Steel structure sluice gate is an important component for controlling water level in hydraulic structures such as hydropower station, reservoir, sluice and ship lock. It should be submerged underwater for a long time, with frequent alternation of dry and wet during opening and closing, and be washed by high-speed water flow. In particular, the water line part is affected by water, sunlight and aquatic organisms, as well as water wave, sediment, ice and other floating objects, and the steel is easy to corrode, It significantly reduces the bearing capacity of steel gate and seriously affects the safety of hydraulic engineering. Some are protected by coating, which generally fails after 3 ~ 5 years of use, with low work efficiency and high maintenance cost.

Corrosion not only affects the safe operation of the structure, but also consumes a lot of human, material and financial resources to carry out anti-corrosion work. According to the statistics of some sluice gate projects, the annual expenditure for gate anti-corrosion accounts for about half of the annual maintenance cost. At the same time, a large number of labor force should be mobilized to remove rust, paint or spray. Therefore, in order to effectively control the corrosion of steel, prolong the service life of steel gate and ensure the integrity and safety of water conservancy and hydropower projects, the long-term anti-corrosion problem of steel gate has attracted extensive attention.

Corrosion environment of steel structure sluice gate and factors affecting corrosion:

1.Corrosion environment of steel structure sluice gate

Some steel sluice gates and steel structures in water conservancy and hydropower projects are immersed in various water quality (seawater, fresh water, industrial wastewater, etc.) for a long time; Some are often in a dry wet environment due to water level changes or gate opening and closing; some will also be impacted by high-speed water flow and friction of sediment, floating debris and ice; The part on the water surface or above the water is also affected by the humid atmosphere of water evaporation and splashing water mist; Structures working in the atmosphere are also affected by sunlight and air. Because the working environment of hydraulic gate is bad and there are many influencing factors, it is necessary to analyze the corrosion factors.

2. Corrosion factors

(1) climatic factors: the water parts of the steel structure sluice gate are easy to be corroded by the sun, rain and humid atmosphere.

(2) surface condition of steel structure: roughness, mechanical damage, cavitation, welding defects, gaps, etc. have a great impact on corrosion.

(3) stress and deformation: the greater the stress and deformation, the worse the corrosion.

(4) water quality: the salt content of fresh water is low, and the corrosion of gate varies depending on its chemical composition and pollution; Seawater has high salt content and good conductivity. Seawater contains a large amount of chloride ions, which is highly corrosive to steel. The corrosion of steel gate in seawater is more serious than that in fresh water.