CA1050954A

CA1050954A - Plug valve construction

Info

Publication number: CA1050954A
Application number: CA265,929A
Authority: CA
Inventors: Earl A. Bake; E. Frederick Schoeneweis
Original assignee: Rockwell International Corp
Current assignee: Boeing North American Inc
Priority date: 1975-12-02
Filing date: 1976-11-17
Publication date: 1979-03-20
Also published as: AR213187A1; NL7613145A; MX144256A; GB1539824A; FR2334040A1; GB1539825A; GB1539826A; DE2654672A1; CH606889A5; BR7608080A; IT1064535B; AU1951376A; AR211817A1; ES453865A1; AR219504A1; SE7613483L; JPS5269027A; BE848947A; AU512492B2

Abstract

Abstract of the Disclosure An improved plug valve is of the type that includes a valve body having a bore extending therethrough and a pair of passages in-tersecting the bore and being substantially normal to the axis of the bore. a valve plug is disposed within the bore for selective rotation between an opened and a closed position to respectively align and mis-align a port through the plug with the passages. A first circumferential sealing member between the plug and the bore above the port and the passages and a second circumferential sealing member between the plug and the bore below the port prevents fluid from escaping from an interior of the plug valve and balances fluid pressure acting on the plug. The improvements include providing opposed circumferential semicircular grooves respectively on the bore and the plug to define a circumferential channel therebetween. The body includes a circular hole extending therethrough which is tangentially aligned with the channel. A flexible rod extends through the hole and around the channel for retention of the plug within the bore. A bottom insert is fitted within the bore to enclose the base of the plug within the body and allows fluid to escape from below the plug if the second sealing member should fail. A cir-cumferential sealing device around the top of the plug prevents ingress of foreign matter into the region of the bore above the first sealing member.

Description

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IMPROVED PLUG VALVE CONSTRUCTIQN

Background of the Invention Field of the Invention. Th~s invention relates to the con-struction of a plug valve and, more specifically, to a means ~or re-taining the rotatable plug ~ithin the body of the valve and for preventing ingress of dirt or liquid into the interior of the valve.
Description of the Prior Art. There have heretofore been utilized a number of types of plastic plug Yalves for use ln the gas distribution piping field. These valves are co~monly buried underground and exposed to ground water and dirt which could ~nterfere with valve operation. Some valve configurations such as those disclosed in U.S. Patent Nos. 2,505,270,

2,604,293~ 2,844,353, 3,103,948 and 3,133,723 are not su~ted for this environment because the base of the rotatable plug is exposed and could become jammed, preventing its rotation.
While some sealing at the bottom of the body is needed, those found is U.S. Patent Nos. 2,493,966, 3,066,908 and 3,6~7,416 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 could present a problem. Fluid pressure could act on the base of the plug to force it from the body or cause it to b~nd interferring with rotation. This condition is explained in U.S. Patent 3,350,057 which discloses a valve which is, by design, unbalanced. Retention of the plug within the body against the axial force created by the pressure buildup within a closed ~ottom of the body necessitates the use of a sturdy thrust ~asher and associated support structure.
It can also be seen from the various prior art balanced plug valves discussed above that there are a number o~ varied and complex configurations employed to provide a means for retaining the plug against axial movement within the body. Retention i5 obtained in these valves by enclosing the top and bottom of the body; entrapping a top enclosure between the plug and the handle; extendlng a set screw or pin int~ an aligned circumferential 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.

Summary of the_InYention It is an object o~ this invention to provide an improved plug valve having a simple, reliable means for reta~ning the plug within the body oF the plug valve to resist axial movement thereof~
It is another object to provide an ~mproved plug valve having a means for enclosing the base o~ the plug with~n the body wh~le allowing the escape of flu~d pressure from beneath the plug in the bore which m~ght result if seallng below the passages should Fall.
It is yet another object to provide an improved plug valve having sealing around the plug which prevents the ~ngress of foreign material into the ~op 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 palr of passages inter-secting the bore and being substantially normal thereto. A valve plug is d~sposed 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. A ~irst circumferential sealing means between the plug and bore above the port and the passages and a second cir-cumferential sealing means bet~een the plug and the bore below the port and the passages prevent fluid ~rom escaping ~rom an interior o~ the plug valve and balanced fluid pressure acting on the plug. The im-provement includes the bore having a first circumferential semi~circular groove formed in the interior surface thereof. The plug has an opposed . .

~ al5~:)954 circumferential semi-circular groove formed in the outer surface thereof so that the grooves defined a circumferentlal channel between the plug and the bore. The body has a hole extending therethrough and tangentially aligned with the channel for receipt of a flexible rod for extension therethrough and circumferentially around the channel. A bottom insert is installed within the bore below the plug ts enclose the base of the plug within the body. The bottom insert includes means for limiting the fluid pressure acting on the base of the plug if the second sealing means should fail. A circumferential sealing device around the plug prevents the ingress of foreign material into the bore above the first circumferential sealing means. A method for making the improved plug valve is also provided.

Descriptibn of the Draw~ngs ~ 'igure 1 is a fragmentary sect~onal 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.

~- Detailed Description of the Preferred Embodiment As seen in Figure 1, an improved plug valve lû, including various features of the invention, includes a valve body 12 having a bore 12 extending therethrough. A pa~r of flow passages 16 o~ the body 12 intersect the bore 14 and are substantially normal to its axis. A
plug valve 18 is disposed ~ithin 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 fir~t circumferential 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 seal~ng means 22, 24 includes a pair of resil~ently deformable sealing r~ngs located in grooves ~ 3 ~ . . . . . . . . .

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around the plug 18 to make contact with the ;nterior surface 26 of the bore 14. The sealing means 22 and 24 are provided to preYent fluid from escaping from the interior of the plu~ Y~l~e 10 ~nd t~ ~alance fluid pressure acting on the plug 18.
To retain the plug 18 within the bore 14, a first c~rcum-ferential semi-circular groove 28 is formed in the interior surface 26 of the bore 14. An opposed circumferential 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 circumferential channel 32 between the plug 18 and the bore 14, as best seen in Figure 2. The body 12 is prov~ded a circular hole 34 extending therethrough which is tangent~ally aligned .
with the channel 32. Retention is actually obtained 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, axlal 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 U.S. Patent Nos 2,597,482, 6,306,402 and 3,759,553, : the present configuration is particularly adapted to insure that theplug 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 materlal, the rod 36 can also appropriately be formed of plastic. It should be kept in mlnd, however, that the pre-ferred configuration discussed hereinabove might also be utilized in metal valves and/or the rod 36 might alternatlvely 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 applied to the end 38 to cause it to fuse with the body 12, thus sealing the hole 34. Preferably, . 30 rather than direct sealing with the end 38, a sealing plug 40 is utilized.
.~ After the rod 36 is installed with the end 38 at an intermed~ate location . :
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within the hole 34, the sealing plug 40 is inserted in the hole 34 and heat fused to the body 12 to retain the rod 36 therein while sealing the hole 34.
It is also desirable to provide the valve 10 with a means for enclosing the base 42 of the plug 18 within the body 12 to insure proper operation of the valve when it i5 installed underground. A plastic bottom insert 44 is provided for this purpose to be snuggly fitted within the bore 14 belo~ the plug 18. The bottom insert 44 is also designed to limit the fluid pressure which can act on the base 42 of the 0 plug 18 if the second sealing means 24 should fail. Otherwise, failure of the second sealing means 24 might allow fluid pressure to act on the base 42 of the plug 18 to overcome the restraining effect of the rod 36 and axially force the plug 18 from the bore 14. Limiting fluid pressure at the base 42 whlle enclosing the base 42 is accomplished by providing the bottom insert 44 with a plast~c tubular extension 46 wh~ch depends along the interior surface 26 of the bore 14 and is slightly flared outwardly to make resilient contact there~ith. If fluid pressure above the bottom insert 44 were to increase, leakage around tuhular extension 46 would allow its escape.
To properly locate the bottom insert 44 within the bore 14 by limiting the amount of insertion therein, the tubular extension 46 is provided, at its lower periphery, an outwardly extending shoulder 48 ~hich is aligned to make contact with the body 12 around the bore 14.
To insure the bottom insert 44 will be reta1ned within the bore 14 against accidental withdrawal9 the lower periphery of the twbular extension 46 is joined to the body 12 around the bore 14 at a plurality of circumferentially spaced locations SO. The locations are properly separated to insure relief of fluid pressure by movement of the tubular extension 46 if required.
It is also desirable to prevent fluid p~ressure at the top of the valve 10 and to prevent the ingress of forelgn mater~al into the . .

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bore 14 from the top. Accordingly, the improved pluy YalYe 10 includes a simplified, less complicated sealing configuration than the similar device shown in U.S. Application Serial No. 614,207, Sealing Member ~or Valve Stems, filed on September 17, 1~7~ ~y E. F. Shoeneweis and Leonard J. Stephens. The body 12 has a periphery shoulder 52 around the top of the bore 14 and the plug 1~ includes a flared top section 54 adjacent the shoulder 52. The top section 54 and shoulder 52 have opposed surfaces 56 and 58, respectively, thereon which inwardly converge toward a space 60 between the bore 14 and the plug 18 above the first cir-cumferential sealing means 22. A resilient sealing ring 62 encirclesthe plug 18 and normally compressively engages the opposed surfaces 56 and 58 to prevent ingress of foreign material into the space 60. Should the first sealing means 22 fail, fluid pressure in the space 60 would be limited as the sealing ring 62 would be outwardly cleflected 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 confiyuration at any number of locations along the plug while still provid-ing the desired plug retention.

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Claims

WHAT IS CLAIMED IS:

1. An improved plug valve of the type which includes a valve body having a bore extending therethrough and a pair of passages inter-secting said bore and being substantially normal to an axis of said bore; a valve plug disposed 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 cir-cumferential 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 prevent fluid from escaping from an interior of said plug valve and to balance fluid pressure acting on said plug; wherein said improvement comprises:

said bore having a first circumferential semi-circular groove formed in the interior surface thereof;

said plug having an opposed circumferential semi-circular groove formed in the outer surface thereof, said first groove and said opposed groove defining a circumferential channel between said plug and said bore;

said body having a circular hole extending therethrough and tangentially aligned with said channel; and a flexible rod loosely conforming in cross section to said channel extending through said hole and cir-cumferentially around said channel.

2. The improved plug valve as set forth in Claim 1 wherein said rod includes an end terminating at an intermediate location within said hole, further including means for sealing said hole exteriorly of said end of said rod.

3. The improved plug valve as set forth in Claim 2, wherein said body, said plug and said rod are formed of plastic and said means for sealing said hole includes a plastic member fused to said body.

4. The improved plug valve as set forth in Claim 1 wherein said rod is plastic and includes an end which is fused to said body to seal said hole.

5. An improved method of making a 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 disposed 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 prevent fluid from escaping from an interior of said plug valve and to balance fluid pressure acting on said plug; wherein said improvement comprises:

forming a first circumferential semi-circular groove in the interior surface of said bore;

forming an opposed circumferential semi-circular groove in the outer surface of said plug, said first groove and said opposed groove defining a circumferential channel between said plug and said bore;

providing a circular hole through said body in tangential alignment with said channel; and inserting a flexible rod which loosely conforms in cross section to said channel through said hole and circumferentially around said channel.

6. The improved method of making a plug valve as set forth in Claim 5, further including sealing said circular hole after inserting said flexible rod.