Regarding 18442 helium leak detection
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According to clause 11.1 of GB/T18442.4-2011, before assembling the inner container with the outer shell, helium mass spectrometry leak testing should be conducted on the inner container, the outer shell, and the pipelines within the vacuum jacket. When using a helium mass spectrometer for leak detection, isn’t it necessary to connect the leak detection port to the vacuum valve of the container? When testing for leaks in the inner container, all pipelines are sealed off, with a temporary vacuum valve being welded in place; vacuum is created, and helium is introduced from the outside through a cover to detect leaks. So how is leakage detected in the outer shell? Before assembly, the end cap of the outer shell hasn’t been welded yet – both the cylinder and the end cap are separate components. How can vacuum be created to detect leaks in such a situation? Could you help analyze this? Is it my misunderstanding of this sentence, or are our leak detectors too outdated? Are there any leak detectors that can detect leaks without the need for vacuuming?
I don’t understand; I hope someone knowledgeable can answer this. I’m trying to learn**
All leak detection jackets must be evacuated. After the inner tank has passed the tests, the jackets are assembled; only after this assembly is complete can leakage testing of the outer tank be carried out. The purpose of leak detection is to ensure that there are no leaks in the jackets, while the vacuum in the jackets is intended to prevent the temperature of the medium inside the tank from changing rapidly due to natural heat exchange. Generally, a jacketed vacuum vessel can maintain the temperature of the inner tank for 4-5 days after adjustment is completed (with no medium in the inner cylinder).
Our casings are helium-tested after being put into the throwing sleeve