What should be used to protect buried piping and underground tanks?

The use of corrosion-resistant coatings for buried piping and underground tanks is essential due to the underground environment's potential for moisture, soil chemicals, and varying temperatures that can lead to corrosion. These coatings provide a protective barrier that helps prevent rust and deterioration of the materials, thus prolonging the life of the piping and tanks.

Corrosion-resistant coatings are specifically designed to withstand the chemical and physical conditions typically found underground. When underground storage systems and piping are subject to such harsh environments, applying these coatings is a standard best practice to ensure safety and compliance with regulations.

The other options, while they may offer some level of protection in certain scenarios, do not provide the same comprehensive defense against corrosion as a corrosion-resistant coating does. For example, paint may not adhere or withstand underground conditions effectively, thermal insulation is more focused on retaining temperature rather than protecting against corrosion, and aluminum sheets may not provide adequate long-term protection in a corrosive environment. Thus, the best choice for safeguarding buried systems is the application of corrosion-resistant coatings.