Pressure vessels

A gas holder or gasholder, also known as a gasometer, is a large container in which natural gas or town gas (coal gas or formerly also water gas) is stored near atmospheric pressure at ambient temperatures. The volume of the container follows the quantity of stored gas, with pressure coming from the weight of a movable cap. Typical volumes for large gas holders are about 50,000 cubic metres (1,800,000 ft3), with 60-metre-diameter (200 ft) structures. Gas holders now tend to be used for balancing purposes to ensure that gas pipes can be operated within a safe range of pressures, rather than for actually storing gas for later use.