Guest TegRacer324 Posted August 9, 2006 Share Posted August 9, 2006 I'm in the process of plumbing my fuel cell and I was wondering should I be using teflon tape or something else to make sure the connections don't leak or should I just be leaving them bare? Quote Link to comment Share on other sites More sharing options...
johnc Posted August 9, 2006 Share Posted August 9, 2006 No on the AN fittings. Yes on the NPT side of adapters that let you connect AN fittings to objects that have non-AN threaded openings. Quote Link to comment Share on other sites More sharing options...
2126 Posted August 9, 2006 Share Posted August 9, 2006 Typically teflon tape is not recommended fpr fuel system fittings. Why, because if allowed to enter into the fuel system it can clog things up.....like pumps, regulators, jets......! If you are using flared AN fittings, they require no sealant. They seal via the flares. The threads on a flared fitting do not create the seal. However, if you are installing a NPT fitting it can be used provide you don't apply the tape to the first three thread (an aircraft requirement IIRC). This practice is some insurance that the teflon tape doesn't get into the working system. A good alternative to the teflon tape is teflon pipe dope but, the same applies about not allowing it to get into the working system. Hope this clears the air a bit! Tom Quote Link to comment Share on other sites More sharing options...
Guest TegRacer324 Posted August 9, 2006 Share Posted August 9, 2006 Alright thanks a lot for the help guys. Quote Link to comment Share on other sites More sharing options...
datsunan Posted August 9, 2006 Share Posted August 9, 2006 I have had teflon in my inj. and it caused me a hell of a lot of trouble untill I found it. I used a yellow teflon that was made for use with gas, you might want to get some I don't know if all teflon tape is good for gasoline. Quote Link to comment Share on other sites More sharing options...
TimZ Posted August 10, 2006 Share Posted August 10, 2006 No on the AN fittings. Yes on the NPT side of adapters that let you connect AN fittings to objects that have non-AN threaded openings. Agreed. As others have mentioned the AN side will seal itself. However, you should be sure to use some sort of lubricant on the AN threads to keep the aluminum from galling. I generally use 3-in-1 oil, others use a few drops of motor oil - just be sure you use something suitable for aluminum. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted August 10, 2006 Share Posted August 10, 2006 Instead of using tape how about PST on the NPT side of the fitting? Seems like it might be less likely to clog something in the fuel system, be it injector or pump or filter... Quote Link to comment Share on other sites More sharing options...
2126 Posted August 10, 2006 Share Posted August 10, 2006 Instead of using tape how about PST on the NPT side of the fitting? Seems like it might be less likely to clog something in the fuel system, be it injector or pump or filter... I think I hear an echo Jon! Quote Link to comment Share on other sites More sharing options...
Guest TegRacer324 Posted August 11, 2006 Share Posted August 11, 2006 Eh crap my return line is leaking at the sump. Looks like I'll try putting some oil on the threads and tightening them up again. Hopefully that stops it. Quote Link to comment Share on other sites More sharing options...
Chemicalblue Posted August 16, 2007 Share Posted August 16, 2007 Sorry to bring this one back, but the leak is back and this is the only thread that covers the topic of thread sealant on the fuel rail(on the google search). Is there now a consensus on what works long term? I can tell you that white thread tape does not and red locktite doesn't las long either. What is PST? Quote Link to comment Share on other sites More sharing options...
mark Posted August 16, 2007 Share Posted August 16, 2007 If you have an NPT type fitting that is leaking, you have a few options 1 just try tightening the fitting. 2 take it apart, clean and inspect the threads on both parts, use teflon tape on the male threads, two wraps of the tape in the direction that will not unwind the tape as the fitting is inserted. If applied correctly, it will not get in the fuel system. The tape ends up inbetween the threads and stays there. 3 replace the fittings. good luck Quote Link to comment Share on other sites More sharing options...
Chemicalblue Posted August 16, 2007 Share Posted August 16, 2007 Tnx Its been my experience that Teflon tape no matter how its applied does not work for long exposed to fuel, not to mention its not recommended for use in or around fuel (probably because it dissolves). I guess we are back to the question what does? Quote Link to comment Share on other sites More sharing options...
mark Posted August 16, 2007 Share Posted August 16, 2007 Tnx Its been my experience that Teflon tape no matter how its applied does not work for long exposed to fuel, not to mention its not recommended for use in or around fuel (probably because it dissolves). I guess we are back to the question what does? try this stuff. http://tds.loctite.com/tds5/docs/561-en.pdf Quote Link to comment Share on other sites More sharing options...
sweetleaf Posted August 16, 2007 Share Posted August 16, 2007 Don't use the white Teflon tape, use the yellow thats rated for gas. Are you really asking about PST or do you mean TFE? Either way if it it properly threaded BPT or SPT it shouldn't leak once tight.. I made my own rail with SPT and it sealed perfectly after tightening the fittings. That was for the barbed injector fittings and for the ends I welded on AN fittings. Quote Link to comment Share on other sites More sharing options...
MrFancypants Posted August 16, 2007 Share Posted August 16, 2007 AN (or JIC) fittings are flared and require no sealant. Also take special note not to overtighten the fittings. They take a lot less torque than you might think to seal. You can overtighten and ruin them easily by galling the flared surface of the male side. As for NPT fittings, I use Loctite on the 3-4th threads of the male fitting before assembly. I imagine you could also use suitable RTV. Also take care not to overtighten an NPT fitting. They are flared slightly such that if you overtighten them they can actually split the walls of the female side. - Greg - Quote Link to comment Share on other sites More sharing options...
Scottie-GNZ Posted August 16, 2007 Share Posted August 16, 2007 Try to determine if it is coming from the AN fitting or the NPT fitting. I had a mysterious leak at an AN fitting once and it turned out the flare on the female end was cracked. Quote Link to comment Share on other sites More sharing options...
Tony D Posted August 17, 2007 Share Posted August 17, 2007 Instead of using tape how about PST on the NPT side of the fitting? Seems like it might be less likely to clog something in the fuel system, be it injector or pump or filter... On all our equipment, PST is the ONLY allowable sealant for tapered threads. If I go to a site and see teflon tape on ANY of the joints, I am to note it specifically as to location & condition, inform the customer that he is to remove the affected fittings and redope with PST 597 or equivalent (High Strength PST preferably) and if they refuse, get them to sign a release of liability before proceeding with ANY further work. This has caused much friction in the past. FWIW, I prefer the PST because you don't really need the torque and thread deformation inherent in Teflon/Tapered Thread systems. I find I can make up and remake NPT connections several times without galling, including on stainless steel when using PST as opposed to Tape. The idea of sealing without torquing the hell out of it appeals to me. As always, read the instructions, I find when I clean the fittings and use the primers recomended on some of the fittings...and then give them adequate set time before pressurizing the system it's amazing how little fitting installation torque is required to keep considerable pressures at bay! There are small copper and aluminum washers (Dead soft annealed) from the Cryogenic Industry out there floating around that crush on the face of the A/N 37 Degree Taper that allow for reclamation of a damaged fitting without removing it from the installation, as well as allowing for more thermal expansion without possible leakage---that is the only thing I have ever seen allowed in the 37 Degree Tapered Joint of the A/N Fitting... NAVAIR 1-1A-15, USAF T.O. 1-1A-15.... Oh the hours spent referring to those texts when dealing with just this subject! LOL Quote Link to comment Share on other sites More sharing options...
MONZTER Posted August 17, 2007 Share Posted August 17, 2007 check this link http://aircraftspruce.com/menus/ha/fittings.html aircraft spruce Quote Link to comment Share on other sites More sharing options...
Administrators RTz Posted November 10, 2007 Administrators Share Posted November 10, 2007 On all our equipment, PST is the ONLY allowable sealant for tapered threads. If I go to a site and see teflon tape on ANY of the joints, I am to note it specifically as to location & condition, inform the customer that he is to remove the affected fittings and redope with PST 597 or equivalent (High Strength PST preferably) and if they refuse, get them to sign a release of liability before proceeding with ANY further work. Tony, I did some searching on the PST 597 without much luck. Google, McmasterCarr, etc. The closest thing I could find is a Loctite product 592. http://72.14.253.104/search?q=cache:PhdwvMWOHzIJ:www.barnhillbolt.com/specs/loctite592tds.pdf+%22pst+592%22&hl=en&ct=clnk&cd=1&gl=us&client=safari http://rshughes.com/products/079340_59231.html Is 592 interchangeable for our purposes? Thanks, Quote Link to comment Share on other sites More sharing options...
Tony D Posted November 12, 2007 Share Posted November 12, 2007 Might have been 567...mistype or dyslectic moment... Too dark out now to go look at the tube. Yeah, went and checked your site, and searched on 567: it's 567---400F rating for hot engines and compressors! There also is some 'high strength' stuff out there for permanent installations that will SEAL AND STICK---you will play hell trying to get the fittings out without heating them to relieve the selant's grip! http://rshughes.com/products/079340_56747.html I don't know that I'd use 592, that slow cure stuff takes forever to set up! Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.