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Old 07-26-2016, 02:32 PM   #1
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Sealant For Fuel line fittings

Is there a Sealant recommended for diesel fuel line fitting and connections ??
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Old 07-26-2016, 04:21 PM   #2
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Lots of different fittings are used on marine fuel lines: copper compression, single and double copper flares, Parker and similar tapered cone fittings and finally hose barbs with clamps.


With the exception of the last one, all of these are designed to seal with no sealant. If you can't get one of these fittings to seal without a sealant or maybe a squirt of WD40 for lubrication while tightening, replace the fitting.


David
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Old 07-26-2016, 05:09 PM   #3
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Rector seal. That's what Tony Athens on boat diesel recommends Available at Home Depot
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Old 07-26-2016, 06:12 PM   #4
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Originally Posted by jleonard View Post
Rector seal. That's what Tony Athens on boat diesel recommends Available at Home Depot
Yes, I've had the best luck with Rector Seal #5, but as djmarchand points out, many types of joints are meant to be dry. Rector Seal or other sealant is for tapered pipe threads.
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Old 07-26-2016, 06:21 PM   #5
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Very good comments above. I've had excellent experience with Permatex product as used by two mechanics I respect.

https://www.permatex.com/products/ga...lange-sealant/
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Old 07-26-2016, 07:06 PM   #6
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djmarchand: Perhaps I misunderstood your statement. Hose barbs and clamps need a sealant ?
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Old 07-26-2016, 10:27 PM   #7
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djmarchand: Perhaps I misunderstood your statement. Hose barbs and clamps need a sealant ?
No, but that is the only type of fitting that might benefit from a sealant.

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Old 07-26-2016, 10:30 PM   #8
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Ditto on Rectorseal #5. I've used it on all sorts of fittings to include metal and plastic--it works quite well.
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Old 07-27-2016, 12:20 AM   #9
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NAPA used to sell a product called WOGS for water, oil, gas, sealer. They still sell it but just under their own name now, not WOGS anymore. Probably something to do with political correctness? Anyway its a brown gooey stuff that does semi harden overnight and it works very well, even with gas. I had to just the other day take apart a leaky stand pipe fitting on top of my fuel tank and doped the threads with it. Stuff works. That of course was when the galley table came down on my nose!
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Old 07-27-2016, 05:14 AM   #10
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Rectorseal good.
OR, Seal All sold at Home Depot is good. Seal ALL will seal up gasoline fittings. Is a clear liquid dries to a hard rubber plastic. And it does work on gasoline, I tried it out.

Seal-All

There are very few sealers that will works with gasoline since it now has 10% alcohol.
I have even coated metal parts with Seal All for immersion in gasoline. Like as in filter housings to prevent rusting.
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Old 07-27-2016, 09:29 AM   #11
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The important thing about sealant is to not get any on the end of the thread where it can get into the fuel. I use both Rectorseal and Teflon tape but insure neither is applied so any sealant gets on the end of the male threads.

David,
Do you have no sealant on the many pipe thread joints on your boats fuel system? Never heard of that and do'nt see how it could be but many (as in many many) use sealants on gasketed mating parts (especially on engines) whereas the gaskets seal the joint. And using sealants where none is required or intended could lead to leaks probably dependant on the sealer used.

Plumbers universally use Rectoseal (or equivalant) on pipe threaded joints in the industry so why do they do it?
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Old 07-27-2016, 10:17 AM   #12
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It's Leak Lock for me. Never failed me yet.

Highside Chemicals Inc. manufacturers Leak Lock and Leak Lock Gold.
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Old 07-27-2016, 11:15 AM   #13
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There are different types of "threaded joints". Those with tapered threads should be "sealed" those without should not. A flare and/or compression fitting that has a "sealant" may diminish the mechanical nature of the fitting. If the liquid gets to the sealant then it means the mechanical fitting is not working. A thread compound might be used to allow for easier dismantling but need not have sealant properties.
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Old 07-27-2016, 11:18 AM   #14
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Quote:
Originally Posted by Nomad Willy View Post

Plumbers universally use Rectoseal (or equivalant) on pipe threaded joints in the industry so why do they do it?
Tapered NPT threads (common in standard plumbing fittings) actually require sealants to work correctly. Some good info on sealing fuel fittings here:

How to Properly seal Fuel Fittings and Fuel Lines
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Old 07-27-2016, 11:30 AM   #15
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Quote:
Originally Posted by Heron View Post
Tapered NPT threads (common in standard plumbing fittings) actually require sealants to work correctly. Some good info on sealing fuel fittings here:

How to Properly seal Fuel Fittings and Fuel Lines
I have had worn stretched brass NPT fittings that I soldered together for fuel systems.
Once soldered with a torch and acid flux, that is very solidly sealed.

Torch also will take them apart, and can also put them back together. I repaired my 45 year old fuel manifold doing that. All the valves were disassembled, I was soldering only the threads. I had some that were just too loose for any sealant to hold.
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Old 07-27-2016, 11:47 AM   #16
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Heron,
That's what I thought. Good link.

717,
60/40 lead/tin I assume. That's really interesting. Don't think I'd be inclined to heat ball valves though. Can one insure solder won't get into fuel lines during assembly? Think I'll stick to tape and Rectum seal.
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Old 07-27-2016, 11:50 AM   #17
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On threaded fittings I used Permatex #1. Available everywhere and works great.
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Old 07-27-2016, 02:16 PM   #18
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Tapered pipe threads, NPT and others, were designed to seal without sealers. The catch is that works ONCE, for the initial tightening but not for subsequent uses, and requires accurate, good quality machining.

In most cases that is not the case. Even if a new fitting is used the threads it screws into may have been altered by the removal of the first fitting so that seal cannot happen.

Sealers are used to fill the tiny gaps between threads that almost always occur. Many fluids may not leak as they are too viscous but many will, including gasses.

Plumbers and anyone working with fittings,, pneumatics, hydraulics, gas fitters, use sealers routinely because the consequences of a leak from one lousy fitting can be major rework and very expensive. Not just the cost of the part but the rework time , the mess, the lost production and all the associated costs.

There are places that sealant should not be needed such as JIC, compression, flares unless they have been damaged in which case they actually should be replaced but where those fittings are adapting to a NPT a sealer is almost always used. In the case of the flares, JIC, compression, sometimes the damage is minor enough and pressure low enough that a sealer will work. I have used some Loctites in those cases, small quantity just to fill the gap, not gobs. However unless darn positive of no leaks after, it was replacement time.

I should mention that many fittings use either an O ring for the seal or a crush washer that should be replaced each time that fitting is disturbed. The actual threads are straight, not tapered. Many, many of those types of fittings are used industrially.
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Old 07-27-2016, 02:31 PM   #19
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Quote:
Originally Posted by Nomad Willy View Post
Heron,
That's what I thought. Good link.

717,
60/40 lead/tin I assume. That's really interesting. Don't think I'd be inclined to heat ball valves though. Can one insure solder won't get into fuel lines during assembly? Think I'll stick to tape and Rectum seal.
The valves on mine are cone valves, so they come apart easily. They are just like this.

http://www.walmart.com/ip/Moeller-02...&wl13=&veh=sem

Likely you could solder a ball valve, simply keep the ball-handle part of the valve submerged in water.

Sure, no solder gets in there, you can look inside. The threads are getting soldered only. You put flux on the threads, and tighten up the threads, then run some solder on them. Just tighten by hand is all it needs.
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Old 07-27-2016, 08:20 PM   #20
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NPT threads are designed to use sealant.
NPTF threads are dry sealing.
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