Should the flare boundary valve of the unit be equipped with a single valve or two valves?
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As plants become larger, the diameter of the flare pipeline pipes in such plants exceeds one meter. In many cases, a single valve – usually a butterfly valve – is used together with an eight-shaped blind plate in these plant areas, which poses certain difficulties when it comes to installing blind plates in the plants (if the external pipeline system is developed rapidly, it may be filled with nitrogen or even fuel gas at the time blind plates are installed in the plant). What are everyone’s thoughts on this?
We have a dual-valve setup here, which allows nitrogen to be used to push out the medium.
We have installed a single valve, but the remaining process pipelines are designed with two valves, with purge steam added in between
This post was last edited by longziyun on 2020-7-13 at 23:15. Since butterfly valves are commonly used, it’s normal for large-diameter butterfly valves not to close tightly. If one valve doesn’t close properly, the same will happen with two valves as well. Therefore, there isn’t much difference between using one valve or two valves. For safety reasons, it is necessary to thoroughly purge and depressurize the system first, then take samples from the front and rear vent valves or drain valves. Only after the toxic gases have been confirmed to be within acceptable levels should a blind flange be installed; haste must be avoided at all costs. In most cases, construction work requires the use of cranes, multiple workers working together, as well as supervisors. If toxic gases spread, it’s possible that the people around won’t have time to escape, as human safety is of utmost importance.
Out of curiosity, are everyone’s double valves butterfly valves? Should it be a butterfly valve, or a gate valve?
In previous plants, the diameter of the flare pipelines was large, and double butterfly valves were used; however, the newly built plants use single butterfly valves
Once again, only what is more suitable and meets the on-site requirements will do.
Add double valves and 8-shaped blind plates; use nitrogen and steam for wire cooking