Aluminum alloy for plate under vacuum 1

[drodrig]

Hi there,

I am looking for an aluminium alloy with a high yield strength for an end plate for a vacuum chamber (it has to take 1 bar - 14.5 psi)

The outer diameter is 2500mm (8.2 ft)

The thickness is what I am trying to determinate (between 50 and 25mm / 1 inch-0.5 inch)

What alloy would you recommend?

We have some experience with type 5754 but for thick plates the yield strength is not so attractive

thanks

 

[Compositepro]

I think that 6061-T6 is one of the most common alloys that would be used.

 

[SnTMan]

one inch ain't gonna get it....

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[Compositepro]

Vacuum chambers are often made from a grid structure of heavy ribs which supports relatively thin skins.The skins can even be clear plastic or glass plates. The controlling design issue is usually deflection, or stiffness, of the structure rather than stregth. A grid design can use much less maaterial, and therefore be significantly lighter and cheaper.

 

[WKTaylor]

Dd...

Does this pressure bulkhead have-to-be dead-flat... or can it be dome shaped?

Welded or Bolted/gasketed [permanently fixed]... or movable [door]?

Solid/monolithic... or machined-out [waffle/grid integral stiffeners].

Interior temperature: Room, Cryogenic, Hot? Chemicals or metals exposure?

Method of analysis? Safety factors? Material and Rigidity of the attached vacuum pressure vessel?

Fail-safe-mechanism for returning to ambient pressure?

WHY ALUMINUM????

Etc.




Regards, Wil Taylor
o Trust - But Verify!
o We believe to be true what we prefer to be true. [Unknown]
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[drodrig]

Hi,
the 6061-T6 seems a good candidate 275 MPa - 40 ksi yield strength

1 inch would have a maximum stress of 145 MPa - 21 ksi

The radial ribs is an option; we want to use thin windows for particles (high particle particles, they need a clean path) to go through

We are considering making a carbon fiber dome-shaped cap. This would decrease dramatically the stresses (hoop stress)

 

[SnTMan]

Flat head? Hoop strress? Hmmm...

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[drodrig]

dome-shaped

 

[mighoser]

How many do you need to make?

________________________________________
Mitsubishi Chemical Advanced Materials

http://www.mcam.com

 

[drodrig]

one

 

There's a reason pressure vessels are spherical and cylindrical! Stresses at corners quickly become ridiculous. Have a look at Subsection NE to learn how much the ASME Code punishes you for trying.

A higher strength aluminum helps of course but the bulging will be the same (i.e., obvious and concerning to a bystander!) since it depends on elastic modulus.

Back to the drawing board, which should be the only flat thing in your project.

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."