API Std 650 tanks in various sizes and capacities

Allowable compressive stresses shall be in accordance with 5.5.4 except that for aluminum alloy plate the allowable compressive stresses shall be reduced by the ratio of the modulus of compressive elasticity to 29,000 for values of (t – c)/R less than 0.0175 and by the ratio of the minimum yield strength for the aluminum alloy in question to 30,000 for values of (t – c)/R equal to or greater than 0.0175 (see 5.5.2 for definitions). In all other equations in this standard API Std 650 tanks where yield strength or modulus of elasticity is used, such as Equations 27 and 28, similar corrections shall be made for aluminum alloys.

The interior of API 650 storage tanks to be internally lined or coated must have all edges rounded to a minimum of 3 mm radius. Internal welds must be completely seal welded, ground smooth, and free from API Std 650 tanks surface porosity, pockets, and high spots. Remove weld spatter. Vendor as specified on API 650 storage tanks drawing must perform additional surface preparation.

Generally, external environment corrosion should be considered before design and construction of API Std 650 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.