My entire LOX/kerosene test stand uses Swagelok brass and stainless NPT
fittings, mostly 3/8 and 1/2 inch tube sizes. I clean them as you would
normally for oxygen use and use a couple wraps of PTFE tape on the NPT
ends. They are generally very reliable and you can get them much
cheaper on eBay (new) if you look around a bit. Occasionally I've had a
leak at the NPT end, usually when the mating part has crappy female
threads. The tube nut ends only leak when I forget to tighten them down
after maintenance.
-Bob
On 3/27/20 8:01 PM, Jonathan Goff wrote:
I can't remember if we used Swageloks for much while I was at Masten, but here at Altius we've used them a lot for LN2 where we're doing fairly sensitive vacuum leak testing of various cryogenic couplers, swivels, etc.
~Jon
On Fri, Mar 27, 2020 at 6:24 PM Anthony Cesaroni <anthony@xxxxxxxxxxx <mailto:anthony@xxxxxxxxxxx>> wrote:
We have used Swagelok extensively with LOX and HTP for small
diameters. I can’t think of any examples where we used NPT
fittings with sealants of any kind with those oxidizers. There are
a few examples where test points were sealed with PTFE tape and
NPT fittings but nothing for delivery come to mind. There are some
rocket plumbers on this list that do this more routinely than I do
nowadays.
Anthony J. Cesaroni
President/CEO
Cesaroni Technology/Cesaroni Aerospace
http://www.cesaronitech.com/
(941) 360-3100 x101 Sarasota
(905) 887-2370 x222 Toronto
*From:* arocket-bounce@xxxxxxxxxxxxx
<mailto:arocket-bounce@xxxxxxxxxxxxx>
<arocket-bounce@xxxxxxxxxxxxx
<mailto:arocket-bounce@xxxxxxxxxxxxx>> *On Behalf Of *Rick Wills
*Sent:* Friday, March 27, 2020 8:04 PM
*To:* arocket@xxxxxxxxxxxxx <mailto:arocket@xxxxxxxxxxxxx>
*Subject:* [AR] Swagelok and LOX
Hi
Has anyone on the list used Swagelok compression fittings in
service with LOX (3/4 or 1 in)? I’ve used AN (37 deg flare) and
NPT fittings successfully for LOX. NPT fittings are wrapped with
PTFE tape. My entire LOX side on my test stand is all AN expect
for the NPT adapters used on the main LOX valve and LOX load
valve. Any LOX experience with any other brand of compression
fittings (Parker, etc). I’m looking at changing the stand
plumbing and am considering Swagelok. Check out our Facebook page
https://www.facebook.com/midwestpropulsiongroup to see the stand
in action.
The Army missile spec forbids NPT fittings. Most likely reason is
they could vibrate loose. I’ve seem amateur liquid systems
using NPT fittings successfully. Any advice would be
appreciated. On my first test stand, I welded the NPT fittings
together. It worked but looked pretty bad. An A&P I know
suggested safety wiring the NPTs so they would come loose. That
is a lot of work.
I’m lucky. My outbuilding is also my rocket workshop. When I
want to escape I run out back for a few hours. Thanks and
everyone take care.
Be Safe,
Rick Wills
Huber Heights, Ohio