Sleeved Plug Valve Sealing Layout for Lower Operating Torque
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Solution Overview
Problem
Conventional sleeved plug valves require high input torque for rotation due to high compressive forces applied during assembly, which resist the rotation of the plug between open and closed states, necessitating a reduction in these forces while maintaining a fluid-tight seal.
Innovation Solution
The separation of static and dynamic seals allows for a reduction in compressive forces, with the static seal between the sleeve and housing and dynamic seal between the plug and sleeve being independent, reducing the torque required to rotate the plug by utilizing a modular valve body with a bimetallic construction and a polymeric sleeve with a low coefficient of friction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the plug and sleeve are both compressed downwardly into the internal chamber during assembly, then a fluid-tight seal is achieved, but high compressive forces are applied to the sleeve which resist plug rotation and require high input torque
Solution Approach 1:
The seal is divided into two separate components: an external seal between the sleeve outer surface and housing inner surface, and an internal seal between the plug outer surface and sleeve inner surface. This segmentation allows the external seal to provide the fluid-tight barrier while the internal seal accommodates plug rotation with minimal friction, resolving the contradiction between seal reliability and ease of operation.
Solution Approach 2:
The internal seal acts as an intermediary element between the plug and the external seal system. By providing a dedicated sealing interface that is separate from the external seal, it allows the plug to rotate within the sleeve without the high compressive forces that would otherwise be transmitted through the external seal to the housing, thereby reducing the input torque required for operation.
2Reliability
If high compressive forces are applied to the sleeve during assembly, then a fluid-tight seal is maintained, but the rotation of the plug between open and closed states is resisted
Solution Approach 1:
The sealing function is segmented into external and internal components. The external seal between the sleeve and housing maintains the fluid-tight barrier and withstands high compressive forces, while the internal seal between the plug and sleeve is designed to accommodate rotation with minimal resistance, thus separating the force-bearing function from the rotation function.
Solution Approach 2:
Different regions of the sealing system are given different properties: the external seal interface is designed for high compressive strength and fluid tightness, while the internal seal interface is designed for low friction and easy rotation. This local differentiation of sealing zone properties allows the system to simultaneously achieve reliable sealing and low operating torque.
3Ease of operation
If a polymeric sleeve with low coefficient of friction is used, then plug rotation is facilitated, but the compressive forces may compromise the fluid-tight seal
Solution Approach 1:
The sealing system is segmented into two independent sealing interfaces: the external seal between sleeve and housing that provides the fluid-tight barrier, and the internal seal between plug and sleeve that facilitates rotation. This segmentation allows the polymeric sleeve to have low friction for easy rotation while the external seal maintains the fluid-tight seal even under compressive forces.
Solution Approach 2:
The sleeve is constructed as a composite structure where the polymeric material provides low friction for rotation, while the external seal interface (which may include different materials or structural features) provides the fluid-tight sealing capability. This composite approach allows different regions of the sleeve to have different functional properties.
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 configuration reduces the input torque needed to rotate the plug by approximately 50% compared to conventional valves, while maintaining a fluid-tight seal and allowing for adjustable sealing to accommodate wear and tear without disassembly.
Implementation Method 1
a polymeric sleeve with a low coefficient of friction
Data Source
AI summary
A valve assembly includes a plug extending along a central axis and including a plug body having an external plug surface. The external plug surface tapers radially outwardly in a first direction along the central axis. The valve assembly further includes a sleeve having an internal sleeve surface defining an interior cavity. The internal sleeve surface tapers radially outwardly in the first direction. The plug body is positioned within the interior cavity of the sleeve. The plug is rotatable about the central axis relative to the sleeve, and the plug is also translatable along the central axis relative to the sleeve.