Which description matches an internal floating roof tank?

• A. An external floating roof with fixed roof on top
• B. A fixed roof with no floating components
• C. A completely open-top tank
• D. A multi-layer insulated roof system

Answer: (A)

Internal floating roof tanks rely on a roof that actually floats on the liquid surface inside the tank, reducing the vapor space and minimizing losses, while the tank also has a fixed roof above it. The description that references a floating roof alongside a fixed roof captures this setup: you still have a fixed top, but there is a floating component inside that moves with the liquid level. This is what differentiates an internal floating roof tank from a fixed-roof tank (no float) or an external/open-top design (no internal float). The other options do not describe a roof that floats on the liquid inside, which is the defining feature of an internal floating roof tank.