Is it necessary to conduct a leak test on atmospheric storage tanks with nitrogen sealing?
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It is a pressure vessel with a flat-bottomed conical top; the design pressure is 6 kPa, and a nitrogen seal has been installed as required by the process. Is it necessary to conduct a airtightness test after the hydrostatic test? Some people believe that in pressure vessels at normal pressure, where the pressure is relatively low, there are basically no issues with tightness, so it is not necessary to conduct a airtightness test. There is another view that, due to the nitrogen seal, a leak test should still be conducted to ensure that nitrogen can effectively seal everything in place. Such flat-bottomed conical-top storage tanks are generally manufactured on-site in harsh construction conditions. Should a leak test be conducted? Furthermore, is it difficult for the construction party to carry out the airtightness tests on site? Are there any obstacles regarding tools, instruments, equipment, etc.?
Personally, I don’t think it’s necessary to achieve airtightness; the purpose of nitrogen sealing is to prevent moisture from the atmosphere from getting in. Even if there is a slight leak, that’s fine as long as a slight positive pressure is maintained
In other words, even micro-leaks cannot maintain the pressure required for nitrogen sealing?
GB50341 does not specify anything; it only states that fixed roofs should be tested using the vacuum chamber method or a airtightness test.
The vacuum chamber method can only inspect the bottom of the tank; it’s ineffective for the corner welds on the top of the tank
The pressure vessels we manufacture with nitrogen sealing do not require a gas-tightness test.
Our atmospheric-pressure ones don’t have any requirements~~~~~ They’re generally not made·~~
Mm. What was said on the 2nd floor makes sense; indeed, not many pressure vessels are designed to be airtight.
The fillet welds on the top of the tank can also be inspected using a vacuum chamber; an angular vacuum chamber is sufficient for this purpose. It is this type of vacuum chamber that is used to inspect the large fillet welds on the tank walls and bottom.
A slight leak is not a problem; if it is detected that the nitrogen seal pressure is low, simply increase the nitrogen pressure in the main pipeline to maintain the desired seal pressure.
In other words, can the tank top, pipe walls, and tank bottom all be inspected using a vacuum chamber?