Tank blanketing

When you store gases and liquids in big tanks, sometimes the air above them can cause problems. The air can make the inside of the tank more or less pressurized, which can be bad for the things inside. One way to fix this problem is to put a blanket of gas (like nitrogen) on top of the liquid in the tank. The gas sits on top of the liquid and pushes down evenly, which helps keep everything inside the tank safe and happy. It's like putting a pillow on top of a stack of books so they don't get squished by something heavy that might fall on top.