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.