Low dead space ring

A ball valve includes a ball member rotatable in a valve chamber and cooperating with a pair of opposed seal assemblies. Each seal assembly comprises a support ring and disc spring having a resilient seal member interposed therebetween. A normally occuring void in the valve chamber is filled through use of a pair of dead space rings. These dead space rings are formed of a rigid, low friction material that does not substantially increase the torque required to rotate the ball member. In addition, the rigid material prevents cold flow of the material into the fluid passageway.

BACKGROUND OF THE INVENTION 
This invention pertains to the valve art, and, more particularly, ball 
valves. The invention is particularly applicable to a new and improved 
ball valve incorporating a low dead space ring and will be described with 
particular reference thereto. However, it will be appreciated that the 
invention has broader applications and could be adapted to use in other 
types and styles of valves. 
Commonly assigned U.S. Pat. Nos. 3,894,718 and 4,410,165 detail the 
evolution and development of seal assemblies utilized in ball valves, the 
disclosures of which are hereby incorporated by reference. Generally, 
early developments of valve seat assemblies for ball valves employed an 
elementary seat design which included a pair of annular plastic seats that 
were compacted between the ball member and the wall portions of end 
fittings. Such seat designs suffered from a number of problems including 
low sealing forces at low pressure or vacuum conditions, and valve leakage 
due to wear and tolerance errors. 
These early seat designs gave way to a contoured seat design in which the 
ball member was engaged along its outer periphery by a narrow band or line 
contact. Wear problems also developed with contoured seat designs and they 
gave way to the development of the flexible seat. The flexible seat, 
though, only provided improved operation for short periods of time. A seat 
ring with a disc spring, as well as an upstream seat bypass arrangement, 
were other improvements developed by the industry which progressively 
overcame various problems associated with ball valve seating arrangements. 
The U.S. Pat. No. 4,410,165 describes a seal assembly which includes a 
support ring, a disc spring, and a seat ring. This assembly provides 
additional seat ring support in a floating ball type of valve which is 
applicable to use in high fluid pressure environments. A longer life span 
was, in turn, realized at a cost savings with respect to other known 
seating arrangements. 
More specifically, the seat assembly structure of the U.S. Pat. No. 
4,410,165 utilizes a pair of resilient seat rings disposed on opposite 
sides of the ball member. A disc spring is interposed between the end 
fittings and the seat rings to continuously urge the seat rings into 
sealing engagement with the ball member. A reinforcing or support ring is 
disposed at a forward surface of each seat ring for positive locating 
engagement with a shoulder extending into the valve chamber. 
Commonly assigned patent application Ser. No. 542,399, now issued as U.S. 
Pat. No. 4,602,762, describes a similar seat ring assembly. It recognizes 
that a reinforcing or support ring need not necessarily be incorporated 
into the valve seal structure. Instead, any bearing surface disposed in 
the valve passageway for abutting engagement with the seat ring may be 
used with equal success. 
These latter two arrangements have proved to be quite satisfactory, but 
after continued use in environments filled with contaminants, the open 
spaces or voids defined between the ball member, seal assemblies, and the 
valve chamber walls are subject to eventual contaminant deposit. This 
contaminant deposit has an adverse effect on the sealing integrity of the 
ball valve. It has, therefore, been deemed desirable to fill these open 
spaces or voids in ball valves to further limit the area available in the 
interior of the valve which could otherwise accommodate fluid flow around 
the ball. Any such arrangement should not interfere with or reduce the 
effectiveness of the seal assemblies themselves. The subject invention is 
deemed to meet these and other needs in providing a new low dead space 
ring construction. 
SUMMARY OF THE INVENTION 
In accordance with the present invention, a valve is provided having a 
valve member disposed for selective movement between open and closed 
positions within a valve chamber. Seal assemblies are disposed on opposite 
sides of the valve member, and each seal assembly is comprised of at least 
a seal ring and a disc spring. The disc spring functions to continuously 
urge the seat ring into the sealing engagement with the valve member. At 
least one dead space ring is adapted for receipt in the area of the valve 
chamber between the valve member, seal assemblies, and the valve chamber 
walls for reducing the volume of the void or open space therein. 
In accordance with another aspect of the invention, the dead space ring has 
a first curvilinear surface adapted for generally mating engagement with 
the valve member. 
In accordance with another aspect of the invention, the dead space ring is 
constructed of a low friction material such as polytetrafluoroethylene or 
the like. 
In accordance with a still further aspect of the invention, the dead space 
ring is constructed of a rigid plastic-like material to limit cold flow 
thereof. 
The principal advantage of the subject invention is the filling of dead 
space within a valve to effectively limit or reduce the open area 
otherwise available in the valve chamber which would accommodate fluid 
flow around the valve member. 
Another advantage of the subject invention resides in a structure for a 
dead space ring which does not cause a substantial increase in the torque 
required to open and close the valve. 
Still other advantages and benefits of the invention will become apparent 
to those skilled in the art upon a reading and understanding of the 
following detailed description.

DETAILED DESCRIPTION OF THE PREFERRED AND ALTERNATE EMBODIMENTS 
Referring now to the drawings wherein the showings are for purposes of 
illustrating preferred and alternate embodiments of the invention only and 
not for purposes of limiting same, FIG. 1 shows a ball valve A having a 
pair of seal assemblies B disposed on opposite sides of a floating-type 
spherical ball or valve member C. The ball member is adapted for selective 
rotation between valve closed and open positions as is well known in the 
art. 
In FIG. 1, the ball valve A includes a body or housing 10 having a central 
opening extending therethrough defining a valve chamber 12. A pair of end 
fittings 14, 16 are situated at opposed ends of the body 10 and include a 
pair of shoulders 18, 20 defined by end faces 22, 24 of the end fittings. 
The end fittings are secured to the body by conventional means such as 
elongated tie bolts 26 and are adapted for retaining the seal assemblies B 
in generally mating arrangement with the ball valve A. One of ordinary 
skill in the art will appreciate that through openings (not shown) are 
included in the respective end fittings generally along longitudinal axis 
1 of the valve body to accommodate fluid communication between the valve 
chamber and an external fluid system or associated piping in a known 
manner. A pair of grooves 28, 30 at opposite ends of the body are open 
axially toward the end fittings and radially toward the seal assemblies 
and receive seal members 32, 34 such as O-rings or the like. In this 
manner, the end fittings and seal assemblies may be placed in sealed 
relationship with the valve body 10. 
A ball member 36 is dimensioned for close receipt within the valve chamber 
12, occupying a major portion of the chamber, and includes an axial 
passage 38 formed therethrough. The ball member is adapted for selective 
rotation about a stem axis m to align the passage 38 with the respective 
through openings formed in the end fittings. As is known, a spade portion 
of a stem 40 is operatively received in a slot or groove 42 formed in the 
ball member. The stem penetrates through the side wall of the body and 
includes a radially extending flange 44 (FIG. 2) cooperable with a 
recessed or counterbalanced area 46 formed in the body to prevent removal 
of the stem outwardly from the body along stem axis m. In addition, flange 
44 provides a lower support for a thrust washer 48. 
With reference again to FIG. 1, stem packing members 56, 58, 60, 62 are 
disposed at axially-spaced intervals about the stem. The lowermost packing 
member 56 may be comprised of a pair of chevron packings which cooperate 
along facing angularly oriented faces. Application of axial pressure to 
the chevron packings thus exerts a tight, radially directed sealing force 
against the stem and body. Packings 56, 58, 60 are supported by a shoulder 
64 formed in the body. Cylindrical metal gland 62 transfers compressive 
forces to the remaining stem packing members supported in the body. An 
analogous stem packing structure and function is detailed in commonly 
assigned U.S. Pat. No. 4,558,874. 
An actuating mechanism 66 is generally shown as comprising a handle member 
68 and includes having a pair of downwardly depending stop surfaces 70, 72 
for predetermined engagement with the exterior of the body 10 at valve 
open and closed conditions. A pair of nuts 74, 76 are threadedly received 
on the stem at lower and upper surfaces of the handle, respectively, for 
placing the stem packing in a proper sealing condition and for clampingly 
retaining the handle member on the stem. It will be understood by one of 
ordinary skill in the art, however, that other types of actuating means 
may be satisfactorily employed without departing from the overall spirit 
or scope of the invention. 
With primary reference to FIG. 2, as well as continued reference to FIG. 1, 
description will be made of the specific details of the seal assemblies B. 
FIG. 2 particularly illustrates a portion of one seal assembly in the 
assembled condition and it will be understood that the following 
description is equally applicable to the other seal assembly unless 
otherwise specifically noted. First, a circumferentially continuous 
shoulder generally designated 80 extends inwardly into valve chamber 12 
from the body 10, and is defined by a first axial surface 82 and second 
radial bearing or support surface 84. Seal assembly B includes a 
reinforcing or support ring 86 having a notch-like first surface 88 
abuttingly engaging radial surface 84 of the shoulder. The support ring 
has a through opening 90 radially spaced from the outer circumference of 
the ball member, and radially oriented end surfaces 92, 94 which are 
substantially parallel to one another. The support ring also includes a 
conical second surface 96 interconnecting the opening 90 and end surface 
92. This conical surface is in generally parallel spaced relation with the 
circumference of the ball member 36. Moreover, support ring end surface 94 
is adapted for abutting engagement with a first surface 98 of a seat ring 
100. 
Alternatively, and as described above with respect to commonly assigned 
application Ser. No. 542,399, now U.S. Pat. No. 4,602,762, a reinforcing 
or support ring 86 need not be incorporated into selected valve 
structures. If the support ring is eliminated, bearing surface 84 will 
necessarily support the seat ring first surface 98 without any adverse 
effect. The remaining description will refer to a valve structure 
utilizing a separate support ring interposed between circumferential 
shoulder 80 and seat ring 100, although one of ordinary skill in the art 
will appreciate that the support ring could be eliminated in certain, 
selected valve arrangements and the remaining structure function in 
substantially the same manner. 
The seat ring 100 is formed of a resilient material such as a plastic or 
plastic-like material. Such, material may, however, vary depending upon 
the specific operating conditions to which the valve will be subjected. 
The seat ring has a through opening 102 disposed radially inward with 
respect to the opening 90 of the support ring 86. A second, generally 
curvilinear surface 104 has a radius of curvature in an unstressed, 
unassembled condition which is greater than the radius of curvature on the 
outer surface of the ball member C. A third surface 106 faces the adjacent 
end fitting 16, and is frustoconical and generally parallel to the seat 
ring first surface 98. The third surface is adapted for engagement with a 
disc spring 114. 
In an uncompressed state, the disc spring 114 has a generally frustoconical 
conformation. When assembled in the ball valve, the disc spring is moved 
toward a substantially flattened condition so that a first radially inner 
portion 116 engages the seat ring at third surface 106 while a radially 
outer portion 118 abuts the shoulder 20 of end fitting 16. The flattened 
condition of the disc spring causes the seat ring 100 to be continuously 
biased into a sealing relationship with the ball member 36 substantially 
along the curvilinear surface 104 in the manner illustrated. 
Repeated openings and closings of the valve, especially in a harsh fluid 
system environment, result in the passage of contaminants into the cavity 
120 (FIGS. 1 and 2) formed between the ball member, valve chamber, and 
seal assemblies. Entry of contaminants into this cavity can restrict or 
reduce proper functioning of the valve. The subject invention provides a 
precise path for the flow of fluid through the valve and prohibits entry 
of fluid into the cavity 120 whereby the effective valve life is extended 
and the valve functions smoothly. 
As illustrated in FIGS. 1 and 2, the cavity 120 is substantially filled 
through use of a pair of identical dead space rings 122. One of the dead 
space rings is shown in detail in FIGS. 3-5 and generally designated by 
numeral 122, it being appreciated that the other dead space ring is 
identical thereto. The dead space rings are comprised of a low friction 
material to limit any increase in torque required for operating the valve 
in view of the presence of such dead space rings. For example, the 
preferred and alternate embodiments of the dead space rings which are 
disclosed herein utilize polytetrafluoroethylene impregnated with 
reinforcing glass or carbon fiber. However, it will be appreciated that 
other materials could also be used to accommodate different operating 
conditions and/or parameters. 
More specifically, the outer surface or circumference 130 of ring 122 is 
designed for close mating receipt by the side wall of the valve chamber 
12. In the preferred embodiment shown, the outer surface of the dead space 
ring has a generally smooth contour and extends from an inner edge 132 to 
a rear shoulder 134. The ring further includes an outer, tapered surface 
136 interposed between shoulder 134 and an outer edge portion 138. As 
particularly shown in FIG. 2, the shoulder 134, tapered surface 136, and 
outer edge portion 138 conform to the end face 92, curvilinear surface 96, 
and opening 90, respectively, of the support ring 86. A central, through 
opening in the ring is defined by a generally curvilinear surface 140 and 
is concentrically spaced from the outer circumference 130 for establishing 
a close mating relationship with the outer surface of the ball member. The 
central opening gradually decreases in size from its largest diameter at 
inner edge 132 to its smallest diameter at outer edge portion 138 (FIG. 
4). The inner edge 132 of the dead space ring shown in FIGS. 3-5 abuts or 
nearly abuts the corresponding edge on the other dead space ring. Also, 
outer edge portion 138 of each dead space ring engages from surface 98 of 
the associated seat ring (FIGS. 1 and 2). An arcuate cutout 142 extends 
through the side wall of the dead space ring. When the cutouts in the pair 
of dead space rings are placed in opposed relation to each other, they 
accommodate the actuating stem of the valve as best shown in FIG. 1. The 
cutouts are designed to closely receive the flange 44. 
With respect to this preferred embodiment of the dead space rings, and upon 
assembly of the ball valve, the dead space rings 122 are initially fitted 
about the ball valve and the seal assemblies B are then placed into the 
valve chamber 12. The end fittings 14, 16 are thereafter placed in 
abutting relationship with the valve body and retained in a valve 
asesmbled condition as by the fasteners 26. Once assembled, the cavity 
120, which was normally left open in the prior art, valves, is now filled 
by the pair of dead space rings. The low frictional material does not 
substantially increase the torque required of an operator in rotating the 
ball member between valve open and closed positions. 
Additionally, the dead space rings are formed of a rigid material so as to 
limit cold flow of the rings into the passageway 38 of the ball member. 
When the valve is closed, the dead space rings must continually span the 
fluid passageway of the ball member. The dead space rings are unsupported 
in spanning the opening and are, therefore, subject to deflection and 
deformation. To minimize the likelihood of deformation, the dead space 
rings are formed of a rigid material such as the impregnated 
polytetrafluorethylene previously identified. This provides extended valve 
life while preventing interference with the mechanism and advantages of 
the seal assemblies disposed in opposed relation to each other on opposite 
sides of the ball member. The overall assembly exhibits a low pressure 
sealing action that compensates for wear of the seal member and prevents 
contaminant entry into the valve chamber void. 
FIGS. 2A and 5A illustrates an alternative embodiment of the previously 
described dead space ring. Here, too, only one seal assembly will be 
described in detail, it being understood that such description applies 
equally to the other seal assembly unless otherwise specifically noted. 
Additionally, for ease of illustration, like elements are identified by 
like numerals with a primed (') suffix and new elements identified by new 
numerals. 
In FIG. 2A, a shoulder 80' includes first and second surfaces 82', 84', the 
second surface 84' adapted for abutting engagement with support ring 86'. 
This support ring is of simpler construction than was described with 
reference to the preferred embodiment, and includes an inner opening 90' 
and end faces 92', 94'. The seat ring 100' and disc spring 114' are of 
identical construction whereby the seat ring is continuously urged into 
engaging, sealing relation with the ball member 36'. 
The alternate dead space ring 122' of FIG. 5A is also of simpler 
construction than that of the preferred embodiment. A smooth outer surface 
130' extends from an inner edge 132' to a rear surface 134'. The rear 
surface 134' abuts the support ring 86' substantially along the end face 
92'. In addition, an arcuate cutout 142' is provided to closely receive 
flange 44' of the actuating stem in the same manner previously described. 
The use and function of this alternative dead space ring also is similar 
to that previously described. 
The invention has been described with reference to preferred and alternate 
embodiments. Obviously, modifications and alterations will occur to others 
upon a reading and understanding of this specification. It is intended to 
include all such modifications and alterations insofar as they come within 
the scope of the appended claims or the equivalents thereof.