Full vacuum case for ASME B16.5 Standard flanges
Full vacuum case for ASME B16.5 Standard flanges
(OP)
can anybody tell how to select the rating of standard flange if there is Full vacuum case. there was no external pressure in pressure-temperature rating table. any help is appreciated.





RE: Full vacuum case for ASME B16.5 Standard flanges
Brian
RE: Full vacuum case for ASME B16.5 Standard flanges
I believe the standard flange should be able to withstand the full vacuum pressure without any failure. but is there any paragraph or code (evidence) stated that we just can selected it like this. is that rule of thumb?
RE: Full vacuum case for ASME B16.5 Standard flanges
Perhaps you could look at it from a loading perspective: As long as you seat the gasket, the operating (external) pressure will tend to add to the forces closing the flange pair together rather than opening them up. All you have to do is look at what the longitudinal stress is doing.
Seems to me that if the flange pair can handle 285 psig internal, its not too much of a stretch to believe that it can handle 15 psi external... though I searched for any official statement in B16.5 and couldn't find any...
jt
RE: Full vacuum case for ASME B16.5 Standard flanges
From the formulae of that paragraph it is easy to demonstrate that a flange designed for an internal pressure P will always withstand with margin the same pressure when external.
This result is quite obvious if you realize, as jte states with a different wording, that the bolts act as a support with external pressure, while their load add up to pressure load with internal pressure.
To give another reference:
prex
http://www.xcalcs.com : Online tools for structural design
http://www.megamag.it : Magnetic brakes for fun rides
http://www.levitans.com : Air bearing pads
RE: Full vacuum case for ASME B16.5 Standard flanges
rhg
RE: Full vacuum case for ASME B16.5 Standard flanges
What will be the gasket that you think suitable for vacuum service regardless of its temperature and pressure.
RE: Full vacuum case for ASME B16.5 Standard flanges
See precision rubber O-ring. Also see Flexitallic catalog
rhg
RE: Full vacuum case for ASME B16.5 Standard flanges