Cryogenic Ball Valve Seat Insert Assembly for Leak Prevention
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Solution Overview
Problem
Ball valves experience leakage due to deformation or shrinkage under extreme cryogenic conditions, which is not adequately addressed by existing technologies.
Innovation Solution
The implementation of an annular seat insert assembly comprising a seat insert with sealing lips and a support ring that biases the sealing lips against the seat insert cavity, forming multiple sealing interfaces to prevent leakage paths, using materials like PTFE and metallic alloys with coatings for enhanced durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional seat insert is used in a cryogenic ball valve, then the valve structure remains simple, but leakage occurs due to shrinkage and deformation at extreme temperatures
Solution Approach 1:
The seat insert is divided into multiple functional segments: an outer seat insert portion providing structural support, an inner seat insert portion with sealing lips for primary sealing, and a support ring for secondary sealing. This segmentation allows each component to address specific sealing challenges at different locations, preventing leakage paths while maintaining overall structural integrity under cryogenic conditions
Solution Approach 2:
A support ring is introduced as an intermediary component between the inner seat insert portion and the seat insert cavity. This support ring provides additional sealing functionality and structural reinforcement at the interface, preventing leakage through the support ring cavity while distributing mechanical stresses uniformly across the sealing surfaces
2Reliability
If the seat insert is made from a single material, then manufacturing is simple, but the material cannot adequately resist both thermal shrinkage and mechanical deformation at cryogenic temperatures
Solution Approach 1:
The seat insert employs composite material construction with the outer portion made from a thermoplastic material providing thermal stability and shrinkage resistance, while the inner sealing portion utilizes PTFE or PCTFE materials offering superior low-temperature flexibility and sealing properties. This composite approach allows each material to be optimized for its specific functional requirements, resisting both thermal shrinkage and mechanical deformation without compromising manufacturability
Solution Approach 2:
The invention utilizes materials with specifically selected glass transition temperatures (Tg) that remain below cryogenic operating temperatures. The outer seat insert material has a Tg at least 50°C below the minimum operating temperature, while the inner sealing material has a Tg at least 75°C below, ensuring both materials remain in a rubbery, flexible state and resist brittle deformation at extreme cold temperatures
3Reliability
If sealing lips are not biased against the seat insert cavity, then the structure is simpler, but leakage paths form under cryogenic conditions due to material shrinkage
Solution Approach 1:
The support ring is pre-configured with a biasing mechanism that applies continuous sealing force to the inner seat insert portion and sealing lips before fluid pressure acts on the system. This preliminary action ensures the sealing surfaces remain in firm contact despite thermal shrinkage, preventing leakage paths from forming in the first place under cryogenic conditions
Solution Approach 2:
The support ring provides localized reinforcement and sealing at the critical interface between the inner seat insert portion and the seat insert cavity. By concentrating sealing functionality at this specific location where leakage is most likely to occur, the design prevents secondary leakage paths without requiring complex sealing mechanisms throughout the entire seat insert structure
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 effectively prevents leakage through both primary and secondary paths, ensuring reliable fluid control under cryogenic conditions by maintaining robust sealing even at extreme temperatures.
Implementation Method 1
a support ring engaged with the at least one sealing lip and configured to bias the at least one sealing lip against a portion of a seat insert cavity
Implementation Method 2
when a ball valve is subjected to extreme environmental conditions such as cryogenic temperatures, the seat insert and/or other portions of the ball valve may shrink, deform, or otherwise change
Data Source
AI summary
Systems and methods are disclosed that include providing a valve suitable for maintaining a seal and preventing fluid flow through the valve at cryogenic temperatures. The valve includes a valve body having a longitudinal axis along a flow path through the valve, a ball selectively rotatable within the valve body to selectively allow fluid flow through the valve, a seat insert cavity formed within the valve body, and a seat insert assembly at least partially disposed within the seat insert cavity. The seat insert assembly includes a seat insert comprising at least one sealing lip and a support ring engaged with the at least one sealing lip and configured to bias the at least one sealing lip against a portion of the seat insert cavity to prevent leakage through a second leakage path when the ball valve is selectively rotated to prevent fluid flow through the valve.