What's the current standard for Gas pipe. It used to be black iron. Has that changed?
Black iron is good for indoor applications. There is a flexible pipe available as well. It comes in rolls and you cut it to the desired length and use compression fittings to connect. I used it in my house a dozen or so years ago and haven't had any problem with it.
For underground applications you can use either Scotchcoat which is black iron with a green coating or polyethelene.
Thanks Des. I'm working out the final plans for cooking, refrigeration and on demand hot water as a backup to the solar HW.