In gas pipeline engineering, due to various factors during construction, there may be small holes at the connections of some pipelines that are difficult to detect with the naked eye, which can cause leaks and accidents during use. Especially in the microelectronics industry such as semiconductors and integrated circuits, if a leak occurs, the gas pipeline engineering that transports ultra-high purity electronic special gases will have a significant impact on production safety, so leak detection is very important.

One What is commonly referred to as helium testing?

Firstly, we need to understand that the five tests for gas pipelines are the most important part of QC, including pressure holding test, helium leak test (helium detection), moisture test, oxygen content test, and particle test, to ensure that the quality of the gas pipeline system reaches a certain level and meets customer needs.

II How is helium gas leak detected?

As is well known, in the periodic table, helium (He) has the smallest relative molecular weight after hydrogen (H) and is the lightest inert gas. The helium leak detection of gas pipelines utilizes this.

1. The helium leak detection methods for high-purity bulk gas pipelines should use inward leak detection method, valve seat leak detection method, and outward leak detection method.

2. Internal leak detection method (helium injection method) is carried out by inhaling high-purity gas pipeline internally and injecting helium gas externally

3. The method of detecting valve seat leakage must be filled with helium gas in front of the valve and evacuated downstream

4. It is necessary to use the outward leak detection method (suction gun method) to fill the high-purity gas pipeline with helium or helium nitrogen mixture, and use an external suction gun to check for possible leakage points

5. The helium leak detector must be a mass spectrometer helium leak detector with a detection accuracy of not less than 1

6. The leakage rate of high-purity helium gas leak detection should meet the following requirements:

(1) The leakage rate measured by the inward leakage detection method shall not exceed 1.10-9 mbar l/s

(2) The leakage rate measured by the valve seat leakage detection method shall not exceed 1.10-6mbar l/s

(3) The leakage rate measured by the outward leakage detection method shall not exceed 1.10-6mbar l/s

7. After repairing the leakage points discovered by helium leak detection, a new airtightness test must be conducted. After passing the test, helium leak detection can be carried out according to regulations

8. All possible leaks should be insulated using plastic bags

After system testing, fill and clean with high-purity nitrogen or argon gas

10. After inspection, a test report should be submitted