API Std 650 insulated tanks rim seals

X-ray inspection is mainly applicable to the internal inspection of pressure bearing parts and materials of metal oil tanks such as API Std 650 insulated tanks. It can clearly find the blocky defects inside the welded joints. However, the cost and resource consumption of radiographic testing are large. Magnetic particle testing can effectively detect the surface and near surface defects of API Std 650 insulated tanks etc. metal oil tanks, but magnetic particle testing can not effectively identify the internal defects of oil tanks.

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 Std 650 insulated tanks 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.

The internal floating plate of internal floating roof tank of API 650 tank is different from that of open floating plate of API Std 650 insulated tanks External floating roof tank of API 650 tank, so it is impossible to have rain and snow load.