The soil corrosion tank foundation is mainly composed of sand layer and asphalt sand, and the tank bottom plate is located on the asphalt sand surface. Due to the alternation of full load and no-load in the tank, the influence of temperature and groundwater in winter and summer, cracks appear on the asphalt sand layer, causing the groundwater to rise close to the tank bottom plate and cause corrosion.
When the temperature of the oil tank is high, the groundwater around the tank floor evaporates, which increases the salt concentration and increases the corrosion degree. The oxygen concentration difference battery corrosion tank bottom plate and sand foundation are not in good contact, which is easy to produce oxygen concentration difference. For example, when compared with full load and no-load, poor contact r will occur under no-load condition. Moreover, due to the difference of air permeability between the tank periphery and the tank center, the oxygen concentration difference battery will also be caused. At this time, the central part will become anode and be corroded.
The anti-corrosion coating on the bottom surface of the bottom plate must be weldable, and the structure of the coating can not be damaged during welding, and the effective anti-corrosion time of the coating is required to be long.
If cathodic protection is not used, inorganic zinc rich coating is preferred. It has excellent heat resistance, aging resistance, strong adhesion, excellent hardness and wear resistance, solvent resistance and rust resistance. The paint film has cathodic protection effect. It belongs to water-based coating, which is non-toxic and odorless, simple in construction and easy to use.
Due to the barrier of the ring beam, the edge plate is the blind area of cathodic protection. After the tank is filled with oil, the edge plate is slightly upwarped, and rainwater is easy to flow into the gap between the edge plate and the foundation.
In order to prevent rainwater from entering the gap, asbestos rope is generally used to fill the gap, and then waterproof glue and glass fiber cloth are used for sealing. The disadvantages of this treatment method are very big, and can not play a good waterproof role.
A structure of "cutting the exposed corner of ring beam and welding a circle of round steel outside and below the edge plate" can also be adopted. The specific method is to cut the exposed corner of ring beam, weld a circle of D6 round steel at the outer and lower edge of the edge plate for the built storage tank, and seal and fill the welding position with waterproof sealant after welding. This structure can effectively control the water entering into the gap between the edge plate and the foundation, reduce the water accumulation caused by the edge plate warping, and the construction is convenient and the effect is good.
Shandong Linyi Bosi conductive materials Co., Ltd. is a high-tech enterprise specializing in the production of MMO flexible anode, conductive polymer flexible anode and titanium coated anode, mainly providing cathodic protection technology, engineering design, installation and technical services. Tel: 0539 3712117, 15588026668.