Need a pro's help with threaded fittings

ChrisJ

So far I've had very bad luck putting together NPT fittings in plumbing.  Some how my sweat joints are very good but most of the threaded connections I make for domestic water leak.  I have to assume I'm doing something wrong.

I use the typical thin white teflon tape and do 3-5 wraps and tigthen the fitting fairly tight.  Half of the time I end up with a connection that slowly wheeps.

These connections are all 3/4" if it matters.

Paul Fredricks_3

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Everyone has a different way of doing fitting.



My way is a thin coat of Rectorseal #5, then 2 wraps of teflon over that. And you have to solder the pipes to the the fitting before threading it in. If you thread in first, then heat it to solder, the joint will fail.



This is the way I do it and it has served me very well for nearly 30 years.

JohnNY

Our way...

We still use quick wick and pipe dope. My brother throws a minor tantrum when he sees our guys using teflon tape: This aint a hobby! Let,s use PROFESSIONAL tools!



Fun stuff like that.

MikeyB

Wick & Dope

I agree w/ john, I was taught by my old Bosses to use Spool Wick/Lamp Wick along w/Pro Dope or Real Tuff, especially when installing new nipples into old fittings, since the old fittings were stretched out, a Fitter had told me a long time ago that the reason the Wick is the best is because it swells when it gets wet, and alot of times when using Teflon it acts as a lubricant more than a sealant

Robert_25

You need pipe dope, and make sure the fittings are tight

Three wraps of Teflon tape and Pro-Dope or GRRIP over the tape works great for me.

meplumber

Paul makes a great point.

If you solder copper to the male adapter after you make up the threaded connection, it will leak. Make the solder connection first, then make up the threads. I try not to solder with 6" of a male or female adapter.



If I absolutely have to, I keep the heat really low and cross my fingers.

Ron Jr._3

We tried a few combos

over the years . Used Teflon tape and Rectorseal a long , long time . Just 2 wraps ( the same way the ppe threads in the fitting ) and paint over the Teflon with the sealant . For anything over 1 inch we put thread sealant on the inner threads of the fitting as well . Any domestic fittings any size get tape and sealant on all threads too . Rectorseal is great stuff . Easy to coat fittings , works well in the cold weather . You can pull a 20 year old fitting apart with ease . That can be a blessing and a curse though . And the other pros are right about soldering the adapter first , then tightening . If you solder after , the fitting will be hand tight if you used Rectorseal . They won't always leak , but one in 20 might ......    



We use Teflon tape and Pro Dope now cause that's what the store stocks . It's a harder setting sealant . No problems soldering a fitting after it's tight . MUCH harder to take fitting apart with Pro Dope . But I do like the stuff . And it won't run out of the can if it tips over , like Rectorseal

Paul Fredricks_3

true

more than once I've found the can of Rectorseal on it's side, sometimes coating my tools. What a mess. But I do like how easily it can be applied. Used to use Pro Dope, but now prefer Rectorseal #5. A lot of our guys are using Gasoila.



And I hate GRIPP, at least I hate trying to take a fitting apart that has it on there. Might as well weld the pipe together.

ChrisJ

Megaloc

I have a large can of Megaloc and tons of Blue Monster tape which I bought on Gerry Gill's recommendation for steam pipes.  Will these work good for domestic water also?  My immediate assumption is the tape might be too thick for small fittings.

Charlie from wmass

I think ME plumber found the problem

are you soldering after installing the fittings? If you have been do as Me Plumber suggested. I use Pro dope and teflon for copper or brass to iron connections. I also will put a damp rap on the threaded joint if I need to solder close to it.

ChrisJ

Solder before connecting

Sorry guys I forgot to answer that.  I have been threading the adapters on, marking to ensure I solder it in the correct position to the pipe and or fitting, removing, soldering and then reinstalling them.



The idea of the damp cloth is a good one.  I didn't think of that.  I have a connection I need to repair and its in a terrible spot where I may have to sweat the fitting off in place and then resolder it in place.

Robert_25

Quick wick?

I would like to hear a little more in the use of wick in threaded fittings. I recently found an old can of plumbers wick, but I have never seen it used. How many wraps are you supposed to use? Do you go across the threads or try to seat the wick in the thread valleys?

Paul Fredricks_3

AS I recall

It's just thin thread. You wrap it in the valleys. hold the free end against the pipe and run it forward to the end thread, then wrap in the valleys working your way back. Used to use it for old fittings and when I cut with the sawzall a little to deep and nailed the threads. Used to use wicking, with teflon on that, with prodope on that. never a leak.

MNSteve

re: teflon tape

I work at a high pressure compressor company where almost all of our plumbing is pipe threaded connections. We typically just use teflon tape for these, and they usually stay air tight in excess of 6000psi. However, I have noticed the same problem when I try to use teflon tape in plumbing fittings. I almost always get a small leak. So I have learned my lesson and use teflon pipe dope on my plumbing connections.



I think the reason the tape works with the high pressure fittings, but not the plumbing fittings is a difference in the thread standard that they are made to. The high pressure fittings that we use are threaded with an NPTF standard (also known as NPT Fuel or NPT Dry seal). The threads are specifically formed to avoid spiral leaks. On the other hand, I believe most plumbing fitting are standard NPT which has a slightly different thread profile and requires a sealant to stop the spiral leak. As others have said the tape acts as more of a lubricant than a sealer.

ChrisJ

NPTF

Steve,



I was under the impression NPTF fittings did not any thread sealant as they were designed to be air tight on their own?





And..... I just noticed you basically said that.

ChrisJ

finally got it!

I sweated the pipe apart with a wet rag on the fitting, put it back together with megaloc only and it leaked again. Pulled it all apart and looked closely at the fitting and found cutting marks in the threads. Best guess is they are from the machining of the fitting it definitely doesn't look cracked.



This time I used 3 wraps of the blue monster PTFE tape and applied megaloc to the female threads of the copper fitting, threaded it together and its not leaking. I guess I should have listened to everyone the second time .



I was almost ready to just leave it leaking as its only a temporary installation for a month or two, but I felt it was a learning experience so kept at it.

MikeyB

Lampwick

Rob, the way I was taught was to start the wick in the middle of the nipple/pipe thread, then work your way down toward the beginning of the thread, then bring it back up toward the top.This way the middle of the thread has the majority of the wick, so the fitting will rest on the middle of the thread. And before installing the fitting paint on some dope