Contoured Ball Valve Seat Geometry for Sealing Wear Reduction
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Solution Overview
Problem
Traditional ball valves face challenges in maintaining effective sealing and reducing wear and tear due to uneven fluid pressure distribution across their sealing surfaces, which can lead to increased contact stress and potential galling, especially under high-pressure conditions.
Innovation Solution
The ball valve design incorporates toroidal convex and spherical concave sealing surfaces for the seats and counterseats, allowing for differential piston effects that enhance sealing pressure and reduce contact area, along with a cap mechanism for mechanical retraction of the seats during valve opening to mitigate stress and wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If traditional flat sealing surfaces are used in ball valves, then the structure is simple, but uneven fluid pressure distribution causes increased contact stress and potential galling
Solution Approach 1:
The patent applies curvature to the sealing surfaces by providing a convex arc-shaped sealing surface on the ball and a corresponding concave arc-shaped sealing surface on the seat. This curved geometry allows the sealing surfaces to conform to each other under pressure, distributing fluid pressure more evenly across the contact area and preventing localized stress concentrations that lead to galling, while maintaining manufacturing feasibility through standard machining processes.
2Reliability
If high sealing pressure is applied to ensure sealing, then sealing efficiency improves, but wear and tear on components increases
Solution Approach 1:
The arc-shaped sealing surfaces create a line contact or small area contact geometry that concentrates sealing force effectively while distributing it along the curved path. This reduces the contact stress at any single point compared to flat surfaces, thereby maintaining sealing efficiency while reducing overall wear and extending component service life.
Solution Approach 2:
The patent changes the geometric parameters of the sealing surfaces from flat to curved, specifically defining the convex arc on the ball with a specific radius of curvature and the corresponding concave arc on the seat. This parameter change optimizes the pressure distribution characteristics, achieving effective sealing at lower contact stresses and reduced wear rates.
3Device complexity
If seats are held stationary against the ball, then the sealing mechanism is simple, but contact stress and wear increase under high-pressure conditions
Solution Approach 1:
The curved sealing surfaces enable the ball to naturally press against the seat with optimized contact geometry during operation. The arc shapes allow for better conformity and pressure distribution, reducing contact stress and wear without requiring complex active control mechanisms, thus maintaining sealing mechanism simplicity while improving durability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design improves sealing efficiency, reduces wear on components, decreases run torque, and increases valve cycle life by maintaining a consistent and predictable sealing contact, even under varying pressure conditions.
Implementation Method 1
allowing for differential piston effects that enhance sealing pressure and reduce contact area
Implementation Method 2
The contour of the bore is shaped such that, in operation, the contour of the bore creates a low-pressure region within the fluid stream that draws particles away from the sealing surface
Data Source
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AI summary
Valves having seats and counterseats with various contours are provided. In one embodiment, a valve includes a body and a flow control assembly inside the body. The flow control assembly includes a ball, a seat installed on the ball, and a counterseat. The ball is rotatable between open and closed positions to control flow through the body and the seat and counterseat include mating surfaces that engage when the ball is in the closed position such that the seat seals against the counterseat along the mating surfaces. Further, the mating surface of the counterseat can be a concave surface, the mating surface of the seat can be a convex surface, and at least one of the mating surfaces can have a toroidal contour.