Swagelok is also very nice in supporting student projects. I am involved
in the ARIS project ( https://aris-space.ch/ , rockets for the
spaceport America cup, which had been canceled for this year :-( ) and
Swagelok supports us with all the valves, fittings, tubing's etc for the
test stand
Bruno
Am 29.03.2020 um 05:35 schrieb Michael Clive:
To continue on Ben's vibe:
Swagelok is the best brand for compression type fittings. Parker etc
are slightly worse in terms of quality control, from my experience.
Surface finishes are not as nice, plating is worse. Swagelok also is
expensive but very responsive and kind. Their sales reps will do
/anything /for you, if you buy enough. If not, Ebay will get you
everything you need.
NEVER mix and match a parker fitting to a swage body, or a parker body
to a swage fitting. They claim they are interchangeable, but they can
have minor variations in geometry and thread form that can gall stuff
up or generally make your day worse.
McMaster compression fittings are Parkers. They are okay, but nothing
beats the real thing.
Swages above 3/4" become a huge pain in the ass and you need a
hydraulic preswaging tool and a second bank account for fittings at or
above 1".
Swages are excellent, but you need to be really experienced with them.
There are no torque specs. /there are *no *torque specs. /You torque
them down until a certain displacement is met. You then always reseat
them with the tiniest bit more oomf. If you don't have a calibrated
arm, you will overswage if you ever reinstall, and it will leak, and
you will have to pull the tube and replace it. There is no spec for
this, it's just a feeling you develop after doing a few hundred of them.
Big super obvious one that bit me when I was green: Don't swage a
brass fitting on a stainless tube, or a stainless fitting on an inco
tube. You can swage stainless on brass or inco on stainless, but
always move down the strength chain. Why? The brass just won't bite
the steel tube and it will 'splode. I had it happen on a 1/2" air line
and it was loud and very embarrassing.
And yeah, if you are a rocket person on this list and are working at
20ksi, good job on gettiing your phase 3 in-space propulsion contract
from $GOVBUCKS. Looking forward to your launch.
My post-apocalypse profession is going to be as a plumber.
On Sat, Mar 28, 2020 at 5:34 PM Ben Brockert <wikkit@xxxxxxxxx
<mailto:wikkit@xxxxxxxxx>> wrote:
Ok, I'll backtrack to say that for 1/4" and smaller, higher pressures
are likely to be fine *if* you are swaging correctly and using normal
hardness tubing. The forces are not as crazy. But still, the advantage
of "cone and thread" and AN fittings is that if they are not tightened
they just leak, rather than having the tube go shooting out of the
fitting like an un- or under-swaged tube.
The Swagelok FK medium pressure system in half inch and larger with
thicker and harder tubing is trouble waiting to happen. I've seen it
go off twice, it's very violent and loud. Fortunately in neither case
was anyone injured.
And for folks new to this, "medium pressure" and "high pressure" are
terms of art for specific fitting systems, where medium is up to
20,000 psi and high is up to 60,000. Most rocketeers will never get
into medium pressure, and the highest you'll ever see is a 6000 psi
bottle that can be worked with using normal AN fittings.
And "Swagelok" is a company and a brand, but generally people use it
specifically to mean two ferrule compression fittings in the
Swagelok/Yor-Lok/A-lok line.
On Sat, Mar 28, 2020 at 2:55 PM Michael Clive <zeinin@xxxxxxxxx
<mailto:zeinin@xxxxxxxxx>> wrote:
>
> However, to follow up with Ben:
>
> Medium, high pressure and UHP fittings are PHENOMENAL. If you do
them right (cone-and-thread fittings), they never, ever leak. And
they are very repeatable. Not good for vibe, but for test stands,
they are great! Maximator makes the best tools for them. Peter
Duffy at High Pressure Technologies is about the best sales guy
you will ever talk to, and he will sell you anything you need for
10k+ work. Tubes, fittings, valves, anything.
> I agree with Ben on not using bite type fittings EVER for above
10k work. Cone on thread is the best!
>
> On Fri, Mar 27, 2020 at 8:55 PM Ben Brockert <wikkit@xxxxxxxxx
<mailto:wikkit@xxxxxxxxx>> wrote:
>>
>> I kinda hate Swagelok fittings over 3/4". They just suck to get
leak
>> tight. 1/4" and 1/8" swagelok fittings are great, they are
perfectly
>> suited to the task. Work fine with LOX. Follow the assembly
>> instructions! Buy a preswaging die if you use them a lot. 1/4"
>> swagelok fittings are the easiest way to build weird assemblies
like
>> temperature/pressure ports in pipes or coaxial heat exchangers. And
>> work well for things like gauge boxes, test benches, etc.
They're also
>> called "instrumentation fittings" and that is a good description of
>> what they are good for.
>>
>> They are not great with vibe. Well suited to ground equipment,
less so
>> to flight.
>>
>> If you use them with peroxide the nuts should be processed in acid
>> first. There is silver plating on the threads to act as
antiseize, if
>> you have a peroxide leak through a silver fitting then the fitting
>> ends up getting hot and the leak escalates itself to asking to
speak
>> to the manager. Once you strip the silver antiseize off, then
you need
>> to replace it with something else on assembly, like krytox.
>>
>> Any use of any swage fitting over 3000 psi is a mistake. Go
straight
>> from AN to cone and thread. Do not believe the marketing around
medium
>> pressure swage fittings. When a 5000 psi fitting decides to
dissociate
>> next to you, the best case is a startling.
>>
>> Ben
>>
>> On Fri, Mar 27, 2020 at 5:05 PM Rick Wills <willsrw@xxxxxxxxx
<mailto:willsrw@xxxxxxxxx>> wrote:
>> >
>> > 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
>> >
>> >
>>