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wikiHow to Use Teflon Tape

Three Parts:Taping ThreadsUsing Pipe Dope on Top of TapeUsing Products CorrectlyCommunity Q&A

Teflon tape is used to reduce the risk of leaks when connecting metal pipes along plumbing or fuel lines. Wrapping one pipe’s male threads in tape creates a smoother surface with more lubrication, thus allowing it to reach further into the second pipe’s female threads. For extra assurance, liquid sealant can also be added to the tape’s surface before connecting the two pipes. Although “Teflon” is technically a brand name that is now used universally much like Band-Aid, any tape labelled “PolyTetraFluoroEthylene” or “PTFE” will suffice.[1]

Part 1
Taping Threads

  1. 1
    Wash the threads. Wipe them with a cloth. Remove dirt, grime, or any other materials that may impede a tight connection. Clean both the male threads of one pipe and the female threads to the other.[2]
  2. 2
    Check the threads’ direction. Most pipes’ threads run in a clockwise direction, but there are exceptions to this rule. Always check which way the grooves run before applying tape. If you can’t tell with a glance, fit the male end of one pipe into the female end of the other. Mark which way you need to turn the male end in order for it to screw into the female.[3]
  3. 3
    Wrap the end of the male threads. Line up the edge of the tape with the outer edge of the threads perfectly. Make sure no amount of tape projects over the pipe’s edge. If it does, peel the tape off of the threads, trim the used strip from your roll, and try again. Cover the pipe’s edge with one layer of tape, following the direction that the threads run (clockwise or counterclockwise). Once you complete a full circuit, wrap a second layer of tape over the first.[4]
    • Stray bits of tape that stick over the pipe’s edge will end up in the pipeline when the two pipes are connected. They may then block the flow of water or gas, causing clogs and/or weak pressure.
    • Pull the tape taut as you unroll it to ensure a tight fit. The tape should be drawn in between the threads as you wrap them.
  4. 4
    Continue wrapping inward. Follow the direction of the threads as you go. Wind the tape over them so that half of it covers the preceding layer while the other half covers the bare threads. Pull the tape taut as you do so to make sure that both the grooves and ridges are equally covered. Once the threads are totally covered, cut the tape loose from your roll and pull the end tight over the last threads.[5]
    • If you tape the threads counter to their direction, the other pipe’s female threads may dig the tape out of the grooves when you screw the two ends together.
  5. 5
    Double-check your work. Make sure that you have covered the entire length of the threads with consistently tight tape. Inspect their grooves and ridges to confirm that their shapes are perfectly visible and unblemished by loose tape. Unwrap the tape and start over with a new strip if the original tape appears loose at any point. Otherwise, screw the two pipes together.[6]

Part 2
Using Pipe Dope on Top of Tape

  1. 1
    Determine whether pipe dope is prefered. Expect the addition of pipe dope to create a more permanent seal. Only add it to your layer of Teflon tape if you are confident that you will never have to separate the pipes in the future. Use Teflon tape by itself in any areas where you are likely to replace and/or alter pipes and fixtures, such as in the shower, bathtub, or sink.[7]
    • Additionally, avoid using pipe dope for lines carrying drinking water. Use Teflon tape by itself to eliminate the risk of contamination by liquid sealants.
  2. 2
    Tape the male threads. Before using pipe dope, apply Teflon tape just as you would if tape was all that you were using to make your seal. First, wash both the male and female threads to remove dirt. Then tape the male threads, beginning with a double layer around its outer edge before moving inward, following the threads’ direction as you go. Inspect your work to make sure that the tape has conformed to the shape of the threads’ grooves and ridges perfectly. If necessary, remove the original tape and begin again with fresh tape.[8]
  3. 3
    Apply pipe dope. Many liquid thread sealants will include a brush in their cap, like a medicine bottle’s dropper. If yours doesn’t, dab a fine, thin brush with pipe dope. Apply a thin, even layer directly to the taped male threads. Then screw the two pipes together immediately, before the pipe dope has a chance to dry.[9]
    • Although this is a popular way of reinforcing pipe seals, there is some debate over whether or not the added pipe dope actually makes the tape’s seal any stronger.[10]

Part 3
Using Products Correctly

  1. 1
    Create a safe work environment. Shut off the water or gas before disconnecting any lines. Also shut off the electricity in the immediate area to prevent electrical shocks and fires. If you are working on a gas line, be sure to have a functional gas detector on hand and learn how to operate it before starting work. Improper gas seals may lead to poisoning, fire, or other hazards. If you have little to no experience in working with water or gas lines, hire a professional to avoid personal injury and property damage.[11]
    • Additionally, always test the lines after completing your project. Do so before you begin to put everything back in place so you still have quick and easy access to the pipes in the event of a leak.[12]
  2. 2
    Follow color-coding. Always use yellow Teflon tape for gas-lines, since this yellow tape is specifically for that purpose. For waterlines, use pink tape for best results. White tape is also acceptable for water lines whose pipes have a ⅜” diameter or less, but favor pink over white in general, since pink tape is of a higher density. For oxygen lines, only use green tape.[13]
    • White tape is cheaper for a reason. Its low density often necessitates using more tape to achieve the same tight seal as a high-density product. It is also more prone to tearing, with stray bits ending up inside the pipe and potentially causing blockage.[14]
    • Pipe dope also comes in water- and gas-specific varieties.[15]
  3. 3
    Read the directions. Check if the instructions recommend covering the threads with a specific number of layers. The number may vary according to the product’s materials and density. Do not exceed the recommended number, since this may cause a loose seal when the extra tape bunches up during screwing.[16]
    • Few if any tapes require more than three layers, since this is generally too thick for a proper seal.[17]
  4. 4
    Apply tape to correct minor flaws only. Keep in mind that Teflon tape is only meant to create a smoother surface for threads’ suffering from teeny tiny micro-abrasions. Do not connect pipes with missing or broken threads. Buy a new pipe instead, or have the original re-threaded.
  5. 5
    Install a dielectric union to connect pipes made of different metals. Expect pipes made of different metals to corrode over time if they are screwed together directly. Do not trust Teflon tape to act as an adequate barrier between the two materials. If you are connecting two different kinds of pipes, purchase a dielectric union to join them without bringing them into direct contact.[18]
  6. 6
    Use tape on NPT and NPTF threads only. Recognize a standard National Pipe Thread (NPT) or National Pipe Thread Fuel (NPTF) by their tapered threads. The tapering forces two pipes to pull together as you screw one’s male threads into the other’s female end. Use Teflon tape or other sealants on these to correct the micro-flaws caused by mass production. Do not use tape to seal the following types of threads:[19][20]
    • AN (Army/Navy)
    • BSPT (British Standard Taper Pipe Thread)
    • GHT (Garden Hose Thread)
    • NPSI (National Straight Intermediate Pipe)
    • NPSM (National Pipe Straight Mechanical)
    • NST (National Standard Thread)

Community Q&A

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  • Plastic or PVC piping does not require tape or other sealants.[21]
  • Teflon tape, pipe dope, and gas detectors are available online and at hardware and plumbing stores.

Sources and Citations

  1. http://allthumbsdiy.com/plumbing/when-to-use-ptfe-teflon-yellow-or-white-tapes-or-pipe-dope
  2. http://www.acmehowto.com/plumbing/general/teflon-tape.php
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Article Info

Categories: Piping | Faucets and Taps

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