This sulfur is probably what attacked your copper line. A. Copper is ok, flare fittings are best. Black steel is best indoors but no one wants to work anymore so they have this new stuff called track pipe. A. Copper pipe, or tubing is NEVER ALLOWED BY CODE IN THE US FOR NATURAL GAS DISTRIBUTION!
Consequently, can you use a compression fitting on a plastic pipe?
Connection to compression fitting. Many, but not all, compression fittings are suitable for use with plastic fittings and pipe. When using compression fittings with Speedfit pipe, a Standard Pipe Insert (prefix TSM) must be used to withstand the compressive pressure of the olive.
Can you use PTFE tape for gas?
If you use plumber's Teflon tape on gas pipe fittings, the tape will degrade over time and gas vapors will escape from the fitting. Plumber's Teflon is white in color and thinner than yellow gas-rated Teflon tape. Leaking gas pipes and fittings are dangerous and can cause an explosion.
Can you use brass fittings on a gas line?
Galvanized steel, copper, brass or CSST (Corrugated Stainless Steel Tubing) also can be used in some areas, but some utilities specifically prohibit the use of copper. Steel piping typically is black with malleable iron or steel fittings. Galvanized steel is used in some areas as well.