Partial Valve Stroke Testing (PVST) is a diagnostic procedure used to evaluate the performance and condition of control valves by testing their response to partial opening or closing movements. Instead of fully opening or closing the valve, PVST involves actuating the valve to a predetermined intermediate position, typically between 20% to 80% of its full stroke range. This allows operators to assess the valve's dynamic response, seating integrity, and overall functionality without disrupting the process flow or shutting down the system entirely. Here are some key aspects of Partial Valve Stroke Testing:

1. Purpose:

   • The primary purpose of PVST is to verify the proper operation and functional integrity of control valves without performing a full stroke test, which can be time-consuming and disruptive to process operations.
   • PVST helps identify potential issues such as sticking, binding, excessive friction, uneven seating, or inadequate response time in control valves.

2. Procedure:

   • During PVST, the control valve is actuated to a predetermined partial stroke position, typically selected based on industry standards, manufacturer recommendations, or specific process requirements.
   • The valve position is monitored and recorded using positioners, limit switches, or other valve position sensing devices.
   • The valve's response time, travel characteristics, and dynamic behavior are evaluated to determine if they meet performance specifications and control requirements.

3. Benefits:

   • PVST allows operators to assess control valve performance while the process is in operation, minimizing downtime and production losses associated with full stroke testing.
   • It provides valuable diagnostic information on valve condition, response time, and seating integrity without disrupting process flow or system stability.
   • PVST helps identify potential issues early, allowing for timely maintenance or corrective actions to prevent valve failures, process upsets, or safety hazards.

4. Considerations:

   • When performing PVST, operators should ensure that the valve is actuated within a safe operating range to avoid overloading the actuator, causing damage to the valve or compromising system safety.
   • It is essential to follow proper procedures and safety protocols when conducting PVST to minimize risks to personnel, equipment, and the environment.

5. Integration with Asset Management Systems:

   • PVST data can be integrated into asset management systems or predictive maintenance programs to track valve performance trends, schedule maintenance activities, and optimize reliability and uptime.
   • By routinely performing PVST and analyzing the results, operators can proactively identify potential issues, prioritize maintenance activities, and extend the service life of control valves.

Overall, Partial Valve Stroke Testing is a valuable diagnostic tool for assessing control valve performance, identifying potential issues, and ensuring the reliability and integrity of process control systems while minimizing disruptions to operations.