Plug valve

A gas distribution valve including a body defining an inlet and an outlet passage, a central well containing a cylindrical plug disposed for arcuate displacement therein and including a transverse thru-bore that can be rotated into and out of axial alignment with the flow passages of said body for opening and closing the valve respectively. Overmolded elastomeric seat seals are provided for superior sealing that are urged against the well walls by an arcuate leaf spring intervening between the seals and the plug and extending in a direction concentric with the plug. A cover plate secures the plug within in the well and there is afforded a fire seal ring providing bi-directional contact sealing operative to restrict gas flow during and after exposure to fire or other high temperature environment.

FIELD OF THE INVENTION 
The field of art to which the invention pertains includes the art of plug 
valves utilized in a piping system for controlling flow of fluid line 
content. 
BACKGROUND OF THE INVENTION 
Valves of the type to which the invention is directed are sometimes termed 
"meter and curb valves" or "plug valves" and have been commercially 
available for many years. They have been widely utilized in pipeline flow 
containing natural gas or other fluid substances. A common construction, 
employs a tapered plug valve arcuately operable in a conical body well. A 
biasing member such as a spring or the like forces the plug axially 
downward within the well. The body includes inlet and outlet passages 
separated by the well. For purposes of regulating flow, the plug includes 
a lateral thru-port alignable with the body passages. Valve operation 
comprises arcuately displacing the plug to either align or offset the 
thru-port of the plug with respect to the axis of the body flow passages. 
Exemplifying such valves are the disclosures of U.S. Pat. Nos. 3,360,236 
and 3,806,087. 
While such valves have functioned well, they are generally characterized as 
not being cost effective from the standpoint of manufacturing costs, are 
not inherently fire resistant, have less than optimum flow 
characteristics, tend to have higher than anticipated operating costs and 
require a modest amount of lubrication over the operating life of the 
valve. 
OBJECTS OF THE INVENTION 
It is therefore an object of the invention to provide a novel gas 
distribution valve that is increasingly cost effective to manufacture 
compared to similar purpose valves of the prior art. 
It is a further object of the invention to effect the previous object in a 
gas distribution valve of relatively smaller size than heretofore without 
sacrifice in flow capacity characteristics. 
It is a still further object of the invention to effect the previous 
objects with a valve operably characterized to restrict leakage of flow in 
response to a high temperature exposure or fire condition. 
SUMMARY OF THE INVENTION 
This invention relates to a novel construction for a gas distribution 
valve. More specifically, the invention hereof relates to a cost effective 
construction for a gas distribution valve while affording attributes not 
previously contained in like valves of the prior art. 
The foregoing is achieved in accordance with the invention by a gas 
distribution valve having a relatively smaller body mass per unit size 
while defining inlet and outlet passages separated by a central well. An 
arcuately displaceable cylindrical plug is disposed in the well and 
includes a transverse bore that can be arcuately displaced ninety degrees 
into and out of alignment with the body flow passages for opening and 
closing the valve respectively. 
Over-molded elastomeric seat seals supported by the plug afford superior 
sealing and are biased outward by a leaf spring extending arcuately in a 
direction concentric with the plug. The spring in this relationship 
affords enhanced sealing by the seat seals against leakage in the closed 
position of the valve. A friction ring enables relatively low displacement 
torques for the plug while a fire sealing ring provides a bi-directional 
seal operative to restrict leakage flow outward of the bonnet following 
exposure to fire or other high temperature environment. 
The above noted features and advantages of the invention as well as other 
superior aspects thereof will be further appreciated by those skilled in 
the art upon reading the detailed description that follows in conjunction 
with the drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
In the description which follows, like parts are marked throughout the 
specification and drawings with the same reference numerals respectively. 
The drawing figures are not necessarily to scale and in certain views, 
parts may have been exaggerated for purposes of clarity. 
Referring now to the drawings, the valve hereof is designated 10 and is 
comprised of a body 12 containing a centrally located cylindrical well 14 
for receipt of an arcuately displaceable cylindrical plug 16. Opposite 
flanges 18 and 24 enable installation into a piping system with which the 
valve is to be utilized. Optionally, the flanges can be omitted and the 
ends adapted for welding or threading. 
Transversely communicating inward through flange 18 is an inlet passage 22 
terminating in an inlet port at well 14 whereas communicating outward from 
outlet port 25 to flange 20 is an outlet passage 24. Within plug 16 is a 
transverse thru-port 26 which when axially aligned between inlet 22 and 
outlet 24 places the valve in the "open" position whereas when offset 
ninety degrees with respect thereto places the valve in the "closed" 
position. For reasons as will be explained, the diameters and geometric 
configuration of ports 23 and 25 are the same as that of thru-port 26. 
Supported on or about plug 16 are opposite arcuate leaf springs 28 to be 
received in opposite plug recesses 30 and a seat pad 32 likewise received 
in recess 30 behind spring 28. Pad 32, as will be further explained, seals 
against leakage when the plug is in its closed position. Also supported on 
plug 16 is a primary gas seal 34, a friction ring 36, a concentrically 
rippled or corrugated stainless steel fire seal 38, and a weather seal 40 
all of which are secured in place by a cover plate 42 secured via bolts 44 
to body 12. A locking plate 46 positioned over the wrench stem 48 of the 
plug enables the open or closed positions of the valve to be set and 
secured by a bullet lock (not shown) inserted in plate aperture 49 and 
extending through one of lobe apertures 51 or 53. 
Body 12 is preferably comprised of cast ductile iron or steel and in order 
to reduce the amount of metal mass otherwise required for maintaining 
strength includes a longitudinal rib 50 extending between outer flanges 18 
and 20. Stem or plug 16 is likewise preferably of cast ductile iron or 
steel formed essentially of cylindrical configuration for receipt within 
cylindrical well 14. Comprising the plug are vertical recesses 30 on 
opposite surfaces ninety degree offset from the axis of thru-port 26 for 
receipt of spring 28 and seat pad 32. Above the thru-port, the plug 
includes an annular recess 52 in which to receive primary gas seal 34 and 
a shoulder 54 on which to receive friction ring 36 and fire seal 38. 
Annular recess 56 receives weather seal 40 and serves to prevent water 
entry into the valve and thereby prevent the possibility of freezing 
and/or corrosion as might otherwise occur. Lateral stub 58 serves to 
engage ninety degree stops (not shown) on the underside of top plate 42 
for limiting arcuate displacement of the plug between open and closed 
positions. 
Comprising the valve seats hereof for effecting a gas tight seal with the 
plug in the closed position, are the seat pads 32 comprised of a moon 
shape arcuate metal segment 60 onto which a high tensile strength 
elastomer 62 such as urethane or rubber has been molded on its backside. 
The elastomer for this purpose includes continuous and parallel ribs 64 
and 66 adjacent its peripheral edge. The elastomer seals, likewise 
eliminate the prior art use of grease for lubrication and seal 
enhancement. Positioned intervening between each seat pad and the inner 
surface 72 of recess 30 is arcuate leaf spring 28 arranged concentrically 
with respect to the axis of plug 16 and having radial feet 68 and 70 that 
seat against inner recess surface 72. When installed and operative, spring 
28 is compressed inwardly so as to urge the seat pads 32 outwardly. 
The seat pad 32 is dimensioned both arcuately and in height sufficient when 
installed to span the inlet and outlet ports 23 and 25 thereat. The 
elastomeric ribs 64 and 66, with the plug in its closed relation, will 
thereby be urged outward by compressed spring 28 to engage the wall 
surface of well 14 thereabout for effecting a closure seal. In the course 
of the stem being rotated ninety degrees for opening of the valve, seal 
pads 32 will ride in recesses 30 in the course of plug displacement 
without separating from the wall surface of well 14. 
The selected radius on the back of seat pad 32 being urged by spring 28 
against the well surface is oriented concentrically with respect to the 
well surface allowing a lower profile and a more economical design in 
that, cylindrical well 14 and plug 16 can be smaller for a given flow 
requirement. At the same time by virtue of the venturi cross section of 
the inlet and outlet passages communicating thereat, a greater flow 
efficiency of more flow or at least the same flow through a smaller valve 
if effected. That is, the venturi design of inlet 22 has the effect of 
reducing pressure drop such that with an inlet port 23 that matches 
thru-port 26 in size, greater flow than otherwise is effected. 
Also contributing virtue to the valve hereof is the fire seal 78 effected 
intervening between body 12, plug 16 and cover plate 42 by friction ring 
36 and fire seal ring 38 as best seen in FIG. 3A. It will be appreciated 
that as bolts 44 are tightened, a compression loading is imposed between 
the body and top plate compressing and expanding the corrugated or rippled 
fire seal ring 38 so as to consume any clearance in the gap spacing about 
shoulder 54. The effect thereof is to minimize or eliminate the ability of 
gas content to leak outward through the bonnet to atmosphere even 
following exposure to fire or other high temperature source. At the same 
time, any gas pressure applied to the valve stem urges the stem upward in 
the direction toward the top plate thereby enhancing the pressure loading 
between the stem and top plate and imposing an increased sealing squeeze 
against the fire seal ring. Friction ring 36 comprises a polymer 
incorporating a lubricant such as molybdenum disulphide. Use of the 
friction ring affords the benefit of minimizing if not eliminating a 
future need to lubricate the valve. That is, once the elastomer burns away 
from seat pads 32 a metal to metal seal is instantly created. 
By the above description there is disclosed a novel gas distribution valve 
having a construction affording many virtues over similar type valves of 
the prior art. A reduced body size along with a cylindrical, (or 
elliptical) rather than a tapered plug, enables a smooth turbulent free 
thruput and a venturi flow path whereby the same or more flow can be 
achieved in a relatively smaller valve. The seat pads are supported in 
pockets formed in opposite surfaces of the plug 16 ninety degrees 
displaced from the axis of the thru-port 26. Construction of the seat pads 
is such as to provide rotational guidance to the plug while at the same 
time being urged outwardly against the wall surfaces of the plug well 
thereat to effect a positive seal against leakage in the closed position 
of the valve. In the event a fire is encountered which destroys the 
elastomer, a restrictive flow is still maintained by the spring force 
urging the seat into contact against the well surface thereby minimizing 
the possibility of leakage and continuing to render the valve 
substantially leakage free. 
Since many changes could be made in the above construction and many 
apparently widely different embodiments of this invention could be made 
without departing from the scope thereof, it is intended that all matter 
contained in the drawings and specification shall be interpreted as 
illustrative and not in a limiting sense.