Fixed roof tank explained

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.[1] Fixed roof tanks without breather valves will generally be freely vented;[2] 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.[3] [4]

Applications

Storage tanks in general, and fixed roof tanks in particular, containing organic liquids can be found in many industries, including:

Fixed roof tanks are typically used with products that have relatively low volatilities and flash points.[5] Using a fixed roof tank to store a product with high volatility can lead to product losses as vapors escape the enclosure.[6]

See also

Notes and References

  1. Web site: BNH Gas Tanks. Fixed Roof Tank. 5 December 2015.
  2. Web site: South Coast Air Quality Management District. Supplemental Instructions For Liquid Organic Storage Tanks. 5 December 2015.
  3. Web site: Werner Sölken. Explore the World of Piping - Introduction to Storage Tanks. 5 December 2015.
  4. Web site: USA Environmental Protection Agency. Alternative Control Techniques Document:Volatile Organic Liquid Storage in Floating and Fixed Roof Tanks. 5 December 2015.
  5. Web site: Buckeye Fire Equipment. Storage Tanks: Fixed or Semi-fixed Systems. 5 December 2015.
  6. Web site: ISEC Company. Fixed Roof Tank.