Pipe Joint Compound vs. Pipe Thread Sealant

The threaded end of a black iron pipe and a pipe wrench.

If you need to do a plumbing job in your home, you will normally have a choice between pipe joint compound (pipe dope) and a pipe thread sealant tape (Teflon tape) when making an airtight seal in the pipes and connection fittings. There are advantages to both; however, there are times when you will need to know which type of seal to use in a given situation. This article will try to explain the differences in the two types of sealants and when you should use each.

Pipe Joint Compound

A pipe joint compound is an adhesive type mixture that can be clear in color or look like white putty. It is usually applied to the threaded end of pipes to produce an airtight seal that prevents water leaks. Pipe joint compound may also be referred to as pipe dope or even pipe glue. In fact, pipe joint compound used for PVC pipes and connection fittings is often referred to as simply PVC glue.

Pipe joint compound is usually applied with a brush, small piece of wood, or even by hand. It is applied on the threaded end of pipes and also on the inside of connection fittings before the two pieces are attached to each other. Over time, the adhesive dries and expands ever so slightly creating an airtight seal between the pipe and connection fitting where the compound has been applied.

Generally speaking, pipe joint compound creates a more durable and airtight seal than pipe joint sealant tape. In fact, most professional plumbers use pipe joint compound for pipe and fitting connections that are considered to be permanent. A good example of this would be a gas or water pipe that is buried underground or is run beneath your home. Since the chances that these pipes will be disconnected from the connection fitting are slim, it is considered a permanent connection. For lasting connections, pipe joint compound is a much better choice than Teflon tape.

Pipe Thread Sealant Tape

Pipe thread sealant tape, or Teflon tape as it is more commonly referred to, is a type of pipe sealant that comes on a roll that is similar to electrical tape or masking tape. Teflon tape comes in a variety of thicknesses that make it more or less suitable for certain installations. In some areas, Teflon tape can be used in place of pipe joint compound if the thickness of the tape has been approved for use for a specific type of plumbing applications. Teflon tape is applied by wrapping around the threaded end of a pipe or fitting.

However, most professional plumbers tend to shy away from Teflon tape for permanent connections. Instead, they will use it for projects that may occasionally need to be replaced or disconnected. For example, consider the water lines that supply water to your bathroom sink or toilet. If you look at the shutoff valves, you will notice that the shutoff valve and water supply lines are sealed with Teflon tape. This is because these types of connections are often the source of leaks in the bathroom and may need to be replaced. If the connections were made with pipe joint compound, it would be much more difficult to remove the fittings and replace them. However, with Teflon tape, it is easier to remove bad parts to make the repairs needed.