How do I loosen a stuck threaded brass fitting?

Written by sal marco
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How do I loosen a stuck threaded brass fitting?
Removing brass fittings can require some extra muscle. (plumbing image by Inger Anne Hulbækdal from

Brass fittings, primary used on hot or cold water lines to connect one piece of pipe to another, become stuck due to corrosion or over-tightening. Sometimes loosening a stuck brass fitting is as easy as turning the locknut counterclockwise to tighten it further and then turning clockwise to loosen. Oftentimes, methods that are more complex are required in order to remove the fitting.

Skill level:

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Things you need

  • Penetrating oil
  • Rag
  • Adjustable wrench
  • Brass hammer
  • Scrap wood
  • Fire-safe cloth
  • Heat gun or propane torch

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    Penetrating Oil

  1. 1

    Wipe the fitting with a clean, damp cloth to remove dirt and dust.

  2. 2

    Spray penetrating oil onto the locknut and fitting.

  3. 3

    Allow the penetrating oil to sit for five to 10 minutes.

  4. 4

    Wipe the excess penetrating oil away with a rag.

  5. 5

    Place an adjustable wrench over the locknut and turn in a counterclockwise direction to loosen and remove the brass fitting.


  1. 1

    Brace the fitting against a secure surface such as the wall, floor or a piece of wood.

  2. 2

    Tap the fitting several times with a brass hammer to loosen any debris on the fitting threads.

  3. 3

    Fit an adjustable wrench over the locknut and turn in a counterclockwise direction to release the stuck fitting.


  1. 1

    Sweep the area surrounding the brass fitting clean of all dust, dirt and debris.

  2. 2

    Place fire-safe cloth on the floor or wall near the brass fitting to keep from burning the floor wall or starting a fire.

  3. 3

    Heat the locknut on the fitting with a heat gun or propane torch. Keep the heat source in constant motion, moving back and forth over the fitting. Do not allow the flame from the propane torch to remain in one area because you will permanently damage the fitting.

  4. 4

    Grip the locknut with an adjustable wrench and turn the locknut in a counterclockwise direction to loosen.

Tips and warnings

  • Alternate between applying penetrating oil to the fitting and tapping the fitting with a hammer to loosen the fitting.
  • Consider cutting the pipe at each end of the fitting and replacing it if the brass fitting is highly corroded or these methods are unsuccessful.

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