Note: Descriptions are shown in the official language in which they were submitted.
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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
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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
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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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