ASTM A36 plates API standard 650 vertical welded storage tanks

The design metal temperature of API standard 650 vertical welded storage tanks each component exposed to the liquid or vapor being stored shall be the lower of the following:
a)The minimum temperature to which the tank contents will be refrigerated, including the effect of subcooling at reduced pressure.
b)The minimum metal temperature anticipated when the atmospheric temperature is below the refrigerated temperature (see 4.2.1). The effectiveness of the insulation in keeping the metal temperature above the expected minimum atmospheric temperature shall be considered.

Normal pressure API 650 storage tank: When the gas side pressure of API 650 storage tank is the same as atmospheric pressure or less than 13 atmospheres (gauge), API standard 650 vertical welded storage tanks is called atmospheric storage tank. API 650 petroleum storage tanks low pressure storage tank: when the pressure is greater than 13 atmospheres (gauge) and less than 0.1MPa, it is called low pressure storage tank.

Generally, external environment corrosion should be considered before design and construction of API standard 650 vertical welded storage tanks and so on storage tanks. The corrosion on the outer surface of storage tank is often worse than that on the inner surface. Especially in the chemical industry area, there are often acid fog, alkali or salt dust in the atmosphere. These impurities form an active corrosive medium with dew or steam and oxygen in the atmosphere. The corrosion of the external environment of the storage tank shortens the maintenance period of the storage tank, even causes the storage tank to be scrapped in advance, which affects the normal operation of the storage and transportation.