Control Valve Partial Stroke Testing With Minimal Flow Disruption
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Solution Overview
Problem
Control valves in industrial processes face challenges in accurate testing due to potential disruptions in flow when testing induces movement, making it difficult to diagnose issues like obstructions or component failures without affecting the process.
Innovation Solution
A controller system that performs in-situ testing using partial stroke testing (PST) with a test shape that minimizes impact on process parameters, allowing for the diagnosis of valve assembly issues such as sticking, jams, or broken components with minimal disruption to the process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If control valves are tested in the field by inducing movement, then diagnostic data can be obtained to detect potential failures, but flow through the device is adversely affected and the process is disrupted
Solution Approach 1:
The patent applies partial stroke testing (PST) where the valve is moved only a fraction of its full travel distance (e.g., 10-20% of full stroke) rather than completing a full opening/closing cycle. This partial movement is sufficient to detect sticking, binding, or mechanical issues while minimizing the impact on process flow and avoiding complete process disruption that would occur with full-stroke testing.
Solution Approach 2:
The patent modifies the testing parameters by using small, controlled valve movements instead of full-stroke movements. By changing the magnitude and duration of valve actuation, the system achieves diagnostic objectives while keeping flow disruption within acceptable limits. The test parameters (stroke distance, speed, duration) are optimized to balance diagnostic effectiveness with process continuity.
2Reliability
If full stroke testing is performed to thoroughly diagnose valve issues, then comprehensive diagnostic data is obtained, but significant process disruption and downtime occur
Solution Approach 1:
The patent uses partial stroke testing to achieve sufficient diagnostic information without requiring complete valve movement. By testing at reduced stroke distances, the system identifies mechanical issues, sticking, or binding problems while maintaining process operation, thereby eliminating the downtime that would result from full stroke testing or complete valve shutdowns.
Solution Approach 2:
The patent enables continuous or near-continuous process operation during valve diagnostics by performing tests that do not require stopping the process. The partial stroke movements are integrated into the operating valve's normal function, allowing diagnostics to occur while the valve remains in service, thus eliminating downtime entirely.
3Reliability
If valve components are exercised frequently to prevent sticking, then component reliability is improved, but process parameters are adversely affected
Solution Approach 1:
The patent implements frequent partial stroke exercises (e.g., moving the valve 10-20% of full stroke) to prevent component sticking and binding. These small movements are sufficient to maintain mechanical operability of valve components while causing minimal disturbance to process parameters such as flow rate, pressure, or temperature, thus avoiding the harmful effects of more aggressive exercising.
Solution Approach 2:
The patent optimizes the exercise parameters (movement amplitude, frequency, duration) to achieve the minimum necessary valve actuation for preventing sticking. By carefully controlling these parameters, the system maintains component reliability while keeping deviations in process parameters within acceptable limits, thus minimizing harmful effects on the process.
Data Source
AI summary
A controller is configured to perform in-situ testing on a control valve. These configurations can generate a signal that changes position of a closure member in the valve during operation of a process. These changes exercise components of the valve for a short period of time. This testing may result in data that can indicate whether the device is operating properly or may be in need of maintenance or repair.