large volume pressure container ideas?

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PTJeff

PTJeff

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Joined
Jun 13, 2007
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Location
Berea, Ohio, USA.
I need/want to cast with pressure a sheet that would be 12" x 14" x 1" and have no idea about a pressure container. Shy of purchasing a bioengineering container at over 100K, any ideas out there?
 
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You might need to look into having a sheet metal fabricator help you out.
A simple box seems easy enough for them to make. You'd need to find
a way to secure a door and install fittings, but you can probably get
those parts locally.
 
OR...


Maybe one of those big turkey frying pots. You would have to have it modified, but maybe that would be easier than engineering a box, with fittings, and an opening that seals.


Take a HF pot, and cut the stuff off of it, and reweld it onto a turkey pot. tap the lid for fittings, and make a gasket inside teh lid.

I personally would have any homemade pressure pot tested before i used it. In fact, i would probably have it tested to double the pressure i wanted to use.
 
While I am a great supporter of DIY projects, I'm with Tom on this one. It sounds like a project that could earn you a nomination for a Darwin award or at the very least a virial YouTube segment. Somethings are better off not being attempted without the proper equipment. Just one man's opinion.

Jim Smith
 
Go to an army surplus store ask for a 30 mm ammo can. some are steel others are rigid plastic both have good rubber seals. It ma be used a few times or more.
Just a thought, Mark
 
If there is nothing going in the resin, you can probably get away with just vacuuming it first(if using PR) and then pouring it gently into the mold. You don't realy need the pressure.
 
For a pressure vessel with 12x14x1 dimensions pressurized to 30 psi, the force on the 12x14 side would exceed 5000 pounds. A flat side will not stay flat. The ammo can idea may hold the pressure, but you would have to support it at only the 4 corners to keep it from rocking and your mold will be sitting on a curved surface.
 
I don't think that an ammo can could hold anywhere near that pressure. The thin metal sides or the top would no doubt bow out causing seal failure, or worse.
 
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pssherman said:
For a pressure vessel with 12x14x1 dimensions pressurized to 30 psi, the force on the 12x14 side would exceed 5000 pounds. A flat side will not stay flat. The ammo can idea may hold the pressure, but you would have to support it at only the 4 corners to keep it from rocking and your mold will be sitting on a curved surface.
Click to expand...

I don't understand how 30 pounds of pressure can become 5,000 pound of pressure. ????
Color me confused.
 
288 square inches at 30 pounds per square inch = 8640 pounds of force on the side.
 
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I agree that using any container for pressure that is not designed for it is a very risky endeavor. Keep in mind that pressurized containers all have round edges for a reason. Anything with a point (i.e. corner) is inherently NOT strong enough for that kind of pressure. However, that calculation of over 4,000# is a total amount on the whole area. The amount on any given spot is force/area. So, if you are looking at a one square inch area, its really only is 30psig/1sq-in, or 30lbs force. The analogy I love is the example of a woman's high heel. This is in no way meant to be sexist. If you take a 120lb woman with a heel point that has an area of 1/2 sq-in, and do the math, that is 240 lbs per sq-in. Now, take a big guy, at 240 lbs, with a size 12 shoe. Lets estimate that shoe area to be roughly 36sq-in (3"x12"), do the math [240lb/36sq-in] you get 6.67 lbs per sq-in. See the difference?

I guess what I am saying that, a small sharp point will have much more localized force on it than a wide sweeping curve.

Anyway, I recommend using a vessel that is design for pressure. The Darwin statement hit the nail on the head.
 
When I made the suggestion about a metal fabricator, I just ASSUMED they would
be told what it is for and design it appropriately. If someone can't make a weld to
withstand 30 or 40 psi, perhaps they wouldn't be working in metal anyway.

I suppose he could get a really really big truck tire and put his casting in that.
I know those are designed to hold 30-40 psi at least..
 
I cannot check my previous posts at this time, but I posted a website in a thread of a company that sold VERY large pressure containers. Still a bit pricey for the average user, but less than the amounts mentioned in the original posting to this thread
 
OMG Mike, that's a big pot.

Thanks to all who have supplied input to my query.

So far there have been a few good ideas, but sadly enough, it looks like i'm going to have to re-design my cast and make alot of small runs. I like the idea of setting the can on it's side and make a cradle of sorts to prevent rolling and clear lid for opening and closing.

I'm moving away from PR due to the LOML nearly killing me. Thank goodness the fumes made her a little slower ;}

wolftat: the vacuum brings the saturated gas out of solution and the pressure will compress any bubbles left to negligable size and or prevent additional gas from coming out of solution (depending on what book you read)
 
NewLondon88 said:
When I made the suggestion about a metal fabricator, I just ASSUMED they would
be told what it is for and design it appropriately. If someone can't make a weld to
withstand 30 or 40 psi, perhaps they wouldn't be working in metal anyway.

I suppose he could get a really really big truck tire and put his casting in that.
I know those are designed to hold 30-40 psi at least..
Click to expand...

It's called liability......it's a whole different animal when you're into vessel welding. It's not simply the welding of two pieces of metal together....not just anybody can weld vessels. There's a lot to it......not done properly, you can actually weaken the metal or have a weld that won't hold at pressure. Think SAFETY, SAFETY, SAFETY!!!


Barney
 
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