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by Taryn Hardes on Wed, Oct 30, 2013 @ 13:10 PM
It's a simple procedure, but it must be done correctly to prevent leaks
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PTFE Tape is thread sealant used on male tapered pipe threads to aid in sealing. This 3-minute clip shows how to apply the tape. 
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Tapered pipe threads are one of the most common end connections found in industry. They are relatively simple to make up, however they always need a sealant since there are designed-in gaps between the male and female threads.
Filling gaps between roots and crests
There are many different sealants available. One of the most popular is PTFE tape. The letters stand for polytetrafluoroethylene. It's a thin film that fills in the gaps between the roots and crests of tapered pipe threads. PTFE tape lubricates the threads, which allows them to be more easily screwed together, to the point of deformation, which is what creates the seal.
Swagelok PTFE tape provides reliable sealing on metal pipe threads in applications up to 450 degrees Fahrenheit, or 230 degrees Celsius. It conforms to Commercial Item Description A-A-58092.
Assembling tools
To properly apply PTFE tape, you'll need a couple of tools in addition to the roll of tape:
- An open-end wrench
- A dry, soft-bristled brush
- A vise or back-up wrench for the female pipe fitting
Make sure that PTFE is right for the job. It should be used only on male tapered pipe threads. Do not use it on straight threads such as those used on flared, coned or tube fitting ends.
1. First, use the soft-bristled brush to thoroughly clean the male and female threads to remove all previously applied anti-seize compound or tape. Use 1/4 inch wide tape on 1/8 inch, 1/4 inch, and 3/8 inch male tapered pipe threads. Use 1/2 inch wide tape on 1/2 inch and larger male tapered pipe threads.
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2. Wrap the tape in the direction of the thread spiral of the male pipe thread beginning with the first thread. Tape should never extend beyond or overhang the first thread. If it overhangs, the tape could shred and get into the fluid system.
3. While keeping the edge of the tape parallel to the face of the fitting, wrap two to three revolutions of tape. The number of revolutions depends on the thickness of the PTFE tape you are using. Swagelok PTFE tape is thicker than the average hardware store PTFE tape, so two to three revolutions is enough. If you are using thinner tape, you will need to apply more tape. Draw the free end around the threads tautly so that it conforms to the threads.
4. When you have wrapped enough tape, cut or tear off the excess tape. If the tape does not lie flat, firmly press the tape into the threads. Now tighten the male end connection into the mating female end connection. Then tighten the male end connection until wrench-tight.
Once the connection is tight, do not loosen it. Doing so could mean leakage at the pipe thread. That's all there is to it. (If you'd like to see a demonstration rather than just read instructions, click above in this post to watch the video.)
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