Natural gas does not [itself actually] corrode anything, including copper. Corrosion is a chemical reaction between metal and oxygen. It is the oxygen in the normal air that is mixed in with the gas that would cause any corrosion. The corrosion may also be accelerated by heat and moisture.

What will corrode copper?

The presence of oxidizing acids; heavy-metal salts, sulfur, and ammonia; and a number of sulfur and ammonia compounds can cause corrosion to set in. Water that comes from a well is much more likely to contain these materials and put copper lines in jeopardy—but it can occur in the civic water system as well.

Can you use copper tube for gas?

Copper pipes are commonly used for a gas line for water supply lines in the manufacturing industry and for refrigerant lines in HVAC (heating, ventilation, cooling and air conditioning) systems. Copper tubing may be rendered as soft or strong copper which has outstanding corrosion resistance which stable connections.