Pressure Testing Procedure for Industrial Valves

1. Introduction

Pressure testing is one of the most important quality control steps for industrial valves. It is performed to verify the strength and tightness of the valve body, sealing surfaces, and overall assembly before delivery and use. Testing ensures that valves can safely operate under their designated pressure ratings in real-world applications.

Typically, valve pressure tests include strength tests (shell tests) and sealing tests (seat leakage tests), performed according to standards such as API 598, ISO 5208, EN 12266, GB/T 13927.

2. Preparation Before Testing

1. Valve Inspection

   • Check appearance, dimensions, and markings.

   • Ensure the valve is clean, free of debris, and properly assembled.

2. Test Equipment Setup

   • Pressure test bench or hydrostatic test rig.

   • Calibrated pressure gauges (accuracy ±1%).

   • Water (hydrostatic test) or air/nitrogen (pneumatic test).

3. Connection

   • Properly install the valve on the test bench.

   • For flanged valves: use sealing gaskets and bolts.

   • For threaded/welded valves: use adapters.

3. Pressure Testing Procedure

3.1 Shell Strength Test (Hydrostatic Test)

• Purpose: Verify the valve body and bonnet can withstand pressure without leakage or deformation.

• Medium: Usually water at room temperature.

• Test Pressure: 1.5 times the rated pressure (PN or Class).

• Procedure:

  1. Fill valve cavity completely with water, expel air.

  2. Gradually increase pressure to the specified value.

  3. Hold pressure for 2–5 minutes depending on valve size.

• Acceptance Criteria: No leakage, sweating, or structural damage on body or bonnet.

3.2 Seat Tightness Test (Seal Test)

• Purpose: Verify sealing performance of valve seat against reverse leakage.

• Medium: Water (hydrostatic) or air (pneumatic).

• Test Pressure: 1.1 times rated pressure (API 598); or per order requirements.

• Procedure:

  1. Close the valve disc.

  2. Apply test pressure on one side of the seat.

  3. Check leakage rate at the opposite side.

• Acceptance Criteria:

  • Soft-seated valves: Zero visible leakage.

  • Metal-seated valves: Leakage rate must meet standard limits (e.g., API 598 allowable leakage).

3.3 Additional Tests (if required)

• Low-pressure air test: For precision sealing inspection (0.6 MPa air).

• High-pressure gas test: For valves used in gas service.

• Functional test: Verify smooth opening/closing, actuator performance, and torque.

4. Post-Test Handling

• Slowly release test pressure to avoid water hammer.

• Dry the valve interior (compressed air or nitrogen).

• Apply anti-rust oil if stored for a long period.

• Record test data (valve type, size, pressure values, duration, results).

5. Conclusion

The pressure testing of industrial valves is a critical quality assurance step that guarantees product safety and reliability. By following standardized procedures for shell strength and seat tightness, manufacturers ensure that every valve delivered to customers can withstand design pressures and provide reliable sealing performance in service.

YIXIN conducts 100% pressure tests on all valves according to API 598 / ISO 5208, ensuring each valve meets international standards before shipment.