Static Pressure Life Testing for High-Pressure Control Valve

High-pressure control valves must maintain durability, sealing, and operational performance over long periods of operation. To verify their reliability under actual working conditions, a static pressure life test is essential. This test simulates the opening and closing cycles of the valve in its working environment to assess its ability to operate effectively over time. To ensure accurate test results, careful preparation and strict adherence to operational procedures are required. Below are the specific preparations and operational guidelines for conducting static pressure life tests on high-pressure control valves.

Selection and Requirements for Testing Medium

The choice of testing medium is crucial in static pressure life testing. Typically, the medium is water at room temperature, but in some cases, air can be used. When using air, special care should be taken as follows.

1. Testing Medium

Room temperature water is the most common choice because it effectively simulates the valve's operation with liquid media and is easy to handle. When air is used as the test medium, the opening pressure differential must be controlled according to the valve's rated differential pressure to ensure proper opening and closing throughout the test. This prevents errors caused by differences in the properties of the media.

2. Pressure Control

The pressure of the medium during the test should be controlled in accordance with the valve's design specifications. For high-pressure control valves, the pressure must align with the rated operating pressure range to ensure the test conditions reflect actual working conditions.

Requirements for Operating Equipment Coordination

The coordination of operating equipment is vital during the static pressure life test. Regardless of the valve's operating method, the associated operating equipment must participate in the opening and closing cycle of the test. Specific requirements are as follows.

1. Manual Operating Devices

For valves manually driven by handwheels or via worm gear reduction mechanisms, the manual valve should be operated using the life test machine's driving mechanism. This ensures synchronized operation of the handwheel and valve.

2. Electric, Hydraulic, Pneumatic Operating Devices

For valves driven by electric, hydraulic, pneumatic, or other electro-hydraulic-pneumatic devices, the test should use a matching actuator to simulate the real operating conditions, ensuring a comprehensive performance evaluation.

Operational Process of Static Pressure Life Testing

During static pressure life testing, the valve's opening and closing processes must follow a strict procedure to ensure the authenticity and accuracy of the test. The specific operational steps are as follows.

Execution of Opening and Closing Cycles: The test should begin with the valve fully closed, gradually opening to over 90% of the actual opening. The key points of the opening and closing process are:
Opening: The valve should gradually open, with the medium filling the valve cavity under pressure.
Closing: During the closing process, the medium pressure should remain between 90% and 100% of the valve's nominal pressure. After closure, the outlet side of the valve should release the medium pressure.
Pressure Differential Control: During the test, the valve should operate under the medium's pressure differential. If the valve has a specific rated pressure differential, the test should be conducted based on this differential to ensure the test conditions match the actual operating environment.

Control of Operating Torque

Operating torque is a critical parameter in static pressure life testing. Excessive torque can reduce the valve's lifespan. The operating torque should be controlled according to the valve's sealing method and the type of actuator. The specific requirements are as follows.

1. Non-Flat Sealing Valves

For valves other than flat-seal plate gate valves, the operating torque during the test should be based on the maximum opening and closing torque, measured manually. The torque should not exceed the maximum specified by the valve's handwheel or the product standards.

2. Flat-Seal Plate Gate Valves

For flat-seal plate gate valves, the operating torque should be based on the torque required for opening under pressure, ensuring effective sealing. The deviation of the driving mechanism's operating torque should be within ±5% to ensure consistent torque during the opening and closing processes.

Sealing Performance and Operating Torque Checks

During the static pressure life test, regular checks must be performed to ensure the valve's sealing and operational performance. Every 200 to 300 opening and closing cycles, the sealing and operating torque should be checked. The specific steps are as follows.

1. Sealing Performance Check

After a few opening and closing cycles, check the sealing performance to ensure that the valve maintains a good seal throughout the test. If the sealing is satisfactory, continue the test.

2. Operating Torque Check

For manually operated valves, if the operating torque changes, adjustments may be made. However, for electric, hydraulic, or pneumatic-driven valves, the operating torque should not be adjusted. The operating torque should remain within an acceptable range to ensure smooth operation of the valve.

Installation and Flow Direction Requirements

During the test, if the high-pressure control valve has specific installation and flow direction requirements, it must be installed according to the valve's installation instructions and flow direction markings. Incorrect installation can lead to distorted test data and affect the reliability of the results.

Recording and Controlling the Number of Test Cycles

The number of opening and closing cycles must be accurately recorded during the static pressure life test. This is typically done through the life test machine or by using a signal from a stroke switch driven by electric, hydraulic, pneumatic, or other linked devices, combined with an electromagnetic counter to track the cycle count in real-time. This ensures the accuracy of the test cycle count and minimizes human error.

Conclusion

The static pressure life test of high-pressure control valves is a critical procedure for verifying the valve's durability, sealing, and reliability. Through careful preparation and adherence to operational procedures, the effectiveness of the test and the long-term stability of the valve can be ensured. Strict compliance with the operational requirements, regular checks on sealing performance and operating torque, and accurate recording of test cycles all contribute to the precision of the test results and the valve's extended service life.