Safety Valve Partial Stroke Testing During Live Plant Operation
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Solution Overview
Problem
Current methods for verifying the operability of safety valves, such as partial stroke tests, have limitations including limited stroke distance and restricted starting conditions, which can lead to incomplete assessment of valve functionality and potential interference with plant operations.
Innovation Solution
A method involving a first and second partial stroke test, where the second test has a larger stroke range, determined by sensors monitoring the plant and process conditions, allowing for more comprehensive evaluation of valve operability without significantly disrupting ongoing operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a full stroke test is performed to verify complete valve operability, then the reliability of safety valve verification is improved, but plant operation is interrupted and costs increase
Solution Approach 1:
The patent applies partial stroke tests instead of full stroke tests, performing only a portion of the complete valve travel (e.g., 10-20% stroke) to verify valve operability. This partial action provides sufficient reliability for safety verification while avoiding the need to interrupt plant operation for complete valve cycling, thus resolving the contradiction between verification reliability and operational continuity
2Productivity
If a partial stroke test is performed during operation, then plant operation continuity is maintained, but the stroke distance is limited and assessment completeness deteriorates
Solution Approach 1:
The patent dynamically adjusts the stroke distance of partial stroke tests based on real-time valve position feedback and operational conditions. By making the test parameters adaptive rather than fixed, the system can perform more comprehensive assessments during operation without requiring full valve travel, thus improving assessment completeness while maintaining operational continuity
3Measurement precision
If multiple sensors are used to monitor plant conditions for determining test timing, then the precision of test execution timing is improved, but device complexity increases
Solution Approach 1:
The patent utilizes existing multi-functional sensors and control systems already present in modern valve actuation systems. These sensors serve multiple purposes including position monitoring, process condition detection, and test timing determination, thereby achieving precise test execution timing without significantly increasing overall system complexity
Data Source
AI summary
A method for verifying the operation of a safety valve having a valve member and a positioner for controlling the position of the valve member is proposed. The safety valve is part of a plant on which a process with a process medium runs. The plant has a sensor for monitoring the state of the plant, the process and the process medium. A sensor's measured value is used to determine a point in time during ongoing plant operation at which the operability of the valve can be verified in the context of a partial stroke test. The test can also be monitored with the sensor and the stroke range traversed therein can be dynamically adapted to the state. The test can thus be performed safely during operation and with an optimized stroke range. The method enables more frequent testing of and more reliable statements about the operability of the safety valve.