How to calibrate the safety valve of a pressure vessel?

I. Preparation before calibration

Equipment inspection: Confirm that the calibration bench, pressure gauge, and other tools are in good working order.

Visual inspection: Check the nameplate and valve body for rust, and ensure that all parts are complete.

II. Set pressure test

Installation: Secure the safety valve to the calibration bench.

Pressure increase: Slowly increase the pressure to 90% of the set pressure, then increase the pressure at a rate of ≤0.01 MPa/s.

Record: Record the pressure value when you hear continuous discharge of the medium. Repeat 3 times and take the average.

III. Reseating pressure test

Pressure reduction: Slowly reduce the pressure from the set pressure.

Record: Record the pressure value when the safety valve is closed.

IV. Sealing test

Pressure: Check the sealing surface below 90% of the set pressure.

Standard: When the set pressure is ≤0.3 MPa, the sealing pressure is 0.03 MPa lower than the set pressure; when >0.3 MPa, the sealing pressure is 90% of the set pressure.

V. Adjustment and Re-inspection

Adjustment: Correct the pressure value by adjusting the spring tension or the position of the counterweight.

Re-inspection: Repeat the test until it passes.

VI. Seal and Records

Seal: Seal the vessel after it passes to prevent adjustment.

Records: Archive data such as starting pressure and reseating pressure.

VII. Calibration Cycle

New Shipment: Calibrate before use if necessary.

Periodic: Perform according to the "Periodic Inspection Rules for Pressure Vessels".

VIII. Precautions

Media: Air or nitrogen is commonly used.

Safety: The vent should face away from personnel; keep your head away from the top of the safety valve.

Environment: Prevent corrosion and jamming; keep the vent clean.