When working with a pipe thread sealant tape (incorrectly referred to as Teflon tape), it is very important to correctly apply it to to prevent a leak.
This is one of those things that require few practice rounds to get comfortable. If you have some time, I highly recommend purchasing practice parts (they are relatively inexpensive) so that you are ready for your next plumbing projects.
REQUIRED PARTS / TOOLS
- Threaded male pipe/connector like this 1/2″ brass pipe fitting
- Threaded female fitting like this 90 degree elbow brass fitting
- PTFE thread sealant tapes – practice with white (LASCO White 1/2-Inch Double Density PTFE Thread Seal Tape) and yellow (Oatey Yellow 1/2-Inch Gas PTFE Thread Seal Tape) tapes to get a different feel;
- To clean pipes and fittings after practice, you can try to use old toothbrushes, or something like mini wire brushes;
ALLTHUMBS DIY STEPS
Over the years, I’ve learned that taking time and paying attention to little details will minimize the risk of leakage (very frustrating to take it all apart to fix a leak!).
In its simplest form, we are trying to apply the sealant tape from the end of the pipe and wrap the sealant tape under tension in the direction of the thread turns.
Each successive layer should overlap the previous layer by approximately 1/2 to 2/3 in width and continue wrapping until the entire threaded portion of the pipe is covered.
In most cases, 2 turns is sufficient (max of 3 turns). If you wrap it the wrong way, discard, and start with a new piece of tape.
- For this exercise, let’s assume that our elbow piece is a RIGHT HANDED thread;
- That means when you are looking directly at it, the threaded piece is designed to be tightened by turning right;
- While looking directly at the elbow as if you are still installing it, visualize a thread sealant tape is wrapped in the OPPOSITE direction;
- For example, a sealant tape is wrapped to the LEFT TURN for a a RIGHT HANDED thread;
- It can get little confusing if you change your viewpoint so make sure that your elbow piece is DIRECTLY IN FRONT of you when visualizing. When installing a tape, this perspective will change because you need both of your hands to correctly install the tape;
- Now take the your TEFLON / sealant tape roll, spool out approximately 3 inches of tape which will be just enough for 2 wrap turns on a 1/2″ thread (you do not want it too thick);
- A circumference on a 1/2″ diameter is roughly 1.6″ (2 turns x 1/6 = ~ 3″). Obviously if your threaded pipe has a larger diameter, you will need a longer tape. If you need help with math, you can always use this calculator from About.com;
- Hold down the beginning of the tape with your left thumb;
- With your right hand, gently tug on the tape until you can see the outlines of threads;
- You can let go of your left thumb once you complete the first turn
- Continue to tug on the TEFLON roll and complete 2 additional turns and cut it off
- Make sure that any part of the TEFLON tape does not go inside the pipe/joint (you don’t want a small piece to rip off later and clog something)
- Carefully apply the threaded piece to the female coupling (if you back out the threaded piece for whatever reason, you need to install a new piece of tape)
DON’T DO THIS!!
If you wrap the thread sealant tape against the turning direction (wrapping it in the same direction), your thread sealant tape will end up bunching up which will prevent the threads from mating properly.
I know it looks very confusing at first but give it a try few times I promise you it will get easier. Just remember to wrap the sealant tape in the OPPOSITE DIRECTION of a thread.
Another option is to use a liquid sealant tape like Permatex Thread Sealant with PTFE which is good for preventing air and liquid leaks. Remember that you want to apply a nice, consistent thin layer, not goop up a whole bunch. It can get messy in a hurry so have a roll of paper towel nearby 🙂
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16 thoughts on “How To Correctly Apply Teflon Tape to a Thread”
Good information Kevin!…You might want to remove one of the instances of the word “paying” in the All thumbs DIY steps (shown below)
ALLTHUMBS DIY STEPS
Over the years, I’ve learned that paying taking the time and paying attention to little details will minimize the risk of leakage (very frustrating to take it all apart to fix a leak!).
Thank you so much! Fixed!
Referring to your initial picture, I find it easier to flip the tape roll over [so tape feeds from bottom] and put my right hand third finger thru the center hole while holding the fitting w/ left hand. That way you can grab the tape roll with your right thumb and forefinger to keep tension on the tape as you wrap the tape onto the fitting.
Try it. Easy to get a good wrap, and then just pull/break the tape when you’re finished. Bruce L
Thanks for your suggestion! It sounds like a good method to try.
Well explained and illustrated teaching tool. Thank you.
Is it necessary to screw the thread all the way in?
For example I have a compression elbow that I need to face a certain way but the thread still has more turns in it but if I turn anymore then it faces the wron way?thanks
are we talking gas or water?
very helpful as I venture to find a leak somewhere on the suction side of my pool. I went back to redo the drip values correctly (thanks to you) and now problem fixed. thanks again.
awesome. thanks for letting us know!
Bruce L’s comment about flipping the roll over is an absolute must. (The outside of the tape, as it’s on the roll, will be what contacts the pipe.) This method helps keep tension on the roll and makes it easy to stretch the tape as it’s applied to the threads. and keeps tension on what’s left on the roll.. Also makes it easier to stretch/break the tape at the completion of the wrap job. The thinner the tape, the more this method helps.
You didn’t mention the importance of not allowing the tape to extend over the end of the threads. On any application where even a small piece of stray tape could interfere with valve seats or small orifices down the line, this is critical. I recommend leaving 1 – 2 end threads tape-free. The lead threads have minimal contact, hence minimal sealing power, with the connected female threaded fitting. The larger the pipe size the more this holds true.
Thank you for your thoughtful comment!
Very helpful, some details I did not know.
Right handed thread. Just hold the pipe (or screw for that matter) up and you can see that the crests of the threads all go up and to the right. This means that you twist it clockwise to screw it into the female fitting. Left handed threads will go up and to the left. There are very few of them in everyday life but that’s how you tell if you’ve got a right handed or a left handed thread.
Richard comments that he is using tape on a compression fitting. Also, a picture of a compression fitting is shown in the article. Tape makes for a good seal on tapered pipe threads which sometimes are on one end of a compression fitting but do not use tape on the fine threads of these fittings. The brass “wedding band” is the seal. This thread is not intended to seal water and will leak if you do not have a good seal at the compression band.
Yes, I agree that these tapes are for threaded applications. Thanks for clarifying it for the readers!