The inner wall of the tank is corroded

Internal corrosion is mainly divided into gas phase and liquid phase: the top of the tank is not in direct contact with the oil belongs to gas phase corrosion, according to the principle of atmospheric corrosion, its essence is still electrochemical corrosion; The inner wall of the middle of the tank is in direct contact with the oil, which belongs to liquid phase corrosion. The corrosion form is mainly chemical corrosion of the oil and electrochemical corrosion of the electrolyte contained in the oil, and this part is the lightest corrosion. The corrosion of the lower part of the tank wall and the inside of the tank bottom is the key part of the corrosion in the tank. The corrosive medium is the condensate water of the working process such as oil storage and transfer, and a certain water layer will be accumulated at the bottom when the discharge is not timely. For some strategic storage tanks, the water layer is permanently contained at the bottom due to the inconvenient removal of the transportation demand. At the same time, it contains a large number of sulfate-reducing bacteria, soluble hydrogen sulfide, carbon dioxide, etc. Its electrical conductivity is close to 3%NaCI, so it is highly corrosive.

The outer wall of the tank is corroded

There are three types of corrosion on the outer wall of storage tank, namely atmospheric corrosion, corrosion after water invasion of insulation layer and soil corrosion.

For the burst leakage in the atmosphere, subjected to atmospheric corrosion, atmospheric corrosion is also divided into: Marine atmosphere, industrial atmosphere, urban atmosphere and rural atmosphere. The corrosion rate of metal structures at different locations is also different, and the corrosion rate of metal structures in the Marine atmosphere is the highest.

The foundation of most storage tanks is mainly composed of sand layer and asphalt sand. The storage tank is located on the surface of the asphalt sand. Due to the constant change of the liquid in the tank, the asphalt sand will crack, causing the groundwater to rise close to the bottom of the tank and cause corrosion.

Therefore, the use of advanced anti-corrosion technology. Controlling the harm of corrosion and reducing the loss caused by corrosion are the key issues that should be considered in engineering design.