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December 11, 2008 2:21 AM

Mechanical Engineers: calculations for sealing an underwater enclosure ?

I'm designing an underwater enclosure for a movie camera, made from 1/4" Aluminum tubing. One end will be welded shut, but the other will have a removable cap with a gasket squished between two mating surfaces.

Assuming a maximum water pressure of 300psi, how do I calculate the required clamping force to keep the gasket seal in tact ? I can't quite wrap my head around the free body diagram....

posted by pickingoutathermos to Science & Nature (2 answers total)

Won't it be squished by the pressure difference?

I'm seeing a removable cap like a pipe cap over an opening. Pretty much any gasket will do the trick (black neoprene rubber will do nicely) make it 1/4" thick or so.

If you really want, I can give you the bolt tighness required by piping spec at 300psi with a standard fiber gasket... I may have rubber gasket tightness lying around, just give me the diameter.

If you have the picture of a sketch, or a sketch, feel free to send me an email.

*IAAME, and I like piping.
posted by defcom1 at 3:11 AM on December 11, 2008

The trick is to make the pressure work for you. There are a number of pressure-activated seal profiles available, or a carefully placed 'o' ring will self seal.

I would be more concerned with the loading on the tube and the welded end. Is the welded end going to be domed?

Pretty much any engineering handbook will have basic calculations. If I can help then send me more info (SI please tho!).
posted by BadMiker at 7:02 AM on December 11, 2008