Ground to a gas line?
Are you reading this page because you want to know if it is OK to ground electrical equipment to an existing gas line?
Ground to a gas line? No! Never!
Don't even THINK about using a gas line as an electrical ground strap.
Metal underground gas piping is never approved as a grounding device.
It's against the NEC National Electric Code 250.52(B), The UPC Plumbing Code and The NFPA Fire Code.
If that isn't enoungh, it's dangerous and stupid.
Get it ? NO!