I just got e-mail about this subject from a friend who just retired from the So. Cal. Gas Co. He started at the bottom, and has plenty of experience with gas fittings. This was his main reply "As far as I can remember, the white Teflon tape won't eat away or affect the fittings that you put it on, another words it's safe. It's been fine on all my fittings that I have LP connected to as well as water and natural gas. Yellow anything, pipe, fittings or marking in the streets, is just a national standard to ID gas ( Natural or LP )". Thst's good enough for me on this subject. Next...