Partial Stroke Testing for Emergency Shut-Down Valves
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Solution Overview
Problem
Emergency shut-down valves in processing industries often fail to operate correctly due to seizing or slow response, posing hazardous situations, as they remain in operational positions for extended periods without proper testing, and existing automated testing methods rely on initial data or prolonged sequences that may disturb the controlled process.
Innovation Solution
A method for partial stroke testing of emergency valves involves initiating partial movement, measuring fluid parameters like pressure or energy, and reversing the stroke when a threshold is reached, comparing these measurements to a mathematical model to determine operational status without relying on prior tests or data, and performing iterative tests with varying threshold values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If full stroke testing is performed to ensure valve operational reliability, then valve reliability is improved, but process disturbance increases
Solution Approach 1:
The patent applies partial stroke testing where the valve is actuated only partially through its full range of motion. The testing mechanism initiates valve movement and monitors parameters such as current draw, position, and timing to detect potential failures without completing the full stroke. This partial action approach maintains valve reliability by exercising the actuator and detection mechanisms while avoiding full process disturbance that would occur with complete valve operation.
2Measurement precision
If prolonged testing sequences are used to detect valve seizing, then detection accuracy is improved, but productivity decreases
Solution Approach 1:
The patent employs feedback mechanisms that monitor multiple parameters during the valve testing process, including current draw, valve position, and timing characteristics. The system continuously compares measured values against expected ranges and can terminate the test early when sufficient data has been collected to make a reliable determination of valve status. This feedback-driven approach maintains high detection accuracy while minimizing testing duration and maximizing productivity.
Solution Approach 2:
The testing sequence is designed to be dynamic rather than static, adjusting the duration and intensity of testing based on real-time parameter measurements. The system can adaptively extend or terminate testing based on detected anomalies or confirmation of normal operation, optimizing the balance between detection accuracy and testing efficiency.
3Measurement precision
If iterative partial stroke testing with varying thresholds is performed, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent utilizes parameter changes in the testing approach by varying threshold values across multiple iterative tests. Different threshold criteria are applied in successive testing cycles to progressively refine the determination of valve operational status. This method improves measurement precision by examining valve behavior under multiple threshold conditions without requiring fundamentally more complex hardware, relying instead on sophisticated control logic and parameter analysis.
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
This approach allows for the detection of potential valve failures with minimal disturbance to the process, ensuring the valves are operational without the need for initial testing data, thereby enhancing safety and reliability by maintaining the valves in a ready state without full operation.
Implementation Method 1
measuring a pressure acting on the apparatus during a partial stroke test
Data Source
AI summary
A method for partially stroking an emergency valve apparatus is provided. The emergency valve apparatus comprises an actuator (103) and a valve member (101). The apparatus is movable between a first position and a second position. The method comprises the step of initiating a partial stroke movement of the apparatus from the first position towards the second position. A parameter of the fluid acting on the apparatus is measured. Once the measured parameter reaches a threshold value, the partial stroke movement is reversed.