A fixed roof tank is a type of

storage tank Storage tanks are containers that hold liquids, compressed gases (gas tank; or in U.S.A "pressure vessel", which is not typically labeled or regulated as a storage tank) or mediums used for the short- or long-term storage of heat or cold. The t ...

, used to store liquids, consisting of a cone- or dome-shaped roof that is permanently affixed to a cylindrical shell. Newer storage tanks are typically fully welded and designed to be both liquid- and vapor-tight. Older tanks, however, are often riveted or bolted, and are not vapor tight. A

breather valve In physics, a breather is a nonlinear wave in which energy concentrates in a localized and oscillatory fashion. This contradicts with the expectations derived from the corresponding linear system for infinitesimal amplitudes, which tends towards ...

(pressure-vacuum valve), commonly installed on many fixed roof tanks, allows the tank to operate at a slight internal pressure or vacuum. This valve prevents the release of vapors during very small changes in temperature, barometric pressure, or liquid level. Fixed roof tanks without breather valves will generally be freely vented; thus the emissions from a fixed roof tank can be non-trivial. Gauge hatches, sample wells, float gauges, and roof manholes provide accessibility to these tanks, and also act as potential sources of volatile emissions.

Applications

Storage tanks Storage tanks are containers that hold liquids, compressed gases (gas tank; or in U.S.A "pressure vessel", which is not typically labeled or regulated as a storage tank) or mediums used for the short- or long-term storage of heat or cold. The t ...

in general, and fixed roof tanks in particular, containing organic liquids can be found in many industries, including: * petroleum production and refining * petrochemical and chemical manufacturing * bulk storage and transfer operations * other industries consuming organic liquids Fixed roof tanks are typically used with products that have relatively low volatilities and

flash point The flash point of a material is the "lowest liquid temperature at which, under certain standardized conditions, a liquid gives off vapours in a quantity such as to be capable of forming an ignitable vapour/air mixture". (EN 60079-10-1) The fl ...

s. Using a fixed roof tank to store a product with high volatility can lead to product losses as vapors escape the enclosure.

References

{{reflist Storage tanks

Applications

See also

References