CA1233458A - Gate valve - Google Patents

Abstract

GATE VALVE
Abstract of the Disclosure A casing of a gate valve accommodates a seat, a gate having a tapered face made in the gate surface in the direction of its movement in the shut-off direction on the side opposite to the side facing toward the seat. A
stop is provided for engaging the tapered face of the gate, the stop being secured to a rod which is installed trans-versely of the centerline of a passage of the casing.
A sleeve is installed in the casing wall for rotation re-lative to the casing. The inner surface of the sleeve is coaxial with, and surrounds the rod and the longitudinal centerline of the outer surface of the sleeve is eccentri-cal with respect to the longitudinal axis of the rod.

Description

~33~8 he invention relates to shut-s~f pipeline fittings, and more specifically it deals with a gate valveO
A gate valve according to the invention ma be most efficiently used in pipelines intended for conveying sus-pe~ded abrasive materials/ preferably slurries.
The invention may be used in the mining, c~n~truction and chemical industries and also it other industries employ ing bydraulic and pneumatic conveyance ox fluids in the form ox suspensions and slurries containihg solid partic_ les, especially of fluids which cause a highly intensive wear of the seat and gate which should be replace during operation now in the art is a gate valYe, comprising a cawing having a passage. A gate is accommodated in the casing and a seat is installed in alighment with the centerline ox the passage (cf. ~SS~ Inventor's Certificate ~o.45092~, Cl. F 16 k ~f14, F 16 k 3/~0, Nova 25, 1974).
Two stops are installed transversely ox the ce~terli-ye of the passage, the stops eDgaging with their tapered surfaces tapered faces of the gate provided on the gate side opposite to the wide thereof facing toward the seat, when the gate is in the closed position.
he stops ara disposed so that each stop is locatad on the side of the gate opposite to the side therao~ fa-cing toward the teat 3 and adjacent to the side surfaces at the level of the passage centerline.

- 2 ~33~

The tapered surfaces are provided ox the side of the gate opposite to the side t~lereo~ ~aci~g toward the seat and make an acute ankle with the direction of movement of th6 gate into it shut-off position, 'iVhen -the stops engage the tapered surfaces of the gate, they urge the gate cast the end race of the seat racing toward the gate thus ensuring the sealing when the passage it shut-of~.
For tightly pressing the gate against said end race of the seat arid for ensuring the tightl;y sealed shutting -off of the passage, the tops should accurately mate with said tapered surfaces.
It the prior art gate valve the stops are rigidly secured to the end fa¢e of rods accommodat ed in the casing.
Mach rod is installed in a hole of a casing wall along an axis extending transversely of the centerline of the passa-ge for a limited rotation abollt its agis.
As a result of a rather rapid wear of said seat and gate during operation of the gate valve with abrasive slur-ries, the distance from the end face of the seat facing toward thy cooperating surface to the surface of the stops e~gagi~g the tapered faces of the gate should be adjusted jot unfreque~tlY~
In the prior art gate valve the end face portion ox each rod racing toward the passage is made in the form ox a step wormed by cutting~off the cylindrical part ox the rod to one half ox its diameter.

3 --The stop is secured to the slat faces of the step facing toward the seat 9 and a set of thin spacers are ins-talled between this surface of the step and the surface of the stop coin toward this surface.
By varying the number of the spacers and thickness ox said set the diskance from the surface of the seat facing toward the gate to the stop surfaces e~agi~g the tapered races of the gate may be adjustedO
he amount ox rotation of each rod is determined by clearances between the end of a rigidly secured pin protrud-ing Yrom the casing and the wall of a groove made in the rod.
Owing to a limited rotation of the rods about their a~es~ the rods intimately engage said tapered faces ox the gate with their surfaces engageable with the tapered faces of the gate thereby compeDsati~g for ma~ufacturi~g tolera~-ces of angles of taper the the prior art gate valve is ussd~ the abovedescrib-ed adjustment of the distance from the surface of the seat racing toward the gaze to the sur~ace~ of the stops enga-geable with the tapered faces of the gate by varying the umber of spacers and thickness of the set of spacers is di~icult because the rod with the tops secured thereto should be withdrawn from the casing which i3 only possible after the disconnection ox the pipeline thus impairing the cost-ef~ectivenessO
In addition, thin spacers which are normally used in ., Lo _ ~33~

the stops have rather short service live because of cor-rosion 9 specially when the gate valves work with abrasi-ve and aggressive fluids ~ummaxy ox the Invention The invention is based on the pxoblem oY providing a gate valve wherein the stop is installed in such a manner as to enable the adjustment of the distance from the surface of the ssat facing toward the gate to the sur-faces of the stops engageable with the tapered fact of the gate on the operating pipeline without wi.thdrawing the stops from the valve casi~g~
This problem is solved by that in a gate valve, comp-rising a casing in which are accommodated a gate, a seat aligned with the centerline ox a casing passage, and at least one stop e~ageable, when the gate is in the shutoff position, with at least owe tapered race ox the Nate provi~
ded on the gate side opposite to its side facing toward the seat in the direction ox its movement to the shut--off positio~7 the top ~ei~g rigidly secured to a rod ins-talled in the casing along an axis extending transversely ox the centerline of the passage or rotation about this axis 80 as to engage at least a part ox the end race ox the rod facing toward the centerline of the passage, ac-cording to the invention, there is provided a sleeve ins talled in a cawing wall or rotation relative thereto tha inner surface ox the sleeve being coaxial with; and surrounding the stop rod, and the longitudinal centerline ox t'ne outer surface of the sleeve being ecc~n-trical with resQect to the longitudinal axis of the rod.
he installation of the rod to which is secured the stop in the sleeve installed in the casing wall and having the inner surface coaxial with the stop rod and the lon-gitudinal centelline of the outer surface offset with respect to the longitudinal axis ox the rod makes it pos-sible to adiust the distance from the end face of the seat facing toward the gate to the surface ox the stop incli-ned with respect to the gate by rotating the sleeveg De-pending on the direction of rotation of the sleeve, the surface of the stop which is inclined with respect to the gate will either move closer to the end face of the seat facing toward the gate or away therefrom thus varying said distance owing to the eccentricity of the outer surface of the sleeve with respect to the longitudinal axis ox the rodO
'this construction of the gate valve makes it possib le to adjust the distance from the end face of the seat to the surfaces of the stops facing toward the seat on the operating pipeline, without withdrawing the stops and rods from the casino- thus substantially saving labour effort and time.
The gate valYe preferably has a pin rigidly secured to the rod, extending transversely of the longitudinal centerline ox the rod and passing freely through the slee-ve, the end of the pin being freely received in the casing ~23;3~

having or tnat purpose grooves open to~lard the sleeYe for receiving each end of the pin, the side walls of the groove limiting the displacement of the pin ends when the tapered face of the gate en~a~es the stop, and the sleeve has two radially extending through holes having a angular extent equal to a maximum amount of rotation of the sleeve.
he provision ox the abovedescribed pins limits the angle of rotation of the rods within a predetermined range and eliminates an inadvertent rotation ox the stops under the action of the pipeline vibrations or my virtue of other factors toward the seat thereby preventing an cause which might result in a damage to the stops and impro ving the reliability of the gate valve.
Owing to the provision of the radially extending through holes in the sleevo; the pin, which is rigidly ye-cured to the rod, does not prevent the sleeve from being rotated over a angle required or the adjustment.
The eccentricity is preferably such that its ratio to the outside diameter ox the sleeve should not be in excess of one-half of the coefficient of friction between the sleeve and casings This facility prevents the sleeve prom inadvertently rotating under tho action ox external factors and elimina~
ten the undesirable change in the distance from the seat surface facing toward the gate to the surface of the stops engageable with the tapeIed faces of the gate.

~23~

The sleeve preferably has on the end face side op-posite to the side Yacing towald the gate a portion prot IUding outside the casing, said portion being adapted to take-up a force causing rotation ox the sleeve.
he provision of the portion protruding outside the casing facilitates the employment of tools (levers; wren-eke and the like) for Turin the stop it the desired direction in performing the adjustment operations.
Annular members made ox a wear-resista~t material are preferably rigidly secured to the surfaces of the seat and gate engageable with each other when the gate is it the shut-off position This facility prolongs the service live of the seat and gate which is especially important with the abovedescri-bed cons~ructio~ of the gate valve wherein a tight enga-geme~t of the gate and seat is ensured when the gate is in the shut of position which in certain applications might otherwise result in rather strong wear of the gate and seat.
he axis of the a~ular member cured to the seat is preferably offset with respect to the axis of the seat so that the annular member should be offset in the direc-tio~ of movement of the Nate when the gate is moved into its shut-o~f position.
This oilily results in that the working surface ox the teat is disposed outside the zone of action of abrasive particles which are pres0nt in thy, flow so as to prolong the service life ox the gate valve 9L~3~

The gate valve according to the invention enables the adjustment of the distance from the surface ox the seat racing -toward -the Nate to the surfaces of the stops e~a~eable with -the tapered faces ox the gate on the ope-rating pipeline, without withdrawing the stops prom the valve casi~g~
In addition 9 the gate valve according to the inven-tion has comparatively long servico live, it is reliable and convenient in operation.
he invention will now be described in detail with reference to the accompanying drawings illustrating a spe-cific embodime~t~
Brief Description ox the Dxawings Figure 1 schematically shows a gate valve according to the invention7 it a lo~itudinal section;
Figure 2 is a sectional view taken alosg the line II in Figure 1;
Figure 3 is an enlarged detail it P`igure 2;
Figure 4 is an enlarged sectional view taken along the live IV-IV ir. figure 3;
Figure 5 schematically shows a seat, a part of a gate, and a stop; vectors of forces between the gate and stops are also show on the enlarged scale;
igure 6 schematically shows a enlarged view of a seat, a part ox a gate, and a stop in longitudinal section when tapered face ox the gate are made with a deviation of their a~gl.e ox -taper toward the stops;
Figure 7 is ditto, with the gata tapered races made with their angle of' taper in the direction away from the f 1~ CJ

~2 ~3 FiOure 8 schema-tically shows an enlarged view, in longitudinal section, ox a paIt ox a gate and a stop when the gate thickness deviates from a preset thickness; the gate in the shut-o~f position and the respective position ox the stop are shown with dotted lines, Figure 9 schematically shows an enlarged view, in lonOitudinal section, ox a seat and a part of a gate at the beginning ox the gate movement into its open position.
he Preferred Embodiment ox the Invention A gate valve according to the invention comprises a casing 1 (figure 1) having a passage 2 for a fluid contain-ing solid abrasive particles, in particular, a slurry.
he passage 2 extends in the casing 1 along its longi-tudinal centerline 3.
The casing 1 has substantially over its whole h0ight a configuration of` a cylinder with a centerline extend-ing at right angles to the centerline 3. A end plate 5 shaped as a part of a sphere is secured at the top to a Lange (without re~ere~ce) of the casing 1 by means ox a Lange (without reference).
Cylindrical butt pipes 6 integral with the casing 1 are provided in alig~men~ with the centerline of the passage 2 of the casing lu the butt pipes 6 are designed for connection to a pipeli~ (not shown through which a slurry from a source (not shown) is to be co~veyed~

~2 ~3~

Tb~ lower wall Do the casing 1 is of a bent c~nfigu-ration at a point adjacent to the centerline 4 as desert bed it detail belDw.
A ga5e 7 is installed in the casing 1 along the cen--terline 49 and the Nate is opera-tively connected to a dri-ve 8 by means of a rod 9 extending thrDugh a hol0 (without reference) in the end plate 5 along the cent0rline 4 as shown at the top of Figure 1a The drive 8 ma be o-f any appropriate known type, and this drive will not be described in detail herein because it has no bearing on the inventionO
seat 10 is tightly fitted in the casing 1, in a socket (without reference) made for that purpose in a pox-tiDn of the casing protruding inwardly the seat being aligned with the centerline 3. the side of the gate 7 fa-cing toward the seat 10 has an annular projection 11 defin-ing a working surface ox the gate 7, also designated at 11, which is designed for an intimate engagement with an end face 12 of the seat 10 facing toward the gate 7,.
which it hereinaft0r referred to as the working surface 12.
A surface 13 of the gate 7 w~icb i5 opposite to its working surface 11 is flat in the top part of the gate 7 as shown in Figure 1 and extends at right angles to the cen-terline 3 7 and the lower part of thy surface 13 of the gate 7 has an extension .in the form ox a tapered face 14 which makes an acute angle cC with a vertical plane per-pendicular to the centerline 3 it the directiDn Df movement of the gate 7 into its s~ut-off position.
, ~11-~33~

'the cross-sectional area of the upper part ox the gate 7 is ~;reateI than the cross-sectional area of its lower part.
The inner sur~ac~ of the lower part of the casing 1 below the Nate 7 has a cylindlical portion 15 which is spaced from the tree end ox the gate 7 when in the shut--off position.
The cylindrical portion 15 is conjugated with a ta-pering portion 16 which is conjugated v~ith the ten sur-face ox the righthand butt pipe 6 as shown in ~}gure 1.
Owing to the provision ox the tapering portion 16 of the east 1, solid particles present in a fluid conveyed through gate valve and settling below the gate 7 are cau-sed to move by the tapered face ox the free end ox the gate 7 into the righthand butt pipe 6 as shown in Figu~ 1 without hampering the complete shutting-off of the passa-ge 2 of' the casing 1.
The casing 1 has two cylindrical stops 17 engagea~le with thy tapered race ~4 when the gate 7 is in the shut--off position.
he stops 17 are spaced from each other ox the side of the tapered race 14 of the gate 7, adjacent to side pa-ces 18 ox the gate (Figure 2) at the level with khe cen-terline 3 of the passage 2.
ach stop i8 rigidly secured by a known means to a rod 19 which is installed in the casing 1 transversely ox the centerline 3 of the passaKe 2 f'or a limited rota-tion about a axis 20 of the rod 19, together with thy rod 19~

ach stop 1~7 enrages a part of a end face 21 of the rod 19 facing toward the centerline 3/ of the passage ED
A periphery 2Z (Figure I) o.~ the stop 17 is it the form of a half-cyli~der, and the outer suLface of the stop is an extension of the cylindrical surface ox the rod 19.
A part of the surface 22 of the stop 17 facing to-ward the Nate 7 is flat and is inclined alto at an acute angle O with respect to a vertical plane perpendicular to the centerline 3 of the passage 2 (Figure l Sleeves 23 (Figures 2 and 3) are provided in thy ca-sing 1, each sleeve surrounding a respective rod 19. Mach sleeve 23 is installed in a respective through hole (wi thout reverence) of the wall of.the casing 1 for rotation relative to the casing 1.
The inner surface 2~ (Figure 3~ 4) of the sleeve 23 is coaxial with9 and surrounds the rod 19.
he outer surface 25 of the sleeve 2~ Yates with the surfaces of the through hole in the wall ox the casing 1.
The mating surfaces 24 and 25 of the sleeve 23 are sealed with respect to corresponding mating surfaces of the rod 19 and casing 1 by means ox seals 26 and 27 which may be of any appropriate known ape (figure 3).
The lo~gitudi~al centerline ox the outer surface 25 ox the sleeve 239 the projection of which on the plane of the drawing it Figure 4 it designated as a point 28, i3 offset with a eccentricity f with respect to the axis 20 ox the rod 19 (Fi~ura 3) which is shown as the point ?0 in Figure 4, ~33~

his construction makes it possib:Le to adjust the distance "B'l (Figures 1 and 3) from the end face 12 of the seat 10 facing towa:rd the gate 7 to the flat surface ox the stop 17 by rotating the sleeve ~3 about its longi-tudinal centerline shown as the point 28 in figure 4.
This facility enables the adjustment of the distance "Bll upon replacement of the seat 10 and gate 7 without removing the casing 1 from the pipeline, and any fitting operation during installation of a new set of the seat 10 and gate 7 may be dispensed with.
pi 29 (Figures 3 and 4) is provided which is ri-gidly secured to the rod 19 and extends at right angle to the axis 20 ox the rod 19.
he pin 29 passes freely through the sleeve 23 and has its ends freely received in the casing 1. For that purpose grooves ~0 open toward the sleeve 2~ are made in the casing for each end ox the pin 29.
Side walls 31 (Figure 4) of the groove ~0 of the ca-sing 1 are designed for limiti~ the displacemert when the tapered ace 14 of the gate 7 engages the stop 17, The sleeve 23 has two radially e~te~ding through holes 3~ respectively, fvr a tree passe therethrough of the ends of the pin 29.
The annular extents ox the holes 32 are equal to maximum angles ox rotation of the sleeve 23.
The pins 29 retain the stops 17 rigidly secured to the rods 19 at an angle which is equal to the angle of ~23~

taper ox the tapered face 14 of the gate I, and the tree ar.rangement of -the ends ox the pins 29 in the groove 30 ox the casing 1 allows to the sur~ace.s of the stops 17 to align against the tapered face 14 of the gate 7 thus compensating or a ~lanufacturing tole:ra~ce of the angle a ox taper of the tapered race 14 which is imposed it ma-king the gate 7.
Ow-ing to the provision of the radially extending through holes 32, the yin 29 does not prevent the sleeve 2~ prom rotating when the adjustment operation is perfor-Ed he eccentricity " " is such that the ratio ox the eccentricity to the outside diameter of the sleeve 23 "I"
is not in excess of one-half of the coefficient ox Eric-tio~ 'I " between the sleeve 23 and the casing 10 In this case as show in Figure I, the force "C"
of pressure OI the tapered face 14 of the gate 7 applied at a point 33 at which the centerline intersects the tapered race 14~ is spaced from the point 28, which is the pro jection ox the longitudinal centerline ox the outer surface ox the sleeve 23 on the drawing plane, at a distant ce equal to the eccentricity l statical equilibrium of forces O " and "C " equal to the force "C" and directed oppositely to owe another occurs at the point 28, the couple of forces "CC " results it a mo~en-t Of thigh tends to turn the sleeve 23 coun-terclo~kwise so as to increase the distance "B" thus ten-dip; to unseal the gate valve.
~15 3~

At the same time, the force "C tll thigh is equal to the force "C1', urges the outer suIface 25 of the sleeve 23 against the wall 34 (Figure 5) of -the hole in the ca-sing 1 provided for thy sleeve 23 thereby creating a fric-tion force "F" which is equal to a pxoduct ox the force "C" = C by the coefficient of friction "I' between the sleeve 23 and the wall of the casi.ng 1.
he friction force "F" acts with an arm equal to one-Hal of the diameter "I" of the outer ~ur~ace 25 of the sleeve 2~. As a result ox the action of the force "C" a moment "M"' of friction (not show) is applied which is equal to a product of the friction force "I" by o~e~half of the diameter "D". In order to prevent -the sleeve prom inadvertently rotating about its longitudinal centerline, it is necessary that the inequality I'>, M be complied with, i.e. Do With the ratio of the eccentricity "I" to the diame-ter "D" ox the sleeve 2~ smaller than one-hal~ ox the coef ficient of friction " the sleeve 23 is retained its inadvertent rotation is prevented, and tne conditions for sealing of the gate valve are ~mproved~
On the end race side opposite to the side thereof racing toward the gate 7, the sleeve 2~ is held against axial movement by a rotating ring j5 (Figure 3) which is installed in a annular groove (without reference) ox the casing l and the sleeve 2~ has a pOItiO~ 36 protruding outside the casing 1 for taking-up of a foxce applied or rotation of the sleeve 23.

3L2~

The protruding portion 36 ha a cylinarical periphery (wi.thout reference). A hole 37 is made in the protruding portion ~6 to extend thxough the lon~itudi~al centerline of the outer suu~ace 25 of the sleeve 23, at right angles thereto.
'the hole 37 is designed or receiving a lever (not shown) to which is applied a force fox lotating the sleeve.
This facilitates rotation ox the sleeve 23 in making the adjustment.
To prevent the gate 7 and seat 10 prom being worn upon a intimate engagement of their surfaces under the action ox the stops 17~ annular members 38 and 11 (Fi-gure 1) are rigidly secured to the surfaces of the seat 10 and gate 7 engaging each other when the gate 7 is in the shut-off position, the annular members being made of a wear-resistant material and de~i~i~g projections ox the set 10 and gate 7, having working surfaces 12 and 39, respectively Owing to the provision ox the annular members 38 and 11 made of a wear-resistant material the service life of the data 7 and seat 1Q engaging each other is prolonged.
The annular member 38 is rigidly secured to the sur race of the seat 10 in a offset position, with an o~'~se~
in the direction ox movement of the gate 7 when the gate i8 moved into the shut-o~f position Jo that a crescent--shape recess 40 is defined adjacent to the working sur-face 12 ox the seat 'lO (figure 9), which is formed by arcs ~2 3~
of circlas of the cross-secti~ of toe passaOe 2 and the inner surface of th0 annular member 38~ This construction of toe seat 10 allows the lower part of the working surface 12 of the seat 10 to be dlspDsed outside the zone of the mainstream of the fluid flDw, which migbt otherwise be subjected to the action vl coarsest and most abrasive sDlid particle presen-t in the flow which are fDrced under gravity to the lower boundary of the flow. the service live of the working surfacss ox the sea 10 and gate 7 is thereby further prolonged The gate valve according to the invention functions in the following mannerO
Under tbe action of the drive 8 thy rod 9, connected to the drive, tarts reciprocating along the centerline 4 of the casing 1 and causes the movement of the gate 7 connected to the rod 9.
When the gate 7 moves upward in Figure 1, the working surface 39 of the annular projection 11 cf the gate 7 dis-engages from the working surfaee 12 of the seat 10 and opens ths passage 2 Df the casing 1 for the passage the-re~hrough of a fluid being conveyed.
When the gate 7 moves downward in figure 1, the wor-king surface 39 of the annular projection 11 Df the gate 7 engages the working surface 12 Df the seat 10 and shuts--of the passage 2 of the casing 1.
The tapered face 14 of the gate 7 m~ki~g an acute angle " a 1I witb a vertical plane perpendicular to the cen-3~

terline 3 of the passage 2 engages the slat surfaces 22 of the stops 17 which are also inclined at an acute angle at to a vertical plane perpendicular to the centerline 3 of the passage 2. When the tapered f'ace 14 engages the fat surfaces 22 of the stops 17, the working surface 39 of the annular projection 11 of the gate 7 is urged against the working surface 12 ox the seat 10 thus ensuring the sealed shutti~g-o~ of the passage 2.
Solid particles of the fluid being conveyed thus get beneath the free end of the gate 7 and are caused to move under the action of the free end of the tapered face 14 ox the gate 7 along the tapering portion 16 ox the casing 1 into the righthand butt pipe 6 in Figure 1, without hamper-ing the movemeut of the gate 7.
In case ox deviations ox the angles of taper a of the gate 7 and stops 'l7 as a result of manufacturing to-lerances in making the gate valve, e.g. by an angle (figure 6) the gate 7 moving downward, short ox its lower-most position, engages with its tapered race 14 with the slat surface 22 ox the 5~0p 17 facing toward the gate 7 only along the lower line shown by a point 41 in Figure 6, rather thaw o'er the whole surface. the positions of the lower end ox the tapered face 14 ox the gate 7 and the surface 22 of the stop 'l7 at the moment ox engagement along toe live corresponding to the point 41 are shown with dotted lines it Figure 6, During further downward movement of the gate 7 its tapered face 14 urges the end ox the slat surface 22 ox ~3~

the stop 17 to the I`i ' ht in Figure 6 and causes its ro-tation countelclockwise about the axis 20 ox the rod 19 50 that when -the gate 7 is in the lowermost position the flat surface 22 is in colnplete engagenent with -the tape-red f'ace 14 of the gate 7 as shown with solid lines it Figure 6 he pin 29 a].so rotates counterclockwise through a angle " I" from the position shown with dotted line to a position shown with solid line. As one-half of the angular exten-t ox each groove 30 of the casing 1 is equal to an angle "I ", which is greater than the angle "I " equal to one~half of tha manufact~ing tolerance for the gate 7, the groove 30 hampers rotation of the stop 17 over the angle " ".
As the angular extent 'I " of the radially extending through holes 32 ox the sleeve 23 is much greater thaw the angle "cC", the sleeve 23 also does not hamper rotation ox the stop 17 rigidly secured to the rod 19 about the axis 20 of the rod 19.
Therefore the slat surface 22 ox each stop 17 is po-sitioned9 and i~imately engage the tapexed face 14 of the gate 7, Jo as to tightly urge the working surface 39 ox the annular pro jectio~ 11 of the gate 7 against the working surface l of the seat 100 It the angle ox taper a ox the tapered race 14 of the gate 7 deviates in the direction opposite to thaw shown in Figure 6, as shown with dotted line9 the tapered ~33~8 face 14 engages the flat surface 22 ox each stop 17 alongthe line show my a point 42 it Figure 7 and causes its rotation clockwise with the result that in the lower-most position of the slat surface 22 this surface intima-tely. ongages the tapered face 14 ox the gate 7 so as to tightly urge the working surface ~9 ox the annular pro-jection 11 of the gate 7 against the working surfaca 12 of the seat 10~
Thus a tight sealing in shutting-o~ the flow ox a fluid being conveyed is ensured.
The self-alignrnent ox the flat surface 2~ ox each stop 17 improves the cost-effectiveness of the gate valve owing to a lower labour effort for the manufacture ox the gate 7 since a rather labour-co~suming manufacturing pro-cess associated with the fitting ox the angle ox taper 1l~ 17 of the tapered ~ac~ 14 of the gate 7 to the angle of incli-nation of the flat surface 22 of each stop 17 may be dis-pensed with.
Deviations ox the distance "B" prom the surface 12 of the seat 10 to the flat surface 22 of the stop 17 may occur during manu~acture~ the distance "B" is equal to the dime sion~ ox the gate 7, namely to its thickness as shown it Figure 1 along the centerline 3 when the gate 7 is in the shut-o~f position The dimensiQns ox the gate 7 may be equal to "B1"
(Figure 8) which is greater than the distance "B", or "B2" (jot shown) which it smaller than the distante "B"~

~23~5~3 If the dimenslon "B1" of the gate 7 is treater than thedistance "B", the gate 7, will stop short ox its lowermost position, and in this case the working suI~ace 39 of the annular projection 11 ox the gate 7 will not engage the working surface 12 of the seat 10 so that the slow will not be shut-of~ with a desired tightness.
r~his may be remedied by rotating the sleeve 23 in the direction shown by arrow "G". the point 33, which is the center of the cross-section ox the stop 17 transversely of the axis 20, rotates counterclock.~ise about the point 28 along a circle of a radius "R" as shown with a dash--a~d-dot line in figure 8. The stop 17 will thus move along the centerline 3 ox the passage 2 as shown by arrow "H" so as to enlarge the distance "B7'~ 'the sleeve 23 is rotated until the distance "B" becomes equal to t'B1" and the stop 17 is in the position shown with dotted line in Figure 8.
fter this adiustment the gate 7 will be in the posi-tion show with dotted line in Figure 8 wnen in thy shut-of~ position thereby providing for a tight shutting--of of the passage 2.
he the dimension "B2'i of the thickness of the gate 7 is smaller thaw the distance "B", the sleeve 23 is rotated cl.ockwise in the direction opposite to that shown by arrow c The stop 7 will then move along the center1i~e 3 of the passage 2 to the left in figure 8 so as to reduce the dimensions "B" to the value of "B2"- This provides I% 33 for a tight shuttingr-off of the passage 2 when the gate 7 it in the shut~o~f position.
Owing to the adjustment of the distance "B" by meats of the rotatable sleevl~ 23 a rather labour-consum-ing operation of ~ittin~ the thickness of each gate 7 to a distance "B'l from each stop 17 to the working surface 12 of the seat 10 ma be dispensed with ith a minor opening ox the passage 2 between the seat 10 and gate 7 at the beginning of the opening opera-tion or at thy end ox the shutting-off the flow of fluid passing through such clearance 4~ (~'igure 9) in the passa-ge 2 as shown by arrow "J" has increased velocities owing to the restriction. In view of higher velocities the wear of' the working surfase 12 ox the seat 10 and working sur-face ~9 of the gate 10 may be accelerated. This may cause a premature failure of the abovementioned working surfaces and shorter service life ox the ~alveO
The service life of the working surfaces 12 and 39 in the gate valve according to the invention is prolonged because these surfaces are defined on annular members 11 and 38 made ox a ~ear-resistant material and rigldly secu-red to the gate 7 and seat 10. The offset position of the annular member 38 of the seat 10 in the direction ox move-met of the gate 7 when it is moved into the shut-off po sition also contributes to the prolongation of the service life. Owing to this facility 9 the woIking surface 12 of the seat 10 is arranged outside the zone ox action ox the mainstream abrasive flow directed along arrow 11JIl, andthis abrasive action is ta~en-up by the end face 44 of the crescent shaped recess 40 of the working surface 12 ox the seat 10 that doe not participate in -the sealing of the passage 2.
Thus the woIking surfaces 12~ ~9 of the seat 10 and gate 7~ respacti~ely, are protected against the wear by the abrasive flow, and their service live is prolonged The use of the invention improves the cost-ef~ective-ness of the gate valve in the manufacture owing to the elimination of rather labour-consuming fitting operations, makes it possible to ensure a desired tightness of sealing in using the production equipment ox lower accuracy.
In addition9 the assembly of rapidly wearing parts of the gate and seat Jay be performed directly on the pipeline without their fitting to the casing (when these parts are replaced during operation) thus lowering the operation cost.
he service live ox the gate valve is also prolonged.
The Nate valves manufactured in accordance with the inve~ion feature an improved cost-effectivene~s in the manufacture, convenience in maintenance and repair and prolonged service life in operation in hydraulic conveyan-ce of bulk abrasive materials in the coal and mining indus-tries and in other industries.

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Claims (12)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A gate valve, comprising: a casing; a passage de-fined in said casing; a seat installed in said casing along the centerline of said passage; a gate accommodated in said casing and designed for shutting-off said passage when engaging said seat; a drive for imparting reciproca-tions to said gate; at least one tapered face in the sur-face of said gate in the direction of its movement to the shut-off position, on the side thereof opposite to its side facing toward said seat; at least one stop in said casing designed for engagement with said at least one tapered face when the gate is in the shut-off position; a rod ri-gidly secured to said stop and installed in said casing along an axis extending transversely of the centerline of said passage for rotation about this axis; said stop engaging at least a part of an end face of said rod facing toward the centerline of said passage; a sleeve installed in a wall of said casing for totation relative thereto;
said sleeve having an inner surface coaxial with, and surrounding said rod, and an outer surface, the longitudi-nal centerline of said outer surface being eccentrical with respect to the longitudinal axis of said rod.

2. A gate valve according to claim 1, wherein there is provided a pin rigidly secured to said rod, extending transversely of the longitudinal axis of said rod, passing freely through said sleeve and having its ends received freely in said casing which has for that purpose grooves open toward said sleeve for each end of the pin, the side walls of the grooves limiting the displacement of the ends of the pin when said tapered face engages said stop, and said sleeve having two radially extending through holes, the angular extents of the holes being equal to maximum angles of rotation of said sleeve.

3. A gate valve according to claim 1, wherein the eccentricity of the outer surface of the sleeve is such that the ratio of the eccentricity to the diameter of the outer surface of said sleeve is not in excess of one-half of the coefficient of friction between said sleeve and said casing.

4. A gate valve according to claim 1, wherein said sleeve has on the end face side opposite to the side fa-cing toward said gate a portion protruding outside said casing which is adapted to take-up a force causing rotation of said sleeve.

5. A gate valve according to claim 1, wherein annular members made of a wear-resistant material are rigidly se-cured to the surfaces of said seat and gate engaging each other when the gate is in the shut-off position.

6. A gate valve according to claim 5, wherein the axis of the annular member secured to said seat is offset with respect to the centerline of said seat so that the annular member is offset in the direction of movement of said gate when it is moved in the shut-off direction.

7. A gate valve comprising: a casing; a passageway defined in said casing having a centerline; a valve seat mounted in said casing substantially coaxially with the centerline of said passageway; a gate mounted in said casing for reciprocating movement into and out of cooperating engagement with said valve seat to close and open said passageway, respectively; drive means operatively connected to said gate to impart said reciprocating movement to said gate; at least one tapered face in the surface of said gate on the side thereof opposite that facing said valve seat and tapering in the direction of said reciprocating movement toward the closing position; at least one stop member mounted in said casing having a flat surface facing and engageable with said at least one tapered surface when said gate is in the closed position; at least one sleeve member rotatably mounted in a wall of said casing for relative rotation with respect thereto, said sleeve member having an inner surface with a longitudinal center-line extending transversely through the centerline of said pas-sageway and an outer surface having a centerline extending eccen-trically with respect to the centerline of the inner surface; a rod member rotatably mounted in said inner surface for rotation about an axis extending coaxially with said centerline of said inner surface and having an end face facing toward the centerline of said passageway, said stop being rigidly secured to at least a part of said end face; said flat surface of said stop lying in a plane including the axis of rotation of said rod member; means to allow limited rotation of said rod member about its axis of rota-tion; means to selectively rotate said sleeve member to adjust the distance between said flat surface on said valve seat; and means to fix the position of said sleeve member against sponta-neous rotation thereof.

8. A gate valve as claimed in claim 7 wherein said means to allow limited rotation of said rod member comprises: a pin rigidly secured to said rod member and extending radially oppositely therefrom transversely to the axis of rotation thereof; two radially extending openings through said sleeve mem-ber through which opposite portions of said pin freely extend, said opening extending angularly an amount equal to the desired maximum angle of rotation of said sleeve; and grooves in said casing open toward said sleeve member positioned to freely receive the ends of said pin and having side walls limiting the displacement of said ends when said tapered face of said gate engages said at least one stop member.

9. A gate valve according to claim 1 wherein the eccentricity of the outer surface of the sleeve is such that the ratio of said eccentricity to the diameter of the outer surface of said sleeve does not exceed one-half of the coefficient of friction between said sleeve member and said casing.

10. A gate valve according to claim 7 wherein said sleeve member has an end face side opposite to the side facing toward said gate with a portion protruding outside said casing which is adapted to facilitate the application of a force causing rotation of said sleeve.

11. A gate valve according to claim 7 wherein annular members made of a wear-resistant material are rigidly secured to the surfaces of said valve seat and gate engaging each other when the gate is in the closed position.

12. A gate valve according to claim 11 wherein the axis of the annular member secured to said valve seat is offset with respect to the centerline of said valve seat in the direction movement of said gate when it is moved in the closing direction.