Solenoid Valve Pressure-Drop Testing Without Safety Valve Movement
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Solution Overview
Problem
Existing methods for testing the operability of solenoid valves used to trigger safety valves cannot determine their functionality without moving the valve member, which is necessary for ensuring the safety and reliability of the safety valve system.
Innovation Solution
A method that increases the pressure in the drive fluid above the operating pressure, then measures the pressure drop to determine if the solenoid valve correctly switches to the safety position without moving the valve member, using a predetermined pressure difference and time to assess the solenoid valve's operability without affecting the safety valve's position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the solenoid valve is tested by triggering the safety valve (changing valve member position), then the solenoid valve functionality can be verified, but the safety valve position changes which affects plant operation
Solution Approach 1:
The testing function is segmented from the actual safety valve operation. The method separates the solenoid valve testing from the safety valve actuation by using a virtual trip signal that simulates the trip condition without actually moving the valve member, allowing independent testing of the solenoid valve while maintaining plant operation
Solution Approach 2:
A positioner is introduced as an intermediary device between the solenoid valve and the safety valve. The positioner receives the trip signal from the solenoid valve and can simulate the trip condition for testing purposes without requiring the actual safety valve to move, thus mediating between the test requirement and operational continuity
2Ease of operation
If the solenoid valve is tested without changing the safety valve position, then plant operation is maintained, but the testing method becomes more complex requiring additional sensors and control logic
Solution Approach 1:
The mechanical testing method (actually moving the valve member) is replaced with an electronic/software-based approach. The system uses electronic sensors and control logic to detect and evaluate the solenoid valve's trip signal and the resulting positioner response, substituting mechanical actuation with electronic measurement and analysis
Solution Approach 2:
The actual trip condition is copied or simulated electronically rather than physically enacted. The system creates a virtual representation of the trip event by detecting the solenoid valve's electrical signal and the positioner's response, allowing testing without physical valve movement
3Reliability
If a partial stroke test is performed on the safety valve, then the valve member mobility is verified, but this does not check the solenoid valve triggering function
Solution Approach 1:
The system implements feedback by monitoring the positioner's response to the solenoid valve's trip signal. Sensors detect whether the positioner correctly interprets and responds to the trip command, providing feedback information about the solenoid valve's triggering function that is separate from the safety valve's mechanical mobility
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
Enables the independent testing of solenoid valve operability, ensuring it can reduce pressure in the actuator, thereby maintaining the safety valve's position and optimizing maintenance intervals by identifying potential issues in the pressure generation system.
Implementation Method 1
the solenoid valve vents the actuator when an emergency signal is received from the control and a dangerous condition is detected. For this purpose, the solenoid valve releases, for example, a connection between the actuator and the ambient air which reduces the pressure in the actuator
Implementation Method 2
The actuator comprises, for example, a piston or diaphragm arranged in a chamber and coupled to a spring. When the pressure in the chamber falls below the load of the spring, the spring causes the piston in the chamber to be actuated
Data Source
AI summary
The disclosure provides a method for testing a solenoid valve for triggering a safety valve having a single-acting fluidic drive and a positioner. The drive fluid pressure is increased by a first pressure difference. An attempt is made to switch the solenoid valve to the safety position. The drive fluid pressure is measured at a specified point in time that is selected such that the pressure in the drive fluid lowers at most by the first pressure difference. If the pressure in the drive fluid is higher than a reference pressure at the specified point in time, the functionality test of the solenoid valve is failed. The lowering of the pressure in the drive fluid is monitored over a defined period of time to make conclusions regarding the pressure generating system. The pressure does not fall below the operating pressure so the position of the valve member remains constant.