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txoval
Samba Member
Joined: January 23, 2004
Posts: 3552
Location: The Woodlands, TX
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 Posted: Mon Aug 19, 2013 8:05 pm Post subject: -AN fittings |
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Did a search for -AN fittings and nothing came up...this may be a dumb question, but id rather do it right the first time.
When connecting a male to female AN fitting do you need sealant? |
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Islandman
Samba Member
Joined: March 20, 2008
Posts: 671
Location: Clarksville, TN
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| Posted: Mon Aug 19, 2013 8:11 pm Post subject: |
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| Nope. |
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SRP1
Samba Member
Joined: January 06, 2007
Posts: 4340
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| Posted: Mon Aug 19, 2013 8:14 pm Post subject: |
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| X2 no you do not. It's the tapered flare that creates the seal, not the threads. |
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txoval
Samba Member
Joined: January 23, 2004
Posts: 3552
Location: The Woodlands, TX
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| Posted: Tue Aug 20, 2013 4:15 am Post subject: |
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| Thank you...just wanted to be sure before I took a chance of oil flying everywhere |
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theKbStockpiler
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Joined: July 07, 2012
Posts: 2316
Location: Rust Belt
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| Posted: Tue Aug 20, 2013 2:30 pm Post subject: |
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Old school people swear by putting some sort of lube on the flare part before tightening. Edit:I believe it helps the flare center its self. I always put something on every thread and use Teflon tape on something like that.
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jhoefer
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Joined: May 19, 2011
Posts: 987
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| Posted: Tue Aug 20, 2013 2:54 pm Post subject: |
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| theKbStockpiler wrote: |
| Old school people swear by putting some sort of lube on the flare part before tightening. Edit:I believe it helps the flare center its self. I always put something on every thread and use Teflon tape on something like that. |
Putting some lube on the shoulder of the nut can help prevent the tube or hose from twisting as you tighten the the fitting. Lube on the flare should be unnecessary.
Using teflon tape on the threads of an AN fitting is a bad idea. First, the threads are not a sealing surface in an AN fitting, a loose fitting will still leak even if the threads are perfectly sealed. Second, as the teflon tape squeezes out of the threads over time, the fitting can loosen and start to leak. |
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SRP1
Samba Member
Joined: January 06, 2007
Posts: 4340
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| Posted: Tue Aug 20, 2013 3:00 pm Post subject: |
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| jhoefer wrote: |
| theKbStockpiler wrote: |
| Old school people swear by putting some sort of lube on the flare part before tightening. Edit:I believe it helps the flare center its self. I always put something on every thread and use Teflon tape on something like that. |
Putting some lube on the shoulder of the nut can help prevent the tube or hose from twisting as you tighten the the fitting. Lube on the flare should be unnecessary.
Using teflon tape on the threads of an AN fitting is a bad idea. First, the threads are not a sealing surface in an AN fitting, a loose fitting will still leak even if the threads are perfectly sealed. Second, as the teflon tape squeezes out of the threads over time, the fitting can loosen and start to leak. |
I second the above. To add to that Teflon tape can be detrimental to some systems and applications should it get inside the line during assembly.
A small amount of lube on the threads, snug it up and you're good to go. |
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Hotrodvw
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Joined: July 06, 2004
Posts: 6327
Location: Orygun
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| Posted: Wed Aug 21, 2013 1:12 pm Post subject: |
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Lubricant on the threads vs. dry threads is the difference between wet and dry torque. The friction coefficient on the threads will require different torque settings at the nut. AN fittings don't require much torque at all. If you lube them, you'll need even less. If using Aluminum fittings, beware that the cone seat will flare out and cause a tight spinning nut if over tightened. It won't leak necessarily, but it will be a bastard to install and remove down the road.
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earthquake
Samba Member
Joined: January 10, 2008
Posts: 3984
Location: SANDY VALLEY, NEVADA
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| Posted: Thu Aug 22, 2013 1:25 pm Post subject: |
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I use a small dab of Loctite 567 pipe dope...
http://www.grainger.com/Grainger/LOCTITE-Pipe-Sealant-5A236?Pid=search
Just I'm not screwing the fitting in dry. [don't buy it at Grainger's, it way to expensive.]
Casey
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Hotrodvw
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Joined: July 06, 2004
Posts: 6327
Location: Orygun
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| Posted: Thu Aug 22, 2013 1:55 pm Post subject: |
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Thread sealant is pointless.
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78x94 with IDA's....oober fun
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captain flathead
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Joined: July 23, 2013
Posts: 40
Location: Lakeland Fl
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| Posted: Thu Aug 22, 2013 3:12 pm Post subject: |
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| Lube on threads will sometimes cause an over tightened situation with with a low torque value. Put never seize on a wheel stud and torque to 100 ft lb and see what happens. The right lube could cause the fastener to fail at low torque values. |
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captain flathead
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Joined: July 23, 2013
Posts: 40
Location: Lakeland Fl
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| Posted: Thu Aug 22, 2013 3:15 pm Post subject: |
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| Never mind, Hotrodvw already said it. |
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bugguy1967
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Joined: January 16, 2008
Posts: 4341
Location: Los Angeles, CA 90016
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| Posted: Fri Aug 23, 2013 6:37 pm Post subject: |
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I'm in aerospace and we use Earl's brand AN fittings for our R&D. We use some kind of oil on the flare and oil on the threads as well if it's steel on aluminum. Over time in the field, we've found that the two fittings will seize together from corrosion if they're steel on metal.
We use compressor oil because we deal with A/C systems mostly.
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Hotrodvw
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Joined: July 06, 2004
Posts: 6327
Location: Orygun
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| Posted: Fri Aug 23, 2013 6:39 pm Post subject: |
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Ironically, their designed to be a metal to metal seat.
Aluminum on aluminum, I can see the corrosion.
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78x94 with IDA's....oober fun
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bugguy1967
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Joined: January 16, 2008
Posts: 4341
Location: Los Angeles, CA 90016
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| Posted: Fri Aug 23, 2013 6:57 pm Post subject: |
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It's actually rust I believe that was seizing our dissimilar metal fittings and not aluminum corrosion. Our steel flares are zinc plated. I hear that Stainless on aluminum is even worse if corrosion builds up.
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Derek Cobb
Annoying
Joined: March 11, 2004
Posts: 2565
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| Posted: Fri Aug 23, 2013 7:06 pm Post subject: |
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| I've asked this question before and never gotten an answer, but I'll try here. What is the correct torque for aluminum AN fittings? Nobody I've ever asked knows. |
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SRP1
Samba Member
Joined: January 06, 2007
Posts: 4340
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| Posted: Fri Aug 23, 2013 7:38 pm Post subject: |
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| Derek Cobb wrote: |
| I've asked this question before and never gotten an answer, but I'll try here. What is the correct torque for aluminum AN fittings? Nobody I've ever asked knows. |
These are the maximum torque values in ft lbs with lightly oiled threads and flare surface. Regardless of the oil or not to oil comments above oiling the threads and flare surface prevents distortion while tightening. Again these are the maximum values.
-3 =8.75ft lbs.
-4 =11.5
-6 =16.5
-8 =29
-10=35
-12=45
-16=70 |
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Islandman
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Joined: March 20, 2008
Posts: 671
Location: Clarksville, TN
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| Posted: Fri Aug 23, 2013 7:41 pm Post subject: |
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Best places to search are aviation maintenance websites. From my A&P books for the most common aluminum sizes we use:
-4 40 to 60 in lbs
-6 75 to 125 in lbs
-8 150 to 250 in lbs
The old school trick for any AN fitting is to snug it, back it off, snug it again, then tighten an additional flat. This usually seats the flare and gets you within torque range. (For the record, if its a flight critical line, I go get a torque wrench  ) |
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