How to Create Leak-Proof Joints with Pipe Dope

What is pipe dope?

Thread sealant, commonly known as "pipe dope," is used on a pipe to help secure a seal between threaded connectors. It comes as either a paste or tape and helps fill the threads between the pipe and fitting.
When performing any plumbing project, choosing the right thread sealant is important. Whether you are a DIYer fixing a leaky shower head for the first time or a seasoned plumber needing a few reminders, here is how to create a watertight and airtight seal using pipe dope.

Choosing a thread sealant

There are a variety of dopes on the market today. A pipe joint compound should be selected based on pipe and fitting material compatibility, chemical compatibility, and temperature performance ranges. Let's take a look at the most popular pipe dopes offered by Oatey:

Can of Hercules Pro Dope Pipe Dope

●    Pro Dope

Hercules® Pro Dope® is a versatile thread sealant paste that is lead-free and nontoxic. The oil-based compound is easily applied with a natural bristle brush and does not drip. Pro Dope prevents rust and inhibits corrosion by forming a protective coating on threads. It is non-hardening, and the sealed joints can be disassembled without damage to pipe fittings or threads.

Pro Dope is FBC™ System Compatible and is tested and monitored on an ongoing basis to assure its chemical compatibility with FlowGuard Gold®, BlazeMaster®, and Corzan® piping systems and products made with TempRite® Technology.

Can of Hercules Megaloc

●    MegaLoc

Hercules® Megaloc® is a multi-purpose thread sealant that creates a stronger seal by adding Kelvar into the advanced pipe joint compound formula. These individual strands of Kevlar are mixed into the compound during the manufacturing process and as the threaded joint is being assembled, these strands are compressed into the root of the threads, creating the best possible seal in the market today.  Its odorless formula is non-separating, non-flammable, and non-hazardous, and it resists hardening and cracking.

●    Great White

Can of Oatey Great White

Oatey® Great White® Pipe Joint Compound With PTFE is a white-colored, non-hardening, non-separating, nontoxic paste that lubricates and seals all threaded joints. This compound permits a tighter assembly with lower torque for secure permanent sealing of all threaded connections. Allows for easy disassembly without stripping or damaging threads.

Great White is also FBC™ System Compatible and is tested and monitored on an ongoing basis to ensure its chemical compatibility.

Please refer to our website to check compatibility and view our full line of thread sealant paste.

What can it be used on?

Our versatile sealants can be used on pipe and fittings made of:

  • Black iron
  • Galvanized steel
  • Copper
  • Brass
  • Aluminum
  • Stainless steel
  • Many others*

*For special applications that may not be covered in this or other Oatey literature, please contact the Oatey Technical Services Department or visit our technical database website at

Oatey pipe dopes can be used on lines carrying natural gas, air, steam, hydronic heating, ammonia, brine, diluted acids, sprinkler systems, and many more. Be sure to check the pressure rating for liquids and air/steam before applying.

Oatey thread sealant products are soft set and do not have a cure time. As soon as the system is put together, you can start to use it. You can easily apply pipe joint compounds with a natural bristle brush.

How to apply pipe dope or thread sealant tape

When applying a pipe joint compound, remember that you are filling the thread openings, so using the mixture in the same direction as the threads will sometimes lead to poorly filled joints. Brushing across the threads will provide better coverage and will ensure that you always fill the threads.

Pipe Dope In Use

Make sure to clean all pipe threads. Be sure all joints are free from rust, scale, grease, and other contaminants. Remove any debris with a clean cloth or wire brush. Stir contents thoroughly and apply evenly to male threads.

You can also use Hercules Megatape, an all-purpose PTFE thread-sealing tape designed for threaded pipes. Wrap it clockwise around the male thread first, then add the thread sealant. The thread sealant will fill any gaps caused by tape failures and ensure a proper seal. Watch this video to learn how to apply PTFE thread sealant tape properly.

Hercules MegaTape in Use

If you need to remove the sealant for any reason, we recommend wiping it off with a rag and using a wire brush to scrape between the threads. You can also use soap and water or a vinegar-and-water mixture to clean the joint further.

Cautions when using

Before applying any thread sealant, we recommend checking to ensure your system — and whatever material was used to make it or can be found in it — is approved and compatible with the thread.

You can find that information on the thread sealant container or check with the manufacturer. Almost all Oatey thread sealants carry an NSF 61 rating, which means they are safe to use with potable water.

When to call a plumber

If you used pipe dope to stop a leak, but it's still there, you may have accidentally cross-threaded the pipes. You should not continue to add more material. Instead, it's best to call a plumbing professional to fix the connection.

In addition, if the thread was dirty and was not cleaned properly, the pipe dope may not have compacted into the thread properly. A professional will need to assess the issue.

Now that we have explored best practices when using pipe dope, you are ready to seal and properly provide a leak-free connection.

Related Resources


How to Use Hercules MegaTape Thread Sealant

Leak Detector Product Overview