CA1065830A - Plug valve construction - Google Patents

Abstract

Abstract of the Disclosure An improved plug valve of the type which includes a valve body having a bore extending therethrough and a pair of passages intersecting the bore and being substantially normal to an axis of the bore is disclosed.
A valve plug is disposed within the bore for selective rotation between an opened and a closed position to respectively align and misalign a port through the plug with the passages. First circumferential sealing means is disposed between the plug and the bore above the port and the passages. A
second circumferential means is located between the plug and the bore below the port and the passages to prevent fluid from escaping from an interior of the plug valve and to balance fluid pressure acting on the plug. The improvement according to the invention resides in a bottom insert snuggly fitted within said bore below said plug to enclose a base of said plug within said body. The bottom insert includes means for limiting said fluid pressure acting on said base of said plug if said second sealing means should fail by allowing escape of said fluid to the exterior of said body from said bore below said plug.

Description

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This inven~ion relates to the construction of a plug valve and, more specifically, to a means for retaining the rotatable plug within the body of the valve and for preventing ingress of dirt Or liquid into the interior of the valve. This application is a division of Application Serial Number 265,929, filed November 17,1976. .
There have heretofore been utilized a number of types of plastic plug valves for use in the gas distribution piping field. These valves are commonly buried underground and exposed to ground ~ater and dirt which could i interfere with valve operation. Some valve configurations such as those disclosed in United States Patent Nos. 2,505,270, 2,604,293, 2,844,353, 3,103,9~8 and 3,133,723 are not suited for this environment because the base of the rotable plug is exposed and could become jammed, preventing its rotation.
While some sealing at the bottom of the bod~ is needed, those found i~ United States Patent Nos. 2,493,966, 3,066,908 and 3,687,416 either complicate body or plug formation or are relatively expensive to provide.
Further, although these valves are purportedly balanced by sealing rings around the plug above and below the flow passages, if the lower seal were to fail, having a pressure-tight area below the plug cuuld present a problem.
20 Fluid pressure could act on the base of the plug to force it from the body or cause it to bind interfer:Lhg with rotation. This condltion i~ e~plained in Unitcd States Patent 3,350,0S7 which disoloses a ~alve which i9, by design, unbalanced. ~etention of the plug within the body against the axial force created by the pressure buildup within a closed bottom of the body necessitatcs the use of a sturdy thrust washer and associated support structure.
It can also be seen from the various prior art balanced plug valves discussed above that there are a number of varied and complex ~ .

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configurations employed to provide a means for retaining the plug against axial movement within the body. Retention is obtained in these valves by en-closing the top and bottom of the ~body; entrapping a top enclosure between the plug and the handle; extending a set screw or pin into an aligned circumferen-tial groove; using a pair of snap rings at the exposed top and bottom of the plug; or threading the plug into the bottom of the body.
It is an object of this invention to provide an improved plug valve having a simple, reliable means for retaining the plug within the body of the plug valve to resist axial movement thereof.
It is another object to provide an improved plug valve having a means for enclosing the base of the plug within the body while allowing the escape of fluid pressure from beneath the plug in the bore which might result if sealing below the passages should fail.
It is yet another object to provide an imp ~ved plug valve having sealing around the plug which prevents the ingress of foreign material into the top of the bore.
These and other objects are provided in a preferred embodiment in the form of an improved plug valve of the type which includes a valve body having a bore extending therethrough and a pair of ~assages inters~cting the bore and 'being substantially normal thereto. A valve plug is disposed w:ithin the bore for selective rotation between an opened ancl a closed position to ,, respectively align and misalign a port through the plug with the passages.
A first circumferential sealing means between the plug and bore above the port and the passag~s and a second circumferential sealing means between the plug and the bore below the port and the passages prevent fluid from escaping from an interior of the plug valve and balanced fluid pressure acting on the plug. The improvement includes a 'bottom insert is snugly fitted within'the bore below the plug to enclose the base of the plug within the body. The '"
bottom insert includes means for limiting the fluid pressure acting on the

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base of the plug if the second sealing means should fail by allowing escape of ! ', ~
said fluid to the exterior of said body from said bore below said plug. A
method for making the improved plug valve is also provided.
Figure 1 is a fragmentary sectional side view of the preferred plug -valve including various features of the invention;
Figure 2 is a view of the plug valve of Figure 1 as seen along line 2-2.
As seen in Figure 1~ an improved plug valve 10, including various features of the invention, includes a valve body 12 having a bore 12 extending therethrough. A pair of flow passages 16 of the body 12 intersect the bore 14 and are substantially normal to its axis. A plug valve 18 is disposed within the bore 14 for selective rotation by a handle 19 between an opened and a closed position to respectively align and misalign a port 20 through the plug 18 with the passages 16. The plug valve 10 further includes first circumfer-enkial sealing means 22 between the plug 18 and the port 14 above the port 20 and passages 16 and second circumferential sealing means 24 therebetween below the port 20 and passages. In the preferred embodiment, each sealing means 22, 2~ includes a pair of resiliently deformable sealing rings located in grooves around the plug 18 to make contact with the interior surface 26 of the bore 14.
The sealing means 22 and 2~ are provided to prevent fluid from cscaplng from the interior of the plug val~e lO and to balancc fluid pressure acting on the plug 18. , To retain the plug 18 within the bore 14, a first circumferential semi-circwlar groove 28 is formed in the interior surface 26 of the bore 14.
An opposed circumferent~al semi-circular groove 30 is also formed in the outer surface of the plug 18 so that the groove 28 and the groove 30 defined a cir-cumferential channel 32 between the plug 18 and the bore 14, as best seen in Figure 2. The body 12 is provided a circular hole 34 extending therethrough which is tangentially aligned with the channel 32. Retention is actually ob-.... . .. . . . . . . . . .
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tained by inserting a flexible rod 36, which loosely conforms in cross section to the channel 32, into the hole 34 and circumferentially around the channel 32. As the rod 36 makes contact between the plug 18 and the bore 14, axial movement of the plug 18 with respect to the bore 14 is prevented.
Although this method of retention is similar to the pipe coupling means shown in United States Patent Nos. 2, 597, 482, 6, 306, 402, and

3,759~ 53, the present configuration is particularly adapted to insure that the plug 18 is free to rotate within the bore 14 for proper operation of the valve 10. Since the preferred plug valve 10 includes a plug 18 and body 12 formed of plastic material, the rod 36 can also appropriately be formed of plastic~ It should be kept in mind, however, that the preferred configuration discussed hereinabove might also be utilized in metal valves and/or the rod 36 might alternatively be formed of metal. However, in the preferred plastic configuration, an end 38 of the plastic rod 36 is located interiorly of the hole 34. To maintain the integrity of the valve body :12, heat could be ap-plied to the end 38 to cause it to fuse with the body 12, thus sealing the hole 34. Preferably, rather than direct sealing with the end 38, a seal-ing :
plug 40 is utilized. After the rod 36 is installed with the end 38 at an in- :
termediate location within the hole 34, the sealing plug 40 is inse;cted in the hole 34 and heat fused to the body :l2 to retain the rod 36 therein wh:ile sealing the hole 34, It :i~ also desirab~e to p~ovide the val~e .lO wi.th a means ~or en-closing the base 42 of the plug 18 within the body 12 to insure proper opera-tion of the valve when it is installed underground. ~ plastic bottom inser~
44 .L9 pro~.ided for this purpose to be snugly ~itted within the bore 14 below the plug 18. The bottom insert 44 is also designed to li~-it the fluid pres-sure which can act on the base 42 of the plug 18 if the second sealing means :.
24 should fail. Otherwise, ~ailure of the second sealing means ~4 might al-low fluid pressure to act on the base 42 of the plug 18 to overcome the re-_4_ ~6583(~
straining effect of the rod 36 and axially force the plug 18 from the bore 14.
Iimiting fluid pressure at the base 42 while enclosing the base 42 is accom~
plished by providing the bottom insert 44 with a plastic tubular extension ~;
46 which depends along the interior surface 26 of the bore 14 and is slightly flared outwardly to make resilient contact therewith. If fluid pressure above the bottom insert 44 were to increase, leakage around tubular extension 46 would allow its escape.
- To properly locate the bottom insert 44 within the bore 14 by limit-ing the amount of insertion therein, the tubular extension 46 is provided, at its lower periphery, an outwardly extending shoulder 48 which is aligned to ~
make contact with the body 12 around the bore 14. To insure the bottom insert -44 will be retained within the bore 14 against accidental withdrawal, the lower periphery of the tubular extension 46 is joined to the body 12 around the bore 14 at a plurality of circumferentially spaced locations 50. The locations are properly separated to insure relief of fluid pressure by move-ment of the tubular extension 46 if required.
It is also desirable to prevent fluid pressure at the top of the ;
valve 10 and to prevent the ingress of foreign material into the bore 14 from the top. Accordingly, the improved plug valve 10 includes a simplified, less complicated seaiing configuration than the sirLilar device shown in United States ~ppLication Serial No. 614,207, Sealing Member for Valve Stems, filed on September l7, l975 by ~ Shoeneweis and Leonard J. Stephcns. Tlle body 12 has a periphery shoulder 52 around the top of the bore 14 and the plug 18 includes a flared top section 54 adjacent the shoulder 52. The top section 54 and ~houlder 52 have opposed surEaces 56 and 58, respectively, thereon which inwardly converge toward a space 60 between the bore 1~ and the plug 18 above the first circumferential sealing means 22. A resilient sealing ring ~2 encircles the plug 18 and normally compressively engages the opposed surfaces 56 and 58 to prevent ingress of foreign material into the space 60.

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Should the first sealing means 22 fail, fluid pressure in the space 60 would be limited as the sealing ring 62 would be outwardly deflected to allow its escape. While there has been shown a preferred embodiment of the invention, it should be apparent that various elements or materials might be altered without departing from the scope of the invention as claimed. For example, it can be seen that the plug might be a tapered plug rather than a cylindrical plug as shown in the figures. It would also be possible, for example, to axially relocate the rod-channel configuration at any number of locations along the plug while still providing the desired plug retention.

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Claims (4)

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

1. An improved plug valve of the type which includes a valve body having a bore extending therethrough and a pair of passages intersecting said bore and being substantially normal to an axis of said bore; a valve plug dis-posed within said bore for selective rotation between an opened and a closed position to respectively align and misalign a port through said plug with said passages; and first circumferential sealing means between said plug and said bore above said port and said passages and second circumferential sealing means between said plug and said bore below said port and said passages to pre-vent fluid from escaping from an interior of said plug valve and to balance fluid pressure acting on said plug; wherein said improvement comprises a bot-tom insert snugly fitted within said bore below said plug to enclose a base of said plug within said body, and said bottom insert including means for lim-iting said fluid pressure acting on said base of said plug if said second sealing means should fail by allowing escape of said fluid to the exterior of said body from said bore below said plug.

2. The improved plug valve as set forth in Claim 1, wherein said means for limiting said fluid pressure includes a plastic tubular extension of said bottom insert, said extension depending along an interior surface of said bore and being slightly flared outwardly to make resilient contact therewith.

3. The improved plug valve as set forth in Claim 2, wherein said tub-ular extension of said bottom insert includes an outwardly extending shoulder at its lower periphery aligned to make contact with said body around said bore to limit the amount of insertion of said bottom insert into said bore.

4. The improved plug valve as set forth in Claim 2, wherein said tub-ular extension of said bottom insert includes a lower periphery which is joined to said body around said bore at a plurality of circumferentially spaced locations to secure said bottom insert within said bore.