Just an added note to those above. Using good quality flare nut wrenches increase the chance of success in separating these pieces, with reduced chance of damage to the hex heads on both parts. If you go Joe H's route and cut the fuel line to use sockets to remove the big inlet fitting and separate the flare nut from the fitting, 6-point sockets will also lessen the chances of damaging either piece during disassembly.
Sounds like a good excuse to add to your tool box if they're not currently on-hand.
