Erection of API 650 welded tanks for oil storage

Inspection of weld and micro crack of API 650 welded tanks for oil storage: the inner and outer surface of API 650 welded tanks for oil storage, weld and heat affected zone shall be observed by naked eyes first. 100% ultrasonic testing or 100% penetrant testing are carried out for butt welds of API 650 welded tanks for oil storage. For the defects found by 100% magnetic particle inspection, dye detection, 100% ultrasonic inspection or 100% penetrant inspection, the radiographic inspection shall be used again to ensure the accuracy of the test results.

Large Low-Pressure Tanks Corrosion Allowance
In cases in which the rate of corrosion is closely predictable, additional metal thickness over and above that required for the initial operating conditions shall be provided and shall be at least equal to the expected corrosion loss during the desired life of the tank.
When corrosion effects are indeterminate before the tank is designed (although they are known to be inherent to some degree in the service for which the tank is to be used), and when corrosion is incidental, localized, or variable in rate and extent, the best judgement of the API 650 welded tanks for oil storage designer must be exercised in establishing reasonable maximum excess tank wall thicknesses. For all tanks that come under this classification, a minimum corrosion allowance of 1/16 in. shall be provided.

Lateral braces between outer bay rafters must be provided if asymmetrical structural shapes are used for rafters and if the API 650 welded tanks for oil storage API 650 tanks are located in areas subject to earthquakes. The bracing must be adequately sized for the seismic zone specified.