Ball Valve Seal Assembly for Bidirectional Cryogenic Sealing
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Solution Overview
Problem
Ball valves face challenges in maintaining effective seat seal performance, particularly in extreme environmental conditions like cryogenic temperatures, where existing seals fail to provide reliable bidirectional sealing.
Innovation Solution
A double piston effect seal design for ball valves, featuring a resilient ring with polymer rings and engagement features, including notches, ridges, and energizing elements, that form a symmetrical and rotatable structure to ensure secure sealing at both upstream and downstream positions, even at cryogenic temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional seat seals are used in ball valves, then the structure is simple and easy to manufacture, but the sealing reliability deteriorates in cryogenic temperatures below -150°C
Solution Approach 1:
The seal is divided into multiple functional segments: a resilient ring providing elastic recovery, polymer rings providing chemical resistance and sealing, and energizing elements providing bidirectional sealing force. Each segment performs a specific function, and their combination achieves reliable cryogenic sealing without requiring a completely new design.
Solution Approach 2:
The seal assembly uses composite materials combining resilient rubber or elastomer with fluoropolymer or PTFE. This composite structure leverages the elastic properties of the resilient material and the chemical resistance and low-temperature performance of the polymer materials, achieving reliable sealing in cryogenic conditions.
2Adaptability or versatility
If single piston effect seat seals are used, then the structure is simpler, but the sealing capability is limited to unidirectional operation only
Solution Approach 1:
The engagement features include asymmetric notches and ridges that create different sealing surfaces for upstream and downstream directions. The resilient ring is positioned to provide differential energizing force, enabling the seal to adapt to pressure differential in both directions while maintaining a relatively simple overall structure.
Solution Approach 2:
The resilient ring provides dynamic adaptability by deforming in response to pressure differentials from either direction. This dynamic response allows the seal to automatically adjust its sealing force based on the direction of pressure, achieving bidirectional sealing without requiring two separate seal assemblies.
3Reliability
If existing seals are used in extreme environmental conditions, then the design is straightforward, but the seal performance deteriorates at cryogenic temperatures
Solution Approach 1:
The seal design changes the material parameters by selecting resilient rings made from cryogenic-grade elastomers and polymers that maintain their elastic properties at low temperatures. The polymer rings are selected for their low-temperature ductility and resistance to embrittlement, ensuring sealing performance below -150°C.
Solution Approach 2:
The resilient ring acts as a cushioning element that anticipates and compensates for thermal contraction and material stiffening that occur at cryogenic temperatures. By providing continuous elastic force, it maintains sealing pressure despite the harsh thermal environment.
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 provides enhanced sealing capabilities in cryogenic conditions, ensuring reliable bidirectional sealing and improved performance in extreme temperatures, thereby addressing the limitations of existing seat seal technologies.
Implementation Method 1
a resilient ring defining an engagement feature and a first polymer ring disposed adjacent to a first axial end of the resilient ring
Implementation Method 2
double piston effect seals operate bidirectionally
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
A seal for a ball valve comprising a resilient ring defining an engagement feature; a first polymer ring disposed adjacent to a first axial end of the resilient ring and coupled with the engagement feature; and a second polymer ring disposed adjacent to a second axial end of the resilient ring and coupled with the engagement feature.