The main factors causing metal rust: relative humidity of the atmosphere at the same temperature, the percentage of water vapor content and water vapor saturation content in the atmosphere, known as relative humidity. Under certain relative humidity, the corrosion rate of metal antirust oil is very small, but higher than the relative humidity, the corrosion rate increases suddenly. This relative humidity is called the critical humidity. When the humidity in the atmosphere is higher than the critical humidity, the metal surface will appear water film or water droplets, if the atmosphere contains harmful impurities, dissolved in the water film, water droplets, electrolytes and aggravate corrosion.

The strength of the hook net should be satisfactory: when the vehicle is traveling at 80 km/h, the hook net will not fall into the river when it bumps against the railings at a 15 degree Angle. The shape and color of the hook mesh should be in harmony with the surrounding natural environment. The phenomenon planning of important Bridges should be done well.

A. When the thickness of the plating is 3-4 mm, the zinc adhesion should be less than 460g/m, that is, the average thickness of the zinc layer is not less than 65 microns.

There are many kinds of zinc plating solution, which can be divided into plating solution and no plating solution according to its properties. The galvanized liquid has good dispersion and covering property, the coating crystal is smooth and fine, the operation is simple, the application range is wide, and the long-term use is in the production. However, due to the toxic substances contained in the plating solution, the gas escaping from the plating process has great harm to the health of workers, and the waste water must be treated strictly before discharge.