Why does the Vatican have a lightning rod?
DO NOT replace your gas lines with Pex. Pex is designed for potable water applications only. You need to use either galvanized metal pipe or better yet, black iron pipe. You can easily fit together what you need with iron pipe and the right fittings. Seal all the joints together with yellow thread tape (as opposed to the blue thread tape for water). If you don't feel comfortable putting together a gas line (it can be quite dangerous) then call a professional who can. Remember, if your house is damaged because of you didn't fix your gas line correctly, your home insurance will not cover the damages.
I thought it was cool that Ultimate Warrior has an award named after him, good for Connor and his family that he's the first to receive that award.
NO!! Not approved by code for gas or any other hydrocarbon, gas or liquid. Black Iron, flaired K-copper, or gas-approved polyethylene are approved for gas lines. PEX is not. NOTE: Poly pipe is not approved for propane - just Natural Gas.
Not allowed in my area - only galvanized pipe - but you'll have to check local building codes.
We have black iron, CSST, or copper tubing only.