Tig on dewar

steamer · 2005-07-21T17:48:38+00:00

--A pal of mine by the name of Roger Gregory ( is messing around with rotary-pumped rocket motors. He wants me to weld a stainless fitting onto the inner shell of a dewar, which has a thickness of about 1/16". He got the dewars surplus so I have no idea what alloy it might be. The fittings I'm going to weld on are 303 stainless, bought from a local welding shop that supplies stuff to the grape industry, which is very big in the area; they're rings with maybe a 3/16" wall, threaded 1" pipe. --I told him that if he wasn't in a hurry another pal of mine, who happes to be a mil-spec certified weldor, could do the parts for him but he's in a rush and said what I do would be good enough (yikes!). I'm planning to use that high nickel rod that Ernie turned me on to when last he visited (what is that stuff??). --The only thing that concerns me about the whole process is the intended use: one will be filled with liquid oxygen, the other with liquid propane. They'll be positioned in a bunker with their 1" i.d. pipes feeding to a rocket motor for a static test. Apparently he tests these things to destruction; i.e. around 30,000 rpm the motors tend to fly apart! The dewars are considered expendable, but I want to be sure they last long enough to be destroyed by rocket motor shrapnel, rather than by faulty welds. Any help/advice/etc appreciated!

Tig on dewar

Jul 21, 2005 22 Replies

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steamer 20 years ago

--Thanks; I'll pass that along to my friend; will remember to test next time he brings surplus dewars over here, too! I've got a feeling it won't be long...

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MetalHead 20 years ago

Hi Ed, Has your friend pressurized your Dewar yet? Please let us know how it worked when you know!

Curious, Bob

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steamer 20 years ago

--Will do. I think he's waiting for one more cryo valve he's got back-ordered B4 he can hook it all up at the proving grounds..

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