Shutdown Purging time
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Shutdown: Why is the purging time for process pipelines, towers, and vessels 48 hours? How is this determined? !
The purging process should not be determined by time, but mainly by the results of the final gas testing; it is also influenced by the size of the purging system and the gas flow rate； Of course, some companies determine a purging time based on past practical experience ； Perhaps your company falls into this category
48 hours is an empirical value; generally, 48 hours of continuous purging is sufficient to ensure compliance, but ultimately it still depends on the purging method and the results obtained with that method.
This can only be based on relevant standards; for example, pipelines are governed by GB50235, stations by GB50540, and containers by GB150, etc. It’s not something that is invented arbitrarily
Our company’s approach is to first establish an empirical value, then take samples for analysis when the time comes; if the results are not satisfactory, the purging process continues. Samples are taken every 2 hours until the purging is successful.
It is possible that the extended purging time is due to the presence of fillers and catalysts in the device, which tend to volatilize after purging
Time should not be used as a criterion~~ Analysis must be carried out at fixed times and in specific locations to ensure that the replacement is completed properly and that the levels of hazardous substances are within acceptable limits~~ Sometimes, it is possible to stop the supply of gas by replacing certain pipelines and devices first, thereby saving gas~~
I want to know the answer too. Is there a specific reason?
48 hours is just an empirical value; it may only be applicable to the operational requirements in your area. That is, after ensuring 48 hours of purging, under normal circumstances, it is generally sufficient to achieve the desired purging objective! In practical operations, we must take into account multiple parameters, such as pressure, temperature, and composition!
Experience value: if the sample is unsatisfactory after 48 hours, further purging is required~~~~