When installing gas pipes, what is needed on the threads.?

Teflon tape will do the trick, test with water when done. If you see any bubbles.. re do it.

You have to use a Teflon based paste or "pipe dope". That is code in all 50 states for gas installations. Do not use teflon tape. The tape is for water plumbing only and will not withstand the corrosivness of the gas and thusly you will get gas leaks. Check connections with soapy water or...contrary to the norm, u can check for a leak with a lighter...yes I said lighter. If you have a small leak it will stay lit just like a pilot light on a stove or water heater does. Now, if you have a humongous open pipe then no...dont use the lighter...lol

Teflon tape in the direction of the thread

Get pipe thread sealer, of TFE paste in the plumbing section. I wouldn't use the teflon tape for gas. "Why not the tape?" you ask. Well because I have seen alot of pipe fitters work and they don't use teflon tape for gases, I never asked them why but they are the pros.

And put some soapy water in a squirt bottle and snoop for leaks when you are done.

You can use the white teflon paste or teflon tape. I prefer the paste, higher specs for pressure. Also can be used for water lines too.

Tape or some kind of pipe dope. It both lubricates the threads and is a bit of a seal.

liquid teflon or teflon tape

u need to use teflon tape and pipe dope to ensure no leakage

Teflon tape. Don't overdo it.

they make a special teflon tape for gas, ask at lowes, home depot, etc....