This article is about how to perform calibration of Pressure Relief Valve or validation and setting the pressure of relief valves.
Calibration of Pressure Relief Valve
- Prior to testing the relief valve shall be subject to thorough visual inspection for any obvious surface
- The valve shall be mounted on the rig.
- Test gauges for checking the set shall bear± 3 %.
- The testing pressure shall be increased gradually until the valve lifts at the cold set pressure specified on the data sheet.
- After successful testing of the cold set pressure, the valve shall be subject to a seat tightness test.
- The applied pressure of the testing medium shall increase gradually to 90% of the “COLD SET PRESSURE”.
- The test result shall be recorded.
- Acceptance criteria for a valve with metal sat the leakage rate in bubbles per minute shall not exceed in 50 % of the appropriate value in API standard Table 1. For soft seated valve there shall be no leakage for 1 minute (0 bubbles per minute).
- All tested PRVs should be mechanically sealed immediately after testing has been completed with seal wire lock punch.
- Each PRVs shall assigned with serial number for tracking and record (SAEP-318).
- Each PRESSURE RELIEF VALVE shall have a history log file in Calibration Shop. This file should include the PRESSURE RELIEF VALVE Engineering date, and components (i.e. spring), changes and
- Test PRESSURE RELIEF VALVE used for PRESSURE TESTING shall be identified with corrosion resistant metal tag as description, and stamped as follows:
“TEST PRESSURE RELIEF VALVE”
- Gently operate the pnuematic pump comparator to achieve the desired set pressure.
- Once reach the desired set pressure, the PRESSURE RELIEF VALVE should open or The PRESSURE RELIEF VALVE shall open or pop ONLY at the desired set pressure.
- In case the PRV does not open or pop on the desired set pressure ( more or less then the desired pressure), depressurized the pneumatic pump comparator and carefully remove the PRESSURE RELIEF VALVE from the test ri
- Subcontractor are not allowed to modify spring ranges or any modification, subcontractor has to go third party calibration agency if PRV fail due to spring/technical issues.
- Result of the test shall be filed and recorded on the applicable test result form.
- All successfully tested PRV shall be identified with a color code
- The calibration validity will be 7 days from the start of calibration acceptance.
We linked following video for your practical consideration and theoretical consideration.