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Teflon tape and Securing that Fitting Safely with the RIGHT Tape, it is not a guess!

Terry Penney

When it comes to TEFLON Tape (plumbers tape) for fitting most people would just pick up a roll at your local supply store and head out, and wonder latter why did it fail or not work right!   The different types are  not common to a lot of folks but the usage is as difference as a crescent wrench and a jack hammer.   Yes both are tools but that about the similarity. Some type of pipe thread sealant are not the same, but reaching for the nearest pipe joint sealing material can lead to serious problems, including leaks, pipe system damage, contamination, and plant downtime. The purpose of this white, nonsticking tape is to serve as a lubricant when threaded parts of a piping system are being assembled. The inherent slipperiness of the material makes assembly easier.

Strictly speaking, Teflon tape is not a thread sealant. The tape may have the effect of clogging the thread path, but it does not actually adhere to surfaces as a true sealant should.

At work or at home we use, “Teflon tape”

  • First, the lubricant qualities allow male threaded pipe to be turned deeper into female threaded fittings to prevent leaks;
  • Second, it acts as a filler to smooth out micro abrasions or surface irregularities on threads;
  • Third, it keeps the male and female threads from rusting together (a.k.a. seizing);

Thread seal tape (also known as PTFE tape or plumber’s tape) is a polytetrafluoroethylene (PTFE) film for use in sealing pipe threads. The tape is sold cut to specific widths and wound on a spool, making it easy to wind around pipe threads. It is also known by the genericised trade-name Teflon tape; while Teflon is in fact identical to PTFE, Chemours (the trade-mark holders) consider this usage incorrect, especially as they no longer manufacture Teflon in tape form Since many provincial/ state and local codes adopted the use of double density tapes when making connections for natural gas, the use of same color for two different thickness presented a challenge when time came to inspect a job. Thus, a “yellow TEFLON tape” was later introduced for such application.

ASTM has broadened the specifications for PTFE tape colors:

  • White – used on NPT threads up to 3/8 inch
  • Yellow – used on NPT threads 1/2 inch to 2 inch, often labeled “gas tape”
  • Pink – used on NPT threads 1/2 inch to 2 inch, safe for propane and other hydrocarbon fuels
  • Green – oil-free PTFE used on oxygen lines and some specific medical gasses
  • Gray – contains nickel, anti-seizing, anti-gailling and anti-corrosion, used for stainless pipes
  • Copper – contains copper granules and is certified as a thread lubricant but not a sealer

Overuse or misapplication of thread tape may be a hazard. Excess application of PTFE tape can prevent mating threads from fully engaging, reducing the shear point of the threads. Combining thread-seal tape with a pipe dope compound can also overload threads. Also, internal overhangs of loose material may constrict a joint or slough off and form a foreign body that could jam a valve seat. Therefore, use of PTFE tape as a thread sealant is generally not considered appropriate in fluid power (hydraulic) systems

Advantages . Teflon tape can be applied quickly with no mess. It supplies sufficient lubrication to enable pipe system components to be easily assembled without damage to threads. The product is easy to carry and store, and has an indefinite shelf life.

Disadvantages . Teflon tape does not adhere to thread flanks, and does not provide a secure seal. Because the tape is thin and fragile, it is prone to tearing when pipes are being assembled and tightened. Bits of torn tape can migrate into a fluid system, clogging valves, screens, and filters. Teflon tape may be dislodged during pipe adjustments, allowing leak paths to form.

Ok how did the company tell you how to apply it!

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.

  1. For this exercise, let’s assume that our elbow piece is a RIGHT HANDED thread;
  2. That means when you are looking directly at it, the threaded piece is designed to be tightened by turning right;
  3. While looking directly at the elbow as if you are still installing it, visualize a thread sealant tape is wrapped in the OPPOSITE direction;
  4. For example, a sealant tape is wrapped to the LEFT TURN for a a RIGHT HANDED thread;
  5. 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;
  6. 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);
  7. 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.
  8. Hold down the beginning of the tape with your left thumb;
  9. With your right hand, gently tug on the tape until you can see the outlines of threads;
  10. You can let go of your left thumb once you complete the first turn
  11. Continue to tug on the TEFLON roll and complete 2 additional turns and cut it off
  12. 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)
  13. 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)

Like all things in Safety remember these items before applying


  • The main purpose of a thread seal tape / liquid thread sealant is to seal out micro abrasions or surface irregularities on threads. If you have a major gash or nick on a thread, you will need to replace the pipe section or re-thread it, rather than applying a thicker seal tape layer;
  • Applying more than 3 layers of sealant tape is not recommended;
  • When starting out, make sure the seal tape is not covering the pipe opening. Any exposed seal tape may break loose over a period of time and cause a blockage problem; in the future;
  • Pipe connections generally turn clock-wise but there are instances when that is not true (i.e. gas pipe union joint). Always test out and make a note of the pipe rotation before applying the tape and remember that the tape application must “go with the flow”;
  • You cannot connect dis-similar pipes together (i.e. copper-to-steel) and hope that a thread sealant tape will prevent from interacting with each other, possibly causing corrosion problems. In this situation, you must use a dielectric union .
  • If you need a gasket sealer, you may want to checkout can use hyolomar based


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