Floating ball valve with improved valve seat

A ball valve includes a valve body, a ball chamber within the valve body and a valve ball within the ball chamber. The ball valve further includes valve seats in contact with the valve ball. Each valve seat includes a front face, a rear face and an outer face. The front face includes two or more low pressure contact rings and two or more high pressure contact rings that provide enhanced sealing against the valve ball under both high and low pressure conditions. The rear and outer face each include independent seal zones.

FIELD OF THE INVENTION

This invention relates generally to ball valves, and more particularly, but not by way of limitation, to an improved valve seat for a ball valve or any valve utilizing a spherical surfaced closure mechanism.

BACKGROUND

For many years, ball valves have been used in control applications in a large variety of industrial applications. Generally, a ball valve includes a valve body and a rotatable valve ball. The valve ball includes a central port that permits fluid flow through the valve body when the valve ball is rotated into an open position. When the valve ball is rotated into a closed position, the central port is no longer aligned with the inlet and outlet of the valve body and flow is blocked. The rotational position of the valve ball is typically manipulated with a handle that is connected to the valve ball with a valve stem. Most ball valves are intended for bidirectional fluid flow, such that the inlet and outlet of the valve body may be interchangeable.

To prevent leakage around the closed valve ball, valve seats are placed in the valve body in contact with valve ball. Valve seats may be manufactured from metal alloys, polymers and ceramics. Prior art valve seats tend to include a substantially smooth sealing face that matches the exterior contour of the valve ball. In other designs, the valve seat may include a series of grooves that are intended to capture particulates that might otherwise accelerate wear if trapped against the face of the valve seat.

Some prior art valve seats seal effectively under elevated pressures, but perform poorly under lower pressures. In particular, the upstream valve seat may lose a sealing interface with the valve ball when pressure forces the valve ball to deflect downstream within the valve body. The reduced sealing capacity of the upstream valve seat may permit particulates to become entrapped within or behind the upstream valve seat, thereby accelerating wear on the valve seat and increasing torque required to open and close the valve. Particulates as well as normal wear of the seat play a role in degrading and compromising the valve seat's ability to isolate pressurized and flowing fluids between the upstream and downstream connections. Redundant sealing features are critical in extending the useful life of a valve seat. There is, therefore, a need for an improved valve seat design that seals effectively under both high and low pressures and provides redundant sealing surfaces. It is to these and other objectives that the present invention is directed.

SUMMARY OF THE INVENTION

In one embodiment, the present invention includes a ball valve that has a valve body, a ball chamber within the valve body and a valve ball within the ball chamber. The valve ball has an outer surface and a central port extending through the valve ball. The ball valve further includes a valve seat in contact with the outer surface of the valve ball. The valve seat has a front face, a rear face and an outer face. The front face includes two or more low pressure contact rings and two or more high pressure contact rings.

In another aspect, the present invention includes a ball valve that has a valve body, a ball chamber within the valve body and a valve ball within the ball chamber. The valve ball has an outer surface and a central port extending through the valve ball. The ball valve further includes a valve seat in contact with the outer surface of the valve ball. The valve seat has a front face, a rear face and an outer face. The front face includes at least one low pressure contact ring and at least one high pressure contact ring. The at least one low pressure contact ring and at least one high pressure contact ring extend off the front face at different heights.

In yet another aspect, the present invention includes a ball valve that has a valve body, a valve ball and an upstream valve seat. The valve body has a ball chamber, an upstream valve seat pocket and a downstream valve seat pocket. The valve ball is contained within the ball chamber and the valve ball includes an outer surface and a central port extending through the valve ball. The upstream valve seat is located in the upstream valve seat pocket and is in contact with the outer surface of the valve ball. The upstream valve seat has a front face, a rear face, an outer face and a rear corner. The front face has two or more low pressure contact rings and two or more high pressure contact rings. The rear face and the outer face extend away from the rear corner at an obtuse angle such that the rear corner is spaced apart from the upstream valve seat pocket.

WRITTEN DESCRIPTION

Referring first toFIGS. 1 and 2, shown therein are perspective and cross-sectional views, respectively, of a ball valve100constructed in accordance with exemplary embodiments of the present invention. The ball valve100includes a two-piece valve body102that has a first side104and a second side106. The first side104and second side106can be held together with fasteners108. In some embodiments, the first side104and second side106are configured for a mating threaded engagement.

The first and second sides104,106include fluid connections110,112, respectively. It will be appreciated that the ball valve100is configured for bidirectional fluid flow, such that fluid may enter the ball valve from either the first side104or the second side106. Accordingly, as used in this disclosure, the relative positions of components within the ball valve100will be described in terms of “upstream” or “downstream” based on the direction of fluid flow through the ball valve100. A valve body seal114may be included between the first and second sides104,106of the ball valve100.

The first and second sides104,106include valve seat pockets116,118, respectively. The first and second sides104,106also cooperate to define an interior ball chamber120. As illustrated inFIG. 2, the valve seat pockets116,118are contiguous with the ball chamber120. The first side104also includes a valve stem chamber122that provides access to the ball chamber120.

The ball valve100also includes a valve ball124, first and second valve seats126, valve stem128and a position stop130. The valve stem128extends from the position stop130through the valve stem chamber122to the valve ball124. Although the valve stem128can be manually-operated via a handle or wrench, it will be appreciated that the valve stem128can also be an automated via a motorized control valve.

The first and second valve seats126are positioned within the first and second valve seat pockets116,118. Unless otherwise indicated, the first and second valve seats126are similar or substantially identical. The valve ball124is captured in the ball chamber120between the first and second valve seats126. The valve ball124includes a central port132that permits fluid flow between the first and second fluid connections110,112when the valve ball124is rotated into a position in which the central port132is axially aligned with the first and second fluid connections110,112(as depicted in FIG.2). When the valve ball124is rotated approximately 90°, the central port132is no longer aligned and the solid surfaces of the valve ball124prevent fluid flow through the valve body102.FIGS. 3 and 4provide a perspective and cross-sectional views, respectively, of the valve ball124, valve seats126, valve stem128and position stop130.

Turning toFIGS. 5-7, shown therein are perspective and cross-sectional views of one of the valve seats126. As noted inFIG. 5, the valve seat126is a substantially toroidal form that includes a generally triangular cross-section that has a front sealing face134, an outer face136and a rear face138noted inFIG. 7. In exemplary embodiments, the valve seat126is manufactured from durable natural or synthetic engineered polymers or thermoplastics. Suitable plastic materials include Acetal, Nylon, PTFE, PFA, PEEK as well as elastomers such as FKM and Buna-N. The valve seats126can be formed by extrusion, molding, machining and additive manufacturing processes.

The outer face136and rear face138extend from a common rear corner140to opposite ends of the front face134. In the embodiment depicted, the outer face136and rear face138extend from the rear corner140at an obtuse angle. The outer face136and rear face138intersect the front face134acute angles. In this way, the outer face136and rear face138together present a cross section that is slightly incongruent and offset from the substantially square valve seat pockets116,118such that the rear corner140is held off the interior corner of the valve seat pockets116,118(as illustrated inFIG. 2). With this geometry, the outer face136has an outer face contact zone142that is near the front face134and spaced apart from the corner140. The rear face138has a rear face contact zone144that is near the opposite side of the front face134and spaced apart from the corner140.

As shown inFIG. 2, under normal conditions, the valve seats126contact the valve seat pockets116,118at the outer face contact zone142and rear face contact zone144, thus creating a small void behind the valve seat126. Particulate solids that pass near the outer face contact zone142and rear face contact zone144are isolated from the void behind the valve seat126to prevent accelerated wear on the front face134of the valve seat126and to prevent damage to the seat pockets116and118. In exemplary embodiments, the valve seat126has a size and thickness that causes the valve seat126to be slightly compressed between the low pressure contact rings146and the outer and rear face contact zones142,144when the ball valve100is in the open condition. The geometry and elastic construction of the valve seat126produce a spring force that acts against the valve ball124.

The front face134is uniquely contoured to provide enhanced sealing under a variety of pressures. The front face134includes at least two low pressure contact rings146, at least two high pressure contact rings148and three or more channels150. In the embodiment depicted inFIGS. 5-7, the valve seat126includes a pair of low pressure contact rings146that are surrounded by a pair of high pressure contact rings148. In the embodiments depicted inFIGS. 5-7, the low pressure contact rings146extend from the front face134by a first height (h1). The high pressure contact rings148extend from the front face135by a second height (h2) that is less than the first height (h1). In other embodiments, the high pressure contact rings148are disposed between low pressure contact rings146. In yet other embodiments, the low pressure contact rings146and high pressure contact rings148are positioned in an alternating fashion on the front face134of the valve seat126.

As shown inFIG. 7, the low pressure contact rings146and high pressure contact rings148have a rounded apex that provides a line-focused point of contact against the valve ball124that multiplies the sealing pressure produced by the front face134. In exemplary embodiments, the low pressure contact rings146and high pressure contact rings148are formed as a unitary part of the valve seat126.

The channels150are formed between each of the high pressure contact rings148and low pressure contact rings146. The channels150in the front face134are swept or contoured without edges to reduce the risk of particulate entrapment, which may accelerate surface degradation of the ball seal. In the event of particulate entrapment, the recessed surface of the channels150ensure that particulates are isolated from the sealing rings146and148. This reduces the risk of damage to the low and high pressure contact rings146,148. The particulates can be flushed from the channels150in the valve seat126during subsequent articulation of the valve ball124.

Turning toFIGS. 8-11, shown therein are top, cross-sectional depictions of the engagement between the valve seats126and the valve ball124under various pressure conditions caused by the opening and closing of the valve ball124.FIG. 8depicts the upstream valve seat126and valve ball124when the ball valve100is in an open condition.FIG. 9depicts the same valve seat126when the ball valve100is in the closed position.FIG. 10depicts the downstream valve seat126and valve ball124when the ball valve100is in an open condition.FIG. 11depicts the downstream valve seat126when the ball valve100is in the closed position and deflected against the downstream valve seat126under pressure.

In the open condition depicted inFIG. 8, the outer face contact zone142and rear face contact zone144support the valve seat against the upstream valve seat pocket116such that a small void is formed behind the rear corner140of the valve seat126. The low pressure contact rings146of the valve seat126are in contact with the valve ball124to prevent fluid flow around the valve ball124.

InFIG. 9, the ball valve100has been closed. In this condition, the valve ball124tends to deflect downstream in response to the application of upstream pressure. The valve seat126within the upstream valve seat pocket116remains in a relatively uncompressed state as the ball valve100is closed. Unlike prior art valve seats, however, the contoured front face134of the valve seat126remains in contact with the valve ball124and seat pocket116at seal zones142and144under this condition, thereby preventing leakage around the valve ball124and isolating the seat pocket116from particulates while the ball valve100is closed. The low pressure contact rings146provide a focused application of pressure against the valve ball124that enhances the sealing action of the valve seat126, even when the valve seat126is not exposed to elevated pressures.

An important feature of the upstream seat126is the ability to automatically release pressure under high pressure conditions. The enhanced sealing created by engagement of the high pressure and low pressure contact rings148,146with the valve ball124may increase the torque required to articulate valve ball124, particularly when the upstream valve seat126is exposed to elevated pressures. To reduce the torque demands under these conditions, the upstream valve seat126is configured flex away from the valve ball124at the low pressure contact rings146, thereby allowing bypass of the highly pressurized fluid around the face of the valve seat126. In the event pressurized fluid bypasses the rear face contact zone144and pressurizes the seat pocket116, the valve seat126is designed to flex away from the seat pocket116at the outer face contact zone142to provide a secondary path of bypass for the highly pressurized fluid. These features are specific to the valve seat126in the upstream valve seat pocket116.

Turning toFIGS. 10 and 11, shown therein are view of the valve seat126in the downstream valve seat pocket118when the ball valve100is in open and closed conditions, respectively. In the low-pressure condition depicted inFIG. 10, the low pressure contact rings146of the valve seat126are in contact with the valve ball124to prevent fluid flow around the valve ball124. The outer face contact zone142and rear face contact zone144support the valve seat against the downstream valve seat pocket118to prevent leakage around the rear face138and outer face136of the valve seat. The redundant dual-sealing is advantageous to the longevity of the ball valve100.

InFIG. 11, the ball valve100has been closed and the upstream pressure has forced the valve ball124to deflect downstream within the ball chamber120. In response to the increased force produced by the valve ball124, the valve seat126begins to compress into the downstream pocket118. As the low pressure contact rings146compress, the high pressure contact rings148contact the valve ball124to improve the seal between the valve ball124and valve seat126. The outer face contact zone142and the rear face contact zone144also enlarge as the valve seat126is pressed into the downstream pocket118. In the fully compressed state, the valve seat126provides four redundant seal rings at146and148on the front face134of valve seat126and two redundant seal zones at142and144on the downstream seat pocket118, thus substantially improving reliability.