Pipe dope for brass gas line connections?

Greenfrog

Member
What kind of thread sealer do I use for brass threads where it is exposed to gasoline?? For example, where sediment bulb /shut off connects below tank and on the brass barbs on an in-line shut-off. Teflon? Probably not for gasoline. Or maybe use none.....
Advise please. Thx in advance.
 
Teflon tape will work, but you have to be very careful not to get any beyond the end of the fitting as it can clog fuel system components.

I like "Permatex Form a Gasket #3". It is gas resistant, and not supposed to clog if it gets in the line, but still, be stingy with it.
 
I also use the Permatex Foam a Gasket that's good for gasoline and doesn't set real hard. If the threads are good on fitting I some times use nothing.
 
(quoted from post at 23:17:41 12/20/17) Teflon tape should not be used in any pipe installation.

[u:819987ed8d]Please [/u:819987ed8d]give us more details as to why Teflon tape should not be used in any pipe installation. I am sure the millions of other users of Teflon tape would like to know more.
 
Teflon tape melts in gas so then it can get into the carb and clog things up big time and can then go back to a solid which can make cleaning it out almost impossible
 
NOTHING. Many things if you try to use them gas sort of eats or melts and then it can end up in the carb and cause major head aches and even cause a carb to need to be replaced
 
Yes, just learned that at local ACE hardware store. However we concluded that that kind was for natural gas or LP and not for gasoline and decided not to use it. I think I will use nothing, brass fits good together.
However, all of you who replied here brings up something, in fact might have solved a mystery: last summer I had the 1942 CASE SC into a local implement dealer shop to get carb cleaned and rebuilt. After that, It actually began to run badly and became harder to start. I seeked a second evaluation from another mechanic. he took carb apart and found a gob of something in the intake jet. Wonder if this was Teflon tape?....as they put an inline filter and a brass shut-off inline in the gas line and used Teflon tape. .????🤔🤔🤔
 
(quoted from post at 20:17:41 12/20/17) Teflon tape should not be used in any pipe installation.

Wow! it looks like WGM is recommending that all teflon tape be dumped and the manufactures close their doors.
 
I needed some sealer for an LP line and got Blue Monster from a plumbing supply. Good for just about anything but Oxygen. Even sealed a bead on a small snow blower tire.
 
I use Blue Monster for fuel and water lines. I just keep the stuff from near the end of the male part so it does not get into the line.
Richard in NW SC
 
Have to agree with 504 on GASOIL thread sealant,it is gas resistant,have used it on Super-C where shut off valve and bowl screw into bottom of tank,never has leaked a drop!Even use it on compression fitting nuts as a backup just in case!
 
Generally speaking, the condition of the thread or the mating surfaces is most important... If it's a flanged connection, using some PTFE dope on the threads, only provides some lubrication, so that the connection can be properly torqued. If it's a pipe thread connection, the threads are the mating surfaces, and their good condition, and cleanliness is essential... A good PTFE, like Gasoila, will do the job well... Again, it's primary purpose is lubrication, allowing for a proper torque to be applied to seal the threads.
 
(quoted from post at 09:40:41 12/24/17) Generally speaking, the condition of the thread or the mating surfaces is most important... If it's a flanged connection, using some PTFE dope on the threads, only provides some lubrication, so that the connection can be properly torqued. If it's a pipe thread connection, the threads are the mating surfaces, and their good condition, and cleanliness is essential... A good PTFE, like Gasoila, will do the job well... Again, it's primary purpose is lubrication, allowing for a proper torque to be applied to seal the threads.

Do plumbers or pipe fitters really use torque wrenches? I googled teflon tape uses and found two mentions of lubricating and ten of sealing, Two said that the tape haps in getting the fittings tight, while all of them said it seals. Two mentioned filling tiny voids and imperfections in the threads.
 
I'll add to my own question and to the discussion here....
An old time plumber always told me that pipe dope was used to no only seal, but to allow it to come loose more easily in the event that one should have to take it apart...especially in galvanized pipe.
I also have read that some plumbers use both--tape and dope.
Anyway, good discussion here....good common interest....thx for all the input
 
He sure is. Tape is nothing but crap made for use by pretend plumbers/fitters. There has been plenty of good products mentioned here by others. Use one of them. Tape is not one of them.
 

Your question must be rhetorical... The answer is... No, plumbers don't use torque wrenches, their work is done mostly by feel, though, there is a rule of thumb, hand tighten plus two full turns.

There are a couple of types of fittings that we could be dealing with; Flared fittings, used in both hydraulic fittings and fuel systems. And, tapered NPT fittings...

I think for the most part, we'd see flared fittings in the fuel systems. In either case, using tape is discouraged, because there is a chance for pieces of tape to to migrate into systems and cause problems. But, in a flared connection, the condition of the flared mated surfaces is most important. Having a lubricant on the threads will ensure that it can be tightened properly. Torque, is an acceptable term to use... As it's a rotation force.

Tapered NPT fittings are a interference fit, where if they are machined perfectly, and lubricated, and tightened, it is theoretically possible for them them to form a hydraulic seal. But, since manufacturing techniques are knocking out thousands of parts in a run, tolerances can't be kept close enough to achieve that kind of result.

I personally like a paste, because it has the ability flow better, and seal imperfections in materials. But, again make sure everything is very clean.
 
(quoted from post at 15:45:35 12/25/17)
Your question must be rhetorical... The answer is... No, plumbers don't use torque wrenches, their work is done mostly by feel, though, there is a rule of thumb, hand tighten plus two full turns.

There are a couple of types of fittings that we could be dealing with; Flared fittings, used in both hydraulic fittings and fuel systems. And, tapered NPT fittings...

I think for the most part, we'd see flared fittings in the fuel systems. In either case, using tape is discouraged, because there is a chance for pieces of tape to to migrate into systems and cause problems. But, in a flared connection, the condition of the flared mated surfaces is most important. Having a lubricant on the threads will ensure that it can be tightened properly. Torque, is an acceptable term to use... As it's a rotation force.

Tapered NPT fittings are a interference fit, where if they are machined perfectly, and lubricated, and tightened, it is theoretically possible for them them to form a hydraulic seal. But, since manufacturing techniques are knocking out thousands of parts in a run, tolerances can't be kept close enough to achieve that kind of result.

I personally like a paste, because it has the ability flow better, and seal imperfections in materials. But, again make sure everything is very clean.

Eric, I think that you mean metal-to-metal thread wedging as the mechanical means by which tapered threads seal. An interference fit is one with no threads involved, as it is just the friction between two parts that are pressed together, rather than by any other means of fastening. I have numerous times applied a little lubricant to not only the threads, but also the mating surfaces of old flare fittings that didn't want to seal. A trick I learned from an old plumber many years ago.
 

I'll agree to your point, on the interference fit... I'm certain that I misapplied the term.

I agree, too, on the point of lubricating the flared fittings.

So, overall, I think we're in agreement.
 
If you use Teflon tape on gas or oil, make sure it is yellow, that said I personally don't use Teflon tape. I have problems with it leaking 2 or 3 years down the road. I use rector seal on everything that needs sealer which is tapered pipe treads only.
 
I read somewhere long ago that Teflon Tape is not a sealant but adds lubrication to threads so they can be tightened. I only use a liquid sealant on threads. Been using Blue Monster from Lowes. Works well.
 
(quoted from post at 19:09:04 12/29/17) I read somewhere long ago that Teflon Tape is not a sealant but adds lubrication to threads so they can be tightened. I only use a liquid sealant on threads. Been using Blue Monster from Lowes. Works well.

Or you may have read it today on this thread,
 

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