How to Seal Stainless Steel Pipe Threads

Stainless steel pipe threads are protected by sealant in order to prevent leakage, contamination and weathering. Sealing stainless steel threads also provides lubrication for easy assembly of male and female end connections. Pipes can be sealed using TFE tape or an anaerobic pipe dope or sealant. TFE tape has proven to be the more popular selection due to its convenient, simple, mess-free application.

  1. Select a TFE tape based on tape density and thickness, which determine its ability to seal. Tape with 3-4mm thickness and a density of 1g per CC is most often recommended.

  2. Start with the first thread on the male pipe. Wrap the TFE tape clockwise, in the direction of the thread spiral. The tape should not overhang the first thread, or it could contaminate the system.

  3. Draw the remaining end of the tape tightly around the threads; it should conform to the threaded surface.

  4. Press the TFE tape firmly at the overlapping points. Secure the tape into the threads using your thumbnail if it does not lie flat; then proceed to connect the male and female pipes.

  5. Apply a liquid sealant as an alternative. This pipe dope is effective for temperatures of -65 to 350 degrees F. Ensure that both threads, male and female, are free of grease, oil or other contaminants that can trap air.

  6. Squeeze enough of the dope to seal the first two male threads, in a full 360-degree application. Use a dry rag to wipe off any excess sealant after the pipes have been connected.