Which type of product piping requires cathodic protection?

The correct choice relates to single-walled steel tanks, which require cathodic protection due to their vulnerability to corrosion. Single-walled steel tanks are more exposed to environmental factors, including moisture and soil conductivity, which can lead to rusting and deterioration over time. This is particularly critical when such tanks are used for storing flammable liquids or hazardous materials, as leaks resulting from corrosion can pose significant safety and environmental hazards.

Cathodic protection is a technique used to control the corrosion of metal surfaces by making them the cathode of an electrochemical cell. This method is necessary for single-walled steel tanks, as it helps to extend their life by preventing corrosion that can occur from the soil or other external sources.

In contrast, double-walled steel tanks typically have an outer layer that provides an additional level of safety and protection against leaks, thus reducing the immediate need for cathodic protection. Plastic and copper tanks are not typically at risk of corrosion in the same manner as steel tanks, which is why they wouldn't require such protection. Plastic tanks are generally resistant to rust and corrosion, while copper tanks may develop surface oxidation but do not require cathodic protection in the same way as steel.