Pipe Thread Sealant

[Matt Bachand]

I have been looking at some parts I've been getting, and I am noticed Red pipe thread paste on the threads.

Now this is dried up before shipping and ready to assemble.

I have some pipe thread compound that is yellow. I have been having leaks.

I have NOT been allowing the compound to dry before install.

Do I have an incompatible thread sealer or am I using it wrong?

 

[jrsavoie]

Don't know your product. I always use teflon tape and any good quality pipe dope. No leaks

 

[schiker]

Maybe just air pockets due to dried stuff underneath the new stuff. It might be rolling up or making "pills" etc. Might be worse with different formulations. Stuff that dries harder would be worse mixed with softer stuff????

I think you are suppose to start most products on clean dry threads. If I ever take a fitting out with dried goop on I try to wire wheel or brush the crud out of the root of the threads. Yeah, I have had leaks too occasionally sometimes the threads are just bad fits and it takes extra care in prep and tighten NPT up pretty good. If its a cheap fitting sometimes they just leak or will plastically deform and loosen with time. Had a gas (air gas not liquid gas) pipe tech tell me to only use forged fittings on gas as the cheap ones give lots of problems for gas lines as they are prone to leaks after time from the plastic deformation and deterioation of sealant.

I have read many argue for or against tape or dope. To me its all in the prep and cleanliness of application. Stay off the first thread or 2 and apply the stuff uniformly and get it down to the root of the threads evenly around wiping off excess. Then most any decent stuff should work.

Also, dope can seperate so stir or knead the tube throw the really old out. Tape tends to store longer for inactive use.

 

[Matt Bachand]

So you can apply it wet and install immediately or is it a must to let it dry first?

I always used teflon tape, but all the fuel pump directions and Racor directions all say use the paste incase a piece comes free it doesn't not clog upstream.

I really liked the paste, until my U that I made out of a few different fittings leaked.

However, like all NPT you are limited to a certain position if you can't make it another 360.

I noticed my Walbro Fittings had red dried on it.

I also noticed My new OPS has red dried on it.

Both came from PMDCABLE.com, so maybe he does this as prep to prevent leaky callbacks?

Looks too factory applied though.

 

[540s10]

pipe thread seals on its own, teflon tape and paste are only 'supposed' to be lubricants, the threads do the actual sealing.

 

[ak diesel driver]

that's the theory anyway

 

[jrsavoie]

I ain't buying it. The threads aren't machined enough to hold pressure. About 35 years ago a wise old man told me to use tape and dope both. One is to seal and the other is so you can take it apart later. I followed his advice ever since and I've never had leaks - except on stainless fittings. I even converted a plumber/fitter. I don't know why but we always had a few problems sealing stainless. Usually a leak on every job.

 

[ak diesel driver]

that was intended as sarcasm. Even tho the threads are supposed to be self sealing there are to many imperfections, cheap pipes, cheap or dull tooling, etc

 

[schiker]

So you can apply it wet and install immediately or is it a must to let it dry first?

"Pipe dope" (the teflon pastes) I have always applied and install still wet. And its ready once tightened. Different formulations and products will set up hard some semi-soft.

Thats why I say its in the prep and cleanliness of applying sealant. The first thread is not full and not going to seal. Anything on the end of the fitting might shear off and get into the system. Dope theoretically should be soft or semi fluid and disperse in the system fluid.

 

[Burning oil]

One trick to using tape, apply it so the first thread or two are raw/exposed that way it cannot get into the system. If you are sloppy with it and its hanging over the edge then yes it can cause a problem.
Same will soft sealants just leave the first 1-2 threads exposed.

 

[jrsavoie]

On the stainless steel subject. Does anybody know of a particular product good at sealing stainless?
I have 2 theories on the problems we had. One that stuff doesn't adhere to stainless as well.
And that the cutting oils used on stainless should be cleaned off with a cleaner as apposed to just being wiped down with a rag like we did most of the time.
Or both.

 

[Ratman]

On the stainless steel subject. Does anybody know of a particular product good at sealing stainless?
I have to theories on the problems we had. One that stuff doesn't adhere to stainless as well.
And that the cutting oils used on stainless should be cleaned off with a cleaner as apposed to just being wiped down with a rag like we did most of the time.
Or both.

A product we use here at work on all our NPT swagelok fittings is a product called True Blue. It is made by Rectorseal and has teflon in it for thread lubrication, and it has excellent anti-seize characteristics on stainless. It dries semi-hard, and actually performs very well as a thread locker once it cures.

Of course, cleaning cutting oil residue off with acetone or MEK is always a good idea as it goes a long way to promoting adhesion of the product you are using.

I used to work with two NAVY guys here at work that were boiler tech's, -and they argued with me over the whole "pipe dope and teflon tape are strictly for thread lubrication" debate.

I told both of those guys, -as it pertains to NPT threads, -if what they were telling me was 100% true, I would challenge them to a little experiment. I told them that anti-seize was some of the best thread lube out there, -and that I would challenge them to a gas leakdown test with them using nothing but anti-seize for thread lube, -and I would use teflon tape. ):h

There was definitely some serious :thinking: going on, -and they both declined and admitted that they got my point. :thumbsup:

To be real honest, I think tapered pipe threads suck. Some of my favorite threaded couplers are the o-ringed hydraulic-style, and the JIC.

Rectorseal True Blue is definitely some of the best stuff I have used, -but sometimes you need something that is more impervious to chemical, -and that's where the other Rectorseal and Loctite products come into play. I built a pump that pumped some proprietary "ketone", and I had to use Rectorseal #7 on the mechanical seal quench fittings, -it worked exactly as advertised, -as the unit had to pass a strict "emissions test" prior to being commissioned.

 

[NVW]

I have way better luck with Teflon tape than I do with Teflon paste on npt pipe fittings for 2000+ psi hyd. fittings.

 

[Ratman]

I have way better luck with Teflon tape than I do with Teflon paste on npt pipe fittings for 2000+ psi hyd. fittings.

Me too, in fact the stuff that is my favorite on NPT is the gas-rated yellow tape, I use that on practically everything (unless something else is spec'd).

This is a bit embarrassing to admit, but one time I used a combination of teflon tape and red loctite to arrive at a particular flange to flange dimension (some salesguy or engineer blew it on my drawing). I was left with no other choice due to a hardcore delivery date.

The good news is that it worked, -and has never leaked, -and it has been in service for over 15 years, -at 4800 psi to boot! I routinely speak with that customer, and all is well.

 

[NVW]

Me too, in fact the stuff that is my favorite on NPT is the gas-rated yellow tape, I use that on practically everything (unless something else is spec'd).

This is a bit embarrassing to admit, but one time I used a combination of teflon tape and red loctite to arrive at a particular flange to flange dimension (some salesguy or engineer blew it on my drawing). I was left with no other choice due to a hardcore delivery date.

The good news is that it worked, -and has never leaked, -and it has been in service for over 15 years, -at 4800 psi to boot! I routinely speak with that customer, and all is well.

I like that too, or a good industrial Teflon tape. I've built hyd. components with the paste to just tear it apart and use tape.

Engineers or draftsmen often blow it. I used to proof read every thing then go ask if they wanted item A or item B in a given spot):h They couldn't have both.

Disclaimer: Not knocking any Engineers or Draftsmen on this Forum. Unless you were employed at any of my places of employment

 

[83GMCK2500]

I have way better luck with Teflon tape than I do with Teflon paste on npt pipe fittings for 2000+ psi hyd. fittings.

I was also told to use teflon tape very carefully on hydraulic fittings. The reason I was given was that the tape will fragment/flake apart and those bits can tear up hydraulic pumps.

 

[Ratman]

Disclaimer: Not knocking any Engineers or Draftsmen on this Forum. Unless you were employed at any of my places of employment

-Or MINE ):h

 

[Ratman]

I was also told to use teflon tape very carefully on hydraulic fittings. The reason I was given was that the tape will fragment/flake apart and those bits can tear up hydraulic pumps.

True, -having little pieces of teflon in a hydraulic system surely isn't great, -but a little common sense applies (as one of the others pointed out holding the stuff short on the last several threads).

And, while it is true that little threads of t-tape floating around in a hydraulic system ain't great in terms of spool/shuttle valves, accumulators, or unloaders, the 5 micron filters on the low-side do a great job of filtering that stuff out, -even though it isn't the greatest scenario.

I apologize if I have hijacked this thread and turned it into the "hydraulic" thread, -but the same theories directly apply....

 

[83GMCK2500]

Rich, thank you for your contribution to the topic of hydraulics. I have been advised, in the past, that if I do use teflon tape on hyd fittings to leave it back a few threads to reduce the possibility of it entering the system.

Much of my experience comes from growing up on a farm. With the hydraulic system of JD tractors being shared with the transmission it was that much more critical to reduce the amount of contaminents. Most, if not all, of our tractors had dual filters, but I doubt they were 5 micron rated, whatever standard JD cartridge hydraulic oil filters are.

Yup, we've hijacked.

 

[davo727]

For pipe threads in automotive use on the engine block, oil system, coolant system I use Versachem #2 or permatex #2 , i think they are identical. Stuff does not leak. Also great for head bolts. Dont get it on your skin cause its not coming off.