Fixed roof tank is an atmospheric tanks require vents to prevent pressure changes, which would otherwise result from temperature changes and withdrawal or addition of liquid. It is a type of storage tanks. These are designed as atmospheric, low, or high-pressure tanks and may be used to store hydrocarbons. Fixed roof tanks may be of cone roof or dome roof type construction. Dome roofs are usually supported from the shell by framing consisting of rafters and girders pressed to the roof radius.