6-AN to PTFE Fitting Leak Question

[Junbug]

So as I'm assembling and testing my 6-AN to PTFE braided stainless fuel lines I keep getting minor leaks from the threaded side of the fittings (red arrows). All of the parts are Fragola brand, 6-AN fittings and PTFE braided line. I added a "exploded" fitting next to it so everyone can see what the internal parts are. The green arrow side has no leaks. The red arrow sides each have minor air bubbles leaking out when I pressurize (55 psi) and dunk the fitting under water. The leaks are all from the left-hand side of the right fitting (red arrow pointing at location.
https://thefactoryfiveforum.com/attachment.php?attachmentid=182058&d=1679772031

As another example, this is a 45 degree bend fitting so there is more separation between the side with the aluminum olive and the 6AN threaded side. No leaks on the green arrow side, but the red arrow side has minor leaks from its joint. Could it be that I just haven't torqued that side down tight enough? I hesitate because its aluminum and I don't want to strip/break anything. The olive's are single use and brand new but I believe the problem appears to be from the other side (red arrows). Would a solution be to use PTFE high temp thread sealant on the red arrow (threaded 6AN) side?
https://thefactoryfiveforum.com/attachment.php?attachmentid=182059&d=1679772031

I appreciate an tips or corrections!
Thanks,
-Bryan

[65 Cobra Dude]

I’ve used Fragola for a while and never had a leak there. I’m guessing as you stated that you did not tighten it enough? 11/16 open end wrench works and I’ve never stripped one. I crank them pretty tight.

Henry

[rich grsc]

The only reason for that to leak is it just needs a little more tightening with a proper wrench

[i.e.427]

Lubricate the threads and the cone portion of the AN fittings with motor oil. The aluminum doesn't like to tighten without lubrication.

Frank

[Papa]

I use these:

3AN-16AN Adjustable An Fitting Wrench for An Hose Fitting Adapters Ends Spanner Lightweight Aluminum Black https://a.co/d/d7fZ8kr

ICT Billet Aluminum 6AN Wrench 6 AN Hose Fitting 11/16 Wrench Fittings Thread Lightweight Ergonomic Compact Handle Designed & Manufactured in the USA 551454 https://a.co/d/8LaO9pA

[mmklaxer]

I’ve used Fragola for a while and never had a leak there. I’m guessing as you stated that you did not tighten it enough? 11/16 open end wrench works and I’ve never stripped one. I crank them pretty tight.

Henry

While I generally agree with “tighter is better,” my understanding is that -AN fittings should be hand tight plus 1.5 flats (1/4 turn). Oveetightening could cause leaks. Thoughts?

[rich grsc]

While I generally agree with “tighter is better,” my understanding is that -AN fittings should be hand tight plus 1.5 flats (1/4 turn). Oveetightening could cause leaks. Thoughts?
If it still leaks, then it needs just a bit more

[ej95Cobra]

Try Earl's conical seals. I ended up getting these for the same issue and they solved the problem.

https://www.jegs.com/i/Earls/361/169106/10002/-1

[mikeinatlanta]

Always use an anti-seize on aluminum AN fittings.
The way those fittings are made, the only possible source if making bubbles at the red arrow area is the sealing contact area. Inspect them both very closely, like 10x magnification. If no defects seen try a bit more torque, but not too much. If that fails to seal then the conical seals mentioned by ej95Cobra is your next step.

I've been making hoses and tubes for over 40 years and used to be a fan of Fragola. In fact, my entire roadster is plumbed with their product. Due to recent quality problems I've lost the faith in that brand and won't use them again.

EDIT: Good on you for actually testing your fittings. Most don't. That said: I do suggest testing at rated pressure for the hose. Not leaking isn't the same as resistant to blowing apart under pressure. I burned a car down once when a non-leaking connection came apart.

[Hoooper]

Assuming there isnt damage to the mating surfaces, if it leaks there it needs to be tighter. That said it is possible to overtighten AN fittings, in which case if that has happened there may not be a solution except replacement of both fittings. -6AN size really does not need to be very tight since its a small fitting, if you have to crank on it to get it tighter its probably already too tight

[rich grsc]

Assuming there isnt damage to the mating surfaces, if it leaks there it needs to be tighter. That said it is possible to overtighten AN fittings, in which case if that has happened there may not be a solution except replacement of both fittings. -6AN size really does not need to be very tight since its a small fitting, if you have to crank on it to get it tighter its probably already too tight
The thing is, how do you define tight. For a 70 yr old its is one thing, for a 30 yr old body builder it's something else. A little lube or a dab of anti-seize is a good suggestion.

[Windsor]

Would a solution be to use PTFE high temp thread sealant on the red arrow (threaded 6AN) side?
https://thefactoryfiveforum.com/attachment.php?attachmentid=182059&d=1679772031

No.

The seal isn't at the threads, it's at the taper on the end of the two halves.

Do what Frank said, a bit of lube/anti-seize on the tapers and threads and have at it again.

[efnfast]

I would only use Aeroquip fittings/hose, especially when it comes to fuel - Fragola made crap products 15yrs ago and on other forums I see they still make crap today.

[D Stand]

Looking at your photos, it does look like your test fittings have some scratches on the matting surface. You might want to inspect them for damage like others have stated. Also, it is hard to tell from the picture it looks like you might have 2 different degree tapered test fittings. I believe you can buy 37 degree and 45 degree AN fittings. If they are not the same, they will leak as well.

[mikeinatlanta]

Looking at your photos, it does look like your test fittings have some scratches on the matting surface. You might want to inspect them for damage like others have stated. Also, it is hard to tell from the picture it looks like you might have 2 different degree tapered test fittings. I believe you can buy 37 degree and 45 degree AN fittings. If they are not the same, they will leak as well.

All AN are 37 degree. Good idea to make sure your plugs are actually AN and don't have a 45 degree taper.

[mikeinatlanta]

I was putting a nitrous system on my Motus bike. All plumbing was Fragola. I was unable to get my -2 lines to pass high pressure leak test. After repeated attempts I contacted Fragola customer tech support. This was the first time in 40 years that I ever had a connection fail leak test.

Fragola asked if it would be ok for them to terminate the hoses for me and I agreed. The attached photo is my leak test of the line they put together. Keep in mind this is nitrous directly under an intake manifold about 12" away from my man parts. I called them back and learned that they only leak tested to 100psi. Blows my mind that they did a 100psi leak test for a 1,000 psi flammable gas system. Lost all faith at that point.

Contacted Summit and got hold of some high-level management. They were interested in my whole story along with much detail and many photos. They refunded 100% of everything Fragola I bought, even though cut, used, and not sellable.

All the replacement stuff was Aeroquip or Earls where Aeroquip didn't have what I needed. Also, Earls was the only hard line that was true seamless. The rest, although advertised as seamless, was in fact not seamless. Seems companies polish away the seam and call it seamless. AN tube seal on the inside of the line and need to be true seamless.

182184

[SourceLee]

I had a similar issue with Fragola. I also returned the fittings to Summit for a refund. I then had on online hose shop make me up custom hoses. Crimped hose fittings and tested well over 1000 psi before they left their shop. My hoses were being used for fuel and I couldn't afford for a leak.

[Papa]

I would only use Aeroquip fittings/hose, especially when it comes to fuel - Fragola made crap products 15yrs ago and on other forums I see they still make crap today.

The Aeroquip fittings I ordered from Summit are made by Fragola. Interestingly, they sell both brands. I wonder if the ones that are made for Aeroquip are any different than the ones sold as Fragola?

[mikeinatlanta]

The Aeroquip fittings I ordered from Summit are made by Fragola. Interestingly, they sell both brands. I wonder if the ones that are made for Aeroquip are any different than the ones sold as Fragola?

How do you know that Fragola made your Aeroquip fittings? Not saying you are wrong, but curious how you can tell.

[Papa]

They were stamped with the Fragola FPS markings

.https://thefactoryfiveforum.com/attachment.php?attachmentid=182426&d=1680458535

I may have mixed up Aeroquip with Aeromotive brands, though. It looks like it's Aeromotive that is using Fragola made fittings.

[mikeinatlanta]

They were stamped with the Fragola FPS markings

.https://thefactoryfiveforum.com/attachment.php?attachmentid=182426&d=1680458535

I may have mixed up Aeroquip with Aeromotive brands, though. It looks like it's Aeromotive that is using Fragola made fittings.

Thanks. That's what I was thinking too.