Valve Packing Assembly with Shape-Memory Member for Leakage Control
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Solution Overview
Problem
Valves experience fugitive emissions due to non-uniform compression and material consolidation of packing rings, leading to leakage, especially at elevated temperatures, which is a challenge for maintaining effective sealing performance under stringent health and environmental regulations.
Innovation Solution
A packing assembly utilizing shape-memory alloy segments with inclined surfaces and a thermal-responsive shape-memory member that expands and increases the packing assembly's height, evenly distributing compressive force across the packing rings, thereby compensating for force loss due to consolidation and temperature changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional packing rings are used without shape-memory members, then the device complexity is low, but the sealing performance deteriorates at elevated temperatures due to non-uniform compression and material consolidation
Solution Approach 1:
The shape-memory member changes its physical parameters (length, cross-sectional area) in response to temperature changes. When temperature increases, the member expands or contracts to automatically adjust the compressive force on packing rings, maintaining uniform pressure distribution and preventing leakage without requiring complex external control systems
Solution Approach 2:
The shape-memory member provides self-regulating sealing by automatically responding to temperature changes. The material consolidates or expands based on thermal conditions, continuously adjusting compressive force on the packing rings without external intervention, thereby maintaining reliable sealing performance in high-temperature applications
2Reliability
If packing rings are compressed to improve sealing, then sealing performance improves, but material consolidation occurs leading to force loss and leakage
Solution Approach 1:
The shape-memory member provides dynamic adjustment of compressive force based on real-time temperature conditions. As temperature changes during operation, the member automatically expands or contracts to maintain optimal compressive pressure on the packing rings, preventing force loss from consolidation and ensuring sustained sealing performance over time
Solution Approach 2:
The shape-memory member acts as a thermal feedback mechanism that senses temperature changes and automatically adjusts compressive force accordingly. When temperature increases causing material consolidation, the member responds by adjusting its dimensions to restore the original compressive pressure, creating a self-correcting system that maintains sealing integrity
3Force
If the packing assembly height is increased to compensate for consolidation, then compressive force is maintained, but the device complexity increases
Solution Approach 1:
The shape-memory member changes its dimensional parameters (length, cross-sectional area) in response to temperature to automatically compensate for packing ring consolidation. This provides a simple, elegant solution that maintains compressive force without requiring complex mechanical adjustment mechanisms or multiple components
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 reduces fugitive emissions by ensuring consistent and enhanced axial and radial compressive forces on the packing rings, improving sealing performance and reducing maintenance needs, particularly in high-temperature applications.
Implementation Method 1
A packing assembly utilizing shape-memory alloy segments with inclined surfaces and a thermal-responsive shape-memory member that expands and increases the packing assembly's height
Data Source
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AI summary
A packing assembly for a valve includes a first segment having at least one first guiding surface, and a second segment having at least one second guiding surface in engagement with at least a portion of the at least one first guiding surface. A shape-memory member couples the first and second segments. The shape-memory member may be formed of a material that is responsive to changes in temperature, so that, in response to a change in temperature, the shape-memory member may cause relative movement of the first and second segments in a first direction. In response to the movement, the first and second guiding surfaces may cause relative displacement of the first and second segments in a second direction.