My heating company recently installed the propane tank and ran the line to the fireplace. Everything has been pressure tested and approved. I would like to install the burner and logset but I am unable to remove the plug at the end of the galvanized joint. This is where I need to attach the flex line for the burner plate. Would the flex line normally go where the plug is with some sort of adapter or should the galvanized union be removed completely and hook the flex line directly up to the incoming copper? Never done this before so apologize if it’s a dumb question. Thank you.