IL45581A

IL45581A - Ball valve

Info

Publication number: IL45581A
Application number: IL45581A
Authority: IL
Original assignee: Celanese Corp
Priority date: 1973-09-04
Filing date: 1974-09-02
Publication date: 1977-04-29
Also published as: FI58010C; FR2242619B1; NL161562C; CH592832A5; IN142649B; IE39994B1; SE7411140L; CA1020146A; AR202573A1; NO742726L; FR2242619A1; NL7410544A; ATA629174A; NO136162B; HK31877A; DE2436348A1; NO136162C; GB1456567A; IL45581A0; FI58010B

Abstract

1456567 Valves CELANESE CORP 26 July 1974 [4 Sept 1973] 33171/74 Heading F2V The seating 7 upstream and downstream of a valve member 9 in a ball valve is formed integral with the plastics casing and provided with lips 6, which extend without stress over a plane surface 15 on the member 9 when it is in the open position (as shown in Fig. 6) and which are flexed to effect a line closure at 26 when the member is in the closed position (as shown in Fig. 7). The plastics material is selected from the polyolefins, epoxies, acrylonitrile-butadiene-styrene nylons, acrylics, polyacetals, polyvinyl plastics and polystyrenes. The easing is moulded in situ around the closure member. [GB1456567A]

Description

•ΊΠ3 ointm BALL VALVE BACKCROU-ID OF TH5 DISCLOSURE Field of the Invention This invention is directed to a ball valve. More specifically, this invention is directed to a ball valve having a unitary body seal member integrally connected to the housing. Still more specifically, the instant invention is directed to a ball valve having a plastic housing provided with an integral homogeneous body seal member, which provides a seal for the rotary plug disposed in. the housing.

Background of the Prior Art Ball valves have received wide acceptance in all types of liquid flow control applications. Their wide use is due in no small part to the ease and quickness of opening and closing these valves. Moreover, because ball valves are often constructed of plastic materials, they afford protection against many corrosive fluids, and thus can be used in many process applications.

A major disadvantage, however, to the ball valves of the prior art is that the ball valves of the prior art employed separate sealing rings within the ball valve housing. The use of separate sealing rings, in addition to adding* to the cost and complexity of the valve, can result in leakage through the valve due to the wearing out of these sealing elements. Thus, with separate plug sealing members, leakage can develop through two paths; between the ro-tary plug Another disadvantage of the ball valves provided with separate plug sealing rings in a valve housing is the possibility that the rings can become dislodgedby flow or by rotation of the plug.

Sealing members or seats, as employed in the internal housing of ball valves of the prior art resist leakage and/or maintain the position of the ball by overcoming the pressure of the fluid stream by compression. The two materials most commonly employed as sealing members are elastomerics and fluorinated hydrocarbons, i.e., Teflon. Although both of these classes of materials resist compressive forces they both are subject to failure in this service. Fluorinated hydrocarbon resins tend to distort by cold flow under prolonged compressive force. Similarly, elastomeric materials under similar conditions take on a permanent set. Distorted fluorinated hydrocarbon seals and permanently set elastomeric seals both tend to leak.

A leaky ball valve must either be repaired by replacing the sealing elements or must be totally replaced. It should be noted in the many designs, it is not feasible to replace the sealing members, thus necessitating the replacement of the valve. In either case, flow in the line controlled by the valve must be shutdown which, depending upon the service, may be quite costly. , The problems associated with the use of sealing elements in ball valves is considered in U.S.. Patent 3, 271, 8 5. However, manufac uring 'sa ball valve which overcomes the problems of disposing sealing members in the valve. In that invention this problem was overcome but the sealing elements were retained in the final fabricated valve. Thus, the valve of that invention is similar to the other valves of the prior art in that sealing elements are retained in the internal housing of the ball valve.

SUMMARY OF ΤΗΞ INVENTION It has now been found that a ball valve may be fabricated which eliminates the need for separate sealing members while providing improved sealing properties. Thus, the problems associated with elastomeric seals, the taking on of a permanent set, and fluoro-hydrocarbon seals, the distortion of the seal under compression, are eliminated. This is all accomplished by introducing a stronger more lasting sea ΛΙ€chanism which is more easily fabricated at lower cost. This is all accomplished by the employment of a homogeneous valve body, seat, and flexural seal. The unitary design provides greater resistance to leakage while providing longer lasting properties. The wear properties are increased because of the unique design of the flexural seal which is subject to lower stress forces than is a compression seal. Thus, less distortion due to cold flow occurs.

In accordance with the instant invention a valve is provided which includes a housing provided with inlet and outlet means. A rotatable rotary plug, said plug provided with a circular orifice, is disposed within the housing between the inlet and outlet means. The rotatable rotary plug is provided with a seal by means of a homogeneous body seal member integrally connected to the inside of the housing.

BRIEF DESCRIPTION OF THE DRAWINGS The instant invention can be better understood with reference to the accompanying drawings which: Figure 1 is an elevational view of a preferred embodiment of the ball valve of this invention; Figure 2 is a cross-sectional view taken along line 2-2 of Figure 1 with the ball valve plug in the open position; Figure 3 is a cross-sectional view taken along line 3-3 of Figure 1 with the ball valve plug in the closed position; Figure 4 is a transverse sectional' view taken along line 4-4 of Figure 1 showing valve in the closed position; Figure 5 is a cross-sectional view of the plug taken along line 5-5 of Figure 3; Figure 6 is a fragmentary end view of a portion of Figure 2 indicating the sealing relationship between the plug and the housing seal with the plug in the opened position; Figure 7 is a fragmentary end view of a portion of Figure 3 indicating the sealing relationship between the plug and the housing with the plug in the closed position; and Figure^ 8 is an exploded view of the elements forming DETAILED D>∞-RIFTIO Turning now to the drawings in detail , a preferred embodiment of the ball valve of this invention is generally indicated at 1. The valve 1 includes a housing member generally indicated at 2. The housing includes a pair of cylindrical sections 3 and 5 which provide inlet and outlet means to the conduits (not shown) with which valve 1 communicates. It should be appreciated that although section 3 and 5 are preferably a unitary part of the housing 2, they may alternately be separate sections attached .to the housing, such as by threaded nuts or the like. As those skilled in the art are aware, the cylindrical sections 3 and 5 may be threaded (not shown) , either internally or externally, to connect with the communicating conduits. Alternately, the cylindrical sections 3 and 5 may be welded, flanged or otherwise connected to the communicating conduits.

The housing 2 also includes a unitary body seal member 7 situated intermediate between the cylindrical sections 3 and 5. The body seal member 7 includes a lip seal 6 which will be discussed in greater detail hereinafter.

Disposed within the housing is a rotatable rotary plug, generally indicated 9. The plug 9 has a circular orifice 11 to communicate between cylindrical sections 3 and 5 when the plug is in the open position. A stem 13 is provided to connect the plug 9 mt& a handle, described below ^ -In the preferred integrally connected and the unitary plug-stem of the preferred embodiment illustrated in the drawings is designated generally at 10.

A unique feature of the plug 9 resides in the non-circular shape of that portion of the surface of the plug 9 designated by reference numeral 15. It is emphasized that but for the surface 15, the remaining surface of the plug 9 is spherical about the axis of rotation 16. However, the surface 15 of plug 9, which is situated adjacent to the inner diameter 12 of the circular orifice 11, is substantially flat and parallel to the axis of rotation 16. The surface 15 is defined by the inner diameter 12 and a second, outer circle or circumference 14. The surface is thus substantially flat, although the surface 15 is shown in the drawings to be completely flat. The outer circumference 14 of surface 15 may be slightly carved, if desired, to ease rotation of the plug 9.

The plug 9 is accommodated in the body seal member portion 7 of the housing 2. In a preferred embodiment this is accomplished by predisposing the unitary stem-ball member 10 in a mold into which a molten plastic is injected. The mold is so designed to form a housing depicted in the drawings at 2. Obviously, this production method results in an excellent fit for the plug-stem member 10 within the housing 2.

The plug-stem member 10 is turned by a handle 20 which transmits a turning force imparted by an operator. The stem is connected to the handle by means of a key 17 which extends from the stem 13. The key 17 is accommodated in an appropriately shaped cutout portion (not shown) located in the bottom surface of the handle 20. The handle 20 is also provided with a curved guideway opening 22. An extensio 24 of the housing 2 fits into the guideway 22 to prevent the handle 20 from turning through an angle of more than 90°.

Although the ball valve 1 may. be constructed of any v. suitable material, it is preferable that the material of construction be a plastic or plastics. This is especially true of the housing 2. An injectable plastic provides an excellent method for fabricating the housing 2 as well as pro- viding advantages in terms of the types of fluids that may be controlled by this valve. The plastics contemplated for employment as the materials of construction of the housing 2 all withstand acids, bases and other chemicals that may be employed in process applications. Even the use of water, the most commonly employed liquid, is best accommodated in a plastic housing in that plastics provide excellent- corrosion resistance for water. Preferably the plastic employed as the housing 2 of the valve 1 is selected from the group consisting of polyolefins, epoxi acrylonitrile-butadiene-styrene, nylon's, acrylics, polyacetals, polyvinyl plastics and polystyrenes. Of these, a particularly preferred plastic for the housing 2 is polyvinyl chloride.

As previously mentioned, a preferable method for fabricating the valve is by injection of molten plastic into a mold which results i the formation of -the housin subse u nt to the disposition of the plug 9 in the mold. In a preferred embodiment the plug 9 is also constructed of a plastic material. In the preferred embodiment wherein a plastic plug 9 is employed, it is preferable that the ball be constructed of a polyacetal. In one preferred embodiment the polyacetal employed is Celcon, which is a trademark for a polyoxymethylene copolymer. As those skilled in the art are aware, Celco is a copolymer of oxymethylene and ethylene. Another preferred material of construction of the plug 9 is chlorinated polyvinyl chloride.

It should be appreciated that although plastic is the preferred material of construction for the plug member 9 a metallic construction may also be employed with the proviso that the material be corrosion resistant. It should be further noted that although the stem 13 is integral with the plug 9 in the preferred embodiment illustrated in. the drawings, i.e., member 10, it is also possible that the. stem 13 merely be connected to the plug as for instance by means of a threaded end of the stem connected to a tapped hole in the top of the plug 9. It should be noted that if a two piece plug-stem is employed, it is preferred that the stem be constructed of the same plastic material as the plug.

In operation, the ball valve 1 is opened by rotation, about axis 16, of the handle 20 which transmits a rotational movement through the stem 13 to turn e plug 9 to the Open s ti r 2 Rotation of the plug 9 through an angle of 90° results in the complete closing of the valve. The position of the plug 9 in the closed position is illustrated in Figure 3. Another view of the ball valve 1 in the closed position is shown in Figure 4. This view illustrates the orifice 11 of the plug d disposed normal to the direction of flow.

In conjunction with the opening and closing of the valve a critical feature is the means by which the valve, which is provided with no separate sealing member within the housing 2, is sealed. Attention is directed to the surface 15 of the plug 9 and the lip seal 6, which is a portion of the body seal member 7. As shown in Figure 2 and particularly in Figure 6 the lip seal 6 extends radially inward beyond the outer circumference 14 of the surface 15. In the drawing the lip seal member 6 extends between the inner diameter 12 and the outer circumference 14 of the plug surface 15. It should be emphasized that it is important that the lip seal 6 extend inwardly beyond the outer circumference 14. The distance the lip seal 6 extends beyond the outer circumference 14 is a function of the amount of flexing required by the lip seal 6 to provide a leak-free seal . Thus , the lip seal 6 may extend all the way to the inner dianfier 12 of the plug, if necessary.

The theoretical basis for the requirement that lip seal member 6 extend beyond the outer circumference 14 of the plug is postulated to be due to the requirement that the lip seal 6 be flexed outward to set up a force between the lip seal 6 and the plug 9. It is this force that is postulated to prevent leakage. This force resists the pressure exerted by the fluid stream.

This theory, is lllua r- ed in Figure 7. The force imposed on the lip seal causes the flexible lip seal 6 to bulge outward so thnt the only contact between the plug 9 and the lip seal 6 is at a single point, indicated in Figure 7 as 26. In order to better define this contact, the point of contact 26, is also indicated in Figure 6. Figure 6, like Figure 7, is a fragmentary view, however, Figure 6 shows the plug 6 in the open position whereas Figure 7 depicts the closed] . valve .in the r©j*&»-position.

The above discussion emphasizes that the seal produced by the ball valve 1 is the product of the flexural properties of the lip seal 6. Moreover, the greatest resistance to leakage is, under most pressure conditions, provided by the downstream end of the plug. The upstream end of the plug is in contact with the fluid in the conduit which pushes the downstream end of the plug tightly against the lip seal 6 providing the primary seal against leakage. On the other hand, when the valve is employed in a stream whose pressure is below atmospheric, i.e., vacuum service, the flexural force of the lip seal 6 against the upstream side of the plug 6 provides the primary seal against leakage.

It should be noted that the absence of the surface 15 r-esults in a situation analagous to the lip seal 6 extending circumf rence only to the outer Jjraiualej? 14 of surface 15 of the plug 9 in the drawings. In that case, as well as in the case where there is no surface 15 extending inside of the circular plug is rotated to the closed position. Thus, there is no force exerted by the lip against the plug, resulting in poor sealing, particularly at low pressures.

There is one exception to the lip seal 6 to extend beyond the outer diamefeeg 14 of the surface 15 or alternatively, not to have any surface 15 at all. That is the case where the plug 9 represents a perfect sphere.

In that case there is little possibility that a leakage path would develop. Obviously, such a situation is highly improbable and the need for the surface 15 in conjunction with the lip seal is evident.

The above description which relates to the sealing means for the valve in the closed position obviously does riot apply when the valve is in the open position. When the valve is in the open position the lip seal 6 is not flexed outwardly and there is no force pressing on the plug by the lip seal 6. Thus, when the valve is in the open position there is no stress on the lip seal. Because of this the lip eal cannot distort by cold flow when the valve is in the open position (cold flow does not occur without stress) . Thus, the life of the lip seals are increased even further.

Because there is no force pressing on the plug by the lip seal in the open position, it may be possible for a miniscule percent of the flow to leak between the lip seal 6 of the body seal member 7 and the plug-*stem member 10. In order to · O-ring 19» is provided around the stem 13 to prevent such a leak* It should he emphasized that this O-ring 19 is exposed to far less compressive force and frict-ional wear than a sealing mem er would he if disposed within the internal portion of the houslngo Thus.

It does not as easily fail as would separate sealing, members disposed in the stream, which would he exposed to the full pressure of the awi stream* Moreover, a sealing member such as O-ring 19» disposed on the stem, is easily replaced by the mere removal of the handle and the replacement of the O-ring. It Is emphasized that the use of O-ring 19 is old in the art and represents no part of this Invention.

The pre erred embodiments given above illustrate the scope and spirit of the Instant Invention* Other embodiments within the soope and spirit of this invention are within the contemplation of this invention* Therefore* the scope of tills Invention should he limited only by the appended claims*

Claims

1. 45581/2 Claims : 1. A valve comprising % a unitary housing of moldable nonjmetallic material provided with inlet and outlet channels having peripheries and including end sections formed as homogeneous parts of said housing for connection to communicating conduits on opposite sides of said valve; A a plug mounted for rotary movement at a position between // said inlet and outlet channels and having a through passageway including an orifice with a periphery smaller than the periphery of the adjoining channel; a body seal portion formed as a homogeneous part of said housing and being in sealing engagement with portions of the plug remote from said orifice; and Q an annular lip seal member formed as a homogeneous part of said body seal portion and surrounding said plug orifice, said lip seal member extending radially inwardly from the periphery of said adjoining channel to a position adjacent the periphery of said orifice and being sufficiently thin in the direction of fluid flow through the valve to form a fluid tight seal by causing the radially innermost portion of the lip seal member to flexingly engage an outer surface portion of the plug.

2. The valve as defined in claim 1 wherein the plug contains a recessed annular surface area surrounding said orifice, and wherein the radially innermost portion of said lip seal member extends inwardly to and contacts said recessed area when the valve plug is in the valve open position and flexes over the outer surface of the plug when the valve plug is in the valve closed position. 45581/2

3. The valve as defined In claim 2 wherein the plug is a ball having a substantially spherical shape and the recessed area of the ball is a flattened surface adjacent the orifice, said flat surface extending between the periphery of said orifice and an outer circle.

4. The valve as defined in claim 3 wherein the lip seal member extends radially inwardly from said adjoining channel by a distance between about 1/1Oth and l/8th inch and has a seat thickness of between about 0.03 and 0.05 inch.

5. The valve as defined in claim 4 wherein the innermost portion of the lip seal member extends radially inwardly beyond said outer circle and engages said flattened surface when the valve ball is in the valve open position.

6. The valve as defined in claim 4 wherein the recessed area of the ball is a smooth curved surface free of sharp edges, and the innermost portion of the lip seal member extends radially inwardly to include an annular ridge which faces the recessed area when the valve ball is in a valve open position and which flexes over the ball surface when the valve ball is in a valve closed position.

7. The valve as defined in claim 4 wherein at least one of the inlet and outlet channels includes an end socket adapted to surround a connecting pipe, and a reservoir in the wall of said channel for trapping solvent and cement used for sealingly joining the connecting pipe to said channels, said reservoir being located betweeen the end of said pipe and the adjacent lip seal member.

8. The valve as defined in claim 1 wherein at least one of the inlet and outlet channels includes an end socket adapted to surround a connecting pipe, and a reservoir in the wall of said channel for trapping solvent and cement used for sealingly joining the connecting pipe to said channels, said reservoir being located between the end of said pipe and the adjacent lip seal member. 45581/2

9. The valve as defined In claim 1 wherein at least one of the inlet and outlet channels includes an end socket adapted to surround a connecting pipe, an abutment surface in said end socket for limiting movement of said pipe toward a lip seal member, and an annular recess in the housing side walls between said abutment surface and the adjacent lip seal member for trapping solvent and cement used for seallngly joining the connecting pipe to said channels.

10. The valve as defined in claim 1 wherein the lip seal member extends radially Inwardly from said adjoining channel by a distance between about 1/lOth and 1/8th inch and has a seat thickness of between about 0.03 and 0.05 inch.

11. The valve seat as defined in claim 2 wherein the lip seal members extend radially inwardly from said adjoining channels by a distance between about 1/10th and 1/8th inch and have a seat thickness at the innermost portion of between about 0.03 and 0.05 inch.

12. The valve as defined in claim 11 wherein the recessed area of the plug is a flattened surface adjacnet the orifice, said flattened surface extending between the periphery of said surface and an outer diameter.

13. The valve as defined in claim 12 wherein the innermost portion of the lip seal member extends radially inwardly beyond said outer diameter and engages said flattened surface when, the valve plug is in the valve open position.

14. The valve as defined in claim 13 wherein at least one of the inlet and outlet channels includes an end socket adapted to surround a connecting pipe, and a reservoir in the wall of said channel for trapping solvent and cement used for sealingly joining the connecting pipe to said channels, said reservoir being located between the end of said pipe and the adjacent lip seal member. 45581/2

15. The valve as defined in claim 1 wherein at least one of -the inlet and outlet channels includes an end socket adapted to surround a connecting pipe, and a reservoir in the wall of said channel for trapping solvent and cement used for sealingly joining the connecting pipe to said channels, said reservoir being located bebetween the end of said pipe and the adjacent lip seal member.

16. The valve as defined in claim 1 wherein at least one of the inlet and outlet channels includes an end socket adapted to surround a connecting pipe, an abutment surface in said end socket for limiting movement of said pipe toward a lip seal member, and an annular recess in the housing side walls between said abutment surface and the adjacent lip seal member for trapping solvent an cement used for sealingly joining the connecting pipe to said channels. surrounding said orifice; a body seal portion formed as a homogeneous part of said housing and being in sealing engagement with portions of the plug remote from said orifice; and an annular lip seal member formed as a homogeneous part of said body seal portion and surrounding said plug orifice, said 45581/2 lip seal member extending radially Inwardly from the periphery j of said adjoining channel to a substantially unstressed position adjacent the periphery of said orifice provide a radially innermost portion having an annular configuration contacting said recessed area when the valve plug is in the valve open position, said radial innermost portion having a substantially uniform thickness in the direction of fluid flow, and said lip seal member further being sufficiently thin in the direction of fluid flow through the valve to form a fluid-tight seal by causing the radially innermost portion of the lip seal member to be displaced in a direction substantially parallel to the direction of fluid flow through the adjacent orifice and to flexingly engage an outer surface portion of the plug when the plug is in valve closed position. 19. The valve as defined in claim 18 wherein the plug is a ball having a substantially spherical shape and the recessed area of the ball is a flattened surface adjacent the orifice, said flat surface extending between the periphery of said orifice and an outer circle. 20. The valve as defined in claim 19 wherein the lip seal member extends radially inwardly from said adjoining channel by a distance between about 1/lOth and l/8th inch and has a seat thickness of between 0.3 and 0.05 inch. 21. The valve as defined in claim 20 wherein the innermost portion of the lip seal member extends radially inwardly beyong said outer circle and engages said flattened surface when the valve ball is in the valve open position. 22. The valve as defined in claim 20 wherein the recessed area of the ball is a smooth curved surface free of sharp edges, and the innermost portion of the lip seal member extends radially inwardly to include an annular ridge which faces the recessed 45581/2 area when the valve ball is in a valve open position and which flexes over the ball surface when the valve ball is in a valve closed position. 23. The valve as defined in claim 20 wherein at least one of the inlet and outlet channels includes an end socket adapted to surround a connecting pipe, and a reservoir in the wall of said channel for trapping solvent and cement used for sealingly joining the connecting pipe to said channels, said reservoir being located between the end of said pipe and the adjacent lip seal member. 24. The valve as defined in claim 18 wherein at least one of the inlet and outlet channels includes an end socket adapted to surround a connecting pipe, and a reservoir in the wall of said channel for trapping solvent and cement used for sealingly joining the connecting pipe to said channels, said reservoir being located between the end of said pipe and the adjacent lip seal member. 25. A valve substantially as described herein with reference to and as illustrated in the accompanying drawings.