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The corrosion of the inner wall of crude oil tank and sewage tank bottom is mainly caused by electrochemical corrosion and bacterial corrosion caused by crude oil deposition sewage, and the crude oil deposition sewage at the tank bottom has high salt content and high temperature, so it has strong corrosion.
At present, the sacrificial anode method is widely used for cathodic protection of tank bottom wall. This method is safe and reliable for storage tank, and does not need special management, and has good protection effect. Magnesium and magnesium alloys, zinc alloys and aluminum alloys are commonly used as sacrificial anode cathodic protection materials. The anode block is evenly arranged on the bottom plate of the storage tank, and the steel plate is directly welded with the anode block.
According to the protection area, protection period and dielectric resistivity, the number of anodes required is calculated, so as to select the anode size and shape. The anode is evenly distributed on the bottom plate of the tank, and the anode support is welded with the bottom plate. The sacrificial anode is easy to install, and when the anode consumption is 85% of the initial weight, the tank cleaning opportunity can be used to replace the anode.
The main reasons for the corrosion of tank bottom plate are as follows: due to aging and cracking of asphalt sand layer at the tank bottom, the water in the foundation can penetrate into the tank bottom through the cracks, so that the outer wall and bottom plate of the tank will be corroded; rainwater may penetrate along the side wall of the tank through the gap between the tank bottom plate and the asphalt sand, forming an oxygen concentration difference battery between the areas with different air permeability, and is often a large cathode In the mode of small anode, local corrosion rate is particularly fast, and there may be autocatalytic effect of crevice corrosion in crevice; corrosion of stray current; existence of sulfate reducing bacteria; unqualified construction quality, such as unqualified welding seam or chloride ion brought in with sea sand as foundation. All of the above factors may cause corrosion of the outer wall and bottom plate of the storage tank. At present, impressed current protection method is widely used for cathodic protection of tank bottom plate outer wall, and sacrificial anode protection engineering can be used for small storage tank.
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: +86 17568010262£¬0539-3712117.