Emergency Shutdown Valve Micro Stroke Testing
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Solution Overview
Problem
Current emergency shutdown valve testing methods, such as full and partial stroke tests, are impractical and costly, disrupt process operations, and can lead to false positives due to ridge formation on valve obturators, while lacking automation and compatibility with both pneumatic and hydraulic actuators.
Innovation Solution
A valve integrity manager system that automatically performs micro strokes of 20-25% closure, allowing for precise control and varying speeds to prevent ridge formation, and can be integrated with existing systems to reduce manpower costs and enhance reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If full stroke tests are performed to confirm ESD valve operability, then reliability of safety system is improved, but process flow interruption occurs making it impractical and economically undesirable
Solution Approach 1:
The patent applies partial action by performing micro strokes (1-5% closure) instead of full stroke tests. This partial movement is sufficient to confirm valve operability and detect potential issues while avoiding the harmful effect of complete process flow interruption. The micro stroke distance is carefully controlled to be just enough to verify valve functionality without causing production loss.
2Productivity
If partial stroke tests are performed to avoid complete process flow interruption, then productivity is improved, but significant impact on process variables occurs and manpower costs increase
Solution Approach 1:
The patent applies local quality by using different closure percentages for different testing needs. Micro strokes use 1-5% closure for routine monitoring with minimal process impact, while full stroke capability (100% closure) remains available when complete verification is needed. This localized approach to closure magnitude optimizes the balance between testing thoroughness and process continuity.
Solution Approach 2:
The patent implements automation that allows the system to self-monitor valve health without requiring operator presence or manual intervention during micro stroke tests. The automated control system performs the tests, monitors results, and detects anomalies independently, eliminating the manpower costs associated with traditional partial stroke tests while maintaining process flow continuity.
3Ease of operation
If repeated partial stroke tests are performed at the same closure percentage, then ease of operation is improved, but ridge formation on valve obturator occurs leading to false positives
Solution Approach 1:
The patent applies dynamics by varying the micro stroke closure percentage dynamically based on testing requirements and valve position. Rather than repeatedly testing at the same fixed closure point, the system adapts the stroke magnitude and position, preventing consistent contact at any single location on the obturator that would cause ridge formation. This dynamic approach maintains testing effectiveness while avoiding the reliability issue of false positives.
Data Source
AI summary
A valve integrity manager is coupled with a servo or stepper motor to direct micro stroke testing of emergency shutdown valves. During testing, the system orders a closure of 20-25% of an emergency shutdown valve, providing data that either confirms the operability of the valve or a deficiency, while minimizing any effect on process variables.