I am installing a vented gas insert into a masonry firebox. I have to drill into the firebrick and block wall to get to the main gas line which is on the other side of the wall. Is it safe to use flex line through the firebrick and block to get to the gas line?

In some areas flex line is not to code. If it's approved in your area then go for it. My suggestion, though, would be to "hard pipe" it using standard galvanized piping.

Hi mp, Rick is right about the "hard pipe" being best, but you never want to use "standard galvanized piping" , use black pipe for gas line. good luck

Hi mp, Rick is right about the "hard pipe" being best, but you never want to use "standard galvanized piping" , use black pipe for gas line. good luck

Yes. The "hard line" is "standard"... but typically it's black. Standard hard line for gas.

Do NOT use the same galvanized that you would for water lines.