# Pipe Dope or Teflan tape?



## RowCropRenegade (Dec 23, 2009)

Which is everyone's favorite sealant for black iron pipe/brass etc connections?

Do some people do both?

Any particular product that you prefer?


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## DAKSY (Dec 23, 2009)

I use the teflon type paste for most BIP connections. 
I used to use the gray pipe dope, till I realized it wasn't approved for LP connections.
Technically, brass-to-brass connections don't require any type of compound, but, WTF,
no sense in coming back for a leaky connection, so I use the teflon paste on them, too.
I just wish it didn't get all over me! *sheesh*


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## jf254 (Dec 24, 2009)

Teflon tape and rectorseal on all boiler connections here... I double them up.. dont want to go out for a water leak early in the morning


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## tom in maine (Dec 24, 2009)

A agree with JF.
Pipe dope on the female ends, teflon tape on the male ends.


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## DenaliChuck (Dec 24, 2009)

My friend who does lots of boiler installs uses a few wraps of teflon tape and then Jomar ("the green stuff") dope over the tape.  Worked well on my system.


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## stee6043 (Dec 24, 2009)

jf254 said:
			
		

> Teflon tape and rectorseal on all boiler connections here... I double them up.. dont want to go out for a water leak early in the morning



+1.  I didn't have a single leak on my system, first time ever working with black pipe.  I put a light coating of rectorseal on, then a few rounds of teflon rope, and then a bit more dope.  Worked like a charm...


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## twitch (Dec 24, 2009)

In my system I did teflon then pipe dope on anything 1 inch or larger.  Less than 1 inch just teflon.  No leaks in more than a year....knock on wood..lol


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## sgschwend (Dec 24, 2009)

I wouldn't mix the two.  Rectorseal and some of the others contain a bonding agent too, I would think the tape would block that bond.

You may find Teflon tape is not applicable for larger diameters, but don't quote me.

I have watched a couple of plumbers use a bar of soap.  

To me the real trick is knowing how many turns to use after engagement.


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## jf254 (Dec 24, 2009)

hvac is my full-time job.. never had problems mixng the two..(for boiler work)


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## sgschwend (Dec 24, 2009)

Jf254, sounds great, success stories are good data points.  I not sure if you are using #5 or not, the Rectorseal that hardens, that would be good to know.

I guess it boils down to personal preference of the compatible material choices that meet the ASTM standards.  We all need to read the sealants directions to see what materials they are compatible with.


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## chuck172 (Dec 24, 2009)

I use wicking and the black permatex. Just watch out for the made in china crap fittings. I've got a few bushings from homedepot with casting sand holes.


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## snowman49820 (Dec 24, 2009)

Be careful the Greenstuff is only good for 120*. I had a small leak this year from it. I now use an industrial paste good for 250*. I've use it for plumbing water cooled production robots.


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## mwk1000 (Dec 24, 2009)

I used the pipe dope thinking it was better, I had to pull the whole thing apart and redo it with tape. No leaks since then.


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## Gary S (Dec 24, 2009)

I've been in the steam and hot water industry since 1980. I always put on a few rounds of tape and cover it with pipe dope, I hate leaks but that's just me.


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## in hot water (Dec 24, 2009)

I like the thick, 3 wrap teflon from Mil-Rose.  Start back a thread or two and add some dope to the first thread.  This blue Leak Lock is great stuff.  Thick teflon tape works great on rough or torn threads seen on many of the import nipples 

On all the straight thread brass we use Loctite, usually the #525.  To dis-assemble you need to heat the connection with a torch, soften the Loctite, then remove as shown.  It sets in about 5 minutes before we air test assemblies.

Hemp is very common in Europe, as all threads are straight, no taper.  Loctite makes a cord, not unlike dental floss to be used on straight threads.

Caleffi actually makes special hemp fittings, as shown.  The sharp mini grooves are to grab the hemp or cord and keep it from spinning off.

hr


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## ISeeDeadBTUs (Dec 24, 2009)

I am about as far from a plumber as . . .

But when I put the piping back together after the nipple weld, I used dope at first, then Teflon Tape. As it happens -not being a pro plumber and all- the very FIRST joint I put together leaked. After the unit cooled down, I disassembled and then reassembled using only the tape. Neater, and it worked.

The pipe dope was NOT the reason for the leak; that was my pizz-poor plumbing skills :blank:


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## jf254 (Dec 24, 2009)

sgschwend said:
			
		

> Jf254, sounds great, success stories are good data points.  I not sure if you are using #5 or not, the Rectorseal that hardens, that would be good to know.
> 
> I guess it boils down to personal preference of the compatible material choices that meet the ASTM standards.  We all need to read the sealants directions to see what materials they are compatible with.



yup using the #5


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## flameretardant (Dec 24, 2009)

Been lurking for years, this post prompted me to register. I've worked oil & gas, pulp mills, concrete plants, water treatment, built my own boiler, etc etc. I see this "more is better" so use dope and tape stuff all the time. Well, just a heads up, it will probably come to a screeching halt. First off, know what you're using - there's "pipe sealant" and then there's "antisieze compound". Antisieze is garbage. Throw that junk in the woods or let the kids fingerpaint with it. It causes more problems than it will ever solve. The paste, teflon-based sealants are good for pipe 1" and over and required by most industrial codes on pipe 3" and larger. Tape is used on smaller pipe.

Now, you need to know (especially people doing this for a living) that there are no tape or liquid sealant manufacturers that endorse or have been certified to use both tape and sealant on the same joint. This opens up a huge liability can of worms. Especially since this issue is not yet incorporated into gas/plumbing codes.There have been a few accidents here involving fittings that have been "double taped and doped", the results of which have been inconclusive as to weather the "doubling up" had anything to do with it but the insurance companies are seizing upon it as a possible contributing factor. Bottom line, using anything that's not officially certified to be used with something else is leaving yourself liable. It is thought that use of 2 substances inhibits the formation of a proper bond since each substance isolates the other from the mating surfaces.  But codes will be updated in time and it will likely prohibit "doubling up", based on conversations with our provincial safety authority. My gas company and most others in the area already have company policies prohibiting doubling up at this time as well. At the very least, it will take time for companies to test and certify the practice of "doubling up" if they can prove it can be done safely. I have used tape and sealant singly for years with no trouble - if you have that many leaks that you need to double up, you're likely doing something wrong.


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## Gooserider (Dec 25, 2009)

For whatever it's worth, probably not a lot...  Our plumber uses Rectorseal #3, followed by a layer of teflon tape, and another layer of Rectorseal - After watching him do it that way, I started doing the same, haven't had any leaks yet, whether on plumbing or hydraulics...

Gooserider


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## jf254 (Dec 25, 2009)

Well you bring up good points. I was taught to double up when I started and have done it since. I haven't had a problem with any of them not bonding. but hey whatever works best for you.


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## rkusek (Dec 25, 2009)

On my "temp" EKO40 install last year we initially just used the Rectorseal and had 2 or 3 that still leaked even after tighening more.  After some advice from the forum, went back cleaned everything, used tape then dope and no problems.  That's the method I'm using now.


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## WES999 (Dec 25, 2009)

When I installed my hot water heater I used used Teflon tape on the 3/4" pipe threads, figured it was not messy like paste, big mistake, I had 2 leaking joints. I took it all apart and redid it with PTFE paste, no leaks. Now I will never use Teflon tape on anything but pneumatic fittings.

BTW Gooserider I would avoid using teflon tape in a hydraulic system, the tape can come loose and foul precision valves.
We had a brand new injection molding machine that malfunctioned due to some Teflon tape lodged in a valve.


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## Gooserider (Dec 25, 2009)

WES999 said:
			
		

> When I installed my hot water heater I used used Teflon tape on the 3/4" pipe threads, figured it was not messy like paste, big mistake, I had 2 leaking joints. I took it all apart and redid it with PTFE paste, no leaks. Now I will never use Teflon tape on anything but pneumatic fittings.
> 
> BTW Gooserider I would avoid using teflon tape in a hydraulic system, the tape can come loose and foul precision valves.
> We had a brand new injection molding machine that malfunctioned due to some Teflon tape lodged in a valve.



I agree that teflon tap can mess up valves, hydraulic or otherwise...  I'm very careful when using it, and only wrap to within 2-3 threads of the end of the fitting. I start the wrap on the wrench end, go to within a thread or two of the end, then come back to the large end again, so that there is no tape actually in the fluid area of the joint, it is all in the threads...  If I have to back up, I take the joint apart, clean both ends, and start over...

Gooserider


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## Hunderliggur (Dec 25, 2009)

I like Gooserider's tape method and will use it in the future.  For my fittings (mostly 1 1/4 but including three 4" future HX holes) I used teflon dope and it worked well.  The Danfoss was a little harder to get a good seal but nothing that two large pipe wrenches couldn't handle.


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## webby3650 (Dec 26, 2009)

Never heard of this "doubling up"stuff. I have never had a leak from failing teflon tape or pipe dope. To me, having to "double up" would indicate another problem. My father in law is a plumber, he has used teflon tape for many many years with no problems or the need to ever double up. Don't make sense to me!


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## RowCropRenegade (Dec 26, 2009)

Merry Christmas and Happy Holidays to the hearth community!

I've never done any hydronic heating piping, until tomorrow.  In all my chemical handling equipment I use teflon.  Mainly because it's clean, easily stored and needs no set up time.  I've had teflon leak, but nothing a re wrapped and cleaned up thread didn't solve.  We are talking lines as big as 3 inch to small as 1/2, mainly plastic stuff.  PSI ranging from 30 to 120.

I won't be dealing with high PSI tomorrow but 200 degree water is the unknown variable.  

Going to pick a can of Rectorseal # 5 so I have a comparison.  IMHO, combining the two sealants sound like a last resort fix.  But what do I know?  The teflan they reccomended me is thicker than the reg white teflan and its blue.  Minimum 3 wraps.

Thanks for the tips!


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## Gooserider (Dec 26, 2009)

Oh, and one other thing that I forgot to mention earlier - per the Rectorseal can instructions, I always try to put 3 turns on the joint past "finger tight"...  In practice, because of needing to line things up, this can actually be something closer to between 2.5 and 3.5 turns, but I always go for at least 2.5 - and if I'm not having to work at getting the last 1/2 to 3/4 of a turn, I go for an extra...

Gooserider


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## DannMarr (Dec 26, 2009)

I agree with fyrewerks and webby, I never mix. Tape or paste work fine as long as you use it properly for the right application.


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