Plumbers Tape For Your Project

When someone says plumbers tape, they usually mean one of two things. One is a roll of galvanized metal strip with holes in it. That is really a plumbers strapping tape. If the plumbers tape you're looking for is the thin white film tape, that's Teflon® tape.

Teflon tape is a great invention, and I wouldn't be without it. But I do see it being used in ways that are pretty useless, and even counter-productive. Here's a few tips from the Plumbing Geek about how and where to use Teflon® tape, and where not to use it.

When to use Teflon® Tape

There are many different types of pipe joints that are used in plumbing and mechanical systems. Of all the different kinds, there is only one type of joint that it is proper to use Teflon tape on. That is iron pipe thread, or what is referred to as a tapered thread.

Tapered threads, when tightened together, seal all along the engaged threads. The plumbers tape acts as a lubricant to allow unimpeded penetration, and as a seal to fill any voids that remain after the desired torque is reached. For the most part these same joints may be sealed with a good joint compound like Megaloc.

Sometimes the use of thread compound isn't recommended by the manufacturer. In those cases, Teflon® tape is a great tool. The reason Teflon tape is great for a DIY plumber is because it remains fresh and easy to use after years in the tool box.

How To Apply Teflon® Tape

  1. Lay the end onto the lead threads of the male thread you're going to install.
  2. Hold your thumb on the end of the tape and draw the tape taut around the pipe in a tightening direction.
  3. Draw the tape down into the thread as you turn the fitting.
  4. After three or four wraps break it off by pulling.
  5. Smooth the end down with a finger and assemble the joint.

Best ways to seal other types of plumbing joints

  • To seal garden hoses, use rubber hose washers.
  • Hot water heater flex supplies seal best using the washers that they come with. Make sure they're bottomed out in the nut before you start the thread, or they may “lip up“ and become deformed.
  • Compression joints using brass ferrules seal with joint compound.
  • Compression joints using rubber or neoprene are put together dry, using brass friction washers when available.
  • Never put anything on an “O” ring except grease. O rings are made of neoprene and are fairly new technology, I like faucet stem grease, also known as heat proof grease, for them.
  • Gasket unions such as dielectric unions go together dry.
  • Unions and ground joints get joint compound on their faces, including the point where the ring spins on the lip it draws down, and threads.
  • Flair joints are not found much in plumbing, with the exception of gas flexes. I have put them together dry, and with joint compound. What I will usually do is wipe a very light smear of joint compound on the sealing surfaces with my finger. Always be conservative around gas pipe joints so you don't clog a gas jet.
  • Slip joints are compression joints, use nothing but friction washers at rubber slip joints, and toilet wax on nylon cone washers.

Now you know when to use Teflon® tape, and what to use instead when it's not the appropriate product. Here's to knowing the right tools and plumbing supplies for all the jobs you do! 

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