Gasket Material for Aluminum to copper at -196C

T

TwoC400s

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Jul 19, 2024
Messages
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I have an interface where an aluminum square tube (~3mm wall thickness) and copper base plate make a fairly loose mounting surface. It's designed to use a fairly thick thermal paste as a sealant (which is supposed to be re-applied regularly), but was wondering if there was a gasket material I could use instead.

When combined, the tube and baseplate form a container for LN2.

I would prefer to cut a gasket for it (I have access to a laser cutter), but if there's an "RTV-like" substance that would work well in those temps...I'm listening.

Also, it will temp cycle between ambient (~20C) and -196C regularly.
 
Contact a University Physics Department.

They will typically have one or more faculty/staff members that uses liquid N2 to cool some of their instruments used in their research projects. These guys will know what to use since they typically design and build much of their custom equipment.
 
TwoC400s said:
I have an interface where an aluminum square tube (~3mm wall thickness) and copper base plate make a fairly loose mounting surface. It's designed to use a fairly thick thermal paste as a sealant (which is supposed to be re-applied regularly), but was wondering if there was a gasket material I could use instead.

When combined, the tube and baseplate form a container for LN2.

I would prefer to cut a gasket for it (I have access to a laser cutter), but if there's an "RTV-like" substance that would work well in those temps...I'm listening.

Also, it will temp cycle between ambient (~20C) and -196C regularly.
Click to expand...
After a little digging apparently this is what is recommended "Handling liquid nitrogen demands a gasket material with excellent low-temperature performance. If an elastomer is needed Santoprene® may be a good choice. A trade name for a class of thermoplastic vulcanizate (TPV) materials, this behaves much like EDPM but some grades remain flexible at even lower temperatures.". Worth a shot.
 
In the aviation world, it is very common to see -70ºF temps in cruise flight. While not as cold as liquid nitrogen, having the ability to properly seal pressurization and deice ductwork at those cold temperatures is critical. For ducting, we tend to use high durometer silicone O rings, captured mechanically. Backed up by PTFE seals, either against the O-ring (the old way) or under the screw on cap, as a secondary seal (common today)

I have some GoreTex sheet gasket material which appears to be a foamed product. I've used it for all manner of crazy projects that don't see much pressure differential. It seems to hold up very well, and tolerate temperature extremes. Don't recall where I sourced it from, probably a sample from the NBAA convention a number of years ago. It is neat stuff.

The Av-DEC company makes some amazing gasket materials. Many are soft polyurethane captured in a weave of some sort. They are capable of very cold temperature use and perfect sealing to prevent corrosion and pressurization loss in the fuselage to antenna interface.

https://www.avdec.com/

Are you anywhere near South Florida? I could give you a few (admittedly old) samples I have.
 
Kestas said:
Is the connection a clamped joint? Just thinking out loud here... how about using lead as a gasket?
Click to expand...
it's simply held on by 1) the downward pressure of the weight of the aluminum tube, and a couple of set screws that keep it upright on the base.
 
97prizm said:
After a little digging apparently this is what is recommended "Handling liquid nitrogen demands a gasket material with excellent low-temperature performance. If an elastomer is needed Santoprene® may be a good choice. A trade name for a class of thermoplastic vulcanizate (TPV) materials, this behaves much like EDPM but some grades remain flexible at even lower temperatures.". Worth a shot.
Click to expand...
I looked at a sheet of Santoprene, and it lists specs of down to only -60C.

https://www.santopseal.com/product/...e-rubber-sheet=0-5mm-thick-x-11-wide-5ft-long
 
Cujet said:
In the aviation world, it is very common to see -70ºF temps in cruise flight. While not as cold as liquid nitrogen, having the ability to properly seal pressurization and deice ductwork at those cold temperatures is critical. For ducting, we tend to use high durometer silicone O rings, captured mechanically. Backed up by PTFE seals, either against the O-ring (the old way) or under the screw on cap, as a secondary seal (common today)

I have some GoreTex sheet gasket material which appears to be a foamed product. I've used it for all manner of crazy projects that don't see much pressure differential. It seems to hold up very well, and tolerate temperature extremes. Don't recall where I sourced it from, probably a sample from the NBAA convention a number of years ago. It is neat stuff.

The Av-DEC company makes some amazing gasket materials. Many are soft polyurethane captured in a weave of some sort. They are capable of very cold temperature use and perfect sealing to prevent corrosion and pressurization loss in the fuselage to antenna interface.

https://www.avdec.com/

Are you anywhere near South Florida? I could give you a few (admittedly old) samples I have.
Click to expand...
I'm in MD, but I appreciate the offer and the info.
 
Have you tried contacting your nitrogen supplier to see what they use for gasketing? Air Products, Air Liquide, etc.

I don't have access to my old piping specs to look up what we used at the oil refineries, darn the luck. Never felt I'd need to look at that in retirement.
 
I contacted the manufacturer and lo and behold, they do on occasion make custom gaskets upon request. They use PTFE.

Their quoted price seemed pretty steep though. I may see if I can get a sheet of Gore GR and cut my own.
 
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