Are above-ground storage tanks typically pressurized or nonpressurized?

Above-ground storage tanks (ASTs) can indeed be either pressurized or nonpressurized, making this answer accurate. The classification depends on the design and intended use of the tank.

Pressurized tanks are designed to hold liquids at a pressure higher than atmospheric pressure, which may be necessary for certain substances that have a high vapor pressure or that need to be stored and transported under controlled conditions. These tanks can safely contain gases or liquids that would otherwise vaporize or expand at normal atmospheric pressure.

Nonpressurized tanks, on the other hand, are designed to store liquids at atmospheric pressure. They are commonly used for a variety of substances, including fuels and chemicals that do not require pressurization for safe storage.

The flexibility in the design and usage of above-ground storage tanks is what leads to the correct answer that they "can be either one," accommodating various storage needs across industries.