I always go back to the NHRA rule books. They made safety top priority and really stressed fuel system safety. Compression fittings have no place on a car, Period!

Our School bus lot has CNG fuel lines run above ground for 400 feet or more with a compression fitting every 10 or 12 feet. There are hundreds of them in the fueling system all holding 3600-3800 psi. They are stainless on stainless and made for the job, but I still wouldn't run them on a gasoline system.