Pressure Relief Device for Double Isolation Valve Overpressure
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Solution Overview
Problem
Double isolation valves, when exposed to thermal sources, experience unacceptable pressure increases due to retained overpressure in the valve body cavity, and existing pressure relief devices struggle to effectively direct excess pressure to the high-pressure side without compromising sealing or bi-directional functionality.
Innovation Solution
A pressure relief device with piston-effect seats that retract under reverse pressure, directing overpressure back to the high-pressure side through metal-to-metal contact and spring-actuated mechanisms, maintaining the valve's sealing and bi-directional capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If double barrier isolation valves use tight seal seats designed to prevent fluid leakage in both directions, then sealing performance is improved, but body cavity overpressure cannot be relieved when exposed to thermal sources
Solution Approach 1:
The seat design transitions from static tight sealing to dynamic conditional sealing. The seat remains engaged under normal bidirectional pressure to maintain sealing, but is designed to disengage when reverse pressure exceeds a threshold, allowing overpressure relief while maintaining reliability under normal operating conditions
Solution Approach 2:
The pressure relief mechanism changes the pressure parameter distribution by creating a controlled pressure differential across the seat. When body cavity pressure exceeds the sum of downstream pressure and spring force, the seat lifts, changing the pressure state from confined to relieved, thus resolving the overpressure issue while preserving sealing during normal operation
2Object-affected harmful factors
If a pressure relief device is added to relieve body cavity overpressure, then overpressure relief is improved, but the device must discern which side is high pressure to direct relief correctly
Solution Approach 1:
The pressure relief device requires no external control system or sensors to detect high pressure side. The mechanism automatically responds to pressure differentials through its mechanical design, where the seat naturally lifts when reverse pressure exceeds the spring force threshold, eliminating the need for complex detection systems
Solution Approach 2:
The spring acts as an intermediary element between the bidirectional pressure forces and the seat. It provides a predetermined force that balances normal operating pressures while allowing the seat to lift when excessive reverse pressure occurs, simplifying the pressure management mechanism without requiring active detection
3Object-affected harmful factors
If the pressure relief device allows seat retraction for pressure relief, then overpressure relief is improved, but sealing capability may be compromised
Solution Approach 1:
The spring is pre-loaded to exert a force that maintains seat engagement under normal bidirectional pressure conditions. This preliminary counteracting force ensures sealing capability is preserved during normal operation, while allowing controlled disengagement only when reverse pressure exceeds the spring force threshold
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
Effectively relieves valve body cavity overpressure by directing it to the high-pressure side, maintaining acceptable pressure levels without impacting sealing or bi-directional performance, ensuring the low-pressure side remains isolated.
Implementation Method 1
The disc is interposed between two floating seats and is actuated by a spring positioned centrally between the two seats so as to maintain the disc in a central position between the two seats.
Implementation Method 2
If the pressure in the valve body cavity exceeds the sum of the downstream pressure and the force exerted by the spring, the disc will be pushed laterally to open the valve
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3
AI summary
A pressure relief device for a double isolation valve comprises a body (102) with a valve cavity. The valve body has a pocket formed therein. A disc (104) is disposed in the central section of the pocket. The disc is interposed between two spring - actuated seats (108a, 108b). Each of the seats is in fluid communication with opposing valve sides. The pocket central section is in fluid communication with the valve body cavity. Each of the seats is provided with two different types of gaskets in series. In operation, reverse pressure causes retraction of the seats, thereby relieving valve body cavity overpressure.