Browse suppliers of storage tank roofs on the Tank Storage Directory, including Fixed-roof, External floating roof (FR), Internal floating roof (IFR) and Domed external floating roof tanks.
An external floating roof tank is a storage tank commonly used to store large quantities of petroleum products such as crude oil or condensate. It consists of an open- topped cylindrical steel shell equipped with a roof that floats on the surface of the stored liquid. The roof rises and falls with the liquid level in the tank. As opposed to a fixed roof tank there is no vapor space (ullage) in the floating roof tank (except for very low liquid level situations). In principle, this eliminates breathing losses and greatly reduces the evaporative loss of the stored liquid. There is a rim seal system between the tank shell and roof to reduce rim evaporation. The roof has support legs hanging down into the liquid. At low liquid levels the roof eventually lands and a vapor space forms between the liquid surface and the roof, similar to a fixed roof tank. The support legs are usually retractable to increase the working volume of the tank. A fixed roof tank is a type of storage tank, 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 (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. Storage tanks 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. Reproduced under https://creativecommons.org/licenses/by-sa/3.0/