Most valves, nipples, and fittings are designed to use Teflon tape to form a leak-free seal. However, depending on the products that you are using, some Teflon tapes work better than others.
STAINLESS STEEL VALVES AND FITTINGS
For example, with stainless steel threads if you use standard, plain Teflon tape or Pipe dope you will run the risk of the threads seizing prematurely. It can happen very quickly where when you’re tightening an elbow the threads seize before they are tight enough to seal. When this seizing happens to soon, it likely seizes in an unusable position.
This issue happens with stainless steel because it is a harder substance than, for example, brass.
The solution to this problem is to use anti-seize nickel-filled PTFE tape for a thread seal. Apply the ½” or ¾” Teflon tape by wrapping it clockwise around the threads for 3-6 wraps.
It is important to wrap it clockwise because that is the direction that the pipe or fitting will be twisted when you connect it. Twisting it on counter-clockwise can cause the tape to come undone.
Leave one thread at the end unwrapped so that the overhanging Teflon tape doesn’t tear off and flow through as this could cause problems with the valve down the line.