Teflon tape is not recommended for use on gas lines because it is not designed to withstand the high pressures and temperatures that are typically found in gas systems. Teflon tape is a thin, flexible material that is commonly used to seal threaded connections in plumbing applications, but it is not suitable for use in gas applications where leaks can have serious consequences.
Instead, gas lines typically use sealants that are specifically designed for use with gas systems. These sealants are formulated to withstand the high pressures and temperatures of gas systems and provide a reliable, long-lasting seal. Common sealants used in gas applications include pipe dope and thread sealant paste.
It is important to use the correct sealant for gas lines to ensure that the system is safe and leak-free. If you are not sure what type of sealant to use on your gas lines, it is best to consult a licensed plumber or gas fitter for guidance.