Pipe sealant: Everything a homeowner needs to know

Many types of metal pipes are joined by screwing them together, forming a tight seal. However, leaks can sometimes develop with age, corrosion, or vibration. This is especially true with industrial applications but it can also happen around the home. The simple answer is to use pipe thread compound when joining pipes and fittings.

This inexpensive product is applied to the pipe threads before they are screwed together. It seals the threads, preventing leaks and corrosion. In some applications, pipe thread compound also keeps the pipes or parts from slowly loosening due to vibration or stress.

Using pipe sealant whenever joining plumbing fixtures is a great way to protect your home and save on costly repairs from the water damage caused by leaking pipes.

A quick word about the various types of pipe sealants: both tapes and compounds are suitable for sealing pipes. One of the most commonly used solutions is plumber’s tape. Pipe thread compounds (sometimes called pipe dope) have a paste-like consistency and are brushed onto the threads.

For most small applications, plumber's tape is sufficient. This widely available tape is simply a non-adhesive white tape wrapped around the threads before screwing the pipe into the next section. Make sure to apply the tape in the direction of the threads. An easy way to remember this is to wrap the tape clockwise if you are looking into the end of the pipe.

Plumber's tape has some disadvantages. First, it is not a true sealant because it doesn’t adhere to the threads; it simply fills the gap between the two surfaces. Also, the tape can tear as the pipes are joined together or tightened later and won’t create a secure seal if subjected to high pressure.

Liquid pipe sealants generally do a better job at sealing the threads. Make sure to read the label and choose one compatible with the type of pipe you are using. Look for a sealant that will not crack or become brittle. If the lines are to contain potable water, ensure that the pipe thread compound is suitable.

To apply:

1. Make sure the pipe threads are clean and free of grit.
2. Brush some of the pipe sealant onto the threads before joining them.
3. Always apply the pipe sealant to the pipe threads and not inside the fitting for the pipe. This would result in the sealant getting inside the pipe.

Thread lockers can often be used as an alternative to pipe sealants, putties, and plumber's tape. They come in various strengths and have the advantage of being an adhesive that prevents the fitting from loosening with vibration or temperature change. Many plumbers use Loctite 222 Threadlocker for its quick cure time and corrosion protection. Although it forms an excellent seal and prevents loosening, the fitting can also be easily removed with hand tools when necessary.