vacuum vessel

[tuizner]

Hi

Could anyone tell me how to go about designing a vacuum chamber (cylindrical)?

I wish to use a paint pressure container (310mm dia,450mm length, 3mm steel) which has domed endcaps - but how do I assess its suitability to withstand a full vacuum?

Are there simplistic equations to use? The end caps are very thick (15mm-20mm) compared with the wall thickness of the cylinder (3mm).

Thanks

 

[prex]

I guess that you are comfortably on safe side.
The critical pressure of an infinitely long thin cylinder is given by:
p_cr=2Et³/(1-&[ignore]nu[/ignore];²)D_e³
and you should take a factor of safety of 3 with respect to it.
As your cylinder is quite short, an added high factor of safety is implied in such a simplistic approach. However the formulae for short cylinders are too complex to be reported here. I think that Roark has an approximate formula for short cylinders.
Don't forget that to have a safe vessel you also need a correct joint between cylinder and heads.

prex

http://www.xcalcs.com

Online tools for structural design

 

[unclesyd]

This is one website you might try

http://www.rathmfg.com/collapsingpressure.htm

 

[MJCronin]

tuizner,

The most referenced source for design is the ASME Boiler & Pressure Vessel Code, Section VIII; Division I

There are several books that provide a simplified description of design methods and design calculations for vacuum design of pressure vessels. One of which is the "Pressure Vessel Handbook" by Eugene F. Megyesy
(now in 12th edition)... pricey, at about $160

http://shop.store.yahoo.com/pennwell/presveshan11.html

Or consider the "Guidebook for the Design of ASME Section VIII Pressure Vessels, Second Edition" by James R. Farr and Maan H. Jawad. A less expensive but, in my opinion, very well written and informative text.......

http://www.asme.org/pvp/pvpbook1.html

Hope that this helps

MJC