Deflectable Annular Seal for High-Temperature Valve Shut-Off
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Solution Overview
Problem
Control valves, particularly balanced control valves, face challenges in meeting high-temperature and tight shut-off requirements due to material limitations and friction issues, which complicates their design and operation, especially for Class V valves that need to prevent leaks under stringent conditions.
Innovation Solution
A seal element with an annular ring that deflects to reduce the pressure differential area, allowing for a tight seal without the need for pilot balancing mechanisms, by engaging and disengaging effectively with the cage element, thus minimizing the force required for operation and eliminating the need for complex venting systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If seals made of graphite and metal are used to withstand high temperatures, then temperature resistance is improved, but friction increases which compromises control performance
Solution Approach 1:
The seal element is divided into multiple sealing surfaces (first sealing surface on the cage, second sealing surface on the plug, and third sealing surface on the plug peripheral edge). This segmentation allows different portions of the seal to perform different functions: the main sealing surfaces handle the sealing requirement while the reduced pressure differential area minimizes friction-related control issues
Solution Approach 2:
The seal element is designed with non-uniform pressure distribution characteristics. The close proximity of sealing surfaces creates localized high-pressure sealing zones while the overall reduced pressure differential area minimizes total friction. This local quality optimization allows graphite/metal materials to provide both high-temperature resistance and adequate control performance
2Reliability
If TEFLON seals are used to provide excellent shut-off, then shut-off quality is improved, but high-temperature suitability deteriorates
Solution Approach 1:
The seal element employs composite construction combining graphite and metal materials. Graphite provides excellent sealing properties similar to TEFLON, while the metal reinforcement enables high-temperature resistance. The composite structure achieves both tight shut-off (Class V standards) and high-temperature suitability that neither material could achieve alone
3Force
If the seal element engages and disengages the cage element effectively, then seating force is reduced, but the complexity of the seal mechanism increases
Solution Approach 1:
The seal element is designed as a deflectable annular ring rather than a rigid component. This dynamic structure allows the seal to automatically adjust its position and contact pressure in response to pressure differential changes. The deflection capability enables effective engagement and disengagement with the cage element, reducing seating force while maintaining simplicity in the overall mechanism
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
The solution enables valves to meet Class V standards by reducing the seating force needed for tight shut-off, simplifying the design, and eliminating the need for pilot balancing mechanisms, thereby enhancing operational efficiency and reducing costs.
Implementation Method 1
The annular ring can deflect in response movement of one part of the plug element relative to another part of the plug element
Data Source
AI summary
Embodiments of a seal element for use in a trim assembly that allow valves and, in particular, balance control valves to meet high-temperature and shut-off requirements. These embodiments can engage and disengage a cage element and a plug element of the trim assembly, thereby creating a seal that prevents leaks of working fluid that can compromise operation of the valve. In one embodiment, the seal element comprises an annular ring that circumscribes the outer periphery of the plug element. The annular ring can deflect in response movement of one part of the plug element relative to another part of the plug element. This deflection can cause the seal element to contact the cage element and the plug element in seal regions that are proximate to one another, and to the outer periphery of the plug element.