Valve Safety Margin Determination System
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Solution Overview
Problem
Existing emergency shutdown systems for valves in industries like oil, gas, and power face challenges such as valve sticking due to infrequent use, leading to safety concerns and false failures during partial stroke testing, which disrupt processes and require extensive maintenance.
Innovation Solution
A system that determines the safety margin of installed actuators by measuring actual valve torque or thrust requirements, allowing for visual, audible, or electronic observation of the safety margin, thereby preventing spurious valve travel and false failures, and enabling safe and efficient partial stroke testing without process disruption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If full stroking or completely closing the valve is performed for testing, then valve functionality is confirmed, but process disruption occurs
Solution Approach 1:
The patent implements partial stroke testing where the valve is moved only a portion of the full stroke distance (e.g., 10-50% of full travel) rather than completing the entire stroke. This partial action is sufficient to detect sticking conditions and confirm valve functionality while avoiding the process disruption that would result from full valve closure.
2Ease of operation
If mechanical hard stop devices are used for partial stroke testing, then valve motion is constrained to prevent over travel, but operator training and procedures become complex
Solution Approach 1:
The patent replaces mechanical hard stop devices with an electronic control system that uses a sensor to detect valve position and a controller to automatically stop the actuator at the predetermined partial stroke position. This substitution eliminates the need for manual engagement of mechanical stops and reduces operator training requirements while maintaining precise control over valve travel.
3Ease of operation
If air pressure is carefully released to achieve partial stroke position, then valve motion is controlled, but available torque becomes insufficient
Solution Approach 1:
The patent employs a dynamic control approach where the actuator operates in two distinct phases: first, it applies full torque to overcome static friction and initiate valve motion from the closed position; second, once motion begins, it reduces torque to maintain controlled movement to the partial stroke position. This dynamic torque adjustment ensures sufficient force for valve activation while preventing excessive travel.
4Reliability
If pressure and time limits are programmed to prevent spurious motion, then false failures are reduced, but maintenance requirements increase
Solution Approach 1:
The patent incorporates a sensor that provides real-time feedback on valve position during the testing process. The controller monitors this feedback and automatically compares the actual valve travel against the predetermined partial stroke threshold. This feedback mechanism enables automatic detection of sticking conditions without requiring manual interpretation of pressure or time parameters, thereby reducing false failures and minimizing maintenance intervention requirements.
Data Source
AI summary
A system for determining the operability of a valve in active service which provides a user with real time information pertaining to the Safety Margin, the valve torque or thrust, and the percentage of valve MAST that is required for operation. The system employs a combination of an actuator package comprised of a primary actuator, a tandem force module, and a controller operatively connected to the output shaft of the primary actuator, the controller including a processor for calculating the above-described values and providing an output which can be visually, audibly, or electronically observed.