API 650 self-anchored flat-bottom tanks qualification of welders

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 self-anchored flat-bottom 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 API 650 specification provides guidelines for the API 650 self-anchored flat-bottom tanks design, manufacturing, materials, installation and inspection of welded vertical and cylindrical tanks. Such containers must be on the ground and have a closed or open top.

API 650 self-anchored flat-bottom tanks Oil measuring hole: The oil measuring hole is used to measure the height, temperature and sampling of the oil stored in the tank, and is installed near the tank top platform. API 650 self-anchored flat-bottom tanks Fire extinguisher: The fire extinguisher (also known as the flame arrestor) of the oil tank is composed of a fire box, a copper wire mesh and an aluminum partition. It is installed under the breathing valve or safety valve to prevent sparks and air from entering the inside of the tank through the breathing valve or safety valve and causing accidents.