1. Pre-Installation Testing  

   Before installation, safety valves must undergo pressure resistance testing and leak-tightness testing to verify structural integrity and sealing performance. Only after passing these tests can calibration and adjustment proceed.  

2. Setting the Opening Pressure  

   On a gas test bench, adjust the load applied to the valve disc to calibrate the opening pressure:  

     Lever-type safety valves: Adjust the position of the counterweight.  

     Spring-type safety valves: Modify the spring compression.  

     The set pressure must comply with boiler and pressure vessel safety regulations.  

3. Adjusting Discharge & Reseating Pressure  

   On the actual vessel, fine-tune the discharge pressure and reseating pressure by adjusting the clearance between the adjusting ring and the valve disc.  

   Symptoms of improper adjustment:  

   Excessive clearance: Valve leaks at opening pressure but fails to lift, or causes severe vibration/"chattering" after lifting. → Reduce clearance.  

     Insufficient clearance: Reseating pressure is too low. → Increase clearance slightly.  

   Allowable pressure limits:  

     Steam valves: Discharge pressure ≤ 1.03× opening pressure; Open-close differential ≤ 10% of opening pressure.  

     Air/gas valves: Discharge pressure ≤ 1.10× opening pressure; Open-close differential ≤ 15% of opening pressure.  

4. Calibration Requirements  

   Must be performed in the presence of the user’s safety technician responsible for boilers/pressure vessels.  

   Use Grade 1 or higher precision pressure gauges for adjustment.  

   Live (in-service) calibration requires safety precautions.  

5. Post-Calibration Protocol  

   Maintain detailed calibration records.  

   Seal calibrated valves with lead seals after installing accessories to prevent unauthorized adjustments.