In the course of optimizing the turbo engine plumbing
I discovered that steel 37 deg JIC and AN are more or less
interchangeable.

There are some very useful devices in steel JIC that are not
available in AN.

Here are a few JPGs in an attempt to sort all this stuff out.

I recommend going with .035" thick wall soft steel or soft stainless
steel tubing in the 3/8 and 1/2 inch sizes where every possible as
it is much less likely to fatigue/crack than aluminum and it is a
lot cheaper than braided hose. It is also higher temperature
tolerant and a LOT LOT cheaper than Teflon lined braided hose.

AN-10 37 deg flare ID = .5 inches

AN-8 37 deg flare ID = .395 use for 1/2 inch OD steel tube.

AN-6 37 deg flare ID = .300 use for 3/8 inch OD steel tube.

Use the smooth 90 deg swivel fittings where ever fluid flow rate is high
as there will be less pressure drop through the fitting. In the case
of oil there will be a slight reduction in oil temperature as high
flow through a sharp 90 degree fitting will increase the oil
temperature as much as 10 degrees F.

You will need a tube bender and a 37 deg flaring tool. Especially
for the 1/2 inch steel tube. I modified a 45 deg flaring tool to
save a lot of money.

Once you get used to it the connections are also simpler than
braided hose and probably more reliable. JIC is used in all sorts of
heavy duty hydraulic equipment subject to much shock and vibration.
Support long runs with clips to something solid even tho the rotary
has much much less vibration than a piston engine.

The downside is a slight increase in weight but we are not building
airliners here with 1000's of fittings.

Paul Lamar

Hi Paul,

If you do not want to flare the tube, you could use Swageloc or Parker
fittings. I prefer the ferrules that Swageloc uses. You can snug the
fitting 2
flats to test fit and back it off to remove the tube. The flare job also
requires a sleeve between the nut and flare. If you do not use the
sleeve, the
tube will eventually break.

About tube benders; the cheaper benders have a tendency to leave a
small dip
in the tube where the bend starts. It is like the common exhaust
bends done a
a muffler shop. The inside area is reduced slightly. Swageloc makes
a good but
expensive bender that has rollers. Less stress on the tube and many
leave a
consistent bend that you can move the nut over like mandrel bent.

1/2" .035 stainless tube is good for 2600PSI. More than adequate.

Dale Davies

I just bought this die cast aluminum Imperial bender on Amazon for
about $60. Works great. No dips but a tiny bit of oval distortion.
This was 1/2 inch mild steel .035 wall. Ridgid makes a nice all
steel bender for one size tube for $100.

Paul Lamar

Hi Paul

If you elect to use JIC or AN are you going to use these ?
http://www.flaretite.com/

Bill Mc Donald

If I get a leak I might use something like that.

Paul Lamar


We used what we called FLARE SAVERS like these at Eastern flight
simulator hydraulic lines. Put them on first and not have to go back
and redo the connections, Virg