Tips for flaring for AN fittings.

[Samckitt]

Is there any tips, or instructions anywhere for doing this to make sure I don't have any leaks?

Or is it as simple as cutting the tubing, flaring it & good to go?

Thanks,

[parsonsj]

These may be obvious, so apologies in advance if you already knew this:

1. If using stainless, watch for work hardening. Don't use a tubing cutter, use a saw of some sort that generates chips. I use a bandsaw.
2. Get the cut square. I use a belt sander to get it "just so".
3. Use grease on the expanding die, so there is less tendancy for the tube to slide away rather than expand.
4. The flare should be big enough to just allow the nut to slip over it. It is a common mistake to not make the flare "flared" enough, which leads to leaks.
5. Debur the cut. I use a chamfer cutter in a drill for the inside, and the belt sander or a file for the outside. Don't take too much material off ... remember this exact area is where the metal gets stretched the most.
6. Don't forget to put the sleeve and nut on the tube before flaring! Or you'll be very disappointed. :)

jp

[Marktat]

Don't forget AN flares need to be 37 degrees, as a opposed to standard automotive 45 degrees.

You probably know this but just wanted to be sure.

[Samckitt]

I have a Ridgid 37 degree flaring too. This thing works great. I highly recommend it if anyone is debating on which one to get. I got it on Ebay.

Can I use a tubing cutter if I am not using stainless?

What about deburring it after cutting it? Need to do it or not?

Thanks

[parsonsj]

If you're just using steel tubing, then work hardening is less of a problem. Perhaps a tubing cutter will be ok, but I've never done it that way. The advantage of the tubing cutter is square cuts, so it may work better than cut and sand for steel tube.

Good question about de-burring. I use an 82 degree chamfer cutter in a drill to debur the inside of the tube, and a quick pass on my belt sander to get rid of the burrs on the outside. Then I blow the tubes clean with compressed air before flaring. I added that info to my post above.

jp

[silver69camaro]

We use stainless tubing from Classic Tube, and we never have any problems with work hardening. We just use it like regular steel tube.

[parsonsj]

We use stainless tubing from Classic Tube, and we never have any problems with work hardening. We just use it like regular steel tube.Matt, can you define what you mean by "use"? Are you saying you cut stainless tube with tubing cutters?

jp

[Jim Nilsen]

On the tubing I got from Classic Tube I was able to use tubing cutters with no problems that I can see. I am using a Ridgid flairing tool which is a lot better than the cheaper tools.
Maybe when I do the 3/16 tubes it will be easier and better to cut it but the 3/8 and 1/2 has been very easy to work with.

Jim Nilsen

[parsonsj]

On the tubing I got from Classic Tube I was able to use tubing cutters with no problems that I can seeHuh. Good to know, because one can sure get a better, squarer cut with a tubing cutter.

jp

[BonzoHansen]

Never used SS lines, but for steel or alminum lines, I've had no problems with a tubing cutter. I got a deburring tool form home depot for the inside and I use emory paper on the outside, maybe a slight bevel on the outside on the grinding wheel. I use 3 in 1 or other oil on the tube when i am flaring it. No issues with 45* double flares.

Yes, put the nuts on first.... :)

[Kenova]

I've only AN flared aluminum, but the Rigid tool is just the Cat's A$$.



4. The flare should be big enough to just allow the nut to slip over it. It is a common mistake to not make the flare "flared" enough, which leads to leaks.
I found it almost easier to make the flare a little too big and then trim it down with a fine file. With enough practice a person could easily make the flare the perfect size each time.



6. Don't forget to put the sleeve and nut on the tube before flaring! Or you'll be very disappointed. :)
jp
Forgetting to put the nut and sleeve on before flaring will produce a perfect flare every time. At least that has been my experience.
Ken

[Samckitt]

Is there a certain type of steel line that should be used? Or do all of them have the seam where it is formed together? Any problems with it sealing on this seam in the flared area?

[Twin_Turbo]

you can only single flare seamless tubing, no n seamless has to be double flared to turn the smooth otuside inwards to create a perfect sealing surface.

I've double flared alumium, steel and single flared seamless stainless, all it takes is a high quality flaring tool.

Also, never use a tubing cutter on stainless lines, you will work harden the cut area and destroy the flaring cone in a hurry.

[silver69camaro]

Also, never use a tubing cutter on stainless lines, you will work harden the cut area and destroy the flaring cone in a hurry.

Read above. Stainless lines from Classic Tube do not have this problem. Others may be OK too, but I've only used it from Classic and Williams Oil and Filter Service in Tacoma, WA. Both work great with standard tubing cutters and double flare tools.

I'm going to go out on a limb and say this...45* flares do not leak on 37* fittings. Many, many pro builders use 45* on AN fittings...I know, I know, you shouldn't do it. But it does work.

I'm putting my flamesuit on as we speak.

[Samckitt]

So what I am hearing is with a seamed tubing, I will have leaking problems with a single flare 37 degree flaring tool....? It is a good quality flaring tool, it is a ridgid brand tool.
Thanks.

[BonzoHansen]

So what I am hearing is with a seamed tubing, I will have leaking problems with a single flare 37 degree flaring tool....? It is a good quality flaring tool, it is a ridgid brand tool.
Thanks.
It is not the tool. It is the seam.

[Twin_Turbo]

exactly.

Sam, does your tool do double flares? Is it capable of stainless? Most aren't. A tool capable of doing stainless is very expensive, like the imperial 400F, I have 2 papco rotomasters and they do an awesome job, however they were not cheap.

[parsonsj]

Stainless lines from Classic Tube do not have this problem <edit: we're talking about work hardening>. Others may be OK too, but I've only used it from Classic and Williams Oil and Filter Service in Tacoma, WA. Both work great with standard tubing cutters and double flare tools.Let's be careful, please. I understand that many people are successful using tubing cutters on stainless steel tube. No leaks, no muss, no fuss. That's cool, and a useful data point.

However, it is true that austenitic (304, 316, 18/8, etc.) stainless steel as a material (no matter the supplier) work hardens much more readily than mild steel. That's a property of the material itself, not the supplier. I'm guessing the ss tube that has the best luck is thoroughly annealed (sometimes advertised as "triple annealed") prior to cutting.

The reason I mentioned cutting ss tube with something that generates chips is to enhance the possibility that the cutting tool will get under the work hardened surface as it cuts, leaving a still annealed end available for flaring. Using a tubing cutter is obviously less desirable from the viewpoint of having the most ductile material possible for the flaring operation.

On the other hand, it could be argued that the advantage of a perfect 90 degree cut (as is usually achieved with a tubing cutter) is worth the work hardening disadvantage.

Hope that makes sense.

jp

[Twin_Turbo]

I have no problem getting the end perfectly straight, I use the clamping blocks from the flaring tool, insert the pipe and check if it's completely flush, I file to correct. Works every time.

[Samckitt]

Twin-turbo - No the tool cannot make double or inverted flares. Not sure if it will do stainless, I don't see why not. You say a tool that does stainless is very expensive, what do you consider expensive?

[Rick Dorion]

In my pursuit of spending too much money on tools I use rarely, I purchased a hydraulic flaring tool. It improved my consistency alot :)

[parsonsj]

I use the clamping blocks from the flaring tool, insert the pipe and check if it's completely flush, I file to correct. Good idea ... I hadn't thought of that. I've been using a bench belt sander set up with a machinist's square. I don't have any problem getting servicable square cuts either.

jp

[parsonsj]

In my pursuit of spending too much money on tools I use rarelyLOL! Ain't that the truth! I've got a complete set of Ridgid tube benders that have made 10 bends apiece, max.

jp

[Twin_Turbo]

You will find out soon enough if it does stainless, if the flare cone cracks it's not suited. Check out the imperial eastman 400F flaring tool. Its more than a couple of hundred bucks easily.

[Karch]

I sold high-end tubing for a few years, and I will say that while seamless tubing is, for the most part, superior, you can get very, very high quality welded and drawn (seamed) tubing.

The cheapest tubing I sold was made from stainless, and it went up from there (titanium, inconel, berrylium copper, tantalum, nitinol, etc). The key to welded and drawn is laser welding, lots of precise annealing, and very precise drawing.

If done correctly, you need high-end equipment to find where the weld was, and even then it looked pretty homogeneous.

Also, the key to flaring stainless is correctly mentioned above. Start with fully annealed material and do not put much cold work into the location where the flare will be.

[ItsA68]

a quick check of the Ridgid tool web site says that their 37 degree flaring tool is for SAE flares, and not the JIC/AN that we use.....are the flares compatible? I found the Imperial flaringing tool, but it was more than $300, and the Ridgid was only $100, but it does SAE 37 degree....is there any difference? What Ridgid tool part number are you guys using? I'm about to need to do some flaring, and must get the right tool.

thanks,

~~fred

[Twin_Turbo]

SAE = 45 degree, JIC-SAE/AN use 37 degree flares. If it's a 37 deg. flare tool it'll work for JIC & AN (the only difference is the thread profile and quality, AN is higher quality aircraft stuff)

[silver69camaro]

As I posted previously, a 37* fitting will seal on a 45* flare. It's not technically correct, but it sure works.

[Twin_Turbo]

The sole purpose of the 37 degree flare taper is to provide a larger sealing surface for a given tube size. using a 45 degree flare and hoping that the greatly reduced contact area will seal is just foolish. If you don't have the tools to do proper an flares stick with the 45 degree stuff.

Before you know it people will be using a 45 degree flared tube to connect an fittings in a brake application. Would you still stand by your claim that it works? Just stating it seals.. ok, but to what pressure?

[silver69camaro]

Before you know it people will be using a 45 degree flared tube to connect an fittings in a brake application. Would you still stand by your claim that it works? Just stating it seals.. ok, but to what pressure?

Little do you know that people have been doing that for decades. Hey, I said it wasn't correct. Don't shoot the messenger.

And yes, I stand by my statement that it works. Even in a hydroboosted setup. The reason why it works is because the flare re-forms itself to the 45* fitting when using a tube nut (and that is the key, use a tube nut). But like I said, it isn't technically correct. And FYI, I use a hydraulic flaring tool with a custom 37* cone.

[Twin_Turbo]

you must mean tube sleeve, as in using a 37 degree taper tube sleeve and the tube nut (which is straight, the taper is in the sleeve only) and by tightening these you conform the 45 degree flare to the 37 degree taper so it seals up? I can see how that would work (somwhat) on aluminium and maybe steel lines but on stainless already being work hardened by the flaring process....

I believe in doing things right so in my book, if you want to use an hardware invest in a proper 37 degree flare tool, especially when working on brake lines.

[Samckitt]

OK dumb question: Why was 37 degrees decided on for Army/Navy fittings. I assume it seals better than 45 degrees & if so, how?

[Twin_Turbo]

I said that above, 37 degree flares have a much larger sealing surface for the same ID.

[Samckitt]

Sorry Twin, I must have missed it. I wonder why 37 though, why not 35, or 30? Strange.

[parsonsj]

My limited research has found two assertions. Can't call them facts, since they are unattributed.
1. AN fittings were deliberately different from the traditional 45 degree so that automotive and industrial fittings wouldn't work, thereby ensuring correct military stuff was used. That seems weak, but is what Goodyear and Gates have to say (in identical wording, so they both got that fact or myth from somewhere else).
2. 37 degrees is the highest degree that steel can be safely flared without the material having splitting and fatigue problems. 45 degree flares are fine for soft metals like copper, but steel wasn't reliable with that much flare. 37 degrees was the biggest reliable flare for steel.

Which is true? I don't know. I found no reference to larger sealing area, though that could be the case. YMMV.

jp

[Twin_Turbo]

Just think of it, or draw it out. Take a tube w/ a similar OD and ID and draw a 45 degree flare and a 37 degree flare, it's pretty obvious which has the larger sealing surface....and since there's more surface area to a 37 degree flare, this larger sealing surface has a much higher pressure rating than ordinary flares. This is the reason why a similar (same apart from thread profile, tightness in thread interlocking and material quality standards) JIC system is used in hydraulic systems. J?IC and AN hardware can be mixed (although jic is not aircraft quality and therefore not certified) JIC is the industrial variant of the Airforce/Navy AN system.

I think it was parker that developed the 37 degree fitting originally. Initially they did have a 30 degree fitting but thayt was replaced witha 37 degree one. This was before wwII I think, I read that somewhere..it may be wrong though.

[Samckitt]

I haven't looked that close to the actual flare, but I assume it is flared like version A in the attached image.

[parsonsj]

No, it's B.

Right: AN was first developed during the rampup for WWII. At that time the military was having a hard time getting all their sub-contractors to work together. So the AN system was designed as a standard.

As far as the greater surface area from less flaring, I understand what you are trying to say. But look at Scott's drawing. Using that drawing, and knowing that AN is version B, you can see that a 45 degree flare will have more surface area, not less.
jp

[Bow Tie 67]

Is there an easy way to tell what angle flare you need?

The car I bought had Baer calipers with 90* fittings attached, when I get home I'll look for markings on them.

[parsonsj]

Now, you could say that the nut constrains the outer diameter of the flare, so that the 37 degree flare is deeper than a 45 degree flare and thereby has more surface area. I get that.

Then I'll say that more surface area isn't necessarily better. Uniform and concentric is better, which is why Matt's 45 degree observations are true: most of the time a 45 degree flare on a 37 degree mating surface works fine, even with pressure at 1000+ psi. In the end, it is the quality of the flare, not necessarily the size.

I tell my wife that all the time. :)

jp

[parsonsj]

Is there an easy way to tell what angle flare you need? Sure: a 45 degree flare will have a 90 degree end (45+45). The AN will have a 74 degree end. You can see that pretty easily.

Or you could call Baer and ask.

jp

[Samckitt]

I added some dimentions & added a third hole to show the comparison.
All holes are 3/8" & all countersink diameters are .6 (pulled that number from my butt)

You can see in version B that the surface area of the flare is larger than that of all the others.

[parsonsj]

Right. When you constrain the outer diameter of the flare, the deeper the flare, the more surface area there is.

And that might be the reason. I just can't find a source for it.

Which brings us back to Scot's question a few posts back: it that's the rationale, why stop at 37? Why not 30 or 20 or 15?

Here's another consideration: the deeper the flare, the less tolerant the hard line will be to off-center sealing. I'd guess AN flared hardlines have more problems when the tube isn't lined up exactly.

jp

[silver69camaro]

In the end, it is the quality of the flare, not necessarily the size.

I tell my wife that all the time. :)

jp

Amen brother! :smoke:

[Twin_Turbo]

Now, you could say that the nut constrains the outer diameter of the flare, so that the 37 degree flare is deeper than a 45 degree flare and thereby has more surface area. I get that.

Then I'll say that more surface area isn't necessarily better. Uniform and concentric is better, which is why Matt's 45 degree observations are true: most of the time a 45 degree flare on a 37 degree mating surface works fine, even with pressure at 1000+ psi. In the end, it is the quality of the flare, not necessarily the size.

I tell my wife that all the time. :)

jp

And that is why I advised to use a high quality 37 degree flaring tool, and they don't come cheap. i have a mil spec tool for doing the an flares, never had one leak ever.

[parsonsj]

i have a mil spec tool for doing the an flares, never had one leak ever.My Imperial flaring tool is worn out ... got a recommendation for a good one?

jp

[Twin_Turbo]

imperial eastman 400F

You must have made a lot of flares for it to be worn out. You can get just a new flare cone though and save a bundle.

[parsonsj]

The cone itself is ok. The threads are galled and the cone is "sticky" on the engagement shaft. It takes too much effort to flare stainless.

jp