How to do Safety valve testing and calibration?

Purpose and Scope:

This procedure provides a thorough explanation of how to calibrate and test a safety relief valve using standards.

Tools required for control valve calibration:

• Safety valve test bench
• Compressed nitrogen supply – N2 Cylinder
• Precision Standard air pressure regulator.
• Tubes and standard fittings 
• Reference standard pressure gauge 
• Standard tools
• Soft Cloth for cleaning.

Safety

• For information on fundamental safety, general principles, testing and calibration activities in process industries, please click the link provided below.
• Process Industries Calibration Process: Basic Safety and General Considerations
• Implement a proper LOTO procedure to isolate the equipment from any energy sources from the process. This involves shutting off the system power supply, relieving pressure, and securely locking and tagging the valves or switches to prevent accidental activation.
• Wear appropriate PPE such as safety glasses, gloves, hearing protection, and protective clothing to protect yourself from potential hazards, including flying debris, chemicals, or loud noises.
•  Ensure that the work area has proper ventilation to prevent the buildup of hazardous gasses, vapors, or fumes. If necessary, use local exhaust ventilation or respiratory protection to maintain air quality.
• Before working on the safety valve, inspect the test bench, tools, and equipment for any signs of damage or malfunction. Make sure the test bench is stable and secure to avoid accidents during testing.
• When installing or removing the safety valve, use suitable lifting techniques to avoid strain or damage. Use mechanical lifting devices or seek help if the valve is heavy or unusually shaped.
• Before removing the safety valve, ensure that the system is adequately depressurized and isolated to prevent sudden release of pressure, steam, or hazardous substances. Follow proper depressurization procedures as per industry guidelines.
• Have appropriate containment measures in place to catch any liquids or substances that may be released during the removal and testing process. Additionally, ensure proper drainage to prevent any spillage or accumulation.
• Refer to the manufacturer’s instructions and guidelines specific to the safety valve model being worked on. Adhere to their recommended safety precautions, testing procedures, and any specific requirements they outline.
• Dispose of any waste materials, such as old gaskets or seals, according to environmental regulations and company policies. Follow proper waste management procedures to prevent contamination or environmental harm.
• Ensure that personnel involved in the removal and testing of safety valves are properly trained, competent, and familiar with the safety protocols. Regularly update their training to stay informed about the latest safety practices.

Safety valve calibration and test Setup

• Ensure that the test bench is clean, stable, and in good working condition.
• Confirm that the clamping system is securely attached to the test bench and functioning properly.
• Check that the clamping mechanism is free from any debris, obstructions, or damage.
• Inspect the safety valve for any visible damage or defects. If any issues are found, consult the manufacturer before proceeding.
• Ensure that the valve is the correct model and size for the intended application.
• Verify that the valve is clean and free from any contaminants.
• Align the safety valve with the clamping system on the test bench.
• Carefully position the valve to ensure proper alignment with the inlet connections on the test bench.
• Align any bolt holes or mounting points on the valve with the corresponding features on the clamping system.
• Activate the clamping system to hold the safety valve securely in place.
• Follow the specific instructions provided by the test bench and clamping system manufacturer for proper clamping procedures.
• Apply the necessary clamping force evenly to avoid damaging the safety valve or the test bench.
• Review the test bench’s instrumentation, including pressure gauges and relief valve mechanisms, to ensure they are calibrated and in good working condition.

• To install a bubble counter on the outlet of a safety valve, insert a rubber plug with a fitting into the valve outlet. Attach a tube to the fitting, ensuring a secure connection. The other end of the tube is placed in the bubble counter to monitor gas flow visually.
• Ensure the test bench is compatible with nitrogen and suitable for high-pressure connections.

• Verify that the nitrogen cylinder is properly secured in an upright position.
• Inspect the cylinder and regulator for any damage or defects.
• Attach the regulator to the cylinder valve, ensuring a tight connection.
• Open the cylinder valve slowly and gradually to allow nitrogen to flow.
• Connect the regulator outlet to the test bench’s pressure inlet using suitable fittings or adapters.
• Adjust the regulator to set the desired pressure on the test bench recommendation.
• Monitor the pressure gauge on the test bench to ensure it remains within the desired range for testing.
• Close the cylinder valve after testing is complete.
• Properly secure and store the nitrogen cylinder according to safety guidelines and regulations.
• Inspect all associated piping and connections for leaks or damage before initiating any testing.
• Follow the specific test procedures outlined by the safety valve manufacturer or relevant industry standards and regulations.
• Gradually increase the pressure within the test bench, monitoring the safety valve’s response, lift pressure, and set pressure.
• Now the setup is ready for the calibration and testing

Safety valve calibration and testing procedure

Safety Valve Calibration and Adjustment with Bubble Counter inside Water

• Ensure all connections are secure and properly aligned.
• Fill a container with water and place a bubble counter inside the water.
• Connect the bubble counter to the outlet of the safety valve using suitable tubing or connectors.
• Ensure that the bubble counter is submerged in the water and positioned to capture the gas released from the safety valve.
• Gradually increase the pressure on the test bench using the nitrogen gas supply regulator and the controls on the test bench.
• Monitor the pressure readings on the standard pressure gauge and observe the bubble counter.
• Adjust the pressure until the desired calibration pressure is reached.
• Observe the bubble counter and note the number of bubbles passing through it per unit of time.

• Compare the observed bubble count to the safety valve manufacturer’s specifications or any applicable standards.
• If the bubble count is outside the acceptable range, make necessary adjustments to the safety valve, such as adjusting the spring tension provided for calibration and also replace the faulty component observed during calibration
• Repeat the calibration process if further adjustments are required, ensuring the safety valve meets the specified bubble count criteria with set pressure.
• Record the calibration pressure and any adjustments made during the process for future reference.

How do you test a pressure safety valve?

Safety Advice for the Popping Test

• When conducting safety valve  Pop-up testing, the following safety considerations need to be taken:
• Always stay within the test stand’s pressure limit.
• Popup testing should only be done by someone who has received all necessary training.
• Verify that the test stand is properly installed permanently.
• Always keep the operator away from the valve outlet.
• Shields and eye protection should be worn by everyone in the test area.

Pop-up Test Procedure with Safety Valve Test Bench

• Set up the safety valve test bench in a well-ventilated area, ensuring it is in proper working condition.
• Connect the safety valve to the appropriate location on the test bench.
• Ensure all connections are secure and properly aligned.
• Connect a standard pressure gauge to the test bench using suitable fittings and connectors.
• Remove the bubble counter setup such as rubber plug and tube fitting from the safety valve outlet.
• Connect the nitrogen gas supply to the test bench.
• Gradually increase the pressure on the test bench using the controls, while monitoring the pressure readings on the standard pressure gauge.
• Continue increasing the pressure until the safety valve pops open.
• Note the pressure at which the safety valve opens. This is the set pressure.
• Release the pressure and ensure that the safety valve properly reseats.
• Verify that the safety valve reseats securely and there is no residual leakage.
• Record the set pressure and any necessary adjustments or deviations observed during the pop-up test.

Recording calibration and testing 

• You must repeat the calibration procedure for the safety valve several times as required until it is calibrated and pop-up tested to the required tolerance.
• If the safety valve set value does not fall within an acceptable range and have deviated from the permitted range, a safety valve has to be serviced or replaced.
• No extra calibration of safety valve is required if every output value (+/-%) falls within accepted limits.

Completion of calibration

• When the calibration and testing of safety valve has been successfully completed, attach the calibration label to the safety valve with set and reset pressure value.
• When the calibration of safety valve is complete, clean, store it somewhere safe, and record the calibration and pop up test result information for future use.
• Disconnect the regulators, pressure gauge, and other equipment from the safety valve test bench.
• Reinstall the safety valve in the processing area.
• Make sure the safety valve installed back workplace is tidy.
• De-isolate the equipment.
• Put the safety valve back into use and do the over pressure test to check that it is operating normally once you have done so.

Sample calibration report

The following picture displays how the safety valve calibration sample report was completed with safety valve test bench using a pressure regulator and a standard pressure gauge as the reference.

The Excel template that was used to make the safety valve calibration and testing report can be downloaded from the link below.