How do I remove a gas control valve on a water heater?

Not particularly a DIY project. If the valve is bad and the heater is more than 5 years old, replace the heater. Fairly simple task but with big consequence if done wrong, gas is nothing to fool with. Turn the gas off, drain the heater, remove all lines to the valve and put a big pipe wrench on the valve and unscrew it. I have only seen 1 gas valve that needed to be replaced and it was under warranty. Personally I would not do this job except for myself. There are some posts on You Tube.