WNTU4 wrote:
"Now I know I can`t attach ground to gas line."

The gas line is likely grounded on the house side of the meter. Stoves,
etc. have e3lectrical appurtenances which otherwise might shock you..

The supply side of the meter is likely nominally insulated to avoid
overloading the cathodic protection rectifier which maintains a fraction
of a volt on steel pipes and other gas supply equipment. This tiny
potential ensures that ions flow toward the apparatus rather than away,
which would erode the stuff away.

You only must avoid shorting out the cathodic protection potential. Easy
since its insulation is already very poor. Pipe dope has cracks. The
rectifier has a large ground bed for its return. The rectifier has leaky
arresters, etc. It`s no real problem to have a very near ground rod. The
gas pipe is subjected to plenty of lightning current during
thunderstorms.

Best regards, Richard Harrison, KB5WZI