Venting and drainage
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Installing venting facilities at the high points of pipelines and drainage (backflow) facilities at the low points is a basic principle in pipeline design. If there are no venting facilities at the high points and no drainage facilities at the low points, the medium will accumulate at those points when the installation is shut down. If the medium is toxic, it can cause poisoning in operators or maintenance personnel. If the medium is flammable and explosive, it may catch fire or explode due to hot work. When there is no vent at the highest point of the pipeline, and if the medium inside the pipeline is a liquid, it can cause gas blockage in the pipeline during normal operation. If this gas blockage occurs at the pump inlet, it can lead to the pump being starved of fluid. When there is no drainage at the lowest point of the pipeline, it may lead to freezing and other issues in the pipeline. All these issues will affect the production operations of the device.
This post was last edited by ylb913 on 2015-6-24 06:25. When installing piping, efforts should be made to avoid the formation of air pockets; generally, the gas will gradually be expelled on its own, and it’s rare to use vents at higher positions. Look at the system pipes – with all those support structures, how many of them have vents at higher levels?
What do you mean by air bubbles appearing in the piping?
air pocket. In other words, there is gas accumulated at the highest point, which is carried away as the medium flows.
The pipes on our equipment generally have drain valves at their lowest points, while vent valves at the highest points are usually only found on steam pipes!
It’s not that all pipes need to be equipped with high-point vents and low-point drains. The operating conditions must be taken into account; if the medium in the pipeline tends to cause clogging, line cleaning is definitely necessary when shutting down the system. Import and export pipelines for general equipment are equipped with high-point vents and low-point drains, either for equipment maintenance or to prevent air blockages
Nothing is absolute. It depends on how the design firm approaches the design and whether the client has any objections. There are certain things, such as the backwashing and venting mentioned by the poster; it’s not necessary to have them in every location, but their absence can cause problems for the operators later on or even pose safety risks.
It makes a lot of sense; it’s just a requirement of normal design, while special cases are another matter.
I’m a bit confused: before handing over combustible or toxic gas pipelines for maintenance, a chemical transfer procedure must be carried out. It is necessary to use inert gases to displace the gases present, and maintenance can only proceed after it has been confirmed that the levels of combustible or toxic gases are within acceptable limits. Therefore, I personally believe that it is unnecessary to install a vent at the highest point of the pipeline, especially in gas pipelines, where it is even more redundant.