :33 forcing .it and spring(50 downward, transmitting through , ~
: ~ inner:portion 34 d.irectly onto sealing surface 360 Due to the parallel:reIationshIp o pla~ar surface 72 and centerline LC of chamber ~0, full fluid pressure compont~llt 122 and undef:lect~]
spring force component 51 is exerted dir~ctly onto surEace ::3G.
An improved dynamic loading of sealing surface 36 is provi.ded by the direct applications of these forces and interference load 110 thereon resulting in substantially perpendicular application of these forces onto land 22.
In Figure 5, fluid under pressure is directed into channel 101. Fluid pressure component 130 acts normally on inner portion 34/ and cavity 55 of portion 33 causing pivotal.
movement of portlons 33 and 34 about line AA', radial enlargement of channel 101, and engagement of surface 91 w.i~:h the recess of ring 40. Inner portion 34 and shoulder ring portion 35 are in abutting enga~ement with surEace ~2A al~d groove 86, respectfully.
Fluid pressure component 130 can be broken down for purposes of explanation, into partial force components 56, ';7 and 58. Surfaces ~2, 88 act as constraints for portion 33 under the loads of part.ial force componellts 56, S8, respectfully. Partia:l force component 57, as well as undefIect.ed spring force component 51, is transmitted through inner portion 34 directly onto surface 3~, providing by their direct applications and interference load 110, an improved dynamic loading of surface 36 resulting in substantially perpendicular application of these Eorces onto land 22.
Although a certain embodiment has been described and illustrated,.modificcltion may be made herein, as by adding, combining or subdividing parts or by substituting equivalents or by applying the invention to other types of valves or mechanisms while retaining advantages and ben~fi~s of the invention, which itself is define~ in the followirlg claims.

Claims (6)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A bi-directional valve comprising:
A. a valve body having a flow passage therethrough with a recess in proximity to the passage, the recess having a planar surface with a groove therein;
B. a retaining ring surrounding the passage and detachably affixed to said valve body and having a recess therein, the recess having a surface with a groove therein, C. a chamber open to the passage and formed between the recesses, said chamber having an axial centerline parallel to the planar surface;
D. a closure means pivotally positioned in the passage between an open and a closed position to allow or prevent, respectively, fluid flow therethrough, said closure means having a peripheral land adapted to engage a sealing means;
E. a sealing means including:
an outer portion adapted to be secured between said valve body and said retaining ring;
an offset hinged L-shaped portion integral with said outer portion, said L-shaped portion having a cavity therein adapted to receive a resilient back-up means;
a substantially rectangular inner portion integral with said L-shaped portion, said inner portion having a shoulder ring portion on each side thereof, with the shoulder ring portion on one side projecting into the groove of said valve body and the shoulder ring portion on the other side projecting into the groove of said retaining ring; and, a resilient back-up means positioned in the cavity;
whereby when said sealing means is pressurized by fluid from either side thereof upon closing of said closure means, the parallel relationship of the planar surface and the axial centerline causes said back-up means and fluid directed on said inner portion to apply their combined forces substantially perpendicular to the peripheral land to effect sealing of said valve.

2. The bi-directional valve of claim 1, wherein the shoulder ring portions cooperatively engage their respective grooves, thereby acting as stop means to control the amount of projection of said sealing means radially into the passage and prevent blow out of said sealing means.

3. The bi-directional valve of claim 2, wherein each of the pair of shoulder ring portions is of substantially trap-ezoidal configuration.

4. The bi-directional valve of claim 1, wherein said outer portion is secured in a portion of said chamber and is of a volume of mass larger than the volume of material that can be contained in the portion, so that, said outer portion is compressed therein forming a fluid leak-tight seal about its periphery.

5. The bi-directional valve of claim 1, wherein said L-shaped portion is resilient, flexible and substantially of non-conical arcuate configuration, whereby under fluid pressure said L-shaped portion forms a radii-arc shape.

6. The bi-directional valve of claim 2, wherein each of the grooves is of substantially trapezoidal configuration.