Cryogenic joints sealing

>>>...'I am designing a process that uses repetitive cooling of the material to -150C followed by heating it back to 10C many times in a row.....

.....I expect about one hundred cycles a day on a continuous basis. Hopefully for 10-20 years.'....<<<

Why?

I understand your curiosity but cannot divulge the details of the process until a patent has been applied for. Sorry.

Hi, i see your in Canada... I think looking at vacuum chambers and vacuum systems for your process would be your best option. I know that they use vacuum in similar applications so I would guess that it could be used in yours. I would suggest getting a hold of Joey Keller from Kurt J. Lesker Canada at 1-800-465-2476 (tell him Roy from AVP Technologies Inc. sent you.) and see what he has to say. When it comes to systems he's the guy in Canada to talk to, in my opinion you will get more honest info from him than you will anyone else in the industry in Canada. When and if you do buy your system keep me in mind for service.

Good luck my friend.

You have no idea what he's talking about. Salesmen should not be allowed on CR4.

I'm not a salesman by any means and if I misunderstood what this person is asking then that's his decision to tell me or not. Considering you are posting anonymously. I figured if I could help than I would. As I read the post he's asking for the best material to handle his process, if his process is done under vacuum than the temperatures needed to can be lower due to the lack of atmosphere. I'm a service engineer, not a salesmen, I don't know much about his application or what he is trying to accomplish, and I didn't pretend to. My post was based on giving him some info and pointing him in a direction he may not have looked at. (To the original poster, I apologize for the use of "him" in this post if your a woman)

If you have so much knowledge then I would suggest a contructive post as opposed to belittleing somone.

Thank you Simple1.

I appreciate the suggestion and will probably contact this person. I don't understand why Guest is negative about your suggestion.

Thank you.

Hi Joe,

Long time.

SC

Marcot, how much thermal stress is the material subjected to for 160 degrees C temperature differential? Can't be that much, think about it. Tea kettle goes from 20 to 100 C.

Yes, but it doesn't have to be sealed for two bars. My concern it with screwed in connectors that would loosen over time.

I am electrical by trade. I don't have any idea how the welded joints will hold over time. Maybe it will be OK. That is why I ask people with experience in this field.

Thank you all.

Marco

That would depend on the type of weld material, I do work for a Turbine company that heat treats (under vacuum) at 2500 degrees Celsius and they have no problems with there chambers. I know that I personally have used nickel welding for high heat and had good success in the past but i can't say for sure whether it would work under cold temps.

At cryogenic temperatures, most gasket materials become brittle. Rubbers are completely useless.

So do most metals, eg mild steel becomes as brittle as glass.

Aluminium and copper hold their ductility down to close to absolute zero and are good choices.

Austenitic stainless is supposed to be OK, but I have some doubts about austenite eventually transforming to martensite, with the attendant brittleness developing.

I know nothing about your particular configuration, but I would be inclined to make your apparatus out of welded aluminium, using soft Al or Cu as gaskets and bolting or strongly clamping your "lid" shut.

Stress relief is always desirable, and may be necessary here.

Good luck

Thank you. I like this suggestion.

http://atlasuhv.com/products/bimetallic_couplings/aluminum-stainless/index.php