Above-ground pressurized storage tanks are categorized by what factor?

• A. Volume capacity
• B. Pressure level
• C. Temperature rating
• D. Material compatibility

Answer: (B)

The key idea is that these tanks are classified by the pressure they’re designed to contain—the design or maximum working pressure. This matters because the energy stored at higher pressures is greater, so higher-pressure tanks require stronger construction, thicker walls, appropriate relief devices, and stricter inspection and safety controls. That pressure-based categorization guides how the tank is designed, operated, and regulated, including venting requirements and maintenance intervals.

Volume capacity tells you how much product it can hold, but doesn’t determine the safety category in the same way pressure does. Temperature rating matters for what temperatures the tank can safely operate in, and material compatibility determines what substances can be stored, but neither defines how the tank is categorized for hazard safety in the same way as its design pressure.