Copper piping is code approved for gas water heaters only if what condition is met?

Copper piping is approved for gas water heaters specifically under the condition that there is no sulfur in the gas. Sulfur present in the gas can lead to the formation of corrosive compounds when it interacts with copper. Over time, this corrosion can significantly weaken the integrity of the copper piping, potentially leading to leaks or failures. Therefore, ensuring that the gas supply is free from sulfur is crucial for the safe and effective use of copper piping in gas applications.

The other options do not address the key concerns related to the chemical interactions between copper and components in the gas. Newness, the method of soldering, and insulation do not fundamentally mitigate the risks associated with sulfur compounds. Thus, the regulation focuses on the composition of the gas rather than the material conditions or installation methods.