PEX pipe is not approved for use with natural gas or propane. PEX pipe is
typically used for potable water systems, radiant floor heating, and some other
non-pressurized applications. It is not designed to handle the pressures and
chemical properties of gases like natural gas or propane.
For gas lines, materials such as black steel pipe, copper, or corrugated
stainless steel tubing (CSST) are commonly used and are specifically rated for
gas service. Always follow local building codes and regulations for the proper
materials to use when installing gas lines, and if in doubt, consult a licensed
professional.