Tightness inspection method
1. Bubble method
Principle: Immerse the pressure vessel in water or apply soapy water to observe whether bubbles are generated. Suitable for tightness inspection of liquid media.
Advantages: intuitive and simple, low cost.
Disadvantages: Not suitable for detection of high-pressure systems or toxic and hazardous media.
2. Pressure test method
Principle: Apply a certain pressure inside the pressure vessel and then observe its sealing performance. Suitable for containers that need to withstand a certain pressure.
Advantages: Suitable for most industrial equipment and can detect larger leaks.
Disadvantages: Low detection sensitivity for small leaks.
3. Vacuum test method
Principle: Place the pressure vessel in a vacuum environment and judge the tightness by detecting the change in its internal pressure.
Advantages: Suitable for equipment that needs to work in a vacuum environment.
Disadvantages: High equipment cost and complicated operation.
4. Helium leak test method
Principle: Use helium as a tracer gas. After applying helium inside the equipment, use a helium mass spectrometer to detect whether there is helium escaping from the outside.
Advantages: extremely high sensitivity, suitable for detecting tiny leaks.
Disadvantages: expensive equipment and complicated operation.
5. Ultrasonic leak test method
Principle: turbulence generated by the leak point will generate ultrasonic signals, and a dedicated ultrasonic detector can be used to locate the leak.
Advantages: non-contact measurement, suitable for detection in difficult-to-access areas.
Disadvantages: may be interfered by background noise.
6. Pressure decay method (pressure drop method)
Principle: Compressed air or nitrogen is filled into the object to be tested, and the pressure changes over time are monitored. If the pressure drops by more than the threshold, a leak is determined.
Advantages: high accuracy and simple operation.
Disadvantages: The ambient temperature needs to be strictly controlled, and temperature changes will affect the pressure.
Sealing test process
1. Preparation
Determine the test standard and select the appropriate international or industry standard according to the equipment type and application scenario.
Thoroughly clean the equipment to be tested and perform a preliminary visual inspection.
Prepare necessary tools and materials, such as pressure gauges, vacuum pumps, helium leak detectors, soap and water solutions, etc.
2. Design the test plan
Determine the test method, such as air tightness test, water tightness test, helium mass spectrometry leak detection, etc.
Set the test parameters, including test pressure, temperature, duration, etc.
Develop safety measures and consider the possible risks under high pressure or vacuum conditions.
3. Install the test device
Connect the pressure source or vacuum pump.
Install sensors and monitoring equipment.
Seal all openings to ensure a closed system.
4. Perform the test
Slowly increase the internal pressure or reduce the internal pressure to a predetermined value.
Keep the device under the set pressure or vacuum conditions for a period of time to observe whether there are signs of leakage.
5. Detect the leak point
For air tightness test, soapy water can be applied to the joints to observe whether bubbles are generated; or helium mass spectrometry leak detection technology can be used.
For water tightness test, directly observe whether there is leakage.
6. Data recording and analysis
Record the pressure changes, temperature fluctuations and other relevant parameters during the test in detail.
Compare the actual measured values with the preset standards to determine whether the equipment meets the sealing requirements.
7. Repair and retest
Accurately mark all leak locations found.
Choose the appropriate repair method according to the specific situation.
After the repair is completed, perform the sealing test again until the specified requirements are met.
