Why isn’t a vent provided at the top of this expansion joint?
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Isn’t it said that exhaust needs to be released at high points?
Generally, a temporary vent valve is installed during pressure testing, and it is removed after the testing is complete. If a vent valve remains in place, it creates an additional point of leakage; it may also be accidentally opened by someone who is not aware of its presence, leading to leaks. Additionally, it facilitates oil theft in the case of oil-based products
If it is a gas medium, there is no need to set it either
These are most likely steam pipes that haven’t been insulated yet. The exhaust valve seems to be of little use; it’s better not to have it, as operating it can be very dangerous
I don’t think it’s a steam pipe; there’s no drain at the lower end.
What medium is in the pipeline? ? Gas bar
Before using this pipeline for the first time, it needs to be pressure-tested, and this expansion joint can be removed; by removing it and testing each part separately, there is no need to install a vent valve； After normal operation, since the pipeline is a thermal pipeline with a pressure generally above 6 KG, the air inside the pipeline can be completely expelled. Installing an exhaust valve is not only unnecessary but also adds many additional static sealing points, which is utterly redundant.
It’s probably the residual gas in this small section; it has little impact on the pressure testing, after all, the pipeline is quite long. Gas dissolves in water under pressure; as the temperature rises or falls, the pressure inside the pipeline increases or decreases relatively quickly, and overpressure may occur. Installing a safety valve can provide protection against this. For a simple check of the weld’s pressure resistance, this high-point venting can be ignored.
Agree with the person in floor 3; this is probably just due to thermal expansion and contraction, not exhaust
Vent the air during pressure testing; otherwise, there will be air in between