[AR] Re: Astraseals vs. welding
- From: Paul Mueller <paul.mueller.iii@xxxxxxxxx>
- To: arocket@xxxxxxxxxxxxx
- Date: Mon, 17 Feb 2014 13:29:11 -0700
Commercial LOX systems use a lot of pipe threads (with proper sealant).
Since frequent disconnection/reconnection or swivel capability don't seem
to be an issue if you're thinking about welding it, then I would go with
pipe thread. Teflon tape, Loctite Thread Sealant for Oxygen Compatible
Systems (
http://www.henkelna.com/us/content_data/184197_LT5549_OxygenSystemsSS.pdf)
, could work depending on pressures, etc.
Paul M
On Mon, Feb 17, 2014 at 12:51 PM, Robert Watzlavick
<rocket@xxxxxxxxxxxxxx>wrote:
> I was considering a Miller Syncrowave 200 (used) or the new 210. Even if
> it takes me a year or more to get up to speed, I figure it will be worth
> it. Of course a non-welded design would be preferable, hence the question
> about Astraseals.
>
> -Bon
>
> On Feb 17, 2014, at 13:31, "Monroe L. King Jr." <monroe@xxxxxxxxxxxxxxxxxx>
> wrote:
>
> > Well welding is not something you just pick up esp TIG. Perhaps if your
> > gifted but... A proper TIG welder is also expensive these new cheap
> > TIG's are just that cheap. If you buy a TIG get a used a Miller,easb it
> > takes at least 250 amps for alum done right and if you have a TIG you
> > will be disappointed if you cant weld with it when you want too. 300
> > amps is better.
> >
> > TIG is more like OXY/acetylene welding than arc welding. It's an art
> > either way. Not saying you cant do it but now your learning a new skill.
> > For a liquid rocket guy it is a VALUABLE skill indeed.
> >
> > People will laugh but for X-Ray welds you can make your own X-Ray from
> > an old tube. Read in Strong Amateur Scientist. Works very well for that.
> >
> > If you wanna try TIG for steel only I've had good luck with a ford 130
> > amp alternator and just buy an aircooled Tig handle and cable and a CO2
> > regulator off ebay. You can look the rest up yourself, it's cheaper to
> > try that way and the results are as good or better than a cheap Chinese
> > TIG box.
> >
> >
> >
> >
> >
> >> -------- Original Message --------
> >> Subject: [AR] Astraseals vs. welding
> >> From: Robert Watzlavick <rocket@xxxxxxxxxxxxxx>
> >> Date: Mon, February 17, 2014 11:54 am
> >> To: arocket@xxxxxxxxxxxxx
> >>
> >>
> >> I'm debating on using Creavey Astraseals to fix my tank design that
> leaked when cold tested with LN2. The 2-246 o-ring should work for the fuel
> tank but I need a different approach for the LOX tank. For those that have
> used the Astraseals, do they work as advertised? Also, are they reusable?
> I got a quote this morning of $236/ea in small quantities. If they really
> work, then it's worth it. Otherwise I was considering welding the tank tube
> yo the end caps/couplers. I don't have any welding experience (yet) but it
> seems like cracking and strength in the HAZ are the main issues. I expect
> post-weld heat treat at a local shop would restore the strength but the
> potential for cracks is what worries me the most. I can hydro test and
> probably do dye penetrant myself but I suspect X-rays are cost prohibitive
> for amateur work. I wanted to get a TIG welder anyway for other parts of
> the airframe anyway but I'm not sure i can safely make the tanks.
> >>
> >> My original design worked great except for the leaks- is there anything
> else (brazing, etc.) that might work to seal the gap between two concentric
> tubes? I thought about making the inner coupler out of SS304 so when cold,
> it would turn into an interference fit since the outer tube of 6061 would
> shrink faster. That plus a tighter squeeze on the o-ring might work.
> >>
> >> Any advice or experience would be appreciated.
> >>
> >> -Bob
> >
> >
>
>
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