Liquid storage tanks

Vertical cylindrical tanks, with flat bases and conical roofs, are universally used for the bulk storage of liquids at atmospheric pressure. Tank sizes vary from a few hundred gallons (tens of cubic metres) to several thousand gallons (several hundred cubic metres). 

The main load to be considered in the design of these tanks is the hydrostatic pressure of the liquid, but the tanks must also be designed to withstand wind loading and, for some locations, the weight of snow on the tank roof. 

The minimum wall thickness required to resist the hydrostatic pressure can be calculated from the equations for the membrane stresses in thin cylinders (Section 13.3.4)  

J = joint factor (if applicable), g = gravitational acceleration, 9.81 m/s2, ft = design stress for tank material, N/mm2, 

The liquid density should be taken as that of water (1000 kg/m3), unless the process liquid has a greater density. 

For small tanks a constant wall thickness would normally be used, calculated at the maximum liquid depth. 

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The maximum strain in a vertical liquid storage tank is given by e = pgHR/lEh where H is the level above the base of the liquid of density p, and h is the wall thickness of the tank. 

Figure 17 5. Combustible liquid storage tank in a nonenclosed, adequately ventilated area. (Reprinfed with permission from API RP 500.)...

FIGURE 5.1 Flammable Liquid Storage Tank P ID (from Ozog, 1985). 

FIGURE 5.2. Fault Tree Analysis of Flammable Liquid Storage Tank. 204... 

Aerobic. Leachate is removed from the bottom layer, piped to liquids storage tanks, and recirculated into the landfill in a controlled manner. Air is injected into the waste mass, using vertical or horizontal wells, to promote aerobic activity and accelerate waste stabilization. 

Where relief valves are provided on liquid storage tanks or vessels, where there is a possibility of liquid release, i.e., liquid slug, careful evaluation of the release disposal system (e.g., flare header) needs to be undertaken. In some cases, a liquid slug may block a header from releasing pressure and defeat the purpose of the pressure release system. 

Where enclosed spaces may produce overpressures blow out panels or walls are provided to relieve the pressure forces. The connections of the panel are specified at a lower strength that normal panels so it will fail at the lower level and relieve the pressures. Similarly, combustible or flammable liquid storage tanks are provided with weak roof to shell seams so that in case of an internal explosion, the built-up pressure is relieved by blowing off the roof and the entire tank does not collapse. 

Firefighting foam is the extinguishing agent typically utilized for flammable and combustible liquid storage tank protection. Protection is through fixed and manual systems for tanks. Such systems require ... 

After acute exposures to chlorine gas, both obstructive and restrictive abnormalities on pulmonary function tests have been observed. Eighteen healthy subjects exposed after a leak from a liquid storage tank had diminished FEVi, EEF 25-75%, and other flow rates within 18 hours of exposure. Follow-up studies at 1 and 2 weeks demonstrated resolution of these abnormalities in the 12 subjects with an initial chief complaint of cough, whereas the 6 subjects with a chief complaint of dyspnea had persistently reduced flow rates. Repeat studies in 5 months were normal in all patients studied except for mildly reduced flow rates in two patients who were smokers. ... 

Liquid storage tanks am provided with a certain amount of vapor space or freeboard, commonly 15% below 500gal and 10% above 500gal. Common erection practices for liquid storage tanks are ... 

We confine ourselves here to cylindrical tanks as an example. For free-standing liquid storage tanks the following formula applies to the design stress crD ... 

Fig. 27.1. Air separation plant with a front-end cleanup, cold box tower and liquid storage tanks. (Courtesy Air Liquide.)...

The heart of the system is the mixing chamber, where the liquid components must be thoroughly mixed without imparting turbulence. High-volume, high-pressure recirculating pumps from liquid-storage tanks accomplish continuous delivery of the components to the mold. Automatic controls are used to maintain precise flow and temperature of the plastic. 

Actual and Postulated Abnormal Releases. A few relatively minor incidents, resulting in releases of radionuclides, have occurred in the 10 years of operation of the WCF. As already stated, there have been no releases from the liquid storage tanks or the calcine bins. 

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