Regarding vacuum tubes
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I currently have a low-vacuum system at room temperature (absolute pressure of 17 kPa), and pipe connections are needed. The question I have right now is whether it is possible to use conventional raised-face flanges (HG20592) along with rubber gaskets for sealing This makes it easy to match with relevant valves, instruments, etc. Are there any peers with similar experience that can serve as a reference? I would be grateful for your guidance
I found some information online; here is a statement for reference: “At low pressures (especially below 0.6 MPa) and in vacuum conditions, it is more appropriate to use rubber gaskets.” Rubber materials have good density and low air permeability. For example, fluororubber is the most suitable material for gaskets in vacuum vessels, enabling vacuum levels as high as 1.3×10-7 Pa. When rubber gaskets are used in a vacuum range of 10-1 to 10-7 Pa, they need to be baked and evacuated. ”
Yes, rubber pads can definitely be used in a vacuum environment. I’m not sure if regular flanges can be used; vacuum flanges cannot be paired with valves and instruments
Tetrafluoro gaskets are better; they do not age over time, unlike rubber gaskets.
So do you think ordinary raised-face flanges can be used for the flanges on low-vacuum pipes?
Vacuum pipes can use raised-face flanges; for pipes at -0.05 MPaG, we use raised-face flanges along with wound gaskets.
Thank you! Your engineering experience is very important
Non-metallic gaskets can be used, but metal-edged non-metallic gaskets are preferred； Or use a metal wound gasket directly ； In a vacuum, ordinary non-metallic gaskets tend to scatter.
Our two devices involve vacuum systems, and the vacuum level is much lower than yours. Gauge pressure of 7 KPa and 13 KPa. Ordinary WN-RF flanges are used; almost all of them feature metal wound gaskets, with only a few using PTFE gaskets. I haven’t read much on this topic, but I think that the force exerted by a system with zero gauge pressure on the side of the gasket is equivalent to the force exerted by a system with 1 gauge pressure on the other side of the gasket. How is it possible that one side can withstand the force while the other cannot? Gaskets and flanges are not that delicate. A pressure of 1 kilogram can be roughly held back with the hand.
Thank you. I’m not worried about seal failure; I’m concerned about the hassle of matching the pipe fittings
It is best to use gasket plates with uneven surfaces, and PTFE is a good choice, as gaskets tend to age when exposed to air for long periods of time.