Simple plumbing question re: teflon tape

JDeereman · Aug 9, 2008

Simple, stupid question regarding the use of regular white teflon tape - do the number of turns you are supposed to use vary with pipe size, thread type and pipe material? seems that the standard rules don't apply with very small or very large pipe sizes. also seems to work different for me with brass vs steel or iron fittings and fine vs coarse thread. what is your experience and recommendation? and please no advice about using teflon joint compound instead. i know it is better but today i need to know about using teflon tape. thanks.

Theo

CCWKen · Aug 9, 2008

I think a lot of folks get into trouble by using too much tape. NPT is supposed to be self sealing threads. Using too much won't allow the joint to go far enough up the taper to seal. I use no more than two wraps. It seems to fill enough of the "cracks" to make a good seal and allows easy disassembly later. If you do use it on hydraulic lines, make sure none of it comes within about 1/8" of the end of the fitting.

I'm not a plumber so take this as a suggestion only but I've run a lot of water, oil and air lines and never had a problem.

Sherweld · Aug 9, 2008

What he said.

Plumbing Repair Guide: How To Use Teflon Tape - ACME HOW TO.com

ray66v · Aug 9, 2008

3 turns of teflon is the rule I was taught by a master plumber. 1/2" wide tape covers up to 1 1/4" pipe use 3/4" wide tape on larger sizes.

Using a thin coat of dope with the tape is preferred by many plumbers. This helps to reduce the friction, and helps keep the teflon in tact.

Bentwrench · Aug 9, 2008

Above answers are correct. On brass & copper the threads are usually smoother so less friction two wraps is usually good. With brass, copper, and malable iron too much tape can lead to over tightning causeing the fittings to stretch resulting in leaks. Plastic and tape is a "no". Cast iron will not stretch but to much tape and really over tightning can crack them.

ampsucker · Aug 9, 2008

anybody else prefer pipe dope over the tape?

i bought a decent size bottle of the white pipe dope/putty and have never looked back. on the can it says it is good for water, air, natural gas, propane, hot/cold, just about anything except strong oxidizers.

whenever i've watched a plumber, they almost always seem to use the dope and not too many choose the tape option.

just curious if this is the norm or if there is some good reason to go with one over the other.

amp

Inspector507 · Aug 9, 2008

Around these parts, tape is used for water, dope is used for gas.

EddieWalker · Aug 9, 2008

I put some new water valves under a kitchen sink on a remodel that I did that leaked with teflon dope. I took them off and used tape without any leaks. For the life of me, I can't figure out what I did wrong, but now I only use tape on water lines.

I use two wraps as I'm worried about too much.

Eddie

JDeereman · Aug 9, 2008

Thanks to all who replied. from your collective suggestions, i think i see where i may have been going wrong and not getting really great results. i'll go back and try again armed with this info. thanks!

Theo